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See detailCharacterization, dynamics and trophic ecology of macrofauna associated to seagrass macrophytodetritus accumulations (Calvi Bay, Mediterranean Sea)
Remy, François ULg

Doctoral thesis (2016)

Posidonia oceanica meadows are a major coastal Mediterranean ecosystem. Although highly productive this Mediterranean marine flower plant is not much consumed by herbivore organisms. During autumnal ... [more ▼]

Posidonia oceanica meadows are a major coastal Mediterranean ecosystem. Although highly productive this Mediterranean marine flower plant is not much consumed by herbivore organisms. During autumnal senescence, most (up to 90%) of the foliar primary production of P. oceanica ends in the “detrital compartment”. These dead leaves, also called “macrophytodetritus”, begin to degrade immediately inside the meadow, but a large amount will be rapidly exported to adjacent unvegetated accumulation zones, such as bare sand patches. Associated to drift macroalgae, living detached P. oceanica shoots, micro-organisms and fine sediment, these macrophytoderitus form what we call “exported P. oceanica litter”. This exported litter is a highly dynamic habitat for a whole community of invertebrates: meiofauna (38µm < size < 500µm) and macrofauna (size ≥ 500µm) on which we focused on. This dynamic nature of exported litter could play a major structuring role in terms of abundance, diversity and trophic ecology of this vagile macrofauna community at a seasonal, annual or spatial scale, but also during stochastic, brief and very strong perturbations: resource pulses. In this context, this PhD Thesis had 7 main objectives: i. Characterize for the first time exhaustively the macrofauna community. ii. Evaluate the spatiotemporal changes occurring at two different time scales in the detritus themselves and in the macrofauna community. iii. Relating these variations with measured environmental parameters. iv. Experimentally demonstrate the stratification occurring in a stable P. oceanica litter accumulation and the impact of this stratification on environmental conditions and on the macrofauna. v. Experimentally demonstrate the impact of resource pulses on the exported P. oceanica litter macrofauna community. vi. Unravel for the first time the global P. oceanica litter macrofauna food web using gut contents examinations and stable isotopes (C and N). vii. Evaluate the spatiotemporal changes of diet preferences of this community and determine if the observed changes are really synonym of true diet changes. This PhD Thesis demonstrated that exported P. oceanica litter was mainly composed of dead P. oceanica leaves (70-80%). It followed the natural annual cycle of P. oceanica and presented a maximum abundance in autumn just after leaves senescence. Measured environmental parameters also showed important variations linked to different factors such as force and direction of the wind, litter abundance and probably temperature. The continuous presence of the vagile macrofauna community throughout the year was demonstrated as well. This community was composed of 115 species and largely dominated by arthropods (77%), followed by annelids (12%) and mollusks (7%), while other taxa were much more anecdotal. Even if diversity is quite important, only a few species dominate largely the community. Indeed, 19 species represent more than 90% of the total abundance. One species to keep in mind: Gammarella fucicola, the most typical dominant and abundant amphipod species, representing 40-50% of the total abundance. In addition to this general pattern, litter vagile macrofauna presented important seasonal and annual variations. In the case of several species, these variations could be linked to some measured environmental parameters, but we had to recognize that most species did not seem to be influenced by environmental parameters measured during this PhD. However, oxygen concentration was the most important environmental parameter, potentially influencing 7 of the 19 most dominant and abundant species. The experimentally demonstrated physico-chemical stratification occurring inside litter accumulations was strongly related to this oxygen parameter. Indeed we demonstrated that several species were distributed in the different layers of a litter accumulation according to oxygen concentration and to a lesser extent, to nutrients concentration (mostly NH4). Besides, smaller time scale sampling allowed the identification of several stormy events corresponding to the definition of resource pulses. These pulses were demonstrated to play a potentially important role on the structure of the macrofauna community, favoring importantly the detritivore species and hypoxia tolerant species. It was also demonstrated that resource pulses could induce diet switching increasing the consumption of dead P. oceanica leaves just after the events, potentially increasing the litter decomposition by the macrofauna. The trophic web described in this PhD Thesis was composed of several trophic levels, from the primary herbivore/detritivore consumer, to second order carnivore predators. Different dietary preferences were highlighted, but major information was that dead P. oceanica leaves were ingested by a majority (85%) of the sampled species. Moreover, stable isotope analysis confirmed that P. oceanica litter was assimilated by most primary consumers and this “detrital signal” could be identified to the upper trophic levels, which is an argument in favor of the importance of macrofauna as major dead P. oceanica leaves decomposers. This also highlighted their potential role in terms of organic matter transfer from the P. oceanica meadow itself to the Mediterranean coastal food webs. Seasonal variations were observed in terms of trophic niches, and SIAR mixing model confirmed that this variability was sometimes caused by real diet modifications, potentially linked to the variable availability of food sources. This PhD Thesis, combining standardized sampling at two different time scales, trophic web analysis (gut contents and stable isotopes) and original experimentation allowed us to describe a diverse and abundant macrofauna community associated to P. oceanica exported litter, its temporal variations, potential responses to resource pulses as well as the link existing between some species and measured environmental parameters. This PhD also described the food web of this community and demonstrated the importance of dead P. oceanica leaves as food source for many invertebrates composing this community. These invertebrates thus seemed to play an important role in both litter decomposition and organic matter flux from the P. oceanica meadow to the Mediterranean coastal food webs. [less ▲]

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See detailSolid-supported synthesis of peptidoglycan fragments and their biological evaluation
Simon, Justine ULg

Doctoral thesis (2016)

In this work, a new methodology for the synthesis of peptidoglycan fragments containing (2S,6R)-A2pm is proposed. Thanks to a solid phase platform, cross metathesis was achieved between two easily ... [more ▼]

In this work, a new methodology for the synthesis of peptidoglycan fragments containing (2S,6R)-A2pm is proposed. Thanks to a solid phase platform, cross metathesis was achieved between two easily manufactured chiral synthons, allylglycine anchored to a resin and vinylglycine derivatives. Due to the need of fragments for the study of the peptidoglycan recycling, this modular efficient platform could be useful to synthesize diverse derivatives of other peptides and muropeptides containing (2S,6R)-A2pm. In the framework of this project, (S)-Ala-γ-(R)-Glu-(2S,6R)-A2pm-(R)-Ala and γ-(R)-Glu-(2S,6R)-A2pm were synthesized. Their interactions with the R39 peptidase were studied by X-ray diffraction. According to the crystallographic results, (S)-Ala-γ-(R)-Glu-(2S,6R)-A2pm-(R)-Ala 1 is a reversible covalent binding inhibitor of R39. These data are supported by an enzymatic study using the thioesterase activity of the R39 peptidase on (R)-S2d. Because of the specific affinity for the R enantiomer of thioesters, the enantioselective synthesis of (R)-S2d is described that makes use of the coupling agent T3P. A chromatographic method is proposed to evaluate the degree of thioester racemization. The kinetics of the interaction between the thioester and different PBPs were studied and a protocol for microtiter plate-based assays is developed allowing the screening of compound libraries for inhibitors of PBPs. In the future, the synthesized peptidoglycan fragments will be used as reference compounds in the framework of the NetRBI project. [less ▲]

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See detailLe passé en France au XVIIe siècle. Représentations, usages et transferts des savoirs historiques
Saal, Caroline ULg

Doctoral thesis (2016)

La majeure partie des études sur le passé au XVIIe siècle se porte sur l’historiographie, sur la théorie de l’histoire et sur son écriture à cette époque. Grâce au développement de l’histoire des idées et ... [more ▼]

La majeure partie des études sur le passé au XVIIe siècle se porte sur l’historiographie, sur la théorie de l’histoire et sur son écriture à cette époque. Grâce au développement de l’histoire des idées et de l’histoire culturelle, de nouvelles approches ont émergé. Pour l’histoire moderne française, elles prennent essentiellement la forme d’études de figures souvenirs et de leur prégnance dans une culture donnée. Mais deux postulats m’ont invitée à travailler autrement, hors des pratiques historiennes et sans choisir a priori de figures-souvenirs. Le premier tient à l’acquisition des savoirs historiques. La connaissance que possède une personne sur le passé de la communauté humaine résulte d’une multitude de vecteurs et de médias, de nature et d’objectifs divers, et, plus encore, elle résulte de leur croisement. Le second postulat provient des innovations en histoire des savoirs de ces dernières années : une société ancienne repose sur un système de pensée et sur une configuration des savoirs distincte de la nôtre. Pour travailler sur les savoirs sous l’Ancien Régime, il faut appréhender l’altérité d’un ancien régime des savoirs et, plutôt que de rechercher la généalogie de disciplines, regarder à l’œuvre ces savoirs mixtes, aux nombreuses ramifications, la manière de les créer, de se les approprier et de les utiliser. Certes, Reinhart Koselleck et Kristof Pomian avaient déjà produit d’importants enseignements sur les processus. On a longtemps considéré qu’ils avaient probablement tout dit. Il fallait pourtant vérifier la percolation de ces enseignements au-delà des génies créateurs et des penseurs institués. Cette thèse étudie ces processus dans des opérations d’appropriation des savoirs historiques au sein des publics alphabétisés et la compréhension de ces savoirs en société : les pamphlets « historiés » de la Fronde, les conférences du Bureau d’Adresse de Théophraste Renaudot et des estampes ludiques – jeux de carte et jeux de l’oie historiques. Elle démontre le rôle de ces imprimés de forme brève comme lieux d’acculturation des savoirs historiques, mettant à disposition un prêt-à-penser sur le passé. S’inspirant des grilles de lecture des théories de la pensée complexe, développée entre autres par Edgar Morin, elle éclaire la pluralité des questions que se posaient les hommes de l’époque moderne sur leur passé, et les liens entre ces questions, leur lieu social d’émergence, les pratiques de la connaissance et les paradigmes culturels. [less ▲]

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See detailOn Vulnerability and Vulnerabilities of Incident Reporting
Rossignol, Nicolas ULg

Doctoral thesis (2016)

This PhD thesis – composed of a series of five papers tied together by an introduction and conclusions – explores the functioning of an Incident Reporting System used in a high-risk organization. It aims ... [more ▼]

This PhD thesis – composed of a series of five papers tied together by an introduction and conclusions – explores the functioning of an Incident Reporting System used in a high-risk organization. It aims at understanding how safety is actually constructed by and through this reporting system and what it actually does to the meaning of safety when it prescribes a set of sociotechnical practices. From a conceptual point of view, this PhD thesis departs from classical risk or vulnerability analyses which tend to measure factors in order to produce what are supposed to be “objective” results and “manageable” recommendations for decision makers. By relying on a constructivist understanding of vulnerability, this research explores and characterizes situations and events the consequences of which are ambiguous and the probabilities of which are uncertain. It thus broadens the scope of classical risk or vulnerability analyses and complements it with a qualitative and discourse-based attention to organizational, cultural and ethical questions. [less ▲]

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See detailSexual attraction in lady beetles: fundamentals and applications
Fassotte, Bérénice ULg

Doctoral thesis (2016)

Sustainable agriculture relies on the development of environmentally friendly methods of crop production. Therefore, alternative solutions are required to decrease insecticide use and to promote the ... [more ▼]

Sustainable agriculture relies on the development of environmentally friendly methods of crop production. Therefore, alternative solutions are required to decrease insecticide use and to promote the efficacy of natural enemies against insect pests. Investigating the sexual behavior of lady beetles is of practical relevance, because these insects could be used to reduce plant-feeding insect populations in crop fields by taking advantage of their predatory behavior. In this context, the objective of this PhD thesis was twofold: (1) a fundamental research that focuses on the identification of the sex pheromone of Harmonia axyridis (Pallas) and (2) an applied approach aimed at elaborating semiochemicals slow-release dispensers with these compounds, in order to attract individuals in cultivated fields. We have demonstrated that virgin females of H. axyridis display a typical male-calling behavior in presence of prey, which is associated with the release of a pheromonal blend that is highly attractive for conspecific males. Dynamic headspace sampling and subsequent chemical analyses allowed the characterization of this sex pheromone. Finally, we focused on the development of a formulation releasing a combination of semiochemicals that attract aphid predators. The formulation, composed of alginate beads, was optimized under laboratory conditions. The release rate of the formulation was assessed by dynamic headspace sampling coupled with adsorbent trapping. The formulation was efficient at attracting two natural enemies of aphids. All these results are discussed in the context of sustainable agriculture, with the use of semiochemicals, and especially pheromones, as potential tools to enhance current cropping systems. In near future, the application of such molecules, based on strong knowledge of insect olfaction, is expected to increase considerably with the development of new methods aimed at attracting predators and/or parasitoids. In addition, improvements of experimental devices, such as the elaboration of slow release dispensers, are suggested in the last chapter of this PhD thesis. [less ▲]

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See detailLe billonnage cloisonné en agriculture des montagnes: évaluation et facteurs d'acceptation. Cas des Hauts Plateaux de l'Ouest-Cameroun
Djoukeng, Henri Grisseur ULg

Doctoral thesis (2016)

In the Western Highlands of Cameroon as in all other regions of the world where mountain agriculture is practiced, erosion and runoff pose a real threat to the sustainable preservation of natural ... [more ▼]

In the Western Highlands of Cameroon as in all other regions of the world where mountain agriculture is practiced, erosion and runoff pose a real threat to the sustainable preservation of natural resources. Generally, plots located on the slopes of the mountains in the Western Highlands have either become less productive or totally unproductive; this situation is exasperated by the scarcity of arable land which is largely attributed to cultural practices that do not take into account soil and water conservation methods. To better quantify the impacts of erosion and runoff on the different functions assigned to agriculture and agricultural holdings, this thesis has implemented tied ridging which is an unused soil and water conservation technique. We have thus compared the effectiveness of the existing soil preparation methods (ridging along the steepest slopes and flatbed cultivation) with tied ridging on two operating slopes namely 11% and 29%. The results showed a significant difference between the current practice (flatbed and ridging along the steepest slopes) and tied ridging in terms of soil loss (p = 0.003), yields (p = 0.003), and runoff water (p < 0.001). Under sole cropping of potato on a hectare of land, the tied ridging led to: (i) increase in populations of cultivated plants by 7%, (ii) significant reduction of runoff (lowered by a factor of seven) and soil loss (lowered by a factor of five), (iii) increase in yields by 80%, (iv) increase in farmer’s profitability by approximately 908388 FCFA.ha-1. The tied ridging needed 41% extra work regardless the slope of the land on which it was practiced. The tied ridging showed undeniable advantages: the stress of additional work was offset by the gain in yields for producer; additional work created additional job opportunities for the community; and tied ridging improved the conservation of soil and water for a healthy environment. Although the technique has several advantages, the provision of financial means for its implementation could be a negative point, because family labor supply is generally insufficient for its realization and the hired labor is expensive. Further work was dedicated to measuring the rate of adoption of the tied ridging technique and analysis of the determinants for adoption. The study showed that exploiting land ownership by farmers is a key factor in the implementation of soil conservation techniques. The results showed tied ridging adoption rates of 93% and 62% for dignitaries and other farmers respectively. Overall, access to land, operating slopes, and adoption of soil and water conservation techniques were significantly influenced by agronomic potentials of plots and socio-economic situation of farmers (p <0.05). Finally, in order to quantify the overall impact of tied ridging on the quality of surface water, we measured the proportion of sediments migrating from plots under the three soil preparation methods and entering to the river’s bed. The collected and measured sediments consisted of soil, plant residues, and other wastes (chemical packages, plastic casing used for irrigation, and food packages). The results showed that tied ridging cultivation method significantly reduced siltation of the Méloh River (p<0.05). Compared to 2012 and 2013, quantities of sediment decreased by 66% in 2014, the year in which the tied ridging technique was adopted on 75% of the plots. Thus the flatbed and ridging along the steepest slopes soil preparation methods are the principal cause of siltation and pollution of the Méloh River. The results of this research led to the following prospective approaches for improvement: (i) test the tied ridging technique with other crops and with different inter mounds’ spacing, (ii) study the facilitation of access to credit and creating farmer's organizations for promoting the adoption of tied ridging, (iii) test other soil and water conservation techniques such as live hedges, direct-sowing mulch-based crop (agroecology), and agroforestry, and (iv) conduct general limnologic studies of watersheds. The general limnology studies the surface waters according to their seasonal variations, and their physico-chemical and biological aspects. [less ▲]

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See detailSTUDY AND CHARACTERIZATION OF MAGNETIC AND MULTIFERROIC MATERIALS BY FIRST-PRINCIPLES CALCULATIONS
Garcia Castro, Andrés Camilo ULg

Doctoral thesis (2016)

In the last fifteen years, multifunctional materials, and more specifically, multi- functional oxides have been widely studied due to its wide range of properties. Properties that go from ... [more ▼]

In the last fifteen years, multifunctional materials, and more specifically, multi- functional oxides have been widely studied due to its wide range of properties. Properties that go from superconductivity to ferroelectricity passing through mag- netism and multiferroism have been reported. Nonetheless, the fluoride family was left aside and little information is known about its possible ferroelectricity or mul- tiferroism. In this Ph.D thesis, we explored the electronic, vibrational, structural and magnetic properties of fluoride perovskite-based compounds. To such pur- poses, We performed ab-initio calculations based in the density-functional theory (DFT) as implemented in VASP and CRYSTAL codes. Our first step was to perform vibrational analyses in a large set of fluoroper- ovskites ABF3. Based on the results, we proposed a model that establishes an A-site geometrically driven ferroelectric vibrational instability in fluorides. Our studies reveal a different behavior as a function of isotropic pressure for NaBF3 with respect to oxides (e.g. BaTiO3) with B = Ca, V, Mn, and Zn. For these compounds we found an increase of the ferroelectric instability as a function of hydrostatic pressure. This probably due to the “transformation” of eigendisplace- ments responsible for the mode that creates the corresponding instability. In particular, an increase of ionic A-site radii present a strong influence in FE-polar instability. We also have shown, based on our first-principles calculations and symmetry theory analysis that all post-perovskites ABX3 with an active magnetic B-site cation can exhibit a noncollinear magnetic configuration, which happens to be allowed by symmetry. With these findings, the magnetic properties found exper- imentally were clarified for this particular high-pressure phase perovskite found at the Earth’s mantle. Additionally, We have predicted that NaMnF3 suffers a structural phase transition under pressure to a post-perovskite phase, where non- collinear ferromagnetism and large magnetic moment components are obtained within this high-pressure phase.. Going beyond, We have shown that it is possible to achieve multiferroic-induced state in NaMnF3 under epitaxial strain at compressive or tensile strain. We found a nonlinear behavior of the ferroelectric instability as well as a non-linear piezo- electric response as a function of epitaxial strain. The later completely different as the one found in oxide perovskites. Similarly, an out-of-plane polarization was observed, a property that has not been observed in oxides. We observed a Na + Mn sites cooperative ferroelectric ordering for compressive strain against a pure A-site geometrically driven ferroelectricity at tensile values of the ac-strain. Magnetic ordering reveals a non-collinear ground state with the GzAxFy repre- sentation. Even more interesting, and non-linear magnetoelectric coupling was found under the strained Pna1 ground state becoming the first known multifer- roic/magnetoelectric perovskite fluoride. Later, in order to go further, We studied the electronic and structural proper- ties of novel heterostructures based on oxyfluorides (KTaO3)n/(KBF3)l B = Zn and Ni interfaces. We found that the orbital levels splitting at the interfaces is strongly modified by the O–B–F coordination. The polar catastrophe phenomena also takes place in the oxyfluoride interfaces similarly to oxide heterostructure, however, we found that less number of layers are needed in order to achieve the insulator-to-metal transition when comparing to SrTiO3/LaAlO3 superlat- tices. We observed that the magnetism in the KTaO3/KNiF3 exhibits a moment magnitude modulations. Nevertheless, the magnetic structure keeps the G-type antiferromagnetism such as in the bulk former compound. Surprisingly, we ob- served a large k3-Rashba type splitting in at the oxyfluoride interfaces, at least four times larger than the one reported in SrTiO3/LaAlO3 interface and twice of the KTaO3-based transistor. In conclusion, we observed that fluorides-perovskites are good prototypes for multifunctional properties as oxides. Therefore, based on the results reported in this thesis, we expect that experimentalist and theoreticians can be motivated in characterization of fluorides, which can lead to a new set of unexplored materials with potential novel applications in electronics. [less ▲]

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See detailDocteur
Poskin, Antoine ULg

Doctoral thesis (2016)

During summer 2011, cattle presented severe hyperthermia combined with dropped milk yield and diarrhoea from unknown origin. In October 2011, blood was collected from cattle presenting these clinical ... [more ▼]

During summer 2011, cattle presented severe hyperthermia combined with dropped milk yield and diarrhoea from unknown origin. In October 2011, blood was collected from cattle presenting these clinical signs in Schmallenberg, a small city in West Germany. A new Orthobunyavirus, responsible for these unspecific clinical signs was identified and named Schmallenberg virus (SBV). Upon November 2011, an epizootic outbreak of abortion, stillbirths and malformed new-born was observed in bovine, ovine and caprine herds in Europe due to transplacental transmission of SBV to the foetus. The SBV vectors are small hematophagous midges of the gender Culicoides. This work contributed to estimate the impact of the SBV epidemic in Belgium (Study 1). On the basis of farmer’s observations, between 0.5% and 4% of calves were aborted, stillborn or malformed due to SBV in 2011-2012. Abortions and stillbirths were not clear consequences of the SBV outbreak in cattle. In sheep, between 11% and 19% of lambs were aborted, stillborn or malformed due to SBV in 2011-2012. Deformed animal was the most important finding of SBV outbreak at herd level and an essential condition for the farmer to send suspected samples to the National Reference Laboratory (NRL) for SBV analysis. The results gathered from the study indicate that SBV surveillance and monitoring should be implemented by SBV RNA detection with rRT-PCR in organs collected from stillborn and deformed calves and lambs born in big herds. The high impact of SBV highlighted in the Study 1 was putatively explained by unknown host supporting the SBV activity. In this respect, the role of pigs had never been evaluated. This was essential considering the suggested role of the domestic pigs in the life- cycle of the SBV-closely related Akabane virus (AKAV) (Huang et al., 2003). The absence of RNAemia after experimental infection of piglets with SBV realized in the Study 2 of the i thesis suggests the absence of obvious role of domestic pigs in SBV life-cycle. The absence of RNAemia is indeed a strong indication that further spread of SBV from the pigs to the Culicoides during a blood meal of the vector is not likely to occur, therefore making impossible an SBV transmission. The limited and temporary seroconversion observed after SBV inoculation in only half of the inoculated piglets and the absence of seroconversion reported in a limited number of field collected samples support this consideration. To prevent SBV progression, it was crucial to further study the pathogenesis of SBV. The Study 1 proved that the most important clinical impact of SBV was the consequence of the malformed new-born; hereto it was particularly crucial to improve the knowledge on the development of the SBV-related teratogenic effects. In this respect, experimental infection of pregnant sheep with SBV constituted an appropriate research approach. An experimental model was therefore essential to standardize. This thesis contributed to the standardization of in vivo experiments (in collaboration with another working group) by determining the minimum infectious dose of an SBV infectious inoculum. This reference infectious serum must contain approximately 20 TCID50 to induce a homogeneous effective infection in sheep. This dose is rather low and could be inoculated by a single Culicoides under natural conditions. Beyond this minimum infectious dose, no dose dependent effect was observed in productively inoculated ewes, either in the duration of the RNAemia, the quantity of SBV RNA detected by rRT–PCR in the blood, or in the number of SBV RNA copies present in the organs collected at necropsy. The experimental model developed (partly) in the Study 3 was used to inoculate pregnant ewes at day 45 and 60 of gestation, and increase the knowledge on SBV transplacental transmission. The inoculation induced the persistence of SBV RNA in placental organs until birth. Schmallenberg virus RNA was recovered from the organs collected at birth from the lambs of both groups. However, the chance to obtain SBV RNA positive placental ii organs was significantly higher when the infectious inoculum was inoculated at day 60 of gestation. Positive organs in lambs included CNS and muscle, but no malformation was observed in new-born lambs. This absence of malformations suggests that SBV inoculation must occur earlier than the day 45 of gestation to produce teratogenic effects in sheep. Also, the persistence of SBV RNA in the foetal envelope is indicative of a putative mean for SBV overwintering. The Study 4 highlighted a 6 month persistent seroconversion in the absence of SBV surinfection. In the meantime, SBV circulation drastically dropped on the field and the absence of SBV circulation could induce the sheep to become seronegative under natural conditions. In the Study 5, the experimental model developed in the Study 3 was used to demonstrate that one single SBV inoculation can induce a protective immunity in sheep that persists during a minimum period of 15 months. This experiment highlights that 2 successive periods of SBV circulation, spared of one year, is not likely to induce malformations on the field the second year. Based on the experience gathered with the closely related AKAV, recurrent outbreaks of congenital events can be expected for a long period. Vaccination of seronegative animals could be used to prevent the deleterious effects of SBV in case of SBV re-emergence. During this epidemic, different surveillance approaches including syndromic surveillance, sentinel herd surveillance, cross-sectional seroprevalence studies and pathogen surveillance in vectors have proven their utility and complementarity and should be considered to continue in the future in order to monitor the SBV dynamic. [less ▲]

