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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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See detailEssays in Portfolio Performance Analysis
Cogneau, Philippe ULg

Doctoral thesis (2013)

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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See detailThe role of galectins in the vasculature
Heusschen, Roy ULg

Doctoral thesis (2013)

Detailed reference viewed: 8 (0 ULg)
See detailLes représentations linguistiques des étudiants Erasmus et la vision plurilingue européenne: normes, discours, apprentissages
Meunier, Deborah ULg

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2013)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

Doctoral thesis (2012)

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

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

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

Doctoral thesis (2012)

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

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

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See detailEtude des mécanismes responsables du comportement agrégatif d’Harmonia axyridis (Pallas) (Coleoptera : Coccinellidae)
Durieux, Delphine ULg

Doctoral thesis (2012)

The negative impacts linked to the introductions of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), progressively increasing in Europe and in North America, it is urgent to find a way to ... [more ▼]

The negative impacts linked to the introductions of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), progressively increasing in Europe and in North America, it is urgent to find a way to manage its populations. The social interactions involved in its aggregative behavior remain misunderstood although a better understanding of the semiochemicals the ladybeetles use during this phenomenon could lead to the development of new control methods. Therefore, the main objective of this thesis was to improve the understanding of the mechanisms set up by H. axyridis during its aggregative stage. Firstly, we have demonstrated the use of two different area markings by this species during its overwintering. The first one, laid by the ladybeetles while walking, lead conspecifics towards aggregation sites whereas the second one, deposited inside these sites, ensures the cohesion of the cluster. These markings are made up of saturated, mono- and diunsaturated hydrocarbons. Among these chemicals, it seems that the unsaturated hydrocarbons, and in particular the ones containing two double bonds, present a greater biological activity. However, the response of H. axyridis towards these chemicals depends on the insect physiological state. In the second instance, we have showed for the first time that H. axyridis presents a permanent aggregative behavior. The hydrocarbons laid by the ladybeetles during their displacements do not play any role in this behavior during summer conditions. On the other hand, conspecific elytral compounds and, in a lesser extent, physical contact, are well involved. Moreover, all our experiments have pointed out that visual elements play a major role in this social behavior and so, have also to be taken into account in the design of traps to control the populations of this invasive species. [less ▲]

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See detailCoastal pollution of the Mediterranean and extension of its biomonitoring to trace elements of emerging concern
Richir, Jonathan ULg

Doctoral thesis (2012)

The Mediterranean Sea, a semi-enclosed sea with densely populated coasts, is submitted to numerous anthropogenic pressures: among them, the chemical pollution by traces elements. These pollutants, coming ... [more ▼]

The Mediterranean Sea, a semi-enclosed sea with densely populated coasts, is submitted to numerous anthropogenic pressures: among them, the chemical pollution by traces elements. These pollutants, coming from our continental activities, are transported through rivers or by air and accumulate in seas and oceans where they mainly affect coastal areas. During the 70ies, scientists suggested to use organisms, in particular mussels of the genus Mytilus, in order to evaluate the status of chemical contamination of coastal ecosystems. Biomonitoring was born. Since, many monitoring studies were published using various animal and vegetal species. Two of the most studied bioindicators species in the Mediterranean are the marine magnoliophyte Posidonia oceanica and the Mediterranean mussel Mytilus galloprovincialis. Monitoring studies with these two species have mainly focussed on contaminations by Cr, Ni, Cu, Zn, Cd, Pb (Mytilus galloprovincialis and Posidonia oceanica), Fe (Posidonia oceanica), As, V and Ag (Mytilus galloprovincialis). However, other trace elements like Be, Al, Mn, Co, Se, Mo, Sn, Sb and Bi have been subject to nearly no ecotoxicological survey. Furthermore the worldwide evolution of our technologies and of our lifestyle increases the extraction and production of trace elements (notably to answer needs of developing countries). The biomonitoring of the pollution by trace elements is henceforth a topical subject. The overall objective of this work was therefore to evaluate the potential use of Mytilus galloprovincialis and Posidonia oceanica as bioindicators to monitor the Mediterranean coastal pollution by Be, Al, Mn, Co, Se, Mo, Sn, Sb, Bi, Fe, As, V, and Ag. These trace elements, mostly little studied, can be categorized as elements of “environmental emerging concern”. A time-integrated efficient monitoring of trace elements requires the continuous survey of their environmental levels; we therefore also measured levels of trace elements classically monitored with these two species. Mytilus galloprovincialis and Posidonia oceanica complement each other in monitoring surveys. Both species accumulate pollutants dissolved in the water column. Posidonia oceanica, rooted in the seafloor, accumulates moreover pollutants stored in sediments in the long term. Mytilus galloprovincialis, as a filter feeder, further accumulate particulate pollutants suspended in the water column. The combined use of both bioindicators therefore provides a global view of the health status of the coastal environment (water, sediments, suspended matter). Our first goal was to measure, at the scale of the French Mediterranean littoral, the spatial variability of trace element contents in Posidonia oceanica, and to determine if trace elements of environmental emerging concern threaten the chemical integrity of coastal ecosystems. We observed that the large majority of trace elements little or no monitored with Posidonia oceanica showed an equivalent to higher spatial variability than elements classically monitored with that species. We also showed that the spatial variability could be associated to specific anthropic activities like agriculture (Mo), mining (Sb), storage and refinement of oil products (V), or the presence of harbours and major urban centres (Sn, Bi). Their monitoring, along with the one of trace elements classically studied in the Mediterranean, turns out to be essential. In addition, the in-depth study of the contamination state of the Calvi Bay (Northwestern coast of Corsica, France), enabled us to define (or re-define) this site as a reference site for the monitoring of the chemical pollution by trace elements in the Northwestern Mediterranean. We further studied the physiological mechanisms of accumulation, storage and excretion of trace elements by Posidonia oceanica. In situ contamination of seagrass bed portions allowed us to model the rapid kinetics of accumulation of contaminants by Posidonia oceanica shoots. Compartments of the plant answered differently to pollutant exposures. So, adult and senescent leaves assimilated pollutants less rapidly than young actively growing leaves. Trace elements, once accumulated, could be redistributed between the plant compartments, notably towards the rhizomes-roots systems buried in sediments. Our results experimentally showed that these below-ground organs could therefore play the role of biological archives for many elements. At the end of periods of exposure to pollutants, kinetics of decontaminations of Posidonia oceanica shoots were relatively fast and depended notably on the duration of the exposure to trace elements, on their toxic or essential character and on the studied compartment. We concluded that Posidonia oceanica was a sensitive bioindicator for the monitoring of the past and present coastal pollution by trace elements. We showed that Mytilus galloprovincialis efficiently accumulated trace elements of environmental emerging concern as well as elements classically studied with this bioindicator species. The physiology of mussels further conditioned their answers to pollutant exposures. Their reproductive cycle dissolved trace element concentrations during the massive production of gametes and conducted to differences more or less important between individuals of both sexes. The conservative character of the distribution of trace elements between the different body compartments of Mytilus galloprovincialis suggested an important physiological regulation of their internal levels. Finally, the size of mussels used in this study, harvested from an aquaculture farm, did not noticeably influence inter-individual concentrations, all mussels of a same rope having approximately the same age. In conclusion, this study enabled to improve and enlarge our state of knowledge about the monitoring of the pollution of the Mediterranean coastal environment by trace elements. In particular, both Mytilus galloprovincialis and Posidonia oceanica showed to be good candidates for the monitoring of trace elements of environmental emerging concern. [less ▲]

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See detailTime delays in gravitationally lensed quasars
Eulaers, Eva ULg

Doctoral thesis (2012)

Starting with a concise introduction on gravitational lensing, time delays between lensed quasars and its importance as a cosmological probe to estimate the Hubble constant, we present our contribution to ... [more ▼]

Starting with a concise introduction on gravitational lensing, time delays between lensed quasars and its importance as a cosmological probe to estimate the Hubble constant, we present our contribution to this domain. In a first part, we explain the details of the Numerical Model Fit, a method to estimate time delays between two or more lensed quasar images. We apply this technique to the light curves of 11 lensed quasars with known time delays in order to analyse these published delays in a more homogeneous way. Some results can be confirmed, but others prove to be unreliable. The second part is devoted to the most recent results of our contribution to the COSMOGRAIL collaboration. We briefly summarize the data reduction and analysis tools before the presentation of the photometry and time delay analysis of 6 lensed quasars. On top of the confirmation of time delays in two objects, SDSS J1206+4332 and SDSS J1650+4251, we are the first to measure the time delay in three doubly lensed quasar systems: HS 2209+1914, SDSS J0903+5028, and SDSS J1155+6346. The time delay analysis of the well-known quadruply lensed quasar PG 1115+080 reveals interesting elements, and asks for further investigation of longer light curves. [less ▲]

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See detailGRH et Organisation du travail dans les centres d'appels délocalisés au Maroc
Makkaoui, Mohamed ULg

Doctoral thesis (2012)

Considered, rightly or wrongly, as "new factories of the future", call centers generate more interest for both researchers and professionals. Their human aspects in general and their HR practices in ... [more ▼]

Considered, rightly or wrongly, as "new factories of the future", call centers generate more interest for both researchers and professionals. Their human aspects in general and their HR practices in particular is a rich field for investigations, due to the importance of their technical and social systems in their performance or their sustainability. The question of the choice of HR practices is the focus of this work devoted to the issue of HRM and work organization in offshoring call centers. It is based on nine case studies representing a varied typology of Moroccan call centers sector and three typical -ideal models adopted by them (Hard, Soft or hybrid). The choice of a model or another comes, initially, from a business strategy, a targeted market segment and a given level of outsourced value-added activities. The alignment between strategy and organization of the call center operates for each model to incorporate the same operational requirements (customer-agent interactions, colleagues) and its internal labor market. This variable is the link between work organization and HR strategy adopted. Referring to an HR model or another is conditioned by the intervention of the principal who greatly influence the decisions of managers as well as decision makers. [less ▲]

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See detailIMPACT DE LA STEAM EXPLOSION ET DE L’HOMOGENEISATION SUR LES PROPRIETES PHYSICOCHIMIQUES ET L’HYDROLYSE ENZYMATIQUE DE LA CELLULOSE
Jacquet, Nicolas ULg

Doctoral thesis (2012)

In the economic and energetic context of our society, it is universally recognized that an alternative to fossil fuels and oil based product will be needed in the nearest future. A potential solution is ... [more ▼]

