References of "Doctoral thesis"
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See detailModel polyQ proteins based on the beta-lactamase BlaP: How non-polyQ regions influence the polyQ length-dependent aggregation process
Huynen, Céline ULg

Doctoral thesis (2015)

Neurodegenerative amyloid diseases are fatal disorders representing an important human health and economic burden. Amongst them, nine disorders are classified as polyglutamine (polyQ) diseases, for which ... [more ▼]

Neurodegenerative amyloid diseases are fatal disorders representing an important human health and economic burden. Amongst them, nine disorders are classified as polyglutamine (polyQ) diseases, for which no treatment is yet available. They are all characterized by the pathological expansion of a poly(CAG) sequence, above a specific threshold, within the coding sequence of nine unrelated genes, translated in nine polyQ proteins. The polyQ expansion, the only common point, is the critical determinant for polyQ disease development by triggering protein aggregation into amyloid fibrils. More recent studies however indicate that the protein context modulates the polyQ-induced aggregation process and the disease phenotype. The objectives of my thesis are to deeper investigate the molecular determinants of the complex interplay between the propensity of the polyQ tract to trigger protein aggregation and the modulating role of non-polyQ regions in order to allow the identification of strategies to interfere with the pathological aggregation process. For that purpose, model polyQ proteins, referred to as BlaP-polyQ chimeras, based on the β-lactamase BlaP and polyQ sequences (23 – 79Q) inserted at two positions (197, in between or not unstructured peptides, or 216), are used and their aggregation properties are characterized under several conditions. We first observe that the polyQ length is determinant for BlaP-polyQ chimera aggregation. Indeed, there is a Q-threshold for the aggregation into amyloid fibrils and for fibril elongation. Above this threshold, the aggregation in solution and the elongation rate increase with the length of the polyQ tract, with an exponential rise-to-maximum and a linear regression, respectively, independently of the conformation of the BlaP moiety, and of the position of the polyQ tract within BlaP. Longer polyQ tracts are likely to have a larger conformational flexibility allowing them to more easily adopt an amyloid-aggregation prone conformation. However, the Q-threshold for fibril elongation is much lower than for fibril formation in solution: the polyQ tract requires a larger conformational flexibility to nucleate the formation of fibrils than to elongate them. Secondly, the Q-threshold for fibril formation is lower once the BlaP moiety is unfolded, and BlaP-polyQ chimeras aggregate faster into amyloid fibrils under conditions favoring the unfolding of the BlaP moiety. The native structure of BlaP is likely to impose conformational constraints to moderate and long polyQ tracts that block and decrease, respectively, their propensity to form fibrils. The effects of constraints decrease with the polyQ length. Thirdly, BlaP chimeras with the polyQ tract in position 216 have an increased propensity to trigger the nucleation and the elongation of amyloid fibrils compared to chimeras with the polyQ in position 197. Advanced studies confirm that the propensity of the polyQ tract to aggregate into amyloid fibrils is linked to the conformational flexibility of the polyQ tract, which depends on (i) the polyQ length, (ii) the location of the polyQ tract within BlaP, i.e., a terminal location or embedded within a protein domain, and (iii) the structural properties of the polyQ flanking regions. Finally, we observe that the whole region flanking the polyQ tract in position 197 at its N-terminus has an anti-aggregating property that fully counterbalances the pro-aggregating property of that flanking at the C-terminus. The former imposes strong conformational constraints to the polyQ tract that reduce its conformational flexibility and hence its aggregation propensity. Moreover, these regions are likely to differently affect the solubility of the polyQ protein and hence the driving force for insoluble aggregation. Altogether, our data also suggest that BlaP chimeras aggregate via the commonly described nucleation-dependent polymerization mechanism during which the aggregation is first triggered by polyQ-polyQ interactions, and then a subsequent slight reorganization of the BlaP moiety is required for conversion of aggregates into amyloid fibrils. Based on these results, we should allow the development of therapeutic strategies, targeting specifically the molecular features of the complex interplay between the polyQ and non-polyQ regions during the nucleation and/or elongation of the pathological aggregation of polyQ proteins. [less ▲]

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See detailDevelopment of a new design method for the cross-section capacity of steel hollow sections
Nseir, Joanna ULg

Doctoral thesis (2015)

The cross-sectional behaviour of steel sections can be shown to be influenced by two extreme behaviors: the resistance and the instability. These boundaries are accounted for in current standards through ... [more ▼]

The cross-sectional behaviour of steel sections can be shown to be influenced by two extreme behaviors: the resistance and the instability. These boundaries are accounted for in current standards through a classification system consisting on rules depending on the cross-section dimensions. For example, in EN 1993-1-1, classes are defined spanning from stocky sections (class 1) able to develop their full plastic capacity, to slender sections (class 4) for which the effective properties are used with the use of the effective width method (EWM). However, for cold-formed steel sections, characterized by a non-linear material law, the cross-section resistance can go beyond its plastic capacity due to strain hardening effects. Moreover, with the emergence of high strength steel (i.e. cross-sections falling into class 4) and more complex cross-section shapes, the effective width method is becoming too complicated. Many other reasons and discrepancies are making the cross-section classification too complex and inconsistent. The Overall Interaction Concept (OIC) stands as a new design approach that aims at a straightforward design check of the stability and resistance of steel cross-sections. Based on the use of a generalized relative slenderness and so-called interaction curves, it can be applied to any type of cross-section, further includes potential non-linear material behaviour and covers combined loading cases. The main aim of this thesis is to develop and propose OIC interaction curves dedicated to steel hollow sections subjected to various load cases. A test program was carried out as a part of a European project named ‘HOLLOPOC’ to investigate the cross-sectional behavior of cold-formed hot-finished and hot-rolled square, rectangular and circular sections. 57 cross-sections tests including simple and combined load cases were performed. Besides, a finite element model was developed and calibrated on the basis of the tests, and its accuracy was seen to be sufficient to subsequently undergo an extensive numerical parametric study for hot-rolled and cold-formed cross-sections, leading to over than 40 000 numerical results. Based on these computations, design proposals were made within the context of the Overall Interaction Concept, using an extension of the Ayrton-Perry approach. Finally, a validation of the proposed formulae was made through a comparison with existing approach and worked examples were presented, in order to illustrate (i) the application of the method and (ii) its benefits in comparison to application of current EC3 rules. [less ▲]

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See detailOrigine et dynamique des populations d’arbres des forêts denses humides d’Afrique Centrale, le cas de Lophira alata Banks ex Gaertn C.F. (Ochnaceae)
Biwole, Achille ULg

Doctoral thesis (2015)

The canopy of Central African rainforests is characterized by the abundance of light-demanding trees belonging to several species, suggesting that favorable conditions for their regeneration once ... [more ▼]

The canopy of Central African rainforests is characterized by the abundance of light-demanding trees belonging to several species, suggesting that favorable conditions for their regeneration once prevailed. Today this isn’t the case in light of the demographic structure of their populations, which shows a lack of regeneration. The appearance of such species in rainforests is the result of significant and sustainable openings in the forest canopy. Such events may have occurred with climatic changes and / or large-scale anthropogenic disturbances. The risk of their populations decline is increased by the fact that most of them are timber species. This is typically the case of Lophira alata Banks ex Gaertn C.F., which is one of the most important Central African trees harvested, and is considered vulnerable by the IUCN. In the current context where the preservation of the biodiversity and the integrity of the forest cover is a major concern, the present PhD aims to understand the history and ecological requirements of L. alata in order to propose the sustainable management strategies. The history of L. alata has been studied using an approach integrating both anthracology and archeology. We found a large body of evidences (pottery fragments, palm nuts and charcoal) in the forests soil of southern Cameroon indicating human occupation and widespread fires over two periods : 2200 - 1500 years BP, and around 300 years BP. The age of the most recent events coincides with the probable age of the tallest specimens of L. alata. To determine the light requirements of the species and to better define its regeneration strategy, a quantitative study on the guild of juveniles was conducted for two years. The results show that L. alata has both the characteristics of a pioneer species and those of a non-pioneer species. Indeed, at low irradiances (1% of full sunlight), the plants mortality rate was very low and their biomass showed no signs of decline, a behavior observed in all non-pioneer species. By contrast, the response of leaf traits, patterns of biomass allocation, and the maximum growth of plants in the intermediate (23-43% of the relative irradiance) and high (100%) irradiance levels, according to the population origins, are typical of all pioneer species. These results emphasize the importance of the population origins when studying the response to light and the need to define a more encompassing classification system. In terms of the dynamics of mature populations, environmental conditions affect the diameter growth of trees, with better growth being realized in the evergreen forest. Nevertheless, even under these favorable conditions, simulations of the exploitable stocks and their recovery rates indicated a significant decline during the first three cutting cycles, which could lead to a decline in economic activity associated with this species. Our results allowed us to suggest a set of recommendations for the sustainable management of L. alata. [less ▲]

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See detailL'activité de la NADPH oxydase : une nouvelle cible pour la curcumine ?
Derochette, Sandrine ULg

Doctoral thesis (2015)

La NADPH oxydase (Nox2) des neutrophiles (PMNs) est une enzyme multi-protéique responsable de la production d'espèce activées de l'oxygène (ROS) pour la destruction des pathogènes. L'activation excessive ... [more ▼]

La NADPH oxydase (Nox2) des neutrophiles (PMNs) est une enzyme multi-protéique responsable de la production d'espèce activées de l'oxygène (ROS) pour la destruction des pathogènes. L'activation excessive des PMNs est souvent associée à des pathologies mortelles chez le cheval, faisant de l'activité de la Nox2 une cible thérapeutique privilégiée. Le premier but de ce travail, a été de développer une méthode appelée "cell-free system" (CSF) pour mesurer l'activité in vitro de la Nox2 équine. Un inconvénient de cette technique sont les interférences possibles entre les inhibiteurs et la sonde utilisée pour la mesure de l'activité. Sur base de notre CFS, nous avons créé l'EquiNox2, un nouvel outil pharmacologique, pour étudier les interactions entre des inhibiteurs et la Nox2 et leurs effets sur l'assemblage et l'activité de l'enzyme. Cette méthode consiste en la mesure in vitro de l'activité de la Nox2 fixée sur un support solide, ce qui permet d'éliminer les inhibiteurs avant la mesure de l'activité et réduit les interférences citées pour le CFS. Le CFS et l'EquiNox2 ont été validés avec le diphénylène iodonium et le Gp91ds-tat, deux inhibiteurs connus de la Nox2 humaine. Le deuxième but de ce travail, était l'étude du NDS27, un complexe de lysinate de curcumine avec l'hydroxypropyl-β-cyclodextrine (HPβCD) sur la réponse oxydante des PMNs. Le NDS27, n'est pas toxique et est capable d'entrer et d'interagir avec les membranes des PMNs et d'inhiber l'activité de la myéloperoxydase, la Nox2 et la PKCδ (un activateur de Nox2) impliquées dans la production de ROS. Nous avons montré en CFS et EquiNox2 que le NDS27 se fixe fortement à la Nox2 pour empêcher son assemblage et que l'HPβCD, l'excipient du NDS27, en plus de solubiliser et transporter la curcumine, augmente l'action de celle-ci sur les activités de la PKC et la Nox2. L'effet modulateur du NDS27 sur l'activation de la Nox2 ouvre des perspectives thérapeutiques pour traitement des pathologies accompagnées de réactions inflammatoires excessives. [less ▲]

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See detailEtude de la sémaphorine virale codée par le gène A3 de l’herpèsvirus alcélaphin 1
Myster, Françoise

Doctoral thesis (2015)

Among gammaherpesvirus, the Macavirus genus is composed of viruses associated to malignant catarrhal fever (MCF) and other phylogenetically related viruses. MCF is a frequently fatal lymphoproliferative ... [more ▼]

Among gammaherpesvirus, the Macavirus genus is composed of viruses associated to malignant catarrhal fever (MCF) and other phylogenetically related viruses. MCF is a frequently fatal lymphoproliferative disease. Three macaviruses inducing MCF have been entirely sequenced: alcelaphine herpesvirus 2 (AlHV-2), ovine herpesvirus 2 (OvHV-2) and alcelaphine herpesvirus 1 (AlHV-1). Sheep carries OvHV-2 asymptomatically while wildebeest is infected with AlHV-1 without developing any clinical signs or lesions. Both viruses represent the most studied macaviruses. In susceptible ruminants, OvHV-2 and AlHV-1 induce the sheep-associated form and the wildebeest-derived form of MCF (WD-MCF), respectively. Economic consequences of WD-MCF are significant in sub-Saharan Africa. WD-MCF is characterized by the proliferation and infiltration of lymphoblastoid T cells surrounding blood vessels and can be considered as a model for peripheral T cell lymphoma caused by a virus. Rabbits are used as experimental model to study MCF. This species develops clinical signs and lesions that they are indistinguishable from those observed in other susceptible species. Until recently, available data on WD-MCF pathogenesis were limited to the simple description clinical signs and lesions. Recently, it was demonstrated that CD8+ T cells proliferate and that this cellular expansion is associated with a severe increase of the viral load in PBMC and lymphoid organs (Dewals et al., 2008). The cloning of the AlHV-1 genome as an infectious and pathogenic bacterial artificial chromosome (BAC) has greatly facilitated the study of individual gene of AlHV-1 (Dewals et al., 2006). Among herpesviruses, viral semaphorins can only be found in members of the Macavirus genus. OvHV 2 encodes Ov3, and AlHV-2 and AlHV-1 encode A3, both genes encoding a semaphorin homolog. Semaphorins are proteins characterized by a conserved amino-terminal domain, the SEMA domain. The roles of the semaphorins on cytoskeleton dynamics have been widely studied. Viral semaphorins could mediate immune evasion mechanisms or viral dissemination and could be involved in specific properties of macaviruses. The first study of the present thesis was dedicated to the investigation of the pathogenesis of WD-MCF and the role of latency. We investigated the distribution of the AlHV-1 infection in the lesions and demonstrated that the infiltration of CD8+ T cells in different lymphoid and non-lymphoid organs and tissues is directly associated with a non-productive viral infection. The second study focused on the A3 gene of AlHV-1 and its potential functions during WD-MCF. We showed that the A3 gene is expressed during the early phase of the viral infection and encodes a functional semaphorin that was termed AlHV-sema. AlHV-sema was able to induce cell retraction. Despite the observed independent acquisition of pox- and herpesvirus semaphorins, AlHV-sema inhibited phagocytosis by dendritic cells and migration to the draining lymph node through mechanisms similar to poxvirus semaphorin. AlHV-sema could also facilitate viral dissemination or confer immune evasion functions. Next, we investigated whether AlHV-sema could affect WD-MCF induction. We did not observe any effect of the absence of AlHV-sema expression during the development of WD-MCF after rabbit nasal infection. Macaviruses are swine and ruminant gammaherpesviruses responsible for a latent asymptomatic infection in their natural species. The development of MCF in other ruminant susceptible species is due to cross-species transmission. During evolution, the gene selection in susceptible species is certainly reduced due to the fact that these species are dead-end hosts. Thus, it is difficult to address the role of AlHV-1 specific genes in MCF as these genes have evolved in other species. Nevertheless, we brought in this work important insight for our understanding of the pathogenesis of WD-MCF and we identified AlHV-sema as a potential immunoevasion factor. DEWALS B., MYSTER F., PALMEIRA L., GILLET L., ACKERMANN M., VANDERPLASSCHEN A. Ex vivo bioluminescence detection of alcelaphine herpesvirus 1 infection during malignant catarrhal fever. J. Virol., 2011, 85, 6941-6954. MYSTER F., PALMEIRA L., SOREL O., BOUILLENNE F., DEPAUW E., SCHWARTZ-CORNIL I., VANDERPLASSCHEN A., DEWALS B.G. Viral semaphorin inhibits dendritic cell phagocytosis and migration but is not essential for gamma-herpesvirus-induced lymphoproliferation in malignant catarrhal fever. J. Virol., 2015. [less ▲]

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See detailSeagrass macrophytodetritus: a copepod hub - Species diversity, dynamics and trophic ecology of the meiofauna community in Posidonia oceanica leaf litter accumulations
Mascart, Thibaud ULg

Doctoral thesis (2015)

Macrophytodetritus is a heterogeneous mixture of detrital material that accumulates on submerged unvegetated sand patches amid vast Mediterranean Posidonia oceanica seagrass meadows. Several vagile ... [more ▼]

Macrophytodetritus is a heterogeneous mixture of detrital material that accumulates on submerged unvegetated sand patches amid vast Mediterranean Posidonia oceanica seagrass meadows. Several vagile invertebrates are present in substantial biomass and biodiversity. Among these invertebrates, meiofauna (fauna between 38µm and 1mm) is ubiquitous and seems to play a key-feature in this dynamic and patchy system. Coastal ecosystems are under the direct effect of anthropogenic disturbance and degradation. Extra research is crucially needed to understand better the dynamics of coastal vegetation, in order to have a more successful restauration of these regressing ecosystems. In this context, the main goal of this PhD research was triple: (1) characterising in situ the physico-chemistry and the composition of the macrophytodetritus accumulations in the Calvi Bay, Corsica, (2) identifying the diversity of the associated meiofauna communities, especially harpacticoid copepods together with unravelling the origin of the present copepods and (3) characterizing the trophic ecology of the copepod communities in the macrophytodetritus at the specific and eco-morphological level. This research showed that macrophytodetritus biomass is composed on average for 75% of dead P. oceanica seagrass leaves shed after senescence. Attached to the surface of the seagrass leaves numerous micro- and macroepiphytes are present, representing on average 10% of the total biomass. The remaining part is mainly constituted of drift material, like detached P. oceanica shoots and epilithic macroalgae. A seasonal pattern is observed regarding the amount of accumulated material and the physico-chemical composition inside the accumulation. Wind-induced hydrodynamics is the responsible driver behind the variability of the macrophytodetritus and consequently it has a major impact on the faunal communities already present in a macrophytodetritus accumulation. Previous studies showed that the presence of macrofaunal invertebrates (> 1 mm) in high amounts contributes to the degradation of the detritus. Similarly, this study proves the ubiquitous presence of meiofauna in macrophytodetritus. Depending on the season, densities from 20.10³ to 160.10³ meiofaunal organisms per square metre of accumulation were recorded. Copepods were the most abundant taxon (> 50%) of which 87% belonged to the order Harpacticoida. Nematodes were the second most abundant taxon, representing on average 18% of the total meiofauna densities. A total of 61 copepod species were found in Calvi Bay macrophytodetritus accumulations and adjacent habitats (bare sand, seagrass and water column), wherefrom 85% were shared amongst these habitats, underlining the high colonization capabilities of copepods. Active colonization occurred within 24h through species-specific dispersal pathways. Certain species were more avid to colonize, resulting in a colonizer-competitor trade-off among the copepod community. Eco-morphological characteristics seemed to be responsible for the dispersal potential. However, the variety of the composition of the copepod community suggested that other factors also contributed to the attractiveness of the structurally complex macrophytodetritus habitat. The isotopic niches of four abundant copepod species, representing four different eco-morphological groups were identified: Ectinosoma dentatum (mesopsammic-type), Diosaccus tenuiremis (phytal-type), Tisbe furcata (epibenthic-type) and Clausocalanus arcuicornis (water-column-type). Based on stable isotope analysis, fatty acid profiling and Bayesian mixing model, results suggested an interspecific diversity which would indicate a species-specific resource partitioning. C. arcuicornis mainly fed on suspended organic matter, while D. tenuiremis thrived mainly on epiphytes (mostly diatoms). E. dentatum was dependent on the seasonal availability of food sources, while T. furcata fed on a heterogeneous mixture of sources. Presumably none of the species directly assimilated dead seagrass leaf litter. Overall, by combining in situ sampling, novel mesocosm experiment, biomarkers and mixing models, this study displayed the carrying capacity of macrophytodetritus to support a large amount of meiofauna and a wide diversity of copepod species. The morphological differences among copepod species seem to allow specialization towards habitat preferences, (physical habitat preferences and colonization potential) and towards resource preferences (food partitioning). Macrophytodetritus seems thus to be a suitable home, or a temporary hub for a diverse copepod community. Finally, this dynamic and patchy habitat, prone to swift changes and situated at the crossing of different ecosystems, plays a major role in coastal ecology. [less ▲]

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See detailNouveaux modèles pour le calcul des roulements à billes cryotechniques
Servais, Christophe ULg

Doctoral thesis (2015)

The behavior of cryogenic ball bearings, that is to say those included in several space rocket engines, is quite difficult to estimate. The high speed effects, heavy loads and lack of conventional ... [more ▼]

The behavior of cryogenic ball bearings, that is to say those included in several space rocket engines, is quite difficult to estimate. The high speed effects, heavy loads and lack of conventional lubrication are among the main concerns during the conception phase. This doctoral thesis proposes a new numerical method to evaluate the way solid lubricated ball bearings are working. The main originality of the survey is the determination of the link between the ball/ring contacts and the rolling elements kinematics, for any kind of bearing loading or rotational speed. Moreover, the dissertation includes a mathematical model of the cage dynamics. The result of the whole exposed method is a computer program, which allows to deal with critical aspects of cryogenic ball bearings. Indeed, a set of examples demonstrates the capabilities of the new method as a design tool and provides a deep understanding of the specific features of such ball bearings. [less ▲]