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See detailDevelopment and validation of analytical methods based on GC-MS/MC Triple Quadrupole instrument for the analysis of POPs in food and feed matrices
Calaprice, Chiara ULg

Doctoral thesis (2016)

This thesis focused on the development and validation of analytical methods for the de-tection and quantification of Persistent Organic Pollutants (POPs) in biological matrices, namely food and feed ... [more ▼]

This thesis focused on the development and validation of analytical methods for the de-tection and quantification of Persistent Organic Pollutants (POPs) in biological matrices, namely food and feed samples. POPs are a group of chemical compounds listed after the Stockholm Convention in 2001, with demonstrated toxicity and dangerousness for envi-ronment, animals and humans. In this work of thesis, special attention was reserved to some selected POPs: polychlo-rodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), usually referred to as “dioxins”, and polychlorinated biphenyls (PCBs), as there is a big concern about these contaminants in Taranto, a city in the Southern Italy very close to Bari, my home town. Taranto, indeed, is characterized by a large industrial area with a steel mill, several incin-erators and a refinery in few kilometre radius (Di Leo et al., 2014). This work has been done in collaboration with the University of Liège (Belgium) where a consolidated exper-tise in the field of POP measurements was available, especially in terms of dioxin anal-yses. In Chapter 1 the main steps, from sample preparation to data elaboration, of a validated confirmatory method for dioxin and PCB detection in food and feed using gas chromatog-raphy coupled to tandem mass spectrometry Triple Quad instrument (GC-MS/MS Triple Quad) have been described. This method was developed at the University of Liège in the framework of the last updates of the EU Regulation that in 2014 allowed confirmatory quantitative analysis of dioxins with Triple Quad. This method was the starting point of this work of thesis, because it was used for all dioxin and PCB quantifications. In Chapter 2 and chapter 3 alternative clean-up approaches for dioxin analysis in fatty food matrices have been developed using different automated systems. These works have been done in the framework of solvent and time saving for high throughput analytical methods in dioxin analysis. In chapter 2, an already existing automated system, DEXTechTM from LCTech GmbH (LCTech GmbH, Bahnweg 41, 84405 Dorfen, Germany) was used for sample clean-up, but a completely new clean-up approach was developed with this. GC-MS/MS Triple Quad instrument, as well as Magnetic Sector High Resolution Mass Spectrometry (HRMS) instrument were employed for final quantification, to demonstrate the suitability of our newly developed clean-up approaches whatever the instrumental detection. In Chapter 3 PowerPrepTM automated system from Fluid Management System (FMS Inc., 580 Pleasant Street, Watertown, MA 02472, USA) was used and our routine sample clean-up approach was modified in order to enhance the efficiency and to reduce cost and solvent consumption of the analysis. In Chapter 4 the main method for dioxin analysis was adapted for the integration of Dechloranes in the list of the analytes targeted in the regular control for dioxins in food and feed. Dechloranes are a family of 6 organo-chlorinated compounds with structure similar to Mirex, also called Dechlorane, a POP listed in the Stockholm convention. Dechloranes have been found in human blood of people from Europe (Brasseur et al., 2014) and in this work an analytical method for Dechlorane detection was developed and validated to investigate food as a possible route of exposure for humans in Europe, where no production plant has been identified so far. The analytical method was used to analyse 88 food and feed real sample and to give an idea of Dechlorane daily dietary intake. [less ▲]

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See detailStudy of the genetic structure of the African buffalo populations (Syncerus caffer): Impact of its high mobility and of the population fragmentation on its distribution and its interactions with humans
Smitz, Nathalie ULg

Doctoral thesis (2016)

The African continent still hosts a unique diversified megafaunal community. However, phylogeographical patterns of African species have not yet been largely studied, as compared to the North American and ... [more ▼]

The African continent still hosts a unique diversified megafaunal community. However, phylogeographical patterns of African species have not yet been largely studied, as compared to the North American and European species. Moreover, nowadays, the African ecosystems suffer of considerable anthropogenic pressures and of severe climatic modifications. Wildlife population fragmentation resulting from habitat loss, drought, poaching and diseases is currently threatening many African species survivals. The present thesis aimed at investigating the phylogeography and the population genetic structure of the African buffalo (Syncerus caffer) at different spatio-temporal scales (phylogeographical scale vs demographic scale), based on different molecular markers (mtDNA D-Loop region, 17 microsatellites and a large set of ‘Single Nucleotide Polymorphisms’ (SNPs)). The African buffalo is an emblematic key species and provides a powerful model to enhance our understanding of the African biogeography and the species conservation requirements. The aim of the first part of the present work was to reconstruct the evolutionary history of the African buffalo based on the study of the mtDNA D-Loop hypervariable region. More particularly, we aimed at studying the impact of the Quaternary climatic fluctuations on the species distribution (i.e. phylogeographical scale). Moreover, one of our purposes was also to investigate the taxonomic controversies linked to the extreme within species morphological variability, using molecular tools. From a sample set including all four morphologically recognized subspecies roaming the sub-Saharan African continent (hereafter called ecophenotypes), two taxonomic units were supported by genetics. The genetic discontinuity was located between the West-Central (S. c. nanus, S. c. brachyceros and S. c. aequinoctialis) and the South-Eastern populations (S. c. caffer). The low amount of genetic differentiation within each of these two units, or lineages, was attributed to a recent (in evolutionary term) Pleistocene expansion in both lineages, with rapid adaptation to a variety of habitats. Using both microsatellites and a large set of SNPs, the second part of the present thesis aimed at investigating the impact of human activities and recent climatic changes on the population structure of the species (i.e. demographic scale). While mtDNA did not allowed to distinguish finer sub-structuration within the two identified lineages, suggesting high female gene flow at an evolutionary timescale, these last molecular markers allowed to identify eight different populations at the continental level: two in West-Central Africa, three in Eastern and three in Southern Africa. Both ancient (Neolithic revolution) and recent anthropogenic activities were proposed to have shaped the demographic population structure observed in Southern and Eastern Africa. Recently, two of these populations were shown to be under significant genetic drift, following severe demographic bottlenecks. In these two cases, the sharp reduction in the size of the populations was proposed to be linked to disease eradication campaigns and to overharvesting during civil wars. Nevertheless, they did not display a significant loss in heterozygosity, indicating that they are still genetically healthy. Interestingly, at the contact region between the S. c. caffer and the S. c. aequinoctialis savanna ecophenotypes, a population displaying a shared genetic pool was also identified, corroborating the existence of hybrids between the different forms (intermediate morphological characteristics). In conclusion, using various genetic approaches and molecular markers, the present work gained insights into the taxonomy and the evolutionary history of the African buffalo, as well as in its conservation management requirements. [less ▲]

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See detailDéveloppement de procédés sol-gel de fabrication de matériaux de batterie
Eskenazi, David ULg

Doctoral thesis (2016)

Différents procédés, installations et moyens d'analyse ont été développés pour la fabrication de matériaux de batterie Li-ion par procédé sol-gel. Leur objectif est de faciliter l'utilisation industrielle ... [more ▼]

Différents procédés, installations et moyens d'analyse ont été développés pour la fabrication de matériaux de batterie Li-ion par procédé sol-gel. Leur objectif est de faciliter l'utilisation industrielle de ces matériaux. Il s'agit d'un réacteur continu de fabrication de xérogels de carbone sous forme de billes, d'un réacteur de nitruration de phosphates, et d'une technique d'analyse thermique couplée à de la spectrométrie de masse. [less ▲]

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See detailModel-Based Prediction of the Response to Vascular Filling Therapy
Pironet, Antoine ULg

Doctoral thesis (2016)

Vascular filling is one of the most frequent interventions in intensive care units. Its expected effect is to increase cardiac output. However, this increase is only observed in approximately 50 % of ... [more ▼]

Vascular filling is one of the most frequent interventions in intensive care units. Its expected effect is to increase cardiac output. However, this increase is only observed in approximately 50 % of cases. In addition, excessive vascular filling can lead to deleterious effects, such as pulmonary oedema, which increase length of ventilation, stay, mortality and cost. Clinicians are thus looking for indices to provide a priori knowledge of the effect of vascular filling. This thesis focuses on a mathematical model-based approach to predict the response to vascular filling. Mathematical models are sets of equations representing the behaviour of a given system as, for instance, the cardiovascular system. To understand the concept of vascular filling, basic elements of cardio-vascular anatomy and physiology are presented in the first part of this thesis. Then, fur- ther details about vascular filling therapy are given, as well as the current indices used by clinicians to predict its effects. The static indices are easy to obtain, but do not perform well. The dynamic indices, based on cardio-pulmonary interac- tions, perform better, but are difficult and highly invasive to implement clinically. A new index, total stressed blood volume, also seems to perform well, but is not easy to obtain clinically. This work develops and then uses models of the cardio- vascular system to make this parameter available to clinicians. Building on the elements of physiology provided in the first part, the second part of this thesis describes ways to model the components of the cardio-vascular system as lumped elements, such as chambers, valves and resistances. Two mod- els of the cardio-vascular system, comprising respectively three and six cham- bers, are built from such elements. These two models involve a small number of parameters, including the total stressed volume in the model. The third part of this thesis describes the potential and methods to identify the parameters of the two cardio-vascular system models. Parameter identifica- tion aims at finding the parameter values that make model simulations as close as possible to measured data. The available data is thus first described, accord- ing to whether it is collected in an experimental laboratory or an intensive care unit. Then, it is mathematically demonstrated that all model parameters can the- oretically be identified from data available in an intensive care unit. However, practically speaking, some parameters are difficult to identify, because they have little influence on the simulations, or have the same effect as other parameters. Fi- nally, computational methods to perform parameter identification are presented and compared. The last part of this thesis presents two applications of the cardio-vascular system models to experimental data. First, all parameters of the six-chamber cardio-vascular system model are identified from data recorded during a preload reduction experiment. This result provides the first quantitative validation of the six-chamber model in transient conditions. Second, all parameters of the three-chamber cardio-vascular system model, including total stressed volume, are identified from data recorded during vascular filling experiments. The total stressed volume parameter is shown to be systematically related to the change in cardiac output after vascular filling. This last index thus provides, for the first time, a model-based means of predicting the response to vascular filling. [less ▲]

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See detailTherapy of Adult T-cell Leukemia by inhibition of the DNA repair mechanisms
Carpentier, Alexandre ULg

Doctoral thesis (2016)

The Tax oncoprotein plays a central role in viral persistence and pathogenesis of human T-cell leukemia virus type 1 (HTLV-1). Indeed, Tax transforms primary cells and induces tumors in transgenic mouse ... [more ▼]

The Tax oncoprotein plays a central role in viral persistence and pathogenesis of human T-cell leukemia virus type 1 (HTLV-1). Indeed, Tax transforms primary cells and induces tumors in transgenic mouse models. Mechanistically, Tax accelerates the S phase of the cell cycle by firing late replication origins. This modification of the replication timing program induces an oncogenic stress that generates DNA damage such as double-strand breaks. Tax thus provides a selective advantage that promotes proliferation but also exposes host cells to potentially harmful clastogenic damage. How Tax-expressing cells handle this oncogenic stress is currently unknown. In this thesis, we show that Tax-expressing cells activate the DNA Damage Response (DDR). We quantified the repair efficiencies of DNA double-strand breaks. We demonstrate that Tax induces the recruitment of DNA repair core proteins (Ku70, RAD51 and RAD52) on chromatin. We further show that the efficiency of homologous recombination (HR) is inhibited by Tax. In contrast, non-homologous end joining (NHEJ) and single-strand annealing (SSA) are activated in the presence of Tax. Taking advantage of the addiction of Tax-expressing cells on improved DNA repair, we show that pharmacological inhibition of these pathways in HTLV-1 infected lymphocytes leads to an accumulation of DNA damage and apoptosis. We propose a novel therapeutic approach for the treatment of ATL based on the use of inhibitors targeting DNA repair pathways. [less ▲]

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See detailApplication de l’échographie à l’étude de la dynamique folliculaire lors de l’oestrus induit chez la vache Azawak au Niger
Moussa Garba, Mahamadou ULg

Doctoral thesis (2016)

Le Niger dispose d’énormes potentialités en matière d’élevage bovin notamment. Mieux exploitées et gérées, elles pourraient améliorer de manière très significative les performances des races locales. Les ... [more ▼]

Le Niger dispose d’énormes potentialités en matière d’élevage bovin notamment. Mieux exploitées et gérées, elles pourraient améliorer de manière très significative les performances des races locales. Les faibles performances de production et de reproduction qui caractérisent le bétail nigérien sont imputables à plusieurs facteurs, notamment les déficiences alimentaires, le mauvais état sanitaire et le faible potentiel génétique des races locales. L’alimentation du cheptel dont dépendent les productions, reste largement tributaire du régime des pluies dont les faibles quantités généralement enregistrées rendent aléatoire la production fourragère. De même, le faible taux de couverture sanitaire entraine la persistance de certaines maladies (PPCB, pasteurellose, tuberculose, parasitoses, mammites..) contribuant ainsi à la baisse des performances de production et de reproduction. La race bovine Azawak, la meilleure laitière produit à peine 7 à 8 litres de lait par jour. Au cours de ces dernières décennies, plusieurs stratégies et programmes de développement ont été élaborés et mis en oeuvre en vue de valoriser les productions animales. Cependant, la mise en oeuvre de ces stratégies et programmes de développement n’a pas permis d’améliorer la performance du secteur de l’élevage et certains indicateurs comme la consommation de viande et de lait par habitant ont diminué de manière drastique. En dépit d’un cheptel bovin numériquement important (+ de 11 millions de têtes), le Niger enregistre un déficit laitier important. La production locale est loin de couvrir les besoins de la population. La présente étude est une contribution visant à terme à augmenter la production laitière par le recours à l’insémination artificielle dont il restait cependant à : - faire le point sur les caractéristiques et performances de reproduction de Bos indicus ; - évaluer les caractéristiques physiologiques et pathologiques du tractus génital de la femelle Bos indicus ; - décrire par échographie les caractéristiques de la croissance folliculaire et de l’ovulation chez des femelles Azawak dont l’oestrus a été induit par une PGF2α ou par des progestagènes. La documentation sur les caractéristiques et performances de reproduction des zébus africains est peu nombreuse. Ainsi, une synthèse a été réalisée pour dresser l’état des lieux des connaissances dans le domaine de la reproduction de Bos indicus. Compte tenu des faibles performances de reproduction de Bos indicus, et pour recourir à l’insémination artificielle, divers traitements hormonaux sont envisagés. Ce travail a également actualisé les résultats potentiels offerts par l’insémination artificielle réalisée sur chaleurs naturelles ou induites. L’infécondité est une des caractéristiques de l’élevage bovin en Afrique se traduisant par un allongement de l’âge du premier vêlage et de l’intervalle entre vêlage. Elle limite le progrès génétique et la rentabilité des élevages de Bos indicus. Pour comprendre si les pathologies du tractus reproducteur constituent un facteur de risque d’infécondité dans le bétail nigérien, une étude a été conduite à l’abattoir de Niamey au Niger. Elle a concerné 500 tractus génitaux de 500 femelles zébus (Bos indicus) appartenant à quatre races bovines (Azawak, Bororo, Djelli, Goudali). Ces vaches et génisses, âgées en moyenne de 8 ± 2,5 ans, ont eu une note d’état corporel moyenne de 1,6 ± 0,6 et un poids moyen de carcasse de 113 ± 21 kg. Aucune différence significative n’a été observée entre les races étudiées en ce qui concerne le diamètre du col (3,4 ± 1,1 cm), la longueur du col (8,1 ±2,5 cm) et des cornes (21,6 ± 5,2 cm), le diamètre des cornes (1,6 ± 0,5 cm), la longueur et la largeur de l’ovaire droit (19,8 ± 4,4 mm et 11,2 ± 3,8 mm) et de l’ovaire gauche (18,8 ± 4,5 mm et 10,2 ± 3,3mm) et le poids des ovaires gauche et droit (2,5 ± 1,6 et 2,9 g ± 1,8 g respectivement). Ces données sont d’une manière générale, inférieures à celles classiquement rapportées pour le genre Bos taurus. Diverses pathologies de l’appareil génital (kystes, infections utérines, free-martinisme, pyomètre) ont été observées sur 10,4 % des tractus génitaux. La fréquence observée des pathologies donne à penser qu’elles ne constituent pas un facteur de risque majeur de l’infécondité. Ce résultat à amener à étudier l’effet des traitements hormonaux sur la croissance folliculaire et l’ovulation. En effet, la croissance folliculaire jusqu’à l’ovulation après synchronisation et induction des chaleurs au moyen de PGF2α et de progestagènes a été appréciée par échographie chez 42 vaches en lactation de race Azawak. Ces animaux issus de la station de Toukounous ont été ensuite inséminés deux fois (à 12 heures et à 24 heures) 5 après la détection de l’oestrus sur respectivement 16 et 11 femelles traitées à la PGF2α et aux progestagènes. Cette investigation à permis de noter les constats suivants : Les taux moyens d’induction ont été de 81 % dans les deux traitements. Le délai moyen d’apparition de l’oestrus est apparu significativement plus long après injection d’une PGF2α (84,8 ± 26,0 heures) qu’après retrait du PRID (59,2 ± 5,8 heures). La durée moyenne de l’oestrus a été plus courte après son induction au moyen de la PGF2α (12,6 ± 2,6 heures) que du progestagène (22,9 ± 2,7 heures) ; Le délai d’ovulation à partir des chaleurs n’a pas été significativement différent chez les animaux traités à la PGF2α (30,3 heures) et aux progestagènes (28,4 heures) ; Le taux de gestation après une injection de PGF2α (31,2 %) a été inférieur à celui obtenu après utilisation du protocole à base de progestagènes associé à une injection de PGF2α et d’eCG (54,5 %). Les intervalles observés entre les traitements et l’oestrus et l’ovulation permettent de préconiser une insémination plus précoce des animaux traités au moyen de progestagènes qu’avec une PGF2α. [less ▲]

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See detailRégulation de la transcription du virus T-lymphotrope humain de type I (HTLV-1) par le complexe MiniChromosome Maintenance 2-7 (MCM2-7)
Barez, Pierre-Yves ULg

Doctoral thesis (2016)

First oncogenic retrovirus discovered, the human T-lymphotropic virus type 1 (HTLV-1) infects approximately 5 to 10 millions of individuals worldwide. HTLV-1 is the etiological agent of adult T-cell ... [more ▼]

First oncogenic retrovirus discovered, the human T-lymphotropic virus type 1 (HTLV-1) infects approximately 5 to 10 millions of individuals worldwide. HTLV-1 is the etiological agent of adult T-cell leukemia and a neurodegenerative disorder called HAM/TSP (HTLV-1 associated myelopathy/Tropical spastic paraparesis). The HTLV-1 Tax protein interacts with the minichromosome maintenance MCM2-7 helicase, through the amino-terminal part of MCM3. This interaction accelerates firing of late DNA replication origins (ORI) in infected cells. Since Tax acts on the long terminal repeat (LTR), we hypothesized that the MCM2-7 complex could also be recruited to the viral promoter. Using chromatin immunoprecipitation, we show that MCM2-7 indeed interacts with LTR sequences. However, loading of the MCM complex does not fire DNA replication in an autonomous plasmid replication assay. In contrast, MCM2-7 activates viral transcription in luciferase reporter assays and in the context of a proviral clone. Short hairpin RNA interference of MCM2-7 inhibits LTR-driven Tax transactivation in lymphocytes. Finally, siRNAs targeting MCM3 reduce viral transcription in HTLV-1 infected cell lines. Together, our data thus indicate that the presence of the MCM2-7 complex on the HTLV-1 promoter is involved in viral transcription. [less ▲]

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See detailExpression des propriétés biologiques des substances humiques de lixiviats sur le développement racinaire de ligneux
Tahiri, Abdelghani ULg

Doctoral thesis (2016)

Humic substances (HS) are a dark-colored heterogeneous organic compounds originated from microbial decomposition and chemical degradation of organic matter. The exact structure and composition of HS ... [more ▼]

Humic substances (HS) are a dark-colored heterogeneous organic compounds originated from microbial decomposition and chemical degradation of organic matter. The exact structure and composition of HS macromolecules are not totally elucidated due to their complexity and their structural heterogeneity. They have long been recognized as plant growth promoting substances, particularly with regard to influencing nutrient uptake, root growth and architecture and by improving soil structure. However, the molecular mechanisms through which HS influence plant physiology are not well understood and must be deepened. The aim of this doctoral thesis is to obtain deeper understanding of the biological activity exerted by HS extracted from landfill leachates in comparaison to a commercial formulation extracted from leonardite on roots growth of woody plants in relation to their chemical characterization and mechanisms of action. Three experimental approach have been carried out. The first one concerns a comparative chemical characterization of total HS and derived fractions, separated in function of their solubility and molecular weight, was performed using elemental analysis, UV-vis, FT-IR and 1H NMR spectroscopy and MALDI-TOF mass spectrometry. Obtained results indicate that HS of both origins were basically similar regarding the presence of their chemical structures but, differ mainly in their relative abundance. The second, concerns the development of an in vitro culture model to study the biological activity of HS on the development of root system of two woody pioneer species. The data obtained showed that the effect of HS depends on plant species, concertation, mode of application and source of HS. If the high molecular weight fraction (HA) was effective at promoting root development, the lower ones (FA and OM) inhibit it in function of the concentration used. Finally, a molecular approach was investigated to study some molecular mechanisms that plant act in response to HS comparing the expression of four genes (ABCB1, ABCB19, GS and ADH) implicated respectively in auxin, nitrogen and carbon metabolisms. Obtained data show that HS and their HA fractions influence root growth and development apparently by influencing different mechanism of regulation associated with polar auxin transport, the incorporation of inorganic nitrogen as glutamate, carbon metabolism and abiotic stress responses. Results presented in this thesis showed that landfill leachates HS especially their HA fraction can be valued as bio-stimulant of plant growth. [less ▲]

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See detailDEVELOPMENT OF PHARMACOLOGICAL TOOLS FOR THE IDENTIFICATION OF G PROTEIN-COUPLED RECEPTORS LIGANDS
Gilissen, Julie ULg

Doctoral thesis (2016)

G protein-coupled receptors (GPCRs) represent the protein family most successfully targeted for treating human diseases. They couple to G proteins to mobilize second messenger pathways that lead to ... [more ▼]

G protein-coupled receptors (GPCRs) represent the protein family most successfully targeted for treating human diseases. They couple to G proteins to mobilize second messenger pathways that lead to cellular responses and ultimately to physiological changes. However many are poorly characterized with few ligands reported or remain completely orphans. Therefore, there is a growing need for screening-compatible and sensitive assays in order to identify new ligands. The present project aims at developing pharmacological tools to characterize the pharmacology and physiology of GPCRs. Our approach rely on i) development of receptor models and assays for the identification of ligands, ii) screening of chemical and virtual small molecules libraries and iii) analysis of structure-activity relationships study of active molecules. The project has been divided in two parts. To set-up assays for the evaluation of GPCRs activation, we selected the understudied succinate receptor 1 (SUCNR1) that is proposed to affect cellular metabolism and pathophysiology of diseases in multiple organs. Nevertheless the receptor has never been validated as a drug target because very few ligands have been described. So, developing pharmacological tools for SUCNR1 remains of great interest in therapeutic drug discovery. First, we have started by examining SUCNR1 signaling pathways in HEK293 cells. Our investigations have highlighted the efficient coupling to Gαi and thus the negative modulation of intracellular cAMP levels. Consequently we have implemented an assay sensitive to cAMP variations to identify ligands able to induce SUCNR1 activation. However, an important drawback to track agonists for Gαi-coupled receptors is the mandatory stimulation of cAMP levels. Inducers such as forskolin must be used and are sources of variations and errors. In order to avoid these artifacts we have set-up and validated a cAMP-inducer free method based on the GloSensor biosensor. This real time assay was amenable to high-throughput screening for the detection of Gαi-coupled receptors agonists. The strategy monitoring basal cAMP levels compared to the stimulated cAMP levels allowed to decrease recording time and artifcats from forskolin use, leading to the identification of fewer false positives and unidentified false negatives. Although both methods found agonists in the chemical library screened, no active new scaffolds on SUCNR1 were discovered. We infer that this method could facilitate the study and screening of Gαi-coupled receptors for active ligands. Secondly, given the interesting potential of SUCNR1 for promising therapeutic advances, we have carried out the study of the receptor interaction with its natural ligand, succinate. We have optimized the previous three-dimensional model for SUCNR1 binding pocket by means of more detailed structure-activity relationships study of succinate related molecules. The study of structure-activity relationships performed by Pierre Geubelle, in parallel to this work, allowed the deduction of the structural elements required to be active on SUCNR1. Thus we have defined a pharmacophore for activity on the receptor and subsequently evaluated various cycloalkanes. With our cAMP assay, Pierre Geubelle has highlighted the (1R, 2S)-1,2-cyclopropanedicarboxylate to be able to activate SUCNR1. We confirmed the activity of this compound on SUCNR1 capacity to recruit arrestin 3 and determined the pharmacological properties of this new ligand as SUCNR1 agonist, in vitro and in vivo. To confirm our in vitro results, we have also assessed the hypertensive properties of this cyclic analogue. Intravenous addition at the dose of 0.1 mg.kg-1 in rats has been demonstrated to increase blood pressure in the same range as succinate. Consequently we have demonstrated that (1R, 2S)-1,2-cyclopropanedicarboxylate could be regarded as an original synthetic full agonist for SUCNR1. In addition, the pharmacophore for SUCNR1 should help to generate synthetic compounds characterized by an increased potency and/or efficacy compared to succinate. [less ▲]