In the economic and energetic context of our society, it is universally recognized that an alternative to fossil fuels and oil based product will be needed in the nearest future. A potential solution is to develop second generation biofuel and biobased product that utilizes non-food plant materials. The major component of these materials is lignocellulose, which is a complex composed by widely available biological polymers such as cellulose, hemicelluloses and lignin. This thesis is a part of this approach and is focused on a well-define part of these materials: the cellulose. The first part of this work was focused on the impact of two pretraitements (steam explosion and homogenization) on physico-chemical properties and hydrolysis yield of pure cellulose fiber. In contrast with literature, results obtained showed that moderate steam explosion treatments did not appear to improve the enzymatic hydrolysis yield of the cellulose fibers. In Parralel, a model that predicts the effect of the intensity of the steam explosion treatment in correlation with temperature and time was assessed. Links between this model and the evolution physico-chemical properties of the cellulose during pretreatment and cellulose hydrolysis yield were established In a second way, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. Regarding the homogenization, it was shown that homogenization increase significatively the cellulose hydrolysis (from 25 to 100%). Results highlights potential of this technology to be used as a pretreatment Finally, enzymatic hydrolysis step has been studied in order to improve cellulose hydrolysis and to obtain high concentrated hydrolysate. In this way, two methods based on successive addition of enzyme and substrate were assessed [less ▲]

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See detailExtending Donor Pool with Donation after Cardiac Death in Kidney and Liver Transplantation:What is the Price to Pay?
Le Dinh, Hieu ULg

Doctoral thesis (2012)

Through a series of clinical studies, this thesis aims to clarify the contribution of donation after cardiac death (DCD) to the deceased donor (DD) pool and results of kidney and liver transplantation ... [more ▼]

Through a series of clinical studies, this thesis aims to clarify the contribution of donation after cardiac death (DCD) to the deceased donor (DD) pool and results of kidney and liver transplantation coming from this donor source in Liège and Belgium. Additionally, an adapted DCD Maastricht classification is also discussed. Chapters 2.1 and 2.2 summarize the DCD procurement and transplant activity in Liège and Belgium from 2000 to 2009 with an update on data up to 2011. In Liège, DCD really contributes to the DD pool and boosts the transplant activity of the center in both kidneys and livers by on average 30%. By contrast, the steady rise in DCD activity in Belgium does not lead to major increase in the DD donation and transplantation. In other words, some kind of donor-type redistribution within the DD pool might occur. Chapters 2.2, 3.1, and 3.2 discuss the results of kidney transplantation (KT) from DCD. We demonstrate that Liège‟s experience is comparable to the national level in Belgium and does not differ from the general results in the world with regard to early graft dysfunction, medium-term graft function, graft and patient survival. The excellent results of DCD-KT are attributed to the relatively short warm and cold ischemia, favorable donor factors, and the role of hypothermic machine perfusion (in Belgian series). Chapters 4.1, and 4.2 discuss the results of liver transplantation (LT) from DCD. Liège‟s results are encouraging and apparently as good as those from donation-after-brain-death LT because of short warm and cold ischemia times. Belgian results show an increased incidence of primary non-function and ischemic cholangiopathy which is in agreement with previously published data. Chapter 5 proposes an adapted DCD Maastricht classification which maintains the original categories 1 to 4 that are now well-known and widely accepted, and adds a fifth category, so-called „DCD after euthanasia‟. Each category is divided into two or three sub-categories: sub-category A is linked to longer warm ischemia (and worse results) than sub-category B; and B versus C, respectively. In addition, sub-categories A (2A, 3A, 4A, and 5A) are mostly linked to DCD processes occurring in the ICU, which helps to understand and memorize this classification. By keeping the original skeleton of the 1995 Maastricht classification, room is left to add new sub-categories in the future, if deemed clinically relevant. [less ▲]

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See detailS’engager dans un atelier-théâtre : vers une recomposition du sens de l’expérience
Brahy, Rachel ULg

Doctoral thesis (2012)

Dans cette thèse, nous traitons des animations théâtrales mises en place par les compagnies de théâtre-action situées en Communauté française de Belgique. La question centrale qui nous guide est celle des ... [more ▼]

Dans cette thèse, nous traitons des animations théâtrales mises en place par les compagnies de théâtre-action situées en Communauté française de Belgique. La question centrale qui nous guide est celle des formes concrètes que revêtent les pratiques contemporaines d’animation. Par ailleurs, nous nous intéressons également aux changements survenus dans l’exercice de l’activité. En effet, les premières compagnies à se revendiquer du « théâtre-action » naissent autour des mouvements de 1968. D’abord perçues comme expérimentales, ces pratiques pourraient bien, aujourd’hui, être considérées comme désuètes, à tout le moins, déconnectées des problématiques contemporaines. Notre enquête s’ouvre à partir de cette idée et nous montrons ensuite comment s’est acheminée une progressive reconversion des pratiques. En privilégiant le cadre théorique de la sociologie pragmatique française (et plus exactement, celui des « régimes d’engagement » établi par Laurent Thévenot) nous détaillons les modalités d’engagement dans un « atelier-théâtre ». Alors qu’originellement, le dispositif théâtral privilégiait les formats de la revendication « critique » et mobilisait prioritairement des personnes issues du monde ouvrier, on constate aujourd’hui une relation forte entre les compagnies de théâtre-action et le monde de l’accompagnement social. Cette proximité produit inévitablement un déplacement signifiant qui, pourtant, ne s’apparente pas à une totale superposition des secteurs. L’analyse de notre matériel empirique (composé d’entretiens et d’observation ethnographiques) témoigne d’une irréductible spécificité inhérente à l’engagement dans le monde du théâtre et de la fiction. Ainsi, les manières de prendre part à un monde commun et de s’engager en public sont repensées. En définitive, nous dégageons l’existence d’un « espace public esthétique » et précisons les voies par lesquelles un « engagement en présence » permettrait d’y accéder. [less ▲]

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See detailLa littérature scientifique dans la formation des bioingénieurs à Gembloux. Vingt années d'évolution du concept d'Information Literacy
Pochet, Bernard ULg

Doctoral thesis (2012)

In the education of bioengineers at Gembloux, the concept of information literacy was chosen as a guide for information literacy education. This concept describes a set of skills that allow individuals to ... [more ▼]

In the education of bioengineers at Gembloux, the concept of information literacy was chosen as a guide for information literacy education. This concept describes a set of skills that allow individuals to recognize an information need and enable them to locate, evaluate and use information needed. The concept of information literacy has evolved over the last two decades. This essay traces, through five articles and a review of the literature on the subject, the evolution of the concept. It also presents ways to implement information literacy education with a methodological approach, starting by the identification of the need of information to solve a problem to the production of a scientific communication (a homework, a conference, a scholarly paper...). This work addresses also the question of the relative invisibility of the concept of information literacy outside information specialists such as librarians. The major objective is to demonstrate that information literacy education is going well beyond the library. The skills involved are also intellectual, social and cultural skills. They include media and new information technologies and are not limited to technical or technological skills. Information literacy has become an autonomous discipline, with specific content, evolving, to talk about a didactic. Information literacy courses held in Gembloux should be considered as tools to improve the training of bioengineers and particularly the quality of their scientific publications. [less ▲]

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See detailStructure et fonction des communautés phytoplanctoniques en milieux côtiers marin et lagunaire (Méditerranée – Corse) dans une optique de gestion
Garrido, Marie ULg

Doctoral thesis (2012)

Les écosystèmes côtiers contribuent de manière importante à la production primaire des océans. De par leur position géographique, ils sont particulièrement sensibles à l’eutrophisation. Le compartiment ... [more ▼]

Les écosystèmes côtiers contribuent de manière importante à la production primaire des océans. De par leur position géographique, ils sont particulièrement sensibles à l’eutrophisation. Le compartiment phytoplanctonique y joue un rôle prépondérant au regard de sa position dans la chaîne tropique, mais également en termes de diversité. Il est également capable d’intégrer et/ou de refléter les changements environnementaux qui s’opèrent à court, moyen et long terme. Cette thèse vise à renforcer les connaissances sur la dynamique et la fonction des communautés phytoplanctoniques par rapport aux conditions environnementales dans deux écosystèmes côtiers, en utilisant des techniques traditionnelles comme la microscopie, l’HPLC et d’autres plus récentes comme le Phyto-PAM et la FluoroProbe. Le littoral corse a été choisi comme site d’étude. En effet, ses 1 047 km de côtes regorgent d’écosystèmes particulièrement dynamiques, d’une richesse biologique importante et de zones d’interfaces productives (e.g. structure frontale, milieu lagunaire). Malgré cela, il existe peu de données concernant la dynamique et la fonction de ces micro-algues, aussi bien en milieu marin côtier que lagunaire. Une fréquence d’échantillonnage appropriée à l’échelle d’observation a été utilisée selon les écosystèmes étudiés et le type d’étude menée (in situ ou expérimentale), allant de prélèvements mensuels à des prélèvements journaliers. Dans un premier temps, nous avons poursuivi les efforts engagés depuis plusieurs années concernant l’amélioration des méthodes d’analyses spectrofluorimétriques nécessaires pour l’étude de la dynamique et l’analyse fonctionnelle des communautés phytoplanctoniques. Des recommandations concernant les conditions de conservation des échantillons (i.e. durée, température) ont été dégagées pour l’analyse au Phyto-PAM, afin d’affiner les limites d’utilisation de cet outil. Nous avons également testé l’utilisation de la FluoroProbe dans les écosystèmes côtiers en Méditerranée. Dans un second temps, nous avons étudié la variabilité spatio-temporelle des communautés phytoplanctoniques en milieu marin côtier (Calvi et Bastia) et en milieu lagunaire eutrophisé (Réserve Naturelle de Biguglia). Les résultats ont mis en avant une succession écologique et une structure des peuplements phytoplanctoniques différentes dans les deux écosystèmes marins côtiers étudiés, présentant des spécificités locales propres et comparés à l’échelle des zones côtières en Méditerranée. Nous avons démontré que des événements météorologiques pouvaient influencer les variations observées, agissant directement sur l’abondance des espèces ou indirectement sur les conditions du milieu (e.g. nutriments). Au niveau lagunaire, les actions de gestion mises en œuvre ont impacté la structure et l'efficacité photosynthétique des communautés phytoplanctoniques. Les modifications des flux hydrologiques ont exacerbé le caractère confiné de la lagune et des efflorescences successives d’espèces opportunistes et non profitables au réseau trophique supérieur ont été observées. Ces études ont permis de fournir une aide scientifique en ce qui concerne la prise de décision qui incombe aux acteurs de l’environnement et plus particulièrement les gestionnaires, dans une optique de gestion. [less ▲]

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See detailBiolixiviation de la carrolite-Application aux minerais polymétalliques de l'Arc Cuprifère du Katanga (cas de minerais de la mine de Kamoya, Kambove) en RDC
Nkulu Wa Ngoie, Guy ULg

Doctoral thesis (2012)

The present work focuses on the bioleaching of carrolite as pure mineral and application of bioleaching as an alternative technique for processing the polymetallic sulphide ores in Katanga copperbelt ... [more ▼]