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See detailFragmentation urbaine à travers les réseaux techniques
Cabrera Quispe, Juan Edson ULg

Doctoral thesis (2015)

Since about three decades ago, the networking services (water, energy, transport and telecommunications) are the subject of studies and mainly reforms (liberalization, privatization and concessions to ... [more ▼]

Since about three decades ago, the networking services (water, energy, transport and telecommunications) are the subject of studies and mainly reforms (liberalization, privatization and concessions to private companies, etc.) and also an important economic policy issue. However the possible effects of these reforms on the fragmentation or integration of urban societies are still poorly studied, although some studies (mainly on developing cities) support the thesis that there would be a growing urban fragmentation, reinforced by the dominant modes of implementing reforms network services. One of the most important theses about the subject is in a relatively recent development of the English authors Stephen Graham and Simon Marvin (2001). Their work generalizes the motion of fragmentation (splintering Urbanism) to all network services and a set of economic regions in the world. While this thesis presents consistency and validity - since it is known that the application of models of decentralization and liberalization of services has an effect on the fragmentation - the position of fragmentation due to centralized networks is inside a new analysis framework and still incomplete considering the absence of more empirical evidence. The thesis of fragmentation from centralized networks suggests that powerful factors are contributing to the disintegration of infrastructure, favoring the fragmentation of the social structure and material of cities. In fact, this breakdown of infrastructures makes possible many strategies of evasion; they are addressed to connect powerful users and valorized spaces, preventing the connection with less powerful users and poor spaces. These processes lead to the creation of spaces from different social networks, resulting in social elites living every day in places disconnected from the urban structure of the set (in gated communities, new complex people and other planned communities), as well as the lower classes, but the latter with the worst conditions. The main hypothesis of the "splintering Urbanism" argues that network services have an integrated character and are precisely the privatization and liberalization of services that contribute to the breakdown of network infrastructure and urban fragmentation feed. The control of networks from powerful coalitions of actors, separation and segmentation boost infrastructure in different network elements and service pack (2001: 141). This separation would occur across strategies "bypass" or "wrap" seeking to connect users, valuable or powerful places, and through discarding or dodge weaker users and worthless places. Our thesis "Urban Fragmentation through technical networks," confirms and reinforces the thesis made by Graham & Marvin, across expounding on the Cochabamba Bolivian context, a set of technical networks of small-scale or micro decentralized networks which are managed by autonomous social organizations that also fragment the territory without the need for "by pass" and the socio-spatial differentiation, but through the realization of strategies linked to autonomous administration and management of common and basic goods like water. This thesis demonstrates the existence of processes of spatial dislocation and loss of solidarity (main evils of urban fragmentation) across the dynamics of technical devices and decentralized networks infrastructure services from private-community water and small scale. However, our work describes in its urban development, territorial and environmental problems inside the phenomenon. The paper first presents a set of theories that attempt to explain the fragmentation and its particularities, then describes the socio-spatial formation of the study area whose characteristics allow this type of phenomenon, to arrive to a section that exposes all the particularities of the management water from public and local actors, analyzed from the environmental logic of urban water cycle, including the specifics of the main stage of study of this thesis, the municipality of Quillacollo in Cochabamba. From a spatial perspective, the thesis exhibits the characteristics of urban fragmentation across technical networks, exposing the details related to the organization of urban space as a result of processes of spatial dislocation, loss of solidarity and exercise of territoriality in small networks. It is concluded in a discussion about the validity of the strategies in terms of access to the resource, the possibilities of intervention and reflections about the power relationships among fragments and for water control. Finally, as a supplement, urban fragmentation through small technical networks, also allows to display the tensions between two ways of managing the territory (centralized view from the public sector and decentralized vision from local communities) highlighting the uncomfortable and marginalized urban planning position, but challenging the urbanism to recover to action on the highly fragmented contemporary cities with complex scenarios of governance and sometimes rare or endangered resources. [less ▲]

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See detailAnalytical strategies for ultra-trace measurement of dioxins and related compounds in biological matrices
L'Homme, Benjamin ULg

Doctoral thesis (2015)

The human exposure to persistent organic pollutants (POPs) is a concern since these compounds are ubiquitous in the environment. This class of compounds group different families such as the ... [more ▼]

The human exposure to persistent organic pollutants (POPs) is a concern since these compounds are ubiquitous in the environment. This class of compounds group different families such as the polychlorodibenzo-p-dioxins (PCDDs), the polychlorodibenzofurans (PCDFs), the polychlorinated biphenyls (PCBs), the organochlorine pesticides (OCPs), and the halogenated flame-retardants (HFRs). Their use, their release in the environment, their presence in foodstuffs, as well as in various goods on the market are mostly regulated through international conventions, like the Stockholm convention on POPs, and at the European and national levels. Despite the proactive approach in order to reduce the overall exposure to POPs, levels of contaminants (even banned) are still found in the environment and in the human body. In this thesis, we developed several methods of analysis of POPs in different samples. The first was a confirmatory method for PCDD/Fs and PCBs analysis in food and feed following a new European Regulation No 709/2014 that recently allowed the use of gas chromatography (GC) coupled to triple quadrupole mass spectrometry (GC-QQQMS/MS) for this purpose. We fully validated the method on vegetable oil matrix around the maximum level of 1.50 ng WHO2005TEQ/kg. We showed that all analytical criteria, specific to this instrumentation, laid down by the Regulation were met, which indicates that the QQQMS/MS can successfully be used in the legal context for confirmatory purposes and could be an alternative to high-resolution sector field mass spectrometry (HRMS) in this context. The proper establishment of limits of quantitation was a key point in the discussion along with other analytical criteria proposed in the European Regulation, as new interpretations were necessary for the use of triple quadrupole mass spectrometry due to its different features from the HRMS. In addition, we developed in parallel a method for the analysis of Dechloranes in food. The measurement of ultra-trace levels of compounds from this emerging class of flame-retardants was possible after optimization of the injections parameters by means of experimental design, and of fragmentation pathways. Eventually, we reported relatively low levels in various food matrices and preliminary data about the significance of this route of exposure for humans. Besides food analysis, we developed a screening method to quickly assess levels of contaminants in human blood, involving a minimally invasive sampling technique and a couple of drops of blood. The instrumentation was first based on cryogenic zone compression (CZC) hyphenated to high-resolution time of flight mass spectrometry (HRTOFMS) applied to the analysis of two markers of exposure in regular dried-blood spots (DBS) typically used for newborn sampling. The second approach was based on GC-QQQMS/MS applied to the analysis of a broader range of OCPs and NDL-PCBs (30 analytes) in 40 µL blood. The blood was however collected using a novel Volumetric Absorptive MicroSampling (VAMS) method, directly inspired by the DBS but offering a control on the volume of blood sampled, hence opening the door to quantitation. The sample preparation of the VAMS dried sample was miniaturized and only 2 mL of solvents were necessary to prepare a sample, which makes it environmentally friendly. The focus was especially drawn to maximize the sensitivity via the optimization of the ionization energy and the electron multiplier voltage in order to reach appropriate low limits of quantitation. In this context of ultra-low volume of blood, background levels arose as the limitation of the method owing to the small signals coming from samples and closing the gap with blanks. Nevertheless, this patient-friendly approach is perfectly suitable for fast screening of population and could be useful in the context of UNEP campaigns where samples are hardly collected. [less ▲]

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See detailLe confesseur du Prince dans les Pays-Bas espagnols (1598-1659): une fonction, des individus.
Pirlet, Pierre-François ULg

Doctoral thesis (2015)

Cette thèse envisage, à la cour de Bruxelles (1598-1659), les rapports entre les pouvoirs séculiers et religieux au travers de la figure nodale du confesseur du Prince.

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See detailArtificial Intelligence in Video Games: Towards a Unified Framework
Safadi, Firas ULg

Doctoral thesis (2015)

The work presented in this dissertation revolves around the problem of designing artificial intelligence (AI) for video games. This problem becomes increasingly challenging as video games grow in ... [more ▼]

The work presented in this dissertation revolves around the problem of designing artificial intelligence (AI) for video games. This problem becomes increasingly challenging as video games grow in complexity. With modern video games frequently featuring sophisticated and realistic environments, the need for smart and comprehensive agents that understand the various aspects of these environments is pressing. Although machine learning techniques are being successfully applied in a multitude of domains to solve AI problems, they are not yet ready to enable the creation of fully autonomous agent that can reliably learn to understand the environments found in complex video games. Since video game AI is often specifically designed for each game, video game AI tools currently focus on allowing video game developers to quickly and efficiently create specific AI. One issue with this approach is that it does not efficiently exploit the numerous similarities that exist between video games not only of the same genre, but of different genres too, resulting in a difficulty to handle the many aspects of a complex and realistic environment independently for each video game. These similarities, however, exist on a conceptual level. While video games do indeed share a variety of concepts, their interpretations vary from one game to another. Hence, these similarities can only be directly exploited at a conceptual level. Inspired by the human ability to detect analogies between games and apply similar behavior on a conceptual level, this thesis suggests an approach based on the use of a unified conceptual framework to enable the development of conceptual AI which relies on conceptual views and actions to define basic yet reasonable and robust behavior. Because conceptual AI is not tied to any game in particular, it benefits from a continuous development process as opposed to a development that is confined to the scope of a single game project. [less ▲]

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See detailSynthèse et applications catalytiques d'adduits zwitterioniques de carbènes N-hétérocycliques
Hans, Morgan ULg

Doctoral thesis (2015)

In 1991, Arduengo isolated and fully characterized the first N-Heterocyclic Carbene (NHC), thereby confirming the existence of these stable divalent carbon species postulated almost thirty years earlier ... [more ▼]

In 1991, Arduengo isolated and fully characterized the first N-Heterocyclic Carbene (NHC), thereby confirming the existence of these stable divalent carbon species postulated almost thirty years earlier by Wanzlick. Since then, the enthusiasm for these highly nucleophilic and strongly basic compounds has steadily increased in the scientific community. Their reactivity with respect to organic compounds is very rich and is relatively well documented since the middle of the 1960’s. Their strong electron-donicity and their moderate pi-acidity make them almost universal ligands. NHC complexes have indeed been prepared with practically all the metals from the periodic table. Their high nucleophilicity also allowed to successfully employ them as organocatalysts. The state of the art in these three fields as well as the properties of NHCs and their electronic and steric characterizations are discussed in the introduction of this manuscript. The second chapter is devoted to the synthesis and characterization of imidazol(in)ium dithiocarboxylates (NHC•CS2 adducts), carboxylates (NHC•CO2 adducts) and thiocarboxylates (NHC•COS adducts) and to their applications in organic synthesis and in coordination chemistry. First, because NHC•CO2 adducts do not require any reagents to generate free carbenes in solution, we proposed them as precursors of NHC to promote various Michael additions. Preliminary catalytic assays of a set of five representatives of this zwitterion family in a carba-Michael addition previously reported in the literature highlighted the net superiority of 1,3 dicyclohexylimidazolium carboxylate (ICy•CO2). Subsequently, we showed the efficiency of our catalytic system to promote sulfa-, and phospha-Michael additions. Eventually, the same precatalyst showed efficiency to initiate various sulfa-Michael/aldol organocascades. Second, we looked at the synthesis of a representative set of five imidazol(in)ium thiocarboxylates. Their characterization indicated a probable loss of the thiocarboxylate group. Hence, we tested their efficiency as carbene’s precursors in two benchmark reactions usually catalyzed by NHCs. 1,3-Dicyclohexylimidazolium thiocarboxylate (ICy•COS) turned out to be most effective to promote transesterification/acetylation, while 1,3 bis(2,4,6-trimethylphenyl)imidazolinium thiocarboxylate (SIMes•COS) afforded a quantitative yield in the benzoin condensation. Moreover, reaction of NHC•COS betaines with a half-equivalent of ruthenium dimer [RuCl2(p-cymene)]2 led to [RuCl2(p-cymene)(NHC•COS)] complexes in which the zwitterions were bonded to ruthenium by the sulfur atom only. This is a remarkable result because NHC•CO2 zwitterions behaved like efficient NHC precursors leading to metal-NHC complexes, while imidazol(in)ium dithiocarboxylates showed no signs of dissociation. They behaved as kappa2-S,S’ chelating ligands and led to metal-(S2C•NHC) complexes. Finally, catalytic tests of these new complexes bearing NHC•COS adducts in the Ring-Opening Metathesis Polymerization (ROMP) of cyclooctene, in the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate and in the synthesis of enol esters resulted in low yields. However, they provided evidence for the rearrangement of the starting complexes in Ru-NHC species under the experimental conditions adopted. The third chapter is devoted to the synthesis of azolium enolates and their characterization, as well as their involvement in the Staudinger reaction and to their coordination chemistry to ruthenium. Our interest initially focused on the general mechanism of the NHC-catalyzed Staudinger reaction. Literature reports two plausible mechanisms for the [2 + 2] cycloaddition between ketenes and electron-poor imines. The first one, called "Imine-first" involves an azolium amide, while the second one, called "Ketene-first" goes through an azolium enolate. Synthesis and full characterization of these two types of zwitterionic adducts combined with their catalytic assay in the reaction between diphenylketene and N-tosylbenzaldimine allowed us to acquire a strong experimental evidence in favor of the "Ketene-first" observed path. We were then interested by probing the diastereoselectivity observed during NHC catalyzed [2 + 2] cycloadditions between unsymmetrical ketenes and various N sulfonylbenzaldimines. In order to investigate the parameters that influenced the stereoselectivity during these reactions, we prepared and fully characterized two new betaines (S)IMes•EtPhC=C=O and we performed catalytic assays in the reaction between ethylphenylketene and different N-sulfonylbenzaldimines, during which we varied various experimental parameters. We showed that steric hindrance of the catalyst is critical, poorly hindered NHCs favoring cis diastereoisomers, while trans-beta-lactams were essentially produced when more congested catalysts were used. The reaction solvent is also a critical parameter, N,N-dimethylformamide allowing to obtain the best diastereoisomeric ratio, 16:84, in favor of the trans isomer. Finally, the reaction temperature and the nature of the substituent on the N-sulfonylated imine are less important. The last part of this chapter concerned the coordination of NHC•ketene adducts to ruthenium. Our starting hypothesis was that these betaines could provide simultaneously an NHC ligand and an alkylidene precursor (a ketene) to the metal. By this way and from adequate metallic precursors, we envisioned to synthetize second-generation Grubbs type complexes, benchmark catalysts for olefin metathesis, in one step and without the need to handle diazo compounds. Although the first exploratory experiments did not lead to the expected results, they provided crucial information to help achieve these syntheses in future investigations. [less ▲]

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See detailContribution à la caractérisation des cellules du ganglion spiralé et des cellules de Boettcher de l’épithélium cochléaire durant le développement chez les rongeurs
Cloes, Marie ULg

Doctoral thesis (2015)

As per a recent WHO report (2015), 360 million people worldwide suffer from invalidating deafness. In hearing physiology a central role is played by the sensory cells of the organ of Corti. The sensory ... [more ▼]

As per a recent WHO report (2015), 360 million people worldwide suffer from invalidating deafness. In hearing physiology a central role is played by the sensory cells of the organ of Corti. The sensory cells are responsible for the transduction of the acoustic stimuli into nerve impulses. Located nearby the sensory cells, Boettcher’s cells (BC) are barely known. The first part of our study aims at examining their morphology and ultrastructure during the postnatal development of the rat cochlear epithelium. Our morphological studies indicate that BC begin their differentiation around the 8th postnatal day (P8) and become mature around P20, once they are fully covered by Hensen’s and Claudius’ cells. Moreover, with the help of the transmission electron microscope, we noted the presence of apical tight junctions as long as BC are in contact with endolymph between P8 and P16. Our ultrastructural and immunohistological studies also show gap junctions between BC and the adjacent cells before the end of the covering process of BC. We also noted intermediate junctions between BC during the whole length of their maturation process. Finally we noticed cytoplasmic secretory granules and an accumulated material in the intercellular spaces between P8 and P25. Our data suggest that BC fulfill several functions in the cochlear epithelium: endolymphatic K+ recycling via the stria vascularis and the biosynthesis of the basilar membrane’s extracellular matrix. As the first and exclusive relay for the transmission of the auditory information to the central nervous system, the spiral ganglion (SG) is another key element of hearing physiology. The SG is mainly made up of neurons and glial cells. In an attempt to clarify the embryonic origin of the cells of the SG, we studied a strain of double transgenic mice Wnt1-Cre;Rosa26YFP, which are characterized by the permanent labelling of the neural crest cells by the YFP. We observed a constant labelling in the SG and in the stria vascularis, further supporting that the SG glial cells and the intermediate cells of the stria vascularis originate from the neural crests. However we also detected an additional and changeable positivity amongst the cells of the cochlear epithelium and osseous labyrinth, disqualifying the strain as a suitable tool of investigation. [less ▲]

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See detailRepresenting a Minority Group in Multinational Federal Systems: Career Patterns in Catalonia, Scotland and Wallonia
Dodeigne, Jérémy ULg

Doctoral thesis (2015)

Dans nos démocraties représentatives, comprendre « qui » gouverne et plus précisément « comment » et « pourquoi » certains accèdent aux positions de pouvoir a toujours été un enjeu démocratique majeur ... [more ▼]

Dans nos démocraties représentatives, comprendre « qui » gouverne et plus précisément « comment » et « pourquoi » certains accèdent aux positions de pouvoir a toujours été un enjeu démocratique majeur. Avec les processus de régionalisation et de fédéralisation observés à travers le monde, cette question s’est complexifiée en raison de la multiplication des lieux de décision politique. Dans de nombreux pays, les représentants politiques évoluent désormais dans des systèmes multi-niveaux. L’une des conséquences directes de ces réformes institutionnelles est la transformation des carrières parlementaires, particulièrement dans les régions minoritaires des états plurinationaux comme la Belgique, l’Espagne et le Royaume-Uni. L’objectif de cette recherche doctorale est double. D’une part, elle cherche à définir l’orientation régionale et/ou nationale qui caractérise la carrière des élus depuis l’instauration des assemblées régionales. D’autre part, elle vise à identifier les facteurs qui expliquent l’émergence de ces différents types de carrières. À cette fin, la thèse développe une étude comparée de la Catalogne, de l’Écosse et de la Wallonie qui combine analyses quantitatives et qualitatives. Une des conclusions majeures de cette recherche est que le niveau de pouvoir régional est devenu une arène politique de plus en plus attractive – voire prédominante pour certains acteurs. Toutefois, contrairement à ce qui fut suggéré par des études antérieures, les parlements nationaux espagnol, britannique et belge continuent d’être des arènes politiques attractives pour les élus catalans, écossais et wallons. [less ▲]

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See detailCompétitivité, valorisation des ressources et objectifs de sécurité alimentaire pour la filière sucrière au Maroc
Redani, Latifa ULg

Doctoral thesis (2015)

The general objective of this work is to examine the coherence between food security policies and economic efficiency and valuation of resources policies for the sugar sub-sector in Morocco. A food ... [more ▼]

The general objective of this work is to examine the coherence between food security policies and economic efficiency and valuation of resources policies for the sugar sub-sector in Morocco. A food security policy implies state intervention and thus leads implicitly to market distortions, while a resource valuation policy would imply a free market. To address this issue, I will firstly adopt an approach that involves a sugar market analysis (measuring determinants of demand and changes in international prices against their impact on food security). Then, an economic analysis which attempts at assessing the competitiveness of the various segments of the sugar sub-sector will be undertaken. Finally, an analysis of the relative valuation of resources (capital, labor and irrigation water) by sugar crops compared to different irrigated crops will be led, in order to determine their private and social returns on. The analysis of demand during the period between 2000 and 2010 shows that the trend of domestic consumption witnessed major increases, which lead to the enhancement of food insecurity for sugar in the future. The analysis of volatility of world sugar prices from 1960 to 2010, through the decomposition method of time series, allows the isolation of an accidental effect, which reflects variability due neither to seasonal effects nor to trend. This accidental effect is mainly marked during three periods: 1973-1975, 1980-1981 and 2009-2010. In terms of food security, these fluctuations in world sugar prices have no impact on household access to sugar, yet they have a significant impact on state budget. Any variation in prices in the international market is absorbed by the compensation system since prices are regulated by this system. The food safety policy conducted during the sixties and seventies have mitigated the country's dependence on imports and thus reduce the impact of world sugar price fluctuations. However, this policy has often been criticized in terms of market efficiency and valuation of resources. The economic analysis of the sugar sub-sector in Morocco shows that the different segments of the value chain don’t enjoy the same level of protection. If the production segment of sugar beet doesn’t receive any protection, the processing segment of raw sugar will remain protected. However, the level of this protection has generally declined during the post structural adjustment period. In terms of competitiveness, while the sugar beet crop becomes competitive, the effective competitiveness of the industrial segment, and given the significant distortions in the world market, is difficult to assess. The analysis of the valuation of resources (capital, labor and water) shows that sugar crops, especially sugar beets, value relatively better capital resources and labor than most horticultural crops. They occupy an important position in terms of employment and value added created per hectare. However, the valuation of irrigation water remains low for sugar beet (excluding the region of Doukkala). But the technology trend shows substantial opportunities for improvement. Food security policy for sugar has been efficient since it helped establish a competitive national production which is generally able to value resources better. The distortions introduced by state intervention gave the time to farmers to improve their technical skills and to become competitive in the framework of international market, marked as it was by significant distortions. Finally, a food security policy is in no way inconsistent with a policy of valuation of resources on the condition that when the sub-sector becomes competitive, a way to market mechanisms must be given. [less ▲]

