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See detailSustainable energy conversion through the use of Organic Rankine Cycles for waste heat recovery and solar applications
Quoilin, Sylvain ULg

Doctoral thesis (2011)

This thesis contributes to the knowledge and the characterization of small-scale Organic Rankine Cycles (ORC). It is based on experimental data, thermodynamic models and case studies. The experimental ... [more ▼]

This thesis contributes to the knowledge and the characterization of small-scale Organic Rankine Cycles (ORC). It is based on experimental data, thermodynamic models and case studies. The experimental studies include: 1. A prototype of small-scale waste heat recovery ORC using an open-drive oil-free scroll expander, declined in two successive versions with major improvements. 2. A prototype of hermetic scroll expander tested on vapor test rig designed for that purpose. The achieved performance are promising, with expander overall isentropic effectivenesses higher than 70% and cycle efficiencies comparable or higher than the typical efficiencies reported in the scientific literature for the considered temperature range. New steady-state semi-empirical models of each component are developed and validated with the experimental data. The global model of the ORC prototype allows predicting its performance with a good accuracy and can be exploited to simulate possible improvements or alternative cycle configurations. Dynamic models of the cycle are also developed for the purpose of evaluating the system's reaction to transient conditions. These models are used to define and compare different control strategies. The issues of cycle optimization and fluid selection are treated using the steady-state semi-empirical models. The thermodynamic optimization of such cycles is first demonstrated by practical examples. Furthermore, three different methods for fluid selection are proposed, investigated and compared. Their respective advantages and fields of application are described. Finally, two prospective studies of small-scale ORC systems are proposed. The first one is a solar ORC designed for the rural electrification of remote regions in Africa. This prototype aims at competing with the photovoltaic technology, with the advantage of generating hot water as by-product. The second prospective study deals with the recovery of highly transient heat sources. Advanced regulation strategies are proposed to address the practical issues inherent to such systems. These strategies are compared with the state-of-the-art strategies and show a non-negligible potential of performance improvement. [less ▲]

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See detailCompétitivité des filières rizicoles burundaises: le riz de l'Imbo et le riz des marais
Gahiro, Léonidas ULg

Doctoral thesis (2011)

Le riz est une culture récente, pratiquée surtout dans la plaine de l'Imbo et dans les marais de moyenne altitude du Burundi. D'une part, les ressources disponibles et les technologies de production ... [more ▼]

Le riz est une culture récente, pratiquée surtout dans la plaine de l'Imbo et dans les marais de moyenne altitude du Burundi. D'une part, les ressources disponibles et les technologies de production rendent le riz de l'Imbo plus compétitif que le riz des marais. D'autre part, la majorité des qualités locales s'avèrent moins compétitives que celles importées de l'Asie et la Tanzanie. [less ▲]

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See detailContribution au développement d'un dispositif expérimental d'atomes froids de fer et spectroscopie à ultra-haute résolution de cet atome
Krins, Stéphanie ULg

Doctoral thesis (2011)

Le présent travail est dédié à la conception, la modélisation et l'implémentation d'un dispositif expérimental visant, pour la toute première fois, à piéger et à refroidir par laser des atomes de fer ... [more ▼]

Le présent travail est dédié à la conception, la modélisation et l'implémentation d'un dispositif expérimental visant, pour la toute première fois, à piéger et à refroidir par laser des atomes de fer. Dans ce cadre, une contribution majeure au développement de ce dispositif est rapportée ici. Cette contribution comprend notamment la mise en place de dispositifs de stabilisation laser sub-MHz adaptés aux transitions spécifiques de l'atome de fer à 372 et 358 nm, ainsi que l'implémentation d'un ralentisseur Zeeman sur des faisceaux de ces atomes issus d'un four à haute température. Par ailleurs, des déterminations à ultra-haute résolution de grandeurs spectroscopiques fondamentales liées aux effets isotopiques et de structure hyperfine des transitions à 372 nm et 373.7 nm du fer sont rapportées pour la toute première fois. Une comparaison extrêmement précise de la position de la raie du fer à 358 nm par rapport à la raie de l'iode moléculaire R(90)3-10 à 13957.8542 cm-1 est également présentée. Cette comparaison met à disposition avec la précision requise la dernière donnée spectroscopique qui était inconnue dans la littérature scientifique pour une mise au point optimale du refroidissement laser d'atomes de fer. Elle ouvre la voie à l'implémentation finale du dispositif présenté dans ce travail. [less ▲]

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See detailResidual Stress in Veneering Ceramic
MAINJOT, Amélie ULg

Doctoral thesis (2011)

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See detailOn the dichotomic collective behaviors of large populations of pulse-coupled firing oscillators
Mauroy, Alexandre ULg

Doctoral thesis (2011)

The study of populations of pulse-coupled firing oscillators is a general and simple paradigm to investigate a wealth of natural phenomena, including the collective behaviors of neurons, the ... [more ▼]

The study of populations of pulse-coupled firing oscillators is a general and simple paradigm to investigate a wealth of natural phenomena, including the collective behaviors of neurons, the synchronization of cardiac pacemaker cells, or the dynamics of earthquakes. In this framework, the oscillators of the network interact through an instantaneous impulsive coupling: whenever an oscillator fires, it sends out a pulse which instantaneously increments the state of the other oscillators by a constant value. There is an extensive literature on the subject, which investigates various model extensions, but only in the case of leaky integrate-and-fire oscillators. In contrast, the present dissertation addresses the study of other integrate-and-fire dynamics: general monotone integrate-and-fire dynamics and quadratic integrate-and-fire dynamics. The main contribution of the thesis highlights that the populations of oscillators exhibit a dichotomic collective behavior: either the oscillators achieve perfect synchrony (slow firing frequency) or the oscillators converge toward a phase-locked clustering configuration (fast firing frequency). The dichotomic behavior is established both for finite and infinite populations of oscillators, drawing a strong parallel between discrete-time systems in finite-dimensional spaces and continuous-time systems in infinite-dimensional spaces. The first part of the dissertation is dedicated to the study of monotone integrate-and-fire dynamics. We show that the dichotomic behavior of the oscillators results from the monotonicity property of the dynamics: the monotonicity property induces a global contraction property of the network, that forces the dichotomic behavior. Interestingly, the analysis emphasizes that the contraction property is captured through a 1-norm, instead of a (more common) quadratic norm. In the second part of the dissertation, we investigate the collective behavior of quadratic integrate-and-fire oscillators. Although the dynamics is not monotone, an “average” monotonicity property ensures that the collective behavior is still dichotomic. However, a global analysis of the dichotomic behavior is elusive and leads to a standing conjecture. A local stability analysis circumvents this issue and proves the dichotomic behavior in particular situations (small networks, weak coupling, etc.). Surprisingly, the local stability analysis shows that specific integrate-and-fire oscillators exhibit a non-dichotomic behavior, thereby suggesting that the dichotomic behavior is not a general feature of every network of pulse-coupled oscillators. The present thesis investigates the remarkable dichotomic behavior that emerges from networks of pulse-coupled integrate-and-fire oscillators, putting emphasis on the stability properties of these particular networks and developing theoretical results for the analysis of the corresponding dynamical systems. [less ▲]

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See detailStudy of the ecology, population structure and dynamic of the macroalgae Codium elisabethae in Faial (Azores) with underwater visible imagery.
Sirjacobs, Damien ULg

Doctoral thesis (2011)

Codium elisabethae O.C. Schmidt is a dark green globose macroalgae isolating an internal sea water volume in a lumen. Codium elisabethae is endemic to the Macaronesian region and is very similar to Codium ... [more ▼]

Codium elisabethae O.C. Schmidt is a dark green globose macroalgae isolating an internal sea water volume in a lumen. Codium elisabethae is endemic to the Macaronesian region and is very similar to Codium bursa C. Agardh whose distribution range spans the West-European, North-Western African and Mediterranean coasts and which was proposed as a potential indicator of coastal environmental changes based on the study of its ecology, revealing its long lifespan. Until recently, relatively little was known on Codium elisabethae as compared to the more widespread Codium bursa. To fill this gap, the present research aimed at producing an accurate description of the ecology and population dynamics of Codium elisabethae occupying the rocky shores of the Monte da Guia Special Area of Conservation (SAC)/Natura 2000 network (Faial, Azores). To achieve this, two reference sites were selected for long term monitoring: a sheltered no-go reserve exhibiting a dense Codium elisabethae population (Caldeirinhas), and a location experiencing more exposed conditions holding a sparser population (Ponta Furada). First, environmental conditions experimented by benthic organisms were extensively quantified and interpretated in regard to topographical particularities of each site. The study of reproduction dynamics showed a persistent summer fertility and an important vegetative reproduction. Important nutrient concentration ratio was found between the Codium elisabethae lumen water and surrounding sea water (mean ratios: nitrates: 5.7; ammonium: 3.4; phosphates: 3.1). In situ counting’s and size measurements revealed much higher densities of young recruits in the site of the Caldeirinhas (order of 20 ind/m²) than in the one of Ponta Furada (order of 1/m), for both summer and winter. Secondly, underwater visible imagery was exploited as an efficient and non-invasive alternative to classical in situ population estimation. Between August 2003 and November 2005, fifteen seabed photo coverages were collected by scuba-divers. Subsequent image processing consisted in mosaicing, interactive identification, and automatic change detection methods. This allowed quantifying the seasonal fluctuations of population structures (density, percentage cover and biomass) and of population dynamics (growth, recruitment, mortality and primary production). Chi-square tests of image-derived estimates and in situ measurements confirmed the validity of a centimeter precision for the estimation of population structure of individuals above 4 cm diameter. Important variability of population structure and density was observed within the sites at small spatial scales. Significant differences of population structure and dynamics parameters are demonstrated between two close-by but contrasting coastal habitats. Population density showed a sharp reduction in autumn 2003 and did not recover fully in spring and summer 2004. During the following year, population of the protected site maintained density and biomass, while at the exposed site population density dropped. In contrast with conclusions from earlier studies on the Azorian Codium elisabethae and on the Mediterranean Codium bursa, the present study revealed higher biomass (34 - 730 g dry wt.m-²), growth rates (up to 2.5 cm/month in summer) and primary production (0.53 – 11.5 g dry wt.m-².day-1), and demonstrated the seasonal fluctuations of these parameters for the studied Azorian Codium elisabethae population. The lifespan of Codium elisabethae was estimated to reach at least 7 years in the SAC of Monte da Guia based on an integration of average seasonal growth rates measured by imagery on extended population samples. This study demonstrates the high potential of registered underwater photomosaics time-series for long term surveys of macroalgae populations. This work provides also a strong framework to further developments and applicability to other species, which should be helpful to strengthen our current understanding of benthic ecosystem processes. [less ▲]

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See detailIo's interaction with Jupiter's magnetosphere
Dols, Vincent ULg

Doctoral thesis (2011)

Io, the innermost Galilean moon of Jupiter, is the most volcanic body of the solar system. This volcanism is responsible for a tenuous atmosphere composed mainly of S, O and SO2. This atmosphere is ... [more ▼]

Io, the innermost Galilean moon of Jupiter, is the most volcanic body of the solar system. This volcanism is responsible for a tenuous atmosphere composed mainly of S, O and SO2. This atmosphere is constantly bombarded by the plasma that co-rotates with the magnetic field of Jupiter, producing new ions and perturbing locally the magnetic field. This local perturbation is responsible for auroral emissions in the atmosphere of Jupiter, at the foot of Io’s flux tube. The spacecraft Galileo made five flybys of Io between 1995 and 2001 at very low altitude (~100’s km) and made plasma and magnetic field measurements that reveal the complexity of Io’s interaction with Jupiter. Past studies have tackled the modeling of this interaction using different complementary approaches, each shedding a new light on the issue but each involving some simplifications. The MHD models (Linker et al., 1998) are based on an a priori parameterization of the ionization in the atmosphere, generally assuming spherical symmetry and a single atmospheric and plasma species (representative of O and S). They ignore the important effect of the cooling of electrons as well as the multi-species composition of both the plasma and the atmosphere. The two-fluid approach (Saur et al., 1999) computes precisely the ionization and collisions in the atmosphere of Io but make the assumption of a constant magnetic field, limiting the self-consistency of the model and potentially introducing large quantitative errors. We combine a multi-species chemistry model of the interaction that includes atomic and molecular species with a self-consistent Hall-MHD calculation of the flow and magnetic perturbation to model as self-consistently as possible the plasma variables along the different flybys of Io by the Galileo probe. [less ▲]

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See detailMODELISATION DE L’ACTIVITE DES BACTERIES DU SOUFRE EN LAGUNAGE
Harerimana, Casimir ULg

Doctoral thesis (2011)

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See detailSignal transduction in photodynamic therapy-mediated cell death
Coupienne, Isabelle ULg

Doctoral thesis (2011)

Les glioblastomes sont des tumeurs du cerveau comptant parmi les plus fréquentes et les plus agressives. En effet, l’espérance de vie médiane des patients est d’environ quinze mois après diagnostic ... [more ▼]

Les glioblastomes sont des tumeurs du cerveau comptant parmi les plus fréquentes et les plus agressives. En effet, l’espérance de vie médiane des patients est d’environ quinze mois après diagnostic. Malgré d’intenses recherches et l’utilisation de traitements combinant la chirurgie, la radiothérapie et la chimiothérapie, le pronostic des patients n’a guère évolué depuis une vingtaine d’années. Ces tumeurs sont caractérisées par la présence de diverses altérations génétiques et, généralement, par une activation constitutive du facteur de transcription NF-κB. Étant un régulateur majeur de l’apoptose et de la survie cellulaire, ce facteur pourrait jour un rôle central dans la résistance des glioblastomes aux diverses thérapies. Au cours de ce travail, nous avons étudié les effets de l’inhibition du NF-κB sur la mort cellulaire des glioblastomes induite en réponse à un traitement par PDT, dont l’efficacité repose sur la production d’espèces réactives de l’oxygène suite à la présence simultanée d’un photosensibilisateur, de lumière et d’oxygène. Ainsi, nos résultats montrent que les cellules dans lesquelles le NF-κB est inhibé présentent une sensibilité accrue au traitement par rapport aux cellules non-inhibées. De plus, cette augmentation de mort cellulaire est majoritairement due à de la nécrose. Le traitement par PDT conduit également à l’apparition d’autophagie cytoprotectrice dont l’inhibition améliore l’efficacité du traitement. Nous nous sommes ensuite focalisés sur la mort par nécrose et avons démontré l’implication de la kinase RIP3 dans la mort nécrotique induite par PDT. Il est apparu que l’oxygène singulet produit au cours du traitement était à l’origine de la nécrose RIP3-dépendante. Cependant, les intermédiaires transductionnels et la manière dont le NF-κB exerce ses effets anti-nécrotiques demeurent encore inconnus. Enfin, afin de mieux comprendre le rôle joué par RIP3 dans la mort induite par PDT, nous avons utilisé la lignée d’ostéosarcome U2OS, déficiente en cette protéine, et au sein de laquelle nous en avons restauré l’expression. De manière surprenante, les cellules sauvages se sont révélées plus sensibles au traitement que les U2OS exprimant RIP3. De plus, la lignée RIP3-U2OS montre un taux d’apoptose supérieur à celui de son homologue sauvage. Cette divergence peut en partie s’expliquer par une induction d’autophagie plus importante au sein des RIP3-U2OS. Celle-ci, pouvant être un mécanisme pro-survie, peut leur conférer une protection contre la mort cellulaire en facilitant l’élimination des organelles endommagés. Enfin, nous avons déterminé que les cellules sauvages présentent un taux de nécrose plus important que les cellules RIP3-U2OS en réponse au traitement. Nos résultats ont dont permis de prouver (i) que l’inhibition du NF-κB améliorait la sensibilité des glioblastomes à la mort cellulaire induite par un traitement par 5-ALA-PDT, (ii) que celle-ci était, dans ce cas, majoritairement de la nécrose RIP3-dépendante et (iii) de mettre au jour un rôle pour RIP3 dans la régulation de l’apoptose et de l’autophagie induites par PDT. [less ▲]

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See detailLa résilience des banques libanaises : analyse de certains aspects de la gestion des risques dans le cadre de l'accord de Bâle
El Khoury, Ghada ULg

Doctoral thesis (2011)

Located in an environment of high uncertainty, supervisors in Lebanon have decided to comply with regulations issued by the Basel Accords and to monitor the new Basel Committee prudential framework. This ... [more ▼]

Located in an environment of high uncertainty, supervisors in Lebanon have decided to comply with regulations issued by the Basel Accords and to monitor the new Basel Committee prudential framework. This thesis focuses on the Lebanese banking sector and on Basel II specific aspects in the Lebanese context. Four research areas are covered : 1. Evaluation of the capitalization level of Lebanese banks as required by Basel II prudential standards. 2. Lebanese sovereign risk analysis and its impact on the sustainability of banks through the measurement of probability of default of the Lebanese state on its Eurobonds denominated in U.S. dollars. 3. Examining the question of bank balance sheet procyclicality generated by the accounting and prudential framework, and by contextual factors specific to the resilience of the Lebanese banking sector. 4. Evaluation of the adaptation level of the Lebanese banking sector to new risk management approaches by estimating the probability that banks will well manage their risks. From a comparative analysis of the regulatory and economic capital, we found that 14 banks have a high economic capital relative to regulatory capital under Basel II in 2005. We also observed that the risks faced by Lebanese banks are primarily related to credit risk and sovereign risk in particular. Applying the valuation model of default risk, developed by Merrick (2001), and based on a review of scientific literature, we proposed a synthetic measure of credit risk of the Lebanese US dollar denominated Eurobonds. The results show that changes in the probability of default and recovery rates are explained by the trust vis-à-vis the market and state. Based on a review of the scientific literature, we have developed theories of economic fluctuations and financial instability. The analyses of procyclicality in the Lebanese context have shown that the factors leading to a balance sheet procyclicality in the Lebanese banking sector are atypical. We have also shown the resilience of the Lebanese banking sector to recent shocks and crises. Through a survey conducted between November 2009 and February 2010, we assessed the level of adaptation of the Lebanese banking sector to new risk management approaches. The results show that some banks have become more aware of the importance of developing proper risk management practices. Therefore, other banks remain in a precarious stage. [less ▲]

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See detailExtension of the Liège Intranuclear Cascade Model to the 2-15 GeV Incident Energy Range
Pedoux, Sophie ULg

Doctoral thesis (2011)

The Liège Intra-Nuclear Cascade model (INCL4) has been shown to be quite successful for the description of spallation reactions. However its validity domain is limited to an upper incident energy of ~2 ... [more ▼]

The Liège Intra-Nuclear Cascade model (INCL4) has been shown to be quite successful for the description of spallation reactions. However its validity domain is limited to an upper incident energy of ~2 GeV, because inelastic elementary processes are restricted to the excitation and de-excitation of the Delta resonance. In this thesis, the INCL4 model is extended to higher incident energy. This is realised by including other inelastic elementary collisions, direct multipion production in elementary nucleon-nucleon and pion-nucleon collisions. This is somehow opposite to the usual extension to high energy of such models, as it is usually realised by including excitation of heavier baryonic resonances. Experimental data and isospin symmetry have been exploited in the implementation of multipion channels, but we could not avoid to introduce specific models for the energy-momentum and charge repartition on the final pions. The predictions of the modified model for production of protons, neutrons and charged pions by proton and pion beams off nuclei are compared with experimental data. A short study on nuclear fragmentation is also presented. [less ▲]

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See detailBouncing droplets, the role of deformations
Terwagne, Denis ULg

Doctoral thesis (2011)

