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See detailAltérations fonctionnelles des cellules dendritiques dans la cancérisation du col utérin
Demoulin, Stéphanie ULg

Doctoral thesis (2014)

Le cancer du col utérin (SCC) est presque universellement associé à une infection par des papillomavirus à haut risque (HR-HPV) et est une des principales causes de décès par cancer chez les femmes à ... [more ▼]

Le cancer du col utérin (SCC) est presque universellement associé à une infection par des papillomavirus à haut risque (HR-HPV) et est une des principales causes de décès par cancer chez les femmes à travers le monde. Actuellement, deux vaccins empêchant l'infection par des HR-HPV spécifiques sont disponibles, cependant, ils n'ont pas d'efficacité thérapeutique et il a été estimé qu'il n'y aura pas de baisse mesurable des cancers associés à HPV avant 2040. Même si l'infection par les HR-HPV est nécessaire à la carcinogenèse du col utérin, elle n'est pas suffisante pour le développement du cancer puisque seule une minorité des cas progresseront vers une tumeur. En effet, d’autres facteurs, liés à l’hôte ou environnementaux, qui agissent après l’infection peuvent augmenter le risque de développement cancéreux. Récemment, il a été proposé que les cellules épithéliales et/ou inflammatoires pourraient créer un environnement immunosuppresseur facilitant la transformation maligne en altérant l'immunité antitumorale. Etant donné que plusieurs études ont montré que le microenvironnement tumoral pouvait altérer la fonction des cellules dendritiques plasmacytoïdes (pDC) et conventionnelles (cDC) et les rendre tolérogènes, nous avons concentré notre attention sur ces cellules et sur leur rôle potentiel dans la cancérisation du col utérin. Dans la première partie de ce travail, nous nous sommes concentrés sur l'implication des pDC dans la cancérisation du col utérin. Nous avons d'abord montré que ces cellules sont recrutées au cours de la séquence "métaplasie-dysplasie-cancer" du col de l’utérus suite à l’augmentation de l'expression de la chémérine dans ces lésions. Etant donné que les pDC représentent un population cellulaire rare dans le sang périphérique, nous avons développé une nouvelle méthode afin de générer un grand nombre de pDC à partir d'un nombre limité de cellules progénitrices CD34+ isolées de sang de cordon ombilical. Notre but était de fournir un outil permettant de définir si la fonction de ces cellules peut être influencée par le microenvironnement tumoral. Les pDC générées in vitro présentent la morphologie, les caractéristiques phénotypiques et fonctionnelles des pDC se trouvant dans le sang périphérique. Les pDC générées in vitro ont été exposées aux molécules sécrétées dans le microenvironnement du cancer du col utérin grâce à un système de coculture. Ces pDC présentent un profil de maturation altéré, une diminution de sécrétion en IFN-α, une cytokine ayant un rôle antiviral et antitumoral. De plus, ces pDC sont capables d’induire la différenciation des lymphocytes T CD4+ naïfs en cellules T régulatrices (Treg) grâce à l’expression d’ICOSL. Les cellules Treg et les pDC forment des clusters autour des cellules cancéreuses, ce qui facilite leurs interactions. Nous avons identifié HMGB1 comme étant la molécule impliquée dans la modification du phénotype et de la fonction des pDC exposées au microenvironnement du col utérin. En parallèle, nous avons démontré que les cDC différenciées en présence de lignées de SCC du col utérin acquièrent un phénotype semi-mature et une activité fonctionnelle défectueuse, associée à une augmentation de leur sécrétion d'IL-10, une cytokine immunosuppressive. En outre, les cDC présentent également une fonction tolérogène associée à leur expression d’ILT3. L’inhibition de la voie de signalisation RANK/RANKL a permis de limiter l’effet des lignées de SCC sur les cDC. Ainsi, le cancer du col de l’utérus exploite activement la plasticité des pDC et des cDC afin de promouvoir sa progression. Des traitements ciblant HMGB1 et RANKL pourraient être utilisés afin de restaurer les activités anti-tumorales des cellules dendritiques et, par conséquent, de surmonter la tolérance immunitaire associée au microenvironnement du cancer du col utérin. [less ▲]

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See detailEtude du rôle des sites de N-glycosylation dans la pathogenèse induite par le virus de la leucémie bovine
De Brogniez, Alix ULg

Doctoral thesis (2014)

Le virus de la leucémie bovine (BLV) est un deltarétrovirus responsable d’une maladie lymphoproliférative chez le bovin. Cette maladie, appelée leucose bovine enzootique, est responsable de pertes ... [more ▼]

Le virus de la leucémie bovine (BLV) est un deltarétrovirus responsable d’une maladie lymphoproliférative chez le bovin. Cette maladie, appelée leucose bovine enzootique, est responsable de pertes économiques importantes dans l’industrie laitière et viandeuse de nombreux pays dont notamment les Etats-Unis, l’Argentine et le Brésil. Ce rétrovirus infecte les lymphocytes B à l’aide de ses glycoprotéines virales SU et TM qui fusionnent avec la membrane cellulaire. Bien que de nombreuses études se soient penchées sur la caractérisation de la propagation virale, les composants cellulaires et viraux impliqués dans le contrôle de ce mécanisme ne sont toujours pas élucidés. Mon projet de thèse s’est donc attaché à la compréhension du rôle joué par les 8 sites potentiels de glycosylation présents sur la protéine SU du BLV. Chaque site du gène a été muté individuellement par mutagenèse dirigée. L’expression, la localisation, la capacité de fusion cellulaire et la stabilité protéique ont d’abord été étudiées en culture. Des provirus mutés ont ensuite été inoculés à des moutons afin d’évaluer leur potentiel infectieux et de suivre l’évolution de la pathogenèse induite. Nos études ont permis de mettre en évidence un mécanisme de glycosylation qui limite la réplication virale et ralentit la pathogenèse en faveur de la persistance virale. [less ▲]

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See detailTheoretical studies of PbTiO3 and SrTiO3 under uniaxial mechanical constraints combining first-principles calculations and phenomenological Landau theory
Sharma, Henu ULg

Doctoral thesis (2014)

In the present thesis we present theoretical studies of perovskite compounds under uniaxial mechanical constraints combining first-principles DFT calculations approach and phenomenological Landau theory ... [more ▼]

In the present thesis we present theoretical studies of perovskite compounds under uniaxial mechanical constraints combining first-principles DFT calculations approach and phenomenological Landau theory. ABO$_3$ perovskites form a very important class of functional materials that can exhibit a broad range of properties (e.g., superconductivity, magnetism, ferroelectricity, multiferroism, metal-insulator transitions\ldots) within small distortions of the same simple prototype cubic structure. Though these compounds have been extensively studied both experimentally and computationally, there are still unresolved issues regarding the effect of pressure. In recent years, strain engineering has reported to be an original approach to tune the ferroelectric properties of perovskite ABO$_3$ compounds. While the effect of epitaxial biaxial strain and hydrostatic strain is rather well understood in this class of materials, very little is yet known regarding the effect of uniaxial mechanical constraints. Our study is motivated by the little existing understanding of the effect of uniaxial strain and stress, that has been up to now almost totally neglected. Two prototype compounds are studied in detail: PbTiO$_3$ and SrTiO$_3$. After a general introduction on ABO$_3$ compounds and calculations techniques (ab initio and phenomenological Landau model), we studied the effect of mechanical constraints in these compounds in our thesis. PbTiO$_3$ is a prototypical ferroelectric compound and also one of the parent components of the Pb(Zr,Ti)O$_3$ solid solution (PZT), which is the most widely used piezoelectrics. For PbTiO$_3$, we have shown that irrespectively of the uniaxial mechanical constraint applied, the system keeps a purely ferroelectric ground-state, with the polarization aligned either along the constraint direction ($FE_z$ phase) or along one of the pseudo-cubic axis perpendicular to it ($FE_x$ phase). This contrasts with the case of isotropic or biaxial mechanical constraints for which novel phases combining ferroelectric and antiferrodistortive motions have been previously reported. Under uniaxial strain, PbTiO$_3$ switches from a $FE_x$ ground state under compressive strain to $FE_z$ ground-state under tensile strain, beyond a critical strain $\eta_{zz}^c \approx +1$\%. Under uniaxial stress, PbTiO$_3$ exhibits either a $FE_x$ ground state under compression ($\sigma_{zz} < 0$) or a $FE_z$ ground state under tension ($\sigma_{zz} > 0$). Here, however, an abrupt jump of the structural parameters is also predicted under both compressive and tensile stresses at critical values $\sigma_{zz} \approx$ $+2$ GPa and $- 8$ GPa. This behavior appears similar to that predicted under negative isotropic pressure and might reveal practically useful to enhance the piezoelectric response in nanodevices. The second compound of interest is SrTiO$_3$. It has been widely studied in the past decades due to its unusual properties at low temperature. In this work, we have extended our previous investigations on PbTiO$_3$ by exploring theoretically the pressure effects on perovskite SrTiO$_3$ combining the first-principles calculations and a phenomenological Landau model. We have discussed the evolution of phonon frequencies of SrTiO$_3$ with the three isotropic, uniaxial and biaxial strains using first-principles calculations. We also reproduce the previous work done in SrTiO$_3$ with epitaxial strain and hydrostatic strain. Finally, we have calculated the phase diagram of SrTiO$_3$ under uniaxial strain, as obtained from Landau theory and discussed how it compares with the first-principles calculations. [less ▲]

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See detailBehavioral ecology and commensal long-tailed macaque (Macaca fascicularis) populations in Bali, Indonesia: impact of anthropic factors
Brotcorne, Fany ULg

Doctoral thesis (2014)

Coexistence between humans and wildlife is one of the major challenge to biodiversity conservation in the onset of this new millennium. In addition to the development of protected areas providing refuges ... [more ▼]

Coexistence between humans and wildlife is one of the major challenge to biodiversity conservation in the onset of this new millennium. In addition to the development of protected areas providing refuges for wildlife populations, another option relies on the sharing of space, i.e., tolerating wildlife living alongside human populations in non-protected interface zones. During the last century, massive human encroachment into wildlife natural habitat has led to an increasing number of worldwide interface zones and a consecutive intensification of the human-wildlife conflict which is likely to escalate further as human populations rapidly expand. However, conflict does not account for all the scenarios since diverse forms of interaction between humans and wildlife exist. The human-nonhuman primate commensalism is one of these possible interspecies associations. Commensal (or synanthropic) primates are free-ranging populations ecologically associated with humans in anthropogenic habitats and taking advantage of human food, waste or crops to supplement their diet. In Bali, Indonesia, humans and long-tailed macaques (Macaca fascicularis) already have a long history of coexistence. The forest-agricultural matrix landscape of the island and the numerous religious Hindu temples provide habitat patches for macaques sometimes living in very close proximity to humans. The opportunistic style of this species enables it to exploit numerous habitat types. However little is known about the ways anthropic factors impact its behavioral ecology. Our intention was to conduct a comparative study which would investigate whether anthropic factors were potential drivers of the behavioral ecology and population dynamics of Balinese macaques. During a two-year period in the field (between 2009 and 2013), using a protocol including three populations of Balinese macaques made of ten social groups, we documented variations in the activity, dietary, ranging and demographic patterns between populations. We systematically investigated the anthropogenic influences (i.e. human food provisioning degree and habitat anthropization level) on those variations, and we questioned the biological significance of the responses in terms of costs and benefits. While daily following each social group of macaques, we collected spatial, behavioral and botanical data, and we further conducted bi-annual demographic census in order to estimate the status and demographic trends of the study groups. Finally, our interest was to link our results with applied concerns regarding the management of these populations interacting with humans, while taking into account the implications of these interactions from the human point of view. We found a remarkable eco-behavioral diversity between our studied populations. Human food was a central component of their ecology, macaques preferentially exploiting this resource when available while retaining their abilities to forage on natural resources. The inclination for human food was optimal for macaques as it maximized their energy intake while minimizing the time expended for food acquisition. Therefore, they adjusted their activity budget according to the proportions of human food consumed. The free time available from relaxed foraging constraints was invested into resting and social activities. Macaques were flexible in their movements, making them successful in exploiting natural forest areas as well as highly anthropogenic habitats. However, increased social tension was a cost that stemmed from high-density situations induced by excessive anthropization of their habitat. We showed that, although predation risk partially influenced the selection of sleeping trees, proximity to human settlements appeared to be the most influential factor in the essential process of sleeping site choice by long-tailed macaques living at the edge of the forest and anthropogenic zones. Demographic data provide essential information to assess the status of a population and the long-term impacts of human pressures. Overall, our three studied populations displayed good reproductive performances and positive growth rates, probably due to the human food consumed. Indeed, we showed that the human food abundance in tourist sites may have diminished the density-dependence mechanism on macaques’ birth rates, to eventually inflate the size of populations. When combined with a high level of habitat anthropization, these effects have led to high local densities and even overcrowded situations with associated costs regarding within and between-group social tension and epidemic risks. In this framework, we documented the demographic and social impacts of a Streptococcus outbreak which occurred in the Ubud population in 2012. The pre- and post-epidemic study showed that macaques modified their social dynamics following a significant mortality in certain groups. This study emphasized the role of pathogens in regulating primate populations living in zones of interface with humans. Our research also contributed to identify solutions regarding management of these populations increasingly interacting with humans in Bali. We notably provided preliminary evidence that vasectomy, as sterilization technique to control for overpopulation, had no negative side-effects on social and sexual behaviors of male macaques. Finally, we assessed the effect of a ten-year management regime at the Ubud Monkey Forest, using an ethnoprimatological approach. We showed that the aggressiveness of macaques towards visitors had been effectively reduced and the high tolerance of local people towards macaques was determined by economic and cultural benefits deriving from the macaque presence. However, we also identified men and adult or subadult male macaques as the most exposed groups to a potential risk of cross-species pathogen transmission given the frequency of close physical contact interactions at this site. [less ▲]

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See detailBilan de carbone d'une prairie pâturée en Région wallonne: effets du climat et de la gestion du pâturage
Jerome, Elisabeth ULg

Doctoral thesis (2014)

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – ... [more ▼]

As grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems (carbon dioxide – CO2, nitrous oxide – N2O, methane – CH4), this PhD investigates the C balance of an intensively managed grazed grassland in the temperate climate of southern Belgium. It analyses more particularly impact of climatic conditions and management practices on the C balance. The research site is a permanent grassland, covering 4.22 ha, intensively used for more than 50 years for Belgian Blue cattle grazing with the application of organic and inorganic fertilizers. Management practices but also climatic conditions are representative of livestock production systems developed in southern Belgium. Over a three years study period, soil C stock variations are determined indirectly by measuring the balance of C fluxes at the system boundaries. This approach not only takes into account CO2 and CH4 exchanged with the atmosphere but also organic C imports (manures, complementary feedings), exports (harvests, animal products) and C lost through leaching. CO2 fluxes are measured by eddy covariance while other C fluxes are estimated from data provided directly by the farmer, from punctual measurements and from aboveground herbage mass measurements. Considering only assimilation and respiration, the ecosystem behaves, on average, as a weak CO2 source, although the interannual variability is large. Interannual variability seems not to be significantly correlated with the main environmental drivers but rather influenced by fertilization management. Taking other C fluxes into account, the site appears as being at equilibrium. Management (organic fertilization), as well as climatic conditions that dictated them (complementary feeds), are the principal factors influencing the C balance. Finally, results show that management practices were the key control of the C flux variability at this grassland. Grazing impact on CO2 fluxes appears not explicitly at the seasonal and annual scale. It is therefore quantified by developing innovative eddy covariance data analyses and experiments. For that, indirect and direct grazing impacts are separated. Indirect impact results from biomass consumption, excretion deposits and soil compaction by cattle modifying CO2 exchanges. To quantify it, the variation during periods with fixed stocking rate of gross primary productivity at light saturation (GPPmax) and normalised dark respiration (Rd,10) is analysed. On average, GPPmax decreases during grazing periods and increases during non-grazing periods. This could respectively be explained by aboveground biomass reduction and re-growth. In addition, GPPmax variations are negatively correlated to grazing intensity (defined as the product of the stocking rate and the grazing duration). On the contrary, no significant evolution of Rd,10 is found during both grazing and non-grazing periods, probably due to a combination of opposing effects of grazing on the total ecosystem respiration components. Direct impact results from livestock CO2 emissions through respiration that adds to the total ecosystem respiration. It is emphasized through specific designed livestock confinement experiments. Net CO2 exchange is compared on successive days with similar climatic conditions, livestock being confined (≈ 26 livestock units ha-1), or not, in the main wind direction area of the eddy covariance set-up. Results obtained are corroborated by independent estimates based on the C ingested by cattle during confinement. Finally, the C balance analysis of this particular grazed grassland in southern Belgium reveals that, taking into account the climatic conditions observed and the management practices developed over the three study years, the site is C neutral. This means that GHG emissions linked to fertilization (N2O) and grazing (CH4) are not partly mitigated by soil C sequestration. However, we conclude that, management practices being the main factor controlling the C balance, strategies to enhance soil C sequestration exist. If those kinds of management practices are studied, a global approach, taking into consideration both the C fluxes and other GHG fluxes, would be required to see if they do not induce supplementary N2O and CH4 emissions. [less ▲]

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See detailModélisation et étude expérimentale du comportement de Saccharomyces cerevisiae (boulardii) lors de l'extrapolation du procédé à des bioréacteurs de volume industriel
Lejeune, Annick ULg

Doctoral thesis (2014)

L’extrapolation de la production d’un microorganisme est un problème complexe qui prend en compte de nombreux paramètres. En effet, les paramètres opératoires induisent des conditions environnementales ... [more ▼]

L’extrapolation de la production d’un microorganisme est un problème complexe qui prend en compte de nombreux paramètres. En effet, les paramètres opératoires induisent des conditions environnementales qui peuvent être dommageables pour les cellules se développant dans le réacteur. Il est donc important de prendre en compte le côté génie chimique pour comprendre quelles sont les conditions hydrodynamiques présentes dans le réacteur et ensuite s’attacher à étudier la réponse des cellules vis-à-vis de ces conditions. Ce travail se place dans le cas particulier de la production de biomasse de Saccharomyces cerevisiae (boulardii). Dans ce cas, le point critique est l’ajout de la solution concentrée de substrat dans le réacteur. L’utilisation de réacteurs scale-down a permis d’étudier différents cas de conditions hydrodynamiques défavorables, ainsi que leurs impacts sur différents paramètres. Dans un premier temps, l’étude des paramètres ségrégés (concentration en biomasse, en co-produits…) a montré, notamment, une diminution du rendement et une augmentation de la concentration en éthanol. Ensuite, l’étude s’est placée au niveau cellulaire avec l’utilisation de souches exprimant une protéine recombinante fluorescente et de marqueurs cellulaires fluorescents, couplée à la cytométrie en flux. Ces techniques ont permis de mettre en évidence la présence de différentes sous-populations cellulaires, ainsi que l’apparition du phénomène de résistance cellulaire aux stress lors de la production en réacteurs scale-down. L’importance du choix de la méthode de traitement des données cytométriques a également été débattue. Ce travail a abordé différents domaines pour tenter de mieux comprendre la réponse cellulaire aux fluctuations des conditions environnementales ressenties par Saccharomyces cerevisiae (boulardii) lors de productions en réacteurs mimant les conditions hydrodynamiques des réacteurs de grands volumes. [less ▲]

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See detailLes dynamiques socio-économiques autour de l'Aire Marine Protégée Communautaire de Bamboung (Delta du Saloum, Sénégal): entre conservation et développement territorial
Gaye, Ndickou ULg

Doctoral thesis (2014)

The problem of the marine protected areas (MPA) in Senegal raises the question of how to balance socioeconomic dynamics and preservation. Since 2004, the network of MPA has been implemented along the ... [more ▼]

The problem of the marine protected areas (MPA) in Senegal raises the question of how to balance socioeconomic dynamics and preservation. Since 2004, the network of MPA has been implemented along the Senegalese coast where communities are strongly dependent on fishery resources. The thesis debates the difficult compatibility between preservation and development, it analyzes the emergent social and economic dynamics related to the creation of the community marine protected area of Bamboung, located in the Reserve of Biosphere of the delta of Saloum (Senegal). In the context of the implementation of this MPAC, the analysis studies the relative possibility of balancing preservation and development, as taken in a territorial approach. The resultas are based on surveys, led between 2010 and 2014, with fishermen, women collecting mollusks and transforming the fish, managers of the tourist sector, administrators of the MPAC, but also the local authorities. The results show how the development processes is related to endogenous and exogenous factors. The MPAC creates some growth due to the eco-touristic lodge “Keur Bamboung”, but also to the protection of the local resources. Some pre-existing dynamics are reinforced. All of this can contribute to the revelation and to the emergence of territorial resources of the MPAC. [less ▲]

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See detailPotentialités et limites de la gestion participative des Aires Marines Protégées : Le cas de Joal-Fadiouth, Sénégal
Sene, Claude ULg

Doctoral thesis (2014)

Increasingly, there is a strong international consensus on the fact that the participation of resident communities is one of the conditions for successful MPA (Marine Protected Area) governance. Thus ... [more ▼]

Increasingly, there is a strong international consensus on the fact that the participation of resident communities is one of the conditions for successful MPA (Marine Protected Area) governance. Thus, this thesis aims to contribute to this emerging debate on MPA governance through reflections about the experience of a conservation project implemented by an international NGO (WWF WMPAO) in collaboration with the State and the local populations in Joal-Fadiouth, with a view to identify the catalysts social factors. The results show that the objectives of the MPA project are not purely local; they are strongly influenced by a global standard as well as regional and national dynamics. Thus, the MPA is much more seen as a conservation tool, whith sanctuarization as philosophical and conceptual basis. This logic of action has led to a real discrepancy between the original objectives and the outcomes in daily practice in the field. The victory of "sanctuarization" on local development, despite discourses based on a constructive approach of the integration paradigm, gave rise to tensions and multiple repulsive reactions and claims in relation to local territorial rights. And in this respect, MPA is a “reserve with reservation”: it refers, on the one hand to a "sanctuarized" space and, on the other, to an increasingly challenged social acceptance in relationship to local territorial dynamics. This thesis has shown, through three case studies, the real potential of co-management regimes, which main catalyst factors are, but not limited to, the setting in the core of the process of actors with real decision-making powers and responsibilities, of information and awareness raising, of financial incentives to overcome the limitations, of integration of scientific expertise to endogenous knowledge, of support of the State and its decentralized services, and of the strengthening of local capacities ... Those co-management experiences offer real additional strategic options to the MPA tool in a global approach to fisheries governance and territorialized development. However, the results of the thesis show also the limits of participatory management induced by the projects (obligation of results short time-frame) through the "formatting of local institutions of governance" especially a Management Committee, which is struggling to meet its "excessive" responsibilities in light of its very limited resources. This committee has become a "local brokerage arena" which captures and capitalizes on co-management resources and means; which tends to move the real power towards "intermediary actors" who serve as populations/State interface or even "exploit" the administration officials. This thesis has also highlighted the paradox of the State that justifies and provides legitimacy to local co-management processes through legal institutionalization, but does not mobilize the legal, financial, human and logistical resources required to guarantee and secure the implementation of the agreements reached between the different actors. It has more of a posture of an organizing State than that of a State guarantor of management agreements. [less ▲]