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See detailEtude épidémiologique et moléculaire de la dyskinésie ciliaire chez le chien
Merveille, Anne-Christine ULg

Doctoral thesis (2015)

Les dyskinésies ciliaires primaires (DCP) sont des maladies génétiques rares regroupant des pathologies respiratoires liées à une anomalie constitutionnelle des cils dits “mobiles” (Leigh, 2006). Ces cils ... [more ▼]

Les dyskinésies ciliaires primaires (DCP) sont des maladies génétiques rares regroupant des pathologies respiratoires liées à une anomalie constitutionnelle des cils dits “mobiles” (Leigh, 2006). Ces cils jouent un rôle important dans l’organisme, notamment au niveau du tractus respiratoire, où ils entrent dans la composition de l’escalator mucociliaire. Ils jouent également un rôle au niveau du système reproducteur et durant l’embryogénèse. Chez l’homme, la prévalence des DCP est estimée à 1 :10.000 (Afzelius et Stenram, 2006). Chez le chien, il existe une trentaine de cas décrits dans la littérature dans 20 races différentes. Les deux espèces partagent des manifestations cliniques similaires, directement liées à la dysfonction de la mobilité ciliaire. La plupart des individus touchés présentent des signes dès leur plus jeune âge. Parmi ces signes, on retrouve une atteinte des voies respiratoires comprenant des infections récidivantes des voies hautes (rhino-sinusites) et basses (bronchites et bronchopneumonies qui mènent à de la bronchiectasie), mais aussi de l’infertilité et, dans la moitié des cas environ, des défauts de latéralité que l’on appelle situs inversus (Leigh, 2006). La structure des cils mobiles est hautement conservée entre les différentes espèces et se caractérise par un agencement de neuf paires de microtubules périphériques organisées autour d’une paire centrale de microtubules. A cette structure, se rajoutent des complexes protéiques qui permettent de stabiliser les différents composants comme les crêtes radiales ou le complexe régulateur des dynéines, mais aussi des protéines motrices qui permettent au cil de se mouvoir comme les bras de dynéine. Cet agencement est perturbé dans la grande majorité des DCP qui présentent différents types de défauts ultrastructuraux en fonction des différents gènes impliqués (Papon et al., 2010) (Jorissen et al., 2000b). Chez l’homme, comme chez le chien, le défaut ultrastructurel le plus fréquent est une atteinte des bras de dynéine externes. La plupart des DCP se transmettent selon un mode autosomique récessif et plusieurs gènes causals ont été identifiés (Zariwala et al., 2011). Toutefois, les bases moléculaires d’un certain nombre de cas chez l’homme restent à ce jour indéterminées et chez le chien aucun gène responsable n’avait été identifié avant cette présente étude. Le chien représente un modèle spontané de DCP qui pourrait être utile dans la découverte de nouveaux gènes impliqués dans cette pathologie. Les différents objectifs de ce travail étaient d’une part, d’étudier le phénotype clinique d’une DCP ségrégant au sein d’une race de chien, le bobtail, et d’autre part, d’identifier le mode de transmission génétique ainsi que les bases moléculaires de cette DCP. Nous avons également voulu étudier la fréquence de la mutation identifiée dans cette race. Une fois le gène identifié chez le bobtail, nous avons voulu déterminer si celui-ci pouvait être responsable de cas de DCP humaines présentant un phénotype ultrastructurel similaire à celui des bobtails atteints. Ensuite, nous avons voulu évaluer les conséquences qu’une dysfonction de ce gène pouvait entraîner, afin de gagner en compréhension sur le rôle de la protéine impliquée et pour confirmer que les mutations identifiées étaient bien à l’origine du phénotype clinique observé. Enfin, nous avons voulu déterminer si ce gène pouvait être impliqué dans d’autres ciliopathies. Nous avons tout d’abord obtenu des données cliniques sur une dizaine de chiens atteints. Tous appartenaient au même pedigree et présentaient un phénotype clinique caractéristique apparu très tôt dans la vie de l’animal. Ce phénotype se caractérisait par un jetage nasal bilatéral, une toux productive, une leucocytose neutrophilique et des infections respiratoires récurrentes dont les séquelles étaient visibles sur les radiographies thoraciques avec des lésions de bronchopneumonie touchant les lobes crâniaux et moyen droit ainsi que des lésions de bronchiectasie. L’analyse du sperme d’un de ses chiens mettait en évidence une réduction de la mobilité des spermatozoïdes et un pourcentage important de formes anormales en microscopie optique. Un situs inversus était également présent dans environ un tiers des cas. Les anomalies ciliaires observées en microscopie électronique chez ces chiens révélaient un phénotype ultrastructurel peu commun, associant une atteinte des bras de dynéine internes et des anomalies de la paire centrale de microtubules. L’analyse du pédigree de ces chiens était en faveur d’un mode de transmission autosomique récessif. L’étude d’association génome entier réalisée chez 5 atteints et 15 contrôles a permis d’identifier une région contenant 151 gènes candidats. Une sélection des gènes décrits comme impliqués dans la structure et/ou la fonction des cils (Gherman et al., 2006; Inglis et al., 2006) a permis une réduction drastique des gènes candidats. Le séquençage de ceux-ci a permis d’identifier un codon stop prématuré au sein de CCDC39, un gène codant pour une protéine enrichie en domaine « coiled-coils ». Tous les chiens atteints possédaient cette mutation à l’état homozygote tandis que leurs parents étaient tous hétérozygotes, confirmant ainsi le mode de transmission autosomique récessif. Après avoir mis au point un test génétique rapide basé sur la technologie Taqman, plus de 500 bobtails ont été génotypés afin d’estimer la fréquence de la mutation au sein de cette race. L’allèle muté se retrouvait plus fréquemment dans la population européenne avec une fréquence d’hétérozygotes autour de 19%. Les hétérozygotes étaient plus rares chez les chiens provenant d’Amérique du nord avec une fréquence d’hétérozygotes de 7%. Plusieurs éléments étaient en faveur du fait que cette mutation était bien la mutation causale. Premièrement, le séquençage d’une population de 80 chiens issus de 9 races différentes, n’a pas permis d’identifier une seule fois cette mutation. De plus, en étudiant l’expression de CCDC39 au sein de l’épithélium respiratoire de chiens porteurs, nous avons mis en évidence un phénomène de dégradation de l’ARNm non-sens. Une nette diminution de l’expression de CCDC39 était visible chez les atteints par rapport aux sains et la protéine était absente des cellules ciliées respiratoires des atteints, contrairement aux chiens contrôles. Nous avons également pu démontrer que CCDC39 était principalement exprimé dans les tissus ciliés chez la souris et chez l’homme. Enfin, pour confirmer définitivement que CCDC39 joue un rôle important dans la mobilité ciliaire, nous avons supprimé son expression à l’aide de morpholinos dans des embryons de zebrafish. L’injection provoquait l’apparition de défauts de latéralité, dose-dépendants. Ce phénotype était spécifique car il disparaissait lorsque les embryons étaient co-injectés avec de l’ARNm sauvage. Vu son implication dans une DCP canine, il était légitime de suspecter que CCDC39 pouvait être à l’origine de cas humains. Nous avons sélectionné une cinquantaine de patients présentant un phénotype ultrastruturel identique à ceux des bobtails atteints. Le séquençage de ces patients a permis d’identifier quinze mutations différentes. Chez la plupart des atteints, ces mutations étaient, soit à l’état homozygote, soit à l’état d’hétérozygote composite. Par contre, nous n’avons pas mis en évidence de mutation au sein de CCDC39 pour une vingtaine de patients atteints de DCP avec un phénotype ultrastructurel différent ou chez plus de 200 patients ne présentant que des défauts de latéralité. Afin de mieux comprendre la fonction de CCDC39 et l’impact de sa dysfonction sur la structure cilaire, nous avons analysé son expression au niveau protéique, en examinant des cellules épithéliales nasales prélevées par frottis brosse. Comme chez le chien, la protéine était absente des cellules épithéliales respiratoires des patients atteints, alors qu’elle était présente chez les contrôles. En utilisant des techniques d’immunofluorescence à haute résolution, nous avons pu démontrer que CCDC39 se localisait principalement au niveau de l’axonème ciliaire chez l’individu sain mais pas chez l’individu atteint. Afin de caractériser l’impact d’une déficience de CCDC39, nous avons étudié les autres composants de l’axonème ciliaire en utilisant des anticorps dirigés spécifiquement sur des sous-unités de l’axonème ciliaire. Nous avons ainsi pu démontrer que l’absence de CCDC39 est responsable d’une absence de certains constituants axonémaux comme les bras de dynéine internes ou le complexe régulateur des dynéines. Enfin, l’analyse du battement ciliaire de certains sujets atteints a permis de mettre en évidence un pattern dyskinétique, caractérisé par une amplitude réduite et des axonèmes rigides. Cette étude a permis d’identifier un nouveau gène impliqué dans les DCP tant dans la race bobtail que chez l’homme. Nous avons pu mettre en évidence que ce gène code pour une protéine axonémale dont l’absence est responsable d’une atteinte des bras de dynéine internes et d’une désorganisation axonémale, ce qui a pour conséquence un battement ciliaire dyskinétique. Le phénotype clinique présenté par les chiens atteints est remarquablement similaire à celui de l’homme, avec une atteinte sévère des voies respiratoires, mais également des anomalies spermatiques chez le mâle et l’existence de défaut de latéralité chez certains atteints. Comme dans la grande majorité des DCP, les individus ne présentent la maladie que s’ils recoivent deux copies défectueuses de CCDC39, puisque nous avons pu montré que tous les chiens atteints étaient homozygotes pour la mutation et que la plupart des patients humains atteints possédaient soit une mutation à l’état homozygote, soit deux mutations différentes. Toutes les mutations identifiées au sein de ce gène sont associées à une perte de fonction et sont vraisemblablement responsables d’une absence de production de la protéine, secondaire à un phénomène de dégradation de l’ARNm, comme nous avons pu le mettre en évidence chez le bobtail. Par la suite, d’autres études ont confirmé cette hypothèse en identifiant de nouvelles mutations au sein de CCDC39, pratiquement toutes liées à une perte de fonction (Blanchon et al., 2012) (Zariwala et al., 2013) (Antony et al., 2013). Les mutations identifiées étaient systématiquement associées à un phénotype ultrastructurel bien particulier représentant environ 12% des cas de DCP (Jorissen et al., 2000b) (Chilvers et al., 2003a) (Papon et al., 2010) (Shoemark et al., 2012). Simultaménent à la découverte de CCDC39, un autre gène, CCDC40, a été identifié comme étant responsable d’un phénotype ultrastrucurel identique. Ces deux gènes sont étroitement liés, puisque l’absence de CCDC40 affecte la localisation axonémale de CCDC39 au sein de la cellule ciliée (Becker-Heck et al., 2010). Ces deux gènes expliquent à eux seuls une grande proportion des patients présentant ce phénotype particulier (Blanchon et al., 2012) (Antony et al., 2013). Nous avons pu démontrer, par différentes méthodes, que ce gène jouait un rôle important dans la structure et la fonction des cils mobiles en observant que son expression était principalement localisée dans les organes présentant des cils mobiles et que la protéine était absente chez des individus porteurs de mutation. De plus, en inactivant l’expression de ce gène dans des embryons de zebrafish, nous avons observé l’apparition de défaut de latéralité ce qui suggère une atteinte des cils mobiles de la vésicule de Kupffer, responsable de l’asymétrie droite gauche. L’identification de ce gène est particulièrement intéressante car CCDC39 a été la première protéine enrichie en domaine « coiled-coils » a être impliquée dans une DCP et a permis de souligner l’importance de ces motifs pour la fonction du cil mobile. Depuis lors, plusieurs autres gènes possédant ces structures particulières ont été associés avec d’autres cas de DCP humaines (Becker-Heck et al., 2010) (Hjeij et al., 2014) (Horani et al., 2013a) (Knowles et al., 2013a) (Panizzi et al., 2012) (Wirschell et al., 2013). Le rôle exact de ces protéines riches en des domaines « coiled-coils » reste à préciser, mais elles semblent jouer un rôle dans la structure du complexe régulateur des dynéines et dans l’ancrage des bras de dynéine aux microtubules adjacents. Cette étude a permis d’identifier le premier gène responsable de DCP dans l’espèce canine. Le génotypage de plus 500 bobtails a permis d’établir que la mutation semble plus fréquente en Europe, ce qui pourrait être lié à l’usage intensif de certains grands champions dans les années 80. La disponibilité de ce test permettra aux éleveurs de dépister les porteurs asymptomatiques et évitera l’apparition de nouveaux atteints. Enfin, cette étude permet de mettre en lumière l’intérêt du chien en tant qu’organisme modèle pour identifier les origines génétiques de certaines pathologies humaines. En effet, le chien représente un modèle unique à bien des égards (Lequarré et al., 2011). Le chien bénéficie de soins médicaux de plus en plus poussés et chaque race de chien représente un isolat génétique, ce qui a pour conséquence une concentration de certains allèles morbides responsables de pathologies similaires à celles de l’homme. On peut ajouter que le chien possède un répertoire génétique très proche de celui de l’homme et que la strucure de son génome est particulièrement intéressante pour disséquer génétiquement des caractères mendéliens, mais aussi des caractères complexes (Lindblad-Toh et al., 2005). Enfin, ou peut imaginer que les bobtails atteints de DCP pourraient représenter une opportunité unique pour tester de nouvelles thérapies et éventuellement pour mettre au point une thérapie ciblée contre le défaut génétique responsable. [less ▲]

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See detailA geometric local frame approach for flexible multibody systems
Sonneville, Valentin ULg

Doctoral thesis (2015)

The notion of frame is ubiquitous in the kinematic description of flexible multibody models. In this work, a differential-geometric framework is selected to describe frame operations in a rigorous and ... [more ▼]

The notion of frame is ubiquitous in the kinematic description of flexible multibody models. In this work, a differential-geometric framework is selected to describe frame operations in a rigorous and systematic way. A frame transformation is thus seen as an element of the special Euclidean group $SE(3)$, which is represented by a four by four transformation matrix, and frame operations, such as spatial interpolation or time integration, rely on non-linear but analytical expressions in which translation and rotation contributions are inherently coupled. Based on this formalism, this thesis develops geometrically exact formulations of many classical components used in flexible multibody system modelling, which includes the formulation of a rigid body, several kinematic joints, a flexible beam, a flexible shell and a superelement. As opposed to most popular techniques in the literature, a local frame representation of the equations of motion is adopted in this work. This means that the unknown kinematic variables such as the motion increments, the velocities and the accelerations, as well as the generalized forces are all expressed in a local frame attached to the body. After spatial semi-discretization, the equations of motion of a multibody system take the form of differential-algebraic equations on a Lie group which can be conveniently solved in a global parametrization-free approach using a Lie group integration scheme. This thesis presents numerous arguments to recommend this framework for the development of efficient codes for the numerical simulation of flexible multibody systems. On the one hand, the proposed framework leads to novel and interesting theoretical aspects. For instance, it features a naturally singularity-free description of large rotations and it leads to inherently shear-locking free beam and shell finite elements. On the other hand, the formulation leads to unprecedented computational properties. The geometric non-linearities are naturally filtered out of the equilibrium equations such that non-linearities are significantly reduced, as compared to classical formulations. In particular, the iteration matrix, which is used in implicit integration schemes, is insensitive to overall large amplitude motions and is only affected by local relative transformations, such as deformations in flexible elements and relative motions in kinematic joints. This property can be exploited to strongly reduce computational costs, as compared to classical formulations. [less ▲]

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See detailExperimental study and modeling of the quasi-static mechanical behavior of Ti6Al4V at room temperature
Gilles, Gaëtan ULg

Doctoral thesis (2015)

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts ... [more ▼]

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts. The first one presents a literature review of the basic properties of titanium and its alloys (crystal structure, classification, deformation mechanisms), then it focuses on the specific mechanical features of Ti6Al4V. It also proposes a state of art in the field of the phenomenological constitutive laws used to model the mechanical behaviors of metals. The second part deals with the experimental campaign conducted on a 0.6 mm thick Ti6Al4V sheet. The devices and the tests are first described before giving the test results. The campaign includes experiments with monotonic and complex strain paths (tension, compression, simple shear, plane strain, Bauschinger tests, deep-drawing processes, layer compression tests). The experimental results show that the material displays anisotropy in yield stress, r-ratios and hardening, as well as a strength differential effect between tension and compression. The third part describes the implementation of the yield criteria CPB06exn in the non-linear finite element code LAGAMINE developed in MSM team. These criteria are selected to model the yield locus of Ti6Al4V since they are able to take into account both the anisotropy and the tension-compression asymmetry exhibited by the alloy. Several parameter identifications are performed using the classical simulated annealing algorithm. They determine that CPB06ex2 is required to represent the yield surface. The criterion is next associated to different hardening formulations: (1) Voce isotropic law; (2) mixed Voce isotropic – Armstrong-Frederick kinematic law; (3) model taking into account the evolution of the yield locus shape with the deformation. The identification of the hardening parameters is achieved from the monotonic and Bauschinger tests either by inverse method, or by the simulated annealing method. The last part of the thesis proposed a validation of the different modelings in the case of the layer compression tests and the deep-drawing processes. [less ▲]

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See detailEvaluation des systèmes de management de la sécurité et de la qualité de l’aquaculture du tilapia du Nil "Oreochromis niloticus" dans l’Ouest algérien.
Dergal, Nadir Boudjlal ULg

Doctoral thesis (2015)

Cette thèse a été entreprise afin d’élaborer et de développer le premier modèle HACCP spécifique pour la gestion de la qualité ante et post mortem du tilapia (Oreochromis niloticus) produit au niveau de ... [more ▼]

Cette thèse a été entreprise afin d’élaborer et de développer le premier modèle HACCP spécifique pour la gestion de la qualité ante et post mortem du tilapia (Oreochromis niloticus) produit au niveau de la ferme continentale "Fat-Steppes" (Ouest algérien). Pour ce faire, différents points critiques (PCC) ont été déterminés et maitrisés tout au long de la phase d’élevage et de commercialisation. Durant la phase d’élevage, les résidus d’antibiotiques, les résidus de la 17α-méthyle testostérone et la qualité microbiologique et physicochimique de l’eau et de l’aliment d’élevage ont été évalués. Une stratégie analytique pertinente a été développée basée sur une première technique microbiologique de screening qui a été améliorée et partiellement validée pour l’identification des tétracyclines et des fluoroquinolones. Suivie d’une seconde technique LC-UV-MS qui a été spécialement optimisée pour l’identification et la quantification de l’acide oxolinique. Une nouvelle méthode d’extraction, compatible avec un test immuno-enzymatique ELISA (enzyme-linked immunosorbent assay), a été optimisée pour la détection des résidus de 17α-méthyle testostérone (MT) dans la chair du poisson, dans l’eau et l’aliment d’élevage. Le profil nutritionnel du tilapia produit à Fat Steppes a été caractérisé en déterminant sa composition en macronutriments, son profil en acides gras et en acide aminés. Par la suite, l’évolution temporelle de la qualité hygiénique, du tilapia conservé à 4°C et 30°C, a été évaluée par une approche sensorielle, microbiologique (Flore Mésophile Aérobie Totale et Entérobactéries) et biochimique. L’analyse des diènes conjuguées, des hydroperoxydes et des TBARS "Thiobarbituric acid reactive substances" a servi pour évaluer l’oxydation lipidique. L’analyse d’azote basique volatil totat "ABVT", la triméthylamine "TMA" et les amines biogènes a servi pour évaluer la protéolyse bactérienne et enzymatique. Les résultats obtenus ont démontrés des performances satisfaisantes des deux techniques d’analyse des résidus d’antibiotiques. La capacité de détection (CCß) du test de screening est de 0,75 fois la limite maximale de résidus (LMR) de l’acide oxolinique (OXO) et la limite de la quantification chromatographique LC/UV est de LMR/20. Le délai d’attente de l’OXO est estimé à 8 jours après un traitement de six jours successifs avec une dose de 12 mg/ kg de poids vif. La nouvelle méthode d’extraction des résidus d’MT est acceptable en termes de rendement d’extraction (55 % pour la chair et 85 % pour l'eau) et de linéarité (R2 = 0,998). Le délai d’attente des résidus de la MT est estimé à deux mois après un traitement avec une dose ≤ 65 mg MT/kg d’aliment, pendant 28 jours, à partir du 10ème jour post-éclosion. Des seuils microbiologiques de 103 ufc/100 ml de coliformes fécaux et de 3 x 106 ufc/g de flore mésophile aérobie totale (FMAT) sont retenus comme critères de bonne qualité microbiologique de l’eau et de l’aliment d’élevage respectivement. Le tilapia algérien est considéré comme un poisson maigre (± 0,33 % de lipide) et riche en protéines (± 17,3 %). Son profil en acides aminés essentiels et en acides gras polyinsaturés est relativement intéressant. Les paramètres de performance de la nouvelle méthode HPTLC "High Performance Thin Layer Chromatography", développée pour le screening et la quantification de six amines biogènes d’intérêt, sont satisfaisants en termes de linéarité (R2 > 0,98), de justesse (> 84 %), de fidélité. La limite de détection (LOD) de la méthode HPTLC est de l’ordre de 5 µg.g-1 de chair de poisson. Les résultats de l’analyse organoleptique, microbiologique et biochimique sont fortement et positivement corrélés et révèlent que la date d’utilisation optimale du tilapia est limitée à 12 heures et à 5 jours de conservation à 30°C et à 4°C respectivement. Après ces délais, le poisson est rejeté par l’appréciation organoleptique et tous les seuils critiques établis dans ce travail sont dépassés. Des valeurs de l’ordre de : 6 log cfu g-1 pour les FMAT et les entérobactéries, 0,85 mg MDA kg-1 de poids humide, 35 mg ABVT-N 100 g-1 de chair, 8 mg TMA-N 100 g-1 de chair, 100 µg.g-1 de putrescine et de cadavérine sont retenus comme critères microbiologiques et biochimiques respectivement. [less ▲]