Nowadays, innovative applications such as "lab-on-a-chip", micro-reactors or biological chips are developed for industry, biology or medicine. Capillary issues are encountered which are not yet fully ... [more ▼]

Nowadays, innovative applications such as "lab-on-a-chip", micro-reactors or biological chips are developed for industry, biology or medicine. Capillary issues are encountered which are not yet fully understood. It is therefore essential to open up ways to manipulate tiny amounts of liquid in order to mix them, encapsulate them or to create emulsions. The bouncing droplets on an oscillating liquid interface allow their manipulation. Indeed, under certain conditions, droplets can bounce indefinitely on a bath surface as long as the squeezed air film which separates the drop from the bath is renewed at each bounce. We chose to study deformable droplets on a non-deformable bath. The droplets are deformable because they are large or made of a low viscous oil, the liquid of the bath being highly viscous silicone oil. We investigated how the deforma- tions, the stability and the trajectories of the droplets depends on the forcing parameters such as the frequency and the amplitude of the oscillation. We also studied the possibility of mixing and emulsifying droplets on the bath. Finally, we showed the effect of the deformation of the bath on these bouncing droplets and studied the trajectories of walking droplets [1] which are used as a model for quantum-like particles [2-5]. In this manuscript, we reported an exploration of the droplets behavior as a function of the ability of the bath and/or the droplet to deform. Depending on the forcing frequency, specific deformation modes are excited on the bouncing droplets. We used these modes to rationalize their bouncing stability and to create double emulsions in a compound droplet. Then, we determined numerically the complex bifurcation diagrams of the trajectories of a bouncing droplet thanks to a model based on a spring. On a low viscous bath, we evidenced the importance of its deformation. We showed that a walker exists as soon as the droplet experiences, once every two oscillation periods, a jump high enough to trigger a Faraday wave. As a consequence, we have to take the bouncing droplets into account when looking for an alternative way to manipulate them or as a model of quantum-like particles. The bouncing droplets still exhibit lots of intriguing behaviors which have yet to be explained. They can therefore remain the focus of future works. [less ▲]

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See detailApplication de la spectroscopie Raman à l’analyse de colorants sur fibres de coton dans le contexte de la criminalistique
Lepot, Laurent ULg

Doctoral thesis (2011)

Forensic examination of textile fibres is based on fibre morphology and on fibre material and dyes characterization. Cotton is the most frequently used fibre in textiles but also the most encountered in ... [more ▼]

Forensic examination of textile fibres is based on fibre morphology and on fibre material and dyes characterization. Cotton is the most frequently used fibre in textiles but also the most encountered in casework. While man-made fibres show various morphologies and materials, cotton is a natural cellulosic fibre with constant morphology. Cotton fibres examination can consequently be summarized in the characterization of fibre dyes. However forensic needs require non-destructive, fast and sensitive techniques. For fibres microspectrophotometry (MSP) is the commonly used technique and the obtained UV-Vis absorption spectrum reflects dyes used to colour the fibre. Any other technique suitable for dye characterization is thus helpful to reinforce MSP results on cotton fibres. Raman spectroscopy is a fast non-destructive technique, easy to integrate into the fibre analytical sequence without any additional sample preparation. Moreover it provides specific molecular information and seems convenient for the study of coloured molecules. This work allowed to demonstrate the potential of the technique in dyed cotton fibres examination through the characterization of pure dyes but also the ability to detect different components in dye mixtures. In order to help dye identification spectral databases were built using Raman spectra collected in the present work. Unfortunately such a database will never be exhaustive and the identification of an unknown dye would be compromised. An interesting option is to identify the general chemical class of the unknown dye, especially to evaluate its rarity. The recognition of some dye chemical classes has been made by the mean of characteristic peaks but this method remains somewhat subjective. This subjectivity can be bypassed using chemometric techniques; they are able to predict chemical class membership on the basis of Raman specific information. Some experiments have been performed on Raman spectra using PCA models and the SIMCA classification tool. [less ▲]

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See detailStudy of the Cape Ghir upwelling filament using variational data analysis and regional numerical model
Troupin, Charles ULg

Doctoral thesis (2011)

Aim: Upwelling filaments are shallow, elongated structures of cool waters often visible in the regions of coastal upwelling. The present thesis aims to improve our knowledge on the mechanisms responsible ... [more ▼]

Aim: Upwelling filaments are shallow, elongated structures of cool waters often visible in the regions of coastal upwelling. The present thesis aims to improve our knowledge on the mechanisms responsible for the generation of filaments. Location: the study is centered on the Canary Current Upwelling system, located off northwest Africa, in particular around Cape Ghir (30°38'N, 9°53'W), where these filaments are frequently observed. Methods: - We compiled historical in situ data to build a high-resolution climatology of temperature and salinity in the region of interest using the Data Interpolating Variational Analysis (\diva) method. - We ran the experiments with the numerical model ROMS to investigate the processes responsible for the filament generation. - We collected in situ measurements during a cruise in August-September 2009, in the frame of the CAIBEX project, in the filament area and analyzed them to get a detailed description of the Cape Ghir filament, its variability and its biogeochemical characteristics. - We computed anomalies of several variables with respect to a long-term mean to examine the time-evolution of the Canary Current Upwelling system. Results: The climatology showed improvements with respect to existing products, especially in the coastal area, and was a valuable asset to provide initial and boundary conditions for the numerical model. The results of the simulations underlined the role of the wind in the filament generation and confirmed our assumption of a mechanism based on the potential vorticity balance. Preliminary analysis of the cruise data allowed us to characterize the filament physical and biological properties, in particular we observed the signal of a subsurface (at a depth of 300~m) anticyclonic eddy on the northern flank of the filament, also present in the numerical model outputs. Anomalies for the year 2010 revealed a widespread warming over the tropical and subtropical Atlantic Ocean and a diminution of the upwelling activity. We attributed these anomalies to a weakening of the winds, itself related to a strongly negative North Atlantic Oscillation (NAO) index. [less ▲]

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See detailImpacts des changements climatiques passés et présents sur la génétique et la démographie du Cincle plongeur (Cinclus cinclus)
Hourlay, Frederic ULg

Doctoral thesis (2011)

Climate change is emerging as the greatest threat to natural communities in many, if not most, of the world’s ecosystems in coming decades. Numerous studies have revealed present and probable future ... [more ▼]

Climate change is emerging as the greatest threat to natural communities in many, if not most, of the world’s ecosystems in coming decades. Numerous studies have revealed present and probable future consequences that climate change will have on many animal and vegetal species. According to these studies, birds could be affected, mostly negatively, in various ways : distribution, abundance, phenology, ethology ... The purpose of this work is to determine how the White-throated Dipper (Cinclus cinclus), a Palearctic, temperate, passerine bird that is exclusively associated with flowing water, reacted to the climate changes that occurred during the Pleistocene, and how climate change currently affects this species : - For this purpose, we conducted a phylogeographic study : we analysed three fragments of mtDNA (i.e. fragments coding for cytochrome b, ND2 and domains II and III of the controle region) from 106 tissue samples originating from 24 dipper populations, mostly located in the Western Palearctic. - The second part of this work consisted in analysing ringing recoveries and nest-boxes frequentation from a dippers population settled on the river Syre and its tributaries (Luxemburg) and followed from 1979 to 2001. Populations census were also conducted on different water courses in Luxemburg, in order to determine dipper habitat preferences. 1. Phylogeography of the dipper in the Western Palearctic region In spite of a low genetic variability, the results of our phylogeographic study reveal a complex phylogeographic structure for this species with at least five distinct lineages for the Western Palearctic region. As for many species of the Western Palearctic fauna and flora, this genetic structure is probably linked to the isolation of populations in different southern refuges during glacial periods. Furthermore, the isolation of populations in Scandinavia and/or Eastern regions, but also in Morocco and probably in Corsica, was accentuated by ecological and biogeographic barriers during Quaternary interglacial periods. During glacial periods, Italy, Sicily and the Balkano-Carpathian region acted as major refuge zones for the dipper. At the end of the last ice age, Western Europe was repopulated by dippers from a refuge located in Italy and, probably, South-East France, while Eastern Europe was recolonised by Balkano-Carpathian birds. A large contact zone between these two lineages was evidenced and extends from Luxembourg to Hungary. Finally, our results indicate the need to clarify the taxonomic status of the dipper, especially concerning the European subspecies whose validity appears uncertain. 2. Dipper demography – Influence of climate change and other anthropic pertubations Results obtained from the analysis of demographic and morphologic variables of the Luxemburger population are in agreement with results obtained from other European populations. Differences observed between these populations are mostly due to climate and habitat quality differences. However, other factors could also partly explain these differences. As for other places in Europe, nest boxes installation dramatically increased dippers population size on the river Syre. Our results also suggest that the installation of nest boxes could influence some demographic and morphologic variables, probably as a result of population increase. But, above all, our results show how temperatures and precipitations affect these variables, and particularly laying dates. Climatic changes that occurred during the last decades provoked earlier laying dates. Whereas clutch size and nest size remained unchanged, the Luxemburger population size decreased during the same period, as observed for other European populations. The main cause to this decrease should be an increase of environmental instability inducing notably a decrease of food ressources for dippers. As a result, we observed a significant decrease of females body weight during this period. Climate change will also probably have a serious impact on dipper genetic diversity, leading to the disappearance of the most southern populations and eventually of certain genetic clades. The results obtained concerning the taxonomic status of the dipper and its demography could be useful in the framework of a conservation program, if necessary. In this perspective, the development of habitat suitability prediction tools, as the one we developed, could also be very helpful. [less ▲]

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See detailUnveiling the internal structure and evolution of massive stars through their pulsation modes
Godart, Mélanie ULg

Doctoral thesis (2011)

Stars in the night sky are not as quiet as they seem. A human being wandering on Earth few billions years ago would have seen a different night sky, with different stars forming different constellations ... [more ▼]

Stars in the night sky are not as quiet as they seem. A human being wandering on Earth few billions years ago would have seen a different night sky, with different stars forming different constellations. Moving forward in time, he would have been the witness of stellar evolution as some stars would have suddenly shined while others disappeared forever. Hard to realize at a time scale of human life, stars are born, evolve, and die in a limited lifetime which can last only a few million years for the most massive to trillion years for the less massive. Fortunately, it is not necessary to wait that long to study the formation and evolution of stars. Stellar evolution can be studied on shorter time scales, on thousands of stars, at various evolutionary stages. This is of great importance as stars shape the Universe and produce the chemical elements at the origin of life. Probing the internal structure of stars is however very challenging due to the opacity barrier of their superficial layers. One way to get around this issue is to study and interpret stellar pulsations. As seismologists extract information about Earth interior trough the study of earthquakes, asteroseismologists can study the internal structure of stars by studying their oscillations. In this thesis, this technique is used to study the internal structure and evolution of massive stars which are at least eight times more massive than our Sun and which have a spectral type between O and B. The first part of this work is devoted to the determination of the $\kappa$-mechanism instability domains for massive stars. In order to extend the computations to the post-main sequence phase of evolution, we develop a numerical technique in which the non-adiabatic computations for the stellar core are made, independently than for the envelope, within the quasi-adiabatic and the asymptotic treatment. In a second step, we investigate the pulsations modes in O main sequence stars and in B post-main sequence stars. The presence of g-modes in post-main sequence stars is closely related to the internal structure of the star and we study the effects of several physical factors on the occurrence of these modes. Finally, the last part of this work is dedicated to the characterization of strange mode pulsations. In particular, we focus on strange modes having an adiabatic counterpart, which are trapped into a superficial cavity. The effect of the model atmosphere on the excitation is investigated in addition to the characterization of their eigenfunctions. [less ▲]

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See detailNarrateur, personnage et leceur virtuel: vers une méthode d'analyse intra-relationnelle
Goin, Emilie ULg

Master's dissertation (2011)

Dans l'étude d'un possible dialogisme entre les instances internes au récit que sont le narrateur, le personnage et le lecteur virtuel (soit l'instance de lecture présupposée par le texte), ce travail ... [more ▼]

Dans l'étude d'un possible dialogisme entre les instances internes au récit que sont le narrateur, le personnage et le lecteur virtuel (soit l'instance de lecture présupposée par le texte), ce travail pose notamment les questions des subjectivèmes, de leur assemblage en point de vue et des articulations de points de vue hétérogènes: comment peut-on les repérer, identifier différentes formes d'assemblage/articulation et déterminer leur force illocutoire? [less ▲]

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See detailDes indications sur un détour. Les rapports entre Althusser et Spinoza
Mancuso, Eva ULg

Master's dissertation (2011)

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See detailCaractérisation des effets de température dans la zone endommagée autour de tunnels de stockage de déchets nucléaires dans des roches argileuses
Dizier, Arnaud ULg

Doctoral thesis (2011)

La solution du stockage des déchets nucléaires de haute activité et de longue durée de vie dans les couches argileuses profondes comporte de nombreuses incertitudes. Pour combler celles-ci de nombreux ... [more ▼]

La solution du stockage des déchets nucléaires de haute activité et de longue durée de vie dans les couches argileuses profondes comporte de nombreuses incertitudes. Pour combler celles-ci de nombreux projets européens sont réalisés de façon à les minimiser. Le projet TIMODAZ (Thermal Impact On the Damaged Zone Around a Radioactive Waste Disposal in Clay Host Rocks) étudie l'influence de la température sur la zone endommagée. Cette zone correspond à une zone soumise à la redistribution des contraintes lors de l'excavation constituant un lieu de développement de micro et macro fractures. Cet endommagement mécanique est complété par un endommagement thermique lors de la pose des canisters qui vont émettre de la chaleur durant des milliers d'années et donc provoquer une augmentation de la température du massif argileux. Cette élévation de température de l'argile peut faire apparaitre des déformations plastiques thermiques de contraction. Cette nouvelle plasticité peut contribuer au développement de la zone endommagée. L'objectif de ce travail est donc de caractériser la zone endommagée autour des tunnels souterrains, construits dans l'Argile de Boom, soumis à des élévations de température induites par les déchets nucléaires. Durant ce travail, une loi de comportement thermo-mécanique est implémentée. Celle-ci se base sur un "modèle à chapeau" étendu à la thermo-plasticité. Ce modèle comprend la combinaison d'un modèle à frottement interne, d'un critère Cam-Clay et d'un critère de rupture à la traction. Ce modèle est étendu à la température et en particulier à la thermo-plasticité en considérant les travaux de Sultan. Les paramètres thermo-hydro-mécaniques de l'Argile de Boom sont identifiés et servent à la modélisation d'expériences de laboratoire et in situ. Ces expériences consistent en outres en un cylindre creux, en l'expérience de chauffage ATLASIII et en l'expérience à grande échelle PRACLAY. Ces trois expériences ont pour objectif d'étudier l'Argile de Boom d'une petite échelle à une plus grande représentative du massif argileux. L'étude du comportement dans la zone élastique et plastique est également prise en compte via ces différentes expériences. Les résultats, avec différentes lois de comportement, montrent que l'influence de la thermo-plasticité est faible mais non négligeable vis-à-vis des déformations déviatoriques engendrées par l'excavation. [less ▲]

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See detailInSAR Applied to the Study of Active Volcanic and Seismic Areas in Africa
Wauthier, Christelle ULg

Doctoral thesis (2011)

Two active volcanic areas situated in immature portions of the East African Rift System (EARS): the Lake Kivu (Dem. Rep. of Congo) and Lake Natron (Tanzania) regions, which are located in the western and ... [more ▼]

Two active volcanic areas situated in immature portions of the East African Rift System (EARS): the Lake Kivu (Dem. Rep. of Congo) and Lake Natron (Tanzania) regions, which are located in the western and eastern branch, respectively, are still poorly known. Both areas indeed lack of ground-based networks, due to security problems or difficult field accessibility. The Lake Kivu area includes two volcanoes erupting frequently: the Nyamulagira and Nyiragongo volcanoes. The SAR database covering these volcanoes in- cludes data from JERS, ERS-1&2, ENVISAT, ALOS, RADARSAT-1&2 satellites back from year 1996. SAR Interferometry (InSAR) is thus applied to study the ground de- formations. MT-InSAR approaches, such as the ”‘StaMPS”’ method, are used to give us new complementary information to better constrain the previous established eruption models, or gain new insights on eruptions missed by the conventional InSAR, as well as on magmatic and tectonic activity. When enough constrains are available, the ground displacements are modeled using a 3D-Mixed Boundary Elements Method combined with a neighborhood algorithm. Hence, the 1996, 2002, 2004 and 2010 eruptions of Nyamu- lagira are modeled. The modeling results, coupled with the StaMPS MT-InSAR results, bring new insights concerning the magma plumbing system of this poorly known volcano and its eruptive mechanisms. The collapse of the eastern flank of Nyamulagira, along the NNW-trend fractures network linking Nyamulagira and Nyiragongo volcanoes, can also be identified. InSAR also captures the ground displacements associated with the January 2002 Nyiragongo eruption. The modeling of this major event evidences a deep magma intrusion beneath the Lake Kivu. Such intrusions should be taken into account for hazard assessment. The magma could indeed finds its way to the Lake Kivu floor, as evidenced by the presence of several old phreato-magmatic cones, and causes a lake overturn. The low dikes overpressures found in the North Kivu and Lake Natron areas indicate that, although the rift is considered as immature, the rift extension is driven by the supply of magma from depth, rather than by the tectonics. A new criterion to identify the rifting stage is found to be the stress state. In the southern part of the rift, tectonic activity dominates, indicating that the tectonics is probably driving the rift opening there. [less ▲]

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See detailDynamique des transactions foncières et vulnérabilité rurale au Niger : cas des communes rurales de Tchadoua et Yaouri
Lawali Mani, Sitou ULg

Doctoral thesis (2011)

Summary In Niger, agriculture is the principal activity of the rural populations. Unfortunately the access to the land becomes very difficult to the farmers in the center-south of the country. This area ... [more ▼]

Summary In Niger, agriculture is the principal activity of the rural populations. Unfortunately the access to the land becomes very difficult to the farmers in the center-south of the country. This area is confronted to the space saturation and the emergence of the land transactions whose causes, process and impacts on the agricultural households are little known. The study undertaken in the rural municipality of Tchadoua and Yaouri aimed at analyzing the dynamics of the land transactions in bond with the rural vulnerability in terms of the stakes of access and management of the grounds, but also their securisation. The problems were studied with a multidisciplinary approach. The analyses (quantitative and qualitative) were carried out on the basis of the data collected in the village areas of Maijanguero and Gomba through cards of investigations and semi-structured interviews with a sample of 30% of the households. We also used participatory observations of agricultural practices and consultation of different sources of documentation. Administration and others authorities have been also interviewed aswel as members of the land commissions and the intermediaries of the transactions. The results obtained show that the problem of access and management of the land in these agricultural areas is an important concern for rural producers. The land blocking due to the strong demographic pressure and the increase of economic stakes (crop rent) influence the excessive parceling out of the grounds and the individualization of the farms. This individualization supports consequently, the emergence of the commercial land speculations for the profit of the economic operators installed from now in logic of monopolization of grounds. The purchase, the pledge and the lease constitute the principal access modes to the ground instead of old forms of solidarity (gift, loan). Also, the new agrarian initiatives of assistance appear and take part in the improvement of the socio-economic conditions of the rural households. The results also made it possible to highlight a diversity of trajectories of the exploitations. The land ‘’monetarisation’’ influenced strongly the land management and reinforced the exclusion of the vulnerable groups. The strong changes of technical transformation and farming system are observed. It as revealed as the land accumulation or ‘’décapitalisation’’ depends of the type of farm, its strategy and its revenue. Indeed, three tendencies become apparent from the trajectories: great manufacturing units with dominant commercial accumulate land, use the hired labor work and araw cash crop (souchet); a strong land ‘’decapitalisation’’ at the extremely vulnerable and without viable strategy of adaptation in the long term. Lastly, the small farm witch made a diversification and a strong intensification, and there resist to the multiple attempts of land spoliation. These last constitute a model of stable and durable farm whose strategy is based primarily on the agricultural intensification through effective and less expensive agroforestry practices to increase their production and their land capital. The informel and discrete character of land transactions and the networks of intermediation by which are negotiated the land sales accentuate the land insecurity and contribute to increase the land prices. The analysis of the securisation practices of the land rights proves that legal formalization though timid, reduced considerably the frequency of the rural conflicts and offers agricultural opportunities of investments. However, the land commissions encounter difficulties which, slow down the generalization of the legal formalization of transactions. All things considered, the land problem remains a central stake of development thus, the securisation of the land rights of the rural poor must be a priority of the priorities to reach a durable food safety. It is thus urgent to make the land commissions more operational in their giving the means of operation in order to ensure a broad diffusion of the procedures of formalization for more impact and also encouraging the producers through small subsidies to practice the carrying agri-environmental measurements. [less ▲]

