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See detailLe suffixe */-'ur-a/ : recherches sur la morphologie dérivationnelle du protoroman
Mertens, Bianca ULiege

Doctoral thesis (2018)

This thesis is dedicated to studying the Protoromance suffix */-'ur-a/ and, hence, to studying derivational morphology of Protoromance. On the one hand, we provide an extensive and detailed exam of ... [more ▼]

This thesis is dedicated to studying the Protoromance suffix */-'ur-a/ and, hence, to studying derivational morphology of Protoromance. On the one hand, we provide an extensive and detailed exam of Protoromance lexical units presenting the suffix */-'ur-a/ and, on the other hand, we produce a thorough analysis of the phonological, morphological and semantic properties of the suffix */-'ur-a/. The first part of this work consists of a short introduction and of the presentation of the methodology that we used in our research : the methodology of compared reconstruction and of internal reconstruction. Then, we focus on the two fields that are particularly interesting in the context of studying a Protoromance suffix : reconstruction in Romance studies and morphological reconstruction. This first part closes up with an explanation of our nomenclature – including a short analysis of the rejected words –, a specification of our research process and a presentation of the microstructure used for our etymological articles. In the second part of our thesis appear the etymological articles of all 45 Protoromance etymons with the suffix */-'ur-a/ that we were able to reconstruct. Each etymological article comes with a linguistic map that provides a global view of the geographical distribution of the concerned etymon. Finally, the third part of our work is a thorough and detailed analysis of the phonological, morphological and semantic properties of the Protoromance suffix */-'ur-a/ and of the diasystemic variation of the Protoromance language. [less ▲]

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See detailParents d'un enfant en rémission de cancer: Prédicteurs psychologiques et cognitifs de l'intolérance à l'incertitude dans le maintien des inquiétudes et dans l'orientation de l'attention sélective
Vander Haegen, Marie ULiege

Doctoral thesis (2017)

In spite of core medical advances realized these last years, the childhood cancer remains a distressing experience for the child and their parents. The cancer history is rarely linear and takes place into ... [more ▼]

In spite of core medical advances realized these last years, the childhood cancer remains a distressing experience for the child and their parents. The cancer history is rarely linear and takes place into a space and a particular time when marks are shaken. The stake in paediatric oncology is double: that the child is cured without side effects and that the child and parents cross this experience without psychological destabilization. When the cancer survivorship is diagnosed, new challenges are expecting for the child and parents. Indeed, the childhood cancer survivorship is considered as integrated into the field of chronic diseases where the factor of uncertainty coexists and requires continuous adjustments of the child and parents. Therefore, it is a period of progressive rehabilitation where the stake is double: control the relapse and treatments’ late effects (or aftereffects) of the child and allow the child and parents, “to pursue their life the most normally possible”. The survivorship experience is thus intense transforming deeply “the psyche” of the child and parents. Since a few years, empirical studies examine the child adjustment and parents in the course of treatments. These reveal namely some adaptation difficulties, anxious and depressive symptoms. However, the social/family support and the problem-focused coping seem positively moderate the distress intensity. Studies investigated the cancer survivorship were mainly centred on the child and showed its effects on the child’s psychological adjustment (e.g. anxiety, depression). Nevertheless, the distress intensity could be positively influenced in particular by social and family support factors. The thorough examination of the literature observes that studies rarely include the parent and that no study has associated the factor of uncertainty with the vulnerability factor of intolerance of uncertainty. The originality of this research lives in the interest centred on the concept of intolerance of uncertainty [IU] and its effects on the psychological and cognitive adjustment among parents of a child cancer survivor. This quasi-experimental, quantitative, longitudinal research combines standardized questionnaires (IUS, NPOQ, CAQ, Mini-CERTS, HADS, and WW-II), questionnaires created for the needs of the study (sociodemographic, QIPS-R15, OncoMed and SomaOnco) and two neuropsychological tasks (classic Stroop and emotional Stroop). The sample consists of 61 parents (45 mothers and 16 fathers) of a child cancer survivor (from 4 to 6 years of survivorship without relapse and with mainly a neoadjuvant chemotherapy during treatments). Three months later, parents returned to the laboratory and completed the same questionnaires and performed Stroop tasks (with the exception of words which are modified). The time was decided with medical teams. It seemed relevant to retest parents when the medical assessment of the child was completed in order to observe if the distress decreased. Besides, this time was sufficient to avoid memory biases. The first aim of this research is the study of parental distress. The proposed hypothesis is the existence of anxious, depressive, somatic symptoms and worries. Results showed that 70 % of parents had anxious symptoms (HADS), 39 % presented depressive symptoms (HADS), 14 % suffered from somatic symptoms (SomaOnco) and 70 % had worries (QIPS-R15). Results from moderation analyses indicated no main effect of gender, remission time, and couple on distress criteria (except the interaction of these three factors for worries). These results demonstrated the existence of a significant distress within the sample but also the presence of additional factors which may influence the parental adjustment. The second aim is the examination of IU and its maintaining factors (i.e. positive beliefs about worry, cognitive avoidance, negative attitude towards problems and repetitive thinking (ruminations)). The advanced hypothesis is the causal track between IU and its maintaining factors. Results of IUS questionnaire demonstrated on average that parents had a low tolerance of uncertainty (64 % of the sample) and that 60 % of the sample were located in a moderated to severe profile of generalized anxiety disorder (GAD). Concerning IU’s maintaining factors, results of NPOQ, CAQ, WW-II and Mini-CERTS questionnaires highlighted the existence of positive beliefs towards worry (WW-II: problem solving and positive trait of personality) and cognitive avoidance (CAQ: distraction and thought suppression). Results of regressions bear out the predictor status of IU for the development of its maintaining factors. Nevertheless, protective factors arose from analyses, particularly an effective problem orientation and the use of concrete experiential thinking mode (CET; Mini-CERTS), which could protect them from a deterioration of the mood (e.g. depression). These results indicated the negative influence of IU on the psychological adjustment, the protective effect of a positive attitude orientation and the use of CET among parents. The third aim concerns the study of cognitive processes in terms of orientation of selective attention and cognitive inhibition. The proposed hypothesis is the orientation of selective attention towards threat into the IU context. Results seem to indicate a longer latency for negative and coloured words during Stroop tasks. The within-group regression and mediation results reveal the mediating effect of IU between the orientation of selective attention towards threat and distress components (i.e. anxious, depressive, somatic symptoms and worries). Moreover, depressive symptoms contribute to predicting the coloured word latency (cognitive inhibition process). These results seem to demonstrate the negative influence of the IU on the orientation of selective attention and depressive symptoms for cognitive inhibition. Lastly, the fourth aim is the analysis of IU stability and its maintaining factors over time. The proposed hypothesis is the stability of IU and its maintaining factors because IU is considered as a feature of the personality. At the second assessment (n=51/N=61), three significant differences were observed. The first difference concerns a decrease for anxiety symptoms with nevertheless a score being located in the pathological border. The second difference relates to a decrease for the cognitive avoidance with a score situated in the superior border of the standards. Lastly, an increase for somatic symptoms level was observed at the second assessment. Concerning IU, results indicate no significant change. Parents who presented a high level of IU at the first assessment kept it at the second assessment. This observation is also true for parents who had a low level of IU. These results supported the hypothesis of IU stability and its maintaining factors over time. Overall, results emphasize the implication of IU in the psychological distress among parents and its effect on cognitive processes of the orientation of selective attention towards threatening words (negative words). This research brings out the necessity to identify parents who are at risk for IU (and its maintaining factors) at an early stage of the cancer management in order to avoid excessive worries and the use of dysfunctional strategies over time. Furthermore, this research allows future clinical avenues for the development of follow-up tools in paediatric oncology, and recommends the parents’ psychological adjustment follow-up in close collaboration with medical teams. Implications of this research are discussed into the "general discussion" part of the thesis. [less ▲]

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See detailDetermining astrophysical parameters of quasars within the Gaia mission
Delchambre, Ludovic ULiege

Doctoral thesis (2017)

Quasars are one of the most peculiar types of objects in astronomy. The supermassive black hole these harbour effectively makes the surrounding matter radiates an enormous amount of energy before getting ... [more ▼]

Quasars are one of the most peculiar types of objects in astronomy. The supermassive black hole these harbour effectively makes the surrounding matter radiates an enormous amount of energy before getting in the vicinity of the black hole horizon out of which it will never escape. This ironically leads to the most luminous phenomenon in the Universe while being non-transient. It is hence quite natural to rely on these cosmic headlights, visible up to ages when the Universe was still very young, so as to achieve some of the currently most important cosmological applications, notably regarding the determination of the cosmological parameters $H_0$, $\Omega_\Lambda$ and $\Omega_m$. The Gaia mission, on its side, is one of a kind given the one billion of celestial objects it is intended to observe, among which more than half a million quasars are expected. Furthermore, owing to its exceptional astrometric precision, Gaia stands out to be extremely well suited for the detection of gravitational lens (GL) systems. In the latter, light rays coming from a distant background quasar are deflected by the presence of a massive galaxy being in the line-of-sight that leads to the production of multiple images of this background quasar upon a favourable alignment between the quasar, the galaxy and the observer. Supplemental constraints on the aforementioned cosmological parameters being then gained based on these GLs. Gaia hence provides an unprecedented opportunity to detect and characterize quasars as well as to identify GLs which ultimately bring a better understanding of the Universe we live in. This thesis is accordingly concerned with the development of software solutions dedicated to the determination of the astrophysical parameters (APs) of the quasars that Gaia will observe, on one hand, and to the recognition of the GLs among the billion of sources it will uncover, on the other hand. Although Gaia provides state-of-the-art astrometric and photometric observations, its capability in characterizing these celestial objects remains however restricted by the relatively low spectral resolution of the blue and red spectrophotometers upon which it is based as well as by the limited signal-to-noise ratio that is associated with faint objects, including quasars. In addition, the overwhelming amount of data that Gaia has to process translates into a stringent need for algorithms having both low numerical complexities as well as low memory usages. These restrictions and shortcomings along with the requirement for reliable APs were at the heart of this research that led to the development of two specifically designed methods that are the weighted principal components analysis and the weighted phase correlation method. The former of these methods allowed us to extract the most significant patterns out of quasars with a view of using these in the production of a spectral library of quasars as observed by Gaia. These were subsequently used in a fast and automated procedure designed to guess the redshift of the quasars within the Gaia mission through the latter mentioned method. Other APs that are the slope of the quasar continua, the total equivalent width of their emission lines and whether these encompass broad absorption lines or not, being then concurrently derived based on the results of these methods. Finally, the identification of GL candidates relies on the recognition of the structures and symmetries that are observed within lensed images through supervised learning methods. The specific method we choose to use, based on extremely randomized trees, was shown to yield a low contamination rate on simulated configurations composed of three images as well as a very high probability of detection in cases of four image configurations. Real observations out of the first Gaia data release were processed and resulted in the identification of candidates having three potentially lensed images which are currently waiting for confirmation using ground-based facilities. [less ▲]