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See detailLa jurisprudence de la Cour constitutionnelle en procédure pénale : le Code d'instruction criminelle remodelé par le procès équitable ?
Michiels, Olivier ULg

Doctoral thesis (2015)

INTRODUCTION GÉNÉRALE Ma dissertation doctorale porte sur une question simple qui peut succinctement se résumer de la manière suivante : la Cour constitutionnelle développe-t-elle un modèle de procédure ... [more ▼]

INTRODUCTION GÉNÉRALE Ma dissertation doctorale porte sur une question simple qui peut succinctement se résumer de la manière suivante : la Cour constitutionnelle développe-t-elle un modèle de procédure pénale ? Cette question me paraissait intéressante dès lors que l’extension du socle de compétence de la Cour constitutionnelle au titre II de la Constitution a considérablement renforcé la « constitutionnalisation » du droit pénal sensu lato et que le catalogue constitutionnel belge des droits fondamentaux a subi un véritable bouleversement à la suite de l’évolution des droits et libertés garantis par les instruments internationaux, dont la Convention européenne des droits de l’homme. Afin de disposer des bases nécessaires pour appréhender ce sujet d’étude, il convenait, d’une part, de déterminer les possibilités d’action de la Cour constitutionnelle dès l’instant où sa saisine se réalise par voie de questions préjudicielles ou de recours en annulation et de cerner l’éventuelle ingéniosité juridique que la doctrine prête à la Cour pour étendre son analyse au delà de la vision manichéenne de la constitutionnalité. D’autre part, il était nécessaire de procéder à une recension des arrêts prononcés par la Cour constitutionnelle, dans le but toujours de vérifier si, et, le cas échéant, comment la Cour s’inscrit ou non dans une logique définie de la procédure pénale. J’ai, dès lors, après avoir rappelé le socle de compétence de la Cour constitutionnelle, la manière dont cette dernière est saisie et les techniques récurrentes auxquelles la Cour recourt dans la construction de ses arrêts, procédé à un inventaire des principaux arrêts prononcés par la Cour constitutionnelle en procédure pénale. Sciemment, j’ai pris comme point de départ de cette recension l’année 1998 qui a vu entrer en vigueur la loi du 12 mars 1998, dite Franchimont, dont le but était de donner un cadre légal et résolument actuel à l’information et à l’instruction. Une fois ce travail réalisé, j’ai entrepris de déterminer s’il était possible de dégager des prises de position répétées de la Cour qui s’imposeraient comme autant de « fondamentaux » qui jalonnent la procédure pénale. QUELS SONT LES FONDAMENTAUX DE LA COUR CONSTITUTIONNELLE EN PROCEDURE PENALE ? De la jurisprudence de la Cour constitutionnelle, il me paraît qu’il est possible de dégager 7 fondamentaux qui balisent la procédure pénale. 1. LA DISTINCTION ENTRE LES PARTIES AU PROCES PENAL ET LES PHASES PROCEDURALES 1. L’on sait que la Cour constitutionnelle estime qu’il existe une différence fondamentale entre le ministère public, d’une part, et l’inculpé et la partie civile, d’autre part. Pour la Cour, cette distinction repose sur un critère objectif : le premier accomplit, dans l’intérêt de la société, les missions de service public relatives à la recherche et à la poursuite des infractions ; les seconds défendent leur intérêt personnel . Cette différence justifie raisonnablement que, tout particulièrement au long de l'instruction, le ministère public jouisse de prérogatives dont la constitutionnalité ne peut être appréciée en procédant à une comparaison de sa situation avec celle de l'inculpé. 2. Lors de la phase du jugement, la différence tend à s’amenuiser. Il serait toutefois hasardeux de soutenir que le ministère public devient une partie comme les autres. En effet, par la Cour de cassation – dans un arrêt du 19 décembre 2012 discuté dont l’analyse m’éloignerait de mon sujet – retient que « la mission impartie au ministère public ne se réduit pas à celle d’un accusateur. Il intervient aussi au procès pour proposer au juge une solution de justice ». La Cour constitutionnelle insiste pareillement sur le rôle imparti au ministère public qui ne se cantonne pas à celui d’une simple partie au procès pénal au regard des missions qui sont les siennes. Cependant, si la distinction entre les différentes parties au procès répressif repose sur un critère objectif, la Cour constitutionnelle m’admettrait pas que cette seule différence puisse porter atteinte au principe de l’égalité des armes ce qui l’amènerait inévitablement à rétablir l’égalité. 2. LE DROIT D’ACCES AU JUGE 3. L’approche de la Cour constitutionnelle quant au droit d’accès à un tribunal est tout en nuance. Pour la Cour, ce droit peut ne pas être absolu et peut souffrir de limitations. Ainsi, la Cour insiste sur le fait que si le droit d’accès au juge peut être soumis à des conditions de recevabilité, celles-ci ne peuvent aboutir à restreindre le droit de manière telle qu’il s’en trouve atteint dans sa substance même. Une telle motivation n’est pas sans rappeler la jurisprudence de la Cour européenne des droits de l’homme sur le sujet. En effet, pour la Cour européenne des droits de l’homme, « ce droit d’accès au tribunal se trouve atteint lorsque sa réglementation cesse de servir les buts de la sécurité juridique et de la bonne administration de la justice et constitue une sorte de barrière qui empêche le justiciable de voir son litige tranché au fond par la juridiction compétente ». On aperçoit immédiatement que, la question du droit d’accès au juge est, sous certains aspects, intimement liée à celle du formalisme procédural. 3. LE FORMALISME PROCEDURAL 4. Par l’examen des règles de forme, la Cour renforce le contrôle qu’elle porte sur le droit d’accès au juge. En effet, la Cour en réalisant une distinction entre les règles de fond – entendues comme le droit garanti ou protégé – et de forme –qui déterminent les manières de procéder –elle confère un volet substantiel à certaines règles procédurales. Ce faisant, la Cour garantit l’effectivité du droit revendiqué qui est souvent dépendante de la protection procédurale qui l’encadre. 4. LA NON-INTERFERENCE DANS LES CHOIX D’OPPORTUNITE DU LEGISLATEUR 5. La Cour constitutionnelle ne se prononce pas sur le caractère approprié ou non du choix opéré par le législateur. Elle n’est pas le juge de « l’opportunité législative ».Son contrôle porte, en fait, sur l’adéquation d’une mesure au but recherché et l’existence d’un rapport raisonnable entre les moyens employés et l’objectif visé. Cependant, à nouveau, la Cour s’autorisera à sanctionner le choix du législateur s’il était porté atteinte, sans justification raisonnable, aux droits d’une catégorie de citoyens. 5. LE RESPECT DES DROITS DE LA DEFENSE 6. Au fil de sa jurisprudence, la Cour constitutionnelle se montre intensément attentive au respect des droits de la défense et au droit à un procès équitable qui, à vrai dire, sont l’essence même de la procédure pénale. La Cour veille, au stade du jugement, à assurer l’égalité des armes entre l’accusation et la défense à laquelle le droit à la contradiction est étroitement lié. Pour la Cour constitutionnelle, l’effectivité des droits de la défense passe encore par la protection de la relation de confiance qui doit se créer entre le justiciable et l’avocat qui le conseille et le défend. Le secret professionnel de l’avocat constitue « l’un des principes fondamentaux sur lesquels repose l’organisation de la justice dans une société démocratique ». 7. De manière globale, on notera que la notion de droits de la défense garantie par la Cour constitutionnelle est viscéralement marquée du sceau de la jurisprudence de la Cour européenne des droits de l’homme mais il lui revient d’intégrer ces données dans le système procédural belge en ayant égard aux choix réalisés par le législateur. 6. LA DIFFERENCIATION ENTRE LES PROCEDURES JUDICIAIRES 8. La Cour semble, a priori, rejeter une comparaison d’office entre les règles de la procédure civile et celles de la procédure pénale quand bien même la première constitue le droit commun. La Cour rappelle que vouloir établir un parallélisme entre les règles de la procédure civile et celles de la procédure pénale n’est pas nécessairement pertinent. En effet, l’application de règles procédurales différentes dans des circonstances différentes n’implique pas en soi l’émergence d’une discrimination. 7. LA PREVISIBILITE 9. Certains arrêts prononcés par la Cour constitutionnelle permettent de mettre en lumière l’importance que cette dernière accorde à la condition de prévisibilité. En droit pénal, sensu stricto, la Cour a pu rappeler qu’il découle de l’article 12, alinéa 2, de la Constitution que la loi pénale doit être formulée en des termes qui permettent à chacun de connaître, au moment où il adopte un comportement, si ce comportement est punissable ou non et la peine éventuellement encourue. Les principes de légalité et de prévisibilité ne se cantonnent toutefois pas au droit pénal, sensu stricto, mais sont applicables à l’ensemble de la procédure pénale en ce compris aux stades de l’information et de l’instruction. Ces principes entendent exclure tout risque d’intervention arbitraire de la part du pouvoir exécutif ou du pouvoir judiciaire dans l’établissement et l’application des peines. En somme, l’exigence de prévisibilité de la procédure pénale garantit à tout citoyen qu’il ne pourra faire l’objet d’une information, d’une instruction et de poursuites que selon une procédure établie par la loi et dont il peut prendre connaissance avant sa mise en oeuvre. CHAPITRE 3. VERS LA RECOMPOSITION DE LA PROCEDURE PENALE ? 10. Si, pour ma part, la Cour constitutionnelle dégage des « principes constants » qu’elle s’astreint à respecter, peut-on nécessairement en déduire que la Cour entend s’inscrire dans un modèle précis de procédure pénale ? Pour appréhender cette question, il convient naturellement d’apprécier si la Cour constitutionnelle, par les orientations qu’elle confère à ses arrêts, ouvre au juge judiciaire des perspectives qui lui permettront de se libérer d’une interprétation traditionnelle de la norme pour satisfaire aux exigences d’aujourd’hui envisagées sous l’angle du respect de la personne et de ses droits fondamentaux ? Il me paraît que la Cour y parvient par le recours au dialogue des jurisprudences. 1. LE DIALOGUE DES JURISPRUDENCES 11. Le dialogue des jurisprudences se caractérise par l’emprunt de motivations émanant de juridictions nationales ou de juridictions étrangères ou internationales qui deviennent décisoires dans les arrêts de la Cour constitutionnelle. 12. La Cour constitutionnelle s’est résolument et immédiatement positionnée en faveur du dialogue des jurisprudences. Nombre des arrêts que nous avons répertoriés se réfèrent expressément à la jurisprudence de la Cour européenne des droits de l’homme dont elle fait sien les enseignements. Au fil des années, les emprunts à la jurisprudence strasbourgeoise se sont accentués et non plus seulement en termes de référence mais encore en termes de contenu. La suprématie, selon la Cour constitutionnelle, de notre Charte fondamentale sur la Convention européenne des droits de l’homme n’enraie nullement ce dialogue. Par ces emprunts, la Cour constitutionnelle renforce, selon moi, ces « principes fondamentaux », et par là même leur autorité persuasive, en s’appuyant sur la notoriété et le rayonnement international de la Cour européenne des droits de l’homme. Un tel dialogue contribue à promouvoir le caractère universel des garanties fondamentales inhérentes au procès pénal et oblige à la confrontation des idées entre les juridictions ce qui doit permettre, me semble-t-il, de surmonter les tensions entre elle et la Cour de cassation. Il est vrai que ces deux hautes juridictions s’affrontent sur certains points, mais ces divergences ne doivent pas être exagérées car je persiste à penser que ces deux Cours doivent avoir l’intelligence stratégique de coordonner leur interprétation, dès lors que de telles divergences de jurisprudence en procédure pénale le sont toujours au détriment du justiciable alors que le but premier des règles de procédure est d’assurer la protection des droits fondamentaux de ce dernier. Ceci étant ce dialogue des jurisprudences ne va-t-il pas faire craindre l’émergence d’une « oligarchie » des juges et à plus forte raison que des juges pourraient s’émanciper par rapport à la loi en saisissant d’autres juges qui pourraient mettre le législateur « hors jeu »? 2. L’ « OLIGARCHIE » DES JUGES 13. Je crois qu’il ne faut pas amplifier le phénomène car la Cour constitutionnelle privilégie l’interprétation téléologique et rappelons-le elle n’entend pas, en règle, substituer son appréciation à celle du législateur si le choix est raisonnable. Par ailleurs, pour faire très bref, la Cour constitutionnelle devient le lieu de débats et d’échanges d’arguments où le travail légistique est réexaminé au regard des droits et libertés garantis par la Constitution couplés bien souvent à la Convention européenne des droits de l’homme. Si bien que les juges constitutionnels belges et, par ricochet le législateur, lorsqu’il obtempère aux injonctions qui lui sont faites par ces derniers, s’alignent sur l’appréciation de l’équité du procès telle qu’elle se dégage des positions adoptées par la Cour européenne des droits de l’homme. Mais le pouvoir du dernier mot appartient au législateur. 14. A l’inverse ne pourrait-on penser que de facto en raison de la composition de la Cour qui contient en son sein d’anciens mandataires politiques, le pouvoir législatif ne garde-t-il pas une certaine mainmise sur le contrôle de la constitutionnalité des lois ? 3. LA COMPOSITION DE LA COUR CONSTITUTIONNELLE Répondre à cette question relève du divinatoire et poserait en postulat que le juge, ancien parlementaire, serait un défenseur de la norme critiquée ce qui ne peut scientifiquement être démontré. Il ne paraît, dès lors, qu’il s’agit là d’une crainte infondée. Un dernier point doit, en revanche, être souligné : le pragmatisme et le conséquentialisme de la Cour. CHAPITRE 4. PRAGMATISME ET CONSEQUENTIALISME DE LA COUR CONSTITUTIONNELLE 15. Une autre grande tendance se dégage des arrêts analysés, le pragmatisme dont fait preuve la Cour dans le but d’assurer une véritable praticabilité à la procédure. 16. En parallèle au pragmatisme, le moyen conséquentialiste ne peut être négligé. Bien évidemment, tous les arrêts prononcés par la Cour ont nécessairement une conséquence dans leur sphère d’application. En l’espèce, par conséquentialisme il faut entendre plus précisément les positions adoptées par la Cour qui sont teintées de réalisme « politique » qui répond à des impératifs budgétaires ou de sécurité nationale ou encore à une volonté populaire. Ces données réelles et par toujours facile à identifier peuvent évidemment constituer autant des contraintes susceptibles de limiter la liberté d’appréciation par la Cour d’un modèle de procédure pénale. CONCLUSIONS 17. Alors, en définitive, est-il possible de répondre à ma question initiale : la Cour constitutionnelle développe-t-elle un modèle de procédure pénale ? A l’examen, il paraît illusoire, voire naïf, de vouloir répondre à cette interrogation de manière catégorique. Une telle réponse manquerait de nuances et prêterait nécessairement le flanc à la critique. Il faut donc procéder par touches successives et observer que le critère phare du raisonnement de la Cour constitutionnelle devient celui de l’équité du procès. La Cour n’en garde pas moins à l’esprit qu’elle doit maintenir la cohérence du système juridique dans lequel elle se meut et que ses interventions sont, somme toute, conditionnées par les recours et les questions qui lui sont adressés et qui dépendront, pour ces dernières, de l’attitude adoptée par le juge a quo. Par ailleurs, la Cour ne manque pas de souligner que la procédure pénale reste encadrée par le principe de légalité sans que la marge de manœuvre du pouvoir judiciaire – et de la Cour constitutionnelle elle-même – ne puisse jamais aller au-delà d’une interprétation raisonnablement prévisible des règles de procédure fixées par le seul législateur. Enfin, l’argument conséquentialiste, qu’il n’est pas toujours aisé de distinguer dans le raisonnement de la Cour, peut complètement chambouler la grille de lecture que l’analyste tenterait de dresser. En conclusion, s’il ne fallait retenir qu’une chose de ma thèse c’est que la si la Cour constitutionnelle ne développe pas un modèle de procédure pénale, il n’en est pas moins vrai, qu’à l’aulne du procès équitable, dont il ne paraît guère possible de cerner le périmètre d’action, elle refaçonne résolument cette procédure. [less ▲]

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See detailSatellite Orbits in the Atmosphere: Uncertainty Quantification, Propagation and Optimal Control
Dell'Elce, Lamberto ULg

Doctoral thesis (2015)

From the massive international space station to nanosatellites, all space missions share a common principle: orbiting an object requires energy. The greater the satellite's mass, the higher the launch ... [more ▼]

From the massive international space station to nanosatellites, all space missions share a common principle: orbiting an object requires energy. The greater the satellite's mass, the higher the launch cost. In astrodynamics, this translates into the motto ``use whatever you can''. This concept encompasses a broad spectrum of missions, e.g., the Earth's oblateness is exploited for sun-synchronous orbits and the kinetic energy of a planet is used to accomplish fly-by maneuvers. Nowadays, the same paradigm is coming on stream in the context of distributed space systems, where complex missions are envisaged by splitting the workload of a single satellite into multiple agents. Orbital perturbations -- often regarded as disturbances -- can be turned into an opportunity to control the relative motion of the agents in order to reduce or even remove the need for on-board propellant. This thesis is an attempt to combine uncertainty quantification, analytical propagation, and optimal control of satellite trajectories in the atmosphere for effectively and robustly exploiting the aerodynamic force. Specifically, by means of a probabilistic estimation and prediction of the aerodynamic force and an efficient and consistent propagation of low-Earth orbits, a robust reference trajectory for the realization of relative maneuvers between two satellites in a realistic environment can be generated. [less ▲]

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See detailGraded-commutative nonassociative algebras: higher octonions and Krichever-Novikov superalgebras; their structures, combinatorics and non-trivial cocycles.
Kreusch, Marie ULg

Doctoral thesis (2015)

This dissertation consists of two parts. The first one is the study of a series of real (resp. complex) noncommutative and nonassociative algebras $\bbO_{p,q}$ (resp. $\bbO_{n}$) generalizing the algebra ... [more ▼]

This dissertation consists of two parts. The first one is the study of a series of real (resp. complex) noncommutative and nonassociative algebras $\bbO_{p,q}$ (resp. $\bbO_{n}$) generalizing the algebra of octonion numbers $\bbO$. This generalization is similar to the one of the algebra of quaternion numbers in Clifford algebras. Introduced by Morier-Genoud and Ovsienko, these algebras have a natural $\bbZ_2^n$-grading ($p+q =n$), and they are characterized by a cubic form over the field $\bbZ_2.$ We establish all the possible isomorphisms between the algebras $\bbO_{p,q}$ preserving the structure of $\bbZ_2^n$-graded algebra. The classification table of $\bbO_{p,q}$ is quite similar to that of the real Clifford algebras $\cC l_{p,q}$, the main difference is that the algebras $\bbO_{n,0}$ and $\bbO_{0,n}$ are exceptional. We also provide a periodicity for the algebras $\bbO_n$ and $\bbO_{p,q}$ analogous to the periodicity for the Clifford algebras $\cC l_{n}$ and $\cC l_{p,q}$. In the second part we consider superalgebras of Krichever-Novikov (K-N) type. Krichever and Novikov introduced a family of Lie algebras with two marked points generalizing the Witt algebra and its central extension called the Virasoro algebra. The K-N Lie (super)algebras for more than two marked points were studied by Schlichenmaier. In particular, he extended the explicit formula of $2$-cocycles due to Krichever and Novikov to multiple-point situation. We give an explicit construction of central extensions of Lie superalgebras of K-N type and we establish a $1$-cocycle with values in its dual space. In the case of Jordan superalgebras related to superalgebras of K-N type, we calculate a 1-cocycle with coefficients in the dual space. [less ▲]