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See detailLe Caire : carrefour des ambassades. Étude historique et diplomatique de la correspondance échangée entre les sultans mamlouks circassiens et les souverains timourides et turcomans (Qara Qoyunlu-Qaramanides) au XVes. d’après le BnF ms.ar. 4440.
Dekkiche, Malika ULg

Doctoral thesis (2011)

Pendant près de 250 ans, les sultans Mamlouks d’Égypte (1250) et de Syrie (1260) furent les représentants suprêmes de l’Islam aussi bien aux yeux des Musulmans que des Chrétiens d’Occident. Leur capitale ... [more ▼]

Pendant près de 250 ans, les sultans Mamlouks d’Égypte (1250) et de Syrie (1260) furent les représentants suprêmes de l’Islam aussi bien aux yeux des Musulmans que des Chrétiens d’Occident. Leur capitale, Le Caire, s’érigea en véritable carrefour des ambassades venues des quatre coins du monde connu alors. Cependant, presque rien des archives de cette dynastie ne nous est parvenu sous sa forme originale. Heureusement, les secrétaires de chancellerie de cette époque nous ont laissé un nombre non négligeable d’ouvrages, manuels de chancellerie et Formulaires, dans lesquelles ils nous révèlent les pratiques de chancellerie en cours alors et nous présentent de nombreuses copies de lettres qui furent échangées entre les sultans mamlouks et d’autres dynasties, musulmanes, chrétiennes ou autres. La présente thèse de doctorat se fonde sur l’un de ces formulaires, conservé sous sa forme manuscrite à la Bibliothèque Nationale de France, Paris, sous la cote ms. ar. 4440. Nous avons extrait de ce manuscrit un corpus de 19 lettres échangées entre les sultans mamlouks et trois autres dynasties musulmanes du XVes. régnant sur un territoire allant de l’Anatolie à l’Iran en passant par l’Iraq: les Timourides, les Qara Qoyunlu et les Qaramanides. Après l’édition critique de ce corpus, nous nous sommes concentrée sur l’étude historique et diplomatique de celui-ci. La première partie de la thèse concerne l’étude historique du corpus et de ce que nous avons appelé « la réalité de l’ambassade ». Le protocole de réception des ambassades au Caire par les sultans mamlouks, est assez bien renseigné à travers les chroniques des historiens de l’époque. Il est important de bien connaître ces règles afin de mesurer l’importance que le souverain accordait à son correspondant. Après énonciation de ces règles protocolaires, nous proposons, pour chaque dynastie en question, un aperçu de l’état des relations qui étaient établies entre elles et les sultans mamlouks, avant de nous atteler à l’étude historique du corpus proprement dite. Pour ce faire, nous avons dépouillé années après années les chroniques mamloukes et tenté de remettre chacune des lettres du corpus dans le contexte de l’ambassade qui lui était propre. Enfin, nous nous sommes concentrée sur le contenu des messages de ces lettres et avons analysé les raisons qui étaient à l’origine de l’envoi de l’ambassade. Nous nous sommes rendue compte de l’importance que ces lettres possèdent en tant que sources historiques de la période couverte, car elles nous révèlent un grand nombre de détails omis par les historiens contemporains des faits, ce qui nous permet de réévaluer avec plus de précision le rôle que la dynastie mamlouke jouait encore à cette époque notamment en tant que représentant suprême de la communauté musulmane et ce malgré les affronts subis par les différents pouvoirs montants, comme les Timourides. Nous avons grâce à l’analyse du protocole de cérémonie et du contenu des messages deux grilles de lecture nous permettant d’évaluer l’état des relations établies entre les Mamlouks et les trois autres dynasties, mais pour que l’étude soit complète, il est une troisième grille qui doit être prise en compte. Elle nous est fournie par la diplomatique et elle fait l’objet de la seconde partie de notre thèse. Dans cette partie, nous nous sommes concentrée, outre sur notre corpus, sur l’étude des manuels de chancellerie de l’époque mamlouke et nous avons tenté, grâce à eux, de reconstituer les règles de chancellerie propres à la rédaction de la correspondance entre les sultans mamlouks et les souverains musulmans afin de mesurer de façon certaine les liens qui sous-tendaient les relations établies entre les différents correspondants. Une telle étude vient à point lorsque l’on sait le retard que la discipline diplomatique a pris dans le cadre des études arabo-musulmanes. Enfin, la mise en parallèle de cette partie avec la première nous permet de dresser un tableau assez complet de la perception que les Mamlouks avaient des autres dynasties avec lesquelles ils étaient en contact. [less ▲]

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See detailElaboration d’un modèle d’écobilan de l’exploitation agricole irriguée. Cas du périmètre du Tadla – Maroc
Krim, Lhassan ULg

Doctoral thesis (2011)

In Morocco, the agro environmental problem is mainly translated by a degradation of the waters quality and a soils salinization under irrigation. In the, studied zone of the present work, the lands ... [more ▼]

In Morocco, the agro environmental problem is mainly translated by a degradation of the waters quality and a soils salinization under irrigation. In the, studied zone of the present work, the lands irrigation started since several decades by using waters of sometimes very degraded mineral quality, on one hand, and the agricultural intensification essentially marked by the application of excessive nitrogenous fertilizers doses, on the other hand, engendered a strong nitric pollution of groundwater table and a spectacular salinization of soils and waters. In order to contribute to the environmental assessment of the irrigated agriculture in Morocco, an Ecobalance model baptized "EcoTadla" (TEB) was elaborated and validated in the Tadla perimeter through the adaptation of the "EcoFerme" model (MEF) developed by the Fluid Mechanics and Environment Unity of the Gembloux Agro-Bio Tech – University of Liege (Belgium). The general objective is to establish an Ecobalance model allowing to quantify and to analyse the materials fluxes exchanged between the farm and its environment and consequently to improve and\or to correct the agricultural practices aiming at a better agro environment preservation within an eco-advice initiative framework. The analysis of the inadequacies of MEF to make an operational model in the studied context allowed to bring the adaptations to be brought as regards the definition of the basic hypotheses to hold in the new model construction, the quantification of the parameters to be used as inputs of the model and the modifications to be introduced into the modelling of the fluxes equations. The TEB model subdivides the farm into three compartments the “Cultivated soil”, the “Cultures” and the “Animals”. The farm (studied system) exchanges materials fluxes with its environment subdivided, in his turn, into four compartments: The “Network waters”, the “Under ground” the "Atmosphere" and the "Third parties". The Ecobalance calculation period is of twelve months equivalent to an agricultural campaign and elements, taken into account at present, in the fluxes calculation are: the nitrogen (N), the phosphor (P), the potassium (K), the calcium (Ca), the magnesium (Mg), the chlorine (Cl), the sodium (Na) and the water (H20). Considering the specificities of the agro environmental problem in the studied context, the TEB global model was conceived as a general program which calculates the Ecobalance for the various taken elements and which offers the possibility to the user to focus the study on three sub models: The "Water" model (WEB), the "Nitrogen" model (NEB) and the "Salts" model (SEB). These three models allow to quantify and to analyse the materials fluxes respectively for "Water", "Nitrogen" and "Salts" on the farm or perimeter scale during the period calculation. The TEB model was tested, verified and validated on an optimised network of representative farms. In order to characterize better the studied domain and clarify more the main parameters and the inputs required by the model, this network was the object of a farming follow-up in the form of inquiries, local measures and analyses in the laboratory of samples of water and soil during three agricultural campaigns (2002-2003, 2003-2004 and 2004-2005). WEB sub model quantify a total of 15 fluxes between these compartments which are two types: "major fluxes" and "minor fluxes". The lysimétrique follow-up led in two contrasted farms allowed to conclude that this model is reliable with an error risk varying from 17 to 26 %. The irrigation water use efficiency remains globally weak with an average of 40 % exceeding 50 % only in 25 % of the farmers of the follow-up network while the irrigation valuation water rate in the production is 56 % on average. Therefore, it’s necessary to award more eco-advice efforts to improve the efficiency and rationalize the irrigation water use. The analysis of the model sensibility demonstrated that the varying fact of this rate of 5 % and 10 % leads a variation respectively of 17 % and 36 % on the final result represented mainly by the infiltration rate which is the vector of the nitrogenous pollution and the salts washing. Ultimately, the Web model is a tool that can be used by the manager to improve eco advice on recovery and rational use of water in agricultural irrigation. Similarly, the quantification of the indicators presented would help the manager make the right choice of crops for better utilization of irrigation water The NEB sub model allows quantifying 17 fluxes between the farm and its environment. The nitrogen potential lixiviation flux, main indicator of the pollution risk the groundwater, is on average 77,8 kg N ha-1 on the follow-up network scale with a maximum of 105 kg N ha-1 and a minimum of 35 kg N ha-1. The lysimetric follow-up curried out shows that 14 % and 13 % of the residual mineral nitrogen was respectively washed during the 2003-2004 campaign and the 2004 2005campaign. So it’s necessary to make more eco advice efforts in terms of nitrate fertilizers use. The analysis of sensibility of the model showed that the rate mineralization variation of 5 % and 10 % engendered a variation of the “nitrogen potential lixiviation” flux respectively of 10 and 19 %. The NEB sub model is very useful for the manager can learn about the potentially leachable inorganic nitrogen and the nitrogen fertilizer made unnecessarily by comparing the doses recommended. The SEB model quantifies 8 main fluxes mostly salts conveyed by irrigation waters of and washing salts. On 15 farms of the Ecobalance follow-up network, this “potentially washable salts” flux is about 4210 kg ha-1 on average with a variation coefficient of 52 %. The lysimetric follow-up realized showed that 18 % and 12 % of salts were respectively washed during the 2003-2004 campaign and the 2004-2005 campaign. Consequently, it’s required to think about rehabilitation measures within an interdisciplinary framework aiming at the durability preservation of the production systems. The analysis of sensibility of the model showed that the electric conductivity rate variation of 5 % and 10 % engendered a variation of the «washing salts" flux respectively of 8 % and 16 %. The analysis of SEB model results in relation with the NEB model in 10 farms studied showed that, given the quality of water and soil, the reasoning of the nitrogen should be reflected according to the timetable and efficiency of irrigation-dependent process of leaching of salts, but also according to the vegetative stage of the plant for better utilization of soil mineral nitrogen. Ultimately, a policy of eco efficient and appropriate advice to the problem of environmental study area inevitably involves consideration of three elements "water", "nitrogen" and "salts ". The TEB program could be one of the fundamental tools of policy All these results impose to think to technical support strategies to set up follow-up devices of the ground, to strengthen the capacities of taking targeted measures to validate and verify the developed models and cheer the work in interdisciplinary by developing the collaboration such as integrated projects aiming at the sustainability of the agricultural production systems. By more clarifying the parameters used as inputs, these models would become more successful and more reliable [less ▲]

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See detailRôle de RIPK3 dans la mort induite par la thérapie photodynamique
Fettweis, Grégory ULg

Master's dissertation (2011)

La protéine RIPK3 (Receptor-interacting protein 3) a été montrée comme étant un activateur clé de la nécrose, mais il a également été constaté qu’il pouvait induire l’apoptose. L’objectif de cette étude ... [more ▼]

La protéine RIPK3 (Receptor-interacting protein 3) a été montrée comme étant un activateur clé de la nécrose, mais il a également été constaté qu’il pouvait induire l’apoptose. L’objectif de cette étude est de comparer le profil de la mort induite par la thérapie photodynamique (PDT) médiée par l’acide 5-aminolévulinique (5-ALA) dans la lignée U2OS déficiente en RIPK3 et dans des U2OS où l’expression de RIPK3 était restaurée de manière stable. Pour ce faire, nous avons évalué la survie cellulaire ainsi que les paramètres d’apoptose, de nécrose et d’autophagie. De manière surprenante, la survie des U2OS RIPK3 positives traitées par 5-ALA-PDT a été augmentée comparé aux U2OS sauvages. De plus, la mort des cellules RIPK3 positives était diminuée lors d’un prétraitement au zVAD-fmk. Un clivage plus important de PARP et des caspase-3, -7, -8 et -9 a été constaté dans les cellules contenant RIPK3, pointant le rôle essentiel de l’apoptose dans la mort induite par 5-ALA-PDT. En parallèle, nous avons observé une augmentation du flux autophagique et de manière surprenante, un plus faible niveau de nécrose que dans les cellules U2OS Wild types. De plus, la nécrose induite en présence de RIPK3 était dépendante de RIPK1 au contraire de la nécrose induite dans les cellules U2OS RIP3 négatives. L’expression de RIPK3 a induit un changement de profil de la mort induite par 5-ALA-PDT, mais aussi une meilleure survie cellulaire face à ce traitement. Cet accroissement de la survie, dont l’observation constitue une première pourrait être dû au flux autophagique augmenté en présence de RIPK3. Enfin, le biais par lequel RIPK3 sensibilise les cellules à l’apoptose, et le mécanisme régissant la nécrose induite en absence de RIPK3 par la 5-ALA-PDT ne sont pas encore connus. [less ▲]

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See detailSelection, efficacy, ecological characterization and formulation of fungal control agents against water hyacinth [Eichhornia crassipes (Martius) Solms] in Mali
Dagno, Karim ULg

Doctoral thesis (2011)

Rice and irrigated orchards are considered as the most important food and economical sources in Mali, which watered from Niger River. However, stable productions of rice and orchards products have been ... [more ▼]

Rice and irrigated orchards are considered as the most important food and economical sources in Mali, which watered from Niger River. However, stable productions of rice and orchards products have been limited by many disease, insects, and weeds. Recently, water hyacinth infestation in river of Niger has increased drastically and as affected by the decrease of water flow due to clogging dams and irrigation work. Biological control of weeds is an alternative approach to chemical herbicide use, focusing on the use of native fungal to control or reduce the population of water hyacinth. From 2006 to 2007, 1000 samples consisting of infected parts of water hyacinth were collected from the River Niger (District of Bamako, Segou and Niono with GPS coordinates “12° 40’ N, 7° 59’ W” ; “13° 26’ N, 6° 15’ W” and “14° 15’ N, 5° 59’ W” respectively) in Mali. Fungal belonging to seven genera (116 isolates in all) were recovered from surface-sterilized water hyacinth parts with pronounced blight symptoms. On the basis of in vivo pathogenicity tests in which the diseased leaf area percentage was estimated visually and disease severity was estimated (by calculating a disease severity index), three isolates emerged as causing severe disease: Fusarium sp. isolate Mln799 (DS = 70%), Cadophora sp. isolate Mln715 (70%), and Alternaria sp. isolate Mlb684 (71%), identified respectively as Gibberella sacchari (Anamorph. Fusarium sacchari), Cadophora malorum, and Alternaria sp. This is the first report to highlight C. malorum as a candidate biocontrol agent for water hyacinth. Influence of ecological parameter, water activity (0.880 - 0.960aw modified par glycerol) and temperature (15-35°C) on viable conidia and mycelial growth rate of Alternaria sp. (isolate Mlb684), F. sacchari (isolate Mln799) and C. malorum (isolate Mln715) were evaluated. Germination and mycelial growth dropped as aw of the medium decreased. Results showed a significant effect of aw, temperature and their interaction on mycelial growth (P < 0.0001). Growth models for F. sacchari (isolate Mln799), C. malorum (isolate Mln715) and Alternaria sp. (isolate Mlb684) differed slightly, with R2 values of 93.40, 85.89 and 77.31% respectively. Mycelial growth models, no different between predicted and experimental values was observed. Results confirm the previous finding that aw has greater influence on growth of F. sacchari (isolate Mln799), C. malorum (isolate Mln715) and Alternaria sp. (isolate Mlb684) than temperature. Analyse of 5 target regions of isolate Mlb684 genome (18 and 28S ribosomal RNA genes, Elongation factor-1 alpha gene, calmodulin gene and actin gene) allowed identifying this isolate as new specie in Alternaria genus. The strain has been deposited under accession number MUCL 53159 in the Industrial Fungal & Yeast Collection (BCCMTM/MUCL, Belgium) and DNA sequences have been deposited in GenBank. We have named it “Alternaria jacinthicola Dagno & M.H. Jijakli”. It was the first sequenced of calmodulin gene reported in Alternaria genus. Water hyacinth, paddy and wheat substrates for mass production of these biocontrol agents were evaluated. Greater sporulation of C. malorum (isolate Mln715) was observed on water hyacinth substrate (4.08 x 107 spores ml-1) following by wheat (1.06 x 107 spores ml-1). Biocontrol efficacy of fungal isolates found to be enhanced with unrefined Carapa procera (L) oil and refined palm oil supplemented with soybean lecithin in greenhouse. Applying C. malorum (isolate Mln715) and A. jacinthicola (MUCL 53159 strain) in vegetable oil emulsion [Carapa procera (L) and palm oils] caused 87.02 to 93.13% of damage severity on water hyacinth 6 weeks after treatment. Field trials showed lower efficacy control than greenhouse tests. In host specificity tests, neither C. malorum isolate Mln715 nor Alternaria sp. isolate Mlb684 showed any pathogenicity towards any member of a panel of 17 crop plants of economic importance in Mali. [less ▲]

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See detailTest de bronchoprovocation à la métacholine chez le cheval : relation avec l’inflammation des voies respiratoires profondes
Frippiat, Thibault ULg

Master of advanced studies dissertation (2011)

The clinical examination and the ancillary tests used in clinical routine may be poorly characteristics in horses suffering from subclinical inflammatory airway disease or in clinical remission of ... [more ▼]

The clinical examination and the ancillary tests used in clinical routine may be poorly characteristics in horses suffering from subclinical inflammatory airway disease or in clinical remission of recurrent airway obstruction (RAO). Methacholine bronchoprovocation test, which is used for diagnosis of human asthma, has been used in some studies in horses, but none have examined his potential diagnostic interest. The objective of this study was to determine whether this test may represent an applicable and repeatable method for the diagnosis of an increased susceptibility to bronchospasm in horses, and whether there is a relationship between this test and the markers of inflammation in the bronchoalveolar lavage. Eight horses (6 with RAO history and 2 controls) were used. They underwent bronchoprovocation tests 2 times at 24h interval. They were then tested before and after 7 days of an environmental challenge. Simultaneously, bronchoalveolar lavages were done for the measurement of several inflammatory markers. The test has a good feasibility and significant repeatability. Dust exposure increased the bronchoreactivity, while it did not significantly affect other clinical and functional parameters or inflammatory makers. In the future, the bronchoprovocation test could therefore find its place in clinical practice for the detection of asymptomatic horses which are susceptible to develop bronchospasm in poorer environmental conditions. [less ▲]