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See detailẾtude de l’émergence des organisations pastorales et de leur rôle dans les processus de gestion partagée de la vallée de la Tarka dans les départements de Bermo et Dakoro (Centre sud du Niger)
IBRAHIM, Habibou

Doctoral thesis (2016)

Cette thèse vise à analyser les organisations pastorales et leurs rôles dans la gestion des conflits fonciers. En Afrique subsaharienne et particulièrement au Niger, le foncier est au centre des enjeux de ... [more ▼]

Cette thèse vise à analyser les organisations pastorales et leurs rôles dans la gestion des conflits fonciers. En Afrique subsaharienne et particulièrement au Niger, le foncier est au centre des enjeux de l’agro-pastoralisme. La sécurisation des droits d’accès aux ressources et des systèmes de tenure foncière sont essentiels pour la gestion et la résolution des conflits fonciers (Herrea et al., 2007). La région de Maradi constitue la zone de contact entre le Nord pastoral et le Sud agricole. Dans cette partie centrale où la pression foncière, aggravée par la croissance démographique, se pose avec acuité, le spectre des conflits fonciers est malheureusement devenu un phénomène chronique, une donnée permanente (GADO., 2000). La pluralité des normes et plusieurs sources de droit contribuent à complexifier le règlement des litiges fonciers entre acteurs dans les départements de Dakoro et Guidan Roumdji (Moutari., 2001). Or la dynamique globale des systèmes d’élevage est déterminée par la complémentarité des espaces agro-pastoraux. Cette complémentarité est remise en cause par ces pressions foncières et suscite des changements organisationnels dans les communautés du centre Sud du Niger (Yamba., 2004 ; 2000). C’est le rôle des associations pastorales à Dakoro et Bermo qui est l’objet de cette recherche. En effet les organisations paysannes en Afrique Subsaharienne et au Niger en particulier jouent un rôle important dans la définition des politiques agricoles et deviennent des conditions indiscutables de la réussite des actions à promouvoir à l’échelle locale (Courade et Deveze., 2006 ; Mercoiret, 2006 ; Mercoiret et al. 2004). La méthodologie de travail relève de l’approche ethnographique. Les outils et instruments d’enquête sont les questionnaires et les entretiens ouverts avec les acteurs locaux sur les dynamiques territoriales, les modes d’action des associations pastorales et les conflits fonciers. Les résultats viennent aussi des travaux et des documents des projets, des ONG et des rapports des services techniques de l’Etat. Pour un souci de fiabilité des données, nous avons tenu à réaliser des séances de restitution des données et de triangulations pour confronter les informations de diverses sources. Au total 104 personnes sont enquêtées dont 30 % auprès des associations. Ces investigations ont concerné aussi les secrétaires des commissions foncières, les préfets, les agents des projets et des ONG et le président du tribunal de Dakoro ainsi que les leaders pastoraux, les transhumants, les agriculteurs et associations pastorales. [less ▲]

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See detailCaractérisation et tests de traitement des déchets ménagers et boues de vidange par voie anaérobie et compostage pour la ville de Kinshas
Mindele Ukondalemba, Léonard ULg

Doctoral thesis (2016)

Dans les pays en développement (PED) en général et en République Démocratique du Congo en particulier, la problématique de l’assainissement (eaux usées et des déchets solides) constitue un enjeu majeur ... [more ▼]

Dans les pays en développement (PED) en général et en République Démocratique du Congo en particulier, la problématique de l’assainissement (eaux usées et des déchets solides) constitue un enjeu majeur pour les spécialistes et les autorités locales. Cette thèse a comme objectif général de faire une évaluation de l’état des lieux et de dégager des pistes possibles de traitements des déchets solides et liquides en vue de protéger les populations et de s’orienter vers des traitements qui respectent au mieux les principes du développement durable. Pour réaliser cet objectif, il a été question de caractériser les déchets municipaux solides, spécialement des déchets ménagers, par une méthode de caractérisation rapide, simple et peu couteuse. Pour ce qui concerne la gestion des eaux usées, spécialement les boues de vidange provenant de l’assainissement non collectif (ANC), par une méthode sociologique mobilisant des techniques d'enquêtes et d'observation sur site, qui a permis de bien comprendre les pratiques d'assainissement non collectif sur terrain dans le contexte de la République démocratique du Congo ; enfin d’un essai de traitement par une digestion anaérobie (ou co-digestion anaérobie) des déchets suivi du compostage (ou co-compostage).Parmi les modes de traitement de déchets, la digestion anaérobie paraît être une option attrayante pour la dégradation des déchets ménagers fermentescibles en produits utiles tels que le biogaz et le compost de haute qualité. De ce fait, nous avons mené une étude expérimentale comparative entre la digestion anaérobie des déchets ménagers fermentescibles uniquement et la co-digestion anaérobie des déchets ménagers fermentescibles et de boues de vidange de fosse septique. L’expérience a été conduite dans deux cuves de 80 litres. La digestion et la co-digestion anaérobies se sont déroulées à la température de 25°C et en deux étapes, de sorte que la première étape dans la cuve de 80 L, s’arrête à l'acidogenèse et que la deuxième étape se passe dans un autre digesteur de 10 L allant de l’acétogenèse à la méthanogenèse. Les résultats ont montré que 1,3 Nm3 de méthane sont produits à partir de la digestion anaérobie des déchets uniquement et 1,8 Nm3 de méthane sont produits à partir de la co-digestion des déchets et des boues de vidange, confirmant l’intérêt de la co-digestion.Les résultats préliminaires trouvés sont encourageants, notamment en matière de gain detemps dans la durée du processus. Le procédé a entre autres avantages de limiter la manipulation du déchet en cours de traitement et de fournir à la fin deux produits directement valorisables : le compost et le méthane. Bien entendu ces résultats préliminaires devront être validés par des essais à une échelle un peu plus grande avant de proposer de passer à des projets en vraie grandeur. Ainsi nous espérons que ce travail pourra contribuer à la relance des digesteurs anaérobies pour favoriser les énergies renouvelables tels que prôné ce dernier temps par la COP21 et ainsi éviter la déforestation intempestives des nos forets. Mots clés : assainissement non collectif, déchets solides fermentescibles, boue de vidange, co-digestion anaérobie, indicateur d'assainissement, digestion anaérobie, compost. [less ▲]

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See detailPrincipal static wind loads within a rigorous methodology to the envelope reconstruction problem
Blaise, Nicolas ULg

Doctoral thesis (2016)

Static wind loads are being used for the design of large civil structures such as high-rise buildings, large roofs and long-span bridges. Once static wind loads are known, they are used through the ... [more ▼]

Static wind loads are being used for the design of large civil structures such as high-rise buildings, large roofs and long-span bridges. Once static wind loads are known, they are used through the iterative design process without repeating cumbersome dynamical analyses. In this framework, structural engineers can effectively focus on the structural sizing since static analyses are straightforward. No codified wind loads, however, exist for those large structures with unique shapes and there is no consensual view on how to formally derived them. For each new major project, the challenge consists therefore in deriving a relevant set of static wind loads. Obviously, these loads must provide the actual envelope values of structural responses of interest. This states the objective of the envelope reconstruction problem and constitutes the core of this thesis. The proposed developments to solve this problem are relevant for structures responding with a linear dynamic behavior to the buffeting action of synoptic winds in a stationary framework. The pioneering concept of Equivalent Static Wind Load is normally considered for the design. An extensive review points out two main limitations of the current formulations. They have been originally established in a Gaussian context, are associated with either a nodal or nodal-modal basis and do not have a formal definition. The proposed Conditional Expected Load method overcomes the three drawbacks by defining a Conditional Expected Static Wind Load. This novel approach presents a general rigorous formulation for linear structural behavior, irrespective of the basis used for the analysis and relevant in a non-Gaussian context. The method is particularized for a certain class of non-Gaussian processes through a bicubic translation model. This model covers a large range of non-Gaussianity in the random processes and therefore paves the way for the formal establishment of “non-Gaussian” static wind loads with a physical interpretation. Other kinds of static loads such as the covariance proper transformation loading modes and the modal inertial loads are additionally studied. Unfortunately, both sets of loads are simply relevant for two limit structural behaviors, quasi-static and resonant, respectively. Moreover, they do not adapt to the set of structural responses of interest. From both points of view, one key result from our study is the innovative concept of Principal Static Wind Load as a sound solution for the envelope reconstruction problem. The concept relies upon a robust mathematical foundation. These loads are determined by the singular value decomposition of a large set of equivalent static wind loads. This decomposition can be seen as a way to rank the most relevant load patterns for the envelope reconstruction problem. The principal static wind loads have also the added distinctive advantage to be flexible. They are, indeed, able to naturally adapt to the set of structural responses of interest. Finally, a complete methodology to solve the envelope reconstruction problem irrespective of the structure, its load-bearing system and its susceptibility to vibrations in a Gaussian or non-Gaussian context is rigorously conceptualized. The intrinsic controllability of a set of pertinent parameters provides a smart balance between over and underestimation of the actual envelope. Moreover, combinations of static wind loads are computed to speed-up the reconstruction of the envelope values. The problem of determining these combination coefficients is formulated as a constrained nonlinear optimization. Equivalent and principal static wind loads, covariance proper transformation loading modes and modal inertial loads are implemented within the proposed methodology. Three examples: a four-span bridge, a real-life large stadium roof and a low-rise building demonstrate that the envelope reconstruction accuracy is considerably improved with principal static wind loads and with combinations thereof. [less ▲]

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See detailEvaluation des charges polluantes (domestiques et industrielles) arrivant au lac Kivu dans la ville de Bukavu, RD. Congo
Lina Aleke, Alex ULg

Doctoral thesis (2016)

Dans les pays en développement (PED) en général, et plus particulièrement en République Démocratique du Congo (RDC), le développement des villes et l'augmentation des populations urbaines se font avec une ... [more ▼]

Dans les pays en développement (PED) en général, et plus particulièrement en République Démocratique du Congo (RDC), le développement des villes et l'augmentation des populations urbaines se font avec une rapidité telle que l'accessibilité à l'eau potable et à l'assainissement de basepose un problème croissant de sante publique et de bien-être des populations. Le manque d'expertise et des moyens techniques et/ou financiers ne permet pas de mettre en place des programmes cohérents et adaptés aux réalités et défis que connaissent ces pays. C'est dans cette optique que la présente étude qui porte sur la caractérisation des eaux résiduaires domestiques et industrielles générées dans la ville de Bukavu, a été menée en vue d'évaluer les flux des pollutions arrivant dans le lac Kivu. Différents axes de recherche ont été ainsi exploités pour répondre a cet objectif. Ce sont :l'évaluation de l'assainissement non collectif (ANC),la caractérisation des flux polluants générés par les activités domestiques et industrielles, etl'analyse critique des atouts naturels (physiques, géologiques, hydrogéologiques, etc.) de la ville de Bukavu en vue de mettre sur pied des filières permettant un assainissement correctet la protection du lac Kivu. L'évaluation de l'assainissement a été basée sur une démarche sociologique faisant appel à des techniques d'enquêtes et d'observation deterrain. Une approche d’évaluation par un indicateur découlant de la combinaison des indicateurs mis en place au prorata des trois maillons composants une filière d’ANC (amont, intermédiaire et aval) a été utilisée. Les résultats obtenus montrent un faible niveau d'accès à l'eau potable et à l'assainissement de base qui serait lié à des facteurs historiques, physiques, politiques, et socio-économiques. De plus, un effort considérable reste à faire pour la gestion du maillon aval car la gestion des boues produites se fait pour le moment de manière non conforme. Par ailleurs, la densité de la population, en pleine croissance, nécessite une politique de construction de logements bien appropriée. Réalisée au niveau des émissaires domestiques (ITFM, Rukumbuka, PIR, Nyamugo et Bagira) et des rivières (Bwindi, Tshula, Wesha et Kahwa) qui traversent Bukavu, la caractérisation des flux de pollutions domestiques a été menéeau travers des méthodes physicochimiques et microbiologiques. Elle a permisd'apprécier l'importance des risques sanitaires qu'encourent les habitants de Bukavu dans leur quotidien, ainsi que l'ampleur des pressions que subit le lac qui en est le réceptacle. De la même manière, notre étude s'est intéressée aux flux produits des pollutions industrielles brassicoles et pharmaceutiques, suivant une approche physicochimique. Il ressort de ces analyses que les émissaires domestiques constituent le cadre de premier choix adopté par les habitants pour le rejet de leurs déchets. Ce faisant, les rivières de la ville font l'objet d'importantes pollutions engendrées par les activités domestiques, et constituent des égouts à ciel ouvert. Les flux évacués et arrivant quotidiennement dans le lac vont de 2165 kg (rivière Bwindi) à 5974 kg DBO5 (riviere Kahwa) en saison sèche, et de 5303 kg (rivière Bwindi) à 14270 kgDBO5 (rivière Kahwa) en saison de pluie, correspondant aux charges totales respectives de 7468 kg DBO5 et 20244 kg DBO5. Les flux des pollutions microbiologiques ont été évalués a 2,3.109 UFC/EH DBO5 pour la rivière Bwindi et 6.109 UFC/EH DBO5 pour la rivière Kahwa en ce qui concerne les coliformes fécaux, et 2800 œufs/EH DBO5 (rivière Bwindi) et 4185 œufs/EH DBO5 (rivièreKahwa) pour les parasites.En outre, 11 taxons de parasites ont été identifiés. Ce sont : Entamoeba coli, Giardia lamblia, Entamoeba histolytica, Ascaris sp. (taxon le plus distribué), Ankylostoma sp., Strongyloides sp., Trichuris trichiura, Hymenolepis nana, Hymenolepis diminuta, Taenia saginata et Schistosoma mansoni. Recevant les eaux de 4 de 5 émissaires domestiques étudiés, la rivière Kahwa s'est avérée comme la plus polluée des rivières de Bukavu. Concernant les pollutions industrielles, pour chaque litre de boisson (bières et boissons gazeuses confondues), la société brassicole Bralima utilise entre 4,7 et 5,7 l d'eau, avec une moyenne de 5,1 l.Les pollutions spécifiques s'établissent entre 1,2 et 1,6 kg DCO/hl, et 0,2 et 0,4 kg MES/hl de produits finis, avec unecharge globale évaluée 194,1 kgDCO par jour, avant traitement. L'abattement des pollutions dans la station d'épuration de cette société brassicole devrait être amélioré en vue de réduire ses pressions sur le lac et les risques sanitaires auxquels sont exposées les populations. Quant à la Pharmakina, la charge globale des pollutions, évaluée à 1229,2 kgDCO par jour, arrive dans le lac Kivu sans aucun traitement préalable, constituant ainsi de graves menaces environnementales et écologiques imputables à sa responsabilité. [less ▲]

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See detailPerturbations of interactome networks in acute lymphoblastic leukaemia: identification of EXT1 tumor suppressor as a Notch pathway regulator
Daakour, Sarah ULg

Doctoral thesis (2016)

Whole genome sequencing technologies have enabled the identification of mutations implicated in diseases including cancer. Recently, research efforts to compare and categorize mutations, genes expression ... [more ▼]

Whole genome sequencing technologies have enabled the identification of mutations implicated in diseases including cancer. Recently, research efforts to compare and categorize mutations, genes expression and genomic characteristics helped generating literature-curation databases. A large number of databases were developed to address data integration and standardization for human cancers, such as Catalogue Of Somatic Mutations In Cancer (COSMIC), The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium, Integrative Onco Genomics (IntOGen). Although the identification of these mutations highlights “cancer causative genes”, it does not give a detailed explanation of molecular mechanisms leading to the development of cancer. Though, understanding mechanisms leading to cancer development and progression remains a challenge that requires further investigations. The great majority of mutated genes are found in liquid tumors such as leukemia and lymphomas. In the first part of this study, we reasoned that leukemia associated genes could be extended to additional candidates identified using interactomic approaches. We used protein-protein interaction (PPI) mapping strategies to explore information on cancer genes frequently mutated in Acute lymphoblastic leukemia (ALL). We first extracted mutational data associated to ALL, and used interactome mapping analysis for literature-curated interactions and yeast two-hybrid experimental data in order to identify potential novel target genes associated with ALL. We highlighted mutated hub proteins interconnected in an ALL-cancer gene products network and identified novel interacting partners that link key ALL-cancer driver gene products. We identified EXT1 tumor suppressor gene as a novel common interactor for NOTCH1 and FBXW7. In the second part of this study, we experimentally validated EXT1, as a novel player in the regulation of the Notch pathway. Our study thus provides a proof-of-concept on how systematic interactome approaches could allow identification of novel targeted genes and pathways associated to human cancer. [less ▲]

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See detailEpidemiological Study of Canine Leishmaniasis in Algeria and its Impact on the Human Visceral Leishmaniasis
Adel, Amal ULg

Doctoral thesis (2016)

Zoonotic visceral leishmaniasis (VL), caused by Leishmania infantum is a vector-borne disease, transmitted to humans by the bite of infected female phlebotomine sand flies. In absence of treatment the ... [more ▼]

Zoonotic visceral leishmaniasis (VL), caused by Leishmania infantum is a vector-borne disease, transmitted to humans by the bite of infected female phlebotomine sand flies. In absence of treatment the outcome is death. The disease is characterised by irregular fever bouts, loss of weight, hepatosplenomegaly and anaemia. It is endemic in the Indian sub-continent and in East Africa. In the Mediterranean region, it is present in rural areas, in villages, in mountain areas, but also in certain peri-urban zones, where the parasites survive in dogs and other mammals. In fact, domestic dogs are the principal reservoir of human VL and they also can develop a more generalised and fatal form of the disease, although more than half of the dogs remain asymptomatic, the individual outcome depending on both cellular and humoral immune responses. Both symptomatic and asymptomatic dogs can infect the phlebotomine vectors, thereby enabling the transmission to other dogs or to people. This is the main reason why early detection and treatment of infected animals is the best way to reduce the risk of infection and, as such, forms an essential component in the prevention and control of the human disease. Ideally, a so-called “gold standard” test is required to reliably and correctly determine the infectious status of an individual and/or the infection prevalence in a population in a certain region at a certain point in time. A gold-standard test provides an error-free classification of individuals as infected or infection-free. The discriminative power of a real-life test is quantified by measures of precision, more specifically the sensitivity and the specificity of the test. They vary in function of characteristics of the population studied. In the majority of cases, a gold standard test does not exist. In order to overcome this lack, use is made of reference tests. The latter are often imperfect (sensitivity and specificity below one) and they allow estimation of a so-called apparent prevalence rather than the actual true prevalence. A statistical solution to the problem of lack of gold standard test consists of a Bayesian approach, which allows us to combine data of a study with external (prior, independent) information, such as results from previous studies or expert opinion. This approach yields an estimate of the true prevalence, as well as estimates of the sensitivity and specificity of the tests used. This thesis attempts to contribute towards a better understanding of the epidemiology of visceral leishmaniasis in Algeria. More specifically, our general objective (Chapter 3) was to estimate the true prevalence of canine leishmaniasis, in a situation where a diagnostic gold standard test was unavailable, and to describe the epidemiological curve and profile of visceral leishmaniasis in the country. With this in mind, the work is organised in nine chapters. The first chapter outlines the importance of leishmaniasis (respectively visceral and canine) in terms of public health and veterinary public health and provides an overview of the current knowledge base on canine leishmaniasis. The second chapter is devoted to a description of the epidemiological methodology available for the estimation of the true prevalence and the test characteristics in the absence of gold standard test. Chapter 4 describes an epidemiological study conducted in the capital city Algiers, comprising 462 dogs subdivided in four groups according to their function (stray dogs, guard dogs, farm dogs and pet dogs). A Bayesian approach was used to estimate the true prevalence of canine leishmaniasis in the four groups and to evaluate three serological tests: an indirect immunofluorescence test (IFAT), a direct agglutination test (DAT) and a commercial rapid test on gel, based on the protein rK39 (PaGIA). We were able to demonstrate variability in the test performance characteristics in the different groups, and this in terms of sensitivity and specificity. IFAT, although it is an imperfect test, is nevertheless the test of choice when the dog population targeted consists of stray dogs, but its specificity drops to a unsatisfactory 65.2% (IC: 60.2-73.5%) when applied to farm dogs: the fact of living together with other animals may induce cross-reactions. Stray dogs also yielded the highest estimate for the true prevalence (11.7%), probably a consequence of their constant living outside, which increases the risk of exposure to infected phlebotomine vectors. Using the above results, a large-scale transversal survey was mounted in six towns of the littoral zone of Algeria (Chapter 5). Thus, a total of 2,184 farm dogs and guard dogs were sampled in two distinct periods using two serological tests: before and after the main vector season, using IFAT and DAT. Serial and parallel interpretation of the combined tests were compared to various other statistical methods in order to estimate the true prevalence and the sensitivity and specificity of the two tests. The latent class model of Hui and Walter based on conditional independence between the diagnostic tests was compared to a Bayesian model, which made it possible to include conditional dependency between tests, if required. The best-adjusted model estimated canine leishmaniasis prevalence between 11% and 38% with an increasing trend from west to east. IFAT sensitivity varied between 86% and 88% in the different localities, whereas specificity ranged between 65% and 87%. DAT was invariably less sensitive than IFAT, but had a better specificity: between 80% and 95% in function of locality and season. The results highlighted once more the danger of considering IFAT to be a gold standard test for canine leishmaniasis. Chapter 6 draws up an epidemiological profile of human zoonotic visceral leishmaniasis in Algeria, based on cases notified to the National Public Health Institute between 1998 and 2008. A total of 1,562 were found for this period. This translates into an incidence rate of 0.45 cases per 100,000 inhabitants, of which 81.4% were children between zero and four years of age. Splenomegaly, fever, pallor and pancytopenia were the principal clinical and biochemical signs. Antimonies are the first-line treatment drugs in paediatric wards and amphotericin B injections are the treatment of choice in adults. Severe under-declaration (less than one case in ten notified) was demonstrated thanks to a survey carried out in the paediatric, internal medicine and infectious diseases departments of the five university hospital centres in Algiers, which had an influx of patients from all four corners of the country. Results of both Chapter 5 and Chapter 6 revealed a concordance between human visceral leishmaniasis incidence rates and true prevalence of canine leishmaniasis, providing extra support for the hypothesis that dogs are the main reservoir of the disease. Motivated by the results of the two surveys (Chapters 4 and 5), Chapter 7 describes a literature review of the performance of IFAT when used to estimate the canine leishmaniasis prevalence in the Mediterranean basin. Chapters 8 and 9 present the general discussion and conclusions and recommendations of the overall contribution of this research effort. Even though this work only represent a small addition to knowledge body on visceral leishmaniasis, it allowed us to better describe and understand the epidemiology of visceral leishmaniasis in Algeria and to obtain true prevalence estimates of canine leishmaniasis in various towns in the littoral zone of the country. It showed us the importance of correctly identifying and defining the target population of surveys to obtain the best possible posterior estimates and to optimise control measures. This work also showed the efficacy of the application of appropriate statistical models in a Bayesian framework when confronted with the absence of a gold standard test. Chapter 10 summarizes all references cited in the thesis. [less ▲]

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See detailFlexibility services in the electrical system
Mathieu, Sébastien ULg

Doctoral thesis (2016)

The work presented in this thesis considers the electrical flexibility from the electric load to its usage as a commodity. The conception of the European electrical system has led to a large amount of ... [more ▼]

The work presented in this thesis considers the electrical flexibility from the electric load to its usage as a commodity. The conception of the European electrical system has led to a large amount of actors that are impacted by flexibility exchanges. This thesis proposes approaches to assess the impact of exchanging flexibility in the electrical system and analyzes the complex interactions resulting from these exchanges. The modeling techniques used to carry the analysis are optimization, game theory and agent-based modeling. The impacts on different parts of the electrical system are presented: the day-ahead energy market, the secondary reserve and the distribution system. Since flexibility is the base block of this thesis, two methods to obtain flexibility from actual consumption processes are broached: direct control of the loads and dynamic pricing. One chapter provides an example of how flexibility can be obtained by the direct control of a portfolio of heat pumps and another chapter studies the control of electric heaters and boilers via the use of a simple price signal. [less ▲]

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See detailStratégies innovantes d’adaptation à la variabilité et au changement climatiques au Sahel : cas de l’irrigation de complément et de l’information climatique dans les exploitations agricoles du Burkina Faso
Zongo, Bétéo ULg

Doctoral thesis (2016)

The Sahelian farmers, the scientific community, government and development partners are actively looking for new farming practices to mitigate the consequences of dry spells probably exacerbated by ... [more ▼]