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See detailInfluence d'une prise en charge posturale sur la position assise, les capacités cognitives, le comportement et le bien-être de l'enfant en classe
Fettweis, Tatiana ULiege

Doctoral thesis (2017)

Cette thèse analyse l’impact d’une prise en charge posturale associée à l’utilisation d’un coussin triangulaire dynamique sur la position assise, les capacités cognitives, la concentration et le bien-être ... [more ▼]

Cette thèse analyse l’impact d’une prise en charge posturale associée à l’utilisation d’un coussin triangulaire dynamique sur la position assise, les capacités cognitives, la concentration et le bien-être de l’enfant en début d'école primaire. Elle comporte 4 sections principales. La revue de la littérature présentée dans la première section souligne le rôle de l’école et plus spécifiquement l’impact du mobilier scolaire sur la santé et les apprentissages des élèves. La deuxième section consiste à mettre en place et à étudier les qualités métrologiques d’une batterie de tests permettant d’évaluer la qualité de la position assise, les capacités posturales, le comportement en classe et les capacités cognitives d’enfants du premier cycle du primaire. La troisième section comprend trois études de terrain évaluant l’influence de la prise en charge en milieu scolaire. La partie principale consiste en un suivi longitudinal réalisé au cours des deux premières années primaires. Dans ce cadre, le cousin dynamique a amélioré la qualité de la position assise, les plaintes musculo-squelettiques, les capacités cognitives et le comportement des enfants en classe. Une première étude complémentaire a mis en évidence le caractère instantané de l’effet de la prise en charge et une seconde a confirmé l’impact positif du coussin dans une population présentant des troubles de l’attention. Enfin, la quatrième section comporte deux études réalisées au sein du Laboratoire d’Analyse du Mouvement Humain : une analyse biomécanique de la position assise a précisé l’effet positif et immédiat du coussin dynamique et une évaluation du contrôle moteur lombaire a démontré une meilleure proprioception lombaire chez les enfants habitués à utiliser le coussin. En conclusion, bien que cette recherche ne porte que sur une partie des facteurs entrant en ligne de compte pour le bien-être des élèves en classe ainsi que pour leur réussite scolaire, les différentes analyses et perspectives développées tout au long de cette thèse suggèrent la pertinence d’un coussin dynamique dans la mise en place de campagnes posturales préventives. [less ▲]

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See detailLa spatialité de la gouvernance des régions urbaines intermédiaires en Europe
Breuer, Christophe ULiege

Doctoral thesis (2017)

The governance of urban regions is a central research topic of urban sciences, and a major challenge for urban actors. In this research, we contribute to the analysis of governance processes by studying ... [more ▼]

The governance of urban regions is a central research topic of urban sciences, and a major challenge for urban actors. In this research, we contribute to the analysis of governance processes by studying the transformation of its spatiality in intermediate European urban regions. Our research postulates the intrinsically spatial nature of urban governance, and is based on three hypotheses: (1) the territorial characteristics of urban regions relate to local politico-administrative fragmentation, (2) the characteristics of politico-administrative fragmentation relate to the construction of a governance scale for urban regions, and (3) governance structures at the level of urban regions relate to territorial characteristics. In order to test these hypotheses, we conducted a research in three complementary parts. The first part is devolted to the state of the art on governance, territorial rescaling and institutional change. The second part analyses quantitatively the politico-administrative fragmentation of 123 intermediate European urban regions, and its links with territorial indicators. The third part analyses qualitatively the processes of transformation of spatial governance in the urban regions of Saint-Étienne (France), Metz (France), Sheffield (United Kingdom) and Liège (Belgium). This complementary research confirms the existence of links between the different aspects of spatiality in the governance of intermediate urban regions in Europe, and concludes that the recomposition processes are intrinsically spatial, territorial and multiscalar. [less ▲]

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See detailContribution à l'enseignement de la traduction au Niger : le renforcement du français langue cible dans la formation des futurs traducteurs.
Amadou Gazali, Alkassoum ULiege

Doctoral thesis (2017)

Teaching translation is a very old activity. While it often used to be performed in the context of language learning, it has changed fundamentally over the past few decades, i.e. since the ... [more ▼]

Teaching translation is a very old activity. While it often used to be performed in the context of language learning, it has changed fundamentally over the past few decades, i.e. since the institutionalization of translation as an autonomous scientific discipline with specific objects and methods. Now, it covers not only linguistics but also other fields including the operating aspect of knowledge and has undergone more methodological transformations over half a century than it did since the Middle-Age, or even since Cicero. In Niger, however, the situation has not yet changed. Teaching translation has remained part of language learning. In this context, the learners’ translation competence is directly associated to linguistic competence. But the latter is far from satisfactory for quite a lot of Niger students, whatever their field of study. In fact, several studies confirmed the poor performance of Niger students in relation to mastery of their working language, French. Indeed, despite its exclusive status as the language of administration and education, French is not mastered enough to be used as a basis for the learning of another language and even less for translation purposes. This is why this study is based on the hypothesis according to which improving the target language in translator training would largely contribute to upgrade their translation competence. It therefore aims to enhance Niger prospective translators’ translation competence by improving their knowledge of the working language. To this end, an experimental research method is used that relies on a classical type scheme involving pre- and post-experimentation observations. An experimental treatment is applied between the two observation stages, which consists of language remedial courses. The verification of the hypothesis depends on operational aspects of the study as well as on the results yielded by the interpreting of collected data. [less ▲]

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See detailBovine brucellosis in Argentina: current situation and intraherd simulation model
Aznar, Maria Natalia ULiege

Doctoral thesis (2017)

Bovine brucellosis is an infectious disease, which can negatively affect cattle productivity and human health. It is endemic in Argentina, where 0.8% of cattle and 12% of farms are infected, having this ... [more ▼]

Bovine brucellosis is an infectious disease, which can negatively affect cattle productivity and human health. It is endemic in Argentina, where 0.8% of cattle and 12% of farms are infected, having this percentages remained stable throughout the years. This thesis studies the disease in the country. At first a review on the Argentine situation is presented, which leads to two remarkable aspects: brucellosis remains endemic and it is not possible to reach its eradication. In order to to clarify those points, four main studies were performed. The study 1 is an analysis of cattle movement that showed that there are some districts potential spreaders of the disease while others have more at risk of introduction. The study 2 constitutes an estimation of the brucellosis prevalence and identification of the risk factors associated with an increased occurrence, which helps to improve the knowledge of the epidemiology of the disease in the country. When assessing the situation at the provinces under study, a spatial cluster of infected farms was detected. In that region, farms are considerably large, having lowanimal densities and few movements. Those factors probably correlate with infrequent veterinary control and poor sanitary conditions of the herds. Special attention should be paid to those zones sharing these characteristics since there is high chance of finding clusters of the disease. In the study 3 a method for evaluating some farmers' and veterinarians' management practices in relation to brucellosis and for assessing the vaccination campaign and coverage is developed. It shows that the vaccination campaign is globally well implemented, but the immunization coverage and some management practices should be improved. Finally, the study 4 develops an intra herd simulation model. Its aim is to predict the effects of the disease and to test different control and eradication strategies in different situations. As brucellosis is a contagious disease, when introducing one infected animal in a free herd, it might become endemic. In the case of endemic farms that do not eliminate the reactors, all the tested vaccination strategies produce a reduction in the disease outputs (abortions, infectious deliveries, new infected and born infected) whereas when no vaccination is applied, the outputs remain stable. The isolation of heifers from the general herd reduces the disease outputs by a half. Despite it, if the reactors are not eliminated the sources of infection are kept in the herd. Therefore, a strategy of elimination of infected animals has to be applied. Independently from the chosen vaccination strategy, applying serological tests of high sensitivity and specificity with immediate elimination of reactors produces a dramatic reduction in the disease prevalence. These results might explain the fact that the disease keeps on being endemic in Argentina. Since for achieving eradication at country level, other measures additional to vaccination have to be applied, the mandatory elimination of infected cattle could be taken into account. Summarizing all these issues, it can be concluded that, although there are good regulations to control and eradicate bovine brucellosis in Argentina. The prevalence is not so high and stable throughout the years and, some improvements have to be made in order to achieve eradication. This thesis attempted to assess the Argentine current situation and to provide tools for policy makers and farmers to obtain that goal.   [less ▲]

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See detailLa construction d'un futur sur quatre roues. Une ethnographie du handicap locomoteur dans Mitchell's Plain (Afrique du Sud)
Schnitzler, Marie ULiege

Doctoral thesis (2017)

This thesis explores subjectivities shaped by locomotive disability in the post-apartheid city through an ethnography of ordinary life. Locomotive disability encompasses every limitation of mobility due ... [more ▼]

This thesis explores subjectivities shaped by locomotive disability in the post-apartheid city through an ethnography of ordinary life. Locomotive disability encompasses every limitation of mobility due to an infirmity of the lower limbs. In my discussion, it is conceived as a ‘test’ (épreuve), namely an event that interrupts everyday routines and creates tensions between the responsibilities of different actors’ – people with disabilities, families, the state, etc. These tensions are articulated on various levels. In my discussion, I focus on three of them: the political field that determines a certain type of citizenship, the social networks that constitute the person, and finally the understanding people with disabilities have of their personal history. These levels combine to shape people’s subjectivity, and are analysed in a Foucauldian perspective not just as individuals’ relations with themselves, but also with others and the wider world. [less ▲]