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See detailGeometric optimization algorithms for linear regression on fixed-rank matrices
Meyer, Gilles ULg

Doctoral thesis (2011)

Nowadays, large and rapidly evolving data sets are commonly encountered in many modern applications. Efficiently mining and exploiting these data sets generally results in the extraction of valuable ... [more ▼]

Nowadays, large and rapidly evolving data sets are commonly encountered in many modern applications. Efficiently mining and exploiting these data sets generally results in the extraction of valuable information and therefore appears as an important challenge in various domains including network security, computer vision, internet search engines, bioinformatics, marketing systems, online advertisement, social networks, just to name a few. The rapid development of these modern computer science applications sustains an ever-increasing demand for efficient machine learning algorithms that can cope with large-scale problems, characterized by a large number of samples and a large number of variables. The research reported in the present thesis is devoted to the design of efficient machine learning algorithms for large-scale problems. Specifically, we adopt a geometric optimization viewpoint to address the problem of linear regression in nonlinear and high-dimensional matrix search spaces. Our purpose is to efficiently exploit the geometric structure of the search space in the design of scalable linear regression algorithms. Our search space of main interest will be the set of low-rank matrices. Learning a low-rank matrix is a typical approach to cope with high-dimensional problems. The low-rank constraint is expected to force the learning algorithm to capture a limited number of dominant factors that mostly influence the sought solution. We consider both the learning of a fixed-rank symmetric positive semidefinite matrix and of a fixed-rank non-symmetric matrix. A first contribution of the thesis is to show that many modern machine learning problems can be formulated as linear regression problems on the set of fixed-rank matrices. For example, the learning of a low-rank distance, low-rank matrix completion and the learning on data pairs are cast into the considered linear regression framework. For these problems, the low-rank constraint is either part of the original problem formulation or is a sound approximation that significantly reduces the original problem size and complexity, resulting in a dramatic decrease in the computational complexity of algorithms. Our main contribution is the development of novel efficient algorithms for learning a linear regression model parameterized by a fixed-rank matrix. The resulting algorithms preserve the underlying geometric structure of the problem, scale to high-dimensional problems, enjoy local convergence properties and confer a geometric basis to recent contributions on learning fixed-rank matrices. We thereby show that the considered geometric optimization framework offers a solid and versatile framework for the design of rank-constrained machine learning algorithms. The efficiency of the proposed algorithms is illustrated on several machine learning applications. Numerical experiments suggest that the proposed algorithms compete favorably with the state-of-the-art in terms of achieved performance and required computational time. [less ▲]

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See detailMultidisciplinary study of trophic diversity and functional role of amphipod crustaceans associated to Posidonia oceanica meadows
Michel, Loïc ULg

Doctoral thesis (2011)

Posidonia oceanica is the most abundant seagrass of the Mediterranean Sea. It can cover extensive areas with monospecific formations, called meadows. These meadows, whose extent is estimated to about 40 ... [more ▼]

Posidonia oceanica is the most abundant seagrass of the Mediterranean Sea. It can cover extensive areas with monospecific formations, called meadows. These meadows, whose extent is estimated to about 40,000 km2, are critical features of the Mediterranean coastal zones. Moreover, they shelter important biomass and biodiversity of vagile invertebrates. Among these invertebrates, amphipod crustaceans are, alongside gastropod mollusks and polychaete annelids, one of the dominant groups. Amphipods are key-features of other temperate seagrass systems. As they are generally primary consumers, they are important in the transfers of organic matter from producers to higher rank consumers. In addition, their grazing activity on the epiphytes that grow on the seagrasses influence the dynamics of the epiphytic cover, and therefore the functioning of the whole meadow as an ecosystem. However, the situation in Mediterranean Posidonia oceanica meadows is still unclear. In particular, several lacks of information limit the comprehension of actual trophic ecology of amphipods, and of the impact of their feeding activity on the meadow functioning. In this context, the main goal of this work was to enhance the knowledge of the trophic diversity and the functional role of amphipods associated to Posidonia oceanica meadows. To achieve this, we structured our research in three main tasks. For each of these tasks, we chose Calvi Bay (NW Corsica, France) as study site, and all sampling and experimentation was undertaken from the STARESO research station (University of Liège). The first task (chapter 3) was the study of the precise composition of the amphipod community structure at our study site, and its temporal variation at day/night and seasonal scale. Our results show that the fauna of Posidonia oceanica meadows of Calvi Bay is abundant and diverse. The density and the structure of the community were different in each season (November, March and June), probably in relation with meadow parameters such as foliar surface, epiphytic biomass and abundance of litter in the meadow. Moreover, day/night variations were very important. Most amphipods performed vertical migrations that could be a mechanism to avoid predation and/or competition for food and habitat. The comparison of three sampling techniques (hand-towed net, litter collection and light traps) yielded deeply different results, suggesting that each of them only collects a subset of a complex assemblage. Combination of several sampling methods is therefore advised to have a holistic and accurate view of the community. These faunistic data also allowed highlighting the most abundant and/or representative species of the studied community. These include Apherusa chiereghinii, Aora spinicornis, Dexamine spiniventris, Amphithoe helleri, Caprella acanthifera, Gammarella fucicola and Gammarus aequicauda. These species were therefore chosen as target species for the second task. The second task (chapter 4) was the assessment of the extent of interspecific trophic diversity among the studied community. This phenomenon could indeed be important to limit food competition. We tried to perform a full reconstruction of the diet of the dominant species of the community and to evaluate the contribution of each of the potential food items offered by the meadow (animal and vegetal epiphytes from the leaves, rhizomes and litter fragments, SPOM, BPOM, living and dead P. oceanica material). To have an accurate view of the dietary habits of the dominant species, we used a triple strategy based on the joint use of traditional methods (gut content examination) and trophic markers (stable isotopes of C & N, fatty acids). The combination of these three methods proved to be successful, as each method had specific strengths and weaknesses. Overall, results indicate that all dominant species relied on macroalgal epiphytes for a large part of their diet. Our insights were unfortunately limited by the poor discrimination between potential food items, due to high inter-source similarity. Considerable interspecific differences could nonetheless be highlighted, notably concerning preferences of epiphytes from leaves or litter fragments vs. epiphytes from rhizomes. In addition, most species had a mixed diet, and relied on several food items. None of the examined species seemed to graze on their seagrass host, but Gammarus aequicauda partly relied on seagrass leaf detritus. Contribution of microepiphytes (e.g. diatoms) to the diet of amphipods was apparently anecdotical. Our data also suggested the existence of a certain extent of intraspecific trophic diversity that should be taken into account for future work. In the third and final task (chapter 5), we aimed to put the data obtained in the first two parts of this study in the wider context of the functioning of the Posidonia oceanica meadow as an ecosystem. We used in vitro and in situ microcosms experiments to characterize the interaction between epiphytes and amphipods from a triple point of view (resource depletion, resource assimilation by the consumer and secondary production), and to understand how amphipod grazing could influence the dynamics of the epiphytic cover of the leaves of P. oceanica. Amphipod grazing had no effect on the total epiphytic biomass, or on the encrusting epiphytes’ biomass. However, all three taxa (A. chiereghinii, D. spiniventris and Gammarus spp.) consumed significant amounts (45 to 90 % of total biomass) of erected epiphytes, both vegetal and animal. This selective top-down control might influence the structure and biomass-specific productivity rates of the epiphytic cover. In addition, amphipod grazing caused an increase in N availability and residence time. Through epiphyte removal and N enrichment, amphipods could boost seagrass production. Overall, amphipods of Posidonia oceanica meadows could be seen as ecosystem engineers. Assimilation of the consumed epiphytes was clear for all taxa. However, the utilization of this biomass for secondary production was hard to measure, due to low survival rates of animals. In fine, by combining in situ sampling and microcosm experimentation, and trough the joint use of traditional and innovative techniques, we showed that feeding activity of amphipods influence their biotope through several effects, and that they could be pivotal items of Posidonia oceanica meadows. In doing so, we improved, to some extent, the understanding of these critically important, yet endangered ecosystems. [less ▲]

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See detailToxicocinétique du sélénium chez les tortues. Exposition in vivo chez Trachemys scripta scripta
Dyc, Christelle ULg

Master's dissertation (2011)

Le sélénium est un élément essentiel possédant un seuil « carence-excès » très étroit. L’étude toxicocinétique de cet élément, constitue une étape préliminaire importante à la compréhension des effets ... [more ▼]

Le sélénium est un élément essentiel possédant un seuil « carence-excès » très étroit. L’étude toxicocinétique de cet élément, constitue une étape préliminaire importante à la compréhension des effets néfastes qu’il est susceptible de causer chez les populations de reptiles. Une expérimentation impliquant 130 tortues de Floride juvéniles (Trachemys scripta scripta) a été réalisée. Le groupe contrôle a été alimenté avec une nourriture de base, alors que les deux conditions expérimentales ont reçu une nourriture supplémentée avec 64 µg/g et 134 µg/g de séléno-L-méthionine (PS), pendant huit semaines. L’accumulation du Se a été mesurée dans le foie, les reins, le muscle, la peau, les écailles, la carapace et le sang, ce qui a permis d’observer que le transfert trophique du sélénium se réalisait de manière dose-dépendante. Durant quatre semaines supplémentaires, une cinétique d’élimination du Se a également pu être observée. De plus, la concentration en Se dans le sang, dans la carapace et dans la peau est apparue fortement corrélée à celle des tissus internes. Cette observation semble intéressante pour la mise en place d’un biomonitoring peu invasif des tortues dans leur milieu naturel. Les concentrations toxiques auxquelles les tortues ont été soumises n’ont pas permis de détecter d’effets néfastes au niveau de la croissance, de la prise alimentaire et de la survie des tortues. [less ▲]

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See detailResidency Patterns, Abundance and Social Composition of Bottlenose Dolphins (Tursiops truncatus) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg

Master of advanced studies dissertation (2011)

Residency patterns, abundance and social composition of bottlenose dolphins (Tursiops truncatus) were assessed during 2008-2010 in Bahía San Antonio (BSA), Patagonia, Argentina. A total of 462.3 survey ... [more ▼]

Residency patterns, abundance and social composition of bottlenose dolphins (Tursiops truncatus) were assessed during 2008-2010 in Bahía San Antonio (BSA), Patagonia, Argentina. A total of 462.3 survey hours resulted in 80.7 contact hours with in total 107 dolphin groups. Data indicated that dolphins spend most of their time resting, feeding and travelling in BSA, although their time-budget changed over the different seasons. As such, dolphins increased their time feeding and socializing during winter and spring, whereas during summer they spent up to 46% of their time diving, a behaviour presumably associated with a tail out/peduncle-dive foraging strategy. Dolphin groups had a median size of 4 individuals ranging between 1 and 40. Group size seemed to vary significantly over the different seasons and behaviours, with groups being larger during winter and during socializing and feeding. Group size was further positively correlated with the presence of calves. A total of 63 dolphins were individually identified in the bay and re-identified up to 35 days. Of these, 57% could be regarded as resident in the area (year-long or seasonally), including all mother and calf pairs. Using the closed time heterogeneity model (Mth), and accounting for the proportion of unidentifiable individuals, calculations resulted in a maximum corrected abundance estimate of 97 and 83 individuals during winter, and a minimum abundance of 34 and 38 individuals during autumn of 2009 and 2010 respectively. At all times, between 25% and 68% of the population consisted out of unidentifiable individuals (juveniles and calves) depending on the season. Results further revealed that bottlenose dolphins in BSA associated at random and that the entire community existed out of two levels of casual acquaintances. Data presented herein suggest that the shallow and protected waters of BSA support a resident community of bottlenose dolphins, between 35 to 97 individuals depending on the season, living in a fission-fusion society in which companionships frequently change. It was further suggested that dolphins specifically use BSA to rest and feed, and that the region is preferred by females to give birth and raise their young, with a possible increased calving period during winter and spring based on an increasing prey availability. [less ▲]

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See detailDéveloppement d’approches complémentaires pour limiter la transmission virale par les pucerons dans la Province du Shandong
Bosquée, Emilie ULg

Master's dissertation (2011)

Nowadays, in China, the control of aphids lies on the systematic use of synthetic insecticides. A socio-economical analysis of rural households’ structure in the Shandong province was carried out. The ... [more ▼]

Nowadays, in China, the control of aphids lies on the systematic use of synthetic insecticides. A socio-economical analysis of rural households’ structure in the Shandong province was carried out. The latter highlighted the farmers’ unawareness of the chemicals’ harmful effects on the environment and on human health. This observation led to some research aiming at the development of new alternative methods that would be efficient for Chinese producers. Within this context of biological control against aphids and their virus transmission (Potato virus Y (PVY), Cucumber mosaic virus (CMV) et Potato Leaf Roll Virus (PLRV)), three semiochemical substances namely (E)-β-farnesene (EBF), cis-3-hexenyl acetate, garlic extract and peas intercropping were separately tested. Yellow traps were used and the treatments were applied on potatoes and courgettes fields. No significant difference is observed between the different treatments. However, a tendency for cultural association is showed. Another kind of biological control was envisaged: the use of lectins. In this study, the effects of three glycoproteins on the virus transmission of three non-persistant viruses were tested in laboratory on Myzus persicae via the use of artificial diets. The glycoproteins used were Canavalia ensiformis agglutinin (ConA), Galanthus nivalis agglutinin (GNA) and wheat germ agglutinin (WGA) as for the viruses; PVY, CMV and TuMV (Turnip Mosaic Virus). An interference between GNA and all viruses was observed. In addition, a competition between WGA and two viruses i.e. CMV and TuMV was highlighted. In consequence, the two latter lectins are considered as promising proteins. In order to share the results of this study with Chinese farmers, simplified technical specifications on the insect fauna of vegetable crops grown previously, the hazard of pesticides and on the tested alternative methods of control were written and distributed. [less ▲]

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See detailCaractérisation hydrogéologique du bassin du Lilot
Briers, Pierre ULg

Master's dissertation (2011)

Le Lilot, ruisseau de la région de Marchin (province de Liège) s’écoule majoritairement sur des formations givetiennes karstifiées. Ce contexte laisse supposer une forte vulnérabilité de l’aquifère ... [more ▼]

Le Lilot, ruisseau de la région de Marchin (province de Liège) s’écoule majoritairement sur des formations givetiennes karstifiées. Ce contexte laisse supposer une forte vulnérabilité de l’aquifère. Cependant, cette vulnérabilité n’est pas avérée car il faut encore qu’un volume suffisant de polluant s’infiltre et que le taux de renouvellement de l’aquifère ne puisse diluer cette contamination. De plus, rien n’indique que les eaux qui s’infiltrent au niveau des pertes rejoignent la nappe aquifère. L’objectif de ce travail est d’effectuer une caractérisation hydrogéologique du bassin et d’étudier les interactions entre les eaux de surface et les eaux souterraines. Cela a été réalisé à l’aide de divers outil tels qu’une étude du cycle hydrologique et un calcul de bilan, des profils débimétriques et physicochimiques du cours d’eau et un essai de traçage. [less ▲]

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See detailComparaison histologique et comportementale de différentes souches de souris après un épisode d’ischémie cérébrale
Fassotte, Ludivine ULg

Master's dissertation (2011)

L’ischémie cérébrale, qui correspond à une interruption du flux sanguin causée par l’obstruction d’une artère cérébrale, est occasionnée dans plus de 80% des AVCs humains. Cette maladie neurologique est ... [more ▼]

L’ischémie cérébrale, qui correspond à une interruption du flux sanguin causée par l’obstruction d’une artère cérébrale, est occasionnée dans plus de 80% des AVCs humains. Cette maladie neurologique est la seconde cause de mortalité dans les sociétés industrialisées et son impact est lourd sur les survivants. En effet, elle génère des déficits fonctionnels subsistant pendant des mois, voire des années. Ce travail s’inscrit dans la perspective de développement d’un traitement permettant une récupération fonctionnelle de ces déficits par la recherche de techniques permettant de mimer un AVC humain sur différentes souches de rongeurs. Le présent travail consiste en la mise en place d’une batterie de tests comportementaux permettant l’évaluation à court et à long terme des déficits sensorimoteurs, comportementaux et cognitifs causés par une ischémie cérébrale expérimentale de 30 minutes induite par la technique d’occlusion de l’artère cérébrale moyenne (MCAo) à droite. Dans cette perspective, deux souches murines couramment utilisées en laboratoire, 129S2/SvPas et C57Black6J ont été comparées. Une semaine puis trois semaines après l’opération, les capacités sensorimotrices des animaux sont évaluées à l’aide du rotarod, du pole test, du test d’agrippement tandis que l’activité locomotrice et l’anxiété sont mesurées dans un open field. Après un mois, l’endurance et la motivation sont testées par un programme de FR progressif alors que la flexibilité cognitive est évaluée à l’aide du programme du reversal learning. Au terme de l’évaluation comportementale, le cerveau des animaux est prélevé et l’étendue de la lésion cérébrale est évaluée à l’aide d’une révélation immunohistochimique utilisant le marquage anti-neuronal NeuN. Les résultats témoignent d’un effet significatif de l’ischémie chez la souche C57 sur les capacités sensorimotrices des animaux (rotarod et locomotion). Les résultats au FR progressif montrent qu’une ischémie de 30 minutes altère l’endurance des animaux lorsque le nombre d’appuis demandé est élevé. De même, un trouble des fonctions exécutives est également observé (passage d’un comportement à un autre). La lésion occasionnée par l’ischémie touche le striatum dorsolatéral chez les deux souches ainsi qu’une portion plus moins étendue du cortex cérébral dans le cas de la souche C57. L’étendue plus ou moins importante de la lésion est liée à l’anatomie vasculaire cérébrale qui est variable d’une souche à l’autre. Puisque le cortex moteur n’est pas affecté, les troubles observés sont probablement liés à la lésion du striatum, une portion du cerveau qui est étroitement connectée avec le cortex moteur. A l’issue de ces expériences, l’utilisation de la souche C57 semble être plus appropriée à l’étude de l’ischémie cérébrale transitoire chez la souris que la souche 129S2. Le présent travail montre que l’établissement d’une batterie de tests comportementaux sensibles à l’ischémie doit comporter à la fois des tests sensorimoteurs afin de déceler des troubles transitoires tels que la coordination motrice et l’endurance. Une telle batterie doit également comporter des tests cognitifs détectant des déficits subsistant à long terme tels que les troubles de la fonction exécutive. La sélection d’un modèle animal le plus approprié ainsi que la mise en place d’une telle batterie de tests permettront idéalement de corréler les déficits observés et les structures nerveuses impliquées dans les fonctions touchées par l’ischémie cérébrale. Dès que ces bases auront été posées, de nouveaux traitements appropriés pourront alors être testés. [less ▲]

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See detailModélisation d'évènements rares à l'aide de distributions non normales : application en finance avec la fonction sinh-arcsinh
Hambuckers, julien ULg

Master's dissertation (2011)

In 2008, the financial crisis put forward the relative inaccuracy of the market risk forecasting models in the financial industry. In particular, extreme events were shown to be regularly underestimated ... [more ▼]