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See detailLes pêcheurs migrants de Guet-Ndar (Saint-Louis du Sénégal) : analyse d’une territorialité diverse entre espaces de conflits et espaces de gestion
Seck, Aichetou ULg

Doctoral thesis (2014)

In Western Africa and more particularly in Senegal, the fishing represents an important sector. This situation involves diverse communities which, for several decades, work in the small- scale fisheries ... [more ▼]

In Western Africa and more particularly in Senegal, the fishing represents an important sector. This situation involves diverse communities which, for several decades, work in the small- scale fisheries and which print in the sea their own socio- spatial dynamics. Among these, fishermen’s community of Guet-Ndar, a district of the “langue de Barbarie” located on the big Senegalese coast constitute one of the most notable halieutic societies. Very early, this littoral population made the activity of fishing its exclusive speciality. So, those fishermen developed around the sea, under the regime of free access, quite new practices of which various forms of migration along African west coast. However, with the overexploitation of the fish stock, the Guet-Ndar migrant fishing is not without facing confrontations with autochthonous fishermen. This research aims on one hand, at understanding the evolving territoriality of the migrant fishermen of Guet-Ndar through the prism of conflicts which appear on their halieutic space, notably in Cayar and in Mauritania. On the other hand, it tries to see how these sea craftmen adapt and are collectively organizing and redefining their territories through local mobilizations and within the framework of regional policies. [less ▲]

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See detailEtude de la fibrose pulmonaire idiopathique canine: analyse du transcriptome, investigation des voies du TGF beta 1 et recherche de biomarqueurs
Krafft, Emilie ULg

Doctoral thesis (2014)

Canine idiopathic pulmonary fibrosis (cIPF) is a fibrotic disease of the pulmonary parenchyma, mainly seen in the West Highland white terrier. It is characterized by exercise intolerance and cough with a ... [more ▼]

Canine idiopathic pulmonary fibrosis (cIPF) is a fibrotic disease of the pulmonary parenchyma, mainly seen in the West Highland white terrier. It is characterized by exercise intolerance and cough with a progressive deterioration until death from respiratory insufficiency. Clinical, tomodensitometric and histological characteristics of cIPF have been described recently. However, this disease remains largely unknown and the clinicians are dealing with two major challenges: confirmation of the diagnosis, which requires many complementary exams, and absence of effective treatment. Identification of a targeted therapy is difficult without having a good understanding of the mechanisms leading to pulmonary parenchyma fibrosis. A similar disease, the idiopathic pulmonary fibrosis (IPF) is recognized in humans and cIPF might be interesting as a spontaneous model. This project in dogs was undertaken to answer, at least partly, to these challenges. The aims were to elucidate some mechanisms involved in cIPF pathogenesis and to identify biomarkers that could be used in the diagnosis process. The hypotheses were first that analysis of the transcriptome through microarray experiment would identify altered biological functions in cIPF, highlight specific molecules with an altered expression and identify potential biomarkers. Another hypothesis was the transforming growth factor beta 1 (TGFB1) pathways, considered central in the pathogenesis of IPF, would also be modified in cIPF. Finally, ET1, a known biomarker in human IPF, might also be an interesting biomarker in dogs. Gene expression analysis through microarray analysis, combined with the use of IPA, a data analysis program, identified altered biological functions in cIPF: cellular growth and proliferation, developmental processes, cellular movement, cell to cell signaling and interaction and antigen presentation. Some genes highlighted in the microarray experiment were then analyzed individually. Quantitative RT-PCR analysis confirmed an upregulation of the expression of CCL2, CCL7, CXCL14, IL8 and FAP (fibroblast activation protein) as well as a downregulation of the expression of PLUNC (palate, lung and nasal epithelium associated). We then complete the gene expression analysis with a search for potential biomarkers. Thirty-four potential biomarkers were identified with 32 biomarkers potentially measurable in blood (including CCL2, serum amyloid 1, IL8) and 2 biomarkers measurable only in the bronchoalveolar lavage fluid (BALF) (PLUNC and mesothelin). This approach was validated by measurement in serum of one of this biomarker: CCL2. CCL2 serum concentration was higher in affected WHWT compared to healthy WHWT and also higher in dogs with cIPF compared to dogs with chronic bronchitis (CB) or eosinophilic bronchopneumopathy (EBP). Based on serum CCL2 determination, cIPF was diagnosed with a sensibility of 92% and a specificity of 80%. We then studied TGFB1 and part of its storage, activation and signaling pathways. TGFB1 gene expression was not significantly different in the pulmonary parenchyma between affected and control dogs. However, in affected dogs, increased TGFB1 protein levels were seen by immunohistochemistry in fibrotic areas. High expression of bothTGFB1 type I receptor and phosphorylated Smad2/3, markers of an active intracellular TGFB1 signal, were seen in epithelial cells. No difference in expression for the storage proteins LTBP1 and LTBP2 was seen while expression of LTBP4 was significantly decreased in dogs with cIPF. Concerning the proteins involved in TGFB1 activation, gene expression was decreased for integrin subunit β8, increased for thrombospondin-1 and not modified for integrin subunit β6. Expression of Smad 7, involved in intracellular TGFB1 signal inhibition, was not modified. No difference for TGFB1 serum concentration was seen between WHWT with cIPF and healthy WHWT. A multivariate analysis performed on healthy dogs showed no age effect but a significant breed effect with higher levels in predisposed breeds. We evaluated part of the serotonin pathway, as one of its receptor (5HTR2B) was highlighted during the gene expression analysis. Serotonin has also been involved in the pathogenesis of human IPF and described to be of potential use as a biomarker in degenerative mitral valve disease in dogs. Expression of 2 serotonin receptors (5HTR2A and 5HTR2B), evaluated by quantitative RT-PCR in pulmonary tissue, was not different between dogs with cIPF and control dogs while expression of the serotonin transporter (5HTT) was significantly lower in affected dogs. No difference in serotonin serum level was seen between affected and healthy WHWT or between dogs with cIPF, CB or EBP. ET1 was evaluated as a biomarker in serum and BALF. ET1 serum concentration was not different between healthy WHWT and Beagles. Covariance analysis did not reveal any significant age effect. Serum levels were significantly higher in dogs with cIPF compared to dogs with CB or EBP. ROC curve analysis was then used to evaluate its diagnostic performances. The area under the curve was 0,818 with a sensitivity of 91.7% and a specificity of 87.5%. ET1 was also measured in the BALF in a small number of dogs. Its concentration was measurable in all dogs with cIPF while it was below the detection limit in all other dogs tested (healthy and with CB). Even though cIPF and human IPF are not completely identical from clinical, tomodensitometric or histological points of view, these results show that both canine and human diseases share molecular pathways, supporting the idea that cIPF might have an interest as spontaneous model. This work allowed a better understanding of cIPF pathogenesis. Gene expression analysis in the pulmonary parenchyma of affected dogs first identified several altered biological functions that should be analyzed in details in further studies. A more targeted analysis of some genes confirmed an upregulated expression of CCL2, CCL7, CXCL14, IL8 and FAP. Such a positive regulation of the expression of various inflammatory cytokines tends to suggest that inflammation might have a role in cIPF pathogenesis. Some of these cytokines also have profibrotic properties. PLUNC was one of the top down-regulated genes. Roles of the protein are still largely unknown; it might have a role in the inflammatory response and in the innate immunity. Developmental pathways were also altered in cIPF and quantitative RT-PCR confirmed an upregulation of FAP, a protein normally expressed in areas of tissue remodeling during fetal development and also positively regulated in human IPF. This study has shown that there is an active TGFB1 signal in the lungs of dogs with cIPF, especially at the level of the pathological epithelium. TGFB1 storage and activation pathways also seemed to be altered. Elevated TGFB1 circulating levels were found in predisposed breeds, which might explain at least partly their susceptibility for cIPF. Because of these results and its well-known profibrotic properties, we can suggest that TGFB1 is probably involved in cIPF pathogenesis and that modulation of its storage, activation or intracellular signaling might offer potential therapeutic targets. Our preliminary results are not in favor of a significant modification of the serotonin pathways in cIPF, although a decreased expression of 5HTT was seen in affected dogs and might have an impact on the amount of serotonin present locally. However, other studies are needed to conclude. Finally, several potential biomarkers have been identified and some of them were evaluated in details. While serum measurements performed for TGFB1 and serotonin indicated that these molecules have no interest as diagnostic biomarkers, ET1 and CCL2 were identified as interesting candidates with good diagnostic performances. However these results need to be confirmed in an independent validation cohort and the interest of combining both biomarkers should be evaluated. [less ▲]

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See detailValorisation de l’information pédologique numérisée pour la modélisation de la percolation des pesticides vers les eaux souterraines
Bah, Boubacar Billo ULg

Doctoral thesis (2014)

In Wallonia (southern Belgium), 81% of human drinking water is captured from groundwater tables. In spite of actions implemented under the European directives and thematic strategies, the required ... [more ▼]

In Wallonia (southern Belgium), 81% of human drinking water is captured from groundwater tables. In spite of actions implemented under the European directives and thematic strategies, the required standard (0.1 µg L-1 by pesticide and 0.5 µg L-1 for all pesticides) for human drinking water is most often exceeded at some catchments. Tools such as mechanistic models are appropriate since they allow an a priori estimation of pesticide concentrations leached at the bottom of soil profile, which could reach the groundwater tables. However, simulations often lead to a degree of uncertainty due to the approximations noted in the models, or due to the reliability of available data. The main objective of this thesis was to improve the usefulness of the Digital Soil Map of Wallonia (DSMW) and the associated soil analysis database named “Aardewerk” in the framework of the evaluation of the groundwater table contamination by pesticides, in order to reduce approximations associated with the GeoPEARL model and its meta-model MetaPEARL in the area of Condroz. In order to cover the broad spectrum of pesticides used in agriculture in Wallonia, nine theoretical pesticides have been defined. The first research question is to measure the sensitivity of GeoPEARL to two soil data parameterization schemes at the regional scale, depending on whether we first aggregate soil data at a regional scale before application of the model (AC approach); or we first apply the model to soil profiles and aggregate simulated leached concentrations afterwards (CA approach). The results show a significant difference between the two approaches, compared on the basis of a spatial threshold (80th percentile) calculated by soil type. Moreover, this difference varies depending on pesticide type, and is more important when the simulated concentrations are very low. It is also clear from this analysis that only pesticides located in certain ranges of DT50 (30 and 67 days) and Kom (58 and 252 dm3 kg-1) give concentrations more often above water potability standard of 0.1 µg L-1. The second research question is to calibrate MetaPEARL metamodel (simplified model) based on GeoPEARL simulated concentrations, from which it was derived by considering only the most sensitive parameters of GeoPEARL. The objective by developing a metamodel is to provide a simple tool, usable for a first evaluation of pesticides leaching in order to identify the most risk-prone areas, but also readily transposable for a global decision support system. In contrast to the approach of MetaPEARL calibration used until now, taking into account soil morphology through soil horizons (layers) types explains about 80% of the spatial variability of pesticide concentrations obtained from the complete original GeoPEARL model. The third research question is to take into account the spatial variability of input variables within the same soil typological unit using stochastic simulations to assess the uncertainty associated with deterministic simulations (taking into account average values by soil type for the input variables at the regional scale) obtained from MetaPEARL. The random spread of soil characteristics variability leads to a very significant spreading of simulated pesticide concentrations. Moreover, we obtain values of 80th spatial probabilistic percentile higher than those obtained from the deterministic approach. Consequently, for a risk mapping designed to aid decision-making tools, the probabilistic approach should be used since it allows, by taking into account the spatial variability of the model input parameters, to obtain more realistic concentrations of leached pesticides. [less ▲]

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See detailMOLECULAR TOOLS APPLIED TO THE STUDY OF MICROCYSTIN-PRODUCING CYANOBACTERIA IN BELGIAN WATERBODIES
Lara, Yannick ULg

Doctoral thesis (2014)

‘Blooms’, an increasing worldwide phenomenon, are adversely affecting surface water resource, including reservoirs and lakes, used for drinking water supplies, recreation, crop, irrigation and fisheries ... [more ▼]

‘Blooms’, an increasing worldwide phenomenon, are adversely affecting surface water resource, including reservoirs and lakes, used for drinking water supplies, recreation, crop, irrigation and fisheries. These amenities are affected by recurrent mass proliferations of cyanobacteria. The latter are responsible for the production of a wide range of bioactive compounds, including potent toxins (cyanotoxins). These comprise neurotoxins, cytotoxins, inflammatory agents, and hepatotoxins. Microcystins (MCs), hepatotoxins and tumour promoters are the most documented of the cyanotoxins. The microcystin synthetase gene cluster (mcy) involved in MC biosynthesis consists of a succession of non-ribosomal peptide synthase (NRPS) and polyketide synthetase (PKS) genes. The main producers of MCs are Anabaena, Microcystis, and Planktothrix. However, it is not possible to distinguish a toxic from a non-toxic strain on the basis of their morphology. In the present study, molecular tools were used, optimized and developed to (i) characterize the 16S rRNA gene diversity of planktonic cyanobacteria, (ii) to detect the cyanobacteria responsible for the production of MCs, (iii) to identify the MCs producing taxa, and (iv) to determine the environmental factors that influence the dynamic of toxic and non-toxic genotypes in Belgian freshwaters. Eighty-nine strains were isolated and their 16S rRNA genes sequenced. The 16S rRNA gene diversity was studied in 32 samples by denaturing gradient gel electrophoresis (DGGE). In order to evaluate the contribution of this work to the study of the molecular diversity of cyanobacteria in Belgian waterbodies, 114 (strains and DGGE) sequences obtained during this PhD thesis were compared to Belgian sequences obtained by others. As a result, 14 previously undiscribed operational taxonomic units (OTUs) were found in the present study. For polymerase chain reaction (PCR) detection of the mcyA/B/E genes, the DNA from a total of 162 environmental samples was extracted. The three genes were found together in 64.2% of the samples, whereas the mcyB alone was detected in 95.1% of the samples. In order to identify the mcyE-carriers present in the freshwaters, a restriction fragment length polymorphism (RFLP) was performed on the mcyE gene. The presence of potentially toxic Microcystis was observed in most of the cases.To bypass the constraint of bacterial cultivation, a combination of whole genome amplification (WGA) and enzyme-linked immunoassay (ELISA) was tested on individual colonies of members of two cyanobacteria, Microcystis and Woronichinia, directly from the natural environment. Sequences of 3 different housekeeping genes (ftsZ, gltX, and recA), of 3 mcy genes, and the Internal Transcribed Spacer (ITS) were analyzed for 11 colonies of Microcystis. MCs were detected and quantified by ELISA in 7 of the 11 Microcystis colonies tested, in agreement with the detection of mcy genes. Sequence types (ST) based on the concatenated sequences of housekeeping genes from cyanobacterial colonies from Belgian water bodies appeared to be endemic when compared to those of strains described in the literature. One colony belonged to a yet undiscovered lineage. A similar protocol was used for 6 colonies of the genus Woronichinia, a taxon that is very difficult to cultivate in the laboratory. The 16S rRNA analysis confirmed the colony identification based on morphology. In addition, we obtained for the first time new genetic data for this genus, such as the rpoC1 gene sequences and the sequences and secondary structures of the ITS. The first discovery of NRPS and PKS DNA sequences in Woronichinia colonies highlights the need for further study of this widely occurring genus, to better assess its ability to produce MCs and/or related metabolites. For the first time, in this study, we were able to simultaneously monitor one toxic and one non-toxic genotype of M. aeruginosa using real time qPCR technology during a monitoring of 2 years. Both toxic and non-toxic genotypes dynamics appeared influenced by the photoperiod. In addition, the dynamic of the toxic genotype was influenced of light intensity. The results obtained during this PhD research show the need to characterize toxic cyanobacteria in freshwaters, as well as the conditions that influence MCs concentration dynamics. We showed that factors controlling the dynamics of toxic and non-toxic genotypes are complex. Nevertheless, detection tools can be developed to better understand these widely occurring phenomena. Therefore, efforts should go on in this field with collaborations between the scientists and the authorities. [less ▲]

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See detailBiologie de la reproduction et analyse du déterminisme et de la différenciation du sexe à des stades précoces chez le tilapia du Nil, Oreochromis niloticus
Gennotte, Vincent ULg

Doctoral thesis (2014)

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental ... [more ▼]

La reproduction des poissons téléostéens se caractérise par une diversité des types de sexualité (gonochorisme vs hermaphrodisme) et des systèmes de déterminisme du sexe (génétique et/ou environnemental), ainsi que par une plasticité du contrôle génétique et endocrinien de la différenciation sexuelle incomparables parmi les autres vertébrés. Le tilapia du Nil (Oreochromis niloticus) est un cichlidé gonochorique possédant un système chromosomique de déterminisme sexuel à homogamétie femelle XX/XY, complété par un déterminisme environnemental, les hautes températures pouvant modifier le développement phénotypique du sexe. L’intérêt porté à cette espèce en aquaculture à conduit au développement de différentes techniques de contrôle du sexe (par traitement hormonal) permettant la production de poissons présentant différentes combinaisons de phénotype/génotype sexuels (mâles XX, XY, YY, femelles XX, XY et YY). Ces derniers constituent des outils majeurs de l’étude du déterminisme et de la différenciation du sexe et soulèvent de nombreuses questions concernant les interactions génotype/phénotype sexuels chez cette espèce. Au regard de ces considérations, nous nous sommes fixés 2 objectifs principaux : 1. Déterminer l’influence du génotype sexuel sur certains aspects liés à la biologie reproductive chez le tilapia du Nil tels que la qualité du sperme, les taux de stéroïdes sexuels (testostérone, T ; 17β-œstradiol, E2 ; 11-cétotestostérone, 11KT) et les comportements agressifs. Le génotype sexuel ne semble pas avoir d’influence sur la qualité gamétique des mâles, puisqu’aucune différence n’est observée entre les individus XX, XY et YY, alors que paradoxalement, les taux de 11KT sont plus élevés chez les mâles XX. De la même manière, les femelles présentent des taux croissants d’E2 chez les individus XX, XY et YY. Ces différences de taux de stéroïdes sexuels pourraient être liées aux taux d’agressivité (évalué par la quantification de huit comportements agonistiques dans des confrontations mâle-femelle) plus élevés des mâles XX et des femelles XY et YY et engendrer des perturbations des comportements reproducteurs. Des recherches complémentaires sont nécessaires d’une part, pour évaluer l’effet du génotype sur la qualité des gamètes des femelles et d’autre part, pour déterminer si les modifications phénotypiques observées sont liées à l’expression du génotype sexuel ou à des perturbations engendrées par les traitements hormonaux d’inversion sexuelle administrés durant la période de différenciation des gonades. 2. Explorer les mécanismes du déterminisme et de la différenciation à des stades précoces du développement. Grâce à la mise au point d’une technique d’inversion sexuelle ciblant les périodes embryonnaire et larvaire (avant 10 jpf) par des expositions courtes (4h) d’embryons âgés d’un jpf à des androgènes (11KT, 17α-méthyltestostérone), un inhibiteur de l’aromatase (Fadrozole) ou un œstrogène (17α-éthynylœstradiol), nous avons confirmé l’existence d’une période sensible de la différenciation sexuelle avant le développement des gonades. Les voies de différenciation phénotypique semblent être différentes en fonction du génotype, puisque la masculinisation des embryons XX est moins efficace (max 10%) que la féminisation d’embryons XY (max 91%). De la même manière, un probable effet chromosomique rend inefficace la féminisation d’embryons YY. La féminisation des individus XY est concomitante avec une augmentation des taux de T et d’E2 et d’expression de l’aromatase cérébrale à 4 jpf qui pourrait indiquer un rôle précoce du cerveau dans la différenciation sexuelle. Dans l’ensemble, nos résultats nous permettent de suggérer, d’une part, que les premiers événements moléculaires de la différenciation sexuelle du tilapia sont initiés avant la formation des gonades, et d’autre part, que chez les individus sexuellement inversés, des différences sexuelles peuvent apparaître dans le cerveau avant ou en même temps que le développement des gonades et induire des modifications comportementales à l’âge adulte. La question du rôle possible du cerveau dans la différenciation des gonades reste ouverte. [less ▲]

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See detailOrigin and properties of the two-dimensional electron gas at the LaAlO3/SrTiO3 interface: a first-principles hybrid functional study.
Fontaine, Denis ULg

Doctoral thesis (2014)

Complex oxides exhibit a wide range of physical properties making them very attractive for future electronic and device applications. Although more and more studied, additional scientific investigations ... [more ▼]

Complex oxides exhibit a wide range of physical properties making them very attractive for future electronic and device applications. Although more and more studied, additional scientific investigations are required, especially in oxide interfaces, where new and amazing phenomena can arise. A prototypical example is the LaAlO3-SrTiO3 interface that appear to be conducting, magnetic or even supra-conducting while these properties are not present in the LaAlO3 and SrTiO3 bulk insulator compounds. The conductivity arises from the formation of a highly localized electron gas at the interface which exhibits a different behavior than the one at semiconductor interfaces. Even nowadays, its exact origin, intrinsic versus extrinsic, is still intensively debated. The existence of an electric field in LaAlO3 used as a key feature of models based on an intrinsic origin is highly controversial. In these models, the closing of the band gap with increasing LaAlO3 film thicknesses finally results to a Zener breakdown and to the metal/insulator transition. In this Ph.D. thesis we aim to investigate the various consequences of the presence of an electric field in LaAlO3 through first-principles calculations in pristine LaAlO3-SrTiO3 interfaces. First, using both experimental and theoretical structural distortions in LaAlO3, we predicted a lattice expansion via an electrostrictive effect, supporting the existence of an electric field in LaAlO3. Second, the metal/insulator transition was tuned with regards to the intensity of the electric field in the film, which was controlled by the composition of a solid solution between LaAlO3 and SrTiO3. The theoretical results match the experimental one where, nevertheless, extrinsic origin mechanisms are allowed and defects are present. These two works are in favors of an intrinsic origin of the electronic gas observed in LaAlO3-SrTiO3 heterostructures. In addition, a relationship between the sheet carrier density and spatial extension of the gas was established and thus setting an intrinsic threshold to the sheet carrier concentration. At lower density the electrons are strictly localized close to the interface while above this value the carriers start to spill into the SrTiO3 substrate. [less ▲]