The Sahelian farmers, the scientific community, government and development partners are actively looking for new farming practices to mitigate the consequences of dry spells probably exacerbated by climate changes. To contribute for this challenge, this research examines the issue of agricultural innovations’ adoption in the Sahelian and Sudano-Sahelian zones of Burkina Faso. Among promoting agricultural innovation, the study explored the possibilities to popularize the practice of supplemental irrigation from individual basins (ICBI) and the use of climate information (CI) in the farms. The approach developed is threefold. Data were collected from farm households through surveys and conducting experimentation of ICBI and use of CI in rainfed agriculture. In addition to the usual descriptive statistics, analysis of variance, the multinomial logit model was used to analyze the determinants of the agricultural innovations dissemination. Determining factors of farmers’ willingness to adopt ICBI were identified using a logistic model. The criteria for partial budgeting were used as tools for assessing the economic viability of ICBI. The Heckman model associated with the contingent valuation approach was used to analyze famers’ willingness to use CI. Simulations were made from a bio-economic model to test some policy instruments for the adoption of these new practices. After four decades of diffusion (1974-2013), the adoption rate is estimated at 69.3% for stone bunds, 49.1% for zaï, 26.2% for grass strips and less than 10% for half-moons, bunds land and mulching. The low level of farmers’ organization and access to agricultural services were the major constraints to their adoption. Over 65% of the farmers believe that ICBI is an effective way to mitigate the adverse effects of dry spells on crop yields. After three years, the experiments showed that this innovation in family farms increases maize yield by 1.08T/ha (88.3%). Maize production surplus achieved with ICBI can fill the monthly cereal requirements of 17 people on average and increases the gross margin by F 178,483 CFA compared to the situation without irrigation. The review of the net present value, internal rate of return and the net benefits increase ratio showed that the profitability to practice supplemental irrigation depends on the types of basins. From the sampled farmers, 93% of them required CI to guide their decision in planning agricultural activities. About 64% of the farmers are willing to pay for CI. The experiments reveal that the surplus of maize and sorghum yield obtained with the use of CI meets the monthly cereal requirement of 7 persons on average compared to traditional seasonal forecasts. The simulations indicate that the ICBI in middle year increases the expected income of 26.5% (F 133 030 CFA) compared to the situation without irrigation. The tested policies include six types of grant and the establishment of a system for granting credit to farm households to finance the supplementary irrigation device. The implementation of these policies should facilitate the adoption of ICBI at a larger scale. The researchers and development actors should pursue the experimentation on the combination of ICBI and CI. [less ▲]

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See detailMultiscale approach of spray retention on superhydrophobic plant surfaces
Massinon, Mathieu ULg

Doctoral thesis (2016)

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See detailIndirect quadrangular mesh generation and validation of curved finite elements
Johnen, Amaury ULg

Doctoral thesis (2016)

Among the different types of 3D finite element meshes, hexahedral meshes present properties that can be highly desirable, such as alignment with physical features or a lower computational cost. For this ... [more ▼]

Among the different types of 3D finite element meshes, hexahedral meshes present properties that can be highly desirable, such as alignment with physical features or a lower computational cost. For this reason and despite the maturity of the tetrahedral mesh generators, hexahedral mesh generation has always been a prolific research domain. Yet, there exists currently no robust algorithm capable of generating conformal all-hexahedral meshes with prescribed input size field on any arbitrary geometry. One difficulty that remains is that there exists no method to robustly assert that a hexahedron is valid. Indeed, linear hexahedra can be folded (tangled) in the same way than curvilinear tetrahedra. This thesis addresses two subjects. First, two original quadrangular mesh generation techniques are investigated, with the aim to generalize them to 3D. Both are indirect methods and thus consider the problem of combining pairs of triangles of an initial input triangular mesh. The first technique, called Blossom-Quad, computes the optimal solution of this problem with respect to a given quality criterion. As for any indirect method, the quality of the solution strongly depends on the location of the nodes in the initial triangular mesh. The generalization to 3D is however unclear and a second technique is investigated. This one aims at computing a near-optimal solution by using a look-ahead tree technique. The corresponding algorithm allows tuning the quality of the final mesh by choosing the depth of the tree as a parameter. This technique gives a promising way forward, especially as it is directly applicable in 3D. The second subject concerns the development of a method that permits to compute, with respect to any prescribed tolerance, the extrema of Jacobian-based quantities defined on finite elements of any order and type. Applied to the Jacobian determinant, this method allows to assert the validity of any (curvi-)linear finite element. This method is also applied to a quality measure that quantifies the pointwise anisotropy of the elements. Besides being very attractive for hexahedral mesh generation, this method is especially useful for the analysis of curvilinear finite element meshes. It can moreover be an important component of optimization techniques for achieving robustness. [less ▲]

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See detailLower Carboniferous shallow marine sequences from the Central Alborz Basin, Iran (north-eastern margin of Gondwana): sedimentology, biostratigraphy and rock– magnetic studies
Sardar Abadi, Mehrdad ULg

Doctoral thesis (2016)

The Lower Carboniferous Mobarak Formation records the development of a carbonate platform on the southern Paleo-Tethyan passive margin. This pervasive carbonate factory was deposited following the opening ... [more ▼]

The Lower Carboniferous Mobarak Formation records the development of a carbonate platform on the southern Paleo-Tethyan passive margin. This pervasive carbonate factory was deposited following the opening of the Paleo-Tethys Ocean into the Alborz Basin along the northern margin of Gondwana. The depositional facies range from the most proximal to the most distal and include coastal environments, inner ramp peritidal facies, peloidal to crinoidal shoals, storm to fair-weather influenced mid-ramps, proximal to distal shell beds and low energy outer ramps. Storms clearly played a dominant role in the distribution of skeletal and non-skeletal shoals on the carbonate ramp. Sedimentological analyses complemented with foraminiferal biostratigraphy reveal four events which are interpreted to represent the principal factors controlling carbonate platform evolution in the Alborz Basin during the Lower Carboniferous: 1) A transgression linked to global temperature rise in the Early Tournaisian (Middle Hastarain) resulted in the formation of thick-bedded argillaceous limestones. 2) the Hastarian–Ivorian boundary glaciation phase, 3) Upper Ivorian–Lower Viséan? tectonic block faulting. 4) the Viséan- Serpukhovian glaciation phase. The three foraminiferal assemblages encountered in the Tournaisian interval of the Mobarak Formation are restricted to specific periods within the Ivorian. The occurrence of specific foraminiferal taxa in Alborz is tightly governed by transgressions and migration of North Paleo–Tethyan biotic elements as response to the thermal period. We also combined proxies for ambient paleothermometry in addition to the indications for arid conditions and arid conditions and the presence of foraminiferal taxa with a North Paleo-Tethyan affinity in the Lower Carboniferous Mobarak Formation to suggest a paleo-position for the Alborz Basin at lower latitudes than approximately 45  –50  southern paleolatitude reported thus far. Magnetic susceptibility ( in ) was measured and compared with facies from the same sample. There is a clear link between  in and facies, and the average  in values are higher for distal facies than for proximal ones. The  in profile of Lower Carboniferous carbonate sequence reflects stratigraphic variations in response to relative sea level changes and detrital input. In the context of the sequence stratigraphic framework, the average  in values for lowstand and transgressive system tracts deposits are higher than for the highstand system tracts deposits. The clear link between  in and facies points to at least partly preserved primary  in signal, related to detrital inputs. In respect to the hysteresis measurements the in signal is mainly carried by low coercivity ferromagnetic minerals such as magnetite, with a mixture of relatively coarse grains (detrital fraction) and ultra-fine grains (probably formed during diagenesis). [less ▲]

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See detailCoating of crystallized Yttrium Orthoferrite (o-YFeO3) by wet deposition methods
Stevens, Frédéric ULg

Doctoral thesis (2016)

L’objectif de cette thèse est d’obtenir un dépôt d’orthoferrite d’yttrium orthorhombique sur substrat conducteur. Ceci, en vue de d’étudier de nouveaux catalyseurs potentiels pour le clivage ... [more ▼]

L’objectif de cette thèse est d’obtenir un dépôt d’orthoferrite d’yttrium orthorhombique sur substrat conducteur. Ceci, en vue de d’étudier de nouveaux catalyseurs potentiels pour le clivage photoélectrochimique de l’eau. Le clivage photoélectrochomique de l’eau produit dudihydrogène et du dioxygène grâce à l’énergie solaire et un catalyseur. Le dihydrogène et le dioxygène sont les combustibles d’une réaction exothermique. Transformer l’eau en ces deux composés est donc une méthode de stockage de l’énergie. Plusieurs semiconducteurs sont étudiés comme catalyseurs pour ce clivage. Cette thèse se concentre sur l’étude de l’un d’eux : l’orthoferrite d’yttrium orthorhombique (o-YFeO3), et sur deux méthodes de dépôt de ce matériau sur substrat conducteur : la méthode de déposition par plongée (dip-coating) et la pyrolyse d’une vaporisation ultrasoniquement générée (USP). Dans un premier temps, deux méthodes de synthèse del’o-YFeO3, sous forme de poudre, ont été envisagées : l’une basée sur des chlorures de fer et d’yttrium, l’autre basée sur les nitrates de ces mêmes métaux. Les éventuels problèmes de proportion ou de précipitations successives ont été respectivement dissipés par une étude de masse et une analyse de l’évolution du pH. Ces poudres, issues des chlorures ou des nitrates, ont permis de caractériser la proportion et la pureté des phases cristallines en fonction de la température de calcination par l’étude de la diffraction des rayons X (XRD) ; de caractériser l’énergie de la bande interdite (band gap optique) par la spectroscopie de réflectance diffuse (DRS) et d’en observer leur morphologie par les microscopies électroniques à balayage (SEM) ou en transmission (TEM). Toutes ces analyses nous ont poussés à continuer notre étude en nous focalisant sur la synthèse basée sur les nitrates et d’utiliser une température de calcination de 850°C. Ensuite, ces mêmes analyses (pH, XRD, DRS) ont permis d’estimer l’influence de l’ajout de différents composés organiques en cours de synthèsesur la cristallinité, la pureté, la température de calcination et l’énergie de la bande interdite de ces poudres. Cette thèse a montré que l’additif qui améliore au maximum ces propriétés est l’acide citrique. Dans le cas des poudres, dès 450°C – soit 400°C de moins que la même synthèse sans acide citrique – l’o-YFeO3est cristallisé. Les solutions qui seront utilisées pour les méthodes dedéposition seront donc composées à partir, entre autre, de nitrate de fer, de nitrate d’yttrium et d’acide citrique. La méthode dite du « dip-coating » consiste à plonger le substrat qu’on compte recouvrir dans une solution de précurseurs – composée, entre autre, des nitrates métalliques et d’acide citrique – de le ressortir recouvert d’un film mince de cette solution pour ensuite le chauffer et ainsi obtenir un dépôt du matériau désiré. De nombreux problèmes d’adhérence, de stabilité de solution, de quantité de matière, d’homogénéité de dépôt et de cristallisation de composé ont eu raison de nos efforts pour la mise au point de tels dépôts par cette technique. L’autre méthode de déposition utilisée durant cettethèse est l’«USP ». Cette technique vaporise une solution de précurseurs au moyen de vibrations ultrasoniques. Le brouillard ainsi généré est propulsé vers le substrat par du gaz sous pression. Le substrat, pendant ce processus, est placé sur une plaque chauffante. La solution vaporisée chauffera au fur et à mesure qu’elle se rapprochera du substrat. Cette technique implique l’ajustement de plusieurs paramètres qui définissent le type de composés qui atteindront le substrat. Cette thèse a abouti à la mise au point de ces différents paramètres qui ont permis d’obtenir un dépôt d’orthoferrite d’yttrium orthorhombique sur un substrat conducteur. Ce dépôt présente une activité photoélectrochimique en tant qu’anode pour le clivage de l’eau, mais ses performances ne permettent pas, dans son état actuel, de concurrencer les semiconducteurs précédement décrit par d’autres chercheurs. Une poursuite des travaux dans ce domaine devraient se focaliser sur le dopage et/ou la structuration contrôlée de l’orthoferrite d’yttrium. [less ▲]

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See detailContribution à l'amélioration de la production laitière et de la reproduction des vaches Ankole et croisées Ankole x Frisonne en territoire de Beni, République Démocratique du Congo
Katungu Kibwana, Denise ULg

Doctoral thesis (2016)

Eastern Democratic Republic of the Congo, especially Kivu, is a large pastoral region but the cattle numbers of which considerably decreased following the conflicts that the country underwent over the ... [more ▼]

Eastern Democratic Republic of the Congo, especially Kivu, is a large pastoral region but the cattle numbers of which considerably decreased following the conflicts that the country underwent over the past two decades, with important losses in breeding skills. Cattle breeding currently practiced in Kivu may be described as "great unknown". Data available in literature relate to old studies and focuse on peripheral areas from Kivu. This study aimed, at first, to establish a diagnosis on dairy cattle breeding inhabits in the east of the Democratic Republic of the Congo, especially in the provinces of North Kivu. This diagnosis based on the choices adopted by breeders according to animal genetic, constraints related to feeding, animal housing and the main reproductive characteristics of females. The other objective of the study was to test an improved farming method taking into account the perceived constraints highlighted with the diagnostic investigation. The proposal took into account the realities of the south, and thus was characterized by simplicity and speed of implementation, in the emergency context that the population lives daily in the region. 1. Breeding cattle and milk production in tropical environments: Case of eastern region of the Democratic Republic of the Congo. Inventory and perspectives. In East of Democratic Republic of the Congo, cattle breeding is based on exploitation of non-selected dairy cattle raised in extensive unimproved rearing system. Extensive breeding of traditional type is the bulk of the pastoral activities in the region and the country. The main factors limiting cattle breeding in this area of D.R. of the Congo, as in most tropical environments, consist in: (i) low genetic potential of African cattle with low level of production and (ii) poor farming conditions due to low feed quality and health coverage, precarious livestock housing, poor management of reproduction and animal genetic resources, and low breeders’ technicity. These factors affect productive and reproductive performance of animals. Low milk production arising does not allow breeders to provide their needs and cover milk needs of the population, thus leading to importation of large amounts of milk and its derived products. 2. Extensive farming practices and cattle performances of the local breed and crossed with exotic dairy breeds in the Democratic Republic of the Congo The study was conducted in Beni, Democratic Republic of the Congo. It aimed to highlight the breeding cattle system and dairy production levels of both local cows and cows crossed with exotic dairy breeds raised in the environment, and reproductive parameters (age at first calving, interval calving and fertility) as well as mortality rate of animals. The data, obtained from 8464 animals, including 4805 cows (2309 local vs 2496 crossed with Sahiwal and exotic dairy breeds - Friesian, Brown Swiss and Jersey considered ameliorative) were analyzed by chi-square test for categorical data, by generalized linear model based on the genetic type, forage quality and type of supplementation for continuous data, and by Anova-One-way for to test the effect of the degree of specialization and professionalism of breeders. Non-parametric data were analyzed by Spearman correlation test. All factors studied had a significant influence on milk production (P <0.001); calving interval, meanwhile, was significantly influenced by breed (P <0.002) and the type of supplementation (P= 0.011), age at first calving was only influenced by the breed (P <0.001). Milk production, age at first calving, calving interval, fecundity rate and mortality rates of local cattle were respectively 2.6 ± 0.17 l/d, 41.1 ± 1.02 mo, 22.6 ± 0.73 mo, 53.0% and 4.8% between 0 and 1 year and 3.6% between 1 and 2 years vs 6.1 ± 0.21 l/d, 32.5 ± 1.21 mo, 19.1 ± 0.87 mo, 44.8%, 6.7% between 0 and 1 year and 4.4% between 1 and 2 years, respectively, in crossed type. Forage supplementation had a significant effect on milk production compared to the situation with natural forage (1.6 l/d more, P <0.001), and by-products supplementation associated or not to mineral permitted an increase of 0.9 liter of milk production compared to the situation without supplementation (P= 0.041). Increased supplementation with or without the mineral reduced calving interval by 3.6 mo compared to the situation without supplementation, and by 2.5 mo compared to the simple supplementation (P= 0.011). The type of forage had no significant effect on calving interval. The mortality rate was significantly influenced by breed (P= 0.017). A significant interaction between the genetic type and forage type was observed on milk production (P <0.001). Some parameters studied were also influenced by degree of specialization of the breeders - calving interval (P= 0.04 in crossbred type and P <0.001 in local bred) - age of first calving in local bred (P= 0.015); and by degree of professionalization - age of first calving in local bred (P= 0.04) - calving interval (P= 0.08) and milk production in crossbred type (P= 0.04). 3. Effect of improved feeding and housing, and of Friesian blood level on milk production of Ankole x Friesian crossbred cows The study was carried out at the Vitolu/Misugho farm extension, in Beni territory, Democratic Republic of Congo. The objective of this study was to quantify the effects of rearing conditions (feeding and housing in stall of night), and of Friesian blood level on milk production of Ankole x Friesian crossbreds cows. Data were obtained from 30 cows. The birth weights of calves were compared between groups using a Student test. Using the SAS software (Statistical Analysis System, version 9.1.3), data on average daily milk production were analyzed using a mixed model (proc mixed), including the effects of treatment group, Friesian blood level, day in milk, and the simple interactions between these effects. Day in milk within animal was included as a repeated measurement, and a type 1 autoregressive covariance structure was associated to. Differences were considered significant at P <0.05. The indicators of variation were expressed as standard deviation. The experimental unit was the cow. All factors affected significantly daily milk production (P <0.001). The results of these analyzes show that average milk production was higher group offered the improved feed and housed in the stable (6.8 ± 0.31 l/d vs 5.2 ± 0.31 l/d in the control group cows housed in kraal at night, P <0.001). The pic of milk production was observed around the 79th and 96th days respectively in IG and CoG. In both groups, cows adapted their milk production for the rainfall regime and milk production was significantly higher during the rainy season. Lactation curve was very dependent on rainfall regime and did not follow the shape of a normal curve. Improved milk production and highest values were observed with >25% of Friesian blood level (5.3 ± 0.31 l/d to 6.6 ± 0.23 l/d, from 25 to 44%, P <0.001). Interactions between treatment (improved feed and housing) and Friesian blood level were also observed (P <0.001). The IG cows showed the highest milk production compared to the control group (milk productions of 5.8 ± 0.50; 7.0 ± 0.66 and 7.8 ± 0.70 l/d were obtained with 25, 38 and 44% of blood Friesian, respectively, in the treated group vs. 4.8 ± 0.23; 5.5 ± 0.23 and 5.4 ± 0.16 l/d in the control group, P <0.001). [less ▲]

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See detailDynamique des flux de carbone entre l'atmosphère et des écosystèmes ouest-africains: cas des forêts et savanes sous climat soudanien au Bénin
Ago, Expédit Evariste ULg

Doctoral thesis (2016)

In West Africa as elsewhere in other parts of the world, natural and anthropogenic ecosystems are the main sources for energy, building poles and livestock fodder. They probably behave like some nets ... [more ▼]

In West Africa as elsewhere in other parts of the world, natural and anthropogenic ecosystems are the main sources for energy, building poles and livestock fodder. They probably behave like some nets carbon sinks, but there are only few studies that have focused on their carbon exchanges with the atmosphere. Preserving terrestrial ecosystems has proven essential to any emissions mitigation policy of green house gases, notably CO2. This thesis focuses on the analysis of the CO2 fluxes in three contrasting types of the ecosystem under a Sudanian climate in Benin. Specifically, it was a cultivated forest, a protected forest and a cultivated savannah. Turbulent CO2 fluxes were measured by an eddy-covariance system placed above the ecosystems. The measurements were made during variable periods of 17 months (cultivated forest), 18 months (protected forest) and 29 months (cultivated savannah). The three studied sites have been equipped by the hydro-meteorological observatory AMMA-CATCH and the national project Ouémé 2025. The CO2 fluxes data were completed by some meteorological measurements and by an inventory of dominating species the three sites. Fluxes were examined on the basis of the two main seasons imposed by the cycle of West African Monsoon. The spatial (local and regional) and temporal (hour, seasonal, annual and inter-annual) scales were considered according to the sites. Water was the main factor controlling the dynamic of the terrestrial West African ecosystems. At the daily scales, the radiation was the main driving variable of the net CO2 fluxes. Besides that radiation control, a clear relationship was observed between the net CO2 fluxes and the canopy conductance. A limited impact of saturation deficit was observed, notably during the afternoon. The soil moisture was the main factor governing the ecosystem respiration. However, no clear dependency of the ecosystem respiration on the temperature was observed at hourly scale. After long dry periods, the ecosystem respiration increased immediately in response to the first significant rains. The CO2 fluxes and the characteristics of the protected forest were always higher than those of the cultivated savannah at the daily and seasonal scales. At the annual scale, while the protected forest (Bellefoungou) and cultivated savannah (Nalohou) sequestered an average of 640 ± 50 and 232 ± 27 g C m-2, respectively considering the period of the measurements, the cultivated forest was in equilibrium with 29 ± 16 g C m-2. Overall, the three studied ecosystems were more efficient during morning and wet season than during afternoon and dry season. Finally, this study revealed that the inter-annual variability of the carbon sequestration by the cultivated savannah was mainly controlled by the ecosystem respiration variability in relation to the soil water content variation. [less ▲]

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See detailDe la magie au magique. Conscience, réalité-humaine et être-dans-le-monde chez Sartre (1927-1948)
Dassonneville, Gautier ULg

Doctoral thesis (2016)

This research deals with Sartre's early existential philosophy by resituating it in the field of French post-Comtian philosophy in the early twentieth century and by re-establishing an anthropological ... [more ▼]

This research deals with Sartre's early existential philosophy by resituating it in the field of French post-Comtian philosophy in the early twentieth century and by re-establishing an anthropological moment in which the issue of magic is explored in the psychological and social sciences. Following the different paths of the conceptual exchange through which the notion of magic becomes that the magical in Sartre's view, we study three poles of sartrian phenomenological ontology : intentional consciousness, human reality and being-in-the-world. The hypothesis advanced by this thesis is that the magical, according to different modes ranging from topicalization through obliteration, plays a determining role in the elaboration of existentialism whose genesis is traced here from Sartre's very first writings in 1927.  Faced with the legacy of a positivist anthropology in terms of an analytical methodology, Sartre privileges a synthetic approach and conceives consciousness in its affective and irrational aspects. Images of magical thought are called upon for rethinking openness to the world of consciousness and its relationship to itself and to Others. Returning to Sartrian anthropology, we question how consciousness can be grasped as an irreflexive and absolute spontaneity and how human reality is interpreted through its attitudes and behaviours; in particular through the way it faces its own freedom which is fundamentally and irremediably exposed to contradiction. This structure of human reality as existential project leads Sartre to reconsider being-in-the-world as based in originary dispossession through which ontology is brought back to the magical. [less ▲]

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See detailAspects socio-économiques et technique de la conservation du mouton Koundoum au Niger
Hamadou, Issa ULg

Doctoral thesis (2016)

Résumé Le mouton Koundoum représente le principal mouton à laine du Niger et est exclusivement élevé dans les îles et sur les bords du fleuve Niger, depuis la frontière du Mali jusqu’à Niamey. Il ... [more ▼]