In 2008, the financial crisis put forward the relative inaccuracy of the market risk forecasting models in the financial industry. In particular, extreme events were shown to be regularly underestimated. This problematic, initially developed in the seminal work of Mandelbrot (1963), is mainly due to financial models using the normal law while empirical evidence show strong leptokurticity in financial time series. This stylized effect is particularly damaging the forecasting of indicators like Value-at-Risk (VAR). In this study, we try to tackle problem by testing a newly-developed probability distribution, never used in finance: sinh-arcsinh function. By creating different datasets from non-parametric and GARCH models, we adjust common functions (normal, t location-scale, GED, gen. hyperbolic) and sinh-arcsinh function on the data. We show that, regarding the leptokurtic datasets extracted from the DJA and the NIKKEI 225, the sinh-arcsinh function performs a better adjustment than any other function tested. We also tested simple VAR models using normal laws, Student’s t or sinh-arcsinh functions, to assess the operational efficiency of the sinh-arcsinh function. We show that models using sinh-arcsinh functions provide more accurate and better in-sample and out-of-sample VAR forecasts than any other model using the normal laws. [less ▲]

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See detailArticle de régulation
Scheffers, Patricia ULg

Master's dissertation (2011)

Les outils pédagogiques (*) mis en place dans le cadre du cours d'atelier de projet d'architecture de 3e Bachelier sont-ils de nature à favoriser l’autonomisation de l'étudiant et à en rendre compte dans ... [more ▼]

Les outils pédagogiques (*) mis en place dans le cadre du cours d'atelier de projet d'architecture de 3e Bachelier sont-ils de nature à favoriser l’autonomisation de l'étudiant et à en rendre compte dans le cadre du développement de la compétence visée ? (*) Abstract, journal de bord, fiches d'auto-évaluation, plannings [less ▲]

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See detailEtude protéomique de l'incidence d'une hypertriglycéridémie sur le métabolisme hépatique de la souris
Ehx, Grégory ULg

Master's dissertation (2011)

L’hypertriglycéridémie est une pathologie largement répandue chez l’homme sédentarisé. Elle se définit comme un taux plasmatique de triglycérides (TAG) anormalement élevé (supérieur à 200 mg/dl). La ... [more ▼]

L’hypertriglycéridémie est une pathologie largement répandue chez l’homme sédentarisé. Elle se définit comme un taux plasmatique de triglycérides (TAG) anormalement élevé (supérieur à 200 mg/dl). La souris transgénique HuApoC-III est un animal modèle idéal pour l’étude de l’hypertriglycéridémie indépendamment des effets confondants qui y sont généralement associés (en particulier l’obésité et la résistance à l’insuline). En effet, elles sont hypertriglycéridémiques mais ne sont ni obèses ni résistantes à l’insuline. Dans la continuité d’une étude des adaptations mitoprotéomiques hépatique à une hypertriglycéridémie sévère (taux de TAG supérieur à 500 mg/dl) récemment menée par notre laboratoire, nous avons caractérisé par une technique de protéomique comparative, le 2DDIGE, les adaptations protéomiques de la membrane interne mitochondriale et du protéome cellulaire à ce même type d’hypertriglycéridémie, chez la souris HuApoC-III. Comme prédit lors de notre étude antérieure, le protéome de la membrane interne s’est avéré ne présenter aucune modification de sa composition entre les souris HuApoC-III et sauvages. Comme il a été rapporté que les souris HuApoC-III présentent une vitesse de respiration mitochondriale à l’état III sur succinate similaire à celle des souris sauvages, cette invariance de la composition protéique de la membrane interne pourrait refléter des altérations de sa composition lipidique ou de sa structure. L’analyse du protéome cellulaire total a permis de confirmer l’augmentation de la capacité du catabolisme des acides aminés et de la glycolyse suggérée par nos résultats antérieurs. Cette augmentation, accompagnée de l’augmentation de la capacité de la β- oxydation également décrite antérieurement, permettrait d’augmenter le taux de production d’acétyl-CoA, de glycérol-3-phosphate et d’ATP fin de supporter la production élevée de TAG des hépatocytes des souris HuApoC-III. Cette analyse a par ailleurs révélé que les hépatocytes des souris HuApoC-III présentent un stress oxydatif cytoplasmique, une probable accumulation de fer intracytoplasmique et une prolifération accrue. Ce stress oxydatif pouvant induire des lésions cellulaires et tissulaires ainsi que l’inflammation du foie, nous proposons que les souris HuApoC-III présentent une fibrose hépatique. [less ▲]

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See detailL’impact de la mobilité internationale sur le projet de carrière et la construction de l’identité professionnelle des cadres internationaux à la lumière des ancres de carrière et des typologies identitaires : Analyse comparative des motivations personnelles et professionnelles des cadres en mobilité internationale
Gérard, Julie ULg

Master's dissertation (2011)

Fondée sur une recherche empirique menée auprès de trente-trois cadres en situation de mobilité internationale, cette étude analyse l’impact de la mobilité internationale sur le projet de carrière et la ... [more ▼]

Fondée sur une recherche empirique menée auprès de trente-trois cadres en situation de mobilité internationale, cette étude analyse l’impact de la mobilité internationale sur le projet de carrière et la construction de l’identité professionnelle des cadres internationaux, en s’appuyant sur la théorie des ancres de carrière de Schein (1978, 1990) et la théorie des stratégies identitaires de Pierre (2003). Sur la base du récit de vie de ces trente-trois cadres, nous avons étudié leurs motivations personnelles et professionnelles afin de dresser une typologie nuancée et circonstanciée de leur stratégie d’identification. [less ▲]

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See detailContribution to the study on sound production in clownfishes (Perciformes, Pomacentridae): a multidisciplinary approach
Colleye, Orphal ULg

Doctoral thesis (2011)

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live ... [more ▼]

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Several studies have reported that vocalizations are associated with agonistic interactions but precise data are lacking and further investigations are needed. The nature of the sound-producing mechanisms also remained unresolved, only resting on few assumptions. Thereby, the main aim of the present thesis is (1) to determine the fundamental components of the acoustic communication in clownfishes, and (2) to explain the mechanisms of sound production. In order to achieve these objectives, the research has been divided into three different axes. Firstly, the study of the acoustic behaviors shows that no acoustic signal is associated with reproductive activities in clownfishes. Sound recordings during agonistic interactions indicate that these fishes produce two types of sounds. Aggressive sounds are produced during chases and threat displays while submissive (or head shaking) sounds are emitted in reaction to aggressive acts by dominant. Both types of sounds show size-related intraspecific differences in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger individuals, and inversely. Consequently, these sonic features might be useful cues for individual recognition and maintenance of cohesion within the group. Secondly, the study of the sound-producing mechanism highlights that aggressive sounds are initiated by buccal jaw teeth snapping caused by rapid mouth closure attributed to a sonic ligament. It appears that the swimbladder does not function as a resonator that amplifies and changes the quality of sounds. This structure is a highly damped sound source prevented from prolonged resonant vibrations. On the other hand, the rib cage might be the major acoustic radiator and its resonant properties might explain the size-related variations observed in pulse duration and dominant frequency. Thirdly, the comparison of aggressive sounds among fourteen clownfish species indicates that the same relationship between fish size and both dominant frequency and pulse duration is spread over the entire group (i.e. tribe Amphiprionini). These results highlight all species use a highly conservative mechanism of vocalization. Pulse period appears to be the most variable acoustic feature and could be involved in species-specific recognition, as well as pulse duration and dominant frequency in a lesser extent through their relationship with body size. Although sound production appears to be restricted to some agonistic behaviors, these sounds seem to constitute an integral part of the peculiar way of life of clownfishes. The aggressive and submissive sounds would also result from two different mechanisms.   [less ▲]

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See detailREGULATION DE L'EXPRESSION ET DE LA REPLICATION DU VIRUS T-LYMPHOTROPE HUMAIN DE TYPE I (HTLV-1) PAR LE COMPLEXE MINICHROMOSOME MAINTENANCE 2-7 (MCM2-7)
Barez, Pierre-Yves ULg

Master's dissertation (2011)

First human retrovirus discovered, HTLV-1 infects approximately 20 million individuals worldwide. HTLV-1 is the etiological agent of adult T-cell leukemia and a neurodegenerative disorder called HAM/TSP ... [more ▼]

First human retrovirus discovered, HTLV-1 infects approximately 20 million individuals worldwide. HTLV-1 is the etiological agent of adult T-cell leukemia and a neurodegenerative disorder called HAM/TSP (HTLV-1 associated myelopathy/Tropical spastic paraparesis). The MCM2-7 complex seems to play a key role in the biology of viruses, such as EBV (Epstein-Barr virus), KSHV (Kaposi’s sarcoma associated virus) or Influenza. This is also the case for HTLV-1 virus because we revealed the recruitment of MCM2-7 onto the viral promoter. The role of this interaction does not pertain to viral replication but is involved in transcriptional regulation. In fact, overexpression of MCM3 increases Tax transactivation activity dependently on Tax/MCM3 interaction and MCM3 carboxy-terminal domain. Finally, our observations indicate that MCM3 is likely required for Tax nuclear shuttling. This work thus gives insights into new mechanisms by which Tax ensures the viral persistence and leads to the development of HTLV-1 associated diseases. [less ▲]

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See detailRôles des hydrocarbures dans le comportement agrégatif de la coccinelle asiatique, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Fassotte, Bérénice ULg

Master's dissertation (2011)

In order to protect themselves against cold and to survive through the winter, the Asian ladybeetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) forms large aggregates inside dwellings to ... [more ▼]

In order to protect themselves against cold and to survive through the winter, the Asian ladybeetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) forms large aggregates inside dwellings to overwinter. In this work, the implication of hydrocarbons on the aggregative behaviour of this invasive species has been examined to understand the mechanisms involved in this particular phenomenon. The evolution of non-volatile compounds, proved to be used by H. axyridis in this phenomenon, on one hand to guide individuals to the aggregate ("trail") and on the other hand, to ensure the cohesion of the cluster ("aggregation blend"), has been studied by performing chromatographic analyses and behavioural tests. The results show that the composition of the trail deposited by individuals, and its biological activity on ladybirds, change over months. However, the change in ladybirds’ response towards these trails is not due to a modification of blend attractiveness but well to a change in the physiological state of ladybugs. Furthermore, the effect of photoperiod on the induction of that hivernation state was tested. It was highlighted that only a short photoperiod could not be responsible for the aggregation state of H. axyridis. Then, the maturing process of the aggregation blend was studied, demonstrating that saturated hydrocarbons were more persistent and suggesting their use by ladybirds to join the same aggregation sites year after year. Moreover, it turned out that cuticular hydrocarbons, as well as thigmotaxis, play a role in the aggregation behaviour of H. axyridis. However, this second factor is involved to a lesser extent. [less ▲]

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See detailContribution à la conservation de la flore cupro-cobalticole endémique du Katanga (R.D.C.) : Conservation en banque de graines et régénération d'espèces métallicoles
Boisson, Sylvain ULg

Master's dissertation (2011)

Metallophytes are plants that represent the biodiversity of metal-rich soils. Some of them are able to accumulate high metal concentrations: metal hyperaccumulators plants. In Katanga (RD Congo), 32 ... [more ▼]

Metallophytes are plants that represent the biodiversity of metal-rich soils. Some of them are able to accumulate high metal concentrations: metal hyperaccumulators plants. In Katanga (RD Congo), 32 species have been identified as copper-cobalt endemic but mining activities are still a threat to outcrop ecosystems. We must characterize native environmental parameters (realized niche) and the full range of environmental conditions in culture (fundamental niche) to conserve, preserve and restore these ecosystems. Six representative species of the natural copper gradient were selected after soil-species data analyses (Crepidorhopalon perennis, Crotalaria cobalticola, Gladiolus ledoctei, Haumaniastrum robertii, Lopholaena deltombei and Sopubia mannii). The study determined their behavior (germination, survival) and their development (vegetative measures) on one group of natural soil (from three copper gradients of Fungurume V hill), two groups of artificially contaminated soils with incremental doses (copper sulfate and copper hydroxycarbonate: 500, 2000 and 5000 mg.kg-1) and one uncontaminated soil (control) by two types of plant establishment (direct seeding and transplant from Petri dishes). The results depend on species habitat and show that four of these species can grow on uncontaminated soil in the early stages of growth. In addition, the seed bank (in Faculty of Agronomy - University of Lubumbashi) management (cleaning, updating and germination tests of accessions) was maintained using standard methods. The results of germination tests demonstrated the effectiveness of some conservation methods and helped to provide recommendations for the methodology. [less ▲]

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See detailMise en place de différentes stratégies visant à favoriser l’approche « push-pull » pour le contrôle des pucerons en cultures maraîchères dans l’est de la Chine
Chevalier Mendes Lopes, Thomas ULg

Master's dissertation (2011)

The Chinese farmers apply a lot of pesticides in their vegetable crops. This situation, due to the socio-economic context of the rural population of the country, affects the food security. This work aims ... [more ▼]

The Chinese farmers apply a lot of pesticides in their vegetable crops. This situation, due to the socio-economic context of the rural population of the country, affects the food security. This work aims to study alternatives to the intensive use of synthetic pesticides, namely by the establishment of “push-pull” strategies, in courgettes and potato fields. We used three semiochemicals, the (E)-β-farnésène, the (Z)-3-Hexenyl acetate and a garlic extract and intercropping with pea. The effect of these treatments in the populations of aphidiphagous beneficial insects was determined by five weeks of insect trapping and observations on the plants. The results indicate that none of the modalities has a significant effect on the populations of beneficial insects and aphids. However, we observed some trends, especially with the (E)-β-farnésène in the courgettes fields. In addition, information sheets were made to inform and raise awareness of the Chinese farmers about the use of pesticides and the role of beneficial insects in the control of aphid populations. [less ▲]

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See detailLa place de l'identité dans la politique étrangère. Le cas de la Turquie dans la période de pos-11 septembre 2001
Arslan, Nevzat ULg

Doctoral thesis (2011)

Il est question, dans ce travail, de découvrir les variables qui jouent un rôle dans l'orientation et dans la détermination de la politique étrangère turque. Il s'agit donc de s'intéresser aux variables ... [more ▼]

Il est question, dans ce travail, de découvrir les variables qui jouent un rôle dans l'orientation et dans la détermination de la politique étrangère turque. Il s'agit donc de s'intéresser aux variables causales découlant de la politique intérieure de la Turquie. Ainsi est évaluée l'importance des variables individuelles, institutionnelles, gouvernementales et systémiques dans la détermination des idées et des intérêts défendus par les différents acteurs internes. Adoptant une approche constructiviste des relations internationales, cette étude consiste, d'une part, en une description de l'identité nationale de l'État turc et de l'autre en une explication de la redéfinition de cette identité par une nouvelle idéologie, défendue par une nouvelle classe dirigeante. Nous nous sommes penchés sur les valeurs et les identités nationales qui ont contribué à façonner les conceptions et les priorités de la politique étrangère turque. Ainsi, l'approche théorique choisie doit tenir compte de ces divers facteurs, qui exercent une influence sur la formulation des intérêts nationaux. [less ▲]

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See detailContribution à la recherche et à l’étude d’améliorants de panification
Dubrowski, Thomas ULg

Master's dissertation (2011)

This work takes place in the current trend aiming to find new substances that, once added to the formulation of bread, improve its characteristics. To do this, a homologous series of three emulsifiers ... [more ▼]

This work takes place in the current trend aiming to find new substances that, once added to the formulation of bread, improve its characteristics. To do this, a homologous series of three emulsifiers, synthesized from glucuronic acid on which were grafted hydrocarbon chains of different lengths (from 14 to 18 carbon atoms), was obtained by glycosylation. The purification of these three surfactants is also described as feasible, with an almost complete separation of the two anomers obtained through this synthesis. Then these three synthesized products were applied to bakery by conducting laboratory tests (farinograph, alveograph) followed by micropanification tests in real conditions. In order to compare their results, two commercial references (DATEM and SSL) have also been used. It appears that none of the alkyl glucuronolactone possesses a “dough strengthener” effect while a “crumb softener” effect was noted (P < 0.05) for GlcA-O-C14 and -C16 in comparison with the “control”, with in the latter case, a greater decrease of firmness than with SSL, already popular for its action. The role of these molecules on staling was also analyzed and it seems that they slow down the hardening of bread after 27 h (P < 0.05) more than the commercial references, whereas after 48 h, only GlcA-O-C18 retains an advantage against the formulation without any emulsifier, even if it is no longer significant. [less ▲]

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See detailDa Alessandro ai Theoi Adelphoi. Fondazione e legittimazione della dinastia tolemaica, tra IV e III secolo a.C.
Caneva, Stefano ULg

Doctoral thesis (2011)

The research focuses on the first century of the Macedonian rule over Egypt in order to study how the Ptolemies had their power legitimated in Africa and in the broader Mediterranean context. Literary ... [more ▼]

The research focuses on the first century of the Macedonian rule over Egypt in order to study how the Ptolemies had their power legitimated in Africa and in the broader Mediterranean context. Literary sources (both prose and verse, in Greek and Egyptian language), inscriptions, papyri, and iconography are used to set an interdisciplinary approach to the topic. Major attention is paid to the social contexts where ideological motifs originate and spread; to the link between media, genres and consensus making; to the genealogy and development of specific legitimating themes and their later incorporation in learned traditions or local identities. Section I: From Alexander to the Ptolemies. Chapter I: Alexander in Egypt: focus is on the role of Siwah in the perspective of the Greek, Macedonian, and Egyptian legitimation of Alexander's power in Egypt; particular attention is paid to how legitimating traditions are used and reshaped to the purposes of broadening the limits of Macedonian kingship, depicting Alexander as a Greek hero, interpreting Egyptian kingship for Greeks and Macedonians and naturalizing Alexander as a Pharaoh. Chapter II: In the name of Alexander: how Ptolemy adapted to the hierarchy of proximity to the king to legitimate his power in Egypt and finally to establish a new dinasty; main topics are the use of Alexander's body in the historical context of the succession and in the local tradition of Alexandria; the historical events of the last decades of IV century are considered from the perspective of the development of legitimating themes, such as the political allegiance to Alexander, the right of conquest, the use of marriage diplomacy. Section II: The Political Use of Religious Festivals under Ptolemy II. Chapter III: Sources and Historical Problems concerning the Ptolemaia: sources on the Ptolemaia, Pentaeteris and Callixeinus' report in Athen. V are discussed to study dynastic festivals during Ptolemy II’s reing. Chapter IV: Anatomy of a Festival: The Grand Procession of Ptolemy II: focus is on the making of an historical and mythic legitimating past through the scenes in the procession. Section III: Patterns of Female Power: The Case of Arsinoe II Chapter V: Shaping Female Power: Arsinoe II as a Queen: Arsinoe II's career and political legacy are discussed to offer a gender-related evaluation of her role as a queen in both Greco-Macedonian and Egyptian traditions. Chapter VI: Female Ruler Cults. Arsinoe in Early Hellenistic Context: the analysis combines court poetry, iconography and documentary texts to study the cults for Arsinoe both as a member of the Theoi Adelphoi and as an individual goddess, the Philadelphos. Arsinoe's case is then discussed in the broader perspective of female ruler cults in early Hellenism. [less ▲]

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See detailCaracterización del producto cerámico en las comunidades neolíticas de mediados del V milenio Cal BC: El valle del Éufrates y el valle del Khabur en el Halaf final (Siria).
Gomez Bach, Ana Maria ULg

Doctoral thesis (2011)

The characterization of pottery production in the mid-sixt millennium cal BC in Neolithic communities: the Euphrates valley and Khabur basin in Late Halaf. SUMMARY The characterization of pottery ... [more ▼]