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See detailAnalyse de la variabilité naturelle du climat : application à l’aide des ondelettes
Mabille, Georges ULg

Doctoral thesis (2014)

Ce travail a pour but de mettre en évidence des cycles méconnus et cachés de la transformée de Fourier dans les séries temporelles liées au climat. Les périodes recherchées, à l’aide de l’outil ondelettes ... [more ▼]

Ce travail a pour but de mettre en évidence des cycles méconnus et cachés de la transformée de Fourier dans les séries temporelles liées au climat. Les périodes recherchées, à l’aide de l’outil ondelettes développé à l’Institut de Mathématique de l’Université de Liège, sont de l’ordre de quelques dizaines de mois. [less ▲]

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See detailL'organisation spatiale des pôles de compétitivité en Wallonie. Vers une nouvelle géographie économique du territoire wallon ?
Wilmotte, Pierre-François ULg

Master of advanced studies dissertation (2014)

The aim of this work is to present the spatial organization of the six Walloon clusters. Their spatial structure is considered under two approaches: first, the proximity question with the stakeholders of ... [more ▼]

The aim of this work is to present the spatial organization of the six Walloon clusters. Their spatial structure is considered under two approaches: first, the proximity question with the stakeholders of R&D projects and then the question of the Walloon territorial division. The methodology examines different kinds of proximity (social, geographic,...) thanks to a cartographical and statistical analysis. The results reveal the competitive area of Wallonia and the importance of geographical proximity between the stakeholders of innovative projects. [less ▲]

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See detailMultiscale Finite Element Modeling of Nonlinear Quasistatic Electromagnetic Problems
Niyonzima, Innocent ULg

Doctoral thesis (2014)

The effective use of composite materials in the technology industry requires the development of accurate models. Typical such materials in electrotechnical applications are lamination stacks and soft ... [more ▼]

The effective use of composite materials in the technology industry requires the development of accurate models. Typical such materials in electrotechnical applications are lamination stacks and soft magnetic composites, used in the so-called magnetoquasistatic (low frequency) regime. Current homogenization models (e.g. the classical homogenization method, mean field homogenization, ...) fail to handle all the difficulties raised by the modeling of these materials, particularly taking into account the complexity of their microstructure and their nonlinear/hysteretic behaviour. In this thesis we develop a multiscale computational method which allows to effectively solve multiscale magnetoquasistatic problems. The technique is inspired by the HMM (heterogeneous multiscale method), which involves the resolution of two types of problems: a macroscale problem that captures slow variations of the overall solution, and many mesoscale problems that allow to determine the constitutive laws at the macroscale and to construct accurate local fields. Macroscale and mesoscale weak, b-conform and h-conform formulations, are derived starting from the two-scale convergence and the periodic unfolding methods. We also use the asymptotic homogenization method for deriving the homogenized linear material laws and, in the end, we derive scale transitions for bridging the scales. Numerical tests carried out in the two-dimensional case allow to validate the models. In the case of b-conform formulations, it is shown that the macroscale solution approximates well the average of the reference solution and that the resolution of the mesoscale problems allows to reconstruct accurate local fields and to compute accurate Joule losses and this, for materials with (non)linear and hysteretic behavior. Similar findings were obtained for the h-conform formulations. In both cases, the deterioration of the accuracy for mesoscale problems located near the boundary of the computational domain could be treated by defining suit- able mesoscale problems near such boundaries. The extension of the model to three-dimensional problems, to multiphysical problems and the inclusion of the mesoscale domains with a stochastic distribution of phases are also some of the possible prospects for improving this work. [less ▲]

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See detailDéveloppement de nouvelles méthodes de marquage au fluor-18 pour peptides et oligonucléotides en vue de leur études par tomographie par émission de positons
Flagothier, Jessica ULg

Doctoral thesis (2014)

Positron Emission Tomography is a highly sensitive imaging technique currently available in nuclear medicine for diagnostic. In regard to his physical and nuclear characteristics, fluorine-18 appears ... [more ▼]

Positron Emission Tomography is a highly sensitive imaging technique currently available in nuclear medicine for diagnostic. In regard to his physical and nuclear characteristics, fluorine-18 appears often as the radionuclide of choice for the preparation of short-lived positron-emitter radiotracers for PET studies. The fluorine-18 labelling reaction for biomolecules requires very mild conditions. The current method for highly efficient fluorine-18 labelling of biomolecules is the conjugation of a [18F]prosthetic group with a reactive function on the organic compound. During this thesis, two techniques were developed to label biomolecules via a [18F]prosthetic group: the first one to label tyrosine-containing peptides and the second one to label a siRNA. The first part of this work present the synthesis of the [18F]F-PTAD which is a agent for specific radiolabelling of tyrosine. [18F]F-PTAD was coupled with a tyrosine with a global radiochemical yield (synthesis, coupling, purification) of 20% (DC) and the synthesis lasts 2h30. During the second part of this work, two alkyne-bearing linkers were synthesized. These linkers were ligated with siRNA and then reacted with azide-bearing [18F]prosthetic group via a Huisgen cycloaddition reaction. The [18F]siRNA is then obtained with an global radiochemical yield of 12% (DC) and the synthesis lasts 2h00. In conclusion, two methods for labeling biomolecules have been developed. [less ▲]

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See detailFamily from afar: Moroccan migration, family practices and the transnational social space
Zickgraf, Caroline ULg

Doctoral thesis (2014)

This dissertation is situated at the crossroads of migration, family and transnational studies. It explores families that span multiple cities and countries due to the migration of one or more relatives ... [more ▼]

This dissertation is situated at the crossroads of migration, family and transnational studies. It explores families that span multiple cities and countries due to the migration of one or more relatives and analyzes their subsequent construction and reconstruction of familyhood across national borders. Through a multi-sited qualitative study into Moroccan family networks with residential nodes in Liège, Belgium and Oujda, Morocco, but also several other destinations, Caroline Zickgraf considers both the material and non-material functions of transnational family practices that together produce and inflate transnational social spaces. She treats both the social and physical geographies of these networks in order to understand how the circulation of people affects the circulation of care but also treats the tensions and asymmetries that characterize their multi-directional cross-border exchanges. [less ▲]

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See detailEconomic statistical design of nonparametric control charts
Marcos Alvarez, Alejandro ULg

Master's dissertation (2014)

In this work, we apply the economic statistical design framework to nonparametric control charts. To this end, we develop bounds for the type II error probability, i.e. the false negatives rate, of the ... [more ▼]

In this work, we apply the economic statistical design framework to nonparametric control charts. To this end, we develop bounds for the type II error probability, i.e. the false negatives rate, of the nonparametric charts that are then used within the model. We implement the optimization problem defining economic statistical design and use it to find the design parameters of nonparametric control charts. We then compare the behavior of this design with parametric and nonparametric charts on different probability distributions with different values of the distribution parameters. We finally perform a brief analysis of the obtained results that emphasizes the differences between the economic statistical design of parametric and nonparametric control charts. In this study, we also give a number of advantages and shortcomings of both approaches so that the interested reader can make the best possible decision on which control chart it is better to use for a given application. [less ▲]

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See detailCARACTÉRISATION DE LA DIVERSITÉ GÉNÉTIQUE DE CULTIVARS D’OIGNON (ALLIUM CEPA L.) DU NIGER EN VUE DE LEUR CONSERVATION IN SITU ET DE LEUR AMÉLIORATION
Abdou, Rabiou ULg

Doctoral thesis (2014)

Plante monocotylédone, allogame, entomophile, avec un cycle cultural annuel pour la production des bulbes, bisannuel pour celle des graines, l’oignon est l’un des légumes le plus important au Niger en ... [more ▼]

Plante monocotylédone, allogame, entomophile, avec un cycle cultural annuel pour la production des bulbes, bisannuel pour celle des graines, l’oignon est l’un des légumes le plus important au Niger en raison de son utilisation en alimentation et en médecine. Le semis en pépinière suivi d’un repiquage des planches est le mode de culture le plus fréquent chez les producteurs nigériens. Cette étude explore la diversité génétique des cultivars d’oignon du Niger. La diversité est à comprendre ici au sens de la diversité nommée, la diversité morphologique et la diversité moléculaire. Cette thèse se propose d’utiliser ces trois approches complémentaires pour identifier et caractériser les variétés et écotypes selon la perception des producteurs, de caractériser la diversité morphologique et agronomique à partir des descripteurs du genre Allium établis par Bioversity International, et d’analyser la diversité moléculaire des variétés et écotypes d’oignon du Niger à partir des marqueurs moléculaires microsatellites. Cinquante-deux écotypes nommés ont été inventoriés, mais après analyse et regroupement des synonymes, il ressort que dix-sept écotypes sont cultivés au Niger. Les principaux critères des paysans pour caractériser un écotype local sont la couleur des bulbes et la zone de provenance. Les variables quantitatives et qualitatives les plus distinctives entre les écotypes d’oignon sont la longueur et le diamètre des feuilles, le poids des bulbes, la couleur des feuilles, la forme et la couleur des bulbes, l’uniformité de la forme et de la couleur des bulbes. La distance génétique est plus grande, d’une part, entre les écotypes les plus éloignées géographiquement, et d’autre part, entre les écotypes les plus différents au niveau des caractères morphologiques. Le nombre de morphotypes varie de un à neuf par écotype testé. Les analyses moléculaires confirment la forte variabilité à l’intérieur des écotypes et les conclusions relatives à la distance génétique observée à partir des données morphologiques. A l’issue de ces travaux de caractérisation génétique de l’oignon, il est donc utile de combiner des stratégies de conservation in situ et ex situ, et l’exploitation de ces ressources génétiques pour améliorer la production et la rusticité des cultivars d’oignon du Niger. [less ▲]

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See detailMulti-period Stochastic Optimization Problems in Transportation Management
Pironet, Thierry ULg

Doctoral thesis (2014)

The topic of this thesis in management science is to propose a methodology to tackle multi-period decision problems including stochastic forecasts and to apply it to the field of transportation management ... [more ▼]

The topic of this thesis in management science is to propose a methodology to tackle multi-period decision problems including stochastic forecasts and to apply it to the field of transportation management. This methodology relies mostly on a sequence of numerical experimentations based on a set of algorithms to assess the value of the multi-period setting and the interest to use the stochastic information contained in the forecasts. Moreover, a statistical validation method to compare the performances of algorithms enables us to rank them meaningfully. From theory to practice, the thesis is structured into four parts. Firstly, we define the thesis subject and content. Then, based on a literature review, we present the past and present issues within the research field: "Optimization in Transportation". Mainly, we define the differences between multi-period stochastic models and classical deterministic mono-period ones. We explain how dynamism and stochasticity are taken into account within transportation problems. Secondly, our methodology, which is our main contribution, is exposed from a generic point of view in the theoretical research field: "Multi-period Stochastic Optimization Problems". On the one hand, temporal parameters and computational issues in multi-period optimization are detailed; on the other hand a summary of optimization techniques and algorithms for stochastic optimization problems is provided. Afterwards, the statistical validation of algorithmic performance is discussed. Then, part three contains two applications that lead us to set up the methodology, following an inductive method. The first problem, based on an industrial application at the start of the research, investigates a "multi-period vehicle loading problem with stochastic release dates". The second application, based on a more generic approach for the deployment of the methodology, deals with a "multi-period vehicle assignment problem with stochastic load availability". Finally, in the fourth part, we conclude on the thesis contributions and propose some perspectives. [less ▲]

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See detailEtude de l'implication de cellulases dans la voie de biosynthèse de cellulose chez les bactéries
Delsaute, Maud ULg

Doctoral thesis (2014)

By definition, cellulases are enzymes that catalyze the degradation of cellulose. However, their involvement in cellulose biosynthesis by bacteria and plants has been reported, although their exact ... [more ▼]

By definition, cellulases are enzymes that catalyze the degradation of cellulose. However, their involvement in cellulose biosynthesis by bacteria and plants has been reported, although their exact contribution remains unclear. In the present study, we have investigated the involvement of cellulases from glycoside hydrolase family 5 (GH5) in cellulose synthesis. In particular, we have functionally and structurally characterized the Ps_Cel5A cellulase from Pseudomonas stutzeri and its metagenome-derived homolog RBcel1, which both belong to the GH5 family and are suspected to be involved in cellulose biosynthesis. In addition, we have also compared these enzymes with the well-characterized Ta_Cel5A cellulase from the cellulolytic fungus Thermoascus aurantiacus. The first part of the work was devoted to the description of the tridimensional structure of RBcel1, in comparison with other glycoside hydrolases from GH5. In the second part of the study, we focused on the functional and structural comparison between RBcel1, Ps_CelA and Ta_Cel5A. Biochemical analysis has highlighted that, besides their hydrolytic activity, RBcel1 and Ps_Cel5A were able to catalyze transglycosylation in vitro. This synthesis reaction was not detected for Ta_Cel5A, which seemed to remain hydrolytic only. Determination of the structure of RBcel1 in complex with cellobiose has revealed distinct features in the aglycone substrate binding sites compared to Ta_Cel5A which could potentially explain the observed differences in their activities in vitro. Finally, the involvement of Ps_Cel5A in cellulose production by P. stutzeri was confirmed, by analysis the ability of P. stutzeri-ΔPs_Cel5A to produce the polymer. Complementation of this mutant strain by the three cellulases was also performed and discussed. [less ▲]

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See detailPost-Science Fiction and the Post-Posthuman
Guesse, Carole ULg

Master's dissertation (2014)

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See detailLes effets délétères métaboliques et oxydants induits lors d'un sepsis sur la fonction rénale
Quoilin, Caroline ULg

Doctoral thesis (2014)

Acute kidney injury (AKI) is a frequent complication of sepsis that can increase mortality as high as 70%. The pathophysiology of this kidney failure was previously believed to be secondary to decreased ... [more ▼]

Acute kidney injury (AKI) is a frequent complication of sepsis that can increase mortality as high as 70%. The pathophysiology of this kidney failure was previously believed to be secondary to decreased global renal perfusion causing hypoxia-induced injury. However, new research suggests this paradigm is overly simplistic, and injury is now considered multifactorial in origin. Mechanisms that contribute to kidney injury mainly include inflammation, alterations in microvascular renal blood flow and changes in bioenergetics. To study the mechanism of oxygen regulation in acute kidney injury during sepsis, we developed a sepsis-induced in vitro model using proximal tubular epithelial cells (HK-2) exposed to a bacterial endotoxin (lipopolysaccharide, LPS). Our first investigation, by using both high-resolution respirometry and electron spin resonance spectroscopy, showed that HK-2 cells exhibit a decreased oxygen consumption rate when treated with LPS. Surprisingly, this cellular respiration alteration persists even after the stress factor is removed. We suggested that this irreversible decrease in renal oxygen consumption after LPS challenge is related to a pathologic metabolic down-regulation such as a lack of oxygen utilization by cells for ATP production. In the long term, this metabolic disturbance leads cells to a predominantly apoptotic death. To confirm this hypothesis of cytopathic hypoxia, we demonstrated that this alteration in the renal respiratory function is mainly due to an impairment in the metabolic activity of HK-2 cell mitochondria. Following LPS treatment, the oxidative phosphorylation is interrupted because of the inhibition of cytochrome c oxidase activity. As a consequence, disruptions in the electron transport and the proton pumping across the system occur, leading to a decrease of the mitochondrial membrane potential, the release of apoptotic-inducing factors and a decrease in ATP production. To clarify the mechanism by which the LPS induces mitochondrial alterations, we studied the oxidative stress generation in HK-2 cells. Interestingly, we revealed that the induction of a cytosolic oxidative stress is an event that appears before mitochondrial dysfunction in the LPS-treated HK-2 cells. This primary redox state is notably due to the activation of the two enzymes NADPH oxidase 4 and inducible NO synthase. The simultaneous production of anion superoxide and nitric oxide strongly suggests the formation of peroxynitrite, a relative stable powerful oxidant that can diffuse through mitochondrial compartments and undergo cytotoxic reactions. To our knowledge, our model reveals for the first time the role of NADPH oxidase-derived cytosolic ROS in triggering tubular cell damage. Moreover, after being first target of the oxidative stress, mitochondria become in turn producer of reactive oxygen species that carry on mitochondrial dysfunction. It seems thus that a mechanism of oxidative stress-induced redox cycling is a main cause of the mitochondrial dysfunction of LPS-treated HK-2 cells. The role of oxidants in mitochondrial dysfunction was further confirmed by the use of iNOS inhibitors or antioxidants that preserve cytochrome c oxidase activity and block mitochondrial membrane potential dissipation. Overall, these results suggest that sepsis-induced AKI should not only be regarded as failure of energy status but also as an integrated response, including transcriptional events, ROS signaling, mitochondrial activity and metabolic orientation such as apoptosis. [less ▲]

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See detailContribution à l'étude de l'optimum technico-économique de l'intervalle vêlage chez les vaches laitières en Wallonie, plus particulièrement en Région herbagère liégeoise
Dalcq, Anne-Catherine ULg

Master's dissertation (2014)

The calving interval (CI) is extending with potential impacts for the dairy breeders. In this way, the aim of this master thesis is to contribute to the study of the technicoeconomic optimum of the CI of ... [more ▼]

The calving interval (CI) is extending with potential impacts for the dairy breeders. In this way, the aim of this master thesis is to contribute to the study of the technicoeconomic optimum of the CI of dairy cows in Walloon Region of Belgium, especially in the “Région herbagère liégoise”. To this purpose a total of 1318 balance sheets, collected between 2007 and 2012 on 373 commercial dairy farms, were studied. Uni- and multivariate analyses were conducted, as well as a separation of the typological variability of the farms, in order to bring to light a link between the CI and the technicoeconomic variables and more particularly the gross margin per cow milked (GMCM) and thus to define an economic optimum of CI. A mean CI of the herd and a representative CI (which is the most common CI in the herd) have been assigned to each balance sheet. Moreover, surveys have been conducted with 5 dairy breeders and 22 Walloon vets in order to confront the results obtained with the situation in the field. On the basis of the obtained results, it can be observed that the relationship between the CI and the GMCM is weak (R = -0,085) and that the GMCM of the observations herd*year of the class representative short CI and the class representative long CI is not significantly different between these two classes (P-value > 0,05). The GMCM of the farms with short CI tend to be built up in the same way as with the long CI, except that the farms with long CI appears to depend even more on the milk price and the farms with short CI on the livestock costs. Because of the low impact of the CI on the economical results, a single technical and economical optimum of the CI has not emerged. The study of the typological variability of the best farms according to their economical results shows that the mean CI tends to rise with the intensification of the feeding and the increase of the level of the dairy production of the farms (coefficient of the linear trendline = 2,52, R2 = 66,83%). It therefore seems that the technicoeconomic optimum of CI tends to vary depending on the typology of the exploitation and to increase with the two herd parameters mentioned above. However, according to the surveys, the CI of the herd seems to be partly unknown by the breeders and more undergone than wished. Raising awareness of the breeders of the CI of their herd, gathering individual data as well as additional data in order to continue the study of the typological variability of farms are future options to explore in order to validate the results obtained and to provide ways of improvement to the breeders. [less ▲]

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See detailIntégration perceptive et mémoire épisodique dans la maladie d'Alzheimer
Delhaye, Emma ULg

Master's dissertation (2014)

Binding (i.e., to link different components together) is a key mechanism for episodic memory formation. Normal aging is characterized by a decrease in episodic memory for associations. However ... [more ▼]

Binding (i.e., to link different components together) is a key mechanism for episodic memory formation. Normal aging is characterized by a decrease in episodic memory for associations. However, associative memory performance can be improved and age-related differences can even be suppressed when associations are unitized, that is when they are encoded as an integrated whole. A previous study in Alzheimer's disease (AD) showed that patients do not benefit from this particular type of encoding in episodic memory, so that their performance for unitized representations remains very poor. The aim of the current study was to assess whether the unitization mechanism itself (i.e., to integrate components into a whole) is impaired in AD or whether a global memory impairment affects all kinds of representations (unitized and non-unitized). We evaluated this hypothesis in fifteen mild Alzheimer patients and twenty healthy control participants. To systematically increase the demands on unitization, pictures of objects and animals were either left intact, separated into two fragments, or separated into four fragments. Participants viewed the pictures and had to unitize them first in order to recognize it and judge whether it would fit into a shoebox. In a subsequent recognition test where all pictures were intact, they had to retrieve pictures they saw earlier. An analysis of correct recognition of studied pictures showed a significant interaction between group and fragmentation level, indicating a decrease in Alzheimer patients’ performance compared to control participants for pictures that were fragmented at study but not for pictures that were intact at encoding. These findings suggest that the perceptual mechanism of unitization of fragmented stimuli is impaired in Alzheimer's disease. [less ▲]

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See detailApport de la pédologie au conseil de fumure personnalisé par l’intégration d’arguments morphospatiaux et physico-chimiques impliquant de nouveaux outils d’analyse : la carte numérique des sols de Wallonie et la spectroscopie proche infrarouge
Genot, Valérie ULg

Doctoral thesis (2014)

The current environmental and agronomical context requires that farmers manage their inputs with the utmost precision, which can only be achieved by developing state of the art tools leading to clear ... [more ▼]