The present work focuses on the bioleaching of carrolite as pure mineral and application of bioleaching as an alternative technique for processing the polymetallic sulphide ores in Katanga copperbelt (case of Kamoya deposit ores) in Democratic Republic of Congo (DRC). A preliminary study on the bioleaching of carrolite in the presence of mesophilic bacteria has highlighted the effect of the initial pH (pH = 1.5, 2.0 and 2.5), particle size (-53μm, -75+53 µm, -106+75µm), the pulp density (dp= 2.5 and 10) on the pH, the solution redox and on the dissolution performance of copper, nickel and cobalt. The results obtained at this stage showed that the initial pH, particle size and pulp density greatly influences the process of bioleaching of carrolite. The evolution of pH, solution redox and the efficiency of metals dissolution with time considering these factors indicate the importance of bacterial growth. Good bacterial activity thereby yields high metal dissolution which is being obtained at initial pH 2.0, particle size of -53μm and 2% pulp density. A second study upon the bioleaching of carrolite has allowed highlighting the metal dissolution mechanism during the bioleaching process. The evolution of the bacterial population, observations of Optical Microscope (MO), Scanning Electron Microscope (SEM), Confocal Laser Scanning Microscope (CLSM) of carrolite grains during bioleaching and spectroscopical analysis in X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) of bioleaching residues allowed us to demonstrate the role and importance of bacteria attached on the surface of carrolite grains from one hand, and ferric ions on the other hand, during the carrolite bioleaching. Strong adhesion of bacteria to the surface of the carrolite grains was observed during early bioleach stages and playing an important role in the process. This phenomenon would cause the release of ferrous ions in solution by a direct contact mechanism on the one hand and causing oxidation of ferrous ions, elemental sulfur or sulfur compounds on the other hand, compounds which would accumulate at the surface of carrolite grains. The number of free bacteria in solution increases thus promoting the oxidation of ferrous to ferric ions, which oxidize the mineral through indirect mechanism. The number of free bacteria in solution and that of attached bacteria became constant over time, suggesting a cooperative mechanism of carrolite bioleaching. Finally, a statistical study of bioleaching of polymetallic concentrate from Kamoya deposit by Taguchi methodology and analysis of variance (ANOVA) was used to investigate the effect of different physicochemical parameters (initial pH, temperature, agitation, pulp density and duration of bioleaching) on the process efficiency. The results obtained from this statistical approach showed the possibility of bioleaching application as an alternative technique for treatment of the polymetallic sulphide ores of the Katanga copperbelt in Democratic Republic of Congo (DRC) but further investigation using thermophilic bacteria should be considered to improve metal dissolution. [less ▲]

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See detailDiffractive straylight rejection system for wide field imagers. Design, performance and application to the STEREO solar space mission.
Halain, Jean-Philippe ULg

Doctoral thesis (2012)

Space-born wide field imagers have become a new tool used in the frame of Solar Physics and in particular in the field of Space Weather. One particular application is the tracking of coronal mass ejection ... [more ▼]

Space-born wide field imagers have become a new tool used in the frame of Solar Physics and in particular in the field of Space Weather. One particular application is the tracking of coronal mass ejection (CME), generated by violent eruptions on the sun’s surface, that propagates in the heliosphere. The CME brightness however rapidly decreases with the distance from the Sun. To reach a sufficient signal to noise ratio and follow CME away from the Sun, a high sensitivity is therefore required and the unwanted parasitic light (so called straylight) must be minimized. In particular, the Sun disk brightness must be occulted by a highly rejecting baffle system. A multi-edge diffractive baffle can provide a very high level of straylight attenuation for nearly collimated light source. A model of the multi-edge diffractive rejection has been implemented on the basis of the Fresnel diffraction theory. It allows the design and optimisation of such diffractive baffle as function of the instrument and observing geometries. The model was validated on a diffractive baffle mock-up, providing rejection down to an un-precedent level of 10-10 of the input flux. The model of multi-edge diffractive baffle has been applied to the specific configuration of the Heliospheric Imager (HI), on-board the NASA scientific Solar Terrestrial Relations Observatory (STEREO) mission, as part of its overall straylight reduction. The STEREO-HI baffle performance has been validated on a prototype and during the final end-to-end calibration of the flight instrument. After launch, the in-flight straylight level has been quantified, showing a very good correspondence with the on-ground measurements. The straylight evolution has also been shown to be stable during the mission, showing the baffle efficiency does not degrade with the space environment. The STEREO-HI instrument achieves a 10-13 rejection level, or greater, of the solar brightness at the detector pixel level. This instrument is the first wide field space imager viewing from outside the Sun-Earth line, and therefore able to directly follow the propagation of CME from the Sun to the Earth with a high accuracy and sensitivity. Since its launch, it provides unprecedented images and information on solar wind and CME propagation and evolution in the heliosphere. The next generation of wide-field solar imagers are under development for the ESA Solar Orbiter and NASA Solar Probe Plus missions. Their concept benefits from of the STEREO-HI front diffractive baffle system and is based on a multi-edge diffractive baffle to protect their cameras from solar disk brightness. The straylight calibration of these two instruments is in preparation and will be performed at the Centre Spatial de Liège with the tools and methods developed in the frame of the present work. [less ▲]

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See detailRegulation of water flow in the soil-root domain. New tools and methods
Lobet, Guillaume ULg

Doctoral thesis (2012)

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See detailEtude du rôle de l’Hypoxia Inductible Facteur 1 dans les cellules myéloïdes lors d'allergie des voies respiratoires
Toussaint, Marie ULg

Doctoral thesis (2012)

Adaptive Th2 immune responses play a major orchestrating role in the development of airway allergy in mammals. It is currently known that the induction of Th2 responses closely depends on the activation ... [more ▼]

Adaptive Th2 immune responses play a major orchestrating role in the development of airway allergy in mammals. It is currently known that the induction of Th2 responses closely depends on the activation of innate immunity. Through its action on innate immune cells, Hypoxia inducible factor 1 (Hif1) has been described as a major regulator of inflammatory responses. Airway allergy is a disease whose incidence is in constant increase in developed countries, and the potential implication of Hif1 in innate immune cells during the development of such disease remains currently unknown. Therefore, we were interested in the involvement of Hif1 within innate immune cells in two experimental models of allergic airway inflammation: allergic asthma and recurrent airway obstruction (RAO). Recurrent airway obstruction is one of the most frequent respiratory syndrome that veterinary equine practice has to deal with in our countries. In the case of RAO, the role of the innate immune system, representing the first line of host defense, has not been investigated so far. We have therefore looked at the potential implication of Hif1 in pulmonary innate immune cells during this disease. We have found that, upon allergenic challenge, Hif1 expression within pulmonary innate immune cells was significantly increased in RAO-affected horses in comparison to the control animals. In addition, Hif1 expression was positively correlated to the severity of clinical dysfunctions in RAO-affected horses. We have also shown that the presence of hay-derived LPS could specifically increase Hif1 expression in macrophages. As previously described in other models of inflammation, these results allowed us to show, in a model of RAO, that Hif1 plays a pro-inflammatory role in innate immune cells. Since 90% of innate immune cells of a healthy horse are macrophages, we decided to further investigate the implication of Hif1 in lung myeloid cells. In the second study, for technical reasons, we decided to focus on another model of airway allergy, namely allergic asthma. Although molecular and cellular mechanisms governing asthma development are well characterized, very few information is available regarding the mechanisms that can prevent the development of this disease in healthy subjects. The identification of such mechanisms could be key to understand the origin of development of that epidemic disease as well as to improve the strategies of prevention. We have found that mice that were specifically deficient in Hif1 within myeloid cells (Hif1αm-/-) developed significantly more allergic inflammation in comparison to control mice. We have further shown that these mice had a higher inclination to develop a Th2 response upon allergenic challenge. We then proved that the increase of antigen-specific Th2 responses in Hif1αm-/- mice was the result of increased lymph node dendritic cells migration and antigen presentation. These results suggested that a brake to DC activation by allergens was lost following deletion of myeloid Hif1. Finally, we have found that the specific deletion of Hif1 in interstitial macrophages was indeed responsible of the observed effects. Indeed, we have shown that the TLR-dependent activation of Myd88 in interstitial macrophages induced increased expression of Hif1, thereby increasing IL-10 production from interstitial macrophages. In addition, following HDM stimulation, we observed that Hif1αm-/- interstitial macrophages produced significantly less IL-10 than control interstitial macrophages. Since we have previously shown that interstitial macrophages were capable of blocking dendritic cell activation through the production of IL-10, we proposed that Hif1 was able to control the immunoregulatory functions of interstitial macrophages by regulating their IL-10 production. Our work revealed a crucial role for Hif1 in interstitial macrophages for maintaining the immune homeostasis in the lung. It also suggests for the first time that Hif1 within innate immune cells can display an anti-inflammatory role. As a conclusion, we have been able to assess the importance of Hif1 activation within innate immune cells in the regulation of airway allergy development. We have further proposed that a compartmentalization of pro- and anti-inflammatory functions of Hif1 exists in immune cells. In opposition to what we obtained in the first study and what is currently known in the literature; we have found an anti-inflammatory role for Hif1 in innate immune cells. Indeed, thanks to its role in interstitial macrophages, Hif1 can play a crucial role in the prevention of aberrant immune responses against harmless antigens by preventing allergic sensitization. Hif1 therefore plays a key role in maintaining lung mucosal immune homeostasis. [less ▲]

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See detailDynamique et perspectives de la filière cotonnière du Burundi
Gahungu, Antoine ULg

Doctoral thesis (2012)

Cotton cultivation was introduced in Burundi in 1919 under the Belgian mandate with the objective to monetize the rural economy and open the country to international trade. After independence (1962), the ... [more ▼]

Cotton cultivation was introduced in Burundi in 1919 under the Belgian mandate with the objective to monetize the rural economy and open the country to international trade. After independence (1962), the cotton crop continued to flourish as a vertically integrated chain from upstream to downstream in pursuing the objectives of job creation, import substitution and maximizing the added value generated by various cotton products. Since 1993, the cotton is in perpetual decline due to various factors both endogenous and exogenous to reach in 2009 the lowest level in its history. Its competitiveness is challenged by instability of the global market of cotton fiber, policies (subsidies) of large producers (China, India, USA, Pakistan, ...), competition from synthetic textile industry, the prices of agricultural inputs (fertilizers and phytosanitary products) and raw materials for industries, competition for food crops production factors which are already scarce and especially less remunerative producer prices. Survey work on a sample of 120 farms during three seasons (2007/2008, 2008/2009, 2009/2010) as well as interviews with various agents involved in the cotton sector have been conducted to understand the reasons of the decline of the cotton sector and see the adaptation mechanisms implemented in the segment "producers - COGERCO." It appears from these investigations that the cotton is not competitive with food crops. The price paid to growers is not motivating, production costs are expensive and factors of production become increasingly restrictive. COGERCO however, continues to subsidize cotton without benefit. In this context the majority of cotton producers combine beans or cowpeas with cotton to take advantage of subsidies (inputs, management, ...) and other benefits (loans, fields ...) that the company offers to producers without benefit to the company. The latter is in chronic deficit due to poor sector governance which is under pressure of privatization already imposed on other agro-industrial crops of the country (coffee, tea). [less ▲]

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See detailMechanical Processes of a Single Synthetic Molecular Machine Studied by AFM-based Force Spectroscopy
Lussis, Perrine ULg