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See detailTowards a system of concepts for Family Medicine. Multilingual indexing in General Practice/ Family Medicine in the era of Semantic Web
Jamoulle, Marc ULiege

Doctoral thesis (2017)

UNIVERSITY OF LIÈGE, BELGIUM Executive Summary Faculty of Medicine Département Universitaire de Médecine Générale. Unité de recherche Soins Primaires et Santé Doctor in biomedical sciences Towards a ... [more ▼]

UNIVERSITY OF LIÈGE, BELGIUM Executive Summary Faculty of Medicine Département Universitaire de Médecine Générale. Unité de recherche Soins Primaires et Santé Doctor in biomedical sciences Towards a system of concepts for Family Medicine. Multilingual indexing in General Practice/ Family Medicine in the era of SemanticWeb by Dr. Marc JAMOULLE Introduction This thesis is about giving visibility to the often overlooked work of family physicians and consequently, is about grey literature in General Practice and Family Medicine (GP/FM). It often seems that conference organizers do not think of GP/FM as a knowledge-producing discipline that deserves active dissemination. A conference is organized, but not much is done with the knowledge shared at these meetings. In turn, the knowledge cannot be reused or reapplied. This these is also about indexing. To find knowledge back, indexing is mandatory. We must prepare tools that will automatically index the thousands of abstracts that family doctors produce each year in various languages. And finally this work is about semantics1. It is an introduction to health terminologies, ontologies, semantic data, and linked open data. All are expressions of the next step: Semantic Web for health care data. Concepts, units of thought expressed by terms, will be our target and must have the ability to be expressed in multiple languages. In turn, three areas of knowledge are at stake in this study: (i) Family Medicine as a pillar of primary health care, (ii) computational linguistics, and (iii) health information systems. Aim • To identify knowledge produced by General practitioners (GPs) by improving annotation of grey literature in Primary Health Care • To propose an experimental indexing system, acting as draft for a standardized table of content of GP/GM • To improve the searchability of repositories for grey literature in GP/GM. 1For specific terms, see the Glossary page 257 x Methods The first step aimed to design the taxonomy by identifying relevant concepts in a compiled corpus of GP/FM texts. We have studied the concepts identified in nearly two thousand communications of GPs during conferences. The relevant concepts belong to the fields that are focusing on GP/FM activities (e.g. teaching, ethics, management or environmental hazard issues). The second step was the development of an on-line, multilingual, terminological resource for each category of the resulting taxonomy, named Q-Codes. We have designed this terminology in the form of a lightweight ontology, accessible on-line for readers and ready for use by computers of the semantic web. It is also fit for the Linked Open Data universe. Results We propose 182 Q-Codes in an on-line multilingual database (10 languages) (www.hetop.eu/Q) acting each as a filter for Medline. Q-Codes are also available under the form of Unique Resource Identifiers (URIs) and are exportable in Web Ontology Language (OWL). The International Classification of Primary Care (ICPC) is linked to Q-Codes in order to form the Core Content Classification in General Practice/Family Medicine (3CGP). So far, 3CGP is in use by humans in pedagogy, in bibliographic studies, in indexing congresses, master theses and other forms of grey literature in GP/FM. Use by computers is experimented in automatic classifiers, annotators and natural language processing. Discussion To the best of our knowledge, this is the first attempt to expand the ICPC coding system with an extension for family physician contextual issues, thus covering non-clinical content of practice. It remains to be proven that our proposed terminology will help in dealing with more complex systems, such as MeSH, to support information storage and retrieval activities. However, this exercise is proposed as a first step in the creation of an ontology of GP/FM and as an opening to the complex world of Semantic Web technologies. Conclusion We expect that the creation of this terminological resource for indexing abstracts and for facilitating Medline searches for general practitioners, researchers and students in medicine will reduce loss of knowledge in the domain of GP/FM. In addition, through better indexing of the grey literature (congress abstracts, master’s and doctoral theses), we hope to enhance the accessibility of research results and give visibility to the invisible work of family physicians. [less ▲]

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See detailEffect of grinding chemistry on the sulphidisation and flotation performances of transitional oxide-sulphide copper ore
Jacques, Simon ULiege

Doctoral thesis (2017)

The influence of pulp chemistry on the flotation performance of sulphide ores has been widely studied. It is well recognised that shifting from a reductive to an oxidative grinding environment affects the ... [more ▼]

The influence of pulp chemistry on the flotation performance of sulphide ores has been widely studied. It is well recognised that shifting from a reductive to an oxidative grinding environment affects the pulp chemistry and improves the flotation performances of sulphide ores. Today numerous operations use high chrome media in their communion circuits for this purpose. However, the role of pulp chemistry on the flotation response of mixed ore is poorly understood. Mixed ore consists of a variety of sulphide and oxide minerals, and forms a part of the supergene enrichment zone of sulphide ore bodies. This study highlights the importance of pulp chemistry for mixed ore recovered by sulphidisation and flotation. [less ▲]

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See detailLa Celestina, un mito literario hispánico (1822-2014)
Francois, Jeromine ULiege

Doctoral thesis (2017)

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See detailAléa climatique et débits des cours d’eau dans le bassin transnational de la Meuse : Co-variabilité, changements possibles et impact sur les débordements
Grelier, Benjamin ULiege

Doctoral thesis (2017)

Climate change is a global socio-environmental concern which required adaptation from human societies in order to compensate negative effects and to take benefit from positive effects. Our research is ... [more ▼]

Climate change is a global socio-environmental concern which required adaptation from human societies in order to compensate negative effects and to take benefit from positive effects. Our research is studying water cycle at the catchment scale and contribute to the adaptation of the transnational Meuse basin to the effects of climate change on hydrological extremes (floods and low flows). To this aim, we adopted a hazard-centered approach. A top-down modelling chain has been set up on two contrasted sub-basins of the Meuse river: the Meuse river at Saint-Mihiel (2543 km², France) and the Ourthe river at Tabreux (1607 km², Belgium). The climate forcing of the chain is constructed on a temporal continuum ranging from the Maunder Minimum (≈ 1650 A.D.) to the end of the 21st century. For the future, climate data are provided by an ensemble of GCMs run in the framework of the Coupled Model Intercomparison Project Phase 5 (CMIP5) and forced with RCP radiative scenarios. For the historical period, gridded data available in the study area are used. Blending past and future climate data is obtained through a transfer function, linking the pressure gradient force to climate forcing variables of catchment streamflow (i.e. atmospheric water and energy supplies). Aggregation of climate data provides a first estimation of potential climatic variability for the two studied sub-basins. The hydrological effect of this potential climatic variability is evaluated in two ways: i) through a regression climate-streamflow transfer function which predicts the streamflow at the outlet of a catchment with the information provided by the pressure gradient force. Regression models are fitted in present climate conditions and used further to extrapolate the streamflow at the outlet of a catchment with CMIP5 GCMs data; ii) through the link between the pressure gradient force and climate forcing variables of streamflow. Regression models are efficient enough to provide robust estimation of the potential climate variability at the scale of interest. The delta-change approach is then applied to potential climate variability to get representative climate scenarios at a daily time step relevant for rainfall-runoff modelling. The tested rainfall-runoff model (GR4J) is calibrated through a climatically robust method. This step gives a first estimation of the two sub-basins sensibility to prescribed climate changes. In order to evaluate the effect of climate change on hydraulic behavior of a river, the modelling chain has been completed with the WOLF1D hydraulic model. Is has been parameterized and validated for a section of the Ourthe river. Boundary conditions were forced with representative climate scenarios to evaluate the climate change effect on overflowing. In a first step, the latter is characterized through overflowing sequences determined through simulated water levels. Then, to overcome the limits of the WOLF1D model in flood-prone area, the flow-duration-frequency behavior of the first overflowing streamflow is studied to show the overflowing evolution under climate change. In the end, our work provides an original framework for studying climate change effect on hydrological extremes through a sampling of climate changes with past and future climate series. The use of a hazard-centered modelling chain is a first step toward adaptation strategies suited for contrasted climate conditions. This contributes in turn to make catchment more resilient. [less ▲]

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See detailTransmission des phytovirus associés aux pucerons: une approche multitrophique
Bosquée, Emilie ULiege

Doctoral thesis (2017)

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See detailEmergent vortex phenomena in spatially and temporally modulated superconducting condensates
Jelic, Zeljko ULiege

Doctoral thesis (2017)

Superconductivity is an electronic state of matter arising from the existence of a common wave function with a coherent phase extending on a truly macroscopic scale. One major manifestation of this ... [more ▼]

Superconductivity is an electronic state of matter arising from the existence of a common wave function with a coherent phase extending on a truly macroscopic scale. One major manifestation of this striking quantum phenomenon is the dissipationless transport of electrical current, an asset deserving particular attention in the present times where the efficient energy distribution has become of utmost importance. Unfortunately, the motion of quantum units of magnetic flux (so-called vortices or fluxons), which is an unavoidable side-effect found in superconductors in the presence of transport currents and magnetic fields, severely limits the conditions to preserve dissipationless transport. This poses a challenge for achieving the functionalization of superconducting materials and threatens their spectrum of applications. It is widely known that any inhomogeneities (either material imperfections, or ones made artificially), which locally suppress superconductivity on the scale comparable to the core of the vortex, can pin the vortex and delay the onset of the vortex motion to higher applied currents. In recent years a substantial effort has been made to minimize the effects of current-induced vortex motion by tailoring arrays of artificial pinning centers. Besides improving the critical parameters of the superconducting state, a pinning matrix can be used for the manipulation of vortex matter, thus directly affecting the vortex dynamics, such as rectification of vortex motion under an ac drive (vortex diode) by introducing asymmetric pinning landscapes. In the literature one can find that the realization of the anchoring of the vortices can be based on nanostructured arrays of perforations, chemically grown defects, permanent nanomagnets, or even pinning sites produced by heavy ion bombardment. All of those realizations are based on a permanent imprint on the superconductor, without any possibility for subsequent modifications in the distribution and strength of the pinning. The principal objective of this thesis is to investigate the dynamical behavior of vortex matter under an entirely new kind of pinning landscape consisting of spatial and temporal modulation of the superconducting condensate. A particular case of spatial modulation is considered in a constricted structure where current lensing can cause extremely high vortex velocities. Subsequently, a time-dependent thermal potential introduced to the superconducting condensate will cause stroboscopic resonances during the vortex motion - a phenomenon that cannot be observed in the systems with static pinning imprints. Finally, a study of electronic gating is presented, where the local properties of superconductor, such as mean free path, or electronic band structure in general, can be influenced electronically. This is a completely unexplored interdisciplinary research topic, which will eventually allow one to manipulate individual vortices in superconducting materials by means of spatially confined and temporally controlled thermal and electromagnetic excitations. Furthermore, such techniques can provide one fundamental insight in different states of the vortex matter with respect to variation of the transport current, highly relevant for understanding the resistive state of superconducting materials and their applications. [less ▲]