The current environmental and agronomical context requires that farmers manage their inputs with the utmost precision, which can only be achieved by developing state of the art tools leading to clear, exhaustive and efficient decisions. In this context, soil analysis being a vital tool, we have endeavoured to refine the advice given to farmers by the Walloon soil analysis laboratories, members of the non-profit-making organization REQUASUD, by studying the opportunity of developing two complementary tools, one cartographic, the other analytical, which can be integrated in the daily running of a laboratory. First of all, to ensure that soil analysis provides reliable results, it is essential for the sample to be as representative as possible of the plot. Lacking this representativity, an analytical result, however accurate, would be devoid of meaning and give the farmer misleading advice. In the field, the main obstacle for the soil sampler is the recognition of soil criteria which are however essential in establishing fertility advice, especially in Wallonia (southern Belgium) due to a high soil variability. The Digital Soil Map of Wallonia, surveyed at a scale of 1/5000, should prove to be an invaluable tool that can be used easily and directly for routine work not only by soil samplers but also by farmers and agronomists. That’s why a mapping web portal REQUACARTO has been designed to help define homogenous morpho-pedological areas and to validate them in different situations. Furthermore, in Wallonia, certain soil properties seldom undergo routine analysis, despite their importance in fertility advice, and when they do, they result in the use of extracts which are harmful to the environment and to health. Therefore we investigated the feasibility of a routine application of near infrared reflectance spectroscopy (NIRS) to determine these soil properties. This technique offers a number of advantages compared to analyses carried out according to reference methods: speed, respect of the environment and health, recovery of the sample, ease of use and thus economy. On a selection of representative samples of the pedological context of Wallonia, for which we also had analytical results of exchange cation capacity, as well as rates of carbon, nitrogen and clay, trials were performed using NIRS instead of or in addition to laboratory reference analyses. The findings highlight the relevance of using NIRS and were substantiated by a study of repeatability and intermediate precision of the technique. The spectral library was then transferred to the different soil analysis laboratories of the network. The goal is multiple: to offer further analyses to farmers at no extra cost, reduce the number of analyses performed according to reference methods and implement the spectral library with samples not predicted by NIRS to improve predictions. [less ▲]

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See detailEvaluation de la pertinence du couplage entre le modèle régional MAR et le modèle de calotte glaciaire GRISLI sur le Groenland
Wyard, Coraline ULg

Master's dissertation (2014)

During the two last decades, the Greenland ice sheet (GrIs) contribution to the global mean sea level (GMSL) rise has significantly increased. In the future, difficulties remain to assess the GrIs ... [more ▼]

During the two last decades, the Greenland ice sheet (GrIs) contribution to the global mean sea level (GMSL) rise has significantly increased. In the future, difficulties remain to assess the GrIs contribution to GMSL rise because of large uncertainties linked to the feedback between the surface mass balance (SMB) and the elevation of the GrIs. In 2013, Xavier Fettweis, my promoter, has coupled a regional climate model (RCM), the model MAR, with an ice sheet model (ISM), the model GRISLI, in order to account of this feedback and, in this way, to improve the assessment of the future GrIs contribution to the GMSL rise. The aim of this study is to assess the pertinence of the MAR−GRISLI coupling which requires long computation time. Nine imulations were carried out with GRISLI. Six of these simulations consisted in forcing GRISLI with several present days MAR outputs (SMB and surface temperature) in order to identify the GRISLI biases. The three last simulations consisted in forcing GRISLI until 2100 with future non-coupled, coupled and modified non- coupled MAR outputs in order to find a technique to avoid the coupling. The results show that initial conditions need to be improved and that the ice flow velocities required recalibration because an abnormal present-day thickening of the GrIs margins. Ice calving only depends on ice sheet extension because of constant ice flow velocities. The MAR−GRISLI coupling can be avoided until the middle of the 2080s. Beyond these years, the SMB correction is too large so that the thinning of the GrIs margins is overestimated. In a further study, the SMB correction could be reduced to avoid the MAR−GRISLI coupling over longer periods. GRISLI could be improved or replaced by a more complex ISM with dynamic ice flow velocities to enhance the results. [less ▲]

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See detailModeling risk and expected returns in finance and macroeconomics
Lejeune, Thomas ULg

Doctoral thesis (2014)

This doctoral dissertation contributes to the modeling of risk and expected returns in the fields of finance and macroeconomics. On the finance side, the thesis proposes a portfolio choice model and a ... [more ▼]

This doctoral dissertation contributes to the modeling of risk and expected returns in the fields of finance and macroeconomics. On the finance side, the thesis proposes a portfolio choice model and a risk-return setup that simultaneously deal with agents’ unknown utility function, incomplete knowledge of financial return distributions, departures from the Gaussian distribution (i.e. asymmetry and fat-tail risks), investment horizons and investors’ objectives in terms of expected returns. On the macroeconomic side, the objective is to deliver a comprehensive picture of the financial sector in a general equilibrium framework, which accommodates the heterogeneity of behaviors within financial intermediaries. The first part of the thesis introduces an innovative risk measure, risk horizon, with reference to the speed of convergence of an asset’s mean return to its expectation. This measure is a keystone to a general framework for characterizing investors’ behavior in portfolio selection, which takes into account consideration for volatility, asymmetric and fat-tail risk, a trade-off between downside and upside potential of financial assets, and the timing and probability of deviations from expected returns. The risk horizon framework opens up the way to the identification of forward-looking determinants of market sentiment that includes, among others, the expected market and credit returns. The last part of the thesis is devoted to a macroeconomic model with heterogeneous and financially constrained intermediaries. An analysis of endogenous risk mechanisms when traditional and shadow banking interact is carried out. The model sheds light on the importance of relative leverage behaviors in the amplification of adverse shocks in the economy. [less ▲]

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See detailApproche hédonique du marché des terrains à bâtir : Modélisation des prix dans les bassins d'emploi de Liège et de Charleroi, comparaison interbassin et évolution temporelle liégeoise
Maldague, Hubert ULg

Master's dissertation (2014)

The study focuses on modeling the price of building land by the hedonic approach in the Liège and Charleroi areas, Belgium. We test a lot of location variables in addition to some structural variables to ... [more ▼]

The study focuses on modeling the price of building land by the hedonic approach in the Liège and Charleroi areas, Belgium. We test a lot of location variables in addition to some structural variables to define their influence on price formation. We show that the location variables have a more or less important role, sometimes questionable, and we discuss these results. [less ▲]

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See detailETUDE DE LA DYNAMIQUE DES ARN DANS LE NUCLÉOLE DES CELLULES DE REPTILES
Bartholomé, Odile ULg

Master's dissertation (2014)

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See detailInteractions in massive binaries: spectral modelling – CoMBiSpeC – and observational analyses
Palate, Matthieu ULg

Doctoral thesis (2014)

Massive stars are very important to the life of the galaxiesbut they are rare and many open questions on their formation, evolution and characteristics remain. One of the best ways to improve our ... [more ▼]

Massive stars are very important to the life of the galaxiesbut they are rare and many open questions on their formation, evolution and characteristics remain. One of the best ways to improve our knowledge on massive stars is to study massive binaries (that represent at least 50% of massive stars see Mahy et al. 2009, and Sana & Evans 2011) and their spectra. Spectral and atmosphere modelling of stars are very interesting tools that are now often used in spectral analyses. However, these models are designed for single spherical stars. In this context, we have developed a numerical code of spectral modelling of massive binary systems: CoMBiSpeC (code of massive binary spectral computation) that computes the spectra of massive binary systems and accounts for various effects that affect these systems. Our models, and the observational analyses of the four binary systems presented in the second part of this work, have allowed to explain several effects linked to binarity: luminosity class discrepancy, temperature distribution, Struve-Sahade effect, and some kind of line profile variations. In summary, CoMBiSpeC is a first step in the spectral modelling of massive binary systems and several improvements are still needed to be able to study all massive binaries. Nevertheless, this model can explain and reproduce various observed phenomena which was the main goal of this thesis. [less ▲]

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See detailDiagnostic de sites et méthode d’implantation de tours pour une insertion urbaine de qualité
Saint-Pierre, Claire ULg

Doctoral thesis (2014)

The matter of towers construction in urban areas has been coming back among topical subjects, taking part in the questioning of sustainable urban development. While the debate still remains as regards ... [more ▼]

The matter of towers construction in urban areas has been coming back among topical subjects, taking part in the questioning of sustainable urban development. While the debate still remains as regards towers legitimacy, location choices are primarily driven by economic considerations (funding, real estate availability) and the issue of urban insertion is not always tackled at the right time. The decision-making process of tower construction is linear and takes into account some criteria relatively late even though if it was done earlier they could anticipate the impact of the tower on its urban environment. Using several comparative analysis (benchmarking), we identified the inherent criteria in this decision-making process. Their analysis and classification allowed us to highlight the preponderance of six criteria and the presence of significant interaction between them: the functionality, the shape, the movement, the public space, the environment and the townscape. The relations which exist between criteria reflect the complexity of the tower location process for which the most appropriate study approach seems to be the systemic. Between the multi-criteria analysis and the systemic approach, our implantation method of towers offers to consider these criteria at the very beginning of the project. Thus, it allows to draw up a list of indicators of urban integration which evaluation will indicate the quality of tower insertion in the urban environment. By considering upstream the identified criteria and also in a regular and diffuse way, the decision-making process of tower construction will be more efficient and effective to help finding the right location for a future tall building project. This implantation method is also designed to give rise discussions and reflections on the topics tackled, so that the dialogue between the actors turns towards a better location of towers in urban areas. [less ▲]

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See detailAs fronteiras de Nord-Pas-de-Calais: um estudo de campo sobre a securitização da imigração em França
Da Silva, Amanda Carolina ULg

Master's dissertation (2014)

This thesis aims to analyze the migration policies of France through the prism of the securitization of immigration theory. This theoretical current comes from the school of critical security studies, and ... [more ▼]

This thesis aims to analyze the migration policies of France through the prism of the securitization of immigration theory. This theoretical current comes from the school of critical security studies, and has as central concepts security threat, borders and boundaries. The securitization observes that immigration is conceptualized as a source of insecurity for the political community, where the boundaries are erected to protect autochthonous, where political speeches (anti-immigration) and migration policies (restrictive) are convergent. The french immigration and integration policies are guided by universalist republican model. The nature of this model provides a structural problem for implementing policies for minorities, that along with political speeches, against immigration, provided the increase in nationalism. There is a facility to convert the refugees into a source of insecurity due to the competition between human security and national security. The refugees are in the gray zone of migration policies, where the concept can be easily manipulated, and the criteria for granting refugee status may be contested. The field research on the situation of refugees in Nord-Pas-de-Calais demonstrates that the dialectic between the concepts of refugee, illegal immigrant and sans-papiers contributes for the permanence of insecurity and confinement of refugees between the borders, which France and United Kingdom are implicated. This research reveals an absence of welcome context (of the government), where refugees are at the mercy of the illegal immigration market and police violence [less ▲]

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See detailContribution à l'exploration de la structure des sols par microtomographie aux rayons X : vers une amélioration de la modélisation hydropédologique
Beckers, Eléonore ULg

Doctoral thesis (2014)

The aim of this thesis is to tend towards a better representation of soil water horizontal fluxes in hydropedological modelling. Tillage practices result in soil structural modifications which impact soil ... [more ▼]

The aim of this thesis is to tend towards a better representation of soil water horizontal fluxes in hydropedological modelling. Tillage practices result in soil structural modifications which impact soil hydrodynamic behaviour. This study takes place in this context, aiming to understand these modifications using X-ray microtomography (µCT), which allows a more fundamental analysis of soil. Indeed, this tool becomes a key in the field of soil science, giving a direct insight of the internal structure of soil. Besides, anisotropy studies are still rare as tiresome, and this work shows that the current hydrological models are anyway unable to represent it correctly: when it is taken into account, it rests on the hypothesis of a simple ratio between vertical and horizontal conductivity functions. First, microtomography is used supplementary to usual methods for the establishment of hydrodynamic functions near saturation. We showed that the retention curve designed with µCT information is more realistic since it leads to a better estimation of unsaturated hydraulic conductivity. However, these results could be doubtful depending on the different µCT acquisition or processing choices and hypothesis. Particularly, the thresholding step is crucial. Consequently, we propose a new global thresholding method based on the visible part of soil sample porosity. This method has been tested and validated in the context of the present study. This step allows us to use microtomography results to increase our knowledge of soil structure. A principal component analysis on soil pores structural parameters confirms that connectivity, specific surface, volume and radius are key factors for the differentiation of soil horizons texturally similar but structurally different. Our results show that structural parameters have to be taken into account to improve hydropedological modelling, especially if pores orientation is considered. We described thus the relevant parameters that can be obtained with µCT and which could help to better model water fluxes in soil while discussing the remaining limits and uncertainties, about upscaling issues notably. [less ▲]

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See detailExactitude du positionnement numérique des axes de ruissellement dans les bassins versants agricoles
Ouedraogo, Mohamar ULg

Doctoral thesis (2014)

Des études récentes menées en Belgique estiment les dommages causés par les inondations et les coulées boueuses entre 12,5 et 122 millions d’euros par an pour les infrastructures publiques, et entre 1,6 ... [more ▼]

Des études récentes menées en Belgique estiment les dommages causés par les inondations et les coulées boueuses entre 12,5 et 122 millions d’euros par an pour les infrastructures publiques, et entre 1,6 et 16,5 millions d’euros par an pour les habitations. La carte des zones à risque potentiel de ruissellement concentré est l’un des outils mis en place par la Wallonie pour lutter contre ces phénomènes de plus en plus fréquents. Cependant, la résolution (10 × 10 m) du MNT utilisé pour extraire les axes de ruissellement est trop faible pour prendre en compte les détails de la microtopographie (travail du sol, résidus de cultures, cultures…) des parcelles agricoles. De plus, elle ne tient pas compte des incertitudes inévitables, présentes dans les données altimétriques utilisées. L’objectif de cette thèse est d’envisager l’utilisation des nouvelles technologies d’acquisition des données altimétriques de haute densité (plusieurs points/m²), i.e., le scanner laser terrestre (TLS) et la photogrammétrie à partir d’un véhicule non piloté (VNP) pour créer un modèle numérique de terrain (MNT) de meilleure exactitude et de haute résolution spatiale (maille de dimensions ± 1 x 1 m). Cela permet de tenir compte de la variabilité altimétrique des parcelles agricoles, et d’analyser son impact sur le positionnement numérique des axes de ruissellement. Dans un premier temps, un TLS et un VNP à voilure fixe ont été utilisés pour acquérir des données altimétriques sur un bassin versant agricole de 12 ha. Deux logiciels photogrammétriques ont permis de générer le MNTPSC (Agisoft PhotoScan) et le MNTMCM (MicMac) ; tandis que des traitements statistiques ont été nécessaires pour supprimer les erreurs systématiques présentes dans les nuages de points obtenus au TLS avant de les fusionner pour générer le MNTTLS. La comparaison des MNT avec des points de contrôle (GCP) positionnés au récepteur GNSS (Global Navigation Satellite System) en mode RTK (Real Time Kinematic) a montré que le MNTTLS est le plus exact avec un RMSE (Root Mean Square Error) de 4,5 cm, suivi par le MNTMCM et le MNTPSC avec des RMSE valant respectivement 9,0 et 13,9 cm. Dans un second temps, la méthode de Monte Carlo a été utilisée pour générer à partir du MNTTLS, des MNT équiprobables. L’extraction des axes de ruissellement à partir des MNT équiprobables a permis de définir pour chaque maille du MNT, la probabilité d’appartenir à l’axe de ruissellement, et de définir une zone contenant l’axe de ruissellement extrait du MNTTLS avec une probabilité définie. Une telle zone peut être utilisée pour la mise en place de solutions telles que les bandes et les chenaux enherbés. La comparaison des algorithmes de suppressions des dépressions fermées d’une part, et des algorithmes d’extraction de la direction de l’eau d’autre part, a montré peu de différence au niveau de la probabilité d’appartenance des mailles à l’axe de ruissellement lorsque le MNT est de haute résolution spatiale (± 1 m). Enfin, les analyses statistiques ont montré que les altitudes des GCP utilisés dans la méthode de Monte Carlo sont influencées par l’état d’ameublissement et par la rugosité des sols des parcelles agricoles. Les études futures, e.g., à l’échelle de la Wallonie, devront prendre en compte l’impact de ces erreurs. [less ▲]

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See detailFrozen Moments. Archival Materialities and Database-Narratives in Chris Ware's 'Building Stories'
Crucifix, Benoît ULg

Master's dissertation (2014)

Building Stories (2012), le dernier ‘roman graphique’ de l’auteur nord-américain Chris Ware se compose non pas d’un livre, mais d’une multitude d’objets imprimés sous divers formats et réunis au sein ... [more ▼]

Building Stories (2012), le dernier ‘roman graphique’ de l’auteur nord-américain Chris Ware se compose non pas d’un livre, mais d’une multitude d’objets imprimés sous divers formats et réunis au sein d’une boîte en carton surdimensionnée. Le lecteur est invité à trouver son propre parcours à travers ces différents formats de bandes dessinée. Bien que chaque pièce est reliée aux autres par un univers diégétique partagé et une multitude de détails, assembler les pièces du puzzle se révèle être une tentative perpétuellement frustrée. L’expérimentation de la matérialité du format à laquelle Chris Ware se prête dans Building Stories est intiment lié à plusieurs développements dans le champ nord-américain de la bande dessinée, et dans le secteur culturel plus large. Alors que la publication en série est en train de disparaître, le roman graphique s’est imposé comme un nouveau format dominant et culturellement légitime. En réunissant dans une boîte des fragments prépubliés qui sont maintenus dans leurs formats d’origine, ainsi qu’en multipliant les allusions à l’histoire matérielle de la bande dessinée américaine par les types de format qu’il intègre, Ware récupère le potentiel de la sérialisation comme un mode discontinu de publication radical pour le temps présent. À l’ère du numérique, Building Stories est à la fois un hommage à l’industrie de l’imprimé, ainsi qu’une bande dessinée qui se prête à un format empruntant aux pratiques de lecture typiquement associées aux nouveaux médias. En effet, Ware explore la database comme un mode d’organisation narratif qui permet aux lecteurs de générer perpétuellement de nouveaux récits. [less ▲]

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See detailSur les quantifications équivariantes en supergéométrie de contact
Nibirantiza, Aboubacar ULg

Doctoral thesis (2014)

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See detailLe Comité permanent R dans sa relation avec le Parlement et certains acteurs du pouvoir exécutif : cohérence ou incohérence?
Stans, David ULg

Doctoral thesis (2014)

Il est possible d’envisager dans un Etat démocratique, bien que de manière un peu restrictive, que les deux grandes formes de contrôle traditionnelles opérées sur les services de renseignement (efficience ... [more ▼]

Il est possible d’envisager dans un Etat démocratique, bien que de manière un peu restrictive, que les deux grandes formes de contrôle traditionnelles opérées sur les services de renseignement (efficience et légalité) peuvent s’exercer, de manière très générale, suivant cinq axes différents : interne (hiérarchique), exécutif (tutelle ministérielle), externe (avec une composante parlementaire), judiciaire et médiatique/société civile. Chaque axe peut être composé ou se subdiviser en divers mécanismes qui agissent parfois dans une temporalité différente. Le recours à un Comité indépendant et externe tend à répondre aux dysfonctionnements des services (interne, coordination, rétention d’information, dépassement de compétences, etc.) et au manque de capacité tant pour le Parlement que pour l’Exécutif, de mettre en œuvre leurs prérogatives dans cette matière. Il est théorique admis que pour être véritablement démocratique, le contrôle de la gouvernance du renseignement doit comporter une composante parlementaire. C’est donc à ces acteurs que nous nous sommes intéressés. Le choix a été fait en Belgique de recourir à un organe externe chargé, dans sa mission générale, de surveiller le respect des Droits et Libertés des citoyens par les services et l’Ocam mais aussi leur efficience et coordination au profit et dans le respect des compétences de certains acteurs. L’objectif du Comité n’est donc pas de remplacer les autres acteurs. Ce contrôle doit, dans sa mission générale, permettre aux acteurs de jouer leur rôle (sans les remplacer) et conduire ainsi à la réalisation d’un véritable contrôle démocratique favorisant la responsabilité de la gouvernance du renseignement tout en respectant un équilibre indispensable secret et ouverture. Nous avons donc chercher à savoir si permettre l’intervention de certains acteurs de l’Exécutif dans un mécanisme indépendant et externe, d’une certaine manière rattaché au parlement est cohérent ou non ? [less ▲]

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See detailTowards a better understanding of time-lapse electrical resistivity properties associated to organic contaminants and bioremediation processes in the subsurface
Caterina, David ULg

Doctoral thesis (2014)

Management of contaminated sites represents a major problem for our society. Geophysical methods arise progressively as non-conventional techniques that should allow decreasing the uncertainty linked to ... [more ▼]

Management of contaminated sites represents a major problem for our society. Geophysical methods arise progressively as non-conventional techniques that should allow decreasing the uncertainty linked to the local nature of punctual drilling/sampling measurements classically used to identify, characterize and monitor such sites. However, the use of geophysics for this purpose is relatively recent and still requires an improvement of geophysical imaging and a better understanding of the impact of contaminants and remediation processes on measured properties to be fully effective. The main objective of this thesis was thus to improve our knowledge on these two aspects. In order to assess the reliability of geophysical imaging, and electrical resistivity tomography (ERT) in particular, we first compare quantitatively different image appraisal indicators. The latter are developed to detect artefacts, estimate depth of investigation, address parameters resolution and appraise ERT-derived geometry. Numerical benchmarks are created representing different geological situations in terms of heterogeneity and scale. On the basis of this comparison, we propose a methodology and guidelines to appraise both qualitatively and quantitatively field ERT images. We show the successful applications on real data coming from the contaminated sites we investigated. It notably allows us to exclude from our interpretation zones of the electrical images that are not considered as sufficiently reliable. To enhance electrical imaging, we investigate three different approaches to incorporate prior information into the ERT inverse problem, namely reference model, structural constraint and regularized geostatistical inversion that we notably apply on real data coming from two contaminated sites. The results are benchmarked against the standard smoothness constraint inversion. Results with real data show that adding prior information in the inversion process always lead to a modification of the solution at least in zones of low sensitivity (allowing notably to better image contaminant plumes at depth). However, the choice of the constraint to apply is highly dependent on the type and amount of information available. Therefore, we provide guidelines that should help the practitioner to include their prior information directly into the inversion process through an appropriate way. To understand the temporal geoelectrical signature of organic contaminants and bioremediation processes, we monitor a site contaminated with hydrocarbons and subjected to stimulated bioremediation. We first show that the most contaminated areas above the groundwater table level are associated to very low resistivities. We then show that during biostimulation (promoting aerobic degradation) and natural attenuation, observed resistivity variations (up to 140%) are mostly located in the saturated zone of the contaminated area. They follow a seasonal trend suggesting a temperature dependence not observed in an uncontaminated zone of the site. However, in the contaminated area, changes largely exceed the expected variations due only to the temperature. We therefore investigate systematically different hypotheses that may explain such changes. Among those hypotheses, we show that microbial activity is a factor that may potentially influence the electrical signature of a contaminated soil and may contribute to the observed resistivity changes. In order to further study the electrical response associated to bacterial activity during bioremediation processes, we monitor a tank experiment that contains soils contaminated with hydrocarbons subjected first to biostimulation and then to bioaugmentation (with an inoculum of Rhodococcus erythropolis T902.1). Whereas no particular electrical signature is observed during the biostimulation phase, we observe a correlation between the evolution of bulk resistivity changes and the specific oil-degrading flora after bioaugmentation that cannot be attributed to fluid resistivity changes. This suggests a direct impact of microbial growth/activity on electrical properties through the modification of surface and/or local electrolytic conduction mechanisms. These latter results open up new perspectives for future experiments that should involve spectral induced polarization measurements allowing a better discrimination between the two conduction mechanisms. [less ▲]