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See detailPhotochemical generation of reactive oxygen species using plasmonic nanoparticles
Lismont, Marjorie ULg

Doctoral thesis (2015)

During his lecture entitled “ There is plenty of room at the bottom ”, Richard Feyn- man foresaw the possibility of manipulating material at the scale of individual atoms and molecules. Although Feynman’s ... [more ▼]

During his lecture entitled “ There is plenty of room at the bottom ”, Richard Feyn- man foresaw the possibility of manipulating material at the scale of individual atoms and molecules. Although Feynman’s conceptual idea of a nanoworld was evoked in 1959, the nanoscience and nanotechnology revolution began 30 years later with the ability to see at the atomic scale with the invention of electronic microscopy and related tools. The size range that has attracted so much attention over these last 30 years is typically from 100 nanometers down to the atomic level. Subsequently, nanomaterials were defined as materials, which have structured components with at least one dimension in this size range. For instance, material with three nanometric dimensions defines a nanoparticle. Among the variety of core materials available to synthesize nanoparticles, noble metal nanoparticles, i.e. gold and silver, have fascinated people for centuries owing to their bright and intense colors, used in particular as decorative pigments in cathedral stained glasses and artworks. The red and yellow colors displayed by gold and silver nanoparti- cles arise from their interaction with light, which one induces collective oscillations of free electrons at the nanoparticle surface in resonance with the light field. This phenomenon is commonly known as the localized surface plasmon resonance. Their remarkable optical properties and the intense electric field generated by plasmonics nanoparticles have brought these nanomaterials in the forefront of nanotechnology research, ranging from photonics to medicine. Shining light on plasmonic nanoparticles to push back limitations of light-activated therapy and so taking part to the societal challenge of cancer treatment improvement defines the global framework of the thesis. Falling within the nanomedicine topic, this one more precisely deals with the development of efficient plasmonic nano-drugs using light to cure diseases. Clearly, nanoplasmonics, which explores how electromagnetic field can be confined over dimension on the order or smaller than the wavelength of light, has come a long way since the stained glass of Roman times. [less ▲]

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See detailNonparametric and bootstrap techniques applied to financial risk modeling
Hambuckers, julien ULg

Doctoral thesis (2015)

For the purpose of quantifying financial risks, risk managers need to model the behavior of financial variables. However, the construction of such mathematical models is a difficult task that requires ... [more ▼]

For the purpose of quantifying financial risks, risk managers need to model the behavior of financial variables. However, the construction of such mathematical models is a difficult task that requires careful statistical approaches. Among the important choices that must be addressed,we can list the error distribution, the structure of the variance process, the relationship between parameters of interest and explanatory variables. In particular, one may avoid procedures that rely either on too rigid parametric assumptions or on inefficient estimation procedures. In this thesis, we develop statistical procedures that tackle some of these issues, in the context of three financial risk modelling applications. In the first application, we are interested in selecting the error distribution in a multiplicative heteroscedastic model without relying on a parametric volatility assumption. To avoid this uncertainty, we develop a set of model estimation and selection tests relying on nonparametric volatility estimators and focusing on the tails of the distribution. We illustrate this technique on UBS, BOVESPA and EUR/USD daily stock returns. In the second application, we are concerned by modeling the tail of the operational losses severity distribution, conditionally to several covariates. We develop a flexible conditional GPD model, where the shape parameter is an unspecified link function (nonparametric part) of a linear combination of covariates (single index part), avoiding the curse of dimensionality. We apply successfully this technique on two original databases, using macroeconomic and firm-specific variables as covariates. In the last application, we provide an efficient way to estimate the predictive ability of trading algorithms. Instead of relying on subjective and noisy sample splitting techniques, we propose an adaptation of the .632 bootstrap technique to the time series context. We apply these techniques on stock prices to compare 12,000 trading rules parametrizations and show that none can beat a simple buy-and-hold strategy. [less ▲]

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See detailPolyphosphate-based amphiphilic copolymers: synthesis and application to drug nanocarriers
Vanslambrouck, Stéphanie ULg

Doctoral thesis (2015)

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications, especially for drug delivery systems. In contrast to aliphatic polyesters ... [more ▼]

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications, especially for drug delivery systems. In contrast to aliphatic polyesters, such as poly(?-caprolactone) and poly(lactide), the pentavalency of phosphorus atom allows the easy modification of the polyphosphate properties by simply adjusting the nature, the length and the functionality of the polyphosphate pendants groups. The goal of this thesis focused on the design of drug nanocarriers based on amphiphilic block copolymer micelles well-suited for the encapsulation of poorly soluble drugs. For that purpose, novel diblock copolymers composed of a water-soluble poly(ethylene oxide) block and a polyphosphate block bearing a variety of alkyl side-groups were synthesized. Firstly, n- butyl, i-butyl and n-heptyl cyclic phosphate monomers were synthesized and used for the organo-catalyzed ring-opening polymerization providing a range of PEO-b-polyphosphate amphiphilic copolymers varying by the architecture and length of the polyphosphate pendant group. Then, post-polymerization thiol-ene click reactions on preformed PEO-b- polybutenylphosphate copolymer was used to graft dodecyl or tocopherol side-chains on the polyphosphate block.The micellization of these amphiphilic block copolymers in aqueous medium was then investigated and a comparative study of the encapsulation and release of a poorly soluble model drug, i.e. ketoconazole, was carried out. Ultimately, the synthesis of a triblock copolymer was investigated to prepare shell- crosslinked core-shell-corona micelles to improve the nanoparticles stability. [less ▲]

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See detailThe System for Adressing Personal Problems-From medicalisation to Socialisation: Shifts in Belgian Psychiatric and Mental Health Institutions
Thunus, Sophie ULg

Doctoral thesis (2015)

My PhD thesis related the growth of a large social system devoted to the treatment of personal problems; i.e. problems successively labelled as madness, mental illness and mental health problems, from the ... [more ▼]

My PhD thesis related the growth of a large social system devoted to the treatment of personal problems; i.e. problems successively labelled as madness, mental illness and mental health problems, from the early fifties to the present days. That system involved heterogeneous networks of actors, including scientific experts, established professions, social movements, policy makers, services users and international organisations; instruments and knowledge ranging from psychoanalytical theories to biological knowledge and models of governance. It meant to explain how institutional change happened in that complex social system, by studying past and ongoing reforms, considered as interrelated steps towards complete paradigm shift, including shifting policy means, policy objectives and social organisation. By relying on in-depth analyses of five past reforms, it conceptualised the system as composed of interrelated ecologies, corresponding to different kinds of knowledge of personal problems, whose development was directed by protective and expansion strategies used by two coalitions of actors, holding different kinds of resources to influence the change process. The traditional coalition was embedded in the Belgian institutional system; it referred to medical knowledge of personal problems; and held many institutions delivering residential treatments. By contrast, the reformist coalition was connected to international professional and policy networks stimulating change in OECD-mental health systems; it referred to practical knowledge of social psychiatry and evidence produced by international organisations as the World Health Organisation; and it held non-profit associations delivering community treatments. Cross-regulations exerted through joint-participation of those coalitions in successive reforms caused rapid changes in the system’s structural configuration while hindering change in its social organisation. Thus, we suggested thinking of the issue of change in the system as consisting in setting conditions in which the reformist coalition might extensively use its resources in conducting a new reform starting in 2010. By relying on that assumption, I presented three case studies analysing the devising of that reform at the policy level and its implementing through local networks. Those case studies drew attention to the kinds of knowledge used by key actors and to the way in which they used it in joint-attempts to take the leadership of the reform. Three main findings resulted from those case studies. First, the designing of the policy guide framing the reform consisted in assembling different kinds of knowledge together, including policy learning achieved through past changes in the system and knowledge of alternative care models implemented in OECD-countries, in a way that encouraged sustained enactments of knowledge specific to the reformist coalition, while decreasing the relevance of resources specific to the traditional coalition. Second, local meetings caused by the implementing of the reform enabled adaptations of knowledge embodied by the participants, i.e. multiple actors representing different ecologies and members of one of the two coalitions, to enacted knowledge, i.e. knowledge collectively produced by thinking about concrete means to implement the reform locally. Third, enacted knowledge caused, in turn, adaptations of the care model inscribed in the policy guide to local particularities. Those adaptations did not prevent, however, the global philosophy of the new reform, inspired by social psychiatry, from pervading in local networks, among other by being inscribed in operational documents resulting from meetings. Thus, by following the policy guide through local networks where it was translated into concrete practices, I have been able to indicate new directions in the global process of change in the system, towards a complete paradigm shift, from medical to social psychiatry, and to highlight social and learning processes making it possible. [less ▲]

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See detailOn-line Dynamic Security Assessment in Power Systems.
Weckesser, Johannes ULg

Doctoral thesis (2015)

The thesis concerns the development of tools and methods for on-line dynamic security assessment (DSA). In a future power system with low-dependence or even independence of fossil fuels, generation will ... [more ▼]

The thesis concerns the development of tools and methods for on-line dynamic security assessment (DSA). In a future power system with low-dependence or even independence of fossil fuels, generation will be based to a large extent on non-controllable renewable energy sources (RES), such as wind and solar radiation. Moreover, ongoing research suggests that demand response will be introduced to maintain power balance between generation and consumption at all times. % as well as to account for forecasting inaccuracies related to power generation from RES. Due to these changes, the operating point of the power system will be less predictable. Consequently, today's stability and security assessment tools, which are generally dependent on extensive off-line studies, may no longer be feasible in their current development state. A core component of an efficient on-line dynamic security assessment is a fast and reliable contingency screening. As part of this thesis a contingency screening method is developed and its performance is assessed utilizing a set of test cases. The developed method reliably assesses first-swing transient angular stability of a power system in its current state with respect to a given set of contingencies. In order to ensure fast performance of the screening method, first a review of existing transient stability assessment (TSA) methods was carried out and their computational complexity was investigated. This allowed to identify the single machine equivalent (SIME) method as the potentially fastest assessment method and, hence, well suited for on-line DSA. Means for further performance improvement of the SIME method are investigated such as the reduction of the degree of system model detail used in time-domain simulation. This results in a recommendation for the required model detail for synchronous generator. A challenging task when using the SIME method is to early and reliably determine the critical machine cluster, which is the group of generators likely to lose synchronism. Therefore, a novel approach to identify the critical machine cluster is proposed in the thesis. This approach uses a new coupling coefficient, which is a measure of the coupling strength of pairs of generators, and a simple clustering algorithm to identify the critical group of generators. In order to determine a system to be transient secure, it is not sufficient to solely assess if all synchronous generators remain in synchronism, it is also required that the bus voltages remain within acceptable limits. A transient disturbance and the following angular divergence of a group of generators can cause critical voltage sags at certain buses in the system. In this thesis assessment of such voltage sags is proposed using two types of sensitivities, which are derived from the algebraic network equations. These sensitivities are derived after an in-depth study of the mechanism causing the voltage sags. The first sensitivity type is called load voltage sensitivity and allows identifying which bus voltages are affected by a change in rotor angle of a particular generator. % It is shown that the derived load voltage sensitivities for example allow to determine the contribution of each generator to an observed voltage sag, which is valuable information for identifying preventive controls. The second proposed type is called generator power sensitivity, which provides information on the effect of load variation on the generator's power injection. It is shown that the derived sensitivities can give valuable information to identify critical generator-load pairs as well as locations for applying preventive or remedial control measures. Furthermore, the development of a method for early prediction of critical voltage sags is described. The method's performance is compared to other prediction approaches. The results show that the proposed method succeeds in early, accurately and consistently predicting critically low voltage sags. An efficient on-line DSA not only identifies unstable or insecure operation, but also proposes preventive or remedial control actions to restore stability and security in the system. In this thesis a further development of a method for determining real-time remedial action against aperiodic small signal rotor angle instability is described. A real-time aperiodic small signal rotor angle stability assessment method is employed to monitor the respective stability boundary and to compute the respective stability margin of each generator in the system. In case that the stability margin of a particular generator falls below a pre-defined security threshold, the proposed method analytically determines power generation re-dispatch solutions, which restore stable and secure operation in the system. The effectiveness of the method is presented on two test cases in two different test systems. [less ▲]

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See detailDe quels marchés boursiers l’Afrique a-t-elle besoin pour son développement ? Au-delà des illusions, une étude précise de l’attractivité et de l’efficience des marchés boursiers africains
Teuwa Nkeuwo, Mathieu Hugues ULg

Doctoral thesis (2015)

Les marchés boursiers africains ont connu durant ces deux dernières décennies de profondes mutations et une évolution en terme numérique. Face à ces changements et aux impératifs de rentabilité, ces ... [more ▼]

Les marchés boursiers africains ont connu durant ces deux dernières décennies de profondes mutations et une évolution en terme numérique. Face à ces changements et aux impératifs de rentabilité, ces marchés sont entrés dans une logique de concurrence. Ce faisant, ils se doivent aujourd’hui d’offrir à leurs clients des services de qualité supérieure à des coûts compétitifs. Pendant ce temps, le continent africain connaît, depuis ces dernières années, une progression de sa croissance économique et fait l’objet d’attractivité et de convoitise de la part des investisseurs étrangers. L’objectif de cette thèse est de déterminer le type de marché boursier dont l’Afrique a besoin pour stimuler sa croissance économique, dans un environnement concurrentiel marqué par une double évo- lution sous les angles de la croissance économique et de la dynamique des marchés boursiers. Pour atteindre cet objectif, ce travail analyse, d’une part, la relation entre le développement des marchés boursiers et la croissance, l’attractivité et l’ef cience des marchés boursiers africains et examine, d’autre part, le potentiel d’économies d’échelle et/ou de gamme des dépositaires centraux des titres. Des résultats de l’étude, il ressort que les marchés boursiers africains sont, dans l’ensemble, peu attractifs des points de vue de la négociation des investisseurs et de la cotation des entrepri- ses, exceptions faites des bourses de Johannesburg et d’Ile Maurice. La majorité des marchés présentent un potentiel d’économies d’échelle et connaissent néanmoins, des problèmes de gestion stratégique. La thèse révèle que, bien que le développement du marché boursier joue un rôle dans la croissance économique, les marchés boursiers, captés par les indicateurs (scores d’attractivité des entreprises et des investisseurs) stimulent davantage la croissance que lorsqu’ils sont captés par des indicateurs traditionnels (la capitalisation boursière au PIB et le turnover). On peut con- clure qu’il ne suf t pas pour un pays africain de posséder un marché boursier pour béné cier d’un quelconque effet de levier de ce marché sur sa croissance économique, mais qu’il faudrait que ce marché soit performant, compétitif et attractif pour les entreprises et les investisseurs. Dans ce con- texte, la création des marchés boursiers en Afrique ne devrait plus reposer sur des considérations de mode, mais devrait répondre à des besoins et à des perspectives de concurrence prometteuse de développement et de croissance économique. [less ▲]

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See detailAnalyse des propriétés anti-tumorales des exosomes endothéliaux dans le cancer du sein suite au transfert du microARN miR-503
Bovy, Nicolas ULg

Doctoral thesis (2015)

L’angiogenèse est un processus essentiel au développement tumoral ainsi qu’à la dissémination des métastases. De plus, il a été démontré ces dernières années que les miARN, des ARN non codant d'une ... [more ▼]

L’angiogenèse est un processus essentiel au développement tumoral ainsi qu’à la dissémination des métastases. De plus, il a été démontré ces dernières années que les miARN, des ARN non codant d'une vingtaine de nucléotides régulant l’expression des gènes au niveau post-transcriptionnel, jouent un rôle important dans divers processus tumoraux. Ils ont en outre été détectés dans plusieurs fluides biologiques, protégés de la dégradation dans des microvésicules, les exosomes. Cependant, à l’heure actuelle, aucune information n’est connue sur le rôle des exosomes endothéliaux et des miARN qu’ils contiennent sur la croissance tumorale. Au cours de ce travail, nous avons pour la première fois mis en évidence l’existence d’un transfert de miARN des cellules endothéliales vers les cellules tumorales par l’intermédiaire d’exosomes. Nous avons ensuite identifié un miARN, miR-503, dont l’export dans ces microvésicules est modifié en conditions tumorales. L’analyse de la fonction du miARN dans les cellules tumorales de cancer du sein montre qu’il possède des propriétés anti-tumorales en réduisant la prolifération et l’invasion. Nous avons également observé que le miR-503 d’origine endothéliale génère les mêmes effets. Pour expliquer ces résultats, deux cibles du miARN ont été identifiées, CCND2 et CCND3. De plus, l’inhibition de ces dernières conduit au même phénotype qu’une surexpression de miR-503. Nous avons ensuite voulu déterminer si le niveau plasmatique de ce miARN était modulé chez des patientes atteintes de cancer du sein. Nos analyses révèlent une augmentation du niveau sanguin de miR-503 à la suite d’un traitement par chimiothérapie néoadjuvante. Nous avons de plus observé que des cellules endothéliales soumises aux mêmes agents chimiothérapeutiques sécrètent activement du miR-503 dans leurs exosomes. Il semble également que le changement phénotypique induit par miR-503 sur les cellules tumorales modifie leur production en facteurs angiogènes ce qui mène, en retour, à une inhibition de l’angiogenèse. Ces résultats montrent que miR-503 est un miARN anti-tumoral sécrété dans les exosomes de cellules endothéliales. Celui-ci provoque l’inhibition de la prolifération et de l’invasion de cellules tumorales du cancer du sein en ciblant CCND2 et CCND3. Ce processus pourrait être complémentaire des effets directs générés par la chimiothérapie sur la tumeur et favoriser la réponse de l’hôte dans le traitement de la maladie. [less ▲]

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See detailDispositifs de conservation écorégionale et droits indigènes dans l’Amazonie Bolivienne: Les cas des Peuples du Madidi et Pilón Lajas
Marquez Guerra, José Francisco ULg

Doctoral thesis (2015)

The apparatus of conservation at the ecoregional scale integrating natural landscape and cultural landscapes in the Amazon basin has been introduced by international conservation NGOs since the beginning ... [more ▼]

The apparatus of conservation at the ecoregional scale integrating natural landscape and cultural landscapes in the Amazon basin has been introduced by international conservation NGOs since the beginning of the 90s when the term hotspot was invented to designate the importance of "mega-diversity "of tropical forests for the survival of humanity. The representation of environmental problems in the Amazon region as serious threats to life on the planet entered the political agenda of the international community becoming a matter of priority attention. To find solutions to this expanding threat, scientists, activists and interested parties have reflected on some formulas, innovative programs and strategies in order that cooperation and international aid could favor the action of effective conservation and sustainable development. The problem of resource degradation of biodiversity, and the loss of the values of cultural diversity of Amazonian peoples is since then conceived as a challenge that goes beyond national political interests, becoming a global issue. Bolivia was a breeding ground for these pioneering efforts, they have made a pragmatic view of international aid with new tools and effective techniques to combat emerging threats, one of them are financial mechanisms for conservation planning. These have entered the Bolivian legal system from the 80 which coincides with the modernization of the state, an ambitious development plan supported by the implementation of neoliberal measures to promote economic growth, administrative decentralization as a new form to exercise power by delegating powers to the departmental and municipal levels, popular participation, as legitimacy methodology, defining local actors and regional planning policy as a useful management of natural resources for sustainable development. International actors of conservation, a group of scientific elite and environmental activists in the country and leaders of local indigenous movements have played an important role before and after this neoliberal modernization in the implementation of an ecorregional conservation apparatus in the Bolivian Amazon. The objective of this transdisciplinaria research, is an ethnographic description, based on the theoretical and methodological repertoire of legal anthropology and sociology of ANT Translation, of how the practices and strategies of conservation at the ecoregional scale through its technical, financial and legal instruments configure the territories, affect social relations and transform representations and practices of the nature of Amazonian peoples Mosetene, Tsimane' Tacana, Quechua-Tacana and Leco. The traditional spaces of these peoples are in total or partially overlapping with the current Natural Park and Integrated Management Area Madidi and Biosphere Reserve and Indigenous Territory Pilón Lajas implemented as protected areas during the 90 In this context, challenges and current controversies looming over the planning and use of space at different scales between actors of the policies of sustainable development and conservation, local political elites and indigenous peoples. [less ▲]