The characterization of pottery production in the mid-sixt millennium cal BC in Neolithic communities: the Euphrates valley and Khabur basin in Late Halaf. SUMMARY The characterization of pottery production in the mid-sixth millennium cal BC contexts in the Middle East arises from the need to understand how consolidated agricultural and pastoral communities of the Fertile Crescent were structured and organized. This chrono cultural period is embodied in an archaeological record of great interest in order to identify the different economic, social and symbolic responses at the final moment of the so-called Halaf culture. The opportunity to study the pottery assemblages from two sites and two regions, such as the Euphrates valley and the valley of Khabur, with new material from Tell Halula (16,668 sherds) and Chagar Bazar (21,194 sherds), allowed us to study and apply the same methodology to both sets from the very beginning of fieldwork. The analysis of 37,882 fragments from a comprehensive perspective and by using archaeometric techniques (chemical, petrographic and PIXE analysis) as well as morphometric and basic techno functional characterization analysis set new guidelines on the archaeological potential of these sets. Drawn up from Archaeology and Materials Science, this contribution has its methodological framework focused on rebuilding the chaîne operatoire. This reconstruction has allowed us to study and isolate two assemblages and to outline the existence of different socio economic practices, some of which had clear regional links and a strong substrate, but above all with basic subsistence practices which can be addressed from the ceramic product itself. Likewise, the specific chronological framework provided by new radiocarbon dates of both sites, which are between 5600-5300 cal BC, enables not only to characterise these productions but also to arise new questions to understand the interaction mechanisms between communities; mechanisms that cover from basic subsistence practices, i.e. the handling and processing of food and products, to mechanisms which regulate and structure the group. [less ▲]

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See detailDifférenciations sociospatiales et gouvernance municipale dans les banlieues de Beyrouth : à travers l'exemple de Sahel AlMatn AlJanoubi et des municipalités de Chiyah, Ghobeiri et Furn AlChebbak
Farah, Jihad ULg

Doctoral thesis (2011)

La thèse s’inscrit dans le débat sur une des “grandes questions urbaines contemporaines”: comment dans la multiplication des projets individuels et collectifs de plus en plus fragmentés se construit la ... [more ▼]

La thèse s’inscrit dans le débat sur une des “grandes questions urbaines contemporaines”: comment dans la multiplication des projets individuels et collectifs de plus en plus fragmentés se construit la ville d’aujourd’hui? Dans un contexte d’étalement urbain continu et de crise des “grands récits” de la modernité, l’individu comme le groupe connaît de plus en plus de difficultés à trouver sa place, son “lieu”, en ville. La recherche de l’entre-soi et l’altérité devient de plus en plus importante dans cette quête. La thèse revient sur les différents concepts traitant des différenciations sociospatiales en ville (ségrégation, marginalisation, relégation, fragmentation). Elle remarque que ces concepts favorisent une lecture systémique de la réalité urbaine où les éléments factoriels économiques, culturels et politiques ont un rôle central dans l’explication. Tout en se mettant dans la continuité de ces travaux, la thèse privilégie une lecture se basant sur trois entrées: - La crise de citoyenneté urbaine (crise de définitions de la ville, de ses limites, de ses citoyens, de leurs droits et surtout de sa gouvernance) comme principale grille explicative - Le local. Ce dernier étant d’une part l’échelle où ces différenciations sociospatiales sont les plus manifestes, et d’autre part car c’est à cette échelle que les phénomènes systémiques doivent se “redéfinir” en s’inscrivant dans le contexte. - Les périphéries et les banlieues où la cirse de citoyenneté est plus nette et où les acteurs locaux – dans un milieu à la recherche de sens, et en continuelle redéfinition – cherchent à avoir plus d’emprise sur leur milieu direct. Dans ce contexte la thèse avance que les spécificités du local, notamment la gouvernance locale et la spécialisation économique ont un poids déterminant dans la définition des dynamiques territoriales et par suite des différenciations sociospatiales. Cette hypothèse est déclinée en deux hypothèses opérationnelles: 1. - L’une s’inscrivant dans une perspective historique: Si incontestablement des dynamiques induites de la globalisation affectent les différenciations sociospatiales dans l’espace beyrouthin, nous pensons que l’héritage d’un temps long dans ses dimensions politiques et économiques pèse encore fortement sur ces différenciations dans les banlieues de Beyrouth. 2. L’autre dans une perspective politique: La stabilisation du régime municipal est aujourd’hui la rationalité qui domine l’action municipale. Elle est déterminante de la gouvernance locale dans chaque commune et par suite consubstantielle de l’évolution des différenciations sociospatiales dans ces banlieues. Les banlieues de Beyrouth, considérées comme cas révélateur, sont retenues pour comme terrain d’étude Deux méthodes d’analyse complémentaires sont mobilisées. L’une dite diachronique essaie de repérer les constantes et les variables dans l’histoire d’un district de ces banlieues comprenant les actuelles banlieues sud et sud-est, en insistant sur les rôles particuliers de la gouvernance et de l’économie. L’autre dite synchronique tente de souligner des liens entre des typologies de gouvernance urbaine différentes et leurs impacts en termes de différenciations sociospatiales en mobilisant le concept de régimes urbains. Les principales conclusions sont: - Des arrière-pays consolidés, avant l’étalement des villes centres, ayant leurs propres dynamiques: leur urbanisation, leurs économies et leurs gouvernances locale, leurs trajectoires propres connaissent très tôt la fragmentation urbaine (conclusion en porte-à-faux par rapport au corpus de la fragmentation soulignant le rôle fondateur de la globalisation) - L’architecture du régime urbain local et sa recherche de stabilité interne affectent fortement l’articulation de l’échelle d’action locale aux échelles d’action supérieures. Comme elles affectent certaines formes de dynamiques territoriales locales (notamment celles inscrites dans le registre de construction identitaire des territoires). Toutefois elles semblent avoir moins d’impact sur les aspects centralités et flux des dynamiques territoriales. - La fragmentation politique du territoire peut s’avérer une ressource importante pour les acteurs locaux pour négocier et s’approprier une place, un “lieu” dans les agglomérations urbaines d’aujourd’hui. D’autre part, devant la pression continue que connaissent les territoires urbains des périphéries pour se redéfinir et s’articuler à de nouvelles entités sociospatiales en formation, on peut observer dans certains cas de la véritable innovation en termes de politiques urbaines. Ces municipalités peuvent représenter, comme dans le cas de certaines dans les banlieues de Beyrouth, des laboratoires qui font émerger des nouveaux outils urbains qui pourront servir pour penser et gérer la ville à d’autres échelles. [less ▲]

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See detailDes loups dans la Cité. Eléments d'écologie pragmatiste
Doré, Antoine ULg

Doctoral thesis (2011)

Les politiques contemporaines sont marquées par des bouleversements écologiques qui interrogent la place à accorder à une liste toujours plus longue et hétérogène de prétendants à la vie publique. Cette ... [more ▼]

Les politiques contemporaines sont marquées par des bouleversements écologiques qui interrogent la place à accorder à une liste toujours plus longue et hétérogène de prétendants à la vie publique. Cette thèse propose un examen empirique d’une telle dynamique à partir du cas de la mise en politique des loups en France. En traçant les multiples manières dont les loups interpellent ceux et ce qui les entourent, en décrivant les agencements hybrides d’humains et de non-humains qu’ils forment et transforment sur leur passage et en prêtant attention aux différentes manières dont les acteurs affectés prennent en charge les situations générées par ces animaux, il s’agit d’identifier et de suivre, pas à pas, des portions importantes de quelques-unes des trajectoires qui composent la carrière politique des loups. Cette recherche montre alors comment des scientifiques, des juristes, des publics, des représentants de l’État, des journalistes, etc., mais aussi les loups eux-mêmes, composent ces trajectoires spécifiques marquées par des pratiques, des temporalités, des spatialités, des matérialités particulières. L’analyse révèle comment la présence publique des loups est instaurée par la science, le droit, l’État, etc. Elle rend compte également réciproquement de la manière dont la science, le droit, l’État, etc., s’inventent et se transforment à travers les loups. Cette thèse propose finalement un compte rendu synthétique et réaliste des modalités de construction d’une politique des loups et vise à éclairer deux questions plus générales : dans quel sens peut-on parler des implications politiques de la nature et en quoi cela nous invite-t-il à changer nos habitudes de description et d’aménagement de la vie ensemble ? [less ▲]

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See detailAnalyse comparative de différentes démarches de modélisation hydrologiques pour la représentation de la couverture forestière dans le bassin versant de la Houille (Contribution au projet INTERREG : P2IH)
Deraedt, Deborah ULg

Master's dissertation (2011)

The more simplistic models often overlook the representation of forest cover. Nevertheless it has a significant impact with water uptakes that follows a seasonal variation for example. The comparison of ... [more ▼]

The more simplistic models often overlook the representation of forest cover. Nevertheless it has a significant impact with water uptakes that follows a seasonal variation for example. The comparison of the two global models, PDM and GR4J, highlights the poor quality of simulation on the wooded watershed of the Houille (Belgium). In the case of PDM results are disappointing both in calibration and in validation. The Nash criteria are 0.65 and 0.52 respectively. Calibration of GR4J was a little more promising. But the validation has proved the weakness of the model to simulate the peaks coming from melting snow. The Nash coefficients go down from 0.81 to 0.65. We have tested the EPIC model with the plant parameters recommended for SWAT (which uses the same plant growth module) for spruce and oak. The parameters characterizing the soil are adjusted to the water content values obtained on two measurement sites. One is located in a spruce stand and the other in an oak stand. The comparison of the EPIC model simulation, as describes before, and in situ measurements shows an important difference in terms of water uptake. The model tends to overestimate trees water consumption. It proves the importance of using proper plant parameters to remain representative of the site dynamics and on larger scale, of the watershed dynamics. [less ▲]

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See detailClassification automatique d'images biologiques par variantes d'arbres de décision
Mathéi, Axel ULg

Master's dissertation (2011)

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See detailPrédiction de structures de macromolécules par apprentissage automatique
Marcos Alvarez, Alejandro ULg

Master's dissertation (2011)

Proteins are an essential constituent of cellular life whose biggest part of their function is determined by their tridimensional shape. Nowadays, however, no method is able to predict efficiently ... [more ▼]

Proteins are an essential constituent of cellular life whose biggest part of their function is determined by their tridimensional shape. Nowadays, however, no method is able to predict efficiently tridimensional protein structures based only on their amino acids sequence. We propose here an "ab initio" approach based on the concept of learning for search. Protein structure prediction is modeled in the form of an optimization problem solved by an optimization algorithm that follows an iterative framework in which a structure modification operator is selected and then applied to the current structure. The quality of the new structure is then assessed by an oracle that will determine whether or not the structure is accepted. The repetition of this framework will eventually lead to the sought structure. The critical point of this rationale lies in the choice of the modification operator, which has to be done very accurately in order to avoid the classical pitfalls of optimization problems. The operator selection step will then be subjected to machine learning thus legitimizing the term "learning for search" of the proposed method. The goal of this thesis is to show that machine learning can improve the results obtained via a simple optimization procedure. Our experiments show that this goal is fulfilled. We however know that many choices that we did should be questioned regarding both the optimization and the machine learning procedures. Finally, we can notice that the application domain of this work extends beyond the protein structure prediction problem. There exist indeed many optimization problems in the scientific literature for which no exact neither approximation algorithm exists and that are thus still very badly solved. Such problems could greatly benefit from a "learning for search" approach such as the one described in this work. [less ▲]

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See detailStockage géologique du CO2: l'étanchéité des puits
Dieudonné, Anne-Catherine ULg

Master's dissertation (2011)

Carbon capture and storage is an innovator approach to fight climate changes through the reduction of greenhouse gas emissions. Abandoned coal mines are currently less studied than other reservoirs but ... [more ▼]

Carbon capture and storage is an innovator approach to fight climate changes through the reduction of greenhouse gas emissions. Abandoned coal mines are currently less studied than other reservoirs but could also be used for the storage of carbon dioxide. However the problem of shaft sealing appears to be central as far as the safety, economic, ecologic and health stakes of geological storage are concerned. The purpose of the present work is the study of shaft sealing in the framework of CO2 storage projects. More precisely the problem consists in the numerical study, with the LAGAMINE finite elements code, of gas transfers around a shaft seal system. A coupled hydro-mechanical model of unsaturated geomaterials is presented. The response of the flow model is first studied through a simple synthetic problem simulating the injection of gas in a concrete-made column. It stands out of this first modeling that the advection of the gas phase represents the main transfer mechanism of CO2 in highly unsaturated materials. Furthermore the setting of a bentonite barrier seal allows limiting considerably gas influx to the biosphere. A 2D axisymetric hydromechanical modeling of the Anderlues natural gas storage site is then performed. The design of the shaft seal system appears to be a determinant element to evaluate the risks of CO2 leakage. [less ▲]

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See detailDark atoms : properties and observational consequences
Wallemacq, Quentin ULg

Master's dissertation (2011)

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See detailGéologie appliquée au développement des nouvelles découvertes et aux nouveaux thèmes d’Exploration «Shale Gas Silurien» du Bassin de Berkine (Ghadamès, Algérie)
Djouder, Hocine ULg

Master's dissertation (2011)

Durant de nombreuses années, les compagnies opérant au sein du Bassin de Berkine se sont focalisées sur les Formations gréseuses du Cambro-Ordovicien dans la partie Ouest, du Dévonien inférieur et du ... [more ▼]

Durant de nombreuses années, les compagnies opérant au sein du Bassin de Berkine se sont focalisées sur les Formations gréseuses du Cambro-Ordovicien dans la partie Ouest, du Dévonien inférieur et du Carbonifère dans le centre du bassin, ainsi que dans les séries triasiques sus-jacentes. Le Silurien était considéré comme un objectif secondaire puisque sa qualité de réservoir était négligée au profit de son potentiel de « roche mère ». En effet, la roche mère principale pour les réservoirs paléozoïques est issue des argiles radioactives siluriennes de base « hot shales » rencontrées à plus de 6000 m en profondeur. Le Bassin de Berkine, localisé dans le Sahara Oriental algérien, s‘étend sur près de 102 000 km². Au Paléozoïque inférieur, cette vaste étendue géographique était le siège d‘une sédimentation silicoclastique intracratonique puissant. Les sédiments siluriens se sont alors déposés dans un contexte d‘élévation globale du niveau marin relatif lié à la déglaciation tardi-ordovicienne. Les flux terrigènes prenaient alors leur source au sud du bassin, vers le Môle de Tihemboka et le Hoggar alors en surrection. Deux zones sièges d‘une intense subsidence, le secteur de Menzel Lejmat et le Sillon de Marfag, présentent la série sédimentaire silurienne au complet. Deux entités sont alors mis en évidence, (I) les argiles principales (AP) à graptolites, et (II) les alternances gréso-argileuses (AGA) auxquelles sont rattachées les ensembles réservoirs M, A et B. Ces entités sont composées de 5 séquences principales (Si-1, Si-2, Si-3, Si-4 et Si-5), allant du Llandoverien au Pridolien, mises en évidence dans le système silurien du Bassin de Berkine. Ce découpage est le résultat d‘une analyse séquentielle haute résolution de deux coupes types (Puits MLEP-1 et BRD-5) basée sur l‘enchainement vertical des séquences sur diagraphies et carottes, ainsi que sur les travaux menés dans toute la Synéclise de Ghadamès. Les séquences Si-1 et Si-2 sont datées du Llandoverien. Au cours de cette période, le bassin était le siège d‘une importante sédimentation argileuse de « Hot Shales » et d‘Argiles à Graptolites de 500 à 650 m d‘épaisseur. Ces faciès argileux de plateforme externe profonde passent au sommet à des faciès carbonatés très vite succédés par des sédiments gréseux de l‘unité M1 initiateurs d‘un contexte deltaïque progradant. D‘un point de vue géodynamique, ces deux séquences se rattachent au stade d‘initiation. La séquence Si-3, datée du Wenlockien, atteint 150 m d‘épaisseur. Les sédiments qui la composent se sont déposés dans un contexte marin littoral dominé par un régime tidal transgressif très développé dans cet Ensemble réservoir A. Cet environnement devenant de plus en plus marin vers le sommet de la séquence, avec un dépôt de 50 m d‘argiles litées, s‘achève par une limite de séquence SB4 qui se matérialise au sud du bassin par une surface d‘altération à ciment sidéritique. Le Bassin de Berkine passe alors au stade de maturité avec le dépôt des unités réservoirs A1 et A2. Les séquences Si-4 et Si-5 sont d‘âge Ludovien et Pridolien. Durant cette période, le régime deltaïque a envahi toute l‘aire de sédimentation, passant par un régime progradant du sud-est vers le nord-ouest pour l‘unité B1, à un environnement progressivement fluvio-lacustre pour l‘unité B2. Par la suite, l‘installation définitive des grès massifs du Dévonien en discordance sur le Silurien marque le comblement du bassin et sa sénescence. Cette étude souligne le potentiel réservoir des unités argilo-gréseuses du Silurien terminal du Bassin de Berkine qui est clairement identifié dans des séquences deltaïques progradantes dans lesquelles les processus tidaux peuvent s‘exprimer. Cela suggère aussi des distributions complexes des objets réservoir et de leurs hétérogénités réservoir qui restent à investiguer. [less ▲]

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See detailAlternative strategies for aphid biological control: special regard on honeydew and bacteria from aphids
Leroy, Pascal ULg

Doctoral thesis (2011)

Aphids constitute a scourge in agriculture and are a major problem for crops worldwide. By feeding on the phloem sap but also by injecting saliva and viruses in plant tissues, they cause a weakening and ... [more ▼]

Aphids constitute a scourge in agriculture and are a major problem for crops worldwide. By feeding on the phloem sap but also by injecting saliva and viruses in plant tissues, they cause a weakening and impair the growth of the host-plant. Moreover, honeydew, the aphid excretory product, reduces transpiration and photosynthesis. But honeydew also attracts many predators and parasitoids of aphids, playing a key role in tritrophic interactions between plants, pests and beneficial insects. In this context, the main objective of this thesis was to promote the use of the hoverfly Episyrphus balteatus (De Geer) (Diptera: Syrphidae) as an efficient biological control agent in aphid management strategies. Two different approaches have been developed here with success: (1) the introduction of this auxiliary in the fields or under greenhouses, using a biological control device developed in this work and (2) the attraction, the retention and the oviposition stimulation of the populations naturally present or manually introduced in the fields. To achieve these objectives, special attentions were focused on the aphid honeydew that is abundant on aphid infested plants, with special attention to the bacteria present in this aphid secretion. First, our studies allowed determining that honeydew acts as a volatile and a contact kairomone both for the E. balteatus larvae and adults but also on the Asian coccinellid Harmonia axyridis (Pallas) helping these aphidophagous predators to locate prey. In a second time, using semiochemicals from plants [(Z)-3-hexenol, R-(+)-limonene] and aphids [E-(β)-farnesene] but also crude and artificial honeydew, the hoverfly oviposition was artificially induced (without plants or aphids) on an inert surface. The so obtained eggs were then introduced in field crops to regulate aphid populations (biological control device). Then, the volatile compounds associated with honeydew were identified and tested as potential attractants and ovipositional stimulants: an artificial honeydew as well as an attractive formulation were composed and successfully tested in field crops since they both increased the presence of auxiliaries in targeted areas. Finally, the interaction between the host plant and aphids was envisaged to determine whether aphids are able to modify the host plant amino acid content in order to ingest sufficient nitrogen for growth: this study highlighted that the proportions of glutamine and asparagine significantly increase in the phloem sap when plants are infested. [less ▲]

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See detailSur les ensembles paradoxaux : de Banach-Tarski à Dougherty-Foreman
Kleyntssens, Thomas ULg

Master's dissertation (2011)

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See detailImprimeurs et société dans les Pays-Bas méridionaux et en principauté de Liège (1473-ca 1520)
Adam, Renaud ULg

Doctoral thesis (2011)