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See detailStudy of plant-aphid interactions in Gabonese vegetable crops and biological control perspectives
Bayendi Loudit, Sandrine ULiege

Doctoral thesis (2017)

Periurban agriculture increased vegetables production in the cities. A survey was conducted in three market gardening in Libreville and Owendo cities to register crop and pesticides diversity uses by ... [more ▼]

Periurban agriculture increased vegetables production in the cities. A survey was conducted in three market gardening in Libreville and Owendo cities to register crop and pesticides diversity uses by farmers. The most abundant cultivated species throughout the year appeared to be amaranth (Amaranthus ama L. Amaranthaceae). The most important pests were aphids (Hemiptera: Aphididae) and some beetles (Coleoptera). To control the pests, conventional neurotoxic insecticides were used with effect on environment and human health. In order to identify the occurring insects in the selected areas, a monitoring of insects was carried out during two years on amaranth, roselle, tomato (Lycopersicon esculentum M., Solanaceae) and cabbage (Brassica oleracea L., Brassicaceae). Entomological abundance and diversity were assessed through weekly trapping and visual observations from July to August each year. Insects were collected, identified at the taxonomic level of the family, and classified into three categories: pests, beneficials and associated insects to agriculture. Eighty four families belonging to height orders were recorded with 7910 and 3148 sampled individuals in 2012 and 2013 respectively. The predominant insect families were in both years Aphididae, Cecidomyiidae (Diptera) and Chrysomelidae (Coleoptera) for pests, Dolichopodidae (Diptera), Staphylinidae (Coleoptera) and Coccinellidae (Coleoptera) for beneficials, and Muscidae (Diptera), Psychodidae (Diptera) and Formicidae (Hymenoptera) for associated insects. As aphids are the most important pests, further study at species level and in relation to predatory beneficials were assessed on vegetable crops in 2013 in two periurban gardening sites. The Aphis craccivora Koch aphid was the most abundant aphid species observed infesting amaranth in both sites. The other aphid species were Lipaphis erysimi Kaltenbach, Myzus persicae Sulzer, Aphis fabae Scopoli and Aphis gossypii Glover. Moreover, seven species of natural enemies were trapped, mainly predatory hoverflies (Diptera: Syrphidae) and ladybirds (Coleoptera; Coccinellidae). A. craccivora Koch is known to be a vegetable pest. Its recent identification as pest in amaranth motivated us to study their multitrophic interactions. Since relationships between aphids and host plants could be related to symbiont and feeding behaviour. A. craccivora endosymbiont bacteria and saliva protein diversity were analysed to explain plant–aphid interactions. Indeed, Buchnera aphidicola was found. Some proteins were only identified in solid and soluble saliva, while others originated from Serratia sp. endosymbiont. Two of the identified proteins are involved in plant-pathogen interactions: calmodulin and elongation factor Tu. To control A. craccivora which causes several crop damages, volatile organic compounds (VOC) have been studied. Only aphid alarm pheromone (E)-β-farnesene (EβF) was identified and quantified. Its effect on escape behaviour in aphids has been demonstrated on three species. A. craccivora responded more strongly than the two other Aphidinae (M. persicae and A. fabae) species with 78% of the individuals initiated dispersal behavior at 500 ng dose of EβF. In another laboratory study, the repellency effect of (E)-β-farnesene, methyl salicylate and two essential oils of basil species (Ocimum gratissimum L. and Ocimum basilicum L. Lamiaceae) were determined, while no repellent effect was observed. Also, aphid populations were reduced by exposure to EβF and O. gratissimum essential oil. This study is one of the few to explore the description of insects in the market gardens of Libreville. This could contribute to the elaboration of the sustainable development strategies of pest control in the zones. [less ▲]

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See detailNew therapeutic approaches for malignant pleural mesothelioma targeting DNA repair and transforming growth factor TGF-alpha
Staumont, Bernard ULiege

Doctoral thesis (2017)

Malignant pleural mesothelioma (MPM) is an aggressive cancer of the pleura mainly caused by asbestos fibers exposure. MPM is notably characterized by a very poor prognosis and current treatments ... [more ▼]

Malignant pleural mesothelioma (MPM) is an aggressive cancer of the pleura mainly caused by asbestos fibers exposure. MPM is notably characterized by a very poor prognosis and current treatments, including radiation and chemotherapy, are unsatisfactory. As genomic analyzes show that the major mutations occurring in MPM cells pertain to checkpoint control and DNA repair, a first part of this thesis addresses the DNA damage response and the mechanisms of DNA repair in several MPM cell lines. In this study, we show that gamma ionizing radiation (IR) induces cell cycle arrest of MPM cells at the G2-M checkpoint. We also demonstrate that MPM cells are driven prematurely towards mitosis following the abrogation of IR-induced G2 arrest by the checkpoint inhibitor UCN-01, however without a significant induction of cell death. To avoid excessive genomic instability, DNA repair mechanisms are likely to play a key role in such DNA-damaging conditions. We therefore evaluate here the efficiencies of the two main DNA double-strand break repair mechanisms, non-homologous end-joining (NHEJ) and homologous recombination (HR) and highlight differences in such repair activities among MPM cell lines and in comparison to control mesothelial cells. We underline an efficient HR repair in MPM cells, opening the door to additional investigations that might reveal an addiction to activated DNA repair pathways and thereby render MPM cells hypersensitive to targeted combination therapies. In the second part of this thesis, we perform a pre-clinical study investigating the resistance of MPM to a particular epigenetic-based therapy associating the histone deacetylase (HDAC) inhibitor valproic acid (VPA) and doxorubicin. By comparing MPM cell lines with a differential sensitivity to this combination chemotherapy, this study suggests a correlation between transforming growth factor-alpha (TGF-α) expression and resistance to treatment. We further confirm the role of TGF-α in chemoresistance by modulating its expression in highly- and poorly responsive MPM cell lines. In addition, pharmacological inhibition of TGF-α’s receptor (EGFR or epidermal growth factor receptor) by tyrosine kinase inhibitors gefitinib and erlotinib improves the efficacy of VPA+doxorubicin in vitro. Dual HDAC-EGFR inhibitor CUDC-101 furthermore synergizes with doxorubicin to induce apoptosis in vitro and to slow down tumor growth in two different MPM mouse models, emphasizing its therapeutic potential and opening new prospects for combination therapies associating HDAC and EGFR inhibition against MPM. With two different approaches, this thesis provides a better understanding of MPM resistance to chemo- and radiotherapies and offers clues for new therapeutic strategies based on DNA repair pathways and dual HDAC-EGFR/TGF-α inhibition. [less ▲]

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See detailPLUMAGE DIVERSITY IN BASAL PARAVIANS
Lefevre, Ulysse ULiege

Doctoral thesis (2017)

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See detailIsolation and characterization of nanocelluloses from wheat straw and their application in agricultural water-saving materials
Liu, Qi ULiege

Doctoral thesis (2017)

Humans have been cultivating land for approximately 12,000 years. As such, most countries worldwide have considered crop waste as a global issue linked with environmental protection, economic development ... [more ▼]

Humans have been cultivating land for approximately 12,000 years. As such, most countries worldwide have considered crop waste as a global issue linked with environmental protection, economic development, and healthy living. Many varieties of straw are produced all over China in massive quantities (more than 900 million tons per year). Although banned by the government, stubble burning is widely applied by Chinese farmers as an easy and cheap way to remove stalks after harvests. However, this practice significantly contributes to China’s carbon dioxide emissions and health risks associated with the thick mists it produces. As a renewable biomass resource, straw can be used to make new marketable materials, but its full potential has yet to be realized. Thus, future studies should be directed toward the isolation and rational use of agricultural waste. In addition to the pollution caused by agricultural waste, water shortage, particularly in northern and northwestern China, severely hinders agricultural production. This region accounts for half of the total surface of China but has less than 20% of the total national available water resources. Despite the severity of the water shortage in this region, the efficiency of irrigation water use is only 40%. Many strategies have been applied to promote a water-saving agriculture. One such strategy is the use of water-saving materials, such as plastic mulching films and superabsorbent polymers. However, these two materials are non-biodegradable, and their mechanical properties are unsatisfactory. A systematic analysis of the literature revealed that agricultural waste is a cheap and promising source of raw materials that could be used to obtain cellulose and nanocelluloses. Nanocelluloses can be used for the industrial production of super-strong but lightweight nanocomposite materials. The first step involved the isolation of cellulose, cellulose nanocrystallines (CNCs), and cellulose nanofibers (CNFs) from wheat straw. First, four CNCs were isolated from four commercial microcrystalline celluloses (MCCs) through sulfuric acid hydrolysis. The effects of the characteristics of the MCC on the morphology, structure, and properties of the resulting CNCs were assessed. The results revealed that both particle size and dispersity influenced the isolated CNCs. Second, cellulose was isolated from wheat straw through a microwave-assisted chemical treatment process that reduced chemical use. The reaction conditions and promoting effect of microwave on the resulting fibers were investigated. The results indicated that temperature played the most important role in cellulose isolation, and that microwave can reduce either the reaction time or the chemical use during the microwave-assisted alkali hydrolysis process. High-purity (94%) CNFs were isolated from wheat straw through an environmentally friendly, multi-step treatment process that combined steam explosion, microwave-assisted hydrolysis, and microfluidization. Chemical identification and characterization were performed to study the effect of each treatment step and investigate the potential utilization of CNFs in nanocomposites. Chemical analysis showed that the cellulose content increased from 44.81% to 94.23%, whereas the hemicellulose and lignin contents significantly decreased from 33.41% and 8.75% to 5.54% and 1.68%, respectively. Long and loose 10–40 nm wide nanofiber bundles and an entangled network of cellulose fibers with an average individual diameter of 5.42 nm were observed during this eco-friendly process. In the last part of this study, nanocelluloses were introduced into superabsorbent polymers and mulching films used in agriculture to improve their performance. The effects of nanocelluloses on their structure, properties, and mechanical performance were investigated. First, superabsorbent polymers of acrylamide–acrylate copolymers and others with CNFs, CNCs, or MCC were synthesized. The swelling capacities in pure water and in various solutions, the capacities for repeated water absorption, the water-retaining capacities in soil, and the mechanical properties of the hydrogels were compared. The results revealed that the 3D structures of the acrylamide–acrylate–CNF and acrylamide–acrylate–CNC hydrogels were strengthened by the nanocellulose. These two polymers exhibited excellent capacities for repeated water absorption. By contrast, the biodegradable agricultural mulching film did not present satisfying mechanical and barrier properties as an alternative for ordinary polyethylene film. In this thesis, CNC was introduced into the film of poly (butyleneadipate-co-terephthalate) /polylactic acid composites. Poly(butyleneadipate-co-terephthalate)/polylactic acid/CNC films with various contents of CNC were prepared, characterized, and tested as for their properties. Compared with the film without CNC, poly (lactic acid) / poly (butylene-adipate-co-terephtalate)/3% CNC film showed an increased deformation by 188.80%. The barrier performance of the films increased with increasing CNC content. However, the tensile properties decreased when the CNC content exceeded 3%. Both the mechanical and barrier properties were promoted. These results highlighted that (i) wheat straw is a cellulose-rich natural resource of CNF and CNC; (ii) microwave can reduce either the reaction time or the chemical use during the cellulose-isolation process; (iii) high-purity CNF could be obtained through an environmentally friendly method; and (iv) nanocellulose could improve the mechanical properties of both superabsorbent polymers and mulching films, and enhance their performances in agricultural applications. In a broader perspective, microwave and other techniques should be further explored in the context of green isolation processes. Agricultural biomass natural fiber-based composites must be further investigated to maximize their applications. Approaches that could offer significant cost savings for the industrial production of nanocellulose and new nanocellulose-based materials should be developed further. We aim to promote the research interest for the isolation and application of agricultural-waste-based nanocellulose, which deserve further research and documentation. This thesis is only the beginning of a greater endeavor. [less ▲]