Doctoral thesis (2012)

Some biomolecules are able to generate directional forces by rectifying random thermal motions. This allows these molecular machines to perform mechanical tasks such as intracellular cargo transport or ... [more ▼]

Some biomolecules are able to generate directional forces by rectifying random thermal motions. This allows these molecular machines to perform mechanical tasks such as intracellular cargo transport or muscle contraction in plants and animals. Although some artificial molecular machines have been synthesized and used collectively to perform mechanical tasks, so far there have been no direct measurements of mechanical processes at the single-molecule level. Here we report measurements of the mechanical work performed by a synthetic molecule less than 5 nm long. We show that biased Brownian motion of the submolecular components in a hydrogen-bonded [2]rotaxane -a molecular ring threaded onto a molecular axle- can be harnessed to generate significant directional forces. We used the cantilever of an atomic force microscope to apply a mechanical load to the ring during single-molecule pulling-relaxing cycles. The ring was pulled along the axle, away from the thermodynamically favoured binding site, and was then found to travel back to this site against an external load of 30 pN. Using fluctuation theorems, we were able to relate the measurements of the work done at the level of individual molecules to the free energy change measured previously by ensemble measurements. Finally, we used dynamic single-molecule force spectroscopy to probe kinetic information of the interaction between the molecular ring and the preferred binding site. The results also demonstrate that AFM-based single-molecule force spectroscopy, which has been widely used to investigate the mechanochemical behaviour of (bio)macromolecules, can be applied to a molecule that is less than 5 nm in its extended form. [less ▲]

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See detailThe effects of a cadmium exposure on poplar plants: A combined proteomic, physiological and biochemical approach to unravel stress-responses in poplar.
Kieffer, Pol ULg

Doctoral thesis (2012)

The industrial revolution in the 1800s and the subsequent industrialization had the consequence of an anthropogenic release of many organic and inorganic pollutants. Among these pollutants, cadmium is ... [more ▼]

The industrial revolution in the 1800s and the subsequent industrialization had the consequence of an anthropogenic release of many organic and inorganic pollutants. Among these pollutants, cadmium is very problematic due to its high toxicity. It can induce significant damage to the vegetation and an accumulation in farmland introduces the pollutant into the food chain. This creates a possible major health risk for humans. Poplar plants, as a member of the Salicaceae family, seem to possess a certain tolerance to this toxic metal and accumulate significant amount in their aerial parts, making poplar a possible candidate for phytoremedation. The metabolic and physiological impact of cadmium have been studied as well in field trials as in controlled laboratory conditions, but mostly in clearly targeted studies focusing on a few key aspects. The recent advent of more global techniques such as transcriptomics and proteomics, make it possible to obtain new results. In the thesis presented here, a proteomic study of the short-term and long-term effects of cadmium on poplar leaf and roots metabolic processes in controlled laboratory conditions was carried out. With the help of this technique, complemented with biochemical and physiological approaches and with morphological observations, it was possible to obtain results on the stress-coping mechanisms underlying an acute first response, but also on the more general adaptation mechanism which make it possible for the poplar plants to tolerate significant amounts of cadmium. Results showed a negative impact on important cell processes like photosynthesis and ATP synthesis and the antioxidant system, explaining the impaired growth. Similar results could be obtained in roots, although the stress seemed much more acute, as evidenced by the stronger accumulation of typical stress proteins (i.e. heat shock proteins). In a final set of experiments a controlled combination of two stresses (cadmium and nonlethal chilling stress; 4°C) allowed separating specific cadmium responses from a more general stress response. Cadmium had a much more severe impact on plant survival when combined with an additional constraints. In this present work, the procedures, results and conclusions obtained are presented in detail. [less ▲]

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See detailModélisation de la transition solide-fluide dans les géomatériaux. Application aux glissements de terrain.
Prime, Noémie ULg

Doctoral thesis (2012)

Geomaterials are present in nature in many forms : solid soil or rock, soft clay, almost liquid mud, etc. Geomechanics deals with the understanding the solid behavior of geomaterials. However, solid ... [more ▼]

Geomaterials are present in nature in many forms : solid soil or rock, soft clay, almost liquid mud, etc. Geomechanics deals with the understanding the solid behavior of geomaterials. However, solid ground can happen, under specific external conditions, to turn into fluid : as for example during mudflows or debris flows. In such a context, our work concerns, in a general way, solid-fluid transition in geomaterials behavior and the development of a constitutive model describing both the solid phase, fluid phase, and the transition between the two. In this framework, we chose to carry out calculations with the FEMLIP numerical method (Finite Element Method with Lagrangians Integration Points) which has shown a strong potential to describe a wide variety of behaviors (including history dependent behavior), in a unique model. Having implemented and validated the first elasto-plastic law in Ellipsis (FEMLIP based code), we have introduced in this code the solid-fluid transition model. This last is based on the evolution, at the failure state detected by the second order work criterion, of the solid elasto-plastic behavior towards a viscous fluid behavior, exhibiting a yield stress. After validation of the solid-fluid transition model in homogeneous cases (considering Plasol elasto-plastic law and Bingham viscous one), we applied this model to the modeling of Sarno and Quindici mudflows (Italy, 1998). [less ▲]

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See detailReflection amplifiers in self-regulated learning
Verpoorten, Dominique ULg

Doctoral thesis (2012)

The project studies how presenting task-related, performance and social context indicators as prompts for reflection to learners can best support meta-learning in self-regulated-learning settings. Meta ... [more ▼]

The project studies how presenting task-related, performance and social context indicators as prompts for reflection to learners can best support meta-learning in self-regulated-learning settings. Meta-learning, for the purpose of this research, denotes the competency to make the experience of learning an object of attention, an object of reflection and an object of conversation. Reflection amplifiers are artefacts that trigger, ease and enhance this activity. Though it strongly relies on and refers to the research dedicated to the germane concept of metacognition, the thesis prefers to use the term "meta-learning" because this involves more than cognition, embracing aspects of the learning experience like semantic intensity, affective dimensions, social relations or context appraisal. Also, the term meta-learning it is more easily understood by practitioners (students and teachers). The PhD-work entails analysing existing solutions and prototyping new tools, investigating their relevance and use conditions, and assessing their effects on meta-learning. The research also includes the development of a pedagogically-grounded rationale and a set of guidelines for the design of such artefacts. [less ▲]

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See detailValorisation du savoir local pour une cogestion conservatoire de l'arganeraie marocaine
Aziz, Larbi ULg

Doctoral thesis (2012)

L’arganeraie est un écosystème particulier disposant d’une biodiversité animale et végétale spécifique dont l’élément central est l’arganier. C’est un arbre multifonctionnel du fait des usages multiples ... [more ▼]

L’arganeraie est un écosystème particulier disposant d’une biodiversité animale et végétale spécifique dont l’élément central est l’arganier. C’est un arbre multifonctionnel du fait des usages multiples qu’en font les populations locales. Il constitue l’élément central du système agraire local car il a configuré et rythmé la vie et les activités des populations. Celles-ci, disposant de nombreux droits de jouissance au niveau de la forêt d’arganier, ont mis au point une gestion communautaire régulant l’accès et le contrôle aux ressources. Cette gestion et le fonctionnement du système agraire témoignent de la possession par ces populations de savoirs et savoirs faire locaux qui perdurent de génération en génération. Toutefois, ces savoirs n’ont pas été assez étudiés pour pouvoir les valoriser. Or, depuis des décennies, les savoirs locaux font l’objet d’intérêt croissant à l’échelle internationale, tant au sein de la communauté scientifique que des ONG internationales. C’est ainsi que cette recherche vise à identifier et à valoriser ces savoirs dans le cadre d’une stratégie de cogestion conservatoire, intégrée et participative de l’arganeraie. Comme outils d’investigation, nous avons eu recours à l’observation et à l’entretien semi directif. Ainsi, nous avons interrogé une centaine de personnes (hommes et femmes) relevant des communes rurales d’Aguerd et de Tidzi (région d’Essaouira). Nous avons aussi interrogé des acteurs institutionnels (agriculture, eaux et forêts, agences, recherche et ONG) en vue de dégager leurs points de vue. Pour l’analyse des données, nous avons utilisé trois méthodes complémentaires: l’analyse descriptive, l’analyse du contenu et l’analyse comparative. Les savoirs locaux identifiés ont été analysés notamment au regard du savoir scientifique. Les résultats ont été comparés entre les deux communes, et au sein de chaque commune ces savoirs sont différenciés selon le genre. Par ailleurs, nous nous sommes basés sur le cadre analytique de Berkes (1999) et sur le modèle IAD Framework d’Orstom (1994) pour pouvoir comprendre la problématique traitée dans toutes ses facettes. Ainsi, nous avons identifié des savoirs relatifs aux trois éléments du système agraire local et à leurs interactions ainsi que ceux relatifs au mode de gestion de la forêt d’arganier et la vie culturelle de la population enquêtée (rites, recettes cosmétiques et de la pharmacopée traditionnelle,..). Il en ressort que l’ensemble de ces savoirs renvoie à une meilleure adaptation de la population à son milieu, à une fine connaissance de l’écosystème et de son fonctionnement. D’autre part, ces savoirs, différenciés selon le genre, montrent que les paysans ne raisonnent pas l’écosystème de manière sectorielle mais dans sa globalité. Par ailleurs, les modes de transmission de ces savoirs sont l’observation, la participation et l’imitation. Cependant, certains de ces savoirs sont en train de disparaître suite aux changements que connaît la zone. Ils doivent donc être requalifiés comme patrimoine culturel à respecter, à conserver, à en contrôler l’accès et à valoriser. D’un autre côté, nos résultats ont montré que l’engouement pour les produits de l’arganier et la flambée de leurs prix à partir de la fin des années 1990, ont entrainé des conséquence socio-économiques au niveau de la zone : changements au niveau des représentations et des comportements des locaux vis-à-vis de l’arbre, apparition de nouveaux acteurs s’enroulant dans des collectifs qui ont beaucoup évolué, mis en place d’un marché peu structuré et pas assez profitable aux locaux, érosion du savoir local, apparition de nouveaux modes d’alimentation, disparition de coutumes et de traditions, etc. ce qui nous a poussé à plaider pour la conception d’une stratégie de conservation de l’arganeraie. Or, de nombreuses actions ont été menées par certains acteurs dans ce sens. Malheureusement, ces efforts sont restés sectoriels, éparpillés, non intégrés et ne prenant pas en compte les nouvelles dynamiques en place. C’est ainsi que nous avons élaboré une proposition de stratégie de cogestion conservatoire de l’arganeraie faisant participer l’ensemble des acteurs, particulièrement les populations locales en valorisant leurs savoirs. Elle se veut cohérente, intégrée et reposant sur les axes suivants : la participation et la concertation entre les différents acteurs, l’assurance d’une bonne gouvernance locale (au sein des structures et entre les partenaires), l’appropriation de l’aménagement de l’arganeraie en valorisant les savoirs locaux identifiés et en appuyant la structure de l’agdal, la structuration du marché et la relocalisation de la plus-value (IGP argane), la promotion du tourisme rural, la réalisation d’actions d’accompagnement. Par ailleurs, cette stratégie doit s’inscrire dans le cadre d’un développement local plus global pour pouvoir prendre en compte l’aspect temporel dans les évolutions des dynamiques en cours. [less ▲]