Résumé Le mouton Koundoum représente le principal mouton à laine du Niger et est exclusivement élevé dans les îles et sur les bords du fleuve Niger, depuis la frontière du Mali jusqu’à Niamey. Il constitue une source de nourriture et de revenus pour les agriculteurs ruraux de cette zone. Cette race est reconnue pour sa production de laine et sa remarquable adaptation à l’humidité dans la vallée du fleuve Niger. Peu d’informations sont disponibles sur les caractéristiques de cette race alors qu’on assiste à une régression drastique de son effectif. La documentation des caractéristiques d’une race est importante pour son utilisation et sa conservation. Cette étude a été entreprise pour documenter (i) le système de production et les caractéristiques morphobiométriques du mouton Koundoum, (ii) les préférences des éleveurs et leur disposition à payer ou à recevoir une compensation pour les caractéristiques des ovins, (iii) les caractéristiques de reproduction du mouton Koundoum et (iv) les points de vue des parties prenantes potentielles susceptibles de contribuer à la réussite de la gestion et la conservation de la biodiversité des animaux d'élevage au Niger. Ainsi, pour caractériser la race et comprendre son contexte de production, une enquête a été menée auprès de 104 ménages dans quatre communes le long du fleuve Niger (Kollo, Tillabéry, Say et Tera) pendant la période d’août à décembre 2011. Neuf mesures corporelles, comprenant le poids vif, ont été prises sur 180 moutons Koundoum (101 femelles et 79 mâles). L’effectif des troupeaux de moutons varie de 2 à 60 têtes, avec une taille moyenne de huit animaux et les deux tiers des troupeaux comptant moins de 10 animaux. Principalement alimentés sur les pâturages naturels, 85,6% des troupeaux reçoivent des résidus de récolte en supplément. Seul l'accouplement naturel est pratiqué par les éleveurs et les soins vétérinaires sont limités aux anti-helminthiques et à une pharmacopée traditionnelle. L'affiliation fréquente des éleveurs à des associations professionnelles apparait comme un facteur favorable à la mise en œuvre d'un programme collectif de conservation. Le mouton Koundoum est de robe blanche ou noire, avec une fréquence plus élevée pour la couleur noire (75,6%). Les pendeloques sont présentes dans les deux sexes à des fréquences similaires, d’environ 14 %. Toutes les variables biométriques sont positivement et significativement corrélées entre elles. Le périmètre thoracique montre la meilleure corrélation avec le poids vif, tant chez les mâles que chez les femelles. Trois variables ont été sélectionnées pour la prédiction du poids vif: le périmètre thoracique, la hauteur au garrot et la longueur de la croupe. Il ressort de cette étude que la conservation in situ de la race Koundoum s’annonce comme très problématique, du fait du manque d’opportunités de marché pour la laine et de disposition des petits éleveurs à élever le mouton Koundoum en race pure. Dans le but d’objectiver ce dernier frein, la seconde étude, conduite dans la même zone de septembre 2012 à février 2013, caractérise les préférences des éleveurs pour les béliers reproducteurs et aborde leur disposition à contribuer au programme de conservation du mouton Koundoum à travers leur appréciation quantifiée des principales caractéristiques phénotypiques de la race. L'outil de l'empilement proportionnel est utilisé d'abord dans 11 groupes de discussion focalisée réunissant des éleveurs autour de la question des principaux critères de sélection de béliers reproducteurs. La méthode d'analyse conjointe multi-attributs est ensuite appliquée avec 168 propriétaires de moutons. L'estimation économétrique de la fonction d'utilité des éleveurs est réalisée avec un modèle logit conditionnel et la disposition à payer est calculée par le rapport entre chaque coefficient d’utilité des caractères et de l’attribut monétaire. Les résultats révèlent un fort rejet par les éleveurs des caractéristiques comme la laine et la robe noire et montre ainsi la faible acceptabilité d'un programme de conservation in situ. Quelques éleveurs avec une préoccupation particulière pour la conservation de la race, pour des motifs culturels, peuvent néanmoins adhérer à un tel programme de conservation, qui devrait être principalement fondé sur des stratégies ex situ. En vue de ces stratégies ex situ, il est nécessaire d’étudier les caractéristiques de reproduction chez le mouton Koundoum. La troisième étude a ainsi été conduite en station, à la ferme expérimentale et de recherche de la Faculté d’Agronomie de l’Université Abdou Moumouni de Niamey (Niger) pendant la période de décembre 2013 à avril 2014. L’étude a plus précisément déterminé les caractéristiques du cycle œstral de la brebis et quelques caractéristiques spermatiques du bélier de la race Koundoum du Niger. Ainsi, seize brebis et huit béliers Koundoum ont été utilisés pour cette étude. Les brebis ont été soumises à une observation biquotidienne de leur comportement sexuel en vue de détecter les œstrus, à l’aide de béliers boute-en-train. Les échantillons de sperme ont été recueillis à l’aide d’un vagin artificiel chez les béliers pendant les périodes d’œstrus des brebis. La motilité du sperme a été déterminée à l’aide d’un microscope et sa concentration à l’aide d’un spectrophotomètre. Sur les 16 brebis, 13 ont manifesté au moins une fois des comportements d’œstrus ayant une durée moyenne de 37,8 ± 5,8 heures avec une durée moyenne de cycle œstral de 18,1 ± 1,1 jours. La collecte de semence a pu être réalisée sur 4 béliers sur les 8 inclus dans le protocole. Les éjaculats collectés ont présenté un volume moyen de 1,03 ± 0,3 ml, une motilité de 3,4, et une concentration de 1322 ± 544 millions/ ml. La connaissance de la durée du cycle et de l’œstrus est un élément de base pour la maîtrise de la fonction sexuelle des brebis. La difficulté de collecte de la semence de béliers Koundoum devra être prise en compte dans les plans de conservation par cryogénisation de paillettes. Les informations obtenues à travers cette étude sont une base permettant de poser les premiers jalons du programme de conservation et d’amélioration de cette race. Enfin, une quatrième et dernière étude a été conduite de mars à avril 2014 pour examiner les points de vue des parties prenantes potentielles susceptibles de contribuer à la réussite de la gestion et la conservation de la biodiversité des animaux d'élevage au Niger. La recherche applique la méthodologie Q afin de révéler des discours consensuels et divergents. Après le développement de l'ensemble des affirmations sur le thème de la biodiversité (échantillon Q), les arrangements des affirmations ont été réalisées par les répondants à travers une échelle de Likert à 7 niveaux, de -3 à +3. L'analyse des données (les arrangements Q) avec le package qmethod sous le logiciel R a révélé trois points de vue distincts des parties prenantes sur l'importance de la biodiversité dans l'agriculture et l'élevage, l'équilibre entre le progrès et la conservation et les différentes méthodes de conservation. L'étude montre un consensus apparent sur l'importance de la biodiversité, qui est évidemment un sujet promu dans le pays. Derrière le consensus, différents discours sont définis qui semblent tous divisés par le même dilemme entre la conservation et le développement économique. Comprendre les différentes réponses et poids attribués à chacun des composants du dilemme guidera des campagnes de sensibilisation et aidera à identifier les intérêts divergents des parties prenantes. [less ▲]

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See detailAerothermodynamics of Pre-Flight and In-Flight Testing Methodologies for Atmospheric Entry Probes
Sakraker, Isil ULg

Doctoral thesis (2016)

Spacecraft, returning back to Earth, experience a very harsh environment during the encounter with the particles of the atmosphere. One of the major issues of the atmospheric entry is the extreme ... [more ▼]

Spacecraft, returning back to Earth, experience a very harsh environment during the encounter with the particles of the atmosphere. One of the major issues of the atmospheric entry is the extreme aerodynamic heating and the exothermic chemical reactions due to the gas-surface interaction at hypersonic free stream velocities. There is a constant effort by the space agencies to increase the understanding of the re-entry flight dynamics to optimize the spacecraft and especially its thermal protection system design. During the design process, ground tests and numerical tools are extensively used for their low cost and controlled environment abilities. However, real flight tests are indispensable for ground test and numerical tools validation. Due to high costs, such missions are rarely launched and thus there is an increasing interest in small affordable entry probes. Such platforms, once matured enough, may serve as an easily accessible tool to produce experimental data. It is the aim of this dissertation to propose tools to improve ground test capabilities and on the other hand to present the design, and using the developed tools, the testing of aerothermodynamic experimental payloads to collect flight data with a small entry probe. QARMAN (QubeSat for Aerothermodynamic Research and Measurements on AblatioN) is a triple unit CubeSat with ablative and ceramic thermal protection systems. It will perform an atmospheric entry with 7.7 km/s and a peak heat flux of 1.7 MW/m2. The aim of the in-flight experiments is to retrieve real flight data on ablator efficiency (temperature, pressure, recession) and temperature-pressure measurements for transition on the side panels. The peculiar squared geometry of QARMAN led to the development of a Flight-to-Ground Duplication methodology accounting for spacecraft geometries. It allows duplicating fully the stagnation region of a spacecraft with an arbitrary geometry in subsonic plasma wind tunnels. As a requirement of this methodology, free stream characterization techniques, specifically enthalpy measurement techniques are introduced. Experimental and numerical databases are built. A thorough ablation characterization campaign in VKI Plasmatron is conducted to provide input for building material response models. The cork P50 ablator is studied in terms of surface and sub-surface temperatures, emissivity, mass loss, char-pyrolysis layers, outgassing species and recession and swelling profiles. Similar in-flight experiments are proposed for QARMAN flight for in-depth temperature and pressure. Methods to build models for advanced data treatment are proposed. A full picture of post-flight analysis strategy is described for each study to relate the ground tools and flight data. [less ▲]

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See detailExperimental and Numerical Characterization of Damage and Application to Incremental Forming
Guzmán Inostroza, Carlos Felipe ULg

Doctoral thesis (2016)

Nowadays, product manufacturing can be divided into two groups: relatively simple products produced in a large production chain and complex (specialized) components produced in reduced batches. Within the ... [more ▼]

Nowadays, product manufacturing can be divided into two groups: relatively simple products produced in a large production chain and complex (specialized) components produced in reduced batches. Within the second group, prototyping through incremental sheet forming (ISF) has been subject of several studies. ISF refers to processes where the plastic deformation occurs by repeated contact with a relatively small tool. A crucial aspect in the ISF processes is that the final shape is determined only by the tool movement. The focus of this research is the single point incremental forming (SPIF) process variant, where a clamped sheet metal is deformed by using a relatively small spherical tool. SPIF has several advantages over traditional forming, such as the high formability attainable by the material. Different hypothesis haven been proposed to explain this behavior, but there is still not a clear and definitive understanding of the relation between the particular stress and strain state induced in the material during SPIF and the material degradation leading to localization or fracture. In this thesis, a fundamental research is proposed using the finite element (FE) code LAGAMINE, developed within the University of Liège. Numerical implementation and validation of the Gurson-Tvergaard-Needleman (GTN) damage model into this FE code is performed. An experimental test campaign is developed to characterize plastic and damage behavior and to validate the damage model for the DC01 steel grade. Finally, this damage model is applied to simulate the SPIF process in order to verify if it is capable to predict failure. The thesis discusses the material parameter identification for classical plasticity models, describing the anisotropy and hardening behavior of the sheet metal. The derivation of the equations of the numerical damage model and the efficiency of the implementation is presented in great detail. A methodology for the numerical parameter identification of the damage model is proposed, including microscopic measurements by optical microscopy and strain and displacement field measurements by digital image correlation (DIC). The identified Gurson model is applied to simulate standard SPIF geometries, like the line, cone and pyramid tests. The simulations are performed using the solid-shell element formulation and validated in terms of shape and force prediction. Literature reviews of the Gurson model and the SPIF process are also included. The experimental results show that the selected material (DC01 steel sheet) exhibits a slight anisotropic behavior and work-hardening stagnation on cyclic tests. The performed microscopic measurements are not representative of the actual damage, but they give a qualitative estimation of the physical mechanism of fracture. The initial porosity of the material was determined using optical microscopy measurements in the base material. The numerical implementation of the model is developed with all variables integrated in an implicit way, based on the backward Euler scheme. Nucleation, coalescence and shear extensions implementations are validated by results obtained from the literature. The macroscopic campaign allowed to identify the parameters for nucleation, coalescence and shear. An unique set of results matching all experiments was not possible to obtain, so different sets of parameters are retrieved following an approach that includes inverse modeling and sensitivity analysis. A numerical-experimental comparison of strain values in the loading direction shows that the model is able to correctly predict the strain distribution except during localization of the strain. Globally, the obtained set of material parameters is in good agreement with the experimental results. For SPIF FE simulations, the results of the shape prediction are in good agreement with the experimental results, both for the line and pyramid test. Nevertheless, the force prediction is too high compared to reference values. On the other hand, the GTN model is capable to detect failure in a pyramid and a cone, but the prediction is too premature compared to the experimental failure angle for the same material and geometry. An accurate prediction of failure for the SPIF process was not possible to achieve. The GTN model extended to shear presents inherent flaws that prevent an accurate prediction of the failure angle for the SPIF process. Hence, an extensive research on the damage mechanisms leading to fracture for SPIF cannot rely (only) on the GTN model. The classical coalescence model of the GTN model is insufficient to correctly predict failure. Hence, it is recommended that further analysis concentrates on the description of this particular stage of damage evolution. During the development of this thesis, a robust implementation of the GTN model into the FE code LAGAMINE was done, including an extensive experimental database of microscopic and macroscopic measurements for the DC01 steel sheet. Other phenomena can be explored thanks to this model. [less ▲]

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See detailCo-simulation of Electromagnetic Transients and Phasor Models of Electric Power Systems
Plumier, Frédéric ULg

Doctoral thesis (2016)

This study investigates and improves methods used for the combination of phasor and electromagnetic transients time domain simulations of power systems. It involves the study of the protocols of ... [more ▼]

This study investigates and improves methods used for the combination of phasor and electromagnetic transients time domain simulations of power systems. It involves the study of the protocols of computation, the comparison of the different kinds of boundary conditions used to represent one sub-system when simulating the other, and the interfacing of phasor and electromagnetic transients models. The Nordic system has been used to realize the tests. Illustrative simulation results are reported for the case of a single and of multiple boundary buses between the sub-systems. [less ▲]

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See detailEfficient methods for large-scale time-harmonic wave simulations
Marsic, Nicolas ULg

Doctoral thesis (2016)

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See detailCARRIÈRES MIGRATOIRES ET POLITIQUE D’INTÉGRATION DANS LA RÉGION DE MADRID. L’EXEMPLE DES MIGRANTS ADULTES DANS LA VILLE DE PARLA (2007-2012)
Brey, Elisa ULg

Doctoral thesis (2016)

This dissertation analyses the migratory carreers of adult migrants settled in the urban outskirts of Madrid, in Spain, during the first years of the economic crisis (2007-2012). The aim is to understand ... [more ▼]

This dissertation analyses the migratory carreers of adult migrants settled in the urban outskirts of Madrid, in Spain, during the first years of the economic crisis (2007-2012). The aim is to understand the dynamics of migratory carreers through the access to a residence permit, the labour and the housing market. To achieve this goal, semi-structured interviews have been conducted with migrants from Morocco, Romania, countries of Subsaharan Africa and the Andean Community (Ecuador, Colombia, Bolivia and Peru). Interviews and observations have also been conducted with leaders of local associations and representatives of municipal services to which migrants have access. A typology is proposed, considering that migratory carreers can adopt regular or informal dynamics, following the characteristics of a community or a society. [less ▲]

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See detailBeyond the Line: Murray Bail's Spatial Poetics
Herbillon, Marie ULg

Doctoral thesis (2016)

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See detailLa justice pénale internationale à l'épreuve des droits humains : étude de la privation de liberté devant la Cour pénale internationale
Deprez, Christophe ULg

Doctoral thesis (2016)

Entre instrument de protection des libertés fondamentales et menace à l'égard de ces mêmes libertés, l'activité pénale est un phénomène cerné de paradoxes. Les règles de protection des droits humains ont ... [more ▼]

Entre instrument de protection des libertés fondamentales et menace à l'égard de ces mêmes libertés, l'activité pénale est un phénomène cerné de paradoxes. Les règles de protection des droits humains ont notamment pour ambition de contenir ces paradoxes : en encadrant le pouvoir de contrainte que l'autorité répressive peut exercer sur les individus, ces normes essentielles doivent permettre de garantir une justice pénale qui demeure fidèle aux principes qu'elle entend défendre. Mais quelle peut bien être l'emprise des droits humains sur l'action du juge pénal international ? Dès lors que le droit international des droits de l'homme a été pensé et conçu pour circonscrire l'autorité des États, qu'en reste-t-il lorsqu'on cherche à l'appliquer – en particulier – à la Cour pénale internationale ? Dans quelle mesure et sur la base de quel(s) fondement(s) juridique(s) cet acteur répressif d'un genre nouveau est-il tenu au respect de règles auxquelles il n'a pas expressément souscrit ? Les spécificités de la justice pénale internationale – et, singulièrement, la gravité des crimes ayant favorisé son émergence – réclament-elles une adaptation du niveau de protection accordé aux suspects et accusés internationaux ? Quel accueil le Statut de la Cour pénale internationale et les règlements qui l'accompagnent réservent-ils aux standards pertinents, en particulier en matière de privation de liberté ? La jurisprudence de la Cour révèle-t-elle une pratique conforme à ces standards ? Le projet de recherche vise à apporter un éclairage sur l'ensemble de ces questions et, ainsi, à mettre la justice pénale internationale à l'épreuve des droits humains. [less ▲]

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See detailDiagnostic préalable à un contrat d'axe sur la ligne SNCB 40 Liège-Guillemins - Visé. Etude du potentiel de l'outil contrat d'axe en Wallonie et de la densification des gares de la ligne 40
Wilmotte, Pierre-François ULg

Master's dissertation (2016)

Le travail vise à alimenter la réflexion menée par le consortium Pluris - Trame - B. Bianchet à propos de l'élaboration d'un Schéma de Développement Territorial (SDT) pour l'arrondissement de Liège : d ... [more ▼]

Le travail vise à alimenter la réflexion menée par le consortium Pluris - Trame - B. Bianchet à propos de l'élaboration d'un Schéma de Développement Territorial (SDT) pour l'arrondissement de Liège : d'une part, étudier le potentiel des quartiers de gare en région liégeoise et, d'autre part, à voir si l'outil des "Contrats d'axe", développés en France, pourrait être pertinent dans le cadre wallon. La recherche a été appliquée à un axe ferroviaire de la région de Liège. [less ▲]

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See detailStimuli-responsive self-assembled macromolecular systems with potential drug delivery applications: structural characterization by Small-Angle Neutron Scattering
Joset, Arnaud ULg

Doctoral thesis (2016)

Colloids are known since the early 19th century but they have mainly sparked interest since the last few decades thanks to their use in biomedical applications or in the design of new materials. The aim ... [more ▼]

Colloids are known since the early 19th century but they have mainly sparked interest since the last few decades thanks to their use in biomedical applications or in the design of new materials. The aim of this thesis is the study of stimuli-responsive colloids by Small-Angle Neutron Scattering (SANS). The stimuli may be the pH, the temperature, the addition of a ligand or of metallic ions or a combination of them. SANS is a useful technique which provides information about the internal structure of nano-objects but also, if appropriate conditions are met, about the organization of the objects in solution. Several samples built from the auto-assembly of block copolymers and liposomes have been prepared. The macroscopic cross sections have been modeled with the aim to infer the main structural parameters of the samples: the global size, the polydispersity, the structure and volume occupied by the hydrophilic and hydrophobic components inside the nano-objects. The SANS measurements have been performed as a function of the intensity of the stimulus, in order to quantify the evolution of the structural parameters. The first experimental part focuses on micellar samples built from sequenced block copolymers. The blocks may be biodegradable (e.g., poly(ε-caprolactone)), biocompatible (e.g., poly(ethylene oxide)), pH-sensitive (e.g., poly(2 vinylpyridine), poly(acrylic acid)) or temperature-sensitive (e.g., poly(N-isopropylacrylamide)). The influence of the concentration and the formation of bridges between micelles have been investigated through the analysis of metallo-supramolecular micellar gels resulting from the self-assembling of polystyrene-block-poly(tert-butylacrylate) PS-b-PtBA-tpy (tpy stands for terpyridine) block copolymers in the presence of transition metal ions. The second part focuses on the analysis of liposomes interacting with an increasing concentration of Randomly Methylated β-cyclodextrins (RAMEB). This part is divided into two chapters. The first one deals with liposomes mainly composed of dimyristoylphosphatidylcholine (DMPC) and the second one investigates the effects of cholesterol doping on the same DMPC liposomes interacting with RAMEB. [less ▲]

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See detailLa disponibilité et le prix du foncier à vocation économique: quel impact sur le développement économique en Wallonie?
Vandermeer, Marie-Caroline ULg

Doctoral thesis (2016)

This doctoral dissertation concerns the policy of land production related to economic land in Wallonia. This policy corresponds to the development of economic estates by public authorities, through ... [more ▼]

This doctoral dissertation concerns the policy of land production related to economic land in Wallonia. This policy corresponds to the development of economic estates by public authorities, through economic development agencies, to accommodate businesses. It is based on the argument according to which the availability of land – cheap if possible – is an essential factor in territorial attractiveness and competitiveness. The reflections presented in this dissertation originate from the discrepancy between this argument and the scientific literature devoted to regional development. Indeed, unlike elected representatives and economic development agencies, scholars active in the field of regional sciences only very rarely refer to the impact of the land markets on levels of development. Rather than focusing on the theme of land prices and land availability, regional scientists underline the importance of intangible factors such as innovation, education, integration into networks, territorial identity, strategic management or governance. In view of this difference, it seems appropriate to assess the spatial and economic effectiveness of the Walloon policy of land production. To do this, our wish is to objectify the real role of the availability and the price of economic land on territorial development. The first part of the dissertation develops a reflection on the literature dedicated to the relationships between land and property markets and regional development. It leads to highlight the need to develop knowledge on the impact of land and property markets on business competitiveness, regional attractiveness and economic development. The second part is devoted to the study of the availability of economic land and aims to assess the spatial effectiveness and the economic effectiveness of policies which offer an important quantity of economic land. To do this, statistical analyses were conducted on two study areas: the Northwest Europe and Belgium. As regards spatial effectiveness, the results underline significant national differentials in terms of land consumption on the one hand, while highlighting the economic sprawl that characterises France and Belgium on the other hand. As regards economic effectiveness, our results show that the impact of the development of economic estates on growth depends largely on regional contexts. Our analyses identified three regional profiles. First, urban regions, where land availability only plays a marginal role, most likely owing to the presence of numerous activities that are not very extensive spatially, yet very productive in terms of added value. Secondly, intermediate regions, where the availability of economic land has a real impact on development. However, it would appear that the profile of these regions is adapted to the presence of activities which, like logistics, generate a limited amount of jobs and added value per surface unit. Thirdly, rural regions, where the opening of land to urbanisation does not deliver the desired results. In these regions, the availability of land is not a sufficient condition for economic growth and job creation. However, we have to precise that the Belgian rural regions are rather similar to intermediate regions, probably thanks to their good connectivity. The third part concerns the study of the economic land prices. It tends to assess the impact of these prices on company property costs. The developed statistical analysis is based on annual accounts of companies with one reporting unit localised in Walloon economic estates. Results suggest that property costs are rather low. On average, they represent 1.4% of all their operational costs and 5.4% of their added-values. By contrast, labour costs are eight times higher. In addition, our analyses suggest that an increase in land prices would have a limited impact on property costs. These results tend to invalidate the hypothesis that low land prices are a key determinant of regional development. Although, property costs are highly dependent on the business sector and the size of firms. For instance, for logistic companies and small firms, property costs represent more than 10% of their added-values and 2% to 5% of their operational costs. These results tend to highlight the fact that high land prices can have a negative impact on the development of these companies. As a final point, our conclusion discusses the recommendation that economic land supply policies must be adapted according to both, the profile of the territories and the profile of the firms. Indeed, in urban regions, land supply policies aiming to supply an important land supply at low price is probably inefficient from an economic standpoint. By contrast, economic development can be expected in intermediate regions with active land policies dedicated to land-intensive activities. Moreover, a specific attention should be paid to small companies. [less ▲]

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See detailÉtude des anthocyanes de l’Hibiscus sp
Beye, Cheikh ULg

Doctoral thesis (2016)

Très répandues dans le règne végétal, les anthocyanes sont le sujet d'un grand nombre d'études. Celles-ci abordent en général les aspects concernant leur instabilité vis-à-vis des conditions dans ... [more ▼]

Très répandues dans le règne végétal, les anthocyanes sont le sujet d'un grand nombre d'études. Celles-ci abordent en général les aspects concernant leur instabilité vis-à-vis des conditions dans lesquelles elles sont employées ou l'effet bénéfique de leur consommation sur certaines pathologies chroniques. Provenant de nombreux types de fruits et légumes comestibles, elles sont extraites en vue de leur utilisation comme colorant alimentaire naturel. C'est ce dernier aspect qui a été le sujet principal de ce travail dont l'objectif était de montrer que les calices d’Hibiscus sabdariffa (H. sabdariffa) pouvaient être utilisés comme matière première pour la fabrication de colorant. Les deux principaux cultivars provenant du Sénégal présentent des différences significatives du point de vue de leur contenu en anthocyanes sur le plan qualitatif et quantitatif. L'influence des conditions de culture sur la concentration en anthocyanes a été mise en évidence. Une technique chromatographique a été utilisée pour concentrer les anthocyanes. Les résultats provenant d'expériences faites en batch agité avec une résine macroporeuse ont permis de déterminer les paramètres tels que le temps de contact nécessaire à l'atteinte de l'équilibre, la capacité d'adsorption maximale et de conclure que la résine utilisée avait une capacité d'adsorption élevée pour les anthocyanes. Suite à la fabrication du colorant, une partie importante de la masse de calices restait inutilisée alors qu'elle contenait encore des substances valorisables. Leur caractérisation a permis de montrer que les résidus des calices d'H. sabdariffa pourraient être valorisés par la production de pectines destinées au marché des additifs alimentaires, d'oligosaccharides à effet prébiotique ou de biocarburants. [less ▲]

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See detailPerformance and Robustness of Nonlinear Systems Using Bifurcation Analysis
Detroux, Thibaut ULg

Doctoral thesis (2016)

Nonlinear vibrations can be frequently encountered in engineering applications, and take their origin from different sources including contact, friction or large displacements. Other manifestations of ... [more ▼]