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See detailHorizontal integration under yardstick competition
Teusch, Jonas ULiege

Doctoral thesis (2017)

Horizontal integration through mergers and cross-ownership is ubiquitous; industries regulated by yardstick competition are no exception in this regard. However, even though yardstick competition is ... [more ▼]

Horizontal integration through mergers and cross-ownership is ubiquitous; industries regulated by yardstick competition are no exception in this regard. However, even though yardstick competition is applied to sectors of vital economic importance, such as energy and water networks, the welfare effects of horizontal integration in these settings have largely escaped scientific scrutiny. The dissertation therefore studies the welfare implications of horizontal integration under yardstick competition and identifies potential trade-offs. Specifically, whereas mergers and cross-ownership may bring about efficiency gains, there is a possibility that horizontal integration simultaneously decreases the effectiveness of regulation, benefiting certain firms at the expense of consumers and competitors. Key conditions for such strategic effects to occur and to dominate efficiency effects are derived in a principal-agent model. The thesis also demonstrates that the issue is not merely of academic interest, but has affected the practical application of yardstick competition in the electricity distribution industries of both Belgium and Norway. Chapter 1 analyses how horizontal mergers, joint ventures and regulatory decentralisation complicate the application of yardstick competition in Belgian electricity distribution. Chapter 2 develops a theoretical model of mergers under yardstick competition - formalising the welfare trade-offs at the heart of this dissertation. Chapter 3 leverages Data Envelopment Analysis to quantify both efficiency and strategic effects of horizontal restructuring in Norwegian electricity distribution and points to a recent merger that appears to have been driven by strategic motivations. Chapter 4 uses several econometric identification strategies - dynamic regression, matching on observables and instrumental variables - to establish that between 2007 and 2015, cross-ownership increased firm performance in Norwegian electricity distribution, which suggests that the net welfare effects were positive in this application. [less ▲]

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See detailIn silico modeling of bone formation under the influence of calcium phosphate-based biomaterials and osteochondrogenic growth factors
Manhas, Varun ULiege

Doctoral thesis (2017)

Bone regeneration is a complex process that involves regulation of different cell types by multiple biochemical, physical and mechanical factors. Unlike other biological tissues, bone can heal scarlessly ... [more ▼]

Bone regeneration is a complex process that involves regulation of different cell types by multiple biochemical, physical and mechanical factors. Unlike other biological tissues, bone can heal scarlessly and recover its original shape, size and strength. However, about 5% of bone defects result in non-unions. To tackle these non-unions, tissue engineering (TE) aims to develop bone substitutes or intelligent TE constructs to replace damaged, diseased or aging tissue. These bone substitutes/TE constructs are designed to support the chemotaxis, proliferation and differentiation of bone progenitor cells as well as being a biochemical agent delivery system. However, these delivery systems have a few limitations such as structural weakness of the carrier, high doses of biochemical agents being delivered due to burst release, unknown optimal concentrations of implanted cells and their high cost. Another drawback of these systems is the limited understanding on the relationship between biochemical agent dose, implanted cells, carrier volume, carrier material type and resultant bone formation. Given their significant medical potential, there is an increasing demand to design and develop improved bone substitutes/TE constructs. This PhD work fits in the long-term vision that mathematical models can be used as a part of design and manufacturing processes to develop improved treatment strategies and ultimately save experimental time and costs. In the first part of this work, a novel computational model was developed to predict the in vitro release of Ca2+ ions from calcium phosphate (CaP)-based scaffolds. The developed model was based on the Noyes-Whitney equation, the Fick’s second law of diffusion equation and the level-set method (LSM). The model was dependent on biophysicochemical phenomena such as dissolution, diffusion and degradation along with specific scaffold characteristics such as composition, size and shape. The predictions of the model were compared to dedicated experimental results. In the second part of this work, we investigated the use of a previously reported oxygen-dependent fracture healing model to elucidate the in vivo bone formation capacity of bone morphogenetic protein-2 (BMP-2) delivery systems in an ectopic environment. Specific attention was paid to the influence of BMP-2 dose and carrier volume on ectopic bone formation. The performance of this mathematical model was corroborated by comparison with experimental results published in the literature. Finally, the model was applied to investigate the influence of different BMP-2 release profiles on ectopic bone formation. In the third part of this work, we developed a novel computational model to predict the CaP and BMP-dependent ectopic bone formation in nude mice with and without incorporation of donor cells. The model specifically investigated the influence of BMP-2 dose, donor cell concentrations and calcium ion release on ectopic bone formation. The performance of this mathematical model was compared to the results of dedicated in-house experiments. The model was able to capture essential elements of the experimental results yet at the same time, a number of points for further improvement were identified. In the final part of this work, we investigated the application of the aforementioned CaP and BMP-dependent bone formation model to an orthotopic setting in sheep. The performance of the mathematical model was corroborated by comparing the model predictions with experimental results published in the literature. Subsequently, the model was applied to investigate the influence of different CaP-BMP-cell combinations on orthotopic bone formation, simulating in-house ongoing experiments. In conclusion, this PhD work illustrates a computational step taken towards enhancing the understanding on the role of CaP and BMPs in healing large bone defects. [less ▲]

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See detailCarte interactomique entre l'oncoprotéine Tax du virus HTLV-1 et les protéines à domaines PDZ.
Blibek, Karim ULiege

Doctoral thesis (2017)

HTLV-1 (Human T-cell Leukemia Virus) is the etiologic agent of human adult T-cell leukemia (ATL) and tropical spastic paraparesis (TSP). More than 20 million people worldwide are infected with the HTLV-1 ... [more ▼]

HTLV-1 (Human T-cell Leukemia Virus) is the etiologic agent of human adult T-cell leukemia (ATL) and tropical spastic paraparesis (TSP). More than 20 million people worldwide are infected with the HTLV-1 virus, but only about 5 % develop the associated pathologies. At present, efforts are invested in the search for treatments that may improve the survival expectancy of patients infected by the HTLV-1 virus. The diagnosis of HTLV-1 infection is hampered by the viral genome latency (up to 40 years) and treatment options are limited. To propose novel therapeutic opportunities, it thus is necessary to better understand the host molecular mechanisms perturbed by the HTLV-1 infection. The HTLV-1 genome encodes for the Tax-1 protein, which confers the transforming ability of the virus. The Tax-1 protein is known as the transactivator factor of the HTLV-1 virus genome expression (TransActivator of pX region). It is also involved in the destabilization of several molecular mechanisms within the host, leading to cellular transformation. Tax-1 protein displays several functional domains and interacts with a wide range of cellular proteins. In particular, the Tax-1 protein sequence contains, at its carboxy-terminal end, a motif of four amino acids able to interact with PDZ domain (PSD95-DLG1-ZO1) containing proteins. It has been demonstrated that deletion of the PDZ binding motif (PBM) of the Tax-1 protein leads to a decrease of its oncogenic capacity in vitro. Cellular proteins containing PDZ domains are involved in the formation of cellular junctions, synapses and in cellular receptors assembly. Some of PDZ proteins are capable of relaying extracellular signals and participate in the control of proliferation. The human genome codes for at least 150 proteins with PDZ domains. However, the specificity of the oncoprotein Tax-1 to target these proteins remains unknown. In this study, we have mapped The Tax-1 - PDZ interactome using a combination of several methods. We reveal that Tax-1 selectively target a number of PDZ domains-containing proteins potentially involved in HTLV-1 pathogenesis. We validated our approach by focusing on the role of SDCBP and LNX2 proteins in HTLV-1 biology. Our work also demonstrated that the Tax-1-PDZ interactome might represent an attractive therapeutic target for HTLV-1-induced diseases. [less ▲]

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See detailCaractérisation ontogénique, phénotypique et fonctionnelle des macrophages interstitiels pulmonaires après exposition à des composés bactériens
Sabatel, Catherine ULiege