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See detailUncoupled and coupled hydrogeophysical inversions of seawater intrusion and geothermal hydrologic models
Beaujean, Jean ULg

Doctoral thesis (2015)

Most of humans live in coastal and alluvial plains. Sustainable water supply systems are essential for drinking water production while long-term groundwater access ensures its geothermal use. Owing to ... [more ▼]

Most of humans live in coastal and alluvial plains. Sustainable water supply systems are essential for drinking water production while long-term groundwater access ensures its geothermal use. Owing to climate change and anthropogenic activities, groundwater resources will be increasingly threatened throughout the twenty-first century. In the context of over-development, any effort to overcome groundwater mining at the expense of better understanding groundwater management problems may be misguided. A combination of robust measuring technologies and reliable predictions based on numerical models are necessary to estimate better hydrogeological parameters. Sparse and continuous data are increasingly being used conjunctively in hydrogeological modeling and inverse calibration to alleviate extrapolation and subjective interpretation. In hydrogeology, electrical resistivity tomography (ERT) gives quantitative and qualitative information on salinity and temperature distribution. ERT offers a means for mapping the subsurface hydrogeological structures and the hydrologic process dynamics in both space and time. The integration of ERT data to hydrogeological calibration is particularly suited to define the hydrogeological models quantitatively and qualitatively. In a deterministic framework, hydrogeophysical inversion methods may be particularly useful for predictive analysis and assessment of groundwater pre-emptive management strategies. This work focuses on calibrating physically-based and spatially distributed groundwater flow and transport models with non-to minimally invasive electrical tomography. The general objective is to provide better estimates of hydrogeological parameters on two relevant problems: seawater intrusion in coastal areas and geothermal energy in shallow environments. We compare methods to integrate quantitatively ERT data, possibly other hydrologic or geological data, with existing information to hydrogeological models. Two hydrogeophysical inversion schemes are developped and a thorough comparison of an uncoupled and a coupled quantitative approach based on the use of surface ERT only is performed. The uncoupled hydrogeophysical inversion involves constraining hydraulic parameters using geophysically-derived data and first requires a geophysical inversion, after which the geophysical parameters are converted to hydrologic data through a petrophysical relationship. The inverse hydrological calibration is then performed on these inferred hydrological data. The coupled hydrogeophysical inversion involves constraining hydraulic parameters using geophysical data through a forward hydrogeophysical model in which the hydrologic data are converted to resistivities through a petrophysical relationship. A geophysical forward problem is then solved for the geophysical data. The inverse hydrological calibration is performed on the inferred geophysical observations. In both schemes, we show that an independent geophysical inversion is required to delineate heterogeneous bodies. In this context, we study how to derive informative content of ERT images and therefore ERTderived hydrologic data and ERT-derived geometry. We show that a quantitative appraisal (the cumulative sensitivity) must be used as a proxy for filtering areas correctly resolved. Our developments are demonstrated on several benchmark SWI models (numerical and analytical), a thermohydrologic model and a field test. We show that the reliability of estimated SWI model parameters with the uncoupled approach depends on ERT image appraisal, on geophysical data collection strategy and hydrogeological model conceptualization. The ERT image appraisal plays a key role in retrieving high quality ERT-derived data and helps discriminate different measurement arrays. It is particularly useful in preventing the integration of noise-related artefacts in the conceptualization. We endeavor to quantify the modeling error by a thorough comparison of different strategies to assess the effect of decreasing model conceptual errors to hydrogeological calibration. In the SWI analytical models, we highlight the subjectivity of the uncoupled approach due to the nature of the required hydrologic data (sharp interface). We demonstrate that the conjunctive use of an image appraisal tool with the well-known Ghyben-Herzberg solution is needed to infer reliable ERT-derived observation data. We further demonstrate that a SWI analytical solution may be used to calibrate an equivalent hydraulic parameter based on an ERT dataset generated from a density-dependent groundwater flow model. In the thermohydrologic model, we show that the effectiveness of the uncoupled scheme in calibrating heat transport parameters may be hampered due to the regularization constraint in the geophysical inversion. We demonstrate the importance of a noise level-related filter on the time-lapse ERT images aimed at properly quantifying the spatio-temporal ERTderived temperature changes. We also advocate the use of a physically-based constraint on the ERT-derived temperatures to account for spatial mixing of waters and to cope indirectly with the smoothing effect in the ERT images. In each application, the coupled approach significantly prevails over the uncoupled scheme in terms of reliability of the parameter estimates when no model conceptual error exists. [less ▲]

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See detailLa dynastie belge et la science, 1909-1959
Pirot, Pascal ULg

Doctoral thesis (2015)

The project consists in investigating the role of the Belgian dynasty in scientific development since the beginning of the reign of king Albert I (1909), until the establishment of the National Council ... [more ▼]

The project consists in investigating the role of the Belgian dynasty in scientific development since the beginning of the reign of king Albert I (1909), until the establishment of the National Council for Science Policy (CNPS) in 1959, during king Baudouin's reign, following the publication of the work of the "National Commission on Science" which released its conclusions in the same year. The study deals with the action of the sovereign and the networks he formed with his entourage (the queen, the crown prince, the advisers of the court, some close relations of the king, the ministers in charge of scientific affairs) in the field of science, along various research themes; how these people saw the role of science in society; what influence they had in the development of science (institutions, initiatives, projects); what relationships existed between the dynasty and the scientific institutions; what the relationships between the dynasty and the Congo were in the realm of science. This perspective, which focuses on three Belgian sovereigns of the twentieth century, should make it possible to assess the development and progressive implementation of the "science policy". To date, no study has been specifically devoted to this topic. [less ▲]

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See detailLa simulation thermo-aéraulique du bâtiment : Validation et développement d’une approche couplée CFD-Multizone pour l’étude de la modélisation du phénomène de surchauffe estivale en Belgique
Barbason, Mathieu ULg

Doctoral thesis (2015)

For decades, growing interests in environmental and buildings energy performance concerns lead architects and building engineers to develop new skills and to get used to advanced simulation tools. Among ... [more ▼]

For decades, growing interests in environmental and buildings energy performance concerns lead architects and building engineers to develop new skills and to get used to advanced simulation tools. Among them, Multizone models and Computational Fluid Dynamics (CFD) models are increasingly used to solve problems of building physics. This Thesis reports the development of a new and optimized tool based on the coupling of these two tools and its application to a typical Belgian two-storey house. Indeed, separately, these two tools have significant advantages and disadvantages : • Multizone models are based on the hypothesis that the temperature is uniform in every simulated zone which implies that they are not suited for large spaces. However, in small spaces, Multizone models generate accurate results in a small amount of time. • CFD models are very accurate, independently of the size of the room or the type of physical phenomena encountered. However, it is also well known that CFD simulation are time and resources consuming. Consequently, it is not possible to use it for a long term study. This Thesis will first introduce these approaches and discuss their validity field. In order to do this, a validation process has been developed to assess the ability of CFD to model accurately physical phenomena at different study scales. This Thesis will then discuss the coupling scheme developed in this study, based on experimental results of a two-storey house in Belgium. Different coupling level will be studied in order to understand deeply needs of such approach. Eventually, it will be shown that coupling approach can drastically improve overheating prediction for buildings even for a long term simulation. Thanks to this new tool, building actors may design optimized cooling strategies while maximizing occupants comfort. [less ▲]

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See detailDroit du travail congolais face à l'usage des technologies de l'information et de la communication: la problématique de nouveaux défis
Mbungu Tsende, Lievin ULg

Doctoral thesis (2015)

La thèse s’intéresse, d’une part, aux bouleversements entraînés par les technologies de l’information et de la communication dans le monde du travail congolais et, d’autre part, aux solutions qu’ils ... [more ▼]

La thèse s’intéresse, d’une part, aux bouleversements entraînés par les technologies de l’information et de la communication dans le monde du travail congolais et, d’autre part, aux solutions qu’ils appellent compte tenu du contexte socioculturel, économique, psychologique et technologique propre à la R.D.Congo. Il s’agit d’une étude qui tend non seulement à démontrer que le contexte actuel, marqué par l’emprise irréversible des TIC sur les relations de travail, remet partiellement en cause le cadre juridique et le modèle classique ou traditionnel congolais de réglementation des rapports entre employeur et travailleur, mais aussi à proposer, de lege ferenda, les aménagements susceptibles de remédier à cette situation. [less ▲]

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See detailDetection of past and future atmospheric circulation changes over the North Atlantic region with the help of an automatic circulation type classification
Belleflamme, Alexandre ULg

Doctoral thesis (2015)

Future projections of the atmospheric circulation over the Northern Hemisphere high latitudes, especially the North Atlantic, have high uncertainties and some of the projected changes are opposed to ... [more ▼]

Future projections of the atmospheric circulation over the Northern Hemisphere high latitudes, especially the North Atlantic, have high uncertainties and some of the projected changes are opposed to circulation changes that have been observed since the 2000s. In this thesis, we focus on three particular aspects of the past and projected future summertime atmospheric circulation over the broader North Atlantic region. First, we analyse whether the 2007-2012 summertime anticyclonic anomaly over the Beaufort Sea, the Canadian Arctic Archipelago, and Greenland might rather be due to global warming or to the internal variability of the atmospheric circulation by putting it in perspective with the circulation variability over the last 150 years given by five reanalysis datasets. Then, this analysis is extended for the future circulation projected towards 2100 by CMIP3 and CMIP5 General Circulation Models (GCMs) over Greenland. Finally, we evaluate the impact of the uncertainties of the future atmospheric circulation projections on the mitigating or enhancing influence of the summertime circulation changes on temperature and precipitation over Europe. We use an automatic circulation type classification to analyse in detail the atmospheric circulation changes by grouping similar daily SLP (mean sea level pressure) or Z500 (500 hPa geopotential height) fields into homogeneous circulation types. It appears that the choice of the index, on the basis of which the days are grouped together, strongly influences the characteristics of the circulation types and the kinds of circulation changes that can be detected. In comparison with Euclidean distance and pressure gradient-based indices, correlation-based indices, especially the Spearman rank correlation, are the most suitable indices when focusing on the circulation pattern. Over the Arctic region, four periods with circulation anomalies similar to that of 2007-2012 (i.e. a summertime anticyclonic anomaly over the western Arctic region) have been detected over the last 150 years, despite a higher uncertainty of the circulation given by the reanalyses due to the scarcity of observational data before 1940. Nevertheless, the 2007-2012 anomaly appears to be exceptional and several connexions with other variables, such as the North Atlantic Oscillation index and sea ice loss, suggest that it could be part of a major climatic anomaly extending beyond the Arctic region. However, the occurrence of similar periods in the past and the influence of several external and internal forcings do not allow us to attribute it to global warming. The future summertime atmospheric circulation projected by GCMs over Greenland confirms this conclusion. In fact, no significant circulation pattern changes are simulated towards 2100, besides a generalised Z500 increase caused by the projected warming. Since GCMs are able to simulate atmospheric circulation changes over other regions and since the atmospheric circulation itself is influenced by other variables, such as sea ice or snow extent, which are already impacted by long-term changes, we conclude that the 2007-2012 anomaly could rather be attributed to the internal variability of the climatic system. Finally, we evidence that projected future atmospheric circulation changes impact on the SLP and precipitation changes simulated over Europe towards 2100 for summer. Over north-western Europe, these circulation changes could mitigate the SLP decrease by around 50 % and cancel out the precipitation increase. Nevertheless, high uncertainties among the GCMs on the magnitude and even on the sign of these changes cast doubt on the reliability of these projections. On the other hand, future atmospheric circulation changes are not projected to affect significantly the warming and drying simulated for the next decades over the Mediterranean region and eastern Europe. [less ▲]

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See detailLes plus anciens livres latins de poésie: étude codicologiue, paléographique et contextuelle des manuscrits datés du Ier siècle avant notre ère au VIe siècle.
Macedo, Gabriel ULg

Doctoral thesis (2015)

Codicological, paleographic and contextual study of the 34 oldest manuscripts and fragments containing latin poetry.

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

Doctoral thesis (2015)

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

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

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See detailModelling the dynamics of European ecosystems from the early Holocene to the end of the 21st century with the CARAIB dynamic vegetation model
Dury, Marie ULg

Doctoral thesis (2015)

With the current climate change as background, we worked with the dynamic vegetation model CARAIB (CARbon Assimilation In the Biosphere) to study the functioning and dynamics of European ecosystems under ... [more ▼]

With the current climate change as background, we worked with the dynamic vegetation model CARAIB (CARbon Assimilation In the Biosphere) to study the functioning and dynamics of European ecosystems under changing climatic conditions from the beginning of the Holocene to the end of the 21st century. Originally designed to study the role of vegetation in the global carbon cycle and to reconstruct steady state vegetation distributions under current, past and future climatic conditions, we adapt the CARAIB model to perform transient simulations in order to assess vegetation response to changing climate. For this, we improved the demographic processes represented in the model: the conditions for plant establishment, the response to stresses, the competition between species, the species migration, etc. This new version of the model is first described and its main outputs are evaluated using site-based observations, but primarily remote sensing products. The first study carried out with the new version of CARAIB assessed the response of European forest ecosystems to 21st century climate. The classification of the European vegetation in Bioclimatic Affinity Groups (BAGs, Laurent et al., 2008), based on species traits and climatic tolerances and requirements, as well as the fire module recently implemented were for the first time used in future transient projections. The model was first driven by the ARPEGE/Climate model to illustrate and analyse the potential impacts of climate change on forest productivity and distribution as well as fire intensity over Europe under forcing from different IPCC emission scenarios (B1, A1B and A2). The vegetation model projects for the future more frequent and severe droughts in southern Europe. In these areas, the model indicates that interannual variability of net primary productivity might strongly increase as well as wildfire frequency and intensity, which may have large impacts on vegetation density and distribution. In northern Europe and in the Alps, with reduced temperature variability and positive soil water anomalies, NPP variability tends to decrease. The potential CO2 fertilizing effect was studied assuming constant and increasing atmospheric CO2 concentration in the vegetation model. To quantify the uncertainties in the climate projections and in their potential impacts on ecosystems, the vegetation model was also driven by three regional climate models (KNMI-RACMO2, DMI-HIRHAM5 and HC-HadRM3Q0 RCMs) from the European Union project ENSEMBLES. We continued further the analysis representing the European vegetation at the scale of individual species. A set of 99 species (47 herbs, 12 shrubs and 40 trees) have been prepared in such a way that each BAG of plants used in the first part of this work is represented by several of these species. This ensures to provide a full set of species with the major ecosystem functions represented. Like for the BAGs, the bioclimatic limits of the species were obtained by overlapping species distribution from the Atlas Florae Europaeae (AFE) with climatic data. Since the first study highlighted the importance of climatic variability on plant functioning, we used here a 30-yr time series (and not average climate as usually) to determine species establishment and survival conditions. The comparison between the modelled distributions obtained with new climatic thresholds and observed species distribution reveals that taking a longer climatic time series into account improves the predictions of species spatial pattern. Using this improved representation of current species requirements, we projected potential shifts in species distributions for the end of the century. We spatially evaluated the suitability for species establishment and stresses conditions as well as the disappearance and the potential appearance of species. 18% of tree species and 22% of herb and shrub species (respectively 30% and 64% if the CO2 fertilization effect on species is not taken into account) might experience a loss of 30% or more of their current distribution. Finally we combined different model outputs in an original index evaluating the risk of ecosystem disruption to assess the vulnerability of species and ecosystems to future climate change. The highest values of the index are found in southern Europe indicating that the amplitude of the expected ecosystem changes largely exceeds current interannual variability in this area. If climate is one of the main drivers of species dynamics, rapid climate changes as projected for the 21st century might prevent species to track suitable climatic conditions and fill their potential ranges impeded by dispersal capacity. To assess the actual response of vegetation to climate change, we introduced a species migration module in the dynamic vegetation model. Its calibration and evaluation have been performed on the Holocene period considered as an interesting homologue to current climate change, even if the change rate must have been lower. With the module, we studied the postglacial re-colonization of Europe by two tree species Fagus sylvatica and Picea abies. Using maximum potential migration rates (381 and 450 m yr-1 for beech and spruce) calculated by a species distribution model dealing with demographic and dispersal traits, we evaluated with the dynamic vegetation model the involvement of inter-specific competition but also of high climatic variability on species spatio-temporal dynamics. Considering these abiotic and biotic variables in the migration processes resulted in mean migration rates of 91 (± 38) and 131 (± 73) m yr-1 respectively for Fagus sylvatica and Picea abies. If the comparison with palaeorecords demonstrates the ability of such an approach to reasonably replicate the regional features of the species spatio- temporal progressions, the objective was not to reproduce accurately postglacial species history (still not well known and understood) but rather to determine the relative role of some environmental variables on the migration of the two species through different migration scenarii. It appeared that Holocene beech migration might have been strongly affected by interspecific competition while it is climatic conditions and their variability that might have conditioned the spruce migration. With the different scenarios, we showed that mono-causal explanations cannot however explain the observed timing and pattern at the European scale and we rather give preference to a combination of climate, dispersal and competitive factors, the potential role of anthropogenic disturbances being not studied here. [less ▲]

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See detailGreen strategies applied to the synthesis of polymer particles for protein delivery
Alaimo, David ULg

Doctoral thesis (2015)

With the recent progresses in biotechnology that enable the production of various peptides and proteins, there is a growing interest for their use as therapeutic agents. Indeed, since the introduction of ... [more ▼]

With the recent progresses in biotechnology that enable the production of various peptides and proteins, there is a growing interest for their use as therapeutic agents. Indeed, since the introduction of the first recombinant therapeutic protein, human insulin, 30 years ago, the interest for pharmaceutical proteins have increased remarkably for various therapeutic purposes. Nevertheless, several challenges still remain such as the preservation of the quite fragile complex protein structure of these proteins to warrant their therapeutic activity after storage and administration into the body. Protecting them against chemical/enzymatic degradation from the environment is a prerequisite to efficiency. To reach this goal and prolong/trigger the release of therapeutic proteins in the body, different carriers were developed and investigated. Among them, polymer nanogels and microcpasules appear as quite promising systems. The thesis focuses on the preparation of novel carriers for protein delivery while using “green” strategies. More precisely, protein carriers are produced by two approaches. The first one investigates the preparation of hydrophilic nanogels by free radical dispersion polymerization of hydroxyethyl methacrylate (HEMA) in supercritical carbon dioxide. The development of dedicated stabilizers efficient in this green medium is thus first considered particularly focussing on the study of the influence of the stabilizer architecture. Then, the optimized candidate is used for the size- controlled nanogels preparation. A strategy allowing the removal of the hydrophobic component of the stabilizer is then investigated based on the synthesis of a photocleavable copolymer. The performances of these as-obtained novel nanogels to load and release proteins is then investigated. In a second approach, the synthesis of protein-loaded microcapsules offering a tunable permeability in response to the external glucose concentration is investigated. For that purpose, the layer-by-layer assembly of dedicated copolymer polyelectrolytes including glucose-sensitive diol/boronic acid bonds was performed on the surface of protein-loaded calcium carbonate particles. After dissolution of the calcium salt, microcapsules able to tune the release of the encapsulated protein in response to glucose concentration are obtained. [less ▲]

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See detailEpidemiology of brucellosis in humans and domestic ruminants in Bangladesh
Rahman, AKM Anisur ULg

Doctoral thesis (2015)

Background Brucellosis is an ancient and one of the world’s most widespread zoonotic diseases affecting both, public health and animal production. It is endemic in many developing countries of Asia ... [more ▼]