Nonlinear vibrations can be frequently encountered in engineering applications, and take their origin from different sources including contact, friction or large displacements. Other manifestations of nonlinearities are peculiar phenomena such as amplitude jumps, quasi-periodic oscillations and isolated response curves. These phenomena are closely related to the presence of bifurcations in the frequency response, which dictate the system's dynamics. While recent progress has been achieved to develop tools for nonlinear modal analysis of industrial applications, bifurcation analysis was still limited to reduced models and academic case studies. Along with the lack of an efficient algorithm to detect and study bifurcations, bifurcation analysis for design purposes also remained unexplored. The fundamental contribution of this doctoral thesis is the development of a new methodology for the detection, characterization and tracking of bifurcations of large-scale mechanical systems. To this end, an extension of the harmonic balance (HB) method is proposed. Taking advantage of the efficiency of the HB method for the continuation of nonlinear normal modes and frequency responses, this extension allows for robust computation of bifurcation curves in the system's parameter space. A validation of the methodology is performed on the strongly nonlinear model of an Airbus Defence & Space spacecraft, which possesses an impact-type nonlinear device consisting of multiple mechanical stops limiting the motion of an inertia wheel mounted on an elastomeric interface. The second main contribution is the development of a new vibration absorber, the nonlinear tuned vibration absorber (NLTVA), which generalizes Den Hartog's equal-peak method to nonlinear systems. The absorber is demonstrated to exhibit unprecedented performance for the mitigation of nonlinear resonances. In a second step, the HB-based bifurcation methodology is utilized to characterize the performance regions of the NLTVA, and to ensure its robustness with respect to parameter uncertainties. [less ▲]

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See detailẾtude de l’émergence des organisations pastorales et de leur rôle dans les processus de gestion partagée de la vallée de la Tarka dans les départements de Bermo et Dakoro (Centre sud du Niger)
Ibrahim, Habibou ULg

Doctoral thesis (2016)

Cette thèse vise à analyser les organisations pastorales et leurs rôles dans la gestion des conflits fonciers. En Afrique subsaharienne et particulièrement au Niger, le foncier est au centre des enjeux de ... [more ▼]

Cette thèse vise à analyser les organisations pastorales et leurs rôles dans la gestion des conflits fonciers. En Afrique subsaharienne et particulièrement au Niger, le foncier est au centre des enjeux de l’agro-pastoralisme. La sécurisation des droits d’accès aux ressources et des systèmes de tenure foncière sont essentiels pour la gestion et la résolution des conflits fonciers (Herrea et al., 2007). La région de Maradi constitue la zone de contact entre le Nord pastoral et le Sud agricole. Dans cette partie centrale où la pression foncière, aggravée par la croissance démographique, se pose avec acuité, le spectre des conflits fonciers est malheureusement devenu un phénomène chronique, une donnée permanente (GADO., 2000). La pluralité des normes et plusieurs sources de droit contribuent à complexifier le règlement des litiges fonciers entre acteurs dans les départements de Dakoro et Guidan Roumdji (Moutari., 2001). Or la dynamique globale des systèmes d’élevage est déterminée par la complémentarité des espaces agro-pastoraux. Cette complémentarité est remise en cause par ces pressions foncières et suscite des changements organisationnels dans les communautés du centre Sud du Niger (Yamba., 2004 ; 2000). C’est le rôle des associations pastorales à Dakoro et Bermo qui est l’objet de cette recherche. En effet les organisations paysannes en Afrique Subsaharienne et au Niger en particulier jouent un rôle important dans la définition des politiques agricoles et deviennent des conditions indiscutables de la réussite des actions à promouvoir à l’échelle locale (Courade et Deveze., 2006 ; Mercoiret, 2006 ; Mercoiret et al. 2004). La méthodologie de travail relève de l’approche ethnographique. Les outils et instruments d’enquête sont les questionnaires et les entretiens ouverts avec les acteurs locaux sur les dynamiques territoriales, les modes d’action des associations pastorales et les conflits fonciers. Les résultats viennent aussi des travaux et des documents des projets, des ONG et des rapports des services techniques de l’Etat. Pour un souci de fiabilité des données, nous avons tenu à réaliser des séances de restitution des données et de triangulations pour confronter les informations de diverses sources. Au total 104 personnes sont enquêtées dont 30 % auprès des associations. Ces investigations ont concerné aussi les secrétaires des commissions foncières, les préfets, les agents des projets et des ONG et le président du tribunal de Dakoro ainsi que les leaders pastoraux, les transhumants, les agriculteurs et associations pastorales. [less ▲]

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See detailMarket Dynamics in the Financial Industry - Essays on Interdependence and Market Timing
Biell, Elisabeth ULg

Doctoral thesis (2016)

The global financial crisis and the subsequent sovereign crisis are painful reminders of how the standards of financial markets are profoundly challenged in times of crisis. The main lesson is that the ... [more ▼]

The global financial crisis and the subsequent sovereign crisis are painful reminders of how the standards of financial markets are profoundly challenged in times of crisis. The main lesson is that the structural changes and the increased risk of shock transmissions require a more accurate risk assessment that captures the complexity of market dynamics. Based on an empirical approach, this thesis aims at loosening a priori assumptions common in literature in order to develop new methodologies that are more robust and more flexible to the dynamics of changing market conditions. The first aspect of market dynamics addressed in this thesis is the dependence structure of financial markets. The connectedness of the banking and sovereign sectors is dynamically assessed on the basis of daily CDS spreads using complex networks. We turn away from the traditional linear correlation measures and use copula theory to account for extreme events and tail dependence, which is crucial when studying credit and default risk. Through the calculation of minimum spanning trees, our methodology evaluates the transmission pattern of shocks over time and their propagation across geopolitical borders. Going beyond the analysis of simple interdependence, we apply a structural break analysis to measure a contagion index that captures increased co-movements in the network. This thesis tackles a second aspect of market dynamics which relates to major events in the life of a company affecting a company’s market value. By means of operational loss events and cross-listing decisions, we illustrate our refined event study technique that overcomes the drawback of a priori assumptions about the event date. In addition to the reaction magnitude, our approach investigates the point in time when most of the market reaction takes place by highlighting two variables: the start and the length of stock markets' responses. [less ▲]

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See detailContribution to the study of african swine fever in the Democratic Republic of Congo: epidemiological and virological approaches
Mulumba Mfumu Kazadi, Léopold ULg

Doctoral thesis (2015)

Les résultats de cette thèse sont présentés sous la forme d’un ensemble cohérent de quatre études. 1. – Caractérisation moléculaire des souches du virus de la peste porcine africaine (PPA) impliquées dans ... [more ▼]

Les résultats de cette thèse sont présentés sous la forme d’un ensemble cohérent de quatre études. 1. – Caractérisation moléculaire des souches du virus de la peste porcine africaine (PPA) impliquées dans la persistance de l’infection en Afrique centrale (République Démocratique du Congo, RDC). Entre 1997 et 2000, sur 350 prélèvements de sang et organes provenant des porcs apparemment sains, 73 porcs (20,8%) avaient les anticorps dirigés contre la peste porcine africaine (PPA). Au cours de la même enquête, des organes prélevés sur les carcasses des porcs provenant d’une ferme familiale avec des mortalités constatées ont permis la détection de l’ADN du virus de la PPA. La caractérisation du virus a permis d’établir une similarité génétique avec des souches d’Afrique de l’Ouest, notamment du Nigeria et du Ghana. 2. – Estimation de la prévalence de la peste porcine africaine en République Démocratique du Congo et évaluation de la sensibilité et de la spécificité de trois tests ELISA en condition de terrain. Une étude a été menée sur 495 porcs domestiques apparemment en bonne santé de la RDC afin de déterminer le niveau d’exposition au virus de la PPA sur la base de 3 tests ELISA utilisant respectivement comme antigène la protéine VP72 soit sous forme brute (CP72) ou soit sous forme recombinante (rp72) et la protéine p30 recombinante (rp30). En outre, une PCR ciblant la région conservée du gène B646L codant pour la protéine de capside VP72 a été utilisée afin de déterminer l'exposition en fonction du stade de l'infection virus de la PPA. La prévalence apparente (PA) calculée avec les tests ELISA variait de 10% (48/482) avec la RP30 à 22,3% (79/354) avec la rp72. Basé sur des résultats positifs reproduits au moins par deux tests de diagnostic, la PA globale a été estimé à 17% (55/328). Parmi 495 animaux testés par PCR, l’ADN du virus de la PPA a été détecté chez 7 animaux (1,4%), dont 5 porcs séropositifs. En outre, en considérant le test ELISA CP72 comme référence, la sensibilité et la spécificité relatives des tests ELISA rp72 et rp30 ont été estimées sur un sous-ensemble de 328 porcs pour lesquels les résultats à tous les tests étaient disponibles. Le test ELISA rp72 avait une sensibilité relative de 93,5% (IC à 95%: 82,1 à 98,6) et une spécificité relative de 88,0% (IC à 95%: 83,6 à 91,5). Le test ELISA rp30 avait une sensibilité relative de 34,8% (IC à 95%: 21,3 à 50,2) et une spécificité relative de 93,7% (IC à 95%: 89,7 à 95,9). La combinaison globale de la PCR et des trois tests ELISA a révélé que 62% des cas positifs avaient au moins un de leur résultat confirmé par un autre test. Le test ELISA rp72 peut être recommandé dans le dépistage à grande échelle de la maladie dans les zones endémiques de PPA en Afrique comme une alternative au test ELISA de CP72. En outre, le test ELISA de rp30 peut être recommandé pour la confirmation à tout stade de l'infection, y compris dans les plus précoces en parallèle avec la PCR. 3 – La caractérisation génétique des isolats du virus de la PPA impliquées dans les foyers en République Démocratique du Congo, entre 2005 et 2012, révèle une co-circulation de trois Génotypes : I, IX et XIV et 16 variants du virus. L’étude a portée sur 62 pièces anatomiques de rates, ganglions hépato-gastriques, reins, cœurs, poumons, foies et estomacs provenant des 57 carcasses des porcs dont 54 provenant de foyers et 3 provenant des points d’abattage des marchés. L’ensemble représente 25 foyers au total. Ces foyers concernent 5 Provinces de la RDC, dont notamment l’Equateur, le Bas-Congo, le Katanga et Kinshasa. L’étude a révélé la co-circulation de 3 génotypes (I, IX et XIV) et 16 variants du virus. 4 - Immunisation des porcs des races Africaines avec le virus OURT88/3 du Génotype I induit une protection contre l’infection avec deux souches virulentes du Génotype I. La souche atténuée OURT88/3 du virus de la PPA, de genotype I, a déjà démontré son pouvoir protecteur chez les porcs domestiques de races européennes envers les isolats virulents du virus de la PPA. Pour déterminer si les réponses immunitaires protectrices pourraient également être induites chez des porcs de races indigènes de de la région Kinshassa en République démocratique du Congo, nous avons immunisé un groupe de 8 porcs avec la souche atténuée OURT88/3 et infecté les porcs 21 jours plus tard avec la souche virulente OURT88/1 du même génotype. Parmi les 8 porcs, 4 ont été protégés contre l’infection. Trois des 8 porcs sont morts du virus de la PPA et un 4ième est mort de cause inconnue. Les 4 porcs restants ont survécu à une seconde infection avec une souche virulente RDC 085/10 du virus de la PPA, de même génotype. Deux groupes contrôles de porcs non immunisés ont été infectés par la souche OURT88/1 ou la souche RDC 085/10 et ont développé des signes cliniques aigus de la PPA. Ils avaient des niveaux élevés de génome viral dans le sang. [less ▲]

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See detailEstimation of diet digestibility and intake by grazing ruminants through near infrared reflectance spectroscopy analysis of faeces. Application in various contexts of livestock production
Decruyenaere, Virginie ULg

Doctoral thesis (2015)

Grazing is the most economical feeding scheme for ruminants. Grazing management, however, is often difficult for breeders, particularly because of a lack of knowledge about grass availability and quality ... [more ▼]

Grazing is the most economical feeding scheme for ruminants. Grazing management, however, is often difficult for breeders, particularly because of a lack of knowledge about grass availability and quality. There are methods for assessing the quantitative and qualitative characteristics of grass, but they are difficult to apply in the case of grazing ruminants. Near infrared reflectance spectroscopy (NIRS) is based on the absorption of infrared light by organic matters to provide NIRS spectra. These NIRS spectra can be correlated with the chemical or biological composition of samples in order to develop calibrations that can be used as predictive models. The primary objective of this PhD thesis was to study the potential of NIRS applied to faeces (FNIRS) in order to predict the characteristics of the diets of grazing herbivores. The particular focus was on the in vivo organic matter digestibility, voluntary intake and botanical composition of ingested diets. The main results of the study show that FNIRS has great portential for estimating in vivo digestibility and voluntary intake by grazing ruminants and that faeces are a good indicator of ingested diets. Based on both large or small and varied databases, the results suggest that FNIRS spectral libraries could be developed for characterising ruminant feed intake. The accuracy of the FNIRS models in estimating in vivo digestibility and voluntary intake is similar to or better than that of other methods usually used to assess these parameters. FNIRS could also be used to predict ruminants’ diet composition in terms of plant species. These predictions should be used only for ranking, however, because of the current lack of accurate procedures for determining diet selection individually. NIRS applied to faeces can be used to predict the in vivo characteristics of forage with sufficient accuracy. The prediction error of NIRS calibrations depends on the accuracy and precision of the reference data. The prediction of in vivo digestibility and intake is sufficiently repeatable compared with the procedure using the reference method. Intake is more difficult to predict with sufficient precision and is more closely linked to animal variability and to uncertainty of the FNIRS models. The major difficulty in using this method lies in generating the diet-faecal pairs as reliably as possible. FNIRS calibrations for predicting in vivo diet characteristics are derivative calibrations. The sample analysed for reference values (diet samples) differs from the samples submitted to NIRS analyses (faeces). With regard to research on forages, in vivo trials with animals confined in pens or digestibility crates appears to be the best reference method for generating FNIRS calibrations. Future work will involve developing FNIRS calibrations for predicting independent datasets and using them to create decision-support tools for improving diverse grazing management schemes. The major focus should be to compare different feeding strategies rather than to obtain an exact estimate of feed intake values. As a low-cost and rapid prediction technique, FNIRS could contribute significantly to the development of a methodology that would help improve our knowledge of forage and animal variability. [less ▲]

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See detailEcologie et connaissances ethnozoologiques de quelques espèces d'oiseaux gibiers menaces des ecosytèmes du Sud du Bénin
Lougbegnon, Olou Toussaint ULg

Doctoral thesis (2015)

The natural areas of the south of Benin under subequatorial climate are diversified in resident birds’ species as well as migratory one. Some of them are hunted for food and therapeutic purposes by ... [more ▼]

The natural areas of the south of Benin under subequatorial climate are diversified in resident birds’ species as well as migratory one. Some of them are hunted for food and therapeutic purposes by grassroots communities. The most used are Guttera pucherani, Dendrocygna viduata, Egretta alba, Egretta ardesiaca, Porphyrio alleni et Porphyrio porphyrio. In order to reduce pressure on biodiversity in this part of Benin and to implement the sustainable conservation of birds’ species, this study on ecology and ethno-zoological knowledge of hunted bird species was carried out in the forest areas and the Ramsar sites 1017 and 1018. Field prospections were conducted from 2009 to 2012. The birds’ inventory method used was based on listening point techniques of 15 minutes. Data analysis were analyzed through the computation of bird species abundances, the establishment of maps distribution of the species, the habitat description and the modeling of the climatic niche of these species under climatic models CCCMA (Canadian Centre for Climate Modeling and Analysis) and CSIRO (Commonwealth Scientific and Industrial Research Organization) using MAXENT3.3.2. The ethno-zoological knowledge of the birds species were assessed through individual and groups survey and allowed to calculate the use values of the different part of the birds’ species according to the socio-cultural groups, sex and age. Moreover a logistic binary regression was carried out to determine the socio-economic factors which affect bird species exploitation by the grassroots communities. Results of modeling showed that among the variables selected for the prediction of the climatic models, distance from river, altitude appeared as the environmental variable which more contributed to the prediction of the models (with an average of 74.32 % and 12.94%). Projection under CCCMA and CSIRO in 2050, showed a progression of the favorable areas to Dendrocygna viduata, Porphyrio alleni, Porphyrio alleni, Egretta ardesiaca while it showed a regression of the favorable areas to Egretta alba. The estimated uses values showed that the ethno-zoological knowledge on the bird species differed according to the ethnic groups. Birds are used for food, medicinal and magico-mystics purposes. The magico-mystics and food were the most frequent used categories. Homogeneity of knowledge was found among the informants regarding the ethnic group as well as for the sex with respectively 0.66 and 0.7 for the use diversity value (ID) and use equitability value (IE). No significant difference was found between the informant for the use diversity value (ID) and use equitability value (IE). This study helps to build a database on 6 birds’ species and can be used for bird game ranching and game farming in Benin. [less ▲]

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See detailTranscriptomic analysis of pancreatic cells in zebrafish
Tarifeño Saldivia, Estefanía ULg

Doctoral thesis (2015)

Pancreas is a mixed gland composed of endocrine and exocrine tissues and plays a crucial role in the metabolism of all vertebrates. The endocrine cells are mainly grouped into the islets of Langerhans and ... [more ▼]

Pancreas is a mixed gland composed of endocrine and exocrine tissues and plays a crucial role in the metabolism of all vertebrates. The endocrine cells are mainly grouped into the islets of Langerhans and secrete distinct hormones, such as glucagon (α-cell), insulin (β-cell), somatostatin (δ-cell) and ghrelin (ε-cell). Diabetes occurs when insulin production by the β-cells is unable to counteract increase of glycemia. The goal of the first part of my thesis was to determine the transcriptomic signatures of each pancreatic cell type in zebrafish in order to identify novel cell type-specific regulatory genes that might be crucial for their differentiation and/or physiology. Pancreatic acinar cells, ductal cells as well as the endocrine α-, β- and δ-cells were isolated from different transgenic adult zebrafish using FACS and RNA-seq was performed from these highly purified cell types. Comparison between the RNA-seq datasets allowed us to highlight all genes (protein coding and non-coding genes) with enriched expression in each cell type and to identify new markers of the mature pancreatic cells in zebrafish. In order to establish the expression blueprint of pancreatic endocrine and exocrine cells conserved from fish to mammals, we compared the pancreatic transcriptomes from zebrafish, mouse and human. Using pancreatic RNA-seq data available in databases, we determined the set of genes displaying enriched expression in endocrine and exocrine cells of human and mouse. Comparison of these data with the zebrafish pancreatic endocrine and exocrine data revealed the genes with conserved expression among vertebrates. Most of the transcription factors previously known to be important for pancreatic cell differentiation are included in this set of conserved genes. This interspecies comparative analysis highlighted genes with evolutionary conserved expression whose pancreatic function is still unknown, but also revealed striking differences in gene expression patterns between species. The goal of the second part of my thesis was to understand the global transcriptional change produced by the loss-of-function of pax6b in pancreatic endocrine cells during pancreas development in zebrafish. We performed RNA-seq from purified pancreatic endocrine cells from wild-type and mutant (pax6b sa0086 null allele) zebrafish embryos at 27 hpf. By comparing the transcriptome of wild-type and mutant endocrine cells, we identified thousands of genes differentially expressed. Notably, we observed that the expression level of the pancreatic hormones was affected as it was reported in murine models. These analyses have revealed the transcriptional network regulated by pax6b in endocrine cells during differentiation. These analyses highlighted many unknown pax6b targets and novel regulators possibly involved in pancreatic function. Future functional analyses will be needed to further investigate the function of the novel regulators identified by this study. [less ▲]

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See detailScène d'énonciation et posture d'auteur: la mise en scène de soi dans la critique littéraire de Baudelaire
Mogollon Zapata, Juan Manuel ULg

Doctoral thesis (2015)

Il y aurait un Baudelaire réaliste, un décadent, un classique, un catholique, un révolutionnaire, un réactionnaire et même un postmoderne. Les images attribuées à l’auteur se superposent selon l’époque ... [more ▼]

Il y aurait un Baudelaire réaliste, un décadent, un classique, un catholique, un révolutionnaire, un réactionnaire et même un postmoderne. Les images attribuées à l’auteur se superposent selon l’époque, le lieu et les courants esthétiques et politiques dans lesquels il a été lu. Mais quelle image Baudelaire construit-il de lui-même dans ses textes critiques ? Comment s’y présente-t-il à son public ? Pour mieux cerner le visage littéraire de cette figure changeante et paradoxale, l’étude proposée ici cherche à démontrer qu’il existe bel et bien dans la critique littéraire de Baudelaire un travail de mise en scène de soi qui ne peut se comprendre qu’à partir des diverses scènes d’énonciation que le poète-critique a capitalisées tout au long de sa carrière. Cela soulève la question de la relation entre, d’un côté, la présentation de soi et la scène de parole dans laquelle elle s’inscrit et qu’elle aide à construire, et de l’autre, entre cette mise en scène discursive de soi et les stratégies de positionnement de l’auteur à l’intérieur du champ littéraire. Dans quelle mesure ce travail de présentation de soi est-il redevable de la "situation de discours" dans laquelle il s’énonce ? Et, corollairement, dans quelle mesure relève-t-il d’une stratégie de positionnement littéraire ? Dès que l’on constate que le choix d’une posture, ou de diverses postures au fil du temps, est à la fois lié à une scène d’énonciation, à une étape socioprofessionnelle et à un répertoire de rôles et de modèles prêts à être investis, on entre dans la logique de construction d’une œuvre, mais aussi d’une identité littéraire. [less ▲]

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See detailLe vécu des femmes magistrates en Belgique francophone. Analyse d'une profession sous l'angle des rapports sociaux de sexe. Représentativité, profils et pouvoir
Cornet, Adeline ULg

Doctoral thesis (2015)

Sachant qu’historiquement l’exercice de la Justice a été réservé aux hommes, et que les femmes n'ont accès, en Belgique, que depuis un peu moins de 70 ans à la magistrature ; la question centrale de cette ... [more ▼]

Sachant qu’historiquement l’exercice de la Justice a été réservé aux hommes, et que les femmes n'ont accès, en Belgique, que depuis un peu moins de 70 ans à la magistrature ; la question centrale de cette recherche doctorale s’attache à étudier l’impact de l’arrivée des femmes dans la magistrature et de leur exercice de cette fonction régalienne et de pouvoir, ainsi que de leur vécu personnel et professionnel. Choix a été fait d’aborder cette question centrale suivant une méthodologie qualitative et l’utilisation de récits de vie ; et les résultats obtenus y répondent à travers trois grands axes analytiques pouvant être résumés en trois questions : 1/ Combien sont ces magistrates et « où sont-elles » ? Quelle a été l'évolution numérique des femmes dans la magistrature au cours du temps ? Quels postes et quelles fonctions occupent-elles ? 2/ Qui sont les magistrates et comment se définissent-elles ? Quels sont leurs profils et leurs trajectoires professionnelles ? Quel sens, quelles significations donnent les magistrates à leur profession et à la place qu'elle tient dans leur vie ? Quel est leur vécu ? 3/ Quelle vision ont les magistrates du pouvoir ? Et comment se positionnent-elles face à cet attribut central de leur profession ? Ces analyses, réalisées à travers la comparaison des parcours et vécus des quarante-neuf magistrates interrogées, se veulent être une première étude de genre de cette profession visant à connaître qui sont ces magistrates, la place qu'elles occupent dans la profession, la manière dont elles l'envisagent et lui donnent sens. [less ▲]

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See detailLe financement de l’agriculture au Bénin : stratégies de gestion et d’adaptation des exploitations agricoles
Sossou, Comlan Hervé ULg

Doctoral thesis (2015)

Benin is highly dominated by agriculture: about 80 % of the population are rural and involved in farming activities. The challenge now is to create suitable conditions for the improvement and ... [more ▼]

Benin is highly dominated by agriculture: about 80 % of the population are rural and involved in farming activities. The challenge now is to create suitable conditions for the improvement and competitiveness of farming systems and the creation of small and medium enterprises along the different chains of agricultural value. One such challenge involves facilitating the access of farmers and other stakeholders, to input markets, products and especially financial services. This highlights the need to establish an optimal framework for financing agricultural activities based on lessons learned from current experiences and using the best recent institutional innovations in the field. This thesis focuses on the issue of funding for agriculture and strategies developed by producers and other stakeholders including the public sector. To understand agricultural activities financing problems in rural areas, a research was conducted from 2010 to 2014. The research targets are farms and their access to financial services. A survey of 475 farms was conducted in 2011. In 2014, a deepening phase was performed on 40 farms. Research results revealed that financial needs of farms are not totally satisfied. The loans granted are small amounts, mostly. Productive investments that constitute investments in medium and long term, which can lead to significant improvements in agricultural production, are almost unsatisfied. Moreover, analysis showed that income determines access to credit. This factor reflects to a certain level the ability of farmers to provide the financial guarantees required by microfinance institutions. Also, producer's ability to invest and to provide the required guarantees, his loyalty and compliance with the rules of microfinance institutions (MFIs) facilitate access to high loan amounts. Analysis also showed that credit rationing affects a large number of producers. The consequence of this rationing is the reduction in agricultural inputs use, in hired labour, in acreage, etc. And therefore, decrease in yields and producers incomes. In summary, current conditions offered by microfinance institutions is not conducive to agricultural development and livelihoods improvement of rural populations. It is therefore necessary to rethink agricultural activities funding and develop a sustainable financing mechanism for both producers and funding agencies. To this end, the initiative for the establishment of a National Fund for Agricultural Development (NFAD) should be accelerated to allow farmers easier access to credit and adequate. [less ▲]

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See detailEtude des principes supranationaux de prévention des conflits armés - Exemple du système éducatif primaire de Prishtina (Kosovo)
Pierre, Alexia ULg

Doctoral thesis (2015)