Doctoral thesis (2017)

Respiratory mucosal surfaces are continuously exposed to harmless antigens and immunostimulatory molecules of microbial origin. According to the « self/non self » and « danger » theories, this should ... [more ▼]

Respiratory mucosal surfaces are continuously exposed to harmless antigens and immunostimulatory molecules of microbial origin. According to the « self/non self » and « danger » theories, this should normally result in the developpment of unwanted immune responses towards these inhaled antigens such as Th2-mediated allergic responses. This is however not the case in most people. The hygiene hypothesis postulates that living in an environment rich in microbial components paradoxically protects from airway allergy, implying the existence in the lung of suppressive mechanisms triggered by these immunogenic signals. In this study, we showed that synthetic bacterial DNA rich in unmethylated CpG motifs (CpG) has the unique ability to significantly increase the population of lung interstitial regulatory macrophages (IM) from CCR2-independent monocytes residing in the lung or mobilized from the spleen. Moreover these CpG-induced IM demonstrated a hypersuppressive profile as they produced more IL-10 than their steady state counterparts. Using mice models of airway allergy we showed that the transfert of IM isolated from CpG-treated mice recapitulated the protective effects of CpG when administered before allergen sensitization or challenge. This IM-mediated protection was dependant from IL-10 as CpG-induced Il10-/- IM had no protective effect. The expansion of pulmonary regulatory IM from CCR2-independent pulmonary and splenic monocytes upon CpG exposure could be a possible mechanism by which exposure to an environment rich in microbial products protects against asthma. [less ▲]

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See detailEtude de la transmission du gammaherpèsvirus murin 4: importance de la glycoprotéine gp150 et développement de stratégies antivirales basées sur l'utilisation du cidofovir
Zeippen, Caroline ULiege

Doctoral thesis (2017)

Gammaherpèsviruses are important pathogens in human medicine. Indeed, Epstein Barr virus and Kaposi Sarcoma associated herpesvirus are responsible for numerous lymphoproliferative diseases and cancers ... [more ▼]

Gammaherpèsviruses are important pathogens in human medicine. Indeed, Epstein Barr virus and Kaposi Sarcoma associated herpesvirus are responsible for numerous lymphoproliferative diseases and cancers. Murid Herpesvirus-4 (MuHV-4) is usually used as a model for human gammaherpèsviruses. Until now, the major limitation of this model was the absence of transmission in laboratory animals. Recently, a sexual transmission of MuHV-4 has been described in laboratory mice. This observation allows, on the one hand, to study mechanisms underlying natural transmission, such as cellular trospism, importance of viral proteins, or immunity response during this part of the cycle. On the other hand, this transmission model allows to test efficiency of measures to reduce transmission. Indeed, herpesvirus are archetype of persistant viruses as infection persists lifelong once established. Studying mechanisms underlying transmission and how to use these mechanisms to reduce it efficiently is therefore of primordial importance. In a first study, we focussed on the biological relevance of mechanisms described previously in vitro. Indeed, a MuHV-4 glycoprotein, gp150, has been shown to participate to the release of infectious particles from cells and to evasion of humoral immunity, two functions that could be important for the virus during transmission. Our results showed that gp150 is essential for an efficient sexual transmission of the MuHV-4. Indeed, gp150 promotes the release of infectious particles from infected vaginal epithelial cells. These results has been published in Journal of Virology in July 2017. In a second study, the same model was used to test efficiency of an antiviral molecule to reduce sexual transmission of the MuHV-4. A nucleotide analogue, the cidofovir, was administrated to mice according to different protocols. A daily administration of cidofovir reduced drastically genital shedding, but also prevent completely infection of naive mice after sexual contact. Finally, a single injection of cidofovir, administered 24 hours after sexual contact, reduced significantly transmission. Altogether, in this work, we used a transmission model of a gammaherpèsvirus in two differents studies: the first foccused on glycoprotein implicated during the transmission and established the importance of a single viral glycoprotein for an efficient transmission. The second study highlighted the efficiency of antiviral drugs to prevent infection by gammaherpesviruses. [less ▲]

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See detailTowards a development of iron phosphate-based materials as positive and negative electrodes for Li-ion batteries
Karegeya, Claude ULiege

Doctoral thesis (2017)

The design, synthesis and electrochemical characterization of new electrode materials hold the key for fundamental advances in energy conversion and storage technologies. Polyanionic compounds have been ... [more ▼]

The design, synthesis and electrochemical characterization of new electrode materials hold the key for fundamental advances in energy conversion and storage technologies. Polyanionic compounds have been heavily investigated as possible electrode materials in lithium- and sodium-ion cells. This thesis focused on the design, synthesis, size and morphology tailoring of iron phosphate based electrode materials in order to enhance their electrochemical properties. Four iron phosphate-based electrode materials classified in three groups: Na2Mn1.5Fe1.5(PO4)3, NaxMxFe(3-X)(PO4)3 (X=1.25 when M=Ni and x=1.5 for M= Mn) and Fe1.19(PO4)(OH)0.57(H2O)0.43, were investigated in this work. All these compounds were obtained through wet chemical (hydrothermal or solvothermal) synthesis routes. The preparation protocols and characterization techniques to study the structural, particle size, morphological and electrochemical properties of the above materials have been discussed in the following chapters. Sodium manganese iron phosphate alluaudite structure is one of the studied compounds group. Na2Mn1.5Fe1.5(PO4)3 is obtained via one step hydrothermal synthesis reaction and it was electrochemically studied without any other further heat treatment. NaxMxFe(3-X)(PO4)3 (X=1.25 for M=Ni and x=1.5 for M= Mn) compounds were obtained through solvothermal method in ethylene glycol. Na1.25Ni1.25Fe1.75(PO4)3 is a new material. Both materials have been electrochemically characterized for the first time in this work. Fe1.19(PO4)(OH)0.57(H2O)0.43 was obtained by modifying conventional hydrothermal synthesis of this materials by the addition of conducting carbon (carbon black and carbon nanotubes) in the precursors solution during synthesis that enhance its electrochemical properties as described in this thesis. The Li-ion intercalation reaction mechanisms in Fe1.19(PO4)(OH)0.57(H2O)0.43 cathode material were also investigated by using operando XRD and Mössbauer spectroscopy techniques. The above studies of iron phosphate-based polyanionics as electrode materials in alkali metal-ion batteries show that this group may be the right key in replacing current commercial unsafe electrode materials. The possibility of improving alternative soft chemical synthesis methods to design new materials or improving electrochemical performance of existing electrode materials was also explored here. The roadmap for our current and future work has been proposed, the materials of our future interest have been chosen basing on their promising rich crystal structure and electrochemical properties by comparing them with the studied materials. [less ▲]

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See detailDevelopment of new catalysts for proton exchange membrane fuel cells (PEMFCs)
Zubiaur, Anthony ULiege

Doctoral thesis (2017)

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See detailCharles de Méan, le Papinien liégeois
Lagasse, Benoît ULiege

Doctoral thesis (2017)

La thèse tend à déterminer si Charles de Méan, surnommé le Papinien liégeois, mérite ce surnom signifiant qu'il a été le plus grand jurisconsulte qu'ait connu la principauté de Liège. Pour ce faire, elle ... [more ▼]

La thèse tend à déterminer si Charles de Méan, surnommé le Papinien liégeois, mérite ce surnom signifiant qu'il a été le plus grand jurisconsulte qu'ait connu la principauté de Liège. Pour ce faire, elle tend à étudier une partie de son oeuvre majeure, les Observationes et res judicatae ad jus civile Leodiensium, Romanorum, aliarumque gentium canonicum et feudale. Par ailleurs, la thèse met en exergue la spécificité du droit liégeois et tend à déterminer les influcences subies par ce droit. [less ▲]

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See detailDesign of a hydraulic nozzle with a narrow droplet size distribution
De Cock, Nicolas ULiege

Doctoral thesis (2017)

Nowadays, pesticides use is necessary to satisfy the growing demand for agricultural products. During pesticide spray application, the agricultural mixture containing the active ingredient is fragmented ... [more ▼]

Nowadays, pesticides use is necessary to satisfy the growing demand for agricultural products. During pesticide spray application, the agricultural mixture containing the active ingredient is fragmented to a cloud of droplets of various sizes and speeds. The droplet size distribution within the spray affects the efficiency of the treatment. According to the target, a specific droplet size should be used. However, hydraulic nozzles usually used in field application produce sprays with a wide droplet size distribution containing an important proportion of small or too large droplets. This results in non-optimal application and therefore losses of product into the environment. This statement conducted the research as early as in the 60’s to create the rotary atomizer. This device is able to produce narrow droplet size distribution using Plateau-Rayleigh break up mechanism. The characteristics of the produced spray by the rotary atomiser can be tuned by adjusting the rotational speed and the volumetric flow rate. Although offering agronomic and environmental qualities this has not met success for the application of plant protection products in field crops because of their cost, size and complexity. The aim of the thesis was the design of a hydraulic nozzle with the rotary atomizer qualities and without the constraints of rotating parts. Unlike the rotary atomizer which has two control variables, the developed hydraulic nozzle will have a narrower operating range, thus a specific geometry has to be design for each kind of treatment. The new hydraulic nozzle design is composed by an inlet pipe ending perpendiculary on a plate. There is a thin opening at the junction between the pipe and the plate. The edge of the plate is constituted of channels formed by structures. These channels aim to divide the liquid sheet in multiple jets. The breakup of these jets into droplets generate a narrow droplet size distribution. The thesis can been seen as a roadmap providing design tools at each step starting from the determination of an optimal droplet size according to the kind of treatment and ending with a nozzle geometry. The prediction of the optimal droplet size according to the treatment was done using integrated modelling approach of the spray transport and retention by the plant. As each spray requires a specific nozzle geometry, an analytical model of the flow on the nozzle was developed. This model allows the determination of geometry according to the desired spray. Finally, a prototype of nozzle has been built. The measurement of the spray characteristics of the prototype was realized using a developed high-speed imaging technique providing the droplet size and speed. The prototype showed results in term of narrowing of the droplet size distribution. [less ▲]

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See detailOn the design of waste heat recovery organic Rankine cycle systems for engines of long-haul trucks
Guillaume, Ludovic ULiege