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See detailModélisation numérique de la localisation des déformations dans le béton avec un modèle de second gradient
Jouan, Gwendal ULg

Doctoral thesis (2014)

Cette thèse porte sur l’utilisation d’un modèle de second gradient pour les problèmes de localisation dans le béton. La localisation des déformations est un phénomène courant dans les solides qui ont subi ... [more ▼]

Cette thèse porte sur l’utilisation d’un modèle de second gradient pour les problèmes de localisation dans le béton. La localisation des déformations est un phénomène courant dans les solides qui ont subi des chargements importants et qui mène progressivement à la fissuration du milieu. D’un point de vue pratique, il importe de prévoir la possible occurrence de tels phénomènes et de simuler le comportement de la structure après son apparition (on parlera alors de comportement post-localisation). Pour modéliser de façon objective ce phénomène, le modèle dit de second gradient «local», cas particulier des milieux à microstructure, est ici appliqué à des structures en béton. Le comportement du modèle est étudié pour des essais représentatifs de telles structures (poutre en flexion, propagation de fissures en mode I). Certaines limitations du modèle dans le cas de localisations importantes des déformations sont mises en évidence et on propose la transition vers un modèle cohésif afin de décrire l’ensemble du processus de fissuration. Ce modèle cohésif et la transition depuis la description continue sont formulés et implémentés dans un code de calcul éléments finis. [less ▲]

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See detailContribution à l'étude épidémiologique d'Anaplasma phagocytophilum chez des cervidés et suidés sauvages en Région wallonne.
Nahayo, Adrien ULg

Doctoral thesis (2014)

Au cours des vingt dernières années, de nombreuses études ont souligné l’importance croissante des maladies vectorielles. Au sein des arthropodes, les tiques occupent la deuxième place, après les ... [more ▼]

Au cours des vingt dernières années, de nombreuses études ont souligné l’importance croissante des maladies vectorielles. Au sein des arthropodes, les tiques occupent la deuxième place, après les moustiques, en tant que vecteurs d’agents pathogènes. L’anaplasmose granulocytaire humaine est une zoonose transmise par des tiques et dont l’agent responsable est Anaplasma phagocytophilum, une bactérie intracellulaire obligée qui infecte essentiellement les granulocytes neutrophiles. L’anaplasmose granulocytaire est considérée comme une maladie émergente qui suscite l’intérêt du monde scientifique. Jusqu’à présent, de nombreuses études ont été réalisées aussi bien sur les tiques vectrices d’A. phagocytophilum que sur les différentes espèces animales considérées comme réservoirs. Mais il reste actuellement beaucoup d’inconnues quant aux multiples mammifères sauvages qui hébergent cette bactérie et qui pourraient être considérés comme réservoirs potentiels. Dans ce contexte, les objectifs généraux de cette thèse étaient de déterminer si A. phagocytophilum circule au sein des populations de cervidés sauvages (cerfs et chevreuils) présents dans la zone d’étude (Région wallonne), si ces espèces sont des réservoirs compétents pour A. phagocytophilum et enfin si ces espèces peuvent être utilisées comme sentinelles sanitaires pour la surveillance spécifique de l’anaplasmose granulocytaire humaine. En outre, vu les populations importantes de suidés sur l’ensemble de la région, l’espèce sanglier a été la troisième espèce cible incluse dans l’étude. Pour remplir ces objectifs, des prélèvements ciblés (sang et rate) ont été réalisés sur les espèces cibles dans le cadre du programme de surveillance active mis en œuvre par le réseau de surveillance décrit dans la première étude. En 2006 puis 2011 et 2012, 854 cervidés et 513 sangliers ont été prélevés au sein des 33 unités géographiques couvrant la zone d’étude. Les échantillons ont été identifiés en fonction de l’espèce, de l’âge, du sexe de l’animal ainsi que de la date et du lieu de prélèvement. Un test d’immunofluorescence indirecte a été réalisé sur sérum pour détecter les anticorps anti A. phagocytophilum et une PCR 16S (qui permet d’amplifier un fragment du gène qui code pour le RNA ribosomal 16S) a été mise en œuvre sur les échantillons spléniques. Une partie des amplicons obtenus a été séquencée. Les enquêtes menées en cervidés ont montré que la séroprévalence apparente globale, en 2006 et 2012, était respectivement de 95% et 88% pour l’espèce chevreuil et de 37% et 32% pour l’espèce cerf. Les résultats PCR ont révélé que 94% des cerfs (79 sur 84) et 81% de chevreuils (245 sur 300) étaient infectés par A. phagocytophilum et que les résultats positifs étaient uniformément répartis sur l’ensemble de la zone d’étude. Par contre, le taux d’infection des sangliers était très faible puisque moins de 1 % des rates étaient PCR positives. En conclusion, nous avons montré pour la première fois en Belgique qu’A. phagocytophilum circulait de manière endémique au sein des populations de cervidés sauvages vivant en Région wallonne. Deux enquêtes sérologiques ont fourni les premiers indices de présence de cette bactérie chez des cerfs et chevreuils. Les analyses PCR ont ensuite révélé que ces deux espèces étaient fortement infectées par A. phagocytophilum par opposition aux sangliers qui présentaient des taux d’infection très faibles. Sur l’ensemble des résultats PCR positifs, les 25 amplicons séquencés étaient identiques quelle que soit l’origine de l’espèce (cerf, chevreuil ou sanglier) et ils présentaient 100% de similitude avec 2 souches d’origine humaine et plusieurs souches d’origine animale. Des études supplémentaires, qui ciblent les gènes ankA et groESL, sont nécessaires pour déterminer si les variants d’A. phagocytophilum qui circulent en faune sauvage sont pathogènes pour l’homme. Le cas échéant, chevreuil et sanglier devraient être considérés comme espèces sentinelles sanitaires pour la surveillance spécifique de l’anaplasmose granulocytaire humaine. [less ▲]

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See detailQuels agritourismes pour les campagnes périurbaines ? Les cas de la Wallonie et du Grand-Duché de Luxembourg
Dubois, Charline ULg

Doctoral thesis (2014)

To cope with the economic uncertainties of the changes, transformations, and transitions affecting current European and world agriculture, many farmers are rethinking the purposes of their business and ... [more ▼]

To cope with the economic uncertainties of the changes, transformations, and transitions affecting current European and world agriculture, many farmers are rethinking the purposes of their business and are looking to diversify their activities. Taking advantage of certain assets related to their operation and of opportunities for tourism development in the region (such as availability of buildings, subsidies related to ecology and environment images), some of them have chosen agritourism, a tourist activity proposed by the farmer on his/her farm. The literature includes many studies on this topic, but there is no consensus on terminology, definitions, and concepts: they vary from one author to another and evolve over time. Having distinguished different agritourist typologies in which accommodation is a basic element, we have personally chosen to study agritourism defined as "all tourist and leisure activities and services present in a working farm". Wallonia and the Grand Duchy of Luxembourg, our geographical research areas, are neighbouring entities, with similar agriculture, and their tourist markets offer some similarities. Included in rural tourism, agritourism is nevertheless marginal compared to the overall tourist product offered. Some successes might suggest that agritourism could be the panacea against the crisis in agriculture. But is this always the case? Agritourism should be defined, localized, and differentiated. Working on these two periurban entities of Western Europe which are not yet discussed in the literature, we wanted to understand and to identify agritourist dynamics. We wanted to understand the geographic relationship between agritourism, periurban countryside, local resources, and agricultural and tourist specializations. We wanted to understand the logic of the emergence of tourism on a farm and the links between tourist and agricultural functions in a specific spatial context. Finally, we wanted to understand the integration of the motivations of different types of tourists and their reasons for visiting particular regional and local contexts. To do this, we analyse both the location and the agritourist geographical position in relation to the different markets. To meet the objectives, we conducted a comparative heuristic analysis of agritourism in both territories. We interviewed key organisational representatives (31 persons), we made field observations, documents comparisons... We conducted interviews with various Walloon and Luxembourg farmers (34 life histories) affording different agritourist practices that we synthesized by circumstantial geographical sketches. We conducted surveys with potential tourists (1148surveys) in seven Walloon and Luxembourg tourist spots. These steps and the statistical and cartographic processing based on the results allowed us to build a heuristic geographical model of the Walloon and Luxembourg agritourism. The experiences of farmers interviewed allowed us to understand the position of the agritourist system in its spatial context. Each of them develops opportunities and experience threats (economic, social, from heritage) in connection with the launch of the project, a true survival kit in some cases. It appears that agritourism is not always a panacea for farmers. On the farm, the tourist function comes after the agricultural one and is based on the latter, but the agricultural function also benefits from the tourist function because both activities are related. The emergence of tourism is an autonomous decision of the farmers who can be influenced by other actors, including authorities, but also by other factors such as the existence of a local demand or the regional real estate pressure. There is no particular profile of tourists visiting agritourism, but some features, including those of family, are more favourable to the experience of this type of tourism. Definitions and representations as well as the reasons and expectations differ depending on the characteristics of the interviewed tourists: urban or rural origin, level of experience. Three agritourist profiles were also highlighted: those seeking accommodation in a rural environment, those who think about accommodation linked to gastronomy, those who prefer accommodation that would be a comfortable basis from which to tour in a tourist area. The comparison between the experiences of farmers and the expectations of tourists shows that there is a risk of developing different organizational temporalities in the farm "open" to tourists as well as of favouring unbalanced images of agritourism, which could lead to a vision and a promotion of agriculture which does not correspond to its regional reality. By combining the different results and by linking the typology of the Walloon and Luxembourg agritourist products, the types of rural areas and the geographical components, it appears that agritourism should not only be analysed according to the environmental dimensions, but that the analysis must also take into account other factors such as accessibility, local communities, hospitality, rural development policies, the real estate market, the agricultural orientation of farm operations, as well as the degree of complementarity with tourist spots. We have demonstrated that agritourism, combining agriculture with tourism, is not developing, either everywhere, or in the same manner, and differs between different types of periurban countryside, depending on local resources. Moreover, agritourism is not always a solution for all countrysides, nor always a path for each farmer, nor always a perfect tourist destination for all tourists. However, even if strict regionalization of agritourism does not seem possible when we consider all the factors involved in the different regions, trends may emerge depending on agritourist types. There is thus a link between agritourism type and countryside type, which the heuristic model we propose should allow to improve in order to increase the convergence between the expectations of the different stakeholders. [less ▲]

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See detailPopulations of aphid natural enemies in agroecosystems, with special emphasis on the Multicoloured Asian Ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae)
Vandereycken, Axel ULg

Doctoral thesis (2014)

The international trade of goods and food can lead to the introduction of alien species in the importing countries. Even if in the most cases there is no negative impact induced by alien species, in some ... [more ▼]

The international trade of goods and food can lead to the introduction of alien species in the importing countries. Even if in the most cases there is no negative impact induced by alien species, in some cases the new imported species can spread out of control. These species can cause economical and ecological damages. The Multicoloured Asian ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is one of these species which was intentionally introduced for biological control and has spread from its native range in Central and Eastern Asia to large parts of North and South America, Europe and Africa. The decline of native species is linked to the spread and the aggressive behaviour of H. axyridis. The objective of this thesis is the evaluation of aphid's predator population densities and predator diversities, with a special focus on H. axyridis in agroecosystems in Wallonia, in the South of Belgium. First, field crops preferences of H. axyridis were determined. Later aphid's predator population changes during time were evaluated. Finally H. axyridis population changes between two crop farming were evaluated. Our main findings were as follows. Results, based on insects collected since 2001, highlighted that the first collected H. axyridis was in 2002 and the population of H. axyridis is increasing until 2008. In the same time population of Adalia bipunctata, Propylea quatuordecimpunctata and Psyllobora vigintiduopunctata, three native species, are decreasing. Samplings in agroecosystems highlighted that aphid's predator community is composed of few dominant species: three coccinellids Coccinella septempunctata, P. quatuordecimpunctata and H. axyridis, one syrphid Episyrphus balteatus and one chrysopid Chrysoperla carnea. We have shown that H. axyridis do not invade all Wallonia crops at the same rate because corn and broad bean are more invaded that wheat and potato at both larval and adult stages. Moreover in corn, H. axyridis populations has strongly increased from 2009 to 2011. Finally, organic farming do not enhance abundance of H. axyridis but lead to increase the total abundance of aphid natural enemies. [less ▲]

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See detailL'univers romanesque d'Hubert Juin : L'aventure d'une écriture
Kangomba, Lulamba ULg

Doctoral thesis (2014)

The work has as main purpose to study the work of romance Hubert Juin trying to illuminate the paradoxes it contains: regionalist themes whose treatment goes beyond codes of regionalism; writing practices ... [more ▼]

The work has as main purpose to study the work of romance Hubert Juin trying to illuminate the paradoxes it contains: regionalist themes whose treatment goes beyond codes of regionalism; writing practices near New Roman, without the texts claim to this literary movement. This analysis is closely related to the biographical and poetic texts of the author. The approach is characterized, first, by the work of literary pragmatics developed by Dominique Maingueneau; secondly, by the work on the space novel done by Jean Weisgerber. [less ▲]

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See detailRésonance locale et caractérisation de défauts de délaminage par vibrothermographie
Demy, Philippe ULg

Doctoral thesis (2014)

La vibrothermographie est une méthode de thermographie active utilisée en contrôle non destructif qui présente des caractéristiques intéressantes et peu communes pour la détection de défauts. Cependant ... [more ▼]

La vibrothermographie est une méthode de thermographie active utilisée en contrôle non destructif qui présente des caractéristiques intéressantes et peu communes pour la détection de défauts. Cependant, la méthode souffre d’un manque de fiabilité des résultats lié au chaos acoustique inhérent à la nature du contact pour la stimulation. La principale innovation de cette thèse consiste à étudier et proposer une méthode alternative à la vibrothermographie classique à partir d’un couplage linéaire obtenu par collage. La mise en évidence et l’étude d’un phénomène de résonance locale de délaminage a permis la mise au point d’une technique performante et fiable pour la détection et la caractérisation de défauts dans les matériaux composites. [less ▲]

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See detailL’HYPOGONADISME HYPOGONADOTROPE NORMOSMIQUE ISOLE (HHnI)
VALDES SOCIN, Hernan Gonzalo ULg

Master of advanced studies dissertation (2014)

L'hypogonadisme hypogonaodotrope isolé est une maladie génétique qui peut se produire avec un sens normal de l’olfaction ou en association avec une anosmie/hyposmie (syndrome de Kallmann.) L’hypogonadisme ... [more ▼]

L'hypogonadisme hypogonaodotrope isolé est une maladie génétique qui peut se produire avec un sens normal de l’olfaction ou en association avec une anosmie/hyposmie (syndrome de Kallmann.) L’hypogonadisme hypogonadotrophique peut aussi se décliner associé à d’autres traits distinctifs syndromiques, tel que le Prader Willy, que nous ne traiterons pas ici. Dans ce mémoire, nous nous concentrerons sur l’hypogonadisme hypogonadique central normosmique, qui d’un point de vue épidémiologique est plus fréquent chez l’homme. [less ▲]

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See detailEtude des propriétés de surface et techno-fonctionnelles des fractions protéose-peptones
Karamoko, Gaoussou ULg

Doctoral thesis (2014)

The total proteose-peptone fractions are complex heterogeneous mixture of thermoresistant proteins of whey. The general objective of this work was to contribute to a better knowledge and understanding of ... [more ▼]

The total proteose-peptone fractions are complex heterogeneous mixture of thermoresistant proteins of whey. The general objective of this work was to contribute to a better knowledge and understanding of surface properties and techno-functional properties (foaming and emulsifying properties) and well as setting a relationship between the different properties. In this work, PPT fractions were extracted according to a classical approach and other industrially transposable by considering respectively the skimmed UHT milk and whey protein concentrate (WPC) as raw materials. The using of such both sources allowed to highlight the fundamental differences in the composition of the extracts of PPT. This has begotten a direct impact on the surfactant properties of the PPT. It has been therefore established that these differences at interfaces can have major consequences on their techno-functional behavior. This study also made it possible to determine the contribution of components especially non-hydrophobic and hydrophobic fractions in the interfacial behavior of PPT and the influence of pH, protein concentration, source and method of extraction. The setting in relationship of properties showed the existence of some statistically significant correlations between the interfacial parameters and, foaming and emulsifying properties. It will be therefore possible to predict the behavior of techno-functional PPT from some physico-chemical parameters. Finally, this study also showed that PPT fractions can be used as techno-functional agents in various food formulations based foams or emulsions. [less ▲]

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See detailPopulation ecology of coastal bottlenose dolphins (Tursiops truncatus) in Northern Patagonia Argentina
Vermeulen, Els ULg

Doctoral thesis (2014)

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were ... [more ▼]

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were conducted in Bahía San Antonio, of which 227 were land-based and 129 were conducted from a small outboard-powered rigid-hull inflatable boat. In total, 1472 h was spend searching for dolphins, and resulted in 215 h of observation of 415 dolphin groups. Photo-identification data resulted in the identification of 67 individual dolphins. Based on mark-recapture analysis, total abundance had a maximum corrected estimate of 83 (95%CI = 46 - 152) individuals. Adult survival rates varied between 0.97 (SE = 0.04) and 0.99 (SE = 0.01). Average calving interval of the 14 reproducing females equalled 3.5 ± 1.0 years. This results in 3.5 births/year in the entire population and a minimum annual birth rate of 4.2%. However, data suggest that calves may have been born and lost before being documented, underestimating birth rate, calf mortality and possibly the number of reproductive females. Either way, the recruitment rate of calves appears to be insufficient to compensate the overall mortality in the population. Additional data further indicated the genetic isolation and extremely low genetic diversity within this community, thus indicating this community of bottlenose dolphins is highly vulnerable and at risk. Association patterns within the studied community were relatively strong (HWI 0.30 ± 0.08), re-indicating the small size of the population. Nonetheless, the fluctuation in prey density and availability appeared to be the most important factor determining their fission-fusion dynamics. It appears that a combination of aspects inherent to the species and this habitat, such as low cost of locomotion, low predation pressure and food predictability, has helped reduce the costs of fission in response to intraspecific competition. Behavioural data indicated that Bahía San Antonio is mainly used to rest and forage, with a marked diurnal and seasonal pattern in their activity. Furthermore, dolphins appeared to show a preference for the shallower waters inside their core area; they moved in and out with the tide to remain in the intertidal zone as much as possible. The observed variation in foraging activity and spatial distribution is suggested to be driven by a seasonal and locally predictable variation in prey density and availability. Most of the identified dolphins showed a yearlong residency and long term site-fidelity to Bahía San Antonio, suggesting it is the core area within the larger home range of this community. Furthermore, based on the frequent presence of calves and high residency of reproductive females, this protected coastal environment appears to provide shelter for nursing calves. Many individuals of this community ranged along the entire northern coastline of the San Matías Gulf, up to the Río Negro Estuary (approx. 200 km). Further to the north, in the southern part of the Province of Buenos Aires, a neighbouring community of bottlenose dolphins was shown to exist. Both communities are largely isolated from each other, and the environmental discontinuities between two adjacent oceanic regimes in which these communities live are hypothesised to promote their co-existence. Additionally, four individuals from another community, originating from the more southern Province of Chubut, are known to reside in Bahía San Antonio. These individuals are genetically differentiated from all other individuals in the area, clearly shown in their distinct morphology. The apparent fine-scale population structure of bottlenose dolphins over the relative small geographical distances in Argentina has conservation implications and indicates the need for further detailed research. Currently, the populations of bottlenose dolphins in the Provinces of Buenos Aires and Chubut are reported to have nearly vanished. However, this disappearance has been largely ignored in the past 40 years resulting in the studied communities to be one of the last ones remaining in the country. It seems that the coastal lifestyle and site-fidelity of coastal bottlenose dolphins, and the belief of the species to be common, may have obfuscated the need for more extensive research and conservation efforts in Argentina in former years. Local declines of common species are easily overlooked when establishing priorities for conservation, and Argentina is not a unique case. An ever-increasing number of coastal bottlenose dolphin populations are reported to be vulnerable or declining worldwide. This study provides insight into how the failure to recognise local population declines can threaten the regional status of a common species like the bottlenose dolphin. Continued research and urgent conservation measures are therefore strongly recommended to prevent the disappearance of the bottlenose dolphin from the coasts of this South American country. [less ▲]

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See detailClasses, conscience de classe et "classe politique"
Counet, Maxime ULg

Master's dissertation (2014)

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See detailEtude des racémases RacX et YlmE et de la protéine PBP4* de Bacillus subtilis en relation avec la désintégration de biofilms
Vanden Broeck, Arnaud ULg

Master's dissertation (2014)

Bacillus subtilis is a PGPR (Plant Growth Promoting Rhizobacterium) Gram positive bacterium and a model for studying the in vitro formation, maturation or disruption of biofilms. Biofilms have been ... [more ▼]