The Unmik, United Nations Mission in Kosovo, was launched in the aftermath of mass violations of War Law and of International Humanitarian Law, perpetrated by the Republika Srpska against the Albanian ... [more ▼]

The Unmik, United Nations Mission in Kosovo, was launched in the aftermath of mass violations of War Law and of International Humanitarian Law, perpetrated by the Republika Srpska against the Albanian civilian of Kosovo. The Unmik was mandated to prevent the interethnic violence and to neutralise the roots of conflict, and to let emerge a new society where intercommunity antagonisms do not exist anymore. The mass education appears to be a tool that leads to a sustainable development of society. Therefore, the International Community links education and conflict prevention due to the role of education in social integration and development, and through specific contents. The supranational principles of education to conflict prevention are framed by an international framework, mostly developed in the nineties. Finally, education was at stake and was instrumentalised by the nationalist propagandas during the conflict between Serbs and Albanian in Kosovo. The main object of this research is to explore the way these principles of education to conflict prevention are operationalized in the primary public education system in Kosovo, through the study case of the main city Prishtina. The premise is that the operationalization can carry some boundaries to the complete expression of these supranational principles. The first step was dedicated to the research of the supranational principles in a normative and legislative corpus of local texts. The second step was a study of the expression of the principles of prevention in the primary public schools of Prishtina and with some members of the education system of Kosovo. This work highlights the sustainability of the operationalized principles on the formal and structural stages, due to the integration in the local normative and legislative frame. However, the operationalization can lead to an incomplete or a limited expression of the principles of an education involved in the conflict prevention. The top down approach of the Unmik and its lack of practical application of the principles are important elements in the limited expression of these principles. The boundaries are linked to the failure in questioning the education model applied in Kosovo as well, and to the assumptions it carries. Finally, the inadequate support to the educational staff and the inadequacy of this education model to the specificities of Kosovo are equally major factors of the limited operationalization of the supranational principles of conflict prevention in the primary schools of Prishtina. [less ▲]

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See detailEtude des apports de l'épidémiologie participative à l'évaluation des systèmes de surveillance en santé animale
Calba, Clémentine ULg

Doctoral thesis (2015)

Les systèmes de surveillance en santé animale sont mis en place dans le but de répondre à des enjeux de santé publique et de santé animale, ils permettent également de limiter les pertes économiques et de ... [more ▼]

Les systèmes de surveillance en santé animale sont mis en place dans le but de répondre à des enjeux de santé publique et de santé animale, ils permettent également de limiter les pertes économiques et de préserver la biodiversité. Du fait de l’importance capitale de ces systèmes tant au niveau national qu’international, il est fondamental de mettre en place des évaluations régulières et pertinentes afin de s’assurer de leurs performances, mais également dans le but de déterminer si les ressources fournies sont utilisées de manière optimale. Différents guides ont été développés afin d’accompagner les évaluateurs dans cette démarche, en santé animale tout comme en santé humaine, décrivant avec plus ou moins de détails comment identifier et mesurer les différents attributs d’évaluation (e.g. sensibilité, représentativité). Les processus d’évaluation proposés et actuellement appliqués présentent cependant certaines limites, telles qu’un manque de flexibilité dans la prise en compte du contexte, et la faible prise en considération des aspects socio-économiques de la surveillance. Pour pallier ces manques, il a été proposé d’utiliser des approches participatives afin de déterminer les perceptions, attentes et besoins des différents acteurs impliqués dans la surveillance. L’objectif de ce travail de recherche était ainsi de déterminer l’apport de l’épidémiologie participative à l’évaluation des systèmes de surveillance en santé animale. Afin de déterminer les attributs d’évaluation pour lesquels la mise en place d’approches participatives peut apporter une valeur ajoutée, un travail de revue et d’analyse critique des méthodes actuellement utilisées pour leur mesure a été réalisé. Ce travail a permis d’identifier trois niveaux d’utilisation possibles de l’épidémiologie participative : (i) la mesure d’un attribut d’évaluation dans son ensemble, (ii) l’appui à la collecte de données nécessaires à l’estimation de l’attribut d’évaluation, et (iii) la collecte d’informations complémentaires permettant d’interpréter les résultats de l’évaluation. Pour ce travail, deux attributs ont été sélectionnés : l’acceptabilité, qui réfère à la volonté des acteurs de participer à la surveillance et pour lequel une méthodologie d’évaluation participative complète a été développée ; les bénéfices non-monétaires, qui réfèrent aux conséquences positives directes et indirectes produites par le système pour les utilisateurs et pour lequel une méthodologie de collecte de données nécessaires à son estimation a été développée. Ces méthodologies ont été appliquées dans deux études de cas : le système de surveillance de la peste porcine africaine en Corse (étude pilote), et le système de surveillance de la tuberculose bovine en Belgique. Ces travaux ont permis de mettre en avant la faisabilité d’utiliser des approches participatives dans des contextes développés, avec des acteurs variés tels que les éleveurs, les services vétérinaires ou encore les agents de laboratoires. Ils ont également permis d’aboutir à une méthodologie participative globale pour mesurer l’acceptabilité : « AccePT » (Acceptability Participatory Toolkit). Concernant les bénéfices non-monétaires, l’utilisation d’une méthode d’estimation contingente associée à un empilement proportionnel a permis d’identifier les informations sanitaires d’intérêt pour les éleveurs, et d’estimer la valeur économique de ces informations pour ces acteurs. Cependant, la méthode développée nécessite encore des ajustements. Faisant suite à ces différents travaux, les bénéfices liés à l’application de l’épidémiologie participative pour l’évaluation des systèmes de surveillance en santé animale ont pu être mis en avant. En effet, celle-ci permet de formuler des recommandations pour l’amélioration de la surveillance basées sur le contexte et prenant en considération les perceptions, attentes et besoins des différents acteurs impliqués. Par une implication directe des acteurs dans le processus d’évaluation au travers des entretiens ouverts, elle permet d’aboutir à une meilleure acceptabilité de celui-ci. Elle offre également l’opportunité de collecter des données complémentaires sur le contexte général dans lequel la surveillance est mise en place, sur le système ainsi que sur des attributs d’évaluation différents des attributs ciblés à l’origine, tels que l’offre de formation et la communication. Cette implication directe des acteurs aide également au renforcement du sentiment d’appartenance des parties prenantes au système de surveillance ciblé, ainsi qu’à une sensibilisation des acteurs vis-à-vis du fonctionnement de ce système et des maladies ciblées. Ces bénéfices sont malgré tout à contrebalancer avec les limites et biais de ces approches, tels que le temps nécessaire à la mise en place et à l’analyse des entretiens et la sélection des participants. L’application de méthodes et d’outils participatifs dans le cadre de la surveillance permet ainsi d’optimiser l’évaluation de ces systèmes. Cependant, leur intérêt dépendra fortement du contexte dans lequel les outils seront appliqués, ainsi que des contraintes liées au processus d’évaluation. [less ▲]

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See detailLaser cooling of iron atoms
Huet, Nicolas ULg

Doctoral thesis (2015)

The work presented in this thesis is dedicated to the development and implementation of a cold atom experiment which handles an atomic species that has not been cooled down so far: iron. The experiment ... [more ▼]

The work presented in this thesis is dedicated to the development and implementation of a cold atom experiment which handles an atomic species that has not been cooled down so far: iron. The experiment requires the use of two UV laser radiations (at 372 and 358 nm) that are frequency stabilized by means of saturation spectroscopy, an iron atomic beam, and a vacuum system, which we contributed to implement and characterize. In addition to this development, several spectroscopic studies were carried out in this thesis. By means of saturation spectroscopy, the hyperfine structure of the molecular-iodine R(90)3-10 transition at 716 nm was first studied following its involvement in the frequency stabilization of the 358-nm radiation. A spectroscopic study of the 358-nm Fe I cooling transition, which was totally unknown prior to this thesis, was also conducted using laser-induced fluorescence spectroscopy. With the same technique, a high accuracy measurement of the iron 358-nm transition frequency with respect to the molecular-iodine R(90)3-10 transition was performed. For this measurement, we implemented a particular configuration which allowed for the minimising of an important systematic error. The first laser cooling of iron is also reported. For this purpose, the Zeeman slowing technique was implemented following a particular two-laser scheme. To our knowledge, this Zeeman slower is the first of this kind. Furthermore, the complete characterization of the cold iron atomic beam produced at the output of the Zeeman slower was done, which allowed for an optimized loading of the magneto-optical trap. Finally, the creation of a cold cloud of iron atoms demonstrated the Zeeman slower ability to properly load an iron magneto-optical trap. [less ▲]

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See detailIndication géographique au Vietnam : Cas du thé vert Tan Cuong, Thai Nguyen
Dang, Thi Minh Luyen ULg

Doctoral thesis (2015)

The Tan Cuong green tea is highly-appreciated since a long time for its quality, according to the Vietnamese consumers. This tea has been recently certified "Geographical Indications (GI)" by the National ... [more ▼]

The Tan Cuong green tea is highly-appreciated since a long time for its quality, according to the Vietnamese consumers. This tea has been recently certified "Geographical Indications (GI)" by the National Office of Intellectual Property of Vietnam. Within the framework of PIC project "Development of the medium and small entrepreneurship in the Vietnam agricultural sector" - financed by the University Commission for Development (CUD), Belgium, Hanoi University of Science and Technology had led a multidisciplinary research on this certified tea product fora better understanding of pros and cons of GI and to identify the constraints of the producers. Pursuing these purposes, three researches related to Tan Cuong green tea were conducted on the commodity, the consumers and the characteristics of products. The commodity research aims to reveal the situation and the problems of tea production in Tan Cuong region. It es based on the survey of 90 households’ producers, combined with in-depth interviews with numerous traders and related suppliers in this area and Hanoi. The second research was a survey which focused on 150 consumers in Hanoi capital, the main market of Tan Cuong green tea to comprehend their perceptions, their opinions and their recommendations for the product. The last study has conducted to contribute to a better knowledge of the product quality. The sensory analysis and bibliographical research on the chemical components of Tan Cuong green tea have been applied to reach this purpose. The result shows that Tan Cuong green tea is a high quality and a high economic profit product. The consumers appreciate the quality of Tan Cuong green tea and expressed an expectation for a healthy and quality tea product. In short, based on the results of various researches, three main recommendations can be drawn: the first one highlights the importance of implementing the GI control system for Tan Cuong green tea, the second one underlines the interest for the Tan Cuong green tea production with an organic label and the third one aims at strengthening the cooperation of all the accors of this sector. [less ▲]

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See detailModelling of cooling and heat treatment of bimetallic rolling mill rolls
Neira Torres, Ingrid ULg

Doctoral thesis (2015)

This work is focused on the modelling of post casting cooling and heat treatment stages, using a coupled thermo-mechanical metallurgical model in order to understand the behavior of bimetallic rolling ... [more ▼]

This work is focused on the modelling of post casting cooling and heat treatment stages, using a coupled thermo-mechanical metallurgical model in order to understand the behavior of bimetallic rolling mill rolls. The case of interest is a bimetallic rolling mill roll which materials and geometry present a risk of failure in industrial manufacturing. The analysis of residual stress fields together with a rough damage approach allows the understanding of the failure event and predicting trends when industrial conditions are modified. Performed finite element modelling requires a complete set of materials parameters. Experimental and numerical methods are applied in order to obtain thermophysical, mechanical, metallurgical and coupled parameters. Sensitivity analysis is performed in order to evaluate the effect of numerical predictions to different input data, modeling eventual modifications of materials or geometries. Finally, conclusions and perspectives obtained from this research allow establishing some weakness of the implemented model, enhancing the importance of considering more advanced damage models. In addition, it is settled that the material characterization must be improved by considering materials pollution and complexity. However the work provides a convincing explanation of the observed phenomena of ruptures. [less ▲]

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See detailSynthesis and characterization of novel donor-acceptor isoindigo-based conjugated copolymers and small molecules and their integration in organic photovoltaics
Tomassetti, Mirco ULg

Doctoral thesis (2015)

The conversion of solar energy into electricity is an environmentally friendly, safe and low- cost way of renewable energy production. Among the different photovoltaic technologies, organic photovoltaics ... [more ▼]

The conversion of solar energy into electricity is an environmentally friendly, safe and low- cost way of renewable energy production. Among the different photovoltaic technologies, organic photovoltaics (OPV) have particular assets in terms of aesthetics, flexibility and low-cost large area coverage. Nevertheless, the moderate OPV efficiencies (˞11%) and lack of durability (< 10 years) strongly limit their large-scale exploitation in particular consumer goods. The main goal of this thesis is to deal with these two drawbacks by designing novel conjugated polymers and small molecules with broad absorption in the visible range (i.e. low band gap), and by setting up strategies to improve the (thermal) stability of the photovoltaic cells. To this extent, novel push-pull type organic semiconducting materials have been synthesized, with different architectures and composed of electron-poor isoindigo building blocks alternating with electron-rich moieties, presenting a favorable spectral overlap with the solar emission. The optical properties of the novel materials were generally investigated by UV-visible absorption spectroscopy, while cyclic voltammetry was implemented to estimate the frontier orbital (HOMO/LUMO) energy levels. Relationships between the chemical nature and architecture of the push-pull systems and their absorption spectra and HOMO-LUMO energy levels have been pursued. Finally, the photovoltaic performances of the new materials have been evaluated in conventional bulk heterojunction organic solar cells using methanofullerene acceptor materials. Correlations between the molecular and photovoltaic parameters have been established. Ultimately, cross-linkable diblock copolymers based on poly(3-hexylthiophene) (P3HT) have been synthesized to improve the long-term stability of P3HT/PC61BM photovoltaic cells. Bulk heterojunction polymer solar cells have been prepared and their stability has been evaluated by accelerated ageing experiments and compared with standard P3HT-based devices. [less ▲]

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See detailLes carrières des cadres : le genre à l'épreuve des catégories d'âge
Grodent, Françoise ULg

Doctoral thesis (2015)

Le but de notre thèse est de savoir, si en termes de carrières et de conciliation avec la vie privée et/ou familiale des cadres, il existe un effet d'âge qui se superpose à celui du sexe. En effet, il ... [more ▼]

Le but de notre thèse est de savoir, si en termes de carrières et de conciliation avec la vie privée et/ou familiale des cadres, il existe un effet d'âge qui se superpose à celui du sexe. En effet, il existe peu de travaux sur les carrières des cadres qui ont intégré la thématique de l'équilibre entre les sphères privée et professionnelle ainsi qu'une approche intersectionnelle qui conjugue les rapports sociaux de sexe et d’âge. Pour analyser les carrières subjectives des cadres et la conciliation avec leur vie privée et/ou familiale, nous avons opté pour les lunettes d'analyse du genre permettant de dépasser la comparaison hommes-femmes et de tenir compte de l'évolution de la socialisation ainsi que des opportunités historiques des hommes et des femmes dans le travail et dans la famille. En effet, nous ne pouvons pas étudier la carrière des hommes et des femmes sans tenir compte de leur âge et du fait qu'ils ne disposent pas, notamment, des mêmes ressources et des mêmes attributions. Etant donné notre objet d'étude, nous avons opté pour une approche qualitative, exploratoire et inductive. Nos données empiriques ont été récoltées via des entretiens semi-directifs menés auprès de 104 cadres dans une optique de "storytelling". Elles ont été traitées par l'intermédiaire d'une analyse de contenu qualitative thématique et d'une analyse structurale du discours des cadres. Les préoccupations liées à l'évolution historique de la place des hommes et des femmes au travail et dans la famille transforment les relations entre les sexes tant aux niveaux professionnel que familial. L'intersectionnalité des rapports sociaux de sexe et d'âge génère donc des portraits de carrière et de conciliation avec la vie privée et/ou familiale différents pour chacun de nos six sous-groupes de cadres. Les orientations professionnelles et de conciliation ne sont pas uniquement le fruit de décisions ou de contraintes individuelles. En effet, d'autres niveaux d'influence (relationnel, groupal, organisationnel, institutionnel, etc.) interviennent que ce soit au point de vue du travail ou de la famille. [less ▲]

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See detailHeavy-chain antibody fragments as model proteins to investigate the molecular mechanism of formation of amyloid fibrils
Chavignon, Chloé ULg

Doctoral thesis (2015)

Amyloidoses are rather common and widespread debilitating and/or life-threatening diseases. They display structurally identical amyloid fibrils, and consequently appears to share a common, but still ... [more ▼]

Amyloidoses are rather common and widespread debilitating and/or life-threatening diseases. They display structurally identical amyloid fibrils, and consequently appears to share a common, but still poorly understood, mechanism of fibrillogenesis. Variable domains of camelid heavy-chain antibodies, referred to as VHHs or nanobodies, were chosen to investigate the factors that favour amyloid fibrillogenesis and to get a better understanding of the mechanism of Ig fibrillogenesis. Our study focused on the contribution of protein regions, i.e. the framework (FR) and the complementary determining regions (CDRs) of VHHs, to the formation of amyloid fibrils. Three VHHs were selected: cAb HuL6, cAb BcII10 and cAb BcII10 H H H, a chimera bearing the FR of cAb BcII10 and the CDRs of cAb HuL6. We first established experimental conditions suitable for fibrillogenesis: even the especially stable and soluble VHHs can form amyloid fibrils in denaturing conditions. This comforts the proposal that amyloid conformation is a generic structural form that all proteins can adopt in the appropriate conditions. Amyloid fibrils were characterised by transmission electron microscopy (TEM), circular dichroism (CD), thioflavin T (ThT) fluorescence and X-ray fibre diffraction. The kinetics of fibril formation were monitored by turbidity measurements. We then determined conditions suitable for characterising self-seeding and cross-seeding kinetics, and ascertained that the three VHHs convert into amyloid fibrils according to a nucleation-dependent process. Fibril elongation rates in self-seeding and cross-seeding experiments suggest that amyloid fibril elongation occurs through sequential addition of protein monomers to preformed fibrils. The kinetics of aggregation and self-seeding of cAb-HuL6 and cAb-BcII10 differ significantly, and a remarkable specificity for cross-seeding was observed, with cAb-BcII10 being unable to cross-seed the formation of fibrils by the two other VHHs, while cAb-HuL6 and cAb BcII10 H-H-H mutually cross-seed each other’s fibril formation. With the help of three prediction algorithms (AGGRESCAN, Zyggregator and 3D-profile), we showed that various peptides of the VHHs had the ability to form fibrils by themselves. Our results strongly suggest that the sequences of the regions forming the core of the fibrils essentially correspond to the CDRs. Concurrently, we set up experimental conditions for interrupting the fibril formation process and we characterised the multimer and fibril species formed in the early stages of fibrillogenesis by analytical ultracentrifugation (AUC) and small angle neutron scattering (SANS) ex situ. [less ▲]

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See detailDesign of a single-species biofilm reactor based on metal structured packing for the production of high added value biomolecules
Zune, Quentin ULg

Doctoral thesis (2015)

Thesis summary In the last decade, numerous single-species biofilm reactors of various configurations have been implemented at lab and pilot scale for the production of chemicals and biological products ... [more ▼]

Thesis summary In the last decade, numerous single-species biofilm reactors of various configurations have been implemented at lab and pilot scale for the production of chemicals and biological products. Compared to their counterparts in submerged cultures, these processes benefit from the specific physiology of biofilms, i.e. high robustness of the microbial system, long-term activity, continuous implementation and low ratio size / productivity. However, the risks of biofouling and the lack of analytical tools for the control and the monitoring of biofilms are obstacles for scale-up strategies. Up to now, single-species biofilm reactors have been mainly confined to the production of metabolites ranging from low (bulk chemicals) to medium (fine chemicals) added values. In this way, there is a need to design efficient single-species biofilm reactors exhibiting good scalability potentials and intended for the production of high added value compounds. In this work, an experimental single-species biofilm reactor has been designed for the production of target molecules derived from metabolic pathways involved in biofilm physiology. On the basis of these criteria, three biological models having good abilities of biofilm formation and secretion performances were selected : - the gram positive bacterium Bacillus subtilis for the production of surfactin, a surface active metabolite involved in biofilm formation. - the filamentous fungus Trichoderma reesei for the production of hydrophobin (HFBII), a surface active protein (7kDa) involved in adhesion process of spores and mycelium on solid surface. - the filamentous fungus Aspergillus oryaze (engineered strain) for the production of a recombinant protein (Gla::GFP) under the control of the glaB promoter specifically activated in solid-state fermentation. The proposed experimental biofilm reactor has the configuration of a trickle-bed bioreactor. The agitation axis of a stirred tank reactor has been removed and replaced by a stainless steel structured packing filling the top of the vessel. The liquid medium, located in the bottom of the vessel is continuously recirculated on the packing element thanks to a peristaltic pump. An ascending air flow is performed above the liquid phase just under the packing element. This thesis reports the screening of the three biological models in the experimental biofilm reactor. The results include the characterization of process performances in terms of biofilm formation and secretion of the target molecule under different operating conditions. An original methodology based on high energy X-ray tomography has been developed to non-invasively visualize and quantify the biofilm colonization inside the packing element. This technique has highlighted that biofilm colonization and liquid phase distribution across the packing are strongly interrelated phenomena. The biofilm of B. subtilis occurring by cell aggregation preferentially developed on solid areas wetted by the liquid. Accordingly, optimal operating conditions improving liquid phase distribution have been defined for biofilm colonization. The fungal biofilm of A. oryzae and T. reesei occuring by cell filamentation equally colonize submerged and aerial surfaces of the packing element. Consequently, another configuration of biofilm reactor comprising a packing element totally immersed in the liquid medium has been investigated. The production yields of surfactin and hydrophobin in the experimental biofilm reactor are respectively 1.25 and 2.64 times greater than those of a submerged culture in a stirred tank reactor. This suggests that surface-active molecules involved in biofilm formation have a real interest for the design of single-species biofilm reactors. Although the Gla::GFP fusion protein is greater produced in the stirred tank culture, its integrity was preserved in the biofilm reactor despite the presence of proteases. This suggests that the quality and the stability of heterologous proteins produced in a fungal biofilm reactor are improved compared with a submerged culture. Finally, the implementation of the biofilm reactor has led to technological progresses including low energy consumption, no foam formation, continuous processing and simplification of downstream process operations. Further experiments should deepen the understanding of structured phenotypic heterogeneity impact on secretion performances in the biofilm reactor. These experiments should consider development of operating conditions allowing for the growth of a thin biofilm homogeneously distributed on the whole surface provided by the packing element in order to optimize nutrients and metabolites mass transfers. The scale-up and the continuous implementation of the process should be also investigated. [less ▲]

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See detailRoot-emitted volatile organic compounds in belowground plant-plant interactions
Delory, Benjamin ULg

Doctoral thesis (2015)

Plants are able to synthesise and release volatile organic compounds (VOCs) aboveground (leaves, stems, flowers and fruits) and belowground (roots). Once emitted, these molecules are key mediators in ... [more ▼]

Plants are able to synthesise and release volatile organic compounds (VOCs) aboveground (leaves, stems, flowers and fruits) and belowground (roots). Once emitted, these molecules are key mediators in biotic interactions as they can be perceived by plant neighbours (first trophic level) and are able to attract/repel organisms of the second (insect herbivores, plant parasitic nematodes) or the third trophic level (entomopathogenic nematodes, parasitoids, etc.). Although many laboratory and field experiments have focused on VOC-mediated plant-plant interactions aboveground, less is known regarding the roles played by root-emitted VOCs in between- and within-plant signalling. In this context, the main goals of this PhD thesis were to (1) identify and quantify the VOCs emitted by barley and chamomile roots and (2) study the influence of chamomile root volatiles on the growth (biomass production and allocation) and the root system architecture (RSA) of barley (interspecific model). Root-emitted VOCs were analysed without extracting the roots from the soil (in situ) using a three-step gas chromatography-mass spectrometry methodology. Plant-plant interaction bioassays were performed using an original experimental device allowing the controlled exposition of growing barley roots to the volatile compounds emitted by chamomile roots for 15 days. In order to speed up the RSA analysis of recipient barley plants, we developed an R package (archiDART) allowing (1) the batch processing of the raw data exported by Data Analysis of Root Tracings (DART) and root image analysis software tools supporting the Root System Markup Language (RSML) format, and (2) the automated computation of RSA traits. Our results showed that crushed barley roots produced mainly hexanal, (E)-hex-2-enal, (E)-non-2-enal and (E,Z)-nona-2,6-dienal. Three-day-old seminal roots were characterised by higher total and individual VOC concentrations compared with older phenological stages. Our experiments also showed that enzymatic activities were required for volatile production. For each developmental stage, the lipoxygenase (LOX) specificity was greater for linoleic acid than for α-linolenic acid. The greatest LOX activities using linoleic and α-linolenic acids as substrates were measured in 7- and 3-day-old roots, respectively. Although undamaged barley roots did not release detectable amounts of VOCs, the analysis of VOCs emitted by mechanically injured roots showed that (E)-non-2-enal (13.8 ± 4.9 ng/g dry wt/h) and (E,Z)-nona-2,6-dienal (4.7 ± 1.8 ng/g dry wt/h) were the only VOCs detected in the plant rhizosphere. Contrasting with these results, the undamaged roots of 61- to 78-day-old chamomile plantlets released mainly one trinorsesquiterpene (albene) and four tricyclic sesquiterpene hydrocarbons (silphinene, modheph-2-ene, α-isocomene and β-isocomene) associated with the Asteraceae family. For each sesquiterpene hydrocarbon, the emission rate was positively correlated with plant age. Based on these results, we performed plant-plant interaction bioassays to investigate the roles played by chamomile root volatiles on the growth and RSA of barley. After 15 days of exposure, plants exposed to the volatiles emitted by the soil and chamomile roots or by the soil alone (control) were morphologically similar. Although not statistically significant (P < 0.09), the leaf area and the total seminal root length were the only parameters that tended to be greater in plants that received the volatile compounds emitted by chamomile roots compared with control plantlets. All these results are discussed in the context of belowground chemical ecology. In addition, some improvements of the experimental devices developed in this research project are also suggested at the end of this PhD thesis. [less ▲]