Doctoral thesis (2017)

The reduction of CO2 emissions from anthropogenic activities is a strategic goal of the EU in which heavy duty vehicles can contribute in a relevant way. A promising solution is the recovery of the ... [more ▼]

The reduction of CO2 emissions from anthropogenic activities is a strategic goal of the EU in which heavy duty vehicles can contribute in a relevant way. A promising solution is the recovery of the thermal energy initially wasted by the engine, which represents around 60 % of the combustion energy. Transforming this heat into mechanical or electrical energy will thus increase the engine thermal efficiency. The conversion can be performed by means of a thermodynamic cycle (e.g. organic or non-organic Rankine cycles) using the waste heat as energy source, as it has already been developed in large stationary applications. Depending on the operating conditions, fuel consumption, and hence CO2 emissions, can theoretically be reduced by 10% to 15%. Nonetheless, the adoption of such technology in the automotive domain requires specific R&D activities to select the working fluid, the components and the most appropriate system architecture in order to achieve sustainable costs and the required level of reliability, while the transient nature of the heat sources available on the truck must be taken into account to evaluate the resulting fuel economy. In this regards, this thesis, based on experimental studies and simulation models, contributes to the characterization and the design of Waste Heat Recovery Organic Rankine Cycle Systems for engines of long haul trucks. [less ▲]

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See detailA TMS–EEG contribution to the multimodal assessment of brain connectivity and consciousness
BODART, Olivier ULiege

Doctoral thesis (2017)

Patients with chronic disorders of consciousness make a challenging population. On the clinical side, establishing an accurate diagnosis is arduous, as the signs of consciousness can be subtle, or even ... [more ▼]

Patients with chronic disorders of consciousness make a challenging population. On the clinical side, establishing an accurate diagnosis is arduous, as the signs of consciousness can be subtle, or even undetectable behaviourally. Both the families and the caregivers need truthful information to make tough decisions about the patient’s management. Transcranial magnetic stimulation, coupled with high-density electroencephalography, is a promising technique to improve our diagnostic ability. The perturbational complexity index derived from this technique is able to distinguish between unconscious and conscious conditions. Its specificity remains to be determined. On the scientific side, the long-standing quest to discover the neural correlates of consciousness is still ongoing. Patients with disorders of consciousness have structural brain damage, and several areas may lose their ability to causally interact in complex patterns with long distance structure. The relation between this ability and structural integrity remains undetermined, despite a vast amount of neuroimaging studies on several networks and connectivities in this population. Our objectives are i) to cross-validate the perturbational complexity index with other neuroimaging techniques, and to determine its specificity, and ii) to determine the relation between global structural integrity and the brain global ability to sustain complex long-range interactions. To do so, we first combined transcranial magnetic stimulation with fluoro-deoxyglucose positron emission tomography, a validated technique studying the brain metabolism, in a population of patients behaviourally characterized by repeated assessments with the gold standard scale, the coma recovery scale – revised. To meet our second objective, we computed and compared the perturbational complexity index and the global fractional anisotropy, a magnetic resonance imaging marker of structural integrity, in patients and in healthy subjects. We found an excellent congruence between electrophysiological and metabolic results in our first study, even in behaviourally unconscious patients showing indirect signs of consciousness. In our second study, we demonstrated that structural integrity largely correlated with the perturbational complexity index, and did not depend on the time since onset or the aetiology. This confirms the diagnostic value of transcranial magnetic stimulation and the perturbational complexity index. It is not only sensitive at the single subject level, but also highly specific. It can detect covert signs of consciousness, as confirmed by other neuroimaging techniques. As such, it could be integrated in diagnostic algorithms and improve their accuracy, leading to better management of these patients. Moreover, the brain’s ability to sustain complex long-range interactions is highly dependant on the global structural integrity. By looking further in detail at the local correlation between these two parameters, our understanding of the emergence of consciousness from fixed structure with variable connectivity would improve. This would be one step forward in the quest for the neural correlates of consciousness. [less ▲]

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See detailAn agent-based framework for modeling travel behavior under disrupted networks
Saadi, Ismaïl ULiege

Doctoral thesis (2017)

Worldwide, floods are the most frequent natural disasters and cause over one third of overall economic losses due to natural hazards. In addition, studies show that flood risk will further increase during ... [more ▼]

Worldwide, floods are the most frequent natural disasters and cause over one third of overall economic losses due to natural hazards. In addition, studies show that flood risk will further increase during the 21st century as a result of climate change. In this context, the objective of this thesis is to implement a methodological framework for modeling the impact of disrupted networks caused by river floods on travel demand. The manuscript is divided into four chapters. In the first chapter, this thesis contributes to the state-of-the-art by presenting an integrated multidisciplinary framework capable of making long-term projections (time horizon 2050 and 2100) with the objective of mitigating future flood risk. Various aspects of modeling are discussed with a focus on the interactions between the different model components. The second chapter is dedicated to multi-source data fusion in transportation research. Indeed, conducting large scale data collection is difficult and requires substantial financial resources. In practice, micro-samples with small sampling rates are generally used for synthesizing populations of households and individuals. Unfortunately, they present important limitations from a qualitative point of view, i.e. lack of representativeness. In this regard, a full population synthesis procedure based on Hidden Markov Model (HMM) has been designed to enable multi-source data fusion and incorporate more heterogeneity into eventual poor data-sets. Our research revealed that HMM outperforms IPF for all the sampling rates smaller than 25% regardless the scalability, while the amount of input data used by HMM is lower compared with IPF. The characterization of activity-travel patterns is described in the third chapter. Indeed, to enable a better understanding of travel behavior, a simulation-based approach for population synthesis has been coupled with a profile Hidden Markov Model (pHMM) in laying the foundation for an innovative activity-based model. There have been several key issues that deserved special attention, in particular the influence of socio-demographics on the activity-travel patterns. We also proposed new perspectives of validation techniques. The simulated and observed activity-travel patterns have been systematically compared on the basis of the emission and transition probabilities. The fourth chapter is dedicated to the case study. The synthesized population is used to calibrate a large scale scenario based on the agent-based framework MATSim to investigate the short-term impact of river floods on travel demand. The model has been tested for Liège, Belgium with multiple flood risk scenarios. Results reveal that the impact in terms of travel times is particularly significant when the network is operating at capacities lower than 50%. [less ▲]

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See detailCopper-based p-type semiconducting oxides: from materials to devices
Avelas Resende, João ULiege

Doctoral thesis (2017)

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See detailEffets de la fertilisation NP et de l'irrigation à des périodes critiques sur le rendement et la qualité des fruits du figuier de Barbarie (Opuntia ficus-indica (L.) Mill.)
Arba, Mohamed ULiege

Doctoral thesis (2017)

Selon la classification révisée récemment, les cactus appartiennent à la famille des Opuntiaceae Desv. (Synon. Cactaceae Juss.), dont le genre-type Opuntia Mill. est économiquement le plus important car ... [more ▼]

Selon la classification révisée récemment, les cactus appartiennent à la famille des Opuntiaceae Desv. (Synon. Cactaceae Juss.), dont le genre-type Opuntia Mill. est économiquement le plus important car il comprend un ensemble de variétés qui participent à la plupart des systèmes agricoles des régions arides et semi-arides. Récemment, dans le Maghreb, la culture de plusieurs espèces et variétés s'est développée à de fins de production fruitière commercialisable, c’est-à-dire répondant à des critères de qualité de plus en plus sévères et exigeant des technologies culturales précises. La partie expérimentale de notre étude s'est déroulée pendant deux années dans le Sud du Maroc, région d'Agadir, sur trois variétés représentatives. Les essais ont été réalisés à la ferme expérimentale de l'Institut Agronomique et Vétérinaire Hassan II, Complexe Horticole d'Agadir (30°36' Nord, 9°36' Est; altitude: 32 m). Le site est caractérisé par des températures moyennes mensuelles qui varient de 8°C en janvier à 31°C en juillet, la température journalière maximale pouvant atteindre 45°C en juillet-aout. La pluviométrie annuelle varie de 100 à 200 mm. La durée moyenne d'ensoleillement est de 8 heures par jour. Un premier objectif de notre étude a été de préciser les réponses quantitatives (rendement en fruits) et qualitatives à des apports modérés d'eau d'irrigation. Un deuxième objectif consistait à évaluer les effets d'apports limités de fertilisation minérale azotée et phosphatée, ces deux éléments majeurs étant les plus susceptibles de se trouver déficitaires dans le contexte pédoclimatique propre à la région. Un troisième objectif a été de préciser la phénologie des trois variétés - surtout les phases de développement floral et fruitier - afin de mettre en évidence d'éventuels impacts des interventions culturales sur la phénologie et de mieux situer les moments de ces interventions en les reliant de manière plus objective à la physiologie du développement. Dans l'étude sur l'irrigation, les variétés utilisées ont été les inermes 'Aissa' et 'Moussa' d'Opuntia ficus-indica (L.) Mill. et l'épineuse 'Achefri’ d’O. megacantha Salm Dyck. En première année, caractérisée par un printemps pluvieux, les traitements d'irrigation ont été: (T1) 0 mm, (T2) 30 mm à la floraison et 30 mm au grossissement des fruits et (T3) 30 mm seulement au grossissement des fruits; les irrigations ont été appliquées entre la mi-avril et la mi-juin. Les irrigations T2 et T3 ont eu un effet négatif sur le rendement en fruits des variétés inermes 'Aissa' et 'Moussa' (-2,8 kg/plant) et T2 a eu un effet positif hautement significatif (p <0,01) sur la variété épineuse 'Achefri’ (+ 2,7 kg/plant ou +18 %). La qualité des fruits n'a pas été affectée par l'irrigation. En deuxième année, caractérisée par un printemps sec, les traitements d’irrigation ont été: (T1) 0 mm, (T2) 60 mm à la floraison et 60 mm au grossissement des fruits et (T3) 60 mm seulement au grossissement des fruits; les irrigations ont été apportées entre février et mai. Toutes les variétés ont répondu positivement à l'irrigation, les augmentations de rendement très significatives (p <0,01) ont varié entre 30% pour 'Moussa' avec T2 et 63 % pour 'Achefri' avec T3 par rapport au témoin non irrigué. Toutes les irrigations ont augmenté le nombre et la taille des fruits et ont provoqué une légère diminution de la teneur en sucres totaux et de l'acidité titrable. Les irrigations n'ont eu aucun effet significatif sur les autres paramètres physiques, chimiques et organoleptiques participant à la définition de la qualité. L'essai sur la fertilisation minérale azotée-phosphorique sur le cultivar ‘Moussa’, mettait en comparaison cinq traitements: 0N-0P; 0N-80P; 40N-40P; 60N-0P et 60N-80P (en kg N ha-1- kg P2O5 ha-1). En première année, l'application de N et/ou de P n'a eu aucun effet sur le rendement en fruits. En deuxième année, les apports de 60 unités de N ou de 80 unités de P2O5 ont augmenté (p <0,01) le rendement de resp. 3,0 et 6,1 kg par plante (+ 18% et + 36%), par rapport au témoin. L'apport simultané des deux éléments N et P (60N-80P2O5) a conduit à une augmentation très significative (p <0,01) de 14,9 kg/plante (+ 90%) mettant en évidence une interaction positive très significative (p <0,01) entre ces deux éléments. Les apports de N et de P ont eu des effets positifs sur le nombre de fruits et leurs poids moyens mais ils n'ont pas modifié le contenu de la pulpe, la teneur en jus, l'épaisseur de l’écorce, la matière sèche du jus, le pH, l’acidité titrable, les sucres totaux, ni le °Brix. L'étude portant sur la phénologie et le développement a été effectuée simultanément dans un essai spécifique reprenant les trois variétés et dans chacun des essais d'irrigation et de fertilisation. Elle a d'une part permis de préciser la variabilité du déroulement des phénologies comme résultant des conditions de milieu (climat), de la génétique, des techniques culturales (fumure et irrigation), et de certaines de leurs interactions. Notre attention s'est portée prioritairement sur les effets des techniques culturales maîtrisables. En première année, les essais ont montré que l'émission de bourgeons est plus élevée (p<0,05) chez la variété épineuse que chez les inermes (plus de 6 bourgeons émis/cladode contre moins de 4,5 chez les variétés inermes). En 2ème année, l'irrigation a augmenté (p <0,05) l'émission de bourgeons chez les trois variétés (plus de 7 bourgeons émis/cladode pour chacun des traitements T2 et T3 vs pas plus que 5 pour T1). L'irrigation a aussi allongé la durée de la phase de floraison de ces variétés. La fertilisation a montré des effets allant dans le même sens. Cependant, ni l'irrigation, ni la fertilisation minérale n'ont modifié significativement la durée de la réalisation du stade maturité du fruit, ne permettant pas ainsi d'allonger la saison de récolte. [less ▲]