Bacillus subtilis is a PGPR (Plant Growth Promoting Rhizobacterium) Gram positive bacterium and a model for studying the in vitro formation, maturation or disruption of biofilms. Biofilms have been studied for many years because of their adverse effects in the medical sphere. Some D-amino acids have been reported among the factors playing a role in the disassembly of B. subtilis biofilms and a double ylmE and racX mutant (in which both YlmE and RacX racemases are absent) shows a delay in pellicle disruption [I. Kolodkin et al. Science (2010) 328:627-629]. The racX encoding gene is part of a bicistronic operon in which the first gene (pbpE) codes for a putative Penicillin-Binding Protein, the PBP4* whose function is not characterized. Results from DNA microarrays and Proteomics [D. Ren et al. Biotechnology and Bioengineering (2004) 86:344-364] have shown that in B. subtilis biofilms, the expression of the gene coding for PBP4* is increased. Our study in this master thesis aimed to investigate the functions and the structures of the RacX, YlmE and PBP4* proteins. A wide range of techniques such as cloning, into expression vectors, purification, treatment of the recombinant proteins by specific proteases to eliminate the chromatography affinity tags, structural and biochemical characterizations of the proteins have been used. According to sequence analyses, RacX belongs to the Asp/Glu racemase family. We succeeded to produce and purify 34 mg of RacX whose His-tag has been completely eliminated. The protein appeared active on D-Glutamate as substrate but inactive on D-Aspartate. A physiological role is proposed for RacX in the recovery of D-Glu from the peptidoglycan peptides. However, its implication in the biofilm disassembly process is still elusive. The YlmE racemase was also produced and purified (46 mg). Although a role in the in vivo production of D-Tyrosine in B. subtilis ageing biofilms has been proposed for this protein, our attempts to detect an activity on L-Tyr or any other amino acid remained unsuccessful. Bioinformatic studies relate YlmE to type III PLP dependent enzymes close to Alanine racemases. Alignments of YlmE with Alanine racemases pointed out that a C-terminal domain was missing in YlmE. A model has been proposed to explain the absence of YlmE activity. Several constructs were performed to restore a racemase activity: e.g. a fusion of YlmE to the C-terminal domain of the AlaR2 racemase from B. subtilis, but the chimeric protein was insoluble, or the fusion of the AlaR2 C-terminal domain to TrxA in view to obtain in trans complementation with purified YlmE. PBP4* (encoded by pbpE) has been purified (63 mg) and two activities were detected: L-aminopeptidase and DD-carboxypeptidase activities. This PBP is composed of two distinct domains : a N-Terminal catalytic domain related to the D-aminopeptidase from Ochrobactrum anthropic and a C-terminal one that has a lipocalin-like fold. This domain seems involved in the oligomerization of the protein. First attempts of X-Ray diffraction of the entire protein crystals did not give data with sufficient resolution. Therefore, each domain has been separately produced to determine the 3D structure of this unusual PBP. [less ▲]

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See detailEspaces de suites, dimension diamétrale, propriétés (DN) et (Omega)
Demeulenaere, Loïc ULg

Master's dissertation (2014)

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See detailPoéticas del fracaso en la narrativa de David Toscana
Scheffer, Aurélie ULg

Doctoral thesis (2014)

Jusqu'à ce jour, l’œuvre de David Toscana (Monterrey, 1961) n'a été abordée par la critique que timidement et de façon partielle. Parmi cette maigre littérature critique, il est intéressant de remarquer ... [more ▼]

Jusqu'à ce jour, l’œuvre de David Toscana (Monterrey, 1961) n'a été abordée par la critique que timidement et de façon partielle. Parmi cette maigre littérature critique, il est intéressant de remarquer la fréquence d’occurrence d'un mot en particulier: “échec” (fracaso). Cette thèse se propose d'examiner les différentes manifestations intratextuelles de l'échec (Bärtschi et Leuzinger) dans l’œuvre toscanienne, c'est-à-dire, les formes fictionnelles de l'échec. Nous avons choisi de diviser notre étude en deux chapitres principaux: personnages et espace. Dans le premier, nous mettons en relation la notion d'échec et les divers protagonistes qui peuplent l'univers toscanien et tentons de comprendre dans quelle mesure ces derniers peuvent recevoir le qualificatif de “ratés” (fracasados). Plus concrètement, cette observation des personnages principaux favorise la réflexion sur ce que David Freundenthal appelle échec interne, en d'autres termes, l'échec très personnel et subjectif que ressent et vit l'individu, frustré dans ses désirs, ses projets et ses tentatives. À notre étude de l'échec interne correspond une perspective d'analyse interne: dans un premier temps, nous privilégions une approche de l’œuvre essentiellement orientée vers le texte même, et par conséquent, volontairement détachée de son contexte. Si nous optons pour ce type d'approche, nous nous refusons cependant à nous limiter à une analyse strictement thématique. Ainsi, nous pensons l'échec tant d'un point de vue thématique qu'en fonction de ses manifestations dans le processus d'écriture, c'est-à-dire, à travers les techniques et structures narratives appliquées au texte littéraire. L’œuvre du narratologue français Gérard Genette intitulée Figures III nous sert d'appui théorique dans l'appréhension des formes narratives de l'échec. Le second chapitre met l'accent sur la relation entre échec et espace narratif. En réalité, tous les personnages de Toscana partagent un même espace, le Mexique. Selon nous, la représentation que l'auteur fait de cet espace est à son tour inséparable de la notion d'échec. Aux antipodes des “foundational fictions” (Sommer), l’œuvre met en scène une nation désunie, incapable de se définir, d'assumer le passer et d'aller vers l'avant, incapable de synthétiser ses divergences, de respecter ses traditions, de s'identifier à un profil de valeurs propre. Ainsi, par exemple, la famille et la religion apparaissent, sous la plume de Toscana, comme des valeurs stériles et insubstantielles. Cette approche ne renvoie donc plus à l'échec interne mais bien à l'échec diagnostiqué de l'extérieur ou échec externe, selon l'expression de Freundenthal: indirectement et avec subtilité, Toscana postule le non-aboutissement d'un projet, celui qui aspirait à la constitution d'une nation mexicaine forte et cohésive, orientée vers l'avenir. Ce second chapitre repose sur les principes majeurs de l'analyse du discours. Pratiquer l'analyse du discours suppose l'acceptation que chaque phrase porte en elle un message qui la dépasse et dont le sens est à chercher tant dans son contexte d'énonciation que d’interprétation. Rejetant l'opposition traditionnelle entre texte et contexte, entre un “intérieur” et un “extérieur”, l'analyse du discours littéraire privilégie une conception du texte comme maillon d'une longue chaîne appelée “interdiscours” et qui correspond à “l'ensemble des unités discursives avec lesquelles un discours particulier entre en relation implicite ou explicite” (Charaudeau et Maingueneau 2005: 334). Le texte littéraire est donc à considérer “relationnellement et historiquement” (Meizoz 2010: 66) puisqu'il s'inscrit toujours dans un processus de communication, dans un échange réel ou virtuel avec la parole d'autrui. Adoptant cette perspective, nous décidons de chercher et de créer du sens à travers la mise en relation du texte toscanien avec un certain discours sur la mexicanité. En fait, l'échec se manifeste selon nous à travers la présence d'une série d'images nationales stéréotypées que l'écrivain régiomontain récupère et manipule à sa guise dans l'ensemble de son œuvre. De ce jeu avec les stéréotypes découle la construction d'un imaginaire national déterminé traduisant, de manière implicite et symbolique, l'échec de la nation mexicaine. Ainsi, nous insistons notamment sur l’affinité entre la fiction toscanienne et le célèbre discours sur la mexicanité d'Octavio Paz, énoncé dans son essai Le labyrinthe de la solitude. Plus que de simples traces de banalité, ces stéréotypes qui envahissent l’œuvre de Toscana constituent à nos yeux de véritables éléments narratifs dotés d'une fonction constructive et productive propre. La théorie des stéréotypes, une des nombreuses théories littéraires qui se revendiquent de l'analyse du discours, constitue le cadre théorique principal de ce second chapitre. [less ▲]

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See detailBodies of Evidence: An Anthropology of the Health Claim
Hendrickx, Kim ULg

Doctoral thesis (2014)

How can a food or food ingredient be proven healthy, without calling it a drug? In this thesis, I make an attempt at understanding the stakes of a heated debate involving scientists from the food industry ... [more ▼]

How can a food or food ingredient be proven healthy, without calling it a drug? In this thesis, I make an attempt at understanding the stakes of a heated debate involving scientists from the food industry, academia, and the European regulatory authorities. The centrality and importance of 'science' in the debate is remarkable, and merits our full attention. The 'science' that is disputed between 'industry' and 'the regulatory authorities', and that serves as a vehicle for their credibility and authority respectively, consists of a very particular practice of putting molecules to the test in clinical trials. The clinical trial in drug testing allows for making a qualitative leap from a molecule's biological action to its therapeutic effect. In the case of food, it is not permitted to define the molecule's therapeutics in relation to pathology, otherwise the substance tips over and becomes a drug. The shared concern of all scientists involved in the debate is to avoid this 'tipping point'. What the debate shows, is not so much an opposition between 'corporate science' and 'regulatory science', but an uneasy relationship between the ecology of pharmaceutical drugs, and an ecology-yet-to-be-made for food therapeutics. Such an ecology rests upon a pattern of collaboration -or agencement- between materials and humans pertaining to different realms of production, regulation and science. As such, the terms of the debate on healthy food ingredients can be reformulated in more precise terms than 'industry' versus 'the authorities', or 'good science' versus 'bad science', which only come to exacerbate a deeper-lying tension that is technical and political at once. At stake are our conceptions of health and disease, cure and prevention, and the professionals that have the authority to talk about health in present-day Europe. [less ▲]

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See detailSequential decision making under uncertainty in randomly generated games : A Minecraft intelligent agent for resource gathering
Lorent, Pierre ULg

Master's dissertation (2014)

Video games have significantly evolved since the emergence of first arcade games. They have become more and more complex and now allow for the simulation of advanced environments. This work focuses on the ... [more ▼]

Video games have significantly evolved since the emergence of first arcade games. They have become more and more complex and now allow for the simulation of advanced environments. This work focuses on the development of an intelligent agent that aims at collecting a given type of ressource in random worlds from Minecraft, a well-known video game. [less ▲]

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See detailManagement of night-only electricity meters
Merciadri, Luca ULg

Master's dissertation (2014)

In this Master’s thesis, the influence of PhotoVoltaic (PV) panels on the distribution network is explained and related available solutions are also mentioned. We focus on a solution which consists of ... [more ▼]

In this Master’s thesis, the influence of PhotoVoltaic (PV) panels on the distribution network is explained and related available solutions are also mentioned. We focus on a solution which consists of optimally using flexible loads. We consider a price signal with two settings: off- peak tariff and on-peak tariff. Some suitable loads are connected to specific electricity meters, called ‘night-only meters,’ which allow the consumption of power only in off-peak periods. We describe the meters’ characteristics and the suitable loads. We also discuss the aspects related to the practical implementation. Historically, off-peak periods were located during the night and on-peak periods during the day. Changing the assignment of off-peak periods is an easy method for distribution system operators to access to the flexibility of small consumers. This solution can be implemented quickly as the infrastructure needed already exists. We propose a mixed-integer linear model to assign optimally the off-peak hours so as to maximize a social welfare. This welfare gathers together the cost of electricity, the financial losses due to energy curtailments of PV installations and the loads’ wellbeing. Our model considers automatic tripping of inverters and constraints of the electrical distribution networks. We target night-only meters, but an extension to dual-hourly meters is also presented. The results compare the application of the classical pattern against the optimal one for summer and winter days, the influence of the available variable power for a summer day, and the use of a monthly-optimal pattern against the classical one for a summer month. The new disposition of off-peak hours can reduce by 50% the PV energy curtailed in the summer, and can also help reducing the power flow going through the High-Voltage (HV)/Medium-Voltage (MV) transformer. The document ends by a cost analysis comparing the homes’ money gains in two main cases: classical pattern and monthly-optimal one, for a summer month. For each case, the Distribution System Operator (DSO) either refunds curtailments or not. Four different types of homes are considered: with or without night-only meters, with or without PV. This analysis allows to know rapidly who earns money and who looses money by getting plausible values of electricity bills. [less ▲]

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See detailÉtude du mouvement autorotatif des grues sous vent turbulent
Vanvinckenroye, Hélène ULg

Master's dissertation (2014)

This work aims to study the motion of tower cranes subjected to turbulent wind. Tower cranes are structures composed of a rigid mast and a rotating jig. The jig may exhibit autorotations that could lead ... [more ▼]

This work aims to study the motion of tower cranes subjected to turbulent wind. Tower cranes are structures composed of a rigid mast and a rotating jig. The jig may exhibit autorotations that could lead to partial or total collapse of the structure. The crane is modeled by a single degree-of-freedom oscillator assuming a perfectly rigid jig rotating around a fixed point representing the jig-mast connection. In case of a unidirectional and spatially uniform velocity field, the problem presents strong similarities with a vertically excited pendulum. Three models are developed. The first one focuses on the behavior of the jig under some simplified assumptions, as a unidirectional and spatially uniform velocity field. This model aims to understand the behavior of the crane with a limited number of parameters. Depending on the shape of the velocity field, the response of the structure is characterized by the variance of the angular position and velocity, the percentage of autorotations, etc. In case of a deterministic and periodic wind velocity, the stability of the jig is represented in the amplitude-frequency parameter space and instability lobes can be highlighted for characteristic frequencies of the sollicitation. The intermediate and complete models raise the assumptions of the first model and define a realistic wind field characterized by its power spectral density. The stochastic process is studied thanks to Monte Carlo simulations. [less ▲]

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See detailCellular regulation mechanisms : case study of up and down states in the Purkinje cell
Wehenkel, Marie ULg

Master's dissertation (2014)

In 1963, Hodgkin and Huxley obtained the Nobel Prize to have shown that the electrical activity of a neuron could be modelled by an electrical RC circuit containing non-linear conductances. This discovery ... [more ▼]

In 1963, Hodgkin and Huxley obtained the Nobel Prize to have shown that the electrical activity of a neuron could be modelled by an electrical RC circuit containing non-linear conductances. This discovery made it possible to reproduce the electrical behaviour of neurons with a level of detail that has steadily increased over the last fifty years as new quantitative knowledge became available about the specific ionic currents that regulate the activity of a given neuron. But models with too many details are often non-robust and too complex for analysis. As control engineers need simplified models for control design, experimental neurophysiologists are in need of models that are amenable to sensitivity and robustness analysis, beyond the mere simulation of a given neuronal behaviour recorded experimentally. The Purkinje cell has been studied for over hundred years because its large dendritic tree enables to recognize it easily with a microscope. This neuron exhibits a bistability between a stable hyperpolarized down-state and a stable depolarized spiking state. It is one of the first discovered neurons, however its electrical behaviour is not well understood so far. The principal question of the thesis is to model the electrophysiology of the Purkinje cell to advance the understanding of its regulation mechanisms. More particularly, the objective of the thesis is to explore recent work about the role of the calcium current in neuronal excitability as a possible mechanism underlying the bistability observed in the Purkinje cell. The electrical activity of the Purkinje cell is reproduced in this thesis thanks to a reduced physiological model which can be seen as an intermediate between a detailed model with dendritic compartments and an abstract model of bistability. This novel model is the main contribution of the thesis. Its main ingredients are on the one hand a fast sodium current and a slow potassium restorative current whose particular kinetics account for the up-state excitability, and on the other hand a slow regenerative calcium current and an ultraslow calcium-dependent potassium current for bistability. The proposed model suggests several implications. First, a complex compartmental model seems unnecessary to reproduce the electrophysiology of the cell, although the profuse dendrites are an important characteristic of the Purkinje neuron. Secondly, the Purkinje neuron appears to be regulated by the same mechanisms as other bistable neurons such as the thalamocortical (TC) or subthalamic nucleus (STN) neurons. Its behaviour depends on the same feedback mechanisms (a fast regenerative sodium current, a slow restorative potassium current and a slow regenerative calcium current), event though the temporal signature is markedly different because of the specific channel kinetics primarily of the slow potassium current. Finally this novel model makes the Purkinje cell modelling amenable to robustness and modulation studies, as recently shown for similar neurons. [less ▲]

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See detailModélisation hydromécanique de l'argile à Opalines: retour d'expérience sur le micro-tunnel HG-A
Bertrand, François ULg

Master's dissertation (2014)

L’énergie nucléaire procure 15% de l’électricité mondiale, c’est 22% dans les pays de l’OCDE et 36% en Suisse. Comme certains déchets nucléaires sont hautement radioactifs, il est nécessaire de les isoler ... [more ▼]

L’énergie nucléaire procure 15% de l’électricité mondiale, c’est 22% dans les pays de l’OCDE et 36% en Suisse. Comme certains déchets nucléaires sont hautement radioactifs, il est nécessaire de les isoler de la biosphère. Pour ce faire, la voie privilégiée est le stockage en couche géologique profonde. En Suisse, l’argile à Opalines est étudiée au laboratoire souterrain du Mont-Terri dans ce but. Les expériences menées au sein du laboratoire permettent d’étudier les caractéristiques de l’argile à Opalines. Il s’agit d’une roche très peu perméable dans laquelle les circulations d’eau sont très lentes, les déchets seraient donc confinés à long terme. Une question importante est la durée du confinement. Les expériences telles que celles menées au sein du micro-tunnel HG-A fournissent des données qui permettent de calibrer et valider les modèles numériques. Des simulations à très long terme sont alors envisageables grâce à ces modèles. La modélisation du micro-tunnel repose sur des modèles physiques et mathématiques présentés dans ce travail. Par définition, ils impliquent toujours une certaine simplification de la réalité. Ces modèles dépendent d’un certain nombre de paramètres dont les gammes de valeurs doivent être évaluées expérimentalement. Dans ce but, des essais de laboratoire sont modélisés et interprétés pour caractériser le comportement de l’argile à Opalines. En raison de l’anisotropie du matériau, différentes directions de chargement doivent être considérées lors de ces essais. La littérature scientifique est aussi consultée. Une fois le comportement de l’argile à Opalines caractérisé, l’excavation du micro-tunnel HGA est modélisée grâce au code de calcul éléments finis « Lagamine ». Cette modélisation est réalisée en deux dimensions en incorporant une à une les différents types d’anisotropie (contraintes in situ, paramètres mécaniques et hydrauliques) dans le modèle. L’influence de chacune de ces anisotropies peut ainsi être mise en évidence. Le modèle rassemblant toutes les anisotropies permet d’observer une surpression d’eau à la position d’un forage situé latéralement au tunnel. Ce pic de surpression est néanmoins sous-estimé par rapport aux données expérimentales. Une zone endommagée est alors introduite afin d’améliorer le modèle. Dans cette zone, la résistance est diminuée alors que la perméabilité est accrue suite à l’altération. Une calibration est ensuite effectuée pour proposer un set de paramètres permettant de suivre correctement les données expérimentales. Enfin, le modèle est testé avec les données provenant du gonflement d’un megapacker mis en place dans le tunnel plusieurs mois après l’excavation. Pour cette phase, le modèle s’écarte plus nettement des données que lors de la période utilisée pour la calibration. [less ▲]

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See detailGeneric image classification: random and convolutional approaches
Begon, Jean-Michel ULg

Master's dissertation (2014)

Supervised learning introduces genericity in the field of image classification, thus enabling fast progress in the domain. Genericity does not imply ease-of-use, however, and the best methods in term of ... [more ▼]

Supervised learning introduces genericity in the field of image classification, thus enabling fast progress in the domain. Genericity does not imply ease-of-use, however, and the best methods in term of accuracy, namely convolutional neural networks, suffer from its lack. In this master thesis, we propose an alternative approach relying on extremely randomized trees and random subwindow extraction combine with elements of the convolutional networks. We explore two modes of utilization of the forest: primarily a direct approach where the forest is the final classifier (ET-DIC) and to a lesser extent, a preprocessing step where the forest is used to build a visual dictionary but where the actual classification is undertaken by a support vector machine (ET-FL). We show that, in both modes, our scheme performs better than without using the convolutional network elements but we are not quite yet reaching their performances. The ET-DIC variant keeps more in the line of classification forest advantages but performs less well as far as accuracy is concerned. This is further highlighted by the remarkable stability of the ET-DIC mode. This stability accounts for the ease-of-use of the method but also prevents elaborated optimization. We were able to score an accuracy of 0.613 whereas the record for this mode without the convolutional network elements was of 0.5367. The ET-FL produces better results at the cost of a greater variability of accuracy due to the loss of the ability to favor the interesting filters and a greater overfitting, consequence of the loss of the ensemble smoothing effect. The accuracies range from 0.55 to 0.7431 depending on the choice of hyper-parameters. The computational cost of both methods is much greater than with a traditional forest, however. [less ▲]

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See detailrecherche de nouvelles potentialités des bacteries du genre Bacillus pour l'agriculture et l'agroalimentaire
Ait Kaki, Asma ULg

Doctoral thesis (2014)

L’exploration des échantillons en provenance de divers environnements de l’Est Algérien (du lac salé de Ain M’lila et de la rhizosphère d’une plante adjacente ; de l’eau de la source thermale d’Oued El ... [more ▼]

L’exploration des échantillons en provenance de divers environnements de l’Est Algérien (du lac salé de Ain M’lila et de la rhizosphère d’une plante adjacente ; de l’eau de la source thermale d’Oued El-Athmanya et du sol environnant ; de la rhizosphère de la plante Calendula officinalis, cultivée en serre à Setif) a abouti à l’obtention de 39 isolats de Bacillus et de Paenibacillus, dont 28 % sont sélectionnés pour leur capacité à inhiber la croissance de certaines moisissures phytopathogènes comme : Alternaria alternata, Aspergillus niger, Botrytis cinerea, Cladosporium cucumerinium, Fusarium oxysporium et Fusarium sp. Le calcul du taux d’inhibition de la croissance fongique par les isolats sélectionnés, réalisé, à titre d’exemple, sur F. oxysporium et B. cinerea, a permis d’obtenir des valeurs variant entre 39% et 84% suivant l’isolat. L’identification moléculaire des isolats sélectionnés par l’analyse d’ADN-16S et du gène « gyrase-A » a montré que les isolats de Ain M’lila appartiennent à Bacillus amyloliquefaciens, ceux isolés d’Oued El Athmanya sont : B. amyloliquefaciens, B. atrophaeus et B. mojavensis, enfin, les bactéries isolées de la rhizosphère de C. officinalis, sont : Paenibacillus polymyxa, B. velezensis, B. amyloliquefaciens et B. subtilis subsp. spizezenii. Les souches de Bacillus sélectionnées développent, dans les conditions de culture en fioles, des taux de sporulation importants variant entre 8 .108 et 27.108 spores/ml., alors que, le taux de sporulation chez P. polymyxa est insignifiant. Seuls les isolats de B. amyloliquefaciens sont capables de produire de la protéase. Cependant, l’activité cellulasique est observée chez toutes les espèces de Bacillus étudiées exceptant le B. atrophaeus qui a été le seul à produire de la chitinase. Toutes les espèces étudiées ont les mêmes capacités à produire les trois familles de lipopeptides (iturines, fengycines et surfactine), les siderophores et l’indole 3 acide acétique (IAA). Toutefois, le P. polymyxa (18SRTS) produit, dans les conditions expérimentales, une meilleure concentration d’IAA (54µg/ml). Par ailleurs, il est à mettre en exergue que, les B. amyloliquefaciens isolés du lac salé et de la source thermale produisent de nouvelles variantes de fengycines. En effet, il a été mis en évidence que le B. amyloliquefaciens (ET), produit de nouveaux homologues de fengycines A et B, ayant des chaines d’acides gras à 20 et à 18 atomes de carbone, respectivement, et deux nouvelles variantes de fengycines (fengycine X et Y) à cycles peptidiques dont la structure diffère de celle des fengycines conventionnelles. L’activité antifongique de certains isolats (B. amyloliquefaciens (ET), B. atrophaeus (6SEL), B. mojavensis (9SEL), B. amyloliquefaciens (9SRTS) et B. subtilis subsp. spizezenii (23SRTS)) sur milieux gélosés à base d’exsudats racinaires de tomate, de courgette et d’haricot, obtenus à différentes températures a été observée, vis-à-vis d’Alternaria alternata et de F. oxysporium. En complément, les souches B. atrophaeus (6SEL), B. amyloliquefaciens (9SRTS) et B. subtilis sub sp spizezenii (23SRTS), ont fait l’objet d’une production industrielle avec un taux de survie, après lyophilisation, très appréciable et leurs test in situ en serre et en champs sur le pois chiche a révélé une capacité intéressante de biofertilisation, de phytostimulation et de biocontrôle, ce qui justifie largement l’objectif assigné à cette recherche. [less ▲]