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See detailOptimisation de l'utilisation des ressources en eau du bassin du Kou pour des usages agricoles
Traore, Farid ULg

Doctoral thesis (2012)

Water is a priceless natural resource very sensitive to external factors and environmental degradation. It becomes more valuable as competing uses multiply. Therefore, integrated and cooperative water ... [more ▼]

Water is a priceless natural resource very sensitive to external factors and environmental degradation. It becomes more valuable as competing uses multiply. Therefore, integrated and cooperative water resources management is essential within a watershed. The Kou watershed (Burkina Faso) has significant water resources which are divided between domestic (water supply, etc.), agricultural (irrigation) and industrial uses. The hydro-agricultural context of the Kou watershed is marked by a perennial river, along which are located several agricultural areas. Over time, once satisfying water needs degraded to irrigation water deficits, mainly due to a reduction in water supply and an increase in irrigated farmland. Irrigation water deficits are mostly encountered in the more downstream agricultural areas. The socio-economic context is characterized by a growing trend for highly profitable and water consuming crops (e.g. banana). This further increases the irrigation water deficits, as well as the upstream-downstream water-sharing inequalities. In the context of the study area, the main factor that may influence the agricultural water withdrawals is the farmers' production system. The main hypothesis of the study was to verify whether these agricultural production systems could be the lever to optimize irrigation water use. The methodology of the study was to provide a sufficiently accurate knowledge of the water management system, so that improvements could be proposed. A decision support tool based on the ‘multi-agent systems’ approach (MAS) was developed in order to provide an answer to the problems of the study area’s water management by simulating management scenarios. The findings of the study showed (using the MAS tool) that through actions on agricultural production systems it is possible to optimize irrigation water withdrawals. Within the production systems, it is mainly changes in irrigation practices that have led to an optimization of the water management. Finally, the study showed that the use of MAS in resolving agricultural water management issues in the Kou watershed could be the starting point for a new approach in water management. This approach allows the effective integration of the consequences of farmers' decisions regarding water management. More generally MAS-based natural resources management tools provide a common representation of the environment within a model that can help raise awareness concerning a better management of these natural resources. [less ▲]

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See detailLong-term study of biogenic volatile organic compound exchanges in a forest ecosystem
Laffineur, Quentin ULg

Doctoral thesis (2012)

The terrestrial biosphere, especially forest ecosystems, emits large quantities of volatile organic compounds (VOCs) which have a significant impact on the atmosphere’s chemical and physical ... [more ▼]

The terrestrial biosphere, especially forest ecosystems, emits large quantities of volatile organic compounds (VOCs) which have a significant impact on the atmosphere’s chemical and physical characteristics. In particular, VOCs are precursors in the formation of ozone and sec-ondary organic aerosols. Isoprene and monoterpenes dominate the total VOC emissions, and methanol is one of the most abundant atmospheric VOCs due to its longer half-life than the other two. The main objective of this thesis was to investigate (using the eddy covariance technique and a proton-transfer-reaction mass spectrometer) the mechanisms of VOC (isoprene, monoterpene and methanol) emission and/or deposition at the scale of a temperate climate forest ecosystem (Vielsalm, Belgium) comprising several species (Fagus sylvatica, Abies alba, Picea Abies and Pseudotsuga menziessi). The eddy covariance technique is very suitable for studying VOC emission/deposition mechanisms at ecosystem level as it does not interfere with the functioning of the ecosystem and it has very good temporal resolution (half an hour). It was used for several months at the Vielsalm site without any major interruption to the measurements. The first measurement period ran from early July to late November 2009 and the second from late March to late November 2010. As well as measuring the VOC exchanges by eddy covari-ance, the climate parameters controlling the exchange mechanisms were also measured. During both these periods the methanol, acetaldehyde, acetone, isoprene, methyl vinyl ke-tone/methacrolein, monoterpene, acetic acid (2010) and formic acid (2010) fluxes were meas-ured. The highest emission levels observed were isoprene and monoterpenes along with methanol, which unlike the first two also showed depositions. The thesis therefore naturally focused on studying these three fluxes, in view of the important role played by these three compounds in atmospheric chemistry and hence the scientific community’s interest in refining the parametrisation of these compounds’ ecosystem/atmosphere exchange models. The study of the isoprene, monoterpene and methanol fluxes has been written up in three original articles which form the main body of this thesis. Because of the heterogeneity of the ecosystem studied, the first essential study concerned the identification of VOC-emitting species. This was done with the aid of a flux footprint model combined with a map of the species occurring on the site. This analysis showed that the main monoterpene emitter was Fagus sylvatica followed, to a lesser extent, by Abies alba, Picea Abies and Pseudotsuga menziessi. In contrast to the literature, the analysis showed Abies alba to be a probable isoprene emitter but the presence of Picea Abies, a known isoprene emitter, ruled out absolute certainty on that point. The isoprene fluxes were observed by day only, unlike the monoterpene fluxes which were observed both day and night. Diurnal flux analysis clearly showed temperature and light to be the two main variables controlling emissions. Combining this analysis with a study of the close relationship between isoprene/monoterpene emissions and photosynthesis revealed the plants’ de novo biosynthetic production mechanisms, an original aspect at ecosystem scale. From the occurrence of nocturnal monoterpene emissions it was possible to determine that de novo monoterpene production emitted directly into the atmosphere (as in the case of isoprene) was not the only source of the emissions observed. Withdrawals from monoterpene sinks located in plant organs or in the soil can also be monoterpene sources. Studying the relationship between isoprene/monoterpene fluxes and light, distinguishing between cloudy and sunny conditions, showed that for the same light intensity the emissions were higher in cloudy con-ditions than in sunshine. Similarly, a study of the relationship between isoprene fluxes and photosynthesis in cloudy/sunny conditions suggested that de novo isoprene production is greater in leaves above the canopy than in leaves within the canopy. Long-term measurement of isoprene and monoterpene emissions enabled seasonal changes in the mechanisms observed to be studied and more fully understood. As well as providing an understanding of the mechanisms, this research also resulted in quantification of the seasonal changes in the key parameters for modelling isoprene/monoterpene emissions. Methanol exchanges were generally positive (emissions) by day and negative (depositions) at night. Overall, methanol depositions were predominant in summer and autumn but in the mi-nority in spring. On average, the Vielsalm site behaved like a methanol sink, which contradicts all the other research published to date. An original model was developed for identifying the mechanisms responsible for short-term and long-term methanol emissions/depositions. The consistency between the measurements and the model simulations suggested that the main processes controlling methanol exchanges in summer could be attributed, in the short term, to (water-soluble) methanol adsorption/desorption occurring in the films of water on leaf surfaces and/or on the soil surface and, in the long term, to methanol destruction by a biological and/or chemical degradation process also occurring on the surface of leaves and/or the soil. A study of the difference between the measurements and the model, in spring, indicated the possibility of biosynthetic methanol production by the plants. This production was apparently controlled mainly by temperature, but it could not be shown in summer when methanol adsorption/desorption processes dominated. The literature on ecosystem-atmosphere exchanges of isoprene, monoterpenes and, to a lesser extent, methanol is extensive. Nevertheless, what makes this research original is the spatio-temporal scale used. We are in fact working at ecosystem scale, and not at leaf or branch scale as in most other cases. Moreover, our measurements cover a timescale from half an hour to a full growing season, which is rarely found in the literature. This has resulted in a better under-standing of these compounds’ production and exchange mechanisms. To be precise, the methanol flux study is currently unique in its description and understanding of the deposition mechanisms. [less ▲]

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See detailAlternative possible à la production traditionnelle du coton en Afrique dans une perspective de développement durable? Le cas du système de production biologique et équitable au Mali
Dembele, Kouloumegue ULg

Doctoral thesis (2012)

SUMMARY The general objective of this work is to analyze the viability of the culture of organic fair trade cotton in comparison with that of conventional cotton. The study was conducted with a sample of ... [more ▼]

SUMMARY The general objective of this work is to analyze the viability of the culture of organic fair trade cotton in comparison with that of conventional cotton. The study was conducted with a sample of 45 farms with 15 farms per system, and following a systemic approach at three levels: the land of cotton cropping systems based on cotton and across the operation. At the cotton, whatever the socio-economic producer, cotton compared to conventional cotton has lower average yields, work time higher and smaller plots (0.85 ha production organic fair against 2.35 and 1.76 ha respectively in conventional production calendar and thresholds. organic fair trade cotton generates less revenue because of smaller plots. Nevertheless, the cotton is organic fair identified two broad categories of farms: farms with high levels of resources have an important livestock farms and poor with little means of production, for which the organic fair trade cotton is one of the few alternatives for income money. It should be noted that the level of these poor farms, it is often women and dependent operations manager who practice organic cultivation of cotton. Only farms with high level of resources that have a herd can derive significant profits from the cultivation of organic fair trade cotton. The alternative organic fair this effect allows access to land and access to the culture of cotton formerly marginalized groups, including women, unlike conventional cotton where only the manager manages the cultivation of cotton. There is thus improving the status of women. However, the lack of sustained management of soil fertility and nutrient compromises obtaining better yields - which is a key success factor to be and remain competitive. Level of cropping systems, comparative analysis of the performance of cropping systems confirms that productivity and valuation levels of the working day cultures and cultivation systems based on organic fair trade cotton are lower than obtained by conventional production. At the farm level, conventional production systems produce between 29% (SPCca) and 43% (SPCs) more grain from the organic production system. Reflecting the fragility of food security in the region in case of massive conversion to organic production. Regarding environmental sustainability, it appears that the most important contribution of organic cotton is safe for human health and the environment of the inputs used. [less ▲]

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See detailFirst-principles and experimental studies of hexagonal YMnO3 single crystals and epitaxial films
Prikockyte, Alina ULg

Doctoral thesis (2012)

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk ... [more ▼]

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk and in thin film forms. Yttrium manganite belongs to the class of ABO3 compounds. Most theoretical studies of ferroelectricity to date were concentrated on cubic perovskite ABO3. Yttrium manganite is hexagonal and is an improper ferroelectric. We were interested to study theoretically and experimentally how these two features behave in thin film form. Our study is organized as follows. [less ▲]

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See detailDevelopment of a transmission model of Murid herpesvirus 4
François, Sylvie ULg

Doctoral thesis (2012)

Gammaherpesviruses are the archetype of persistent viruses that have been identified in a series of animals ranging from mice to man. To date the study of transmission of these viruses in natural ... [more ▼]