La thématique placée au centre de cette dissertation doctorale pourrait se résumer à cette question : comment les premiers imprimeurs se sont intégrés au tissu socio-économique des Pays-Bas méridionaux et ... [more ▼]

La thématique placée au centre de cette dissertation doctorale pourrait se résumer à cette question : comment les premiers imprimeurs se sont intégrés au tissu socio-économique des Pays-Bas méridionaux et de la principauté de Liège aux tournants des XVe et XVIe siècles ? Cette étude a été structurée autour de trois axes. La vétusté des synthèses sur le sujet et l’évolution constante de la recherche ont rapidement imposé la nécessité de réécrire en premier lieu un historique détaillé, ville par ville, de l’introduction de l’art typographique et de son évolution jusqu’en 1520. Les regards se sont ensuite portés sur le métier d’imprimeur avec des questionnements centrés sur le statut juridique et l’organisation de cette profession, sur le fonctionnement interne d’une imprimerie ainsi que sur la commercialisation des livres et le profil de la clientèle. Les résultats de la dernière partie sont le fruit d’une investigation dans la composition de la communauté typographique et d’une tentative de décorticage des trames réticulaires nouées avec les autres acteurs de la société urbaine. [less ▲]

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See detailEvidence for a role of microRNA-21 and microRNA-125b in negatively regulating angiogenic processes
Malvaux, Ludovic ULg

Doctoral thesis (2011)

Recently discovered, miRNAs have quickly become strong regulators of biological processes. These small non-coding RNAs of about 22 nucleotides partially base pair to the 3’UTR of the targeted mRNAs and ... [more ▼]

Recently discovered, miRNAs have quickly become strong regulators of biological processes. These small non-coding RNAs of about 22 nucleotides partially base pair to the 3’UTR of the targeted mRNAs and repress them. Due to their wide range effects, microRNAs were extensively studied in various diseases and were rapidly demonstrated to be deregulated in pathologies such as cancer. More recently, they have been shown to be implicated in vascular network formation (angiogenesis) and were proposed to be used in anti-angiogenic therapies. Nowadays about twenty angiomiRs have been discovered including the endothelial specific miR-126. As observed in several miRNA profiling of endothelial cells and confirmed in our laboratory in HUVECs (human umbilical veins endothelial cells), miR-21 and miR- 125b are highly expressed in this cell type suggesting that these miRNAs could play a role in vascular network formation. We then studied the implication of miR-21 and miR-125b in in vitro as well as in vivo angiogenesis. One of the most studied miRNA in cancer progression is miR-21 as it was shown to modify proliferating properties of numerous tumor cells. Our experiments revealed that miR-21 overexpression and inhibition have no direct effect on endothelial cells proliferation rate. However, miR-21 overexpression leads to the inhibition of HUVECs migration and tube formation as demonstrated in in vitro angiogenic assays. Moreover, opposite effects were observed upon miR-21 inhibition. We also confirmed that RhoB, a small Rho-GTPase implicated in stress fibers formation, is involved in these phenomena as RhoB inhibition using siRNA mimics miR-21 overexpression in endothelial cells. Moreover, miR-21 modulation affects RhoB mRNA and protein expressions. We further demonstrated a direct interaction between miR-21 and the RhoB 3’UTR confirming that miR-21 modulates angiogenesis partially through its effect on RhoB expression. A similar approach was used to study the implication of miR-125b in vascular network formation. In vivo, miR-125b expression was modulated in the zebrafish revealing that miR-125b expression needs to be controlled for proper intersomitic blood vessels establishment. In vitro, miR-125b overexpression decreases HUVECs migration and tube formation whereas miR-125b inhibition increases these functions. A transcriptomic analysis suggests that numerous adhesion molecules such as VE-cadherin or MCAM are involved in these processes. Furthermore, other proteins known to regulate angiogenesis such as the transcription factor ETS1 and the VEGFA receptor, VEGFR2 were also shown to be regulated by miR-125b. This observation confirms that miR-125b modulates angiogenic properties of endothelial cells. Finally, we investigated the impact of miR-21 and miR-125b overexpression in an in vivo pathological model of angiogenesis. In a mouse model of choroïdal neovascularization we demonstrated that miR-21 or miR-125b overexpression in the eyes of these mice decreases blood vessel establishment suggesting that these microRNAs could be used as therapeutic antiangiogenic agents. Taken together, the results presented in this thesis show that miR-21 and miR-125b regulate angiogenesis in vitro and in vivo. [less ▲]

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See detailIntermédiaires et dynamique des réseaux fluides. Du mode d'existence de la norme ISO 14001 en Région wallonne
Semal, Nathalie ULg

Doctoral thesis (2011)

How does a standard "make a living"? How does a written list of requirements acquire some reality? How can a particular agreement take effect in numerous worldwide distant sites?

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See detailRole de l'ADN endogène et d'Interferon Response Factor-3 dans l'induction des réponses immunitaires médiées par les lymphocytes T auxiliaires de type 2.
Marichal, Thomas ULg

Doctoral thesis (2011)

Adaptative type 2 helper T cell (Th2) responses represent an important component of adaptative immunity and are implicated in various (patho)physiological processes such as allergic diseases, host defense ... [more ▼]

Adaptative type 2 helper T cell (Th2) responses represent an important component of adaptative immunity and are implicated in various (patho)physiological processes such as allergic diseases, host defense against helminths and artificially adjuvanted vaccination. Induction of adaptative T responses occurs with the help of innate immune cells, especially dendritic cells (DCs). These DCs make the link between innate and adaptative immunity by taking up antigens in peripheral tissues, migrating to lymphoïd organs and presenting antigens to T lymphocytes. Direct or indirect activation of these cells depends on the interaction between exogenous or endogenous danger signals and conserved innate immune receptors, mainly represented by Pattern Recognition Receptors (PRRs). Despite the importance of Th2 responses, the innate immune mechanisms leading to their activation remain partially unknown. For this reason, we have been interested in immune mechanisms underlying the induction of Th2 responses in two major Th2-dependent immunological processes : airway allergy and vaccination with aluminium hydroxides (alum). Airway allergy, of which the most severe manifestation is allergic ashma, is a constantly increasing disease in developped countries. It appears clearly that the stimulation of PRRs by allergens or immunostimulatory molecules plays a key role in the pathophysiology of airway allergy. In addition, PRRs transduce the signal though a limited number of signaling pathways and the role of Interferon Response Factor (IRF)-3 and IRF-7, two important transcription factors downstream of various PRRs, in the pathogenesis of allergic asthma, remains unknown. Therefore, we have investigated their potentiel implication in this disease. We have discovered that IRF-3, but not IRF-7, plays an essential role in allergic airway sensitization against house dust mite antigens, the main allergen source in humans. We have further demonstrated that IRF-3 was intrinsically required in lung DCs for their proallergic function. The IRF-3-dependent effects were independent of type I interferons, the main target genes of IRF-3. Alum is the most widely used artificial adjuvant in human and animal vaccination. Yet, little is known about its mechanism of action, in particular regarding the nature of signals and signaling pathways promoting Th2 responses. We have postulated that alum, like any other efficient adjuvant, must be expected to stimulate innate immunity. On one hand, alum does not contain any molecular pattern that is recognized by PRRs and, on the other hand, alum is known to be cytotoxic. Therefore, we hypothetised that alum-induced endogenous danger signals could play a role in its adjuvant activity. Here, we report that alum induces cell death and subsequent DNA release. This DNA acts as a endogenous immunostimulatory signal relaying alum adjuvant activity on adaptative responses. Furthermore, we propose that host DNA differentially regulates IgG1 and IgE production following alum immunization. Indeed, an IRF-3-dependent DNA signaling pathway plays a role in the activation of inflammatory DCs, the subsequent induction of Th2 response and IgE isotype switching, whereas DNA also induces IgG1 production through IRF-3- independent mechanisms. The finding that host cell endogenous DNA is a damageassociated molecular pattern relaying alum adjuvant activity may thus help in the comprehension of the mechanisms of action of current vaccines and in the design of novel adjuvants. In conclusion, this work has identified a previously unappreciated role for IRF-3, a transcription factor downstream of various PRRs primarily implicated in antiviral responses, in two Th2-dependent immunological processes: allergic asthma and alum-based vaccination. In these models, we have shown that IRF-3 was intrinsically required in professional antigen presenting cells, namely DCs, in order to activate them, a precondition for the priming of adaptative Th2 responses. In addition, we also discovered that host DNA released upon alum treatment acts as an endogenous danger signal mediating the adjuvant activity of alum. [less ▲]

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See detailSemi-solid constitutive modeling for the numerical simulation of thixoforming processes.
Koeune, Roxane ULg

Doctoral thesis (2011)

Semi-solid thixoforming processes rely on a material microstructure made of globular solid grains more or less connected to each other, thus developing a solid skeleton deforming into a liquid phase ... [more ▼]

Semi-solid thixoforming processes rely on a material microstructure made of globular solid grains more or less connected to each other, thus developing a solid skeleton deforming into a liquid phase. During processing, the material structure changes with the processing history due to the agglomeration of the particles and the breaking of the grains bonds. This particular evolutive microstructure makes semi-solid materials behave as solids at rest and as liquids during shearing, which causes a decrease of the viscosity and of the resistance to deformation while shearing. Thixoforming of aluminum and magnesium alloys is state of the art and a growing number of serial production lines are in operation all over the world. But there are only few applications of semi-solid processing of higher melting point alloys such as steel. This can partly be attributed to the high forming temperature combined with the intense high temperature corrosion that requires new technical solutions. However the semi-solid forming of steels reveals high potential to reduce material as well as energy consumption compared to conventional process technologies, such as casting and forging. Simulation techniques exhibit a great potential to acquire a good understanding of the semi-solid material process. Therefore, this work deals with the development of an appropriate constitutive model for semi-solid thixoforming of steel. The constitutive law should be able to simulate the complex rheology of semi-solid materials, under both steady-state and transient conditions. For example, the peak of viscosity at start of a fast loading should be reproduced. The use of a finite yield stress is appropriate because a vertical billet does not collapse under its own weight unless the liquid fraction is too high. Furthermore, this choice along with a non-rigid solid formalism allows predicting the residual stresses after cooling down to room temperature. Several one-phase material modeling have been proposed and are compared. Thermo-mechanical modeling using a thermo-elasto-viscoplastic constitutive law has been developed. The basic idea is to extend the classical isotropic hardening and viscosity laws to the non solid state by considering two non-dimensional internal parameters. The first internal parameter is the liquid fraction and depends on the temperature only. The second one is a structural parameter that characterizes the degree of structural build up in the microstructure. Those internal parameters can depend on each other. The internal parameters act on the the viscosity law and on the yield surface evolution law. Different formulations of viscosity and hardening laws have been proposed and are compared to each other. In all cases, the semi-solid state is treated as a particular case, and the constitutive modeling remains valid over the whole range of temperature, starting from room temperature to above the liquidus. These models are tested and illustrated by mean of several representative numerical applications. [less ▲]

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See detail"Intentionnalité et inconscient. Réflexions sur le fonctionnement de la vie psychique à partir du premier Husserl et de Freud"
Gyemant, Maria ULg

Doctoral thesis (2011)

This work tries the limits of Husserl’s concept of intentionality as it is conceived in the Logical Investigations. Once these limits exposed, we claim that Husserl’s theory of intentionality be completed ... [more ▼]

This work tries the limits of Husserl’s concept of intentionality as it is conceived in the Logical Investigations. Once these limits exposed, we claim that Husserl’s theory of intentionality be completed with a theory of the unconscious of Freudian inspiration. Thus, on the conceptual basis of Husserl and Freud’s work we elaborate an exhaustive map of the human mind, that shows not only the consciousness, but also the other mental phenomena. Our first section shows that Husserl’s concept of intentionality is established in opposition to Brentano’s intentionality. We also analyse the problem it is meant to solve, namely how exactly the mind connects with its objects. We show that this way of understanding intentionality cannot explain the dynamical aspect of intentional acts. Our second section is thus dedicated to this issue. A group of texts written by Husserl around 1913-1914 on the concept of tendency show clearly that Husserl never stopped in fact questioning the dynamical character of intentionality although he couldn’t explain it without thinking it as a form of intentionality. This solution leads nevertheless to an infinite regress. We have chosen thus in our third section to try a new approach of the dynamical aspect by using Freud’s approach to the Unconscious. The Freudian Unconscious has thus been articulated to Husserl’s theory of intentionality and at the same time the dynamical aspect of the latter has found an appropriate conceptual expression. [less ▲]

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See detailOn the sets of real vectors recognized by finite automata in multiple bases
Brusten, Julien ULg

Doctoral thesis (2011)

This thesis studies the properties of finite automata recognizing sets of real vectors encoded in positional notation using an integer base. We consider both general infinite-word automata, and the ... [more ▼]

This thesis studies the properties of finite automata recognizing sets of real vectors encoded in positional notation using an integer base. We consider both general infinite-word automata, and the restricted class of weak deterministic automata, used, in particular, as symbolic data structures for representing the sets of vectors definable in the first order additive theory of real and integer numbers. In previous work, it has been established that all sets definable in the additive theory of reals and integers can be handled by weak deterministic automata regardless of the chosen numeration base. In this thesis, we address the reciprocal property, proving that the sets of vectors that are simultaneously recognizable in all bases, by either weak deterministic or Muller automata, are those definable in the additive theory of reals and integers. Precisely, for weak deterministic automata, we establish that the sets of real vectors simultaneously recognizable in two multiplicatively independent bases are necessarily definable in the additive theory of reals and integers. For general automata, we show that the multiplicative independence is not sufficient, and we prove that, in this context, the sets of real vectors that are recognizable in two bases that do not share the same set of prime factors are exactly those definable in the additive theory of reals and integers. Those results lead to a precise characterization of the sets of real vectors that are recognizable in multiple bases, and provide a theoretical justification to the use of weak automata as symbolic representations of sets. As additional contribution, we also obtain valuable insight into the internal structure of automata recognizing sets of vectors definable in the additive theory of reals and integers. [less ▲]

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See detailLes papyrus scolaires grecs et latins chrétiens
Carlig, Nathan ULg

Master's dissertation (2011)

Detailed reference viewed: 15 (2 ULg)
See detailNutrient fluxes and soil microbial processes
Bazgir, Masoud ULg

Doctoral thesis (2011)

Because of previous intense forest use and over exploitation in the past centuries, the plantation of coniferous stands, especially Norway spruce (Picea abies L. KARST.) with high production potentials ... [more ▼]

Because of previous intense forest use and over exploitation in the past centuries, the plantation of coniferous stands, especially Norway spruce (Picea abies L. KARST.) with high production potentials has been a common European afforestation strategy. However, the characteristics of Norway spruce such as susceptibility to windfall, forest dieback, drought, as well as soil acidification have caused negative ecological impacts in many sites. Conversion of conifers into deciduous or mixed stands has been suggested by some foresters, in order to improve the stability, ecology and biodiversity of forest ecosystems. Such changes in forest management require specific information on the impact of tree species on nutrient cycling, soil properties and microbial activities. In this study, six broadleaved species were growing at the same site with similar condition in terms of soil type, land use history and climate. Thus, the potential effects on biogeochemical cycling could be attributed to tree species. In this thesis, I focused on the effect of broadleaved species (conversion scenario) contrasting in terms of ecological characteristics (pioneer species versus main forestry species) and physiological characteristics (N2-fixing tree species (alder) versus non N2-fixing species) and Norway spruce (no conversion scenario) on (a) soil chemical properties (b) soil microbial activities and microbial biomass (c) nutrient input fluxes from throughfall and litterfall (d) foliar nutrient status. This investigation was carried out in south-eastern Belgium at a site converted in 1998 to a mixed deciduous stand, after two spruce generations. Plantations of common alder (Alnus glutinosa (L.) GAERTN.), european beech (Fagus sylvatica L.), pedunculate oak (Quercus robur L.), silver birch (Betula pendula ROTH.), goat willow (Salix caprea L.) and rowan (Sorbus aucuparia L.) were located in 4 fenced plots within a 81 ha catchment. Soil chemical properties (soil organic matter, pH, cation exchange capacity, base saturation, exchangeable cations), soil microbial activities (net N mineralization, potential nitrification, basal respiration) and microbial biomass (microbial biomass C and N) were measured under broadleaves and spruce. Soil chemistry of this highly acid soil was improved, 11 years after conversion, through an increase in base saturation and the exchangeable Mg2+ pool under rowan, as well as an increase in the exchangeable Ca2+ pool under alder, oak and rowan. Exchangeable acidity due to H+ in the forest floor also decreased under broadleaves. Nitrification was increased under the N2 fixing alder and decreased under young spruce. The C:N ratio of cold water-extractable soil organic matter fractions revealed to be a good indicator of potential nitrification rates within this site and across species, with a threshold of a C:N ratio of 10 above which soils did not nitrify. Throughfall and litterfall under the tree species were investigated by installing 63 throughfall collectors and 63 litter traps within 3 fenced plots (broadleaves) and across the catchment (young spruce). We measured the quantity of litterfall (foliar, twigs, reproductive parts and total), the quality of foliar litterfall (macro and micro-elements and C/N ratio) and calculated the potential nutrient return to the forest floor though foliar litterfall. For throughfall, we analyzed macro and micro-element concentrations and throughfall fluxes. Foliar nutrient status was determined by chemical analyses of fresh leaves and spruce needles of 3 age classes. The throughfall deposition of Ca2+, Mg2 and K+ was significantly higher under rowan and birch. NO3--N throughfall fluxes were significantly higher under young spruce compared to broadleaves. We observed the lowest total litterfall quantity produced by oak, while the highest litterfall quantity observed under rowan. Foliar litterfall of rowan showed significantly higher potential nutrient fluxes of Ca, Mg and K compared to other species, which corresponds to fresh foliage concentrations. The foliar litterfall was a main source of Ca, while for K throughfall was the main source of nutrient return to the forest floor in the study area. In spruce needles, Ca and Mg concentrations were at deficiency level and K concentrations at critical level, according to threshold values. Our results demonstrated that the plantation of pioneer species, especially rowan, may enhance the base cations in the forest floor on nutrient poor, acid soils through higher input in litterfall and throughfall. [less ▲]

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See detailApplication du Laser Cladding au rechargement et à la fabrication de pièces
Hardenne, Thibaut ULg

Master's dissertation (2011)

Ce travail commence par présenter les techniques de fabrication par addition de matière dont le procédé Laser Cladding (dépôt de poudre métallique par laser). Puis, ce procédé est comparé aux techniques ... [more ▼]

Ce travail commence par présenter les techniques de fabrication par addition de matière dont le procédé Laser Cladding (dépôt de poudre métallique par laser). Puis, ce procédé est comparé aux techniques de rechargement conventionnelles sur base de résultats présentés dans la littérature. Deux types d'essais expérimentaux ont ensuite été étudiés. Premièrement, des blocs ont été réalisés en acier inoxydable 316L sur un substrat en acier S235 à l'aide d'un laser bre de 300W. Les paramètres ont été optimisés a n d'obtenir une bonne fusion et un bon recouvrement entre cordons. L'optimisation se base sur des analyses d'échantillons polismiroir. La porosité a été estimée par seuillage d'image, mais les blocs étaient globalement fort denses. La microstructure a révélé des grains s'étendant sur plusieurs couches et compos és de cellules. Des essais de microdureté et des analyses EDX ont montré qu'il existait une zone de dilution plus dure à la frontière substrat/revêtement. La taille des cellules est plus grande au sommet des blocs qu'à la base, si bien que la dureté diminue en s'éloignant de la liaison. La stratégie de traçage in uence les propriétés mécaniques obtenues lors de tests de traction. Deuxièmement, des parois en titane Ti-6Al-4V ont été fabriquées sur un substrat de même nature, dans une tente gon ée à l'argon pour se protéger de l'oxydation. Cependant la surface colorée des parois et les essais de microdureté ont mis en évidence une oxydation des premiers cordons. Les parois ne contenaient pas de porosité et la microstructure était composée de grains colonaires s'étendant verticalement. Ces grains avaient une structure aciculaire de type Widmänstatten. Le travail se termine par une recherche bibliographique des possibilités de préchau age du substrat lors de la fabrication par Laser Cladding. [less ▲]

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See detailUn nouveau regard sur les reliefs en marbre noir de Theux sculptés au XVIe siècle à Liège et ses environs, 3 vol.
Warnauts, Samuelle ULg

Master's dissertation (2011)

Analyse et réévaluation critique suivies d’un catalogue complet d’œuvres réalisées en marbre noir dit de Theux.