Background Brucellosis is an ancient and one of the world’s most widespread zoonotic diseases affecting both, public health and animal production. It is endemic in many developing countries of Asia, Africa and Latin America including Bangladesh. Since the first report in 1970, a lot of brucellosis seroprevalence reports are available in cattle, goats, sheep and humans in Bangladesh. Most of the previously reported prevalence studies were based on non-random samples, which may not give a true representation of the status of the disease in respective populations. Some authors also investigated the risk factors in cattle. The tests used for the diagnosis of brucellosis in domestic ruminants and humans are imperfect and their performance was not evaluated in Bangladesh. The true prevalence of brucellosis in domestic ruminants is not known and is essential for analyzing the impact of this disease in domestic ruminants in Bangladesh. Indeed, when diagnostic tests are used without evaluating their performance in a context usually generate unreliable results, which in turn may lead to wrong epidemiological inferences. In addition, information on risk factors of brucellosis in humans and animals is also scarce. Moreover, the different species of Brucella prevalent in animals is scarce and not known in humans in Bangladesh. The overall objective of this thesis was to investigate the epidemiology of brucellosis in humans and domestic ruminants in Bangladesh in terms of the evaluation of commonly used diagnostic tests, estimation of true prevalence, identification of risk factors and detection of Brucella species in order to provide information that will guide the selection of appropriate control strategies. Study design and data analysis Sampling To collect random samples of animals a system of map digitization and selection of one geographical point from selected unions (Sub-Upazilla) using a hand held GPS machine was used. Blood (milk also where applicable) samples were then collected from livestock farmers and their animals within 0.5 km of the selected points. A convenient blood sample of butchers, dairy hands and veterinary practitioners were collected from Dhaka and Mymensingh districts. The sera of pyretic humans were collected from Mymensingh Medical College hospital randomly once in a week. Random milk samples were collected from Sirajgonj and Chittagong districts. Systematic random milk and blood samples of cattle including breeding bulls (semen also) of central cattle breeding and dairy farm (CCBDF) were also collected. Milk and blood samples of gayals of a herd in regional Bangladesh Livestock Research Institute at Naikhonchari, Bandarban were also collected. Convenient samples of placenta and vaginal swabs were also collected from Mymensingh district. Data collection and Analysis Data on serology was generated by using Rose Bengal test (RBT), Slow Agglutination test (SAT) /Standard tube agglutination test (STAT) (animals/humans) and indirect enzyme linked immunosorbent assay (iELISA). Animal, their herd level data and human data on potential risk factors were collected using a pretested questionnaire. The data was stored in Microsoft Excels worksheets and transferred to respective software for analysis. To estimate true prevalence and evaluate three conditionally dependent serological tests, Bayesian latent class models were used. Random effect and Firth’s logistic regression analyses were used to determine the risk factors of human brucellosis. The STATA, R and OpenBUGS softwares were used for data analyses. Staining, culture, genus and species-specific real time PCR assays were applied to isolate and to detect Brucella Spp./DNA in seropositive human sera and animal samples. Main results: Only 0.29% (95% CI: 0.06-0.86) cattle were acutely infected whereas 0.49% (95% CI: 0.16- 8 1.1) were chronically infected with brucellosis in Mymensingh. On the other hand, in CCBDF 15.58% (95% CI:11.89-19.89) cattle were acutely infected with brucellosis and only 3.2%(95%CI: 1.63-5.72) were chronically infected. The true prevalence of brucellosis among cattle in Mymensingh and CCBDF were 0.3% (95%CI: 0.03-0.7) and 20.5% (95% CI: 16.4-26.3) respectively. The performance of iELISA was best in both Mymensingh and CCBDF with the sensitivity of 90.5% and 91.3% and specificity of 99.3% and 99.2% respectively. The performance of RBT was better in Mymensingh than CCBDF with 81.0% and 76.1% sensitivity and 99.0% and 95.6% specificity respectively. Similar to RBT, the performance of SAT was also better in Mymensingh than CCBDF with 63.5% and 79.7% sensitivity and 98.6% and 95.3% specificity respectively. Through this test validation study, a new cut-off of 5 IU/ml for iELISA was recommended both in low (as at Mymensingh) and high prevalence scenarios in cattle populations (as at CCBDF) for routine screening. It was recommended to do nothing for the control of bovine brucellosis under small-scale dairy and subsistence management systems in Bangladesh. However, vaccination should be applied in herds where the prevalence is very high as like CCBDF. The true prevalence of brucellosis in goats and sheep were estimated as 1% (95% CI): 0.7–1.8) and 1.2% (95% CI: 0.6–2.2) respectively. The sensitivity of iELISA was 92.9% in goats and 92.0% in sheep with corresponding specificities of 96.5% and 99.5% respectively. The sensitivity and specificity estimates of RBT were 80.2% and 99.6% in goats and 82.8% and 98.3% in sheep. The sensitivity and specificity of SAT were 57.1% and 99.3% in goats and 72.0% and 98.6% in sheep. The prevalence of brucellosis in occupationally exposed people (HROG) using three tests was observed to be 4.4% based on a parallel interpretation. The results of the multiple random effects logistic regression analysis with random intercept for district revealed that the odds of brucellosis seropositivity among individuals who had been in contact with livestock for more than 26 years was about 14 times higher as compared to those who had less than 5 years of contact with livestock. In addition, when the contact was with goats, the odds of brucellosis seropositivity were about 60 times higher as compared to when contact was with cattle only. The seroprevalence of brucellosis among patients with pyrexia of unknown origin (PUO) was estimated to be 2.7% (95% CI: 1.2-5.2). The age, residence, type of patient, contact with animals, type of animal handled, arthralgia and backache were found to be significantly associated with a positive serological result in bivariable Firth’s logistic regression. Brucella abortus was detected from seropositive pyretic patients. Conclusion: The true exposure prevalence of brucellosis in cattle under small-scale dairy and subsistence/backyard management systems is very low (0.3%; 95% CI: 0.03-0.7). The active/acute infection is also very low (0.29%: 95% CI: 0.06-0.86) and similar to true exposure prevalence. The brucellosis in cattle under such management system is naturally controlled and further control program is not recommended considering the poor socioeconomic conditions. The true exposure prevalence of brucellosis in CCBDF is very high (20.5%; 95% CI: 16.4-26.3). The acute infection in this farm is also very high (15.58%; 95% CI: 11.89-19.89). Immediate control measures by initiating calf hood (female calf) vaccination are recommended to protect a valuable herd which also provides frozen semen for artificial insemination all over the country. The SAT and iELISA may simultaneously be applied to know the stage of brucellosis infection in domestic ruminants in high prevalence scenarios. The true exposure prevalence of brucellosis in goats and sheep are also low and around 1%. Due to lower positive predictive value, these test results should be interpreted with caution to avoid misleading information. Breeding bulls used for artificial insemination all over the country were found to be infected with brucellosis. Brucellosis is not a serious problem for the general population in Bangladesh as drinking raw milk and milk products is unusual and not a risk factor. The apparent prevalence of brucellosis in high risk occupationally exposed people (4.4%; 95% CI: 2.8-6.6) and in pyretic patients (2.7%; 95% CI: 1.2-5.2) are also low. The RBT may be applied as a screening test in humans having signs and symptoms of brucellosis along with the history of animal contact. In case of suspicion, genus or species specific rt PCR may be applied for confirmation. Only B. abortus DNA was amplified from 19 seropositive human samples (both HROG and PUO) and six animal samples (3 cows milk, one goat milk, one gayal milk and one bull semen). No Brucella like organism was observed under microscope in stained smears. Similarly, no Brucella organism was isolated from any of the clinical samples. [less ▲]

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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See detailImaging the mechanisms involved in abdominal aortic aneurysms rupture; a step towards patient-specific risk assessment

Doctoral thesis (2015)

Introduction The general context of this dissertation is to evaluate patient-specifi c approaches to the risk of rupture of abdominal aortic aneurysm (AAA), using imaging techniques with ability to assess ... [more ▼]

Introduction The general context of this dissertation is to evaluate patient-specifi c approaches to the risk of rupture of abdominal aortic aneurysm (AAA), using imaging techniques with ability to assess biological processes. Following a thorough description of available imaging techniques, our work is divided in two main research objectives, namely: (i) to provide greater clinical value to existing but unproven imaging concepts, and (ii) to suggest new concepts for improved AAA risk of rupture assessment. Methods The fi rst research objective evaluated how far imaging biological activities using 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) and modeling wall stress using fi nite element simulations (FES) may help clinical decisionmaking in patients with AAA, and what would be their incremental value as compared to diameter-based patient management algorithms. On a patient basis, clinical outcomes were evaluated with regard to FDG PET and FES signaling. Further, the concept of AAA risk-equivalent diameter using FES was described and retrospectively validated using data from large multicenter trials. The second research objective included the assessment of the biological activities of the intraluminal thrombus (ILT) and the demonstration of its deleterious role in AAA using multimodality imaging. A special emphasis was put on the ability of magnetic resonance imaging (MRI) to monitor the biological activities of ILT without exogenous contrast, by evaluating its iron content. Results Increased FDG uptake was a diameter-independent marker of AAA-related events over 2 years. Missing dichotomy prevented such a fi nding for increased wall stress, although its correlation with increased FDG uptake indicates a potentially comparable value in terms of risk management. Wall metabolism is infl uenced by patient-specifi c susceptibility factors, indicating hereditary or acquired alteration of the biological responses to wall stress. The concept of risk-equivalent diameters on FES links biomechanical estimates to basic conclusions drawn from large diameter-based clinical AAA trials. Our retrospective and diameter-adjusted validation analysis verifi ed that biomechanical risk indicators are higher in ruptured than non-ruptured AAAs. Part of the FDG uptake is associated with biological activity along the luminal surface of the ILT, where we experimentally demonstrated phagocytosis of superparamagnetic iron oxide on MRI , both ex vivo and in vivo. This phagocytosis is correlated with the abundance of leukocytes and proteolytic activity. In addition, unenhanced MRI appearances resulting from the endogenous iron distribution within ILT also relate to these biological activities. Lastly, multimodality imaging was used to confi rm the concept of the deleterious role of the ILT in AAA growth in a model of AAA by infusion of elastase in the rat. Conclusion MRI and FDG PET are capable of evidencing and quantifying in vivo some of the notoriously deleterious biological processes taking place in the aneurysmal sac, especially related to the entrapped phagocytes and red blood cells in ILT and the periadventitial infl ammatory response. The central role played by ILT and its biological activities was demonstrated in vivo using several imaging techniques. The clinical value of imaging these biological activities is epitomized by a diameterindependent 2-year increased risk of event in AAA with increased wall metabolism. [less ▲]

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See detailEtude de la reconstitution immunitaire après greffe de cellules souches hématopoïétiques : focus sur la fonction thymique et les lymphocytes T régulateurs
HANNON, Muriel ULg

Doctoral thesis (2015)

L’allogre e de cellules souches hématopoïétiques, après conditionnement myéloalbatif ou non, est devenue une option de choix dans le traitement des maladies hématologiques malignes ou génétiques ... [more ▼]

L’allogre e de cellules souches hématopoïétiques, après conditionnement myéloalbatif ou non, est devenue une option de choix dans le traitement des maladies hématologiques malignes ou génétiques. Malheureusement le succès de ce traitement se trouve trop souvent entaché par des complications majeures telles que les infections ou la maladie du greffon contre l’hôte (GVHD), dans laquelle les cellules du donneur attaquent l’organisme du receveur. La reconstitution d’un système immunitaire fonctionnel, notamment via le thymus, est une étape clef dans la résolution de ces deux complications et l’utilisation de lymphocytes T régulateurs semble très prometteuse dans la lutte contre la GVHD. Le présent travail vise donc à étudier la reconstitution du système immunitaire après allogreffe sous trois angles différents, en nous focalisant sur la fonction thymique et l’influence des lymphocytes T régulateurs (Treg). Dans la première partie, nous évaluons la reconstitution immunitaire à long terme après greffe non-myéloablative et montrons que la néo-génération de lymphocytes T par le thymus s’effectue à partir du jour 100 chez les patients de moins de 60 ans alors qu’au delà de cet âge, elle est quasiment absente. Nous établissons également que la GVHD chronique (cGVHD) sévère possède des effets extrêmement délétères sur le thymus. Étant donné l’impact de la cGVHD sur le thymus et la reconstitution immunitaire, nous avons voulu comparer l’impact, sur ces deux paramètres, d’un conditionnement nonmyéloalbatif censé réduire la GVHD et composé d’une irradiation lymphoïde totale et d’anticorps anti-thymocytes (TLI-ATG) par rapport au conditionnement classique consistant en une irradiation corporelle totale associée à de la fludarabine (TBI-Flu). Il ressort de cette étude que, bien que réduisant de manière significative l’incidence de cGVHD, le conditionnement TLI-ATG altère fortement la reconstitution du système immunitaire et impacte négativement le taux de rechute/progression chez les patients traités. Enfin, toujours dans le but de réduire le taux de GVHD post-greffe, nous avons choisi d’examiner l’impact des Treg comme traitement de la xGVHD. Dans ce but, nous montrons qu’une sélection de Treg humains, sur CliniMACS par déplétion CD8/19 et sélection CD25, fournit une population de cellules enrichies en Treg capable de retarder de manière statistiquement significative l’apparition d’une GVHD xénogénique induite par injection de PBMC humains (autologues aux Treg) dans un modèle pré-clinique chez la souris NSG. De plus, lorsque injectée sans les PBMC, cette population enrichie n’induit pas par elle-même de GHVD. [less ▲]

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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See detailPathogenesis of wildebeest-derived malignant catarrhal fever: lessons from micro-RNAs and the genome maintenance protein of alcelaphine herpesvirus 1
Sorel, Océane ULg

Doctoral thesis (2015)

Chez les gammaherpèsvirus, le genre Macavirus regroupe des virus associés au coryza gangreneux (CG) et des virus phylogénétiquement proches. Le CG est caractérisé par une maladie lymphoproliférative aigue ... [more ▼]

Chez les gammaherpèsvirus, le genre Macavirus regroupe des virus associés au coryza gangreneux (CG) et des virus phylogénétiquement proches. Le CG est caractérisé par une maladie lymphoproliférative aigue et fatale affectant de nombreux ruminants, dont le bovin. L’herpèsvirus alcélaphin 1 (AlHV-1) et l’herpèsvirus ovin 2 (OvHV-2) sont capables de persister à vie respectivement chez le gnou et le mouton, sans causer aucun signe clinique ni lésion. Lorsque ces virus sont transmis à d’autres ruminants sensibles, ceux-ci développent respectivement, la forme européenne (FECG) ou africaine du coryza gangreneux (FACG). L’impact économique de la FACG a été largement sous-estimé en Afrique sub-Saharienne ce qui traduit la nécessité de mieux comprendre les mécanismes à l’origine de la pathogénie de la FACG. Le développement de la FACG est étudié chez le lapin qui reproduit la maladie de manière comparable du point de vue macroscopique et histologique à ce qui a été décrit chez les bovins. Des études récentes ont montré que la FACG était associée à une sévère prolifération et infiltration de lymphocytes T CD8+ infectés latents dans la plupart des organes sans détection de particule virale infectieuse (Palmeira et al., 2013). De plus, la protéine de maintenance génomique (PMG) codée par l’ORF73 de l’AlHV-1 (aLANA), qui est responsable du maintien des épisomes viraux dans les cellules infectées, a été démontrée comme étant essentielle au développement de la FACG. Les ARNs non codants, comme par exemple les microARNs (miARNs), ainsi que les PMGs font partie des rares transcrits exprimés pendant la latence des gammaherpèsvirus. Les miARNs exprimés par les herpèsvirus jouent des rôles dans la régulation de la latence, la transformation tumorale des lymphocytes, le cycle cellulaire et l’immuno-évasion. Les PMGs sont responsables de la persistence épisomale dans les cellules infectées latentes au cours de la mitose tout en échappant à leur propre présentation, en contexte CMH-I, aux lymphocytes T cytotoxiques, un mécanisme nommé : immuno-évasion en cis. Ce travail reflète notre volonté de comprendre les mécanismes par lesquels l’AlHV-1 est capable de persister in vivo tout en restant indétectable par le système immunitaire. La première étude de cette thèse a été dédiée à l’identification des miARNs codés par l’AlHV-1 et de leurs rôles potentiels dans l’induction de la FACG. Nous avons identifié 36 miARNs potentiels dans des cellules infectées de veaux développant la FACG, parmi lesquels 32 étaient exprimés en deux groupes sur le brin complémentaire du génome. Après avoir validé l’expression de ces 32 miARNs, nous avons montré que la délétion du groupe comprenant 28 miARNs viraux n’affectait pas la croissance virale in vitro ni l’induction de la FACG chez les lapins. La deuxième étude traite de l’investigation de la propre inhibition, par aLANA, de sa présentation antigénique et du rôle potentiel de ce mécanisme dans le développement de la FACG avec l’aide du modèle lapin. Nous avons démontré que, tout comme ses orthologues, aLANA est capable d’inhiber sa propre présentation aux lymphocytes T cytotoxiques grâce à un mécanisme impliquant la diminution de sa propre synthèse protéique. Nous avons mis en évidence que la présence de la région riche en GE du domaine central répété de aLANA est responsable de ce mécanisme. Pour finir, nous avons généré une souche recombinante de l’AlHV-1 exprimant une protéine aLANA tronquée du domaine GE. Nous avons observé que l’absence de GE n’affectait pas la croissance virale in vitro et n’empêchait pas le développement de la FACG dans le modèle lapin. Ces résultats montrent que GE n’est pas essentiel pour la persistence virale ni la maintenance épisomale. Cependant, l’induction de la FACG a été significativement retardée chez 2 des 4 lapins infectés, ce qui suggère que la région GE de aLANA est potentiellement nécessaire à l’échappement de la réponse cytotoxique anti-virale pendant la FACG. Les macavirus sont capables de persister dans leur hôte naturel alors que la transmission du virus à d’autres espèces sensibles mène au développement de la FACG. Des études récentes ont placé la latence des gammaherpèsvirus au cœur de la pathogénie de la FACG. Il est intéressant de mieux comprendre le mécanisme par lequel l’AlHV-1 est capable de persister in vivo et d’induire la FACG tout en restant caché de la réponse immunitaire afin d’améliorer nos connaissances actuelles sur la pathogénie des macavirus, et plus généralement des gammaherpèsvirus. [less ▲]

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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

Doctoral thesis (2015)

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

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

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See detailMagnetic properties of structures combining bulk high temperature superconductors and soft ferromagnetic alloys
Philippe, Matthieu ULg

Doctoral thesis (2015)

The purpose of the present work is to determine experimentally and numerically how the magnetic flux density both inside and outside a large grain, bulk high temperature superconductor is modified when ... [more ▼]

The purpose of the present work is to determine experimentally and numerically how the magnetic flux density both inside and outside a large grain, bulk high temperature superconductor is modified when placed in the vicinity of axisymmetric ferromagnetic components. The investigated superconductors are bulk (RE)Ba2Cu3O7 cylinders of a few cm³. The ferromagnets are of various sizes and shapes, machined out of well characterized, soft magnetic alloys of high permeability. Both superconductor and ferromagnet have the same diameter and are cooled at the liquid nitrogen temperature (T = 77 K). The properties of the superconductor / ferromagnet (SC/FM) hybrid structures are investigated through surface (Hall probe) and volume measurements carried out in the fully magnetized remanent state and under complete cycles of field applied either parallel or perpendicular to the sample c axis. The design of a suitable volume characterization method for large samples and its validation through comparison with other measurements is part of the present work. Numerical models based on the Brandt and finite element methods are compared with the measurements and used to investigate configurations and physical quantities that are not accessible experimentally. We show that the ferromagnet acts as a magnetic short-circuit and creates a low reluctance path that drives the flux lines directly towards the edges of the superconducting magnet. The zone above the ferromagnet is shielded from the flux trapped inside the superconductor. Conversely, the flux density can often be enhanced on the face opposite to the ferromagnet (superconductor side); it is suggested that the flux density increase due to the ferromagnet is more significant when combined to a rather thin superconducting pellet. In all the studied cases, the presence of the ferromagnet was found to increase both the average trapped flux inside the superconductor and the magnetic moment of the whole SC/FM structure (including the ferromagnet). The ferromagnet ability to divert magnetic flux lines depends on whether it is partially or fully saturated. This saturation is found to be governed in the remanent state by the ferromagnet thickness d, its saturation magnetization M_sat and the flux produced by the superconductor (proportional to its critical current density J_c). The amount of diverted / shielded flux does not change once the ferromagnet is fully saturated and the effect of the ferromagnet becomes relatively less important as the generated flux increases. Hybrid structures are therefore relevant even when the trapped flux density exceeds the typical saturation magnetization of ferromagnetic materials (≈ 2 T). For a given critical current the higher the saturation magnetization and/or the thicker the ferromagnetic material, the larger the shielding effects on the ferromagnet side and the higher the trapped field on the superconductor face for the investigated sample. For a ferromagnetic disc with the same diameter a as the superconductor, the most suitable ferromagnet thickness d^* can be roughly estimated by a simplified analytical expression d^*≈(J_c0 a^2 )⁄( 6M_sat ), below which nearly full saturation of the FM occurs and above which weak thickness dependence is observed. The magnitude of the supercurrent is an important parameter but its particular J_c (B) dependence is found not to be a crucial parameter affecting the remanent state properties of the modelled hybrid configurations. In addition, the time relaxation of the trapped magnetization was found not to be influenced by the presence of the ferromagnet, within measurement uncertainties. The ferromagnet also influences the magnetic flux density when the assembly is subjected to an external magnetic field. The penetration of the magnetic flux inside the superconductor is delayed in the vicinity of the ferromagnet. The hysteresis loops of the flux density averaged on the superconductor volume show a combination of diamagnetic and ferromagnetic behaviour for SC/FM structures. It appears to be the simple superimposition of the hysteresis cycles of the superconductor and the ferromagnet at high applied field (i.e. exceeding the apparent saturation of the ferromagnet). This simple “addition” rule can be used to effectively predict the magnetic behaviour of larger or more complex hybrid structures and to modulate the magnetic flux density. As in the remanent sate, a thicker ferromagnet has a more significant effect on the whole hysteresis loop of the superconductor, but this effect varies less than proportionally to the increase in the ferromagnet volume. For a given volume of ferromagnetic material, the shape of an unsaturated ferromagnet is not of prime importance provided that the ferromagnet covers the entire surface of the superconductor. A succession of holes and ferromagnetic sections could be used to modulate the flux density. A similar volume of ferromagnetic material was shown to have more influence on the average remanent volume flux density if it is split on both faces of the superconductor to form a FM/SC/FM structure instead of a SC/FM structure. Two additional advantages of ferromagnets were identified in this work. First, the ferromagnet was shown to be beneficial in improving the field gradient – and therefore the magnetic levitation force – outside the superconductor. Second, the addition of the ferromagnetic disc on one side of the superconductor reduces the collapse of the trapped flux density when subjected to several cycles of magnetic field applied perpendicularly to its remanent magnetization (parallel to the c-axis), i.e. in the so-called “crossed-field configuration”. [less ▲]