Gammaherpesviruses are the archetype of persistent viruses that have been identified in a series of animals ranging from mice to man. To date the study of transmission of these viruses in natural condition has been limited by the fact that no experimental transmission model exists. Establishment and characterization of a model of transmission are therefore critical points to evaluate strategies of interference with the epidemiological cycle of gammaherpesviruses. We are studying Murid herpesvirus 4 (MuHV-4) which has originally been isolated from naturally infected bank voles (Myodes glareolus). Although serological data indicate that closely related strains are present in wood mice (Apodemus sylvaticus) and domestic mice (Mus musculus), no experimental transmission of MuHV-4 has been demonstrated in laboratory mice, the classically used in vivo model. The objective of this work was therefore to fill this gap. In a first study, we performed a comparative characterization of the infection by MuHV-4 in mice and bank voles. Our results showed that the infectious process, the pathology and the latency establishment are similar in the two species, even if replication is quantitatively lower in bank voles than in mice. It therefore appeared that, Mus musculus represents a suitable host for studying gammaherpesvirus pathogenesis with MuHV-4. These results have been published in Journal of General Virology (J Gen Virol. 2010 Oct;91(Pt 10):2553-63). In a second study, thanks to in vivo imaging, we have been able to observe, for the first time, transmission of MuHV-4 in mice. We firstly showed that MuHV-4 reexcretion occurs in the genital tract of female mice at a period by which latency is considered as established. Ex vivo imaging, histology and PCR allowed us to demonstrate the presence of viral genomes in vaginal tissues and to localize viral replication at the external border of the vagina. We also demonstrated the transient and repetitive presence of infectious viruses in the vaginal cavity. Secondly, we demonstrated the implication of sexual steroid hormones in this re-excretion process. Indeed, we analyzed the infection of untreated mice, ovariectomized mice and ovariectomized mice complemented with estrogens and/or progesterone. These analyses revealed a positive role of estrogens in the observed re-excretion. Finally, based on these results, we tested MuHV-4 transmission in mice by creating different epidemiological conditions. In the conditions tested, vertical transmission did not occur, nor did horizontal transmission between individuals of the same gender. In contrast, we were able to observe sexual transmission to naïve males by serology, in vivo imaging and quantitative PCR. In conclusion, this work has on one hand demonstrated the quality of mice as an in vivo model for MuHV-4 studies and, on the other, it has shown for the first time the existence of re-excretion and sexual transmission of MuHV-4 amongst laboratory mice. The results of this work should therefore have implications for the study of gammaherpesviruses, but also more generally for the study of sexually transmissible infections. [less ▲]

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See detailLe nationalisme algérien et ses diverses expressions dans l'immigration en France métropolitaine entre 1945 et 1965
Abssi, Marion ULg

Doctoral thesis (2012)

L'auteur traitre du combat des immigrés algériens pour l'indépendance de leur pays d'origine depuis le sol métropolitain entre 1945 et 1965, de l'implantation, de l'évolution et des méthodes d'action des ... [more ▼]

L'auteur traitre du combat des immigrés algériens pour l'indépendance de leur pays d'origine depuis le sol métropolitain entre 1945 et 1965, de l'implantation, de l'évolution et des méthodes d'action des différentes organisations nationalistes algériennes représentées en métropole, et des conflits ayant opposés les Algériens aux Européens mais aussi et surtout les Algériens entre eux durant toute la période considérée. [less ▲]

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See detailIonosphere Modelling for Galileo Single Frequency Users
Bidaine, Benoit ULg

Doctoral thesis (2012)

Nowadays the ionosphere constitutes one of the most often modelled natural media. Indeed each GPS receiver among nearly two million units sold daily throughout the world runs a model to mitigate the ... [more ▼]

Nowadays the ionosphere constitutes one of the most often modelled natural media. Indeed each GPS receiver among nearly two million units sold daily throughout the world runs a model to mitigate the ionospheric effect affecting the signal propagation from the satellites. This propagation is delayed by the free electrons in the atmosphere so that the navigation signals appear to travel distances larger than actual ones by 7 m on average. Hence this delayed propagation deteriorates the positioning accuracy deemed on a 10−m level for mass-market applications mainly involving single frequency users. Tomorrow the European navigation system Galileo will offer a new mitigation strategy to single frequency users. This strategy will rely on the NeQuick ionospheric model and associated broadcast information. To be properly implemented, it must be extensively described to future Galileo users. These users will also wonder about its effectiveness in accounting for the ionospheric delay. The PhD research covered by the present thesis has built on Belgian expertise in ionosphere monitoring to investigate the NeQuick model and its use for Galileo. It began with the collection and handling of ionosphere measurements including GPS data. It analysed various situations at different places in the world encompassing a whole year (2002). This PhD thesis provides the ins and outs of the Galileo Single Frequency Ionospheric Correction Algorithm. It gathers an algorithm description, a performance evaluation and a variant investigation. In the shape of a paper collection, it discloses many figures as visual entry-points into the juxtaposed text and includes many references allowing to dig into the details. The algorithm performances are usefully characterised both in terms of delay mitigation and positioning accuracy. On the one hand, the residual ionospheric delay reaches 31% for the chosen sites and year. On the other hand, the positioning accuracy amounts to 6 m horizontally and 9.3 m vertically. The performance evaluation allowed to emphasise several aspects of the Galileo ionospheric correction. This correction depends largely on the modelling of the topside, the upper part of the ionosphere, which hosts more complex physical processes. It owes its good performances to data ingestion, the model adaptation technique to actual measurements underlying the Galileo algorithm. It does not necessarily provide highly correlated correction levels in terms of delay on the one hand and positioning on the other. It enables the definition of alternative regional procedures following a compatible design but coping with its weaknesses. The present thesis paves the way for future work related to ionosphere modelling for Galileo single frequency users. It supplies comparative information for the algorithm assessment in the framework of successive phases of Galileo deployment. It establishes a conceptual basis for an Assisted Ionospheric Correction Algorithm (A-ICA) disseminating more flexible ionospheric information thanks to the integration of Global Navigation Satellite Systems and telecommunications. [less ▲]

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See detailEtude hydrogéologique du système aquifère du horst de Diass en condition d’exploitation intensive (bassin sédimentaire sénégalais) : apport des techniques de télédétection, modélisation, géochimie et isotopie
Madioune, Diakher Hélène ULg

Doctoral thesis (2012)

Le système aquifère du horst de Diass situé à 50 km à l’Est de Dakar (Sénégal) est soumis à des pompages intensifs depuis plus de 50 ans pour assurer en continu une demande en eau sans cesse croissante ... [more ▼]

Le système aquifère du horst de Diass situé à 50 km à l’Est de Dakar (Sénégal) est soumis à des pompages intensifs depuis plus de 50 ans pour assurer en continu une demande en eau sans cesse croissante destinée à l’Approvisionnement en Eau Potable (AEP) de la ville de Dakar et des localités de Sébikotane, Pout, Mbour ainsi que leurs besoins industriels et agricoles. La configuration géométrique du système est caractérisée par quatre failles majeures délimitant un horst où affleure la nappe du Maastrichtien gréso-calcaire et sablo-gréseux du compartiment de Diass encadrée par les compartiments calcaires affaissés de Sébikotane et de Pout qui hébergent la nappe captive à libre du Paléocène. L’exploitation de ce système a progressivement évoluée pour atteindre actuellement plus de 109000 m3/j environ avec cinq principaux centres de captage. Cette exploitation intensive a provoquée une baisse continue du niveau des nappes, un changement dans le régime des flux et une salinisation dans les zones de Sébikotane et de Mbour. Ainsi donc, il est nécessaire d’étudier les caractéristiques des aquifères notamment, leurs relations hydrauliques verticales et latérales. Cependant, cette étude reste difficile en raison de la complexité de la configuration géométrique du système et des pompages intensifs. La présente étude vise à contribuer à une meilleure compréhension du fonctionnement hydrodynamique du système pour une bonne gestion durable des ressources en eau. Plus précisément, il vise à déterminer : (1) le comportement spatio-temporel de l’hydrodynamisme et de l’hydrochimisme du système en rapport avec les pompages, (2) la recharge actuelle des eaux souterraines, (3) les zones potentielles de recharge nécessaires au calcul du bilan. Pour atteindre ces objectifs, une approche multidisciplinaire comportant une étude piézométrique, hydrogéochimique, d’estimation de la recharge spatialement distribuée et de modélisation a été utilisée. Les variations spatio-temporelles de la piézométrie depuis les années 1960 en rapport avec la configuration hydrogéologique combinées aux données chimiques et isotopiques ont été considérées pour fournir une meilleure compréhension du fonctionnement hydrodynamique du système et établir le modèle conceptuel de circulation des eaux. Les méthodes de Thornthwaite et Penman sont utilisées pour estimer la recharge qui a été spatialement distribuée sur les zones potentielles de recharge. Les enseignements clés tirés de ces différentes approches sont utilisés comme paramètre d’entrée du modèle hydrogéologique 3D développé et calibré en régime permanent et transitoire pour les périodes 1960-1971 et 1971-2009 respectivement. Les résultats montrent l’influence prépondérante des pompages sur le niveau piézométrique favorisant ainsi la drainance verticale et latérale vers les captages. Les données chimiques et isotopiques reflètent la dynamique du système. Les faibles teneurs en tritium et en 14C montrent une absence de recharge actuelle et une prédominance d’eaux anciennes dans le système. Cependant, la présence d’eau tritiée au droit de quelques forages indique un mélange avec des eaux récentes par drainance verticale descendante et/ou par écoulement latéral. Le fonctionnement hydrodynamique dérivé de ces résultats montre que le réservoir fonctionne comme un système aquifère multicouche avec des compartiments interconnectés par des failles qui favorisent des échanges de flux. L’aquifère du Quaternaire est alimentée par l’infiltration des eaux de pluie particulièrement dans la zone de Mbour (1) ; cette aquifère est drainé par les nappes profondes du Paléocène et du Maastrichtien (2) ; ce dernier draine le Paléocène (3), les écoulements latéraux se font du Maastrichtien de Diass vers le compartiment de Pout Sud et à partir du compartiment de Thiès vers le compartiment de Pout à travers les failles de Pout et de Thiès respectivement (4). [less ▲]

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See detailAdaptations structurales et fonctionnelles aux températures extrêmes au sein de la famille des alpha-amylases chlorure-dépendantes
Cipolla, Alexandre ULg

Doctoral thesis (2012)

L’adaptation thermique des protéines extremophiles a été étudiée de manière à approfondir notre compréhension des mécanismes moléculaires qui en sont responsables. Dans ce but, deux études ont été ... [more ▼]