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See detailImprovement of randomized ensembles of trees for supervised learning in very high dimension
Joly, Arnaud ULg

Master's dissertation (2011)

Tree-based ensemble methods, such as random forests and extremely randomized trees, are methods of choice for handling high dimensional problems. One important drawback of these methods however is the ... [more ▼]

Tree-based ensemble methods, such as random forests and extremely randomized trees, are methods of choice for handling high dimensional problems. One important drawback of these methods however is the complexity of the models (i.e. the large number and size of trees) they produce to achieve good performances. In this work, several research directions are identified to address this problem. Among those, we have developed the following one. From a tree ensemble, one can extract a set of binary features, each one associated to a leaf or a node of a tree and being true for a given object only if it reaches the corresponding leaf or node when propagated in this tree. Given this representation, the prediction of an ensemble can be simply retrieved by linearly combining these characteristic features with appropriate weights. We apply a linear feature selection method, namely the monotone LASSO, on these features, in order to simplify the tree ensemble. A subtree will then be pruned as soon as the characteristic features corresponding to its constituting nodes are not selected in the linear model. Empirical experiments show that the combination of the monotone LASSO with features extracted from tree ensembles leads at the same time to a drastic reduction of the number of features and can improve the accuracy with respect to unpruned ensembles of trees. [less ▲]

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See detailMéthodes d'identification des paramètres dans un modèle du système cardiovasculaire
Pironet, Antoine ULg

Master's dissertation (2011)

Les dysfonctions du système cardiovasculaire sont une origine majeure des admissions dans les unités de soins intensifs. Dans ces unités, les patients sont très instables et les cliniciens disposent d’un ... [more ▼]

Les dysfonctions du système cardiovasculaire sont une origine majeure des admissions dans les unités de soins intensifs. Dans ces unités, les patients sont très instables et les cliniciens disposent d’un nombre limité de mesures pour prendre rapidement les bonnes décisions. L’utilisation de modèles patient-spécifiques pour guider les clini- ciens offre alors des perspectives réelles. Un modèle simple à six compartiments du système cardiovasculaire a été développé par Smith et al. et une méthode d’identification des paramètres de ce modèle a été développée par Revie et al. Ce modèle a été étendu en y ajoutant deux compartiments représentant les oreillettes, dont le comportement est décrit par un modèle inspiré de travaux existants. Une méthode d’identification similaire à celle utilisée par Revie et al. a été développée pour les nouveaux paramètres. Pour ne pas devoir recourir à la pression auriculaire, difficile à mesurer expérimentalement, une méthode permettant de déduire la pression auriculaire à partir de la pression ventriculaire a également été introduite. L’application du modèle étendu et de la méthode d’identification correspondante à des données expérimentales montre que l’introduction des oreillettes dans le modèle ne cause pas de trop grandes erreurs et que la méthode d’estimation de la pression auriculaire est correcte. En conclusion, la valeur ajoutée de la méthode développée dans ce travail est grande, puisqu’elle permet d’obtenir des informations supplémentaires sans introduire de grandes erreurs et sans imposer le besoin de recourir à de nouvelles mesures. [less ▲]

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See detailActivité et modulation de la NADPH oxydase des neutrophiles équins: tests in vitro sur cellules entières et mise au point du dosage en "cell-free system"
Derochette, Sandrine ULg

Master's dissertation (2011)

Chez le cheval, la réponse inflammatoire causée par certaines pathologies (obstruction intestinale, fourbure,…) implique une stimulation excessive des polymorphonucléaires neutrophiles (PMNs) libérant de ... [more ▼]

Chez le cheval, la réponse inflammatoire causée par certaines pathologies (obstruction intestinale, fourbure,…) implique une stimulation excessive des polymorphonucléaires neutrophiles (PMNs) libérant de grandes quantités d’espèces activées de l’azote et de l’oxygène (RNOS). La première enzyme impliquée dans la formation de ces espèces activées est la NADPH oxydase, produisant l’anion superoxyde (O2.-) d’où dérivera la formation de diverses RNOS. Actuellement, la NADPH oxydase est considérée comme une cible privilégiée pour la modulation de l’inflammation excessive. Le but de ce travail a été d’étudier l’effet de molécules modulant la réponse inflammatoire (la curcumine, la quercétine et l’acépromazine : ACP) ou l’activité de la NADPH oxydase (le diphénylène iodonium : DPI) sur la production de RNOS par les PMNs stimulés. L’étude a été menée sur des PMNs équins isolés où la production de RNOS a été mise en évidence par trois techniques différentes : la chimiluminescence assistée par la lucigénine et la réduction du ferricytochrome C, ciblant essentiellement la production d’O2.- ; et une technique de fluorescence utilisant la 2’,7’-dichlorofluorescine-diacétate (DCFH-DA), ciblant la production intra et extracellulaire de RNOS. L’effet de ces molécules a pu être testé de façon plus spécifique sur la NADPH oxydase par une mesure en « cell-free system » que nous avons mise au point et consistant en la reconstitution in vitro de la NADPH oxydase. Nous avons constaté que les molécules polyphénoliques testées (quercétine et curcumine) agissaient surtout comme des antioxydants stoechiométriques en neutralisant les RNOS intracellulaires et extracellulaires sans pour autant être des inhibiteurs de la NADPH oxydase. Nous avons également démontré que certaines molécules (l’ACP et le DPI) utilisées à forte concentration pouvaient amplifier la réponse oxydante des PMNs. Enfin, grâce à la technique du « cell free system » nous avons démontré, pour la première fois, l’effet anti-catalytique du DPI sur la NADPH oxydase équine. La complémentarité de ces techniques permettra de faire la distinction entre un effet antioxydant, pro-oxydant ou anti-catalytique d’une molécule biologique pouvant moduler la réponse inflammatoire. Enfin, ce travail présente les premiers résultats de l’isolement des sous-unités membranaires de la NADPH oxydase équine. Les résultats sont encourageants et la purification à plus long terme du complexe enzymatique entier avec la production d’anticorps spécifiques devrait permettre la mise au point d’un dosage original de la NADPH oxydase consistant en l’immuno-capture de l’enzyme active afin de cibler l’effet de substances biologiques sur son assemblage et son activité spécifique. [less ▲]

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See detailEconomic and environmental impacts of several retrofit options for residential buildings
Gendebien, Samuel ULg

Master's dissertation (2011)

Nowadays, important efforts are deployed to reduce our actual residential building consumption which represents about 40% (25% for the residential sector and 15% for the non-residential sector) of the ... [more ▼]

Nowadays, important efforts are deployed to reduce our actual residential building consumption which represents about 40% (25% for the residential sector and 15% for the non-residential sector) of the total energy consumption in Europe. The aim of this paper is to evaluate the environmental and economical impact of several retrofit options for residential buildings. Our study focuses on the Walloon Region of Belgium. A “bottom-up” methodology is applied: this methodology focuses first on a micro-analysis. Results from this micro-analysis are then used and extended to a macro-analysis. The presented methodology does not permit to determine with precision the global consumption of residential buildings in the Walloon Region. However, the latter methodology allows pointing out some economical and environmental trends related to the different investigated retrofit options. The first part of this end-of-study work offers an overview of the Walloon building stock by presenting statistic data on the Walloon residential houses. From these latter statistic data, it is possible to divide the Walloon building stock by means of arborescence. Each type of building is characterized by constructive data (mean area, Uwall, Uwindow…) and by heating production system efficiency. Thanks to these data, it is possible to determine the gas and electrical annual consumption for each type of residential building by means of a computer program that simulates residential building. The latter computer program is also used to determine the annual energy consumption of envelope retrofitted houses. Retrofit options related to heat and/or cool production are also investigated. A macro-point of view study is carried out in order to determine the potential of energy saving of each investigated options. An environmental comparison between the several envisaged retrofit options is realized in terms of CO2 emission, final and primary annual energy consumption for each type of building. An economical study is carried out in order to determine the profitability of each investigated options for citizens. The work also proposes a reflection about the actual incentive policies. [less ▲]

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See detailTheoretical and Experimental Analysis of Liquid Flooded Compression in Scroll Compressors
Bell, Ian ULg

Doctoral thesis (2011)

Adding liquid to the working fluid in scroll compressors can allow for a working process that approaches isothermal compression. When liquid flooding and regeneration is applied to refrigeration and heat ... [more ▼]

Adding liquid to the working fluid in scroll compressors can allow for a working process that approaches isothermal compression. When liquid flooding and regeneration is applied to refrigeration and heat pump systems, simple cycle modeling predicts that for systems that operate at very large temperature lifts, the increase in system coefficient of performance can be greater than 50%. In order to better understand the liquid-flooded working process, a detailed scroll compressor model has been developed which comprises a geometric model and an overall compressor model. The geometric model includes numerically validated analytic solutions for all geometric parameters, including force terms, for constant wall thickness scroll wraps that can have multiple pairs of compression chambers. The overall model includes a frictionally-corrected isentropic nozzle leakage model, adaptive Runge-Kutta solver for the system of differential equations, and numerically efficient thermodynamic and transport property routines. The compressor model has been validated against testing conducted on the Liquid-Flooded Ericsson Cycle for oil mass fractions as high as 92% oil by mass with error in predictions of shaft power and mass flow less than 3%. Optimization of the compressor performance with flooding for several applications is carried out, and with optimization, overall isentropic efficiencies over 75% are predicted for configurations with large amounts of oil flooding. Further testing on a refrigerant R410A vapor injected compressor with oil injection has shown that the performance with oil injection improves monotonically with the oil injection rate as long as the oil is cooled prior to injection. [less ▲]

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See detailNational Mythology and Colonial Trauma in Alex Miller’s Journey to the Stone Country
Joubail, Houda ULg

Master's dissertation (2011)

In 1991 the Australian government instigated a process of reconciliation between indigenous and non-indigenous people. This process aimed at laying the foundations of a postcolonial nation through the ... [more ▼]

In 1991 the Australian government instigated a process of reconciliation between indigenous and non-indigenous people. This process aimed at laying the foundations of a postcolonial nation through the establishment of the truth about the past, the acknowledgment of the injustices inflicted on the natives, and the development of appropriate forms of justice. Hidden facts about dispossession and genocide were divulged thanks to various inquiries carried out throughout the country. Such hideous facts plunged settler Australians into angst and guilt and prompted many contemporary white novelists to tackle the hitherto taboo issue of colonialism and its legacies in their works. At first glance, this literary endeavour to deal with the darkest chapter in the Australian history appears as a genuine determination to confront the trauma of the colonial past. Nevertheless, a closer look at some contemporary Australian novels reveals an altogether different intention. My dissertation seeks to explore the fictional representations of colonialism and Aboriginal suffering in one of these novels, namely, Alex Miller’s Journey to the Stone Country (2002), in order to emphasise how, through the use of subtle representational and discursive strategies, the author contrives to lessen the impact of the colonial violence. Annabelle Beck, a descendant of British settlers, and Bo Rennie, a former Aboriginal ringer, set out on a journey from Burranbah in Central Queensland to the sacred ground of the Jangga people. As the journey unfolds, a disturbing past of injustice and loss emerges. The two main protagonists are brought to discover their common history as members of neighbouring families. The exploration of their past culminates in the revelation of a massacre in which Bo’s ancestors were savagely killed by Annabelle’s grandfather and his friends. Admittedly, the author tackles the controversial issues of inter-racial relationships, dispossession, and the legacies of colonial violence, yet his approach is far from being postcolonial. The first part of the dissertation will, indeed, attempt to examine how he makes use of the representational strategies to portray the Aboriginal characters as uneducated, untrustworthy, and racist. Furthermore, this part will emphasise that Miller tends to dismantle colonial myths only to construct neo-colonial ones, particularly, the equal importance of European and Aboriginal heritages. This assumption of egalitarianism is, in fact, not as fair as it seems at first sight given the long history of injustices to which Aborigines were subjected. The second part of the dissertation is dedicated to the analysis of the author’s response to the colonial trauma. A close reading of the novel in the lights of trauma theories reveals that the author resists the full understanding and acknowledgement of the truth about the past. He, indeed, undermines his avowed intention of exposing the atrocities inflicted on Aboriginal people through a series of discursive strategies. The dissertation will mainly draw on Dominick LaCapra’s writings about trauma to suggest that Miller is caught within the process of what LaCapra refers to as “acting out”, that is to say the tendency to repress the traumatic past to avoid any critical confrontation. Therefore, though he apparently engages in the venture of exploring the colonial past, Miller advocates the law of silence, a law which is hardly compatible with the requirements of a true reconciliation. [less ▲]

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See detailEtude tribologique des matériaux de cage de roulement à billes en ambiance cryogénique
Servais, Christophe ULg

Master's dissertation (2011)

Le lien étroit entre le matériau constituant entièrement ou partiellement la cage d’un roulement à billes fonctionnant en ambiance cryogénique et la lubrification solide, employée dans ce domaine ... [more ▼]

Le lien étroit entre le matériau constituant entièrement ou partiellement la cage d’un roulement à billes fonctionnant en ambiance cryogénique et la lubrification solide, employée dans ce domaine particulier, a été mis en avant. Une comparaison des forces présentes aux contacts des billes et des bagues du roulement a pu être effectuée dans deux cas bien précis : en présence et en l’absence d’un lubrifiant. Ainsi, ces calculs ont montré une nette différence entre les deux configurations précitées, à l’avantage des pistes lubrifiées. Plus encore, la corrélation entre une défaillance au niveau de la lubrification et l’apparition d’un mouvement erratique du séparateur a été observée et quantifiée. De fait, une modélisation bidimensionnelle de la cage a été développée dans ce travail et le comportement de cette dernière a en effet révélé que plusieurs paramètres tribologiques interviennent de près ou de loin dans l’entrée en phase instable de ladite cage. [less ▲]

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See detailEpigenetic Therapy of Lung Cancers: Anti-tumoral effect of valproate on small cell lung cancer
Hubaux, Roland ULg

Doctoral thesis (2011)

Lung cancer is the leading cause of cancer-related death worldwide. Among lung carcinomas, the outcome of small cell lung carcinoma (SCLC) patients is the poorest of any histological subtype with five ... [more ▼]

Lung cancer is the leading cause of cancer-related death worldwide. Among lung carcinomas, the outcome of small cell lung carcinoma (SCLC) patients is the poorest of any histological subtype with five-year survival rate of less than 20 and 5 % for limited and extensive stage respectively. Based on increasing evidence that inhibitors of histones deacetylases (HDAC) have anticancer properties, the goal of this study was to evaluate the ability of valproate (VPA) to improve efficacy of chemotherapeutic regimen in SCLC. We show that VPA directly induces apoptosis of SCLC cell lines at concentrations relevant for clinical uses. Furthermore, VPA synergizes with two chemotherapeutic regimen used in first (cisplatin + etoposide) and second line (cyclophosphamid + vindesine + doxorubicin) treatments. Both mitochondrial and death receptor pathways are involved in VPA-induced apoptosis. Although VPA promotes production of reactive oxygen species, free radical scavenger N-acetylcystein is not sufficient to inhibit apoptosis. As expected, VPA triggers hyperacetylation of histone H3 and increases expression of p21. VPA reduces levels of BclxL, induces cleavage of Bid, translocation of Bax to mitochondria, release of cytochrome c into cytosol and phosphorylation of Erk and H2AX. Transcriptomic analyses by microarrays and quantitative RT-PCR have underscored a series of genes candidates potentially implicated into sensitivity of SCLC to VPA. Among these, the Fzd7 receptor of the WNT pathway is essential for VPA proapoptotic activity. Efficiency of VPA combined to first and second line chemotherapeutic agents is supported by preclinical models of SCLC cells engrafted into SCID mice. The second line combination is presently tested in a clinical trial with patients presenting with refractory or relapsing small cell lung cancer (protocol 01081 at http://www.elcwp.org). [less ▲]

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See detailOptimally Locating Facilities with Variable Characteristics
Kucukaydin, Hande ULg

Doctoral thesis (2011)

Facility location problems aim at optimally locating facilities like plants, warehouses, convenience stores, shopping malls etc. They can have different objectives such as maximizing the profit gained ... [more ▼]

Facility location problems aim at optimally locating facilities like plants, warehouses, convenience stores, shopping malls etc. They can have different objectives such as maximizing the profit gained from the customers or minimizing the costs of locating facilities and serving the customers. In this thesis, we mainly focus on competitive facility location problems which constitute a special family. In a competitive facility location problem, a firm or franchise is concerned with installing new facilities to serve customers in a market where existing facilities with known locations and attractiveness levels compete for increasing their market share and profit. We can classify these problems into two groups: those with non-reactive competition and those with reactive competition. Three different types of competitive facility location models are proposed in order to determine the locations and attractiveness levels of the new facilities to maximize the profit in this thesis. The first one belongs to the former class, where the last two models fall into the latter one. We formulate the first one as a mixed-integer nonlinear programming problem and propose three methods for its solution: a Lagrangean heuristic, a branch-and-bound method with Lagrangean relaxation, and a branch-and-bound method with nonlinear programming relaxation. The computational results obtained on a set of problem instances show that the branch-and-bound method using nonlinear programming relaxation is the most efficient and accurate solution method in order to solve the proposed problem. We consider next an extension of this model by relaxing the assumption that the competitor in the market does not react to the opening of new facilities. In other words, the competitor can react by adjusting the attractiveness levels of its existing facilities with the objective of maximizing its own profit. To this end, a bilevel mixed-integer nonlinear programming model is formulated. We transform this bilevel model into an equivalent one-level mixed-integer nonlinear program and solve it by a global optimization method. For this problem, we also consider a scenario in which the new entrant firm ignores the reaction of the competitor. The experimental results indicate that anticipating the competitor's reaction by including this into his optimization problem increases the profit of the new entrant firm, whereas the competitor's profit is decreased. The last competitive facility location model relaxes the limitation about the competitor's reaction: now the competitor can also open new facilities, close existing ones and/or adjust their attractiveness. This also formulates a bilevel mixed-integer nonlinear programming problem which we try to solve by combining tabu search with global optimization algorithms. We develop three different tabu search methods and the computational results on a set of problem instances for comparing the performance of the solution methods show that the third tabu search method is the most accurate one, while the second tabu search method is the most efficient solution procedure. Finally, we consider a different facility location problem which takes the customer preferences into account. The facilities are not necessarily identical and customers visit different types of facilities according to some given probability distribution and the maximum distance which they are willing to travel. We formulate a binary linear programming problem and solve it by three procedures that include a Lagrangean heuristic whose solution is improved further using a local search method. Based on the experimental results carried out on a set of problem instances the third solution method is the most efficient one. However, a statistical analysis on the quality of the solutions states that there is no significant difference between the three solution procedures. [less ▲]

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