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See detailLa conditionnalité environnementale dans la politique agricole commune. Analyse de l'intégration de la politique de protection de l'environnement au sein de la politique agricole commune
Habran, Maxime ULg

Doctoral thesis (2014)

Pierre angulaire de la construction européenne, la politique agricole commune (PAC) est à l’origine mise en place dans le but d’assurer l’autosuffisance alimentaire de la Communauté européenne. L’objectif ... [more ▼]

Pierre angulaire de la construction européenne, la politique agricole commune (PAC) est à l’origine mise en place dans le but d’assurer l’autosuffisance alimentaire de la Communauté européenne. L’objectif, rapidement atteint, laisse dans son sillage des stocks et excédents considérables ainsi que des dépenses communautaires importantes. Le mode de production agricole basé sur un modèle productiviste montre rapidement ses limites, obligeant les Etats membres à une réorientation de la PAC. Cette politique sera modifiée et réformée à de nombreuses reprises. La reconnaissance de la protection de l’environnement comme politique transversale contraint les Etats membres à l’adapter. D’une politique productiviste, elle devient attentive aux considérations environnementales, intégrant ces dernières dans chacune des réformes, allant même jusqu’à lier l’octroi de paiement au respect de règles essentiellement environnementales. Cette recherche présente la manière dont s’articule la relation entre les deux politiques autour de la notion de conditionnalité environnementale. A travers une étude minutieuse de chaque réforme de la PAC, une analyse de transversalité permet de saisir les enjeux et les motivations de l’intégration environnementale. [less ▲]

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See detailAssessing tropical forage species used as pig feed ingredients in the western provinces of the Democratic Republic of the Congo
Kambashi Mutiaka, Bienvenu ULg

Doctoral thesis (2014)

The use of forage species to feed pig goes back to immemorial times. If forage is no longer used in industrial farms with genetically-improved breeds, its accounts for an important part of pig diets in ... [more ▼]

The use of forage species to feed pig goes back to immemorial times. If forage is no longer used in industrial farms with genetically-improved breeds, its accounts for an important part of pig diets in smallholder pig production systems in tropical areas including the Western provinces of the Democratic Republic of the Congo (DRC). The aim of this research thesis was to assess the relevancy of the use of local forage resources as a strategy to reduce reliance of pig production systems on concentrate feed ingredients in tropical environment, by identifying plant species available to smallholders with interesting nutritional value that could partly replace concentrates in the diets. First, smallholder pig production systems in two western provinces of the DRC were characterized and the most used forage species in pigs identified. Their nutritional value was determined using an in vitro model of the pig’s gastro-intestinal tract. It was concluded that Manihot esculenta, Ipomoea batatas, Moringa oleifera, and legume species exhibit an interesting profile for feeding pigs while grasses, Eichhornia crassipes, Acacia mangium and Cajanus cajan should be discouraged. Feeding values of Psophocarpus scandens, Vigna unguiculata, Stylosanthes guianensis, and Pueraria. phaseoloides were measured by assessing the voluntary feed intake of forage hays-based diets and their digestibility. Finally, the economic impact of feeding Psophocarpus scandens, Vigna unguiculata, and Stylosanthes guianensis, was measured through growth performance, carcass quality, and production costs determination. It is concluded that although forage species reduce the nutritive value and the growth of animals, the investigated legumes do not impact negatively the economical balance of concentrate-fed pigs when forage accounts for approx. 10 % of the diet. The ability of some forage species to improve performances of animals fed ill-balanced diets as usually practiced by smallholder farmers in the DRC should be investigated as it is suspected that under less favourable conditions, conclusions on the usefulness of forage legumes in pigs might be more positive [less ▲]

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See detailImprovement of data quality for Diffusion Kurtosis Imaging and application to clinical neurological research
André, Elodie ULg

Doctoral thesis (2014)

Understanding human brain function and dysfunction is one of the major challenges of our century. One of the most popular methods to achieve this goal is in vivo magnetic resonance imaging. In particular ... [more ▼]

Understanding human brain function and dysfunction is one of the major challenges of our century. One of the most popular methods to achieve this goal is in vivo magnetic resonance imaging. In particular, diffusion-weighted (DW) imaging has become a standard tool to non-invasively study white matter structure in vivo. The main contributions of this work can be divided in two parts. The first part deals with the development of pre-processing methods to improve image quality and the accuracy of diffusion tensor and diffusion kurtosis-derived parameters. First, we describe and evaluate a novel method to correct data misalignment due to subject motion. Using an iterative model-based approach, individual diffusion images are realigned to their own theoretical pair, rather than to the unweighted image. A recently developed advanced measure of tensor distance was used as a stopping criterion. The accuracy of the method is tested via a simulated diffusion tensor imaging data set. We have shown here that our procedure is a reliable and efficient way to correct subject motion during DW acquisitions, and that with a proper acquisition setup, it performs better than standard coregistration procedures. Next, we studied the influence of noise in diffusion kurtosis imaging. Two noise correction approaches are proposed and applied to a pool of 25 subjects to evaluate inter-subject variability and the impact of noise correction. Additionally, data were acquired on a single subject with different head positions within the coil and different acquisition scheme to evaluate the impact of noise correction on within-subject variability. Results show a strong impact of noise correction on the estimated mean kurtosis, while the estimation of fractional anisotropy and mean diffusivity were less affected. Both within- and between-subject signal-to-noise (SNR) related variability of the mean kurtosis estimate is considerably reduced after correction for the noise bias, leading to more accurate and reproducible measures. In this work, we have proposed a straightforward method that improves the accuracy of diffusion kurtosis metrics. Diffusion kurtosis imaging acquisitions at higher spatial resolution are made possible, which increases the chances to make valuable inferences in group analysis.The second part of this thesis deals with a clinical application of these methods. A large group of patients with early-stage Parkinson’s disease was investigated with diffusion kurtosis imaging and compared with a group of age- and sex-matched healthy volunteers using voxel-based analysis. Kurtosis metrics show more sensitivity to white matter changes than standard diffusion metrics. Significant differences were found in posterior cerebral areas as well as subcortical regions like the putamen, and are therefore promising results. [less ▲]

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See detailAnalyse et stratégies de développement de l’agriculture familiale dans un pays post-conflit: cas de la Province de Kirundo au nord du Burundi
Minani, Bonaventure ULg

Doctoral thesis (2014)

The Burundian family farming is indeed at the center of solutions to food and nutrition insecurity prevailing in Burundi. The agricultural sector contributes more than 40 % of GDP and employs 90 % of ... [more ▼]

The Burundian family farming is indeed at the center of solutions to food and nutrition insecurity prevailing in Burundi. The agricultural sector contributes more than 40 % of GDP and employs 90 % of active people. Kirundo famers practiced family agriculture market-oriented. This region was formerly considered as the breadbasket of the country because it fed many regions in cereals and legumes. Before 1993, Kirundo was the second rural province who had fewer households (28 %) living under poverty line. Today, this agriculture is consuming-oriented. Over 60 % of households in Kirundo Province live in food and nutrition insecurity, and 83 % of people live under poverty line. The objective of this study is to analyse underpinning constraints which hinder the system production performance of the region, in order to formulate strategies which can boost the family farming in Kirundo Province. In that case, a survey was carried out among 355 farm households in seven municipalities of the province. The results of this study showed that 282 farmers (79% of respondents) have small farmland and / or land conflicts as barriers to the family agriculture development. Contrariwise, the study identified also the existence of 73 farmers (21% of respondents) who didn’t have the small farmland and/ or land conflicts as constraints to the performance of their production systems. These farmers were divided into two groups: the first group (group A) included 41 farmers who were unable to fully exploit their land while the second group (group B) included 32 farmers who had a higher agricultural productivity. Thus, a case study was conducted with the farmers to know the core constraints which are impeding the land profitability in the first group (group A), and in other side, strategies implemented by other farmers in the group B to increase agricultural productivity. The results from this case study show that farmers partially exploiting their lands have an average area equivalent to 1.6 hectares per household, but only the third of this area is exploited. The crop yields (coffee, bananas, beans, maize, cassava, rice, sorghum, sweet potatoes, etc.) were lower than those observed at the national level. The main constraints of their lower production system performance are: the lack of agricultural workforce, this is lower because ( i) the rural exodus and early marriage of their children and departure of the household headers for seeking employment in Rwanda or in other family farms neighboring the regions, (ii) the lack of agricultural inputs, (iii) the lack of agricultural equipments, (iv) the use of moneylenders, (v) the insufficient erosion control techniques, (vi) the high rate of illiteracy,(vii) the poor distribution of organic manure between banana trees and other food crops, (viii) the persistence of traditional agro-pastoral techniques, (ix) the high animal mortality, (x) the low rate of households with fields in the lowlands and marshes, and (xi) the lack other opportunities outside the agricultural sector. Moreover, the strategies used by farmers with higher agricultural productivity for increasing the technical and economic performance of their production systems are: (i) the high rate of technology adoption (for erosion control, crop fertilization and pest management), (ii) the social development through the membership in local development associations well-structured and organized , (iii) the rational distribution of organic manure between banana trees and food crops , (iv) the application of modern agro- pastoral techniques, (v) the renewal of agricultural tools, (vi) the high rate of households with fields in the lowlands or marshes where they practice rice and other foods crops, (vii) the high literacy rate, (viii) the using of banks for credit, and (ix) the development of non-farm activities such as trade and crafts. The author concludes his study by recommending the development of non-farm activities, training farmers in modern agricultural techniques, the renewal of agricultural tools, the practices of food crops in the lowlands and marshes, and the development of small ruminants through the introduction of improved animal races and the practice of zero grazing as strategies to develop family farming in Kirundo Province. [less ▲]

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See detailComputation and approximation of the inverse of relationship matrices between genotyped animals: Algorithms and Applications
Faux, Pierre ULg

Doctoral thesis (2014)

The recent developments in molecular biology have made available thousands of genetic markers, allowing livestock genotyping at a reasonable cost and the subsequent development of genomic prediction. The ... [more ▼]

The recent developments in molecular biology have made available thousands of genetic markers, allowing livestock genotyping at a reasonable cost and the subsequent development of genomic prediction. The single-step procedure, a unified approach of genomic prediction, requires inversion of two matrices gathering additive relationships between genotyped animals: the genomic relationship matrix (G) and a part of the additive relationship matrix (A22). The inverse of A22 may also be interesting for other applications. Matrix inverse can be constructed successively by, first, computing, for each animal, the vector containing contributions of other animals to its relationship and, secondly, adding the product of each vector of contributions by itself to a zeroed matrix. The objectives of this thesis were (1) to propose algorithms to compute or to approximate the vector of contributions and (2) to test the numerical efficiency of these algorithms (computing speed, memory use and, if needed, approximation accuracy). Computing contributions covered two points: (1) finding or approximating which contributions are different from zero, and (2) computing the value of contributions considered as non-zero. In the first approach, we considered that animals closely related have non-zero contributions and approximated their values by linear regression. This approach was extended in a recursive way. In the second approach, we empirically determined the set of non-zero contributions by a heuristic algorithm of pedigree exploration (only for the case of A22). Values were then computed either by linear regression, or using the already computed inverse. We also tested an approximation strategy: limiting the number of extracted generations of non-genotyped ancestors to reduce pedigree complexity. In a third approach, we followed the same heuristic algorithm as before but restricted the pedigree exploration to find out which animals have a non-zero contribution. Their values were approximated by linear regression. The presentation of the different approaches is followed by a general discussion in which the approaches are compared. It was found that the best compromise between speed, memory and approximation accuracy was achieved by the last approach for the case of A22. Use of this last approach simplified computations and therefore made predictions more feasible. However, for the case of G, no sufficient approximations could be reach in a reasonable time. Perspectives of other uses of algorithms developed and of future researches were drawn, as well as practical perspectives for animal breeding. [less ▲]

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See detail"Je ne suis pas philosophe." Rousseau au miroir de l'épistolaire. Images de soi dans la correspondance de Jean-Jacques Rousseau (1730-1765)
Biquet, Stéphanie ULg

Doctoral thesis (2014)

L’objet de cette recherche consiste donc en une analyse de l’image de soi dans le discours épistolaire de Jean-Jacques Rousseau, depuis les premières années genevoises (vers 1730) jusqu’au départ pour ... [more ▼]

L’objet de cette recherche consiste donc en une analyse de l’image de soi dans le discours épistolaire de Jean-Jacques Rousseau, depuis les premières années genevoises (vers 1730) jusqu’au départ pour l’Angleterre (1765). Plus précisément, nous avons examiné le rapport que cette image entretient avec la figure du philosophe, qui fait l’objet d’une profonde reconfiguration au cours du XVIIIe siècle et qui nous semble une clé de lecture incontournable pour comprendre Rousseau. [less ▲]

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See detailMarcher en ville, percevoir et évaluer les ambiances. Etude de la "marchabilité" à Liège à travers deux cheminements.
Bastin, Florine ULg

Master's dissertation (2014)

A notre époque, où l'obésité touche une grande partie de la population et où le gaz à effet de serre ne cesse d'augmenter, la marche apparait comme une activité essentielle pour être en forme et pour ... [more ▼]

A notre époque, où l'obésité touche une grande partie de la population et où le gaz à effet de serre ne cesse d'augmenter, la marche apparait comme une activité essentielle pour être en forme et pour préserver l'environnement. Elle est devenue un réel enjeu pour le bien-être de notre société. Il est donc judicieux de comprendre quelles sont les issues pour bâtir une ville qui ferait marcher? Existe-il seulement une réponse? Dans ce travail de fin d'étude, je m'attache à comprendre le lien qui existe entre la forme urbaine et la pratique de la marche. Il s'agit plus précisément de saisir l'influence que peut avoir l'architecture sur la perception de l'espace. Pour répondre à cette problématique, j'ai réalisé une étude de terrain à Liège sur deux cheminements prédéfinis. j'ai pu évaluer le potentiel piétonnier de la ville de Liège, en employant une méthode qualitative d'approche sensible de l'espace par la marche et une méthode plus quantitative au moyen d'un audit de "marchabilité". Ce travail vise à promouvoir la marche en ville et invite à observer le paysage urbain avec une plus grande attention. [less ▲]

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See detailDensité et écologie des chimpanzés (Pan troglodytes schweinfurthii) dans le Parc National de la Kibira, Burundi
Hakizimana, Dismas ULg

Doctoral thesis (2014)

Les forêts tropicales africaines et les communautés de primates qu'elles abritent sont sérieusement menacées par l'accélération des taux de conversion et de dégradation des forêts ainsi que par les ... [more ▼]

Les forêts tropicales africaines et les communautés de primates qu'elles abritent sont sérieusement menacées par l'accélération des taux de conversion et de dégradation des forêts ainsi que par les activités de braconnage. L'impact de ces menaces est si grand que certaines communautés de primates ont complètement disparu avant d’avoir été reconnues, encore moins étudiées. Des données référentielles sont toujours nécessaires pour comprendre les variations spatio-temporelles des primates. Les estimations de la densité ou d'abondance des populations sont des outils de première importance lors de la détermination des priorités de conservation et de la mise en place d’un plan de gestion des populations de primate. Comme dans les écosystèmes forestiers, la répartition et l’abondance des différentes espèces d’arbres influencent profondément les communautés animales qui y vivent, nous avons d’abord cherché à déterminer la densité et la structure des espèces d’arbres de la forêt de Kibira. Dans 256 plots couvrant une superficie de 32,15 ha, un total de 6.504 arbres répartis en 70 espèces, 67 genres et 37 familles ont été enregistrés. La densité était de 202 tiges par hectare, avec une surface basale de 21,05 m² par hectare. Au total, six espèces de primates diurnes ont été enregistrées dont une espèce anthropoïde (Pan troglodytes schweinfurthii), quatre cercopithecinae (Cercopithecus mitis, Cercopithecus mona denti, Cercopithecus lhoesti et Lophocebus albigena) et une colobinae (Colobus angolensis). Seule la densité et l’effectif total de la population des chimpanzés sont connus, tandis que pour le reste des espèces, seul l’indice d’abondance kilométrique a été calculé. Cette recherche a accordé une attention particulière à l’espèce emblématique du Parc National de la Kibira, le chimpanzé d’Afrique de l’est, Pan troglodytes schweinfurthii. Afin de mieux protéger cette sous-espèce en danger d’extinction, nous avons mené des investigations sur les sites de nidification pour identifier les espèces et les caractéristiques des arbres sur lesquelles les chimpanzés comptent pour la construction des nids. Les résultats ont montré que les chimpanzés sélectionnent certaines espèces d’arbres lors de la construction des nids. Le secteur Mabayi, situé au nord du parc, est le plus riche en espèces de primates; il abrite cinq espèces sur les six enregistrées, et deux espèces: Cercopithecus lhoesti (menacée) et Colobus angolensis ne se retrouvent qu’à Mabayi uniquement. Cette partie du parc constitue une clé pour la diversité et devrait par conséquent bénéficier d’une attention particulière en matière de protection et conservation. [less ▲]

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See detailEffets génomiques et non-génomiques de l'oestradiol lors de l'activation du comportement sexuel mâle
Seredynski, Aurore ULg

Doctoral thesis (2014)

Testosterone, via its estrogenic metabolites, is involved in the control of different behaviors such as social communication or reproduction. Estrogens act mainly at the genomic level via the activation ... [more ▼]

Testosterone, via its estrogenic metabolites, is involved in the control of different behaviors such as social communication or reproduction. Estrogens act mainly at the genomic level via the activation of nuclear receptors to regulate the transcription of target genes but also act at the non- genomic level via the activation of membrane receptors. The main question of my work was how these two types of actions of estrogens interact to control male sexual behavior. [less ▲]

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See detailRole of transcription factor sox4b in the differentiation of pituitary cells in zebrafish.
Quiroz O' Donova, Yobhana ULg

Doctoral thesis (2014)

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and ... [more ▼]

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and terminal differentiation of specific cell types is still not fully understood. The SRY-like HMG-box (SOX) transcription factor Sox4 plays important roles in many developmental processes and has two homologs in zebrafish, Sox4a and Sox4b. We show that the sox4b gene is expressed in the pituitary anlagen starting at 24hpf and later in the entire head region including the pituitary. At 48hpf, sox4b mRNA colocalizes with that for thyroid stimulating hormone (tsh), glycoprotein subunit  (gsu) and the Zn finger transcription factor Gata2a. Loss of Sox4b function, using morpholino knock-down or expression of a dominant negative Sox4 mutant, leads to a drastic decrease in tsh and gsu expression and reduced levels of gh, while other anterior pituitary gland markers including prl, slβ, pomc and lim3 are not affected. Sox4b is also required for expression of gata2a in the pituitary. Knockdown of gata2a leads to decreased tsh and gsu expression at 48hpf, similar to sox4b morphants. Injection of gata2a mRNA into sox4b morphants rescued tsh and gsu expression in thyrotrope cells. Finally, sox4b or gata2a knockdown causes a significant decrease of gonadotropin expression (lhβ and fshβ) at 4dpf. In summary, our results indicate that Sox4b is expressed in zebrafish during pituitary development and plays a crucial role in the differentiation of thyrotrope and gonadotrope cells through induction of gata2a expression in the developing pituitary. [less ▲]

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See detailCourse à l'innovation et mécanique des brevets. L'évolution technologique dans l'industrie belge du zinc (1806-1873)
Peters, Arnaud ULg

Doctoral thesis (2014)

Dans le jeune État belge fragilisé par son statut international, l'innovation technique constitue une priorité étatique, mais aussi un des moteurs du développement entrepreneurial. L'essor industriel du ... [more ▼]

Dans le jeune État belge fragilisé par son statut international, l'innovation technique constitue une priorité étatique, mais aussi un des moteurs du développement entrepreneurial. L'essor industriel du 19e s. s'accompagne ainsi d'une course à l'innovation qui sous-tend de nombreux enjeux. Cette thèse les questionne en parcourant, dans un premier temps, le territoire codifié de la propriété industrielle. L'étude porte d'abord sur la construction d'un système belge des brevets. Comment est-il conçu par les premiers gouvernements belges ? Quelles sont ses caractéristiques ? Comment favorise-t-il la course à l'innovation ? Il convient d'appréhender d'abord les cadres juridiques, les références et les singularités qui définissent l'expérience belge. Ensuite, la nature de l'adhésion des acteurs au système est analysée. Dans un second temps, l'interrogation privilégie une approche sectorielle. La relation liant les brevets à l'innovation est examinée à travers le cas de l'industrie belge du zinc et de l'entreprise qui la domine : la s.a. des Mines et Fonderies de zinc de la Vieille-Montagne, première multinationale d'Europe. Que révèlent les brevets à propos des technologies en place et de leur évolution ? Par quels mécanismes contribuent-ils à l'innovation ? L'analyse porte sur un corpus de plus de 200 brevets étudiés à la lumière des archives d'entreprises. Elle éclaire sur les processus innovants et les conditions de leur déploiement. Cette histoire technique de la filière du zinc illustre les dynamiques qui s'attachent à l'innovation au temps de l'essor industriel. Elle met en lumière un ensemble de stratégies mises en œuvre par les industriels pour contourner les problèmes que pose la technologie en place : imperfection des méthodes de réduction, nuisances, mécanisation, diversification, etc. comme les tâtonnements, hésitations, échecs, ruptures inhérents aux processus innovants. [less ▲]

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See detailModes d'Organisation et Distribution de l'eau: Une Evaluation empirique de la Performance par les Méthodes des frontières de production
Mande Buafua, Patrick ULg

Doctoral thesis (2014)

Cette thèse est une contribution à l’analyse empirique de la performance (efficacité technique et effectivité) dans le secteur de la distribution de l’eau en Afrique Subsaharienne. Nous cherchons à ... [more ▼]