L’adaptation thermique des protéines extremophiles a été étudiée de manière à approfondir notre compréhension des mécanismes moléculaires qui en sont responsables. Dans ce but, deux études ont été initiées et publiées. La première est basée sur la "mésophilisation" de l’α-amylase psychrophile AHA, issue de la bactérie Antarctique Pseudoalteromonas haloplanktis. L’ajout d’interactions faibles et d’un pont disulfure présents chez son homologue mésophile PPA de Sus scrofa et absents chez AHA ont permis de construire deux mutants multiples stabilisés, Mut5 et Mut5CC. Ces quatre enzymes ont été étudiées sur base de leur stabilité, de leur activité et de la perméabilité de leur structure protéique. L’étude des cinétiques de renaturation/dénaturation d’AHA, Mut5 et Mut5CC a permis de déterminer l’origine cinétique du gain de stabilité liée à l’ajout d’interactions faibles et du pont disulfure chez AHA. Il en résulte que Mut5 et Mut5CC ont effectivement été stabilisés mais en contrepartie ils ont perdu l’optimalisation de l’activité à basse température observée chez AHA. De plus, la perméabilité de leur structure protéique s’est réduite, se rapprochant de celle de PPA. L’origine du gain de stabilité est liée à une diminution des cinétiques de dépliement sans modification des cinétiques de repliement. Non seulement ces résultats démontrent l’importance du rôle des interactions faibles dans l’adaptation thermique des protéines mais de plus, ils démontrent la synergie entre celles-ci. La seconde étude a pu être développée par la découverte d’une α-amylase chlorure-dépendante thermophile TFA issue de l’actinomycète Thermobifida fusca et par la production de l’α-amylase chlorure-dépendante mésophile ectotherme DMA de Drosophila melanogaster. Ainsi avec AHA et PPA respectivement comme représentants psychrophile et mésophile homéotherme, nous pouvions couvrir l’ensemble des températures physiologiques/environnementales connues. Nous avons pu mettre en évidence le continuum des propriétés physico-chimiques observées (activité, stabilité, affinité pour le substrat…) mais aussi que l’énergie thermique de l’environnement influence grandement l’activité enzymatique qui ne serait pas contrebalancée par les mécanismes adaptatifs. L’influence de la température sur l’activité a mis en évidence la plus faible dépendance d’AHA par rapport à TFA. Ces travaux ont permis d’améliorer notre compréhension des mécanismes moléculaires liés à l’adaptation thermique des protéines et du rôle joué par les interactions faibles dans cette adaptation. Ils ouvrent aussi la voie à de futures recherches visant à analyser par d’autres méthodes la flexibilité de la structure protéique et à cristalliser TFA pour étudier d’un point de vue structural le continuum des propriétés physico-chimiques mis en évidence au cours de ce travail. [less ▲]

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See detailPresent and future Greenland ice sheet surface energy balances with the help of the regional climate MAR model
Franco, Bruno ULg

Doctoral thesis (2012)

See enclosed abstract-and-contents.pdf

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See detailStructure and Lattice Dynamics of Thermoelectric Complex Chalcogenides
Bauer Pereira, Paula Beatriz Lee ULg

Doctoral thesis (2012)

The goal of this work is to characterize the structure and lattice dynamics of complex chalcogenide alloys. Particular interest is paid to the system AgPbmSbTem+2 (LAST-m), AgSbTe2 and the binaries PbTe ... [more ▼]

The goal of this work is to characterize the structure and lattice dynamics of complex chalcogenide alloys. Particular interest is paid to the system AgPbmSbTem+2 (LAST-m), AgSbTe2 and the binaries PbTe, SnTe and GeTe. Synchrotron radiation studies including high energy X-ray di raction and nuclear inelastic scattering, and macroscopic measurements of heat capacity and elastic constants were performed. A new resonant ultrasound spectroscopy setup with capable of performing measurements from room temperature to 1073K was built for mechanical characterization of the thermoelectric alloys at their working temperatures. The rst chapter presents a brief review of relevant information on thermoelectricity and on the materials under study. The characterization methods including heat capacity, resonant ultrasound spectroscopy, X-ray di raction and nuclear inelastic scattering are introduced. Not as an exhaustive review, but rather in order to give the reader a basic level of understanding and a sense of the acessible information. The introduction is followed by three chapters which address the experimental studies of lattice dynamics in chalcogenide alloys. Chapter 2 describes the lattice dynamics in the compounds GeTe, SnTe and PbTe studied by 119Sn and 125Te nuclear inelastic scattering. The obtained partial density of phonon states were compared with published theoretical calculations, and the resulting vibrational properties were found to be in good agreement with these reports. Additionally, the phase purity and structure were characterized by high energy X-ray di raction. The atomic arrangement, rhombohedral for GeTe and cubic for SnTe and PbTe, is seem to a ect the density of phonon states, with the NaCl-type structure having a softer character in comparison with the rhombohedral structure. In Chapter 3, the lattice dynamics of a polycrystalline AgSbTe2 sample was investigated by 121Sb and 125Te nuclear inelastic scattering, at low temperatures. For this compound, the phonon modes have energies below 25meV and a sound velocity of vs =1490(30) m/s was determined. A simple temperature independent estimation of the lattice thermal conductivity of AgSbTe2 yielded L =0.50 0.05Wm􀀀1K􀀀1. The low Debye temperature, D =150(15)K combined with the short phonon lifetime and the low sound velocity are found to be key factors for the low thermal conductivity in AgSbTe2 and are related to the good thermoelectric performance in AgSbTe2 and AgSbTe2containing systems. Chapter 4 is dedicated to the study of the average and local structure in bulk AgPb18SbTe20 alloy, by a combined Rietveld and Pair Distribution Function analysis. The strong in uence of the synthesis conditions on the lattice parameters and on the composition and the concentration of nanoclusters in LAST-18 is con- rmed. Moreover, the 121Sb and 125Te partial density of phonons states were obtained by nuclear inelastic scattering in order to separately characterize the lattice dynamics from the matrix and the nanoinclusions. Additional characterization of the elastic properties and lattice governed properties were performed by resonance ultrasound spectroscopy, heat capacity and thermal expansion measurements. The nal chapter is dedicated to the resonant ultrasound spectroscopy technique, and the process of building up this bu er-rods high-temperature measurement system are presented. Advantages and disadvantages, as well as limitations and di culties are discussed. Using the \mode-tracking" method, the mechanical behavior of a PbTe and a Niobium sample, from room temperature to 523K and from room temperature to 973 K, respectively, were investigated. [less ▲]

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See detailA multiaxial constitutive model for concrete in the fire situation including transient creep and cooling down phases
Gernay, Thomas ULg

Doctoral thesis (2012)

Purpose - The present thesis aims to develop an efficient and reliable multiaxial concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. The need ... [more ▼]

Purpose - The present thesis aims to develop an efficient and reliable multiaxial concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. The need for proper concrete model remains a very challenging task in structural (fire) engineering because of the complexity of the concrete mechanical behavior characterization and the severe requirements for the material models raised by the development of performance-based design. Methodology - The thesis opted for a phenomenological approach for modeling the thermo-mechanical behavior of concrete. The specifications of the model are based on the study of published experimental data of concrete samples tests and on the specific needs related to the applications in structural fire engineering. With these specifications in mind, a state of the art review of concrete models is conducted in order to choose the general theoretical framework that best fits the criteria for the development of the new model. The thesis presents the theoretical development of the model and its numerical implementation in a finite elements software. Numerical simulations of experimental tests are then performed to verify that the model satisfy the specifications. Findings - The combination of elastoplasticity theory and damage theory allows to develop a phenomenological model suitable for concrete behavior modeling within the pragmatic and robust theoretical framework of continuum constitutive models based on smeared crack approach. The state of damage in concrete, assumed isotropic, is modeled by means of a fourth order damage tensor to capture the unilateral effect. When complex performance-based situations are considered, the effect of transient creep strain at high temperature must be taken into account by an explicit term in the strain decomposition. A generic transient creep model is therefore developed based on experimental data and the model is calibrated to yield the same results as the Eurocode implicit model in simple prescriptive situations. The concrete model comprises a limited number of parameters that can be identified by three simple tests; besides, a standard set of values to be used in predictive calculations is clearly defined for these parameters. Numerical simulations can deal with all stress states as the model is developed as fully three-dimensional. A large number of examples highlight the capabilities of the model that range from the modeling of sample tests to the modeling of large scale composite structures developing membrane action. Limitations – Due to the assumption that damage and plasticity are driven by the same internal variables in the model, a limitation appears for capturing the concrete post-peak behavior in highly confined stress states. This assumption allows for reducing the number of parameter but it restrains the domain of applicability of the model; it is suggested to adopt a different approach if the behavior in multiaxial compression at high confinement level has to be accurately captured. Another limitation of the model is related to the localization issue, which is only partly addressed in this work by means of the regularization of the crack energy. Further works should bring a more elaborated response while considering the case of reinforced concrete structures, in which numerous cracks develop. Finally, several simplifying assumptions have been adopted to restrain the scope of the research; for instance, the phenomenon of spalling has not been considered. Practical implications - The thesis includes implications for the development of advanced numerical tools for the simulation of concrete structures at ambient temperature and at high temperature. The use of such advanced tools in the design may lead to significant reduction in the building costs and to improved robustness of the structures. Value – The thesis contributes to fulfil an identified need to make available proper constitutive concrete model for implementation in finite elements softwares dedicated to the analysis of structures in fire. Special care is given to the numerical robustness of the model and to the clear definition of the material parameters as the model is intended to be used by structural (fire) engineers in real applications. [less ▲]

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See detailThe Unharnessed World: Janet Frame and Buddhist Thought
Gabrielle, Cindy ULg

Doctoral thesis (2012)

Though New Zealand author Janet Frame (1924-2004) lived at a time of growing dissatisfaction with purely Western (i.e. European) cultural models, her work has so far never been examined from the vantage ... [more ▼]