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

Doctoral thesis (2015)

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

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

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See detailCondições Semióticas da Repetição
Lindenberg Lemos, Carolina ULg

Doctoral thesis (2015)

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

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

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See detailLattice dynamics in antimony and tellurium based phase-change materials
Simon, Ronnie Ernst ULg

Doctoral thesis (2015)

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See detailL'art des jardins dans les Pays-Bas méridionaux et la principauté de Liège (1761-1827) : évolution des formes et passion botanique sous l'influence des Lumières
De Harlez De Deulin, Nathalie ULg

Doctoral thesis (2015)

The shift from regular to irregular layouts was a major break in the European history of gardens. This mutation of a long-standing geometrical tradition was initiated in England in the 1720s. In the ... [more ▼]

The shift from regular to irregular layouts was a major break in the European history of gardens. This mutation of a long-standing geometrical tradition was initiated in England in the 1720s. In the southern Low Countries and the Principality of Liège, this evolution of forms can be observed from 1761 on, and had a global impact over the four last decades of the 18th century. Under influence of the Enlightenment, the Grand Tour, and the discovery of picturesque English gardens, the attraction for irregularity led to a profound redefinition of composition and layout of gardens. This evolution had important philosophical, scientific, and technical dimensions. The analysis of this prolific production necessitated a confrontation with archives and evidence, but also a methodological discussion in order to outline the major episodes of this history, to identify the evolutions of the layout of gardens, and the favored modes of expression (“Goût mélangé”, English gardens, Anglo-Chinese gardens) as they were apprehended through the gaze of contemporaries who designed, commissioned, or developed gardens, as well as artists, writers, scientists, or simple visitors. A corpus of c. 600 written, iconographic, and archival documents necessitated a transversal approach, that illustrates all the complexity and originality of these gardens. These can be understood as cultural references of the Enlightenment, that are articulated with the development of landscape design and the emergence of professional landscape-designers in the early 19th century. A critical approach to the evidence reveals the extraordinary enthusiasm of contemporaries for garden art, their keen interest in exoticism, and a genuine passion for the introduction of foreign plants, that came from increasingly far away. This led to the development of botanical collections and the multiplication of horticultural infrastructures. A comparative analysis of garden plans, projects and views, of accounts of perambulations and visits, as well as inventories of mortuary houses and remains of gardens, contributes to develop a new perspective on the programs developed in the layout of gardens, as well as the nature of their constituent parts, i.e. buildings, infrastructures, and plants. The study of emblematic gardens and the examination of the work of several designers among the most creatives led to the development of thematic analyses, that highlight the involvement of many actors with Freemasonry, the overall domination of architects over the conception of gardens, and the emergence of commissioning owners as active figures in the organization of their property. Their new approach to property encompassed residence, garden, and landscape. It contributed to the social distinction of the owners and the development of their artistic and cultural values. [less ▲]

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See detailLa figurine cisanthrope - Humanité liminale et contagion affective dans le cinéma d'animation
Collignon, Stéphane ULg

Doctoral thesis (2015)

This thesis aims at answering an apparently simple question: How come "cartoony" characters always seem to be able to trigger better affective responses than more realistic ones (therefore avoiding the ... [more ▼]

This thesis aims at answering an apparently simple question: How come "cartoony" characters always seem to be able to trigger better affective responses than more realistic ones (therefore avoiding the uncanny valley). By linking classical animated cartoons to their print cartoon ancestors, the author is able to call upon the array of studies on caricature perception to build a new understanding of animated character design, summed up into a type of character called cisanthropic figurine. [less ▲]

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See detailLa cécidomyie équestre, Haplodiplosis marginata (von Roser) : appréhension des risques et développement d'outils pour une gestion intégrée
Censier, Florence ULg

Doctoral thesis (2015)

The saddle gall midge, Haplodiplosis marginata (von Roser) (Diptera: Cecidomyiidae), is an inconspicuous pest that has caused severe damage in cereals in recent years, not only in Belgium but also in ... [more ▼]

The saddle gall midge, Haplodiplosis marginata (von Roser) (Diptera: Cecidomyiidae), is an inconspicuous pest that has caused severe damage in cereals in recent years, not only in Belgium but also in other European countries. This thesis first describes the work conducted to assess the risk posed to cereal crops by this insect. Experiments were carried out in greenhouses in order to characterize the host plant-pest interaction and to assess the sensitivity of several cereals varieties to H. marginata. Trials were then conducted in winter wheat fields in order to assess the harmfulness of the pest by measuring the impact of H. marginata galls on yield and to establishe the approach needed to ensure the effectiveness of phytosanitary treatments. With the aim of developing a tool to monitor flights accurately and to determine when to apply curative measures in the case of severe infestations, research of the H. marginata sex pheromone was undertaken by analysing the volatile organic compound emitted by young virgin adults. Several esters produced only by females were detected and identified, including non-2-yl butanoate, the most dominant molecule emitted. Field tests using prototype dispensers demonstrated the attractiveness of this molecule and confirmed that it was the major sex pheromone component of H. marginata. Slow-release dispensers were then prepared from rubber septa loaded with 5 mg or 10 mg of non-2-yl butanoate. Their release rates were estimated under laboratory conditions for a month, before testing them in the field using white delta traps with sticky inserts. The capture efficiency of the traps was assessed in terms of pheromone loading and use duration (lures were kept in the traps throughout the whole season or renewed every third week) in order to determine the most appropriate lure type and monitoring requirements for H. marginata populations. [less ▲]

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See detailSelenium status in cattle herds in Wallonia and effects of a fattening diet with selenium-enriched cereals on animal performance, on chemical composition and on meat quality in Belgian Blue bulls
Mehdi, Youcef ULg

Doctoral thesis (2015)

Selenium (Se 34_79) is a trace element of importance to the body. Its importance is related to its anti-oxidative capacity, and its involvement in the synthesis of thyroid hormones and selenoproteins ... [more ▼]

Selenium (Se 34_79) is a trace element of importance to the body. Its importance is related to its anti-oxidative capacity, and its involvement in the synthesis of thyroid hormones and selenoproteins. These selenoproteins and some selenium compounds such as methylselenol are involved in reducing the accumulation of free radicals and in the prevention of myopathies and some cancers. The presence of selenium in the body ensures correct functioning of the immune system. Studies showed that selenium deficiency reduces phagocytic capacity and cell mobility. The presence of selenium in the body also ensures healthy reproduction, in terms of spermatogenesis or in the prevention of mastitis and metritis in cows. There is, subsequently a reduction of negative economic impact of these anomalies in the farms. The recommended daily intake of selenium in animals varies according to species and the animal type from 100 to 300 µg/kg dry matter (DM). Nutritional selenium requirements in cattle are often not met by locally produced feedstuffs, owing to the very small selenium content. This is mainly due to the types of soils naturally poor in selenium, but also to the low selenium accumulating capacity of forages alone with the pedoclimatic conditions (soil pH and precipitations) which limit the selenium bioavailability in the soil. Consequently, the selenium intake in humans is not met. In Belgium, for example, the average daily intake of selenium is estimated to be between 28 and 60 µg, while the recommended amount by the High Council of Health is 60 µg / day for women and 70 µg / day for men. An additional selenium supplement in feedstuffs for beef and dairy cattle may help to maintain the selenium status, improve cattle health and finally to increase the selenium content in meat and milk. Subsequently, this will help to ensure an adequate selenium supply in humans. The aim of this present research was to assess the effects of a dietary selenium supply in fattening Belgian Blue bulls. The strategy consisted in incorporating in the bulls feed cereals produced with selenium-enriched fertilizers. Instead of the usual addition of sodium selenite and selenized yeasts used as selenium supply, the present enrichment technique follows the soil-plant-animal axis. It aimed primarily to ensure an adequate dietary selenium intake in Belgian Blue bulls, with as effects, a bio fortification of meat in selenium. The first part of the present work is a review paper entitled “Selenium in the Environment, Metabolism and Involvement in Body Functions”. It reports key findings on selenium, its physicochemical properties, its production and presence in the environment, its implication into the organism and effects of its deficiencies in humans and animals. This first study is followed by a second review paper entitled “Selenium in cattle”. It focuses on the effects of selenium deficiency and supplementation in the bovine species (bull, cow and calf). It is thus a synthesis of current understanding about on selenium in cattle. The aim was to review the effects of selenium deficiency and selenium supplementation on growth, on reproduction and on the beef products mainly meat and milk. The experimental part of this work began with an epidemiological study on selenium status in cattle herds in Wallonia. The objective of this study was to provide an overview on/of the blood selenium content in/of cattle in Wallonia. The selenium content was evaluated through the measurement of glutathione peroxidase activity in red blood cells. Data were available on 114 heifers and 184 cows (82 dairy cows and 102 beef cows) distributed over 66 farms in Wallonia. Four agricultural regions were involved in this study namely, the Limoneuse region, the Condroz, the Ardennes and the Famenne region. It appeared from the study that 87% of cattle herds in Wallonia presented a marginal or severe deficiency in selenium (<80 µg/L). Only 13% of animals had adequate selenium status (> 81 µg/L). The lowest selenium status was recorded in the Ardennes region. The average selenium contents recorded in the Ardennes were 34 µg / L in heifers, 44 µg / L in dairy cows and 32 µg /L in beef cows. Compared to other agricultural regions, the highest contents of selenium in dairy cows (64 µg /L) and a beef cow (55 µg/L) were recorded respectively in the Limoneuse Region and in Famenne. The selenium content in beef herds was lower compared to dairy herds (35 vs 56 µg / L, p <0.01). The selenium deficiency could be a determining factor in increasing of frequency of mastitis, metritis and myopathies. Selenium deficiency can be prevented either by selenium dietary supplementation and selenium injections in deficient animals. The use of selenized fertilizers and selenium-enriched ingredients or feedstuffs with high selenium content has been shown to help correct deficiencies observed in cattle. Similar effects can be expected all over Belgium and in countries in which selenium deficiencies have been reported. “Meat composition and quality of young growing Belgian Blue bulls offered a fattening diet with selenium enriched cereals” was the second research of the experimental part of the present work. It consisted to feed growing fattening bulls diet in which spelt and barley were enriched in selenium. The selenium enrichment of the two cereals was obtained by a particular culture technique. The cereals were grown with fertilizers containing sodium selenate. An amount of 4 g of selenate was applied per hectare. These cereals were introduced in the experimental feedstuffs used in the feeding of the fattening Belgian Blue bulls. The objective of this trial was to evaluate the effects of the use of these selenium fortified cereals on growth performance, quality and chemical composition of meat. A total of 23 young bulls were used. Twelve bulls received a control diet containing selenium at a rate of 58 µg/kg DM and the 11 others received a diet with selenium at 173 µg/kg DM. The results of this experiment indicated that the selenium enrichment of diet had no significant effect on growth performance. The final live weight gain, average daily gain (ADG) and feed conversion ratio were similar in both groups. Slaughter data were not influenced either by the addition of selenium. Since the carcass weight, yield, shrinkage and the percentage of muscles were similar in both groups. The meat quality measured by the pH drop, by color, by oxidative rancidity and by water loss was not affected by the addition of selenium. Similarly, in terms of chemical composition of meat, dry matter and protein content were not significantly affected. However, significant effects were recorded on the ether extract content (2.1 vs 1.7 % DM, p <0.05) of meat. The selenium content increased significantly in the plasma (31 vs. 66 ng/ml, p <0.001) and in the Longissimus thoracis muscle (177 vs. 477 ng/g DM, p<0.001). A high increase of selenium was also recorded in the organs: liver (474 vs. 1126 ng/g DM), kidneys (4956 vs. 5655 ng/g DM) and testes (2070 vs. 2309 ng/g DM ). The use of selenium-enriched cereals appeared to be a good method of supplementing selenium in fattening bulls. Such a method of supplementation did not alter the physical and chemical qualities of the meat and induced a decrease in the fat content of meat. Furthermore, there were increased contents of selenium in the blood and organs of the bulls. The consumption of meat produced under such conditions would help to provide between 30 and 57% of daily selenium requirements. In our knowledge, this method of supplementing selenium in cattle, in particular in Belgian Blue bulls, and selenium bio-fortification of meat, is original. The application of the technique used in the present work seems to be useful in helping to reduce selenium deficiency in regions and countries in which they are observed. A similar trial with different levels of selenium in the diet should be designed in order to test a "dose" effect on the same parameters as studied in this work. It would also be interesting in future to conduct a comparative study between the type of supplementation developed in this work and an addition of mineral and/or organic selenium in order to evaluate the "type and source of selenium" effects on the studied parameters. Finally, a technical and economical study should be undertaken to assess the cost of these selenium supplementation types. [less ▲]

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See detailCaractérisation et étude des cellules endocrines du tractus gastro-intestinal chez le zebrafish (Danio rerio)
Pirson, Justine ULg

Doctoral thesis (2015)

Les cellules endocrines du tube digestif comprennent les cellules pancréatiques regroupées en îlots de Langerhans et les cellules entéroendocrines dispersées tout le long de l’épithélium du tube digestif ... [more ▼]

Les cellules endocrines du tube digestif comprennent les cellules pancréatiques regroupées en îlots de Langerhans et les cellules entéroendocrines dispersées tout le long de l’épithélium du tube digestif. Bien que ces deux populations de cellules endocrines soient localisées dans deux organes différents, elles présentent des similarités au niveau des hormones qui y sont exprimées et des facteurs de transcription impliqués dans leur différenciation. En effet, chez la souris, les hormones telles que le pro-glucagon, la somatostatine, la ghréline et le polypeptide pancréatique (PP) sont exprimées au niveau des cellules pancréatiques et entéroendocrines. Il en est de même pour les facteurs de transcription Ngn3, Pdx1, Nkx2.2, NeuroD1, Arx, Pax6 et Pax4 qui sont à la fois exprimés et impliqués lors du développement des cellules pancréatiques et entéroendocrines. Un dysfonctionnement au niveau de ces cellules conduit à de graves maladies. Dans la recherche de nouveaux traitements pour les patients diabétiques, une des investigations prometteuses porte sur la transdifférenciation des cellules entéroendocrines en cellules productrices d’insuline. Dès lors, une compréhension approfondie des similarités et des divergences entre ces deux types cellulaires aussi bien d’un point de vue moléculaire que fonctionnel est primordiale. L’objectif de cette thèse a donc été de caractériser les cellules endocrines intestinales et pancréatiques, et d’amorcer l’étude des mécanismes moléculaires contrôlant la formation des cellules entéroendocrines et d’ensuite les comparer au niveau pancréatique. Au cours de ce travail, nous avons réalisé une caractérisation approfondie encore jamais réalisée chez le zebrafish, des cellules hormonales présentes dans l’intestin. Nous avons montré que 15 hormones murines et humaines sur 19 ont été retrouvées comme étant exprimées au niveau des cellules entéroendocrines chez le zebrafish. Ces hormones débutent leur expression à des moments distincts et sont présentes différemment le long du tube digestif. Au début de ce travail, l’expression de seuls certains facteurs de transcription, connus comme étant exprimés dans les cellules endocrines pancréatiques chez le zebrafish, avait aussi été retrouvée dans les cellules entéroendocrines. Suggérant une relation étroite entre ces deux types cellulaires au niveau de leur cascade régulatrice, nous avons donc caractérisé le moment d’apparition et la localisation intestinale pour l’ensemble des facteurs de transcription pancréatiques connus chez le zebrafish. Nous avons identifié 13 facteurs de transcription pancréatiques comme étant exprimés dans l’intestin sur les 18 connus. Parmi ces 13 facteurs, nous avons étudié le facteur isl1 à la fois dans le tube gastro-intestinal et le pancréas. Dans le tube digestif, le facteur isl1 est exclusivement présent dans la lignée entéroendocrine et est exprimé dans un sous-groupe de cellules entéroendocrines matures. Ce facteur agit lors des dernières étapes de la cascade régulatrice de différenciation. Au niveau pancréatique, isl1 est requis lors de la première et de la deuxième vague de différenciation pour une sous-population des cellules hormonales pancréatiques. L’étude du mutant isl1-/- a montré que la fonction principale du facteur de transcription isl1 entre les cellules endocrines pancréatiques et intestinales semble identique, c’est-à-dire que isl1 est nécessaire pour la différenciation terminale d’une sous-population de ces cellules. Cependant, un phénomène de compensation semble se mettre en place dans le mutant isl1-/- au niveau pancréatique. Cette étude a été complétée par une analyse transcriptomique réalisée par RNA-seq afin d’identifier les cibles de ce facteur dans les deux tissus. [less ▲]

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Posho Ndola, Boniface ULg

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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See detailDiagnosis and clinical interest of asthma inflammatory phenotypes

Doctoral thesis (2014)

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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See detailLes généralistes, la prévention et la promotion de la santé. Etat des lieux, attitudes actuelles et voies d’avenir
Vanmeerbeek, Marc ULg

Doctoral thesis (2014)

The aim of this work was to identify ways to apply preventive health services provided by general practitioners to health improvement, rather than case-by-case improvements of biomedical markers. Health ... [more ▼]

The aim of this work was to identify ways to apply preventive health services provided by general practitioners to health improvement, rather than case-by-case improvements of biomedical markers. Health was considered within its bio-psycho-social definition, and equity in health had to be maintained or improved in this process. Research questions: • What are general practitioners (GPs)’ representations of their role and actions in the Belgian preventive framework? (Chapter 2); • What factors can predict GPs’ involvement to a greater or lesser degree in this topic? (Chapter 3); • What are the published operating models about preventive health care and health promotion in primary care that can be used to formulate working hypotheses for the improvement of preventive clinical practice? (Chapter 4). • How to improve the connection between preventive health services, health promotion and the curative approach? (Chapter 5). Four studies are presented that illustrate the topic, as they were published (or under publication). Among the definitions of health, the weight of the structural determinants and the socio-economic context on health levels was stressed, while the weight of the health systems was gradually reduced to a lesser role. But patient education is still expected to help control the individual determinants of health. Primary care and general practice are adequately fit to a tailored approach of large populations. However, the physicians’ vocational training does not address integration of health promotion and curative practice. Meeting field GPs through individual semi-structured interviews allowed for a dialog that explored various aspects of the preventive health services delivery. Predisposing factors closely linked to the physicians’ personality appeared to be determinants. Organisational limitations and difficulties, and almost non-existent collective visions of the practice population were highlighted. To understand what shapes the behaviour of GPs in preventive healthcare delivery beyond statements, an attitude scale was devised. The analysis allowed the statements to be sorted into a four-factor model consisting of performance appraisal, guideline adherence, patient-centeredness & collaboration, and power sharing. The GPs’ attitudes towards preventative service delivery increased with multidisciplinary practice and decreased with seniority in the profession. A narrative literature review retrieved twelve models that address preventive health care and health promotion in primary care; these models helped formulate working hypotheses for the improvement the current situation. The models progressively integrated elements from the health promotion charters of the World Health Organisation and from the Commission on Social Determinants of Health. The following elements valued by health promotion could be integrated to preventive healthcare: empowerment of citizens, addressing community environment; increased involvement in local health professionals’ networks; and the integration of individual and collective approaches within the same health care facilities to simultaneously address individual customisation, efficiency and equity objectives. There was little room for patients in elaborating the models. Do GPs have the opportunity to develop the partnerships that are required to move to health promotion as proposed by these models? The trend toward quality assurance systems among health systems can contribute to the setting of structures and operating modes that are necessary. The quality cycle could be one of the tools used for that purpose. The quality criteria of primary care lead the way to a framework for integrating preventive health care and health promotion. • Comprehensive care addresses the bio-psycho-social environment of patients, considering patients as partners during the health care process. • Continuity of care challenges the managing of clinical data between members of a care team, thereby enhancing quality of care, patient safety and equity. • Integrated care involving caregivers and health promotion professionals will require adaptation of job description reference lists. The challenge created by these three quality criteria entails changes in GPs vocational training and necessitates a new definition of their specific tasks and skills. Such a challenge requires collaborative teamwork of the five members of Boelen’s “partnership pentagon”. The social accountability of medical schools should be fostered. [less ▲]

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Liady, Mouhamadou Nourou Dine ULg

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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

Doctoral thesis (2014)

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

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

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