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See detailEulerian Formulation of Spatially Constrained Elastic Rods
Huynen, Alexandre ULg

Doctoral thesis (2015)

Slender elastic rods are ubiquitous in nature and technology. For a vast majority of applications, the rod deflection is restricted by an external constraint and a significant part of the elastic body is ... [more ▼]

Slender elastic rods are ubiquitous in nature and technology. For a vast majority of applications, the rod deflection is restricted by an external constraint and a significant part of the elastic body is in contact with a stiff constraining surface. The research work presented in this doctoral dissertation formulates a computational model for the solution of elastic rods constrained inside or around frictionless tube-like surfaces. The segmentation strategy adopted to cope with this complex class of problems consists in sequencing the global problem into, comparatively simpler, elementary problems either in continuous contact with the constraint or contact-free between their extremities. Within the conventional Lagrangian formulation of elastic rods, this approach is however associated with two major drawbacks. First, the boundary conditions specifying the locations of the rod centerline at both extremities of each elementary problem lead to the establishment of isoperimetric constraints, i.e., integral constraints on the unknown length of the rod. Second, the assessment of the unilateral contact condition requires, in principle, the comparison of two curves parametrized by distinct curvilinear coordinates, viz. the rod centerline and the constraint axis. Both conspire to burden the computations associated with the method. To streamline the solution along the elementary problems and rationalize the assessment of the unilateral contact condition, the rod governing equations are reformulated within the Eulerian framework of the constraint. The methodical exploration of both types of elementary problems leads to specific formulations of the rod governing equations that stress the profound connection between the mechanics of the rod and the geometry of the constraint surface. The proposed Eulerian reformulation, which restates the rod local equilibrium in terms of the curvilinear coordinate associated with the constraint axis, describes the rod deformed configuration by means of either its relative position with respect to the constraint axis (contact-free segments) or its angular position on the constraint surface (continuous contacts.) This formulation circumvents both drawbacks that afflict the conventional Lagrangian approach associated with the segmentation strategy. As the a priori unknown domain, viz. the rod length, is substituted for the known constraint axis, the free boundary problem and the associated isoperimetric constraints are converted into a classical two-point boundary value problem. Additionally, the description of the rod deflection by means of its eccentricity with respect to the constraint axis trivializes the assessment of the unilateral contact condition. Along continuous contacts, this formulation expresses the strain variables, measuring the rod change of shape, in terms of the geometric invariants of the constraint surface, and emphasizes the influence of the constraint local geometry on the reaction pressure. Formalizing the segmentation strategy, a computational model that exploits the Eulerian formulation of the rod governing equations is devised. To solve the quasi-static deflection of elastic rods constrained inside or around a tube-like surface, this computational model identifies the number of contacts, their nature (either discrete or continuous), and the rod configuration at the connections that satisfies the unilateral contact condition and preserves the rod integrity along the sequence of elementary problems. [less ▲]

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See detailIntegrating roots into a whole-plant map of flowering-time gene networks in Arabidopsis thaliana
Bouché, Frédéric ULg

Doctoral thesis (2015)

Flowering is a crucial step in plant development that needs to be carefully regulated to occur at the right time of the year, thus ensuring reproductive success. In Arabidopsis thaliana, several ... [more ▼]

Flowering is a crucial step in plant development that needs to be carefully regulated to occur at the right time of the year, thus ensuring reproductive success. In Arabidopsis thaliana, several interconnected molecular networks have been disclosed that mediate flowering response to environmental cues, such as photoperiod and temperature, or to endogenous factors, such as plant age or hormones. Many of these signalling pathways are systemic, i.e. involve regulatory mechanisms distant from the shoot apical meristem where floral transition eventually occurs. However, most investigations were focused on the aerial parts of the plant but ignored the roots. The aim of this Ph.D. thesis was to integrate the roots into a comprehensive overview of the genetic control of flowering in Arabidopsis. A prerequisite was to obtain a full list of known flowering-time genes. This step led to the creation of a database of flowering-time genes, which is accessible online and in which users can navigate through data tables or interactive schemes (www.flor-id.org). In the second part of the work, we studied the involvement of the roots in the differential developmental rates of plants grown in hydroponics and on soil. In the third part of the work, we used data mining analyses to show that about 200 flowering-time genes are expressed in the roots of Arabidopsis. Using a complementary approach, we analysed the root transcriptome to identify early changes occurring during the induction of flowering by a photoperiodic treatment. Collectively, the results presented in this work brought new insights in the regulation of flowering time at the whole-organism scale by integrating the “hidden part” of plants in the current landscape of the molecular processes controlling phase transitions in Arabidopsis thaliana. [less ▲]

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See detailLong-term study of methane and two of its derivatives from solar observations recorded at the Jungfraujoch station
Bader, Whitney ULg

Doctoral thesis (2015)

A long-term study of methane and two of its derivatives, i.e. ethane and methanol from ground-based FTIR solar observations recorded at the high alpine International Scientific Station of the Jungfraujoch ... [more ▼]

A long-term study of methane and two of its derivatives, i.e. ethane and methanol from ground-based FTIR solar observations recorded at the high alpine International Scientific Station of the Jungfraujoch (3580 m a.s.l.) is reported. Those three gases act as tropospheric ozone precursors through their removal pathway and therefore have an impact on air quality. In the stratosphere, methane influences the content of ozone and in the production of water vapor. Moreover, both methane and ethane impact the greenhouse radiative forcing. While the latter is an indirect greenhouse gas because of its sinks, the former is the second most important anthropogenic greenhouse gas after CO2. The primary challenge of this work is the development and optimization of retrieval strategies for the three studied gases from FTIR spectra recorded at the Jungfraujoch station, in the framework of the Network for Detection of Atmospheric Composition Change (NDACC), in order to assess their concentrations in the atmosphere and to study their long-term trend and recent changes as well as their seasonal variations. The development and optimization of a retrieval strategy, based on the selection of the best combination of parameters, aims to limit interferences, minimize residuals, and maximize information content. To this end, the best retrieval strategy has been selected from a great number of available combinations thanks to a method for error analysis developed through this work. A 17-year time series of methanol is presented thanks to the combination of spectral windows for the first time for ground-based observations resulting in the improvement of the information content. We therefore present the first long-term time series of methanol total, lower tropospheric and upper tropospheric–lower stratospheric partial columns. We found no significant long-term trend of methanol but its seasonal cycle shows a high peak-to-peak amplitude of ̴103 % for total columns characterized by minimum values in winter and maximum values during summertime. The presented time series provides a valuable tool for model and satellite validation and complement the few NDACC measurements at northern mid-latitudes. Regarding ethane, we have for the first time included a combination of improved spectroscopic parameters as well as an improved a priori state that substantially reduce fitting residuals and enhance information content. Analysis of the long-term trend of ethane covering 20 years of observations revealed a strong positive trend of ethane from 2009 onwards of ̴5 %/year. We hypothesize that this recent ethane upturn may be the result of a large increase in fugitive emissions from the massive exploitation of shale gas and tight oil reservoirs on the North American continent. Finally, we quantified the changes of methane since 2005 from 10 ground-based NDACC sites, with a mean global increase of 0.30 %/year. Investigations into the source(s) responsible for this re-increase are performed with a GEOS-Chem tagged simulation that provides the contribution of each emission source and one sink to the total methane simulated. From the analysis of the GEOS-Chem tracers on both the local and global scales, we determined that the increasing anthropogenic emissions such as coal mining, gas and oil transport and exploitation, have played a major role in the increase of atmospheric methane observed since 2005 while they are secondary contributors to the total methane budget. [less ▲]

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See detailPolyphosphosphoesters for the design of organic and inorganic drug delivery systems
Ergül, Zeynep ULg

Doctoral thesis (2015)

Polymers with repeating phosphoester linkages in the backbone are biodegradable and emerged as a promising class of novel biomaterials, especially in the field of drug delivery systems. The pentavalency ... [more ▼]

Polymers with repeating phosphoester linkages in the backbone are biodegradable and emerged as a promising class of novel biomaterials, especially in the field of drug delivery systems. The pentavalency of the phosphorus atom offers a large diversity of structures and as a consequence a wide range of properties for these materials. The thesis focused on the synthesis of novel well-defined diblock copolymers made of one hydrophilic polyethylene oxide (PEO) block and one polyphosphotriester (PPE) block bearing unsaturations as side-group, as a platform for the design of advanced drug delivery systems. Firstly, novel alkenyl PEO-b-PPE amphiphilic copolymers were self-assembled in water, taking profit of the unsaturations to prepare core cross-linked micelles. Doxorubicin could be successfully loaded by impregnation in these micellar nanocarriers leading to improved stability and loading as compared to the corresponding non-cross-linked systems. Besides, the alkynyl and allyl unsaturations of PEO-b-PPE copolymers were used to prepare novel double hydrophilic block copolymers exhibiting calcium complexation capabilities. They were found quite efficient as template for the formation of calcium carbonate particles providing particles of unprecedented small size, and high size homogeneity. The use of a supercritical carbon dioxide process with carboxylic acid containing copolymers allows reaching CaCO3 particles about 1.5 µm. Finally, we demonstrate that adding lysozyme to the process allows encapsulation of this enzyme into the CaCO3 carriers, the protein activity being better preserved by using the PPE-b-PEO as compared to more conventional hyaluronic acid as a template. [less ▲]

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See detailLes portails occidentaux de la cathédrale d'Amiens
Lekane, Marie ULg

Doctoral thesis (2015)

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See detailMise au point d'un biomatériau à base de chitosan pour le traitement de l'arthrose
Oprenyeszk, Frédéric ULg

Doctoral thesis (2015)

L'arthrose est une pathologie dont la prévalence est élevée avec un retentissement socioéconomique important. À ce jour, les traitements de l’arthrose sont essentiellement symptomatiques. Le remplacement ... [more ▼]

L'arthrose est une pathologie dont la prévalence est élevée avec un retentissement socioéconomique important. À ce jour, les traitements de l’arthrose sont essentiellement symptomatiques. Le remplacement de l'articulation arthrosique par une prothèse est réservé aux formes les plus évoluées de la maladie. Dans ce contexte, il existe un réel besoin de nouveaux traitements bien tolérés et capables de prévenir ou de retarder la progression de la maladie. Dans ce but, nous avons développé des nouveaux biomatériaux sous la forme de billes ou d'hydrogel composés de chitosan d'origine non animale. Dans la première partie de ce travail, nous avons étudié in vitro le comportement des chondrocytes humains, provenant de cartilage arthrosique, incorporés dans des billes de chitosanalginate. Nous avons mesuré la quantité de médiateurs pro-infl ammatoires, cataboliques et anaboliques produite par les chondrocytes. Dans la deuxième partie, nous avons étudié les effets des billes de chitosan-alginate, injectées dans l’articulation, sur la progression de l’arthrose induite chez le lapin par section du ligament croisé antérieur. In vitro, nous avons mis en évidence les effets bénéfi ques et prometteurs des billes de chitosanalginate sur le métabolisme des chondrocytes humains arthrosiques. Dans ces conditions, ils produisaient moins de médiateurs infl ammatoires et cataboliques tout en maintenant la synthèse de composants spécifi ques de la matrice du cartilage. L'étude chez le lapin a montré que l’injection des billes de chitosan-alginate dispersées dans un hydrogel de chitosan prévenait le pincement de l’interligne articulaire - évalué sur une radiographie standard - et réduisait de façon signifi cative la gravité des lésions histologiques du cartilage ainsi que la synovite. En conclusion, la bille de chitosan-alginate est une matrice intéressante pour la thérapie cellulaire des lésions du cartilage et représente une alternative à l’acide hyaluronique pour la viscosupplémentation. [less ▲]

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See detailLa gouvernance environnementale au Sri Lanka. Discours, mise en oeuvre et appropriation locale des politiques de conservation de la nature dans le district d'Hambantota.
Rosillon, Caroline ULg

Doctoral thesis (2015)

L’approche développée dans cette thèse se situe dans le champ de l’anthropologie politique. Elle ambitionne de conjuguer une approche foucaldienne et les outils de la socioanthropologie du développement ... [more ▼]

L’approche développée dans cette thèse se situe dans le champ de l’anthropologie politique. Elle ambitionne de conjuguer une approche foucaldienne et les outils de la socioanthropologie du développement au sein d’une étude des politiques de développement et de conservation de la nature menées dans le district d’Hambantota, au sud du Sri Lanka. La première partie de la thèse se penche, dans une perspective historique et nationale, sur le cadre politique, discursif et idéologique dans lequel prennent place les programmes étatiques de développement. Il y est principalement question de l’émergence et de l’affirmation du nationalisme cinghalais bouddhiste qui s’est constitué au cours de l’histoire de la formation de l’État postcolonial. Le contenu de ce nationalisme repose sur une glorification du passé précolonial du pays et place la communauté paysanne au cœur de la nation. C’est dans ce cadre national que sont élaborés des programmes de développement à destination des populations rurales dont le contenu repose sur l’idée que la modernisation et le développement passent par la réactivation et la valorisation des traditions et du passé. Dans ce nationalisme cinghalais bouddhiste, la nature, dépositaire des traces de l’histoire nationale « légitime », occupe une place de premier plan et les aires protégées constituent des lieux d’expression, de matérialisation et de popularisation de l’idéologie nationaliste. La thèse met en avant la prégnance de cette idéologie dans la société sri lankaise, son caractère hégémonique et le rôle des espaces et de la nature comme supports de cette idéologie. La deuxième partie consiste en une approche ethnographique de deux études de cas illustrant les politiques de conservation mises en œuvre dans le district d’Hambantota. Il s’agit de deux programmes distincts dans leur nature, leur origine, leurs conséquences et la manière dont ils sont appropriés par les acteurs locaux. Le premier cas est un programme de conservation des tortues de mer conduit par une ONG locale dans un village de pêcheurs (Kandura). Le second cas est celui d’une aire protégée de l’État : le parc national de Bundala. La thèse essentielle développée dans cette partie est que les politiques de conservation ou de développement sont toujours influencées par un ensemble de contingences locales qui résultent d’une histoire et de dynamiques contemporaines et qui conditionnent les résultats des politiques implantées. Dans les deux exemples, il existe des formes de détournements, de dérives et de décalages décrits dans cette thèse à travers les processus d’« appropriation » dont font l’objet les deux programmes dans les localités dans lesquelles ils sont implantés. Ces interventions extérieures mettent en jeu un ensemble de rapports de force liés aux arènes locales dans lesquelles elles sont implantées qui sont elles-mêmes structurées en fonction de multiples réseaux de pouvoir et règles d’organisation. L’analyse comparative de ces deux études de cas révèle d’importants contrastes. Elle met en lumière des marges d’appropriation distinctes entre les deux programmes. Dans l’un, l’omniprésence de l’État ainsi que la verticalité du dispositif laisse peu de place aux formes de réappropriation collective ou individuelle tandis que la nature du projet, dans le second cas, permet aux individus des formes d’appropriation multiples et étendues. Ces contrastes sont liés à des types de pouvoir et de sociabilité distincts et témoignent de l’existence de multiples « faces » de la citoyenneté et de multiples registres de subjectivation dans lesquels les individus se construisent quotidiennement en fonction des situations dans lesquelles ils sont projetés. Cette thèse permet en définitive de saisir les processus locaux et tangibles de la gouvernance environnementale et offre une contribution singulière à l’étude des politiques néolibérales de la conservation de la nature. [less ▲]

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See detailBioremédiation du biphényle par Rhodococcus erythropolis T902.1 en présence de nanoparticules métalliques encapsulées dans une matrice de SiO2
Wannoussa, Wissal ULg

Doctoral thesis (2015)

La souche Rhodococcus erythropolis dégrade plusieurs types d’hydrocarbures (aliphatiques, cycliques et aromatiques). Ces derniers, notamment les hydrocarbures aromatiques, présentent des propriétés ... [more ▼]

La souche Rhodococcus erythropolis dégrade plusieurs types d’hydrocarbures (aliphatiques, cycliques et aromatiques). Ces derniers, notamment les hydrocarbures aromatiques, présentent des propriétés physico-chimiques particulières. En effet, ils sont très stables, peu volatils et hydrophobes. Ces propriétés les rendent relativement résistants à la bioremédiation. De ce fait, ils persistent dans l’environnement et causent des effets néfastes, comme les mutations génétiques, les cancers…., sur les êtres vivants. Dans ce travail, le biphényle a été choisi comme modèle en raison de son utilisation, à l’heure actuelle, comme matière de base pour la synthèse de composés polychlorobiphényles (PCB), comme additifs dans certaines formulations de pesticides etc. Cependant, la bioremédiation du biphényle est assez lente, ce qui nécessite encore de nombreuses investigations en vue d’améliorer les performances des microorganismes impliqués. De nombreux travaux mentionnés dans la littérature ont portés sur l’amélioration de la bioremédiation des polluants par l’utilisation d’éléments métalliques tel que le palladium, nickel, cobalt ou le fer à faible concentration. Leur utilisation pose cependant trois problèmes majeurs au niveau (i) de la séparation de ces adjuvants/catalyseurs des produits finaux (e.i. en traitement d’eau); (ii) du recyclage de ces composés et (iii) du pH du milieu réactionnel étant donné son impact majeur sur la solubilité des métaux. Pour limiter ces inconvénients, les catalyseurs métalliques peuvent être dispersés sur un support inerte et poreux de type Al2O3, SiO2, TiO2 offrant une surface spécifique suffisamment importante pour assurer une bonne dispersion des métaux sous forme de particules de taille nanométrique. Dans mes travaux, les nanoparticules métalliques (2 à 3 nm) encapsulées au sein d’une matrice de silice (10 à 20 nm) ont été réalisées. Ces dernières ont été synthétisées par le procédé sol-gel qui assure ainsi la stabilité de la réactivité du catalyseur (absence d’agglomération, relargage contrôlé…..). Les résultats expérimentaux ont montré que, les nanoparticules métalliques encapsulées (le fer, le cobalt et le palladium) activent la bioremédiation du biphényle. En outre, cet impact positif augmente avec la concentration des nanoparticules testées: le pourcentage de bioremédiation passe de 75 ±6.3 % en présence de 10-6M en nanoparticules de fer (Fe/SiO2) à 90 ±3.5 % en présence de 10-4 M après 18 jours d’incubation dans un milieu de culture relativement pauvre (milieu 284) contenant comme seul substrat carboné 500 ppm de biphényle. D’autre part, l’ajout à une concentration de 10-4 M en nanoparticules de fer (Fe/SiO2) ou cobalt (Co/SiO2) a stimulé l’activité des enzymes 1,2-catéchol dioxygénases susceptibles d’être impliquées dans la bioremédiation du biphényle. En outre, la présence de 10-4 M de nanoparticules en fer (Fe/SiO2) pourrait avoir un effet sur la production des biosurfactants notamment des glycolipides contenant du tréhalose. Ces derniers pourraient favoriser la solubilisation des hydrocarbures ou leur adhésion à la surface de la Rhodococcus erythropolis T902.1. En effet, la présence d’une concentration de 10 -4 Ce travail se termine par une discussion générale mettant en évidence les avantages d’utilisation des nanoparticules et une comparaison avec les études récemment publiées dans la littérature scientifique. Des perspectives de recherches sont soulevées afin de permettre une extrapolation de la bioremédiation d’autres polluants avec d’autres souches bactériennes en présence des nanoparticules. M des nanoparticules en fer (Fe/SiO2) induit une augmentation de 85 % en tréhalose. [less ▲]

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See detailHydro-mechanical analysis of the fracturing induced by the excavation of nuclear waste repository galleries using shear banding
Pardoen, Benoît ULg

Doctoral thesis (2015)

The long-term management of high-level nuclear wastes is envisaged by deep geological repository. Due to the safety function of the host formation, the behaviour of the Excavation Damaged Zone (EDZ) that ... [more ▼]

The long-term management of high-level nuclear wastes is envisaged by deep geological repository. Due to the safety function of the host formation, the behaviour of the Excavation Damaged Zone (EDZ) that develops around underground galleries during their drilling is of paramount importance. The EDZ is dominated by fracturing process which engenders irreversible modifications of the hydro-mechanical properties of the porous rock. In this zone, a significant hydraulic permeability increase of several orders of magnitude is observed. It may alter the safety function of the host formation by creating preferential flow paths for the migration of radionuclides towards the biosphere. Consequently, the understanding and the prediction of the EDZ hydro-mechanical behaviour are crucial issues for the long-term management of nuclear wastes. Among the different low-permeability media that are envisaged for the deep repository, the Callovo-Oxfordian claystone is studied. The fracturing behaviour, the water transfers, and the coupled processes that occur around the underground galleries are most particularly addressed, especially in the EDZ. The fractures induced by the excavation process are reproduced with strain localisation in shear bands. An appropriate model allowing to properly reproduce the strain localisation in geomaterials with finite element methods is used. It is an enhanced model for microstructure media called the coupled local second gradient model and which involves a regularisation method. Its application is extended to unsaturated anisotropic rocks with compressible solid grains. The numerical modelling of the fractured zone with shear banding provides information about its shape, extent, fracturing structure, and behaviour that are in good agreement with in situ measurements. In particular, the shape of the EDZ in the Callovo-Oxfordian claystone is governed by its anisotropy and the gallery convergence strongly depends on the appearance of the shear bands. The fluid transfers and the coupled processes are investigated in the EDZ. The impact of the rock fracturing on its hydraulic properties is addressed by taking into account strain localisation effects at macroscale. The evolution of the intrinsic water permeability is expressed by a strain-dependent relation which engenders a more pronounced increase of the permeability inside the shear bands. In agreement with experimental measurements, an important increase is reproduced in the excavation damaged zone. After gallery excavation, the hydraulic transfers in the rock surrounding the galleries are investigated by considering the interaction between the rock and the gallery air. These transfers are studied at large-scale during the reproduction of gallery air ventilation. Depending on the air hygrometry, the gallery ventilation implies drainage and desaturation of the surrounding rock which affect the shear banding development. The hydraulic transfers in the rock which depend on the water exchanges at gallery wall are also studied. The proposed approach aims to highlight the important hydro-mechanical aspects to take into account for the reproduction of the EDZ behaviour in unsaturated biphasic media with shear banding. The focus is resolutely on the large-scale numerical modelling of the EDZ as well as on the reproduction of the mechanical and hydraulic experimental measurements performed around galleries. [less ▲]

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See detailUsing remote sensing (optical and radar) and modeling to support the irrigation management of cereals in a semi-arid region: a case study of the Tadla irrigated perimeter in Morocco
Benabdelouahab, Tarik ULg

Doctoral thesis (2015)

Summary Irrigated agriculture is an important strategic sector in Morocco, it accounts for about 45%, on average, of the agricultural Gross Domestic Product, contributing thus to food security and ... [more ▼]

Summary Irrigated agriculture is an important strategic sector in Morocco, it accounts for about 45%, on average, of the agricultural Gross Domestic Product, contributing thus to food security and employment. It occupies 15% (about 1.5 million ha) of the total cultivated area in the country. Irrigation scheme managers need to ensure that water is optimally used in the irrigated perimeters and that water shortages are avoided. For large areas under irrigation, this can be achieved through water monitoring at plot level using modeling and satellite-based methodologies. The main objective of this research was to assess the use of optical and radar remote sensing and of crop modeling in the irrigation monitoring and management of wheat in the irrigated perimeter of Tadla. The potential of spectral indices derived from SPOT-5 images was explored for comparing, quantifying and mapping surface water content changes at regional and local levels. Indices were computed using the reflectance in red, near infrared and shortwave infrared bands. Our findings show that the normalized difference water index (NDWIRog) could be used to estimate and map the surface water content of wheat plots, from bare soil to fully covered soil. Backscatter threshold values derived from SAR images were used to detect irrigation water supplies in wheat plots and the optimal acquisition frequency of SAR images was determined in order to ensure continuous monitoring. A field crop model (AquaCrop) was adjusted to simulate durum wheat yields and the temporal evolution of soil moisture status in order to manage and schedule irrigation water supplies and assess their impact on yield. Currently, the approaches described in this paper are being applied independently. This research was intended, therefore, to provide tools to help policy-makers and stakeholders improve irrigation monitoring and mitigate wheat water stress at the field and irrigation perimeter levels in semi-arid areas. Keywords: irrigation management, spectral index, wheat, backscattering, SAR, semi-arid, Morocco. [less ▲]

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