Though New Zealand author Janet Frame (1924-2004) lived at a time of growing dissatisfaction with purely Western (i.e. European) cultural models, her work has so far never been examined from the vantage point of its indebtedness to Eastern epistemologies, and to Buddhism in particular. Even though it is possible to establish links between an author and a given system of thought (Heidegger’s for instance) without necessarily buttressing the comparison from a factual perspective, in this case, the author’s (auto-)biography, her fiction and letters, as well as the circles of Buddhists or Buddhist-sympathizers in which she evolved at a given time, all testify to the fact that a direct encounter between Janet Frame and Buddhism did occur. It can thus be affirmed that, just like W.B. Yeats, C.G. Jung, Heidegger and many others before her, one of the most striking personalities of the 20th century was drawn eastward. The relevance of this study to Janet Frame scholarship resides not only in its politicized angle of approach but also, more importantly, in the fresh light it sheds on entire segments of the Framean corpus which have tended to remain obdurately mysterious; this includes passages centering on e.g. the existence of a non-dual world, a reality un-harnessed by the partial categories of empirical thinking, on a character’s sudden embrace of a non-ego-like self, or on the jolting back of distracted individuals into an awareness of their physical reality in ‘this’ profane world. On the whole, and despite this apparent profusion of themes, my concern is to show that these obscure passages, as well as many other key moments in the narratives, all coalesce into a systematic deconstruction of empirical thinking and its point of anchorage in a discriminating kind of consciousness, both notions forming excellent points of entry into virtually all the texts produced by Frame. Through a careful mapping of the impact of discriminating habits of thought on the self’s place of being in the world and perception thereof, this work clarifies, or rather reconstructs, the narratological architecture of the studied texts – especially the novels – quite apart from the somewhat restrictive view, held in some circles of literary criticism, that they are mazes of random turnabouts and dead-ends where narrotological playfulness is valorized for its own sake. To provide just one example of how a study of Janet Frame via Buddhist thought facilitates the navigation of the author’s intricate novels, the idea in Buddhism that the artist is the bow that shoots the arrows, but then s/he is the target also, is a useful starting point for analyzing the seminal “Jan Godrey” (one of Frame’s best known short stories) in which a terrified author-figure finally allows her creature of words, described as an alien inside, to take full control of the speaking position. A contrario, Thora Pattern’s willingness in The Edge of the Alphabet to trap her creation within neat academic cages of words (as she calls them) spawns images of a hellish self-scape of containment which translate in an endless regression of framed frames since her attitude is paralleled by some of her own creatures of words and by the Christian God Himself – each at his or her level of being and of influence. But that is not all for, in a last turn of the screw, and pace the critics who diminish their roles in the narrative, Thora’s characters rebel against their creator, and they succeed in jamming her creative incarcerating mechanisms so that, by the end of the novel, the author-figure is no longer able to exist without the not-self. This dialectics of un/framing, in which a discriminating consciousness battles against the invading otherness of the non-dual, unharnessed world in all its manifestations, is one which typically informs the Framean corpus although, of course, the architecture of enactments it gives birth to is as varied as it is unpredictable. The idea, which Frame shares with Buddhism or with Nietzsche (who, incidentally, owes an intellectual debt to Buddhism), that most of the human existence is characterized by the “will to power,” i.e. by the drive to take full possession of one’s chosen place of being, is rather unflattering for her fellow human beings. In another sense, the author’s conception of our (in-)humanity as being made up of an accretion of egotistic habits that can be unlearned certainly explains why, in her oeuvre, a liberation from totalizing structures demands an encounter with the negative of place, of identity, of vision, of sound, of fullness, of shape, of well-worn mind-routes and, as we saw in the last chapter, with the negation of negation. Often, it takes no less than a rebellion of the supposedly harnessed reality to disorient a protagonist’s dualistic bearings or to jam an artist’s incarcerating mechanisms; and this, in part, accounts for the extreme physicality encoded in a fiction replete with moments of thumping or bashing – indeed with the promise of a cut finger. Still pondering the centrality of ‘unframed’ or ‘ego-less’ modes of being, each of the nine chapters that constitute this work aims at countering the oft-recurring claim that Frame’s oeuvre is studded with traces of a ‘beyond’ which no character can ever approach because ‘one cannot explore beyond’. By this definition, each of the questing selves that clutters the author’s haunting universe is condemned to failure beforehand, as it were, while concomitantly the Framean text itself is deemed to be bleak, defeatist, even nihilistic. Therefore, it is of the utmost significance that a Buddhist navigation of Frame’s texts should lead one to the conclusion that this unharnessed world which human beings are often unable to apprehend and embrace has always been right under their nose so that, between ‘this’ world of limited perceptions and ‘that’ world of the beyond, the boundary is as thick or as thin as the walls of a self-made conceptual prison. Indeed, whenever the aspect of the intellect that filters perceptions into mutually excluding categories fails to function, or is willingly jettisoned by a protagonist, s/he finds a place of subjective arrival in, and sees, this supposedly unknowable ‘beyond’. Thus, possibly against the grain of mainstream criticism, this study argues that Janet Frame constantly seeks ways through which the infinite and the Other can be approached, though not corrupted, by the perceiving self, and that she found in the Buddhist epistemology a pathway towards grasping such alterity. [less ▲]

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See detailSubstrats cérébraux des processus moteurs automatiques et inconscients
D'Ostilio, Kevin ULg

Doctoral thesis (2012)

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See detailLe terrorisme à motif religieux en Turquie : Recrutement, profils et motivations des membres du Hizbullah turc
Gülver, Murat ULg

Doctoral thesis (2012)

Depuis plus de cinquante ans, la Turquie a été la victime permanente d’actes terroristes aux multiples motivations. Ces dernières années, le terrorisme à motif religieux y a connu une montée en puissance ... [more ▼]

Depuis plus de cinquante ans, la Turquie a été la victime permanente d’actes terroristes aux multiples motivations. Ces dernières années, le terrorisme à motif religieux y a connu une montée en puissance. Plus de dix organisations terroristes, se basant sur une idéologie religieuse, ce sont organisées sur le territoire turc dans le but de changer le système politique et pour fonder un État islamique. Dans cette recherche, nous avons examiné le cas du Hizbullah turc, en tant que la plus grande et la plus violente organisation terroriste à motif religieux en Turquie. Cette étude a exploré d’abord les méthodes de recrutement du Hizbullah, ensuite les profils de ses militants et enfin les motivations individuelles et les facteurs, qui se trouvent à la base de la radicalisation religieuse en Turquie. Pour ce faire, l’examen quantitatif et qualitatif de données originales comble les principales lacunes dans la recherche sur le terrorisme à motif religieux et donne des indications pour de futures recherches criminologiques et de politiques de sécurité préventives. Dans cette étude, pour examiner et comprendre le recrutement, les profils et les motivations des membres du Hizbullah, nous avons utilisé essentiellement deux sources : les autobiographies des militants eux-mêmes et les entretiens semi-structurés avec des policiers spécialistes du terrorisme à motif religieuse, ainsi que des desservants du culte islamique, qui ont une expérience dans les régions où le Hizbullah était actif. Cette recherche entend apporter une contribution significative à la compréhension des motivations individuelles des militants du Hizbullah, à l’identification des caractéristiques des membres, et à la définition des méthodes de recrutement de l’organisation. Elle propose en outre de nombreuses informations aux organisations de sécurité pour la lutte antiterroriste. [less ▲]

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See detailLa protéine JNKBP1 agit comme un régulateur négatif de la signalisation de NOD2 en inhibant son processus d’oligomérisation
Lecat, Aurore ULg

Doctoral thesis (2012)

Le récepteur cytoplasmique NOD2 est l'un des membres les mieux caractérisés de la famille des NLRs. NOD2 est capable de détecter le muramyldipeptide (MDP), un composant de la paroi bactérienne, ce qui ... [more ▼]

Le récepteur cytoplasmique NOD2 est l'un des membres les mieux caractérisés de la famille des NLRs. NOD2 est capable de détecter le muramyldipeptide (MDP), un composant de la paroi bactérienne, ce qui induit les différentes cascades de signalisation conduisant à l'activation de NF-κB, des MAPKs et de l'autophagie. Ces voies contribuent à une réponse immunitaire innée et adaptative efficace. La perte de fonction des mutants NOD2 a été associée à une plus grande susceptibilité à la maladie de Crohn, ce qui souligne l'importance physiologique de la régulation de l'activité de NOD2. Nous avons effectué une étude par une approche protéomique pour rechercher de nouveaux régulateurs de NOD2. Nous avons généré un modèle cellulaire pour cette étude, les cellules HEK293GNV. Nous avons identifié plusieurs nouveaux partenaires de NOD2, dont la protéine JNKBP1 (c-Jun N-terminal kinase binding protein 1), une protéine scaffold caractérisée par un domaine WD40 en amino-terminal. Nous avons aussi débuté la caractérisation d’autres protéines appartenant aux complexes NOD2 purifiés comme ROCK2 (Rho activated kinase 2) et HDAC5 (Histone deacetylase 5). Au vu de nos premiers résultats, les protéines ROCKs sembleraient être des activateurs de la voie NOD2. Nous nous sommes principalement consacrés à l’étude de JNKBP1 qui a été identifiée, en 1999, comme un partenaire et un régulateur positif de JNK. Nous avons montré que JNKBP1 via son domaine WD40, se lie à NOD2 suite à l’activation par le MDP. Cette interaction atténuait l'activation de NF-κB dépendante de NOD2, la synthèse de l'IL-8 et l’activité antibactérienne de NOD2. JNKBP1 exerçait son effet répresseur en perturbant l’oligomérisation NOD2 et la phosphorylation de la tyrosine de RIP2 : deux étapes nécessaires à la signalisation en aval. En outre, nous avons montré que JNKBP1 et NOD2 étaient exprimées dans l'épithélium intestinal humain et dans les cellules immunitaires recrutées dans la lamina propria, ce qui suggère que JNKBP1 contribuerait au maintien de l'homéostasie intestinale dépendante de NOD2. [less ▲]

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See detailStructure and Lattice Dynamics of Bismuth Telluride Nanostructures
Bessas, Dimitrios ULg

Doctoral thesis (2012)

A brief outline of experimental lattice dynamics related to thermal transport in solids introduces this thesis. The introduction is followed by three chapters dedicated to structure and lattice dynamics ... [more ▼]

A brief outline of experimental lattice dynamics related to thermal transport in solids introduces this thesis. The introduction is followed by three chapters dedicated to structure and lattice dynamics of bulk and nanostructured bismuth telluride, a chapter on lattice instabilities observed in bulk EuTiO3 around room temperature, and a chapter on the development of a resonant ultrasound spectrometer for small samples. First, the lattice dynamics in bulk Bi2Te3 and Sb2Te3 were investigated by nuclear inelastic scattering, diffraction of high energy synchrotron radiation and calorimetry. In combination with earlier inelastic neutron scattering data, the element specific density of phonon states was extracted not only for Te and Sb but also for Bi. The Bi-Te bonding in Bi2Te3 is fundamentally different than the Sb-Te bonding in Sb2Te3. It appears that the Te specific density of phonon states is mostly unaffected upon substitution of Sb with Bi. Phonon polarization analysis was conducted in a Bi2Te3 single crystal. The observed low lattice thermal conductivity in bulk Bi2Te3 and Sb2Te3 results essentially from the small acoustic cut off energy. Second, the lattice dynamics in elemental modulated Sb2Te3 films were studied by nuclear inelastic scattering and diffraction of high energy synchrotron radiation. These studies reveal that the main features in the Sb specific density of phonon states arise from the layered structure. The extracted average speed of sound is practically the same as in bulk Sb2Te3. The impact of the acoustic cut off energy is further highlighted. Third, the phonon confinement in a Bi2Te3 nanowire array was studied by nuclear inelastic scattering, diffraction of high energy synchrotron radiation, scanning as well as transmission electron microscopy. For the first time the element specific density of phonon states was measured on nanowires in two perpendicular orientations. The much lower than in bulk average speed of sound measured in 56 nm diameter nanowires is directly related to the confined dimensions. The related 50 % decrease in macroscopic thermal conductivity is in line with macroscopic measurements on similar nanowires. Fourth, a detailed structural and lattice dynamical investigations of the bulk cubic perovskite EuTiO3 revealed a lattice instability close to room temperature. The low temperature phase is associated with anharmonic europium displacement and has a significant impact in the lattice dynamics. Last, a resonant ultrasound spectrometer for measurements on small samples and thin films was developed. Successful measurements versus temperature of the elastic constants were carried out with sub-percentage accuracy on oriented single crystals smaller than 1 mm3. [less ▲]

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