Cette thèse est une contribution à l’analyse empirique de la performance (efficacité technique et effectivité) dans le secteur de la distribution de l’eau en Afrique Subsaharienne. Nous cherchons à répondre à la question de l’impact des modes d’organisation (participation du secteur privé, régulation et une combinaison de deux) sur l’amélioration de la performance dans ce secteur. Notre analyse s’appuie sur les données issues de la base des données de l’AICD pour la période 2000 à 2005. Premièrement, grâce au modèle de Battese & Coelli (1995), nous calculons les scores d’efficacité technique et nous identifions les sources de l’inefficacité technique. L’approche PLP nous sert de technique complémentaire pour approfondir l’examen des élasticités d’échelle et du coût implicite des pertes d’eau sur le réseau pour chaque opérateur. En moyenne, les entreprises de l’échantillon sont techniquement inefficaces sur la période. Réguler par contrat de performance conduit à des scores d’efficacité technique plus élevés que réguler par agence. La participation du secteur privé dans la gestion ou l’exploitation du service présente un effet positif sur l’efficacité technique. Il n’y a pas de preuve d’une différence significative entre l’efficacité technique des entreprises sous gestion publique régulées par contrat de performance ou par agence de régulation et celles avec participation du secteur privé dans la gestion ou l’exploitation régulées par contrat de performance ou par agence de régulation. Les élasticités d’échelle sont, en moyenne, décroissantes. Le coût des pertes d’eau sur le réseau est évalué, en moyenne, à 4 travailleurs pour 100.000 m³ d’eau perdue. De plus, ce coût marginal a tendance à augmenter avec les niveaux de la qualité du réseau. Deuxièmement, nous analysons notre question de recherche en prenant en compte la performance en termes d’effectivité. Nous nous appuyons sur la méthode DEA basée sur la procédure en double bootstrap (Simar & Wilson, 2007) en appliquant l’approche analytique, en 4 étapes, inspirée de Mbuvi et al., (2012). Les résultats laissent entrevoir l’existence d’un problème d’ineffectivité plus élevé que celui d’inefficacité technique. Ainsi, les opérateurs ont besoin des ressources additionnelles pour atteindre 100% de leur effectivité. Réguler par contrat de performance conduit à une plus grande effectivité que réguler par agence de régulation. La variable relative à la participation du secteur privé dans la gestion ou l’exploitation du service a un effet négatif et significatif sur l’effectivité. Enfin, il n’y a pas de différence significative, en termes d’effectivité, entre les entreprises avec participation du secteur privé dans la gestion ou l’exploitation régulées par agence ou par contrat de performance et celles publiques régulées par agence ou par contrat de performance. Enfin, nous évaluons l’impact des variables institutionnelles sur les taux de couverture du service en utilisant les modèles à effets fixes. Nous nous attaquons à la question de l’endogénéité en utilisant le cadre proposé par Heckman (1978). Réguler par contrat de performance a un effet positif et significatif sur les taux de couverture. La participation du secteur privé dans la gestion ou l’exploitation du service possède un effet négatif et significatif sur les taux de couverture du service. Combiner la gestion publique avec la régulation par agence ou par contrat de performance conduit à des taux de couverture du service plus élevés que combiner la participation du secteur privé dans la gestion ou l’exploitation du service avec la régulation par agence ou par contrat de performance. [less ▲]

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See detailThe cyclic behaviour of sand, from the Prevost model to offshore geotechnics
Cerfontaine, Benjamin ULg

Doctoral thesis (2014)

The main objective of this thesis is the studying of the cyclic behaviour of dense sand. Its centre of gravity is the implementation of a convenient constitutive law in the finite element code LAGAMINE ... [more ▼]

The main objective of this thesis is the studying of the cyclic behaviour of dense sand. Its centre of gravity is the implementation of a convenient constitutive law in the finite element code LAGAMINE. The first step consists in summarising the salient features of the cyclic behaviour of sand observed in laboratory tests. Undrained monotonic and cyclic experiments are addressed. The phase transformation line is a key parameter in the description of its behaviour. The plasticity effects in both loading and unloading, the progressive pore pressure accumulation coupled with the degradation of the stiffness of the soil are of uttermost importance in the cyclic behaviour. The Prevost model is adopted for its conceptual simplicity and its physically related parameters. The basic equations of the model are described and its variants are illustrated. Calibration of the required parameters is carried out by means of simplified routines implemented in Matlab. A unique set of parameters is determined for each soil at a given relative density. Monotonic experiments are well reproduced. The model also replicates satisfactorily the trend of cyclic experiments. An implicit scheme is embraced in order to implement the model in the finite element code LAGAMINE. The implicit Prager translation rule is adopted for that purpose. It is ensured the discrete formulation reproduces exactly the analytical model. Accuracy, efficiency and robustness of the model are addressed throughout triaxial and multi-axial numerical examples. A hydro-mechanical interface finite element is developed. It consists in a three-node 1D isoparametric element. It is able to reproduce fluid flows across and along the interface. The unsticking of both walls of the interface is coupled with a suction effect due to the filling of the vacuum created. The behaviour of the element is illustrated by simple 1D examples of transient consolidation of a soil column. A final application consists in the modelling of a suction caisson, part of a tripod structure for wind turbines. An axisymmetric representation of this foundation is carried out. It is assumed embedded into dense Lund sand described by the Prevost model. Monotonic and cyclic simulations are performed in both drained and partially drained conditions. The salient features of the resistance of such foundations are highlighted. Their partially drained behaviour strongly increases their transient resistance. A storm including an extreme event is employed to simulate a cyclic loading. A pseudo-random short signal and its sinusoidal equivalent representation finally lead to an identical vertical settlement. This is confirmed by a long duration storm. Finally, a cyclic diagram summarising the final settlement attained for combinations of average and cyclic vertical loads is elaborated. Keywords [less ▲]

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See detailEtude numérique du comportement à long terme des déchets dans un centre d’enfouissement technique
Hubert, Julien ULg

Master's dissertation (2014)

L’explosion démographique des dernières décennies et la production gargantuesque de déchets accompagnant la consommation toujours croissante de la population font de la gestion des déchets un axe de ... [more ▼]

L’explosion démographique des dernières décennies et la production gargantuesque de déchets accompagnant la consommation toujours croissante de la population font de la gestion des déchets un axe de développement essentiel, pour lequel il reste encore beaucoup à faire. Les centres d’enfouissement technique (CET) font partie des alternatives disponibles afin de répondre à cette problématique. Il s’agit d’une solution peu élégante mais difficilement évitable pour des raisons économiques et parfois techniques ; le CET constitue l’outil de gestion privilégié dans les pays en voie de développement. Il ne faut pas croire pour autant que ce type d’ouvrage est délaissé dans nos régions. Bien que de plus de en plus de mesures soient prises afin de limiter les déchets pouvant être enfouis ou de favoriser le recyclage et la réutilisation de certains matériaux, l’enfouissement reste la solution la plus couramment appliquée. La gestion des centres d’enfouissement technique représente donc un pan important de la problématique des déchets. Le but de ce travail est de développer un modèle permettant de prédire les tassements à long terme dans les CET en tenant compte des différents phénomènes hydrauliques, mécaniques et biochimiques y prenant place. Les résultats d’un tel modèle permettraient, par exemple, de mieux évaluer la capacité de stockage des décharges rendant leur gestion plus simple et efficace. La première partie du travail consistera en une compilation des propriétés hydrauliques, thermiques, mécaniques et biochimiques des déchets présentes dans la littérature afin de référencer les paramètres nécessaires à la réalisation du modèle. Ensuite, une revue bibliographique des principaux modèles de comportement est présentée. Ce résumé permet de mieux appréhender les différents modèles existants et ceux sur lesquels nous nous baserons afin de réaliser nos simulations couplées. Finalement, la dernière partie du travail vise à réaliser le modèle de comportement multiphysique le plus complet. Ce dernier est construit étape par étape en commençant par l’implémentation d’un modèle hydraulique couplé, dans un second temps, à celui de transport d’Acide Gras Volatil (AGV). Les processus de génération/dégradation d’AGV et de production de chaleur sont ensuite introduits dans la simulation. Finalement, l’implémentation du modèle mécanique basé sur une loi de comportement mécanique de type CamClay est en mesure de prédire les tassements à long terme dans les centres d’enfouissement technique. [less ▲]

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See detailL'épidémie au cinéma : de l'infiniment grand à l'infiniment petit
De Re, Margaux ULg

Master's dissertation (2014)

« You know where this comes from, shaking hands? It was a way of showing a stranger you weren't carrying a weapon in the old days. » Contagion, Steven Soderbergh, 2011 For decades film directors, inspired ... [more ▼]

« You know where this comes from, shaking hands? It was a way of showing a stranger you weren't carrying a weapon in the old days. » Contagion, Steven Soderbergh, 2011 For decades film directors, inspired by numerous novelists, have exploited the epidemic in various ways: as a general historical context to tell another story (Isle of the Dead, Robson, 1945), as a medical topic at the heart of an investigation (Medical Investigation, Horwitch, 2004), or as a process allowing the proliferation of zombies (Resident Evil, Anderson, 2000) or even vampires (Daybreakers, Spierig, 2010). This work aims at theorising a fascinating and surprising topic – which goes as far as haunting public restrooms with the “Stop Germs: Wash Your Hands” signs – and to offer an overview of films that are very present on our screens and yet absent from scholarly works about cinema. By combining the analysis of photography with that of narrative, this research tries to address issues which may seem, at first sight, plain and transparent (showing the epidemic is showing contaminated individuals) but prove to be, in practice, much more complex (how can contamination be represented since this microscopic phenomenon is invisible to the eye?). The developed method leans on science and the ties between epidemic, contagion and contamination in order to establish an approach going from the more general (epidemic, which belongs to the global and is illustrated as far as the film’s synopsis) to the more particular (contamination, which falls under the interpersonal and is represented only in precise sequence of the film). Beyond questions about cinema or narrative in the strict sense, this final dissertation aims at exploring the other side of epidemic: the collective imaginary it creates. Indeed, the way cinema represents these phenomena indicates a certain conception of epidemic, which spreads from a film to the other, from a viewer to the other. [less ▲]

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See detailLe potentiel touristique du RAVeL en Wallonie
Evrard, Julien ULg

Master's dissertation (2014)

* Mise en évidence des rôles touristiques et de loisirs des voies vertes, et compréhension des attentes des utilisateurs quant à celles-ci. * Mise en évidence de tronçons RAVeL pouvant être supports ... [more ▼]

* Mise en évidence des rôles touristiques et de loisirs des voies vertes, et compréhension des attentes des utilisateurs quant à celles-ci. * Mise en évidence de tronçons RAVeL pouvant être supports d’activités touristiques par méthodes géomatiques. * Analyse de corrélations entre les fréquentations des RAVeL et ses caractéristiques environnementales : discussion. * Implication : poursuivre la stratégie de développement et la récolte de données statistiques. [less ▲]

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See detailIdentification des dommages aux portes de l'écluse de Havré : Canal du Centre
Pire, Timothée ULg

Master's dissertation (2014)

This work is about the identification of damage on sluices in Havré. A thorough study being already carried out on intermediate and downstream sluices, this report is about the upstream sluice. It is a ... [more ▼]

This work is about the identification of damage on sluices in Havré. A thorough study being already carried out on intermediate and downstream sluices, this report is about the upstream sluice. It is a miter gate on which several damage were noticed in 2004. Indeed, it shows some cracks, a door panel is twisted and some supports of knocker are worn. The origin of this damage is not found out yet. The goal of this work is so to determine the load cases that caused the listed damage. Therefore, the structure and the loads are modeled within the finite elements software Ansys. The analyse shows that, when the sluice is closed and withstands the hydrostatic pressure, the internal efforts are much lower than the resistance of the sluice. Contrariwise, stress peaks appear during opening and closing phases. Moreover, these peaks are located on weldings. A verification to fatigue shows that the life expectancy under normal maneuver loads is about 20 years while this sluice is being working for 40 years. The main load during the maneuvers is due the variation of water level either side of the sluice. This variation is taken equal to 10 cm in documents, but measures shows it can be greater. The twisting is certainly due to a blocking of the sluice during an opening and an oversizing of the cylinder. Eventually, the wear of knocker is due to maladjustment. Following this identification of damage, some proposition of reinforcement are proposed to increase the life expectancy up to 50 years. The modifications of the structure are related to the position of weldings, to sheet thickness, to the geometry of connections between cross rails and munions and to an increase of the steel grade. [less ▲]

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See detailFatigue Reliability of joint connections in support structure of offshore wind turbines
Mai, Anh Quang ULg

Master of advanced studies dissertation (2014)

This study is my initial attempt to investigate the evolution of fatigue reliability of welded joints in offshore wind turbine support structures. This information is crucial to update the inspected data ... [more ▼]

This study is my initial attempt to investigate the evolution of fatigue reliability of welded joints in offshore wind turbine support structures. This information is crucial to update the inspected data (crack sizes, probability of crack detection) to make the plan for the next inspection and maintenance of existing offshore structures in general. The thesis is limited to tracing back the fatigue reliability of welded joints from their design information. The later work for inspection planning will be continued in the framework of my Ph.D thesis. On the basis of the results of this research, it can be concluded that for the fatigue reliability problem, FORM and SORM gives results with high accuracy compared to MCS and that the design point found by FORM/SORM are really the global minimal reliability index. The assumption in dealing with cumulated damage shows a good agreement with MCS. This is the foundation for using a simplified LSF in reliability calculation of accumulative fatigue problem. [less ▲]

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See detailCaractéristiques Cliniques Et Impact Du Syndrome De Smith-Magenis : Étude d’une série de 47 patients
JACQUINET, Adeline ULg

Master's dissertation (2014)

Le syndrome de Smith-Magenis est un syndrome délétionnel récurrent caractérisé par l’association de traits dysmorphiques, de troubles du comportement et de troubles du sommeil. Une déficience ... [more ▼]

Le syndrome de Smith-Magenis est un syndrome délétionnel récurrent caractérisé par l’association de traits dysmorphiques, de troubles du comportement et de troubles du sommeil. Une déficience intellectuelle de sévérité variable est fréquente mais non systématique. Il implique une prise en charge médicale multidisciplinaire du fait des possibles malformations associées, essentiellement cardiaques et rénales, et des éventuelles complications (scoliose, problèmes ORL, anomalies ophtalmologiques, problèmes dentaires, métaboliques et endocriniens). Dans cette étude rétrospective, nous reprenons et discutons les caractéristiques cliniques et diagnostiques d’une cohorte de 47 patients ainsi que les répercussions du syndrome en termes d’impact familial, de prise en charge et de scolarité. [less ▲]

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See detailAnalyse de l'identité professionnelle des agents d'insertion du CPAS de Liège
Jacquet, Nicolas ULg

Master's dissertation (2014)

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See detailReprésentations de l’environnement et adoption des pratiques durables de production par les cotonculteurs du Bénin
Assogba, Sonagnon Claude-Gervais ULg

Doctoral thesis (2014)

The research aims at contributing to a better understanding of the adoption of eco-friendly innovations. It analyses representations of environment and practices associated with sustainable management of ... [more ▼]

The research aims at contributing to a better understanding of the adoption of eco-friendly innovations. It analyses representations of environment and practices associated with sustainable management of cotton farming systems in order to deepen understanding of logics and strategies underlining farmers’ practices, and motivations that determine their sustainable farming system adoption behaviors. Organic cotton (SCBIO) and cotton made in Africa (SCMIA) systems were used as case study. Field research was carried out in Kandi and Pehunco in the largest area of cotton production in the North of Benin. The theoretical framework is based on the theories of technical change analysis, the actor-oriented approach and the theories of social representations. Data were collected from a sample of 90 organic cotton farmers and 100 CmiA farmers selected from a typology based on endogenous criteria of prosperity. 39 field agents from organizations promoting sustainable cotton farming system were surveyed. Individuals and groups interviews were used to collect data. The data were analyzed with a combination of qualitative and quantitative methods including normative and relative comparison analysis, perception analysis, descriptive statistics, analysis of variance, chi square test, etc. Results show a marginal contribution of organic cotton and cotton made in Africa to national economy in comparison to the conventional system. At farmer’s level farming system analysis reveals that both organic cotton and cotton made in Africa systems are not intensively sustainable. Their implementation is characterized by a large gap between recommendations and farmers’ practices, especially in soils’ fertility and pests’ management. The use of organic matters in combination with crops rotation including leguminous plants is the main approach of soils fertility management in organic cotton system. However, quantities of organic matters used, especially cow dung, are not sufficient due to its low availability and the lack of transportation means. The management of pests and diseases faces enormous constraints ranging from biopesticides production difficulties, weak efficiency of biopesticides, to observation of the evolution of parasitic complex, etc. Although the use of organo-chemical fertilizer is recommended in SCMIA system, more than 50% of SCMIA farmers apply only chemical fertilizer. Globally, the quantities of chemical fertilizer applied are under the requirements while the quantities of organic fertilizers are too small. Application of staged and targeted pest control (lutte étagée ciblée) is limited by constraints coming from the late implementation and the ineffectiveness of pesticides, the high number of observations needed, etc. Therefore, pesticides are used in overdose and prohibited pesticides such as endosulfan are also used. Consequently yields are very low and decrease. In addition, some farmers, especially from organic system, considering necessity of chemical fertilizers use for maize production develop diverse strategic logics such as misappropriation, craftiness, etc. to obtain these fertilizers. It appears from analysis that strategic logics carried out by farmers in farming systems’ adoption are the result of a combination of explanatory factors. These factors contribute to deepen the understanding of the weaknesses of organic and CmiA values chains in Benin and the bottlenecks in their development. Far from being static, farmers’ logics area temporary equilibrium resulting from different explanatory categories relative to social representations of environment, perceptions of projects and production and social reproduction objectives of farmers, the demand of sustainable cotton on international market, etc. Consequently, all actions aimed at promoting the sustainability of cotton farming system may facilitate access of farmers to inputs through the improvement of their existence means for a better soil fertility and pests management. Sensitization and training programs on the importance of leguminous plants integration to crops rotation, staged and targeted pest control, etc., may be carried out. At policy level it would be desirable that policies decisions don't negatively affect the development of alternative cotton value chains. In addition, measures may be taken to facilitate farmers’ access to chemical fertilizers for food crops, especially maize, to avoid their selling off. [less ▲]

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See detailImpact of micro-physics and macro-physics on the seismic properties of main-sequence B-type stars
Salmon, Sébastien ULg

Doctoral thesis (2014)

L’étude des pulsations stellaires, tout comme les ondes sismiques sur Terre, nous donne une méthode puissante afin de découvrir l’intérieur des étoiles. Cette discipline scientifique est aussi connue sous ... [more ▼]

L’étude des pulsations stellaires, tout comme les ondes sismiques sur Terre, nous donne une méthode puissante afin de découvrir l’intérieur des étoiles. Cette discipline scientifique est aussi connue sous le nom d’astérosismologie. Grâce aux missions spatiales CoRoT et Kepler, l’astérosismologie est entrée depuis dans une période faste. Par ailleurs, une frac- tion significative des étoiles présente des pulsations, ce qui nous permet de sonder leur intérieur pour la plupart de leurs stades d’évolution. Cette thèse se concentre sur les étoiles de type B de la séquence principale. Via l’inter- action de leurs vents stellaires avec leur milieu environnant et la production de nouveaux éléments chimiques en leurs intérieurs, elles contribuent aux processus dynamiques et d’enrichissement chimique du milieu interstellaire. Heureusement, deux types de pulsa- tion stellaire affectent ces étoiles: d’une part les pulsations dites de type β Cephei et d’autre part celles de type SPB. La nature de ces pulsations est sensible aux processus physiques internes de ces étoiles. Ainsi, l’observation de ces pulsations nous offre de sonder ces différents processus. Dans cette thèse, nous étudions tout particulièrement la sensibilité de ces étoiles aux opacités ra- diatives, et nous appuyant sur ces résultats, contraignons l’opacité radiative des éléments du groupe du fer à l’aide des étoiles pulsantes repérées dans les Nuages de Magellan. Dans une seconde étape, nous évaluons la possibilité de contraindre la nature du mélan- ge (diffusif ou overshooting instantané) à l’aide de la modélisation des β Cephei par l’ap- proche directe. Nous testons également les facteurs influençant la détermination de l’exten- sion de la zone mélangée. Enfin, nous proposons un scénario explicatif de la récente découverte d’une nouvelle classe d’étoiles variables dans un amas stellaire connu pour comporter de nombreuses étoiles en rotation rapide. [less ▲]

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See detailSimulation d’une Cellule Solaire Cristalline par la Méthode des Différences Finies & Fabrication, Caractérisation et Modélisation de Cellules Solaires à base d’hétérojonctions organiques distribuées en volume
Aazou, Safae ULg

Doctoral thesis (2014)

This thesis is devoted to theoretical and experimental studies of the basic device of photovoltaic conversion : the solar cell. First, renewable energies are highlighted in a general introduction and ... [more ▼]

This thesis is devoted to theoretical and experimental studies of the basic device of photovoltaic conversion : the solar cell. First, renewable energies are highlighted in a general introduction and their economic, ecologic and environmental advan- tages in comparison with fossil energy resources are emphasized, then, a revue of structure, types of bonds and energy bands of a solid material is presented and the case of a semiconductor is considered. Starting from Maxwell equations, the basic semiconductor equations namely Poisson’s equation and the continuity equations of electrons and holes are established. Next, discretizations of Poisson’s equation using a finite difference scheme and of the continuity equations by the Gummel-Scharfetter scheme are performed. The obtained system of equations is solved iteratively according Newton-Raphson algorithm. The experimental part of the work, entirely achieved in LIOS affiliated to JKU at Linz (Austria), aims the fabrication and the characterization of organic bulk heterojunction solar cells based on two different polymers used as donors P3HT and AnE-PVstat and the molecule PCBM as acceptor. A comparative study of the fabricated solar cells indicates that the device efficiency depends on the donor:acceptor ratio. In or- der to understand electronic and optical mechanisms occurring within a solar cell and which may affect its characteristics and performance, and to identify the role of the equivalent circuit parameters describing these mechanisms, many electronic circuits modelling the solar cell are presented and only the five physical parameters circuit is chosen. Several physical parameters extraction methods are exposed in details and only three of them are retained to extract the five physical parameters of the fabricated solar cells. The effects of each physical parameter on the solar cell efficiency are investigated. Thus, the variation intervals of the photovoltaic metrics, fill factor and efficiency under the influence of parameters variations can be identified. [less ▲]

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