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See detailEtude de la relation eaux de surface-eaux souterraines dans un contexte de changements climatiques dans la zone Sud du bassin du Saloum (Sénégal)
Dieng, Ndeye Maguette ULiege

Doctoral thesis (2017)

Situé dans la partie Centre-Ouest du Sénégal, le système hydrologique du Saloum, présente les caractéristiques d’un estuaire inverse du fait du déficit d’écoulement induit par la variabilité climatique ... [more ▼]

Situé dans la partie Centre-Ouest du Sénégal, le système hydrologique du Saloum, présente les caractéristiques d’un estuaire inverse du fait du déficit d’écoulement induit par la variabilité climatique dans la région. La salinité des eaux du fleuve Saloum, particulièrement élevée et supérieure à celle de l'eau de mer, a pour effet une détérioration de la nappe du Continental Terminal (CT) qui est une ressource très importante pour l’approvisionnement en eau potable (AEP) des populations locales mais également pour de grands projets de transfert d’eau vers les zones déficitaires comme les îles du Saloum. Cette présente a pour objectif d’à améliorer nos connaissances sur le fonctionnement hydrodynamique et hydrochimique de l’hydrosystème fleuve Saloum/nappe du CT et à évaluer sa dynamique dans le contexte de changement climatique. Plus spécifiquement, ces travaux visent à : (1) réactualiser les caractéristiques géométriques et hydrogéologiques de l’aquifère du CT en relation avec les eaux du fleuve Saloum, (2) caractériser la salinisation de la nappe du CT, (3) élaborer un modèle hydrogéologique permettant une évaluation des potentiels et des relations eau de surface/nappe à partir de simulations de prélèvements supplémentaires et de scénarios de changements climatiques. L’approche méthodologique utilisée pour atteindre ces objectifs intègre à la fois les aspects sur la télédétection et les SIG, la géochimie des éléments majeurs et isotopiques, l’analyse statistique multivariée et la modélisation. Les méthodes du bilan des chlorures et de Penman utilisées pour l’estimation de la recharge donnent des valeurs comprises, respectivement, entre 17 et 100 mm/an et 19 et 130 mm/an. Ces valeurs ont été spatialement distribuées sur les zones potentielles de recharge fournies par la cartographie. L’analyse statistique par les « Selfs organizinf Map » (SOM) des données géochimiques a permis de distinguer trois types d'eaux souterraines : le groupe 1 (Na-Cl ou Ca-Cl) localisé le long du littoral et du fleuve Saloum est affecté par l’intrusion d’eau salée et/ou une pollution anthropique ; le groupe 2 (Ca-HCO3), principalement situé dans les parties centrale et orientale est caractérisé par une minéralisation résultant de la dissolution de la calcite et enfin le groupe 3 qui indique des processus d’adoucissement susceptibles de représenter l'effet de l’infiltration des pluies récentes. Ces résultats corroborés par l’isotopie montrent une grande variabilité spatiale de la minéralisation des eaux et une certaine cohérence avec le schéma de fonctionnement hydrodynamique établi pour la nappe. L’ensemble des informations apportées par ces différentes approches a été intégré pour développer un modèle conceptuel du fonctionnement hydrogéologique du système qui a été traduit en modèle numérique. Ce dernier est calibré en régime permanent (1970-1973) qui constitue les conditions initiales de la période transitoire (1974-2012). Les résultats montrent que les eaux de pluie, les eaux salées fluviatiles et marines constituent les principales entrées de la nappe. Quant aux flux sortants, ils sont constitués par les pompages (puits et forages) et la décharge de la nappe vers les cours d’eau, la mer et le fleuve Saloum. La légère baisse du niveau piézométrique entre 1974 et 1984 serait le fait du déficit pluviométrique observé depuis les années 70 et de l’augmentation des pompages qui passent de 370 m3/jour en 1974 à 2750 m3/jour en 1985. Durant cette période, les apports proviennent en grande partie de l’intrusion d’eau salée (87 %). A partir de 1986 avec des conditions climatiques plus favorables, on observe une baisse de l’intrusion des eaux salées (11 % des apports) et une remontée du niveau piézométrique, malgré l’augmentation des pompages qui atteignent plus de 8500 m3/jour en 2012. Les simulations prédictives de 2013 à 2050 ont montré que l’effet combiné de l’augmentation des pompages (de l’ordre de 45 %) et de la baisse de la recharge (36 % en moyenne) entraîne des baisses piézométriques variables en fonction des zones considérées. Ce modèle, pourrait être outil d’aide à la décision pragmatique pour une meilleure gestion et orientation pour l’exploitation future de la nappe du CT. [less ▲]

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See detailCaractérisations phénotypiques des populations de pintades (Numida meleagris) locales élevées au Bénin
Houndonougbo, Pascal ULiege

Doctoral thesis (2017)

La pintade (Numida meleagris) est une volaille d’origine africaine. Son élevage est répandu en Afrique subsaharienne dans un système traditionnel où plusieurs variétés sont élevées en liberté. Ces ... [more ▼]

La pintade (Numida meleagris) est une volaille d’origine africaine. Son élevage est répandu en Afrique subsaharienne dans un système traditionnel où plusieurs variétés sont élevées en liberté. Ces variétés qui diffèrent par le coloris de leur plumage sont très peu caractérisées. Au nord Bénin, l’élevage avicole moderne est peu rencontré et la pintade constitue la pondeuse d’œufs de table dans cette région. Mais, la mortalité élevée, la faible productivité de la pintade locale limitent fortement le développement de son élevage. Il est alors nécessaire de caractériser les variétés de pintades élevées pour mieux les valoriser dans un système amélioré. L’objectif de cette thèse est de caractériser phénotypiquement la population de pintade locale élevée au Bénin afin de mieux valoriser l’espèce dans des programmes d’amélioration et de développement du secteur avicole national. Une revue bibliographique (Article de synthèse) a permis de réaliser l’état des lieux de l’élevage de pintade au Bénin et de mieux orienter nos travaux pour une bonne caractérisation des variétés élevées. L’existence de plusieurs variétés dans les élevages a été soulignée dans la revue bibliographique et nous a amené à des enquêtes et un suivi des élevages de pintades en milieu villageois. Ces enquêtes et suivi nous ont permis de caractériser les pintades locales dans leur milieu d’élevage selon les dire des éleveurs. Ils nous ont aussi permis de dégager selon les éleveurs, les objectifs de production, l’importance socio-économique et culturelle des variétés élevées. L’influence de l’alimentation sur les performances technico-économiques des pintades locales a été soulignée dans l’Article de synthèse et l’Article I. Cette influence a été abordée en évaluant l’influence de l’alimentation sur le potentiel de croissance de la pintade locale en station (Article II). Enfin, des travaux ont été réalisés en station pour mieux caractériser les variétés de pintades rencontrées dans les élevages sur le plan morphologique, performances de croissance et de reproduction (Articles III, IV et V). Ces différents travaux nous ont permis de recenser les différentes variétés de pintades locales élevées au Bénin, les objectifs d’élevage des éleveurs ainsi que quelques difficultés liées au développement de cet élevage. Ces travaux nous ont surtout permis de mieux caractériser les variétés rencontrées. Cette caractérisation pourrait être valorisée pour améliorer la productivité des variétés par sélection. [less ▲]

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See detailAnalyse comparée des chaines de valeur du riz dans la plaine de la Ruzizi de la Communauté Economique des pays des Grands Lacs (CEPGL)
Furaha Mirindi, Germaine ULiege

Doctoral thesis (2017)

This thesis aims at carrying out a comparative study of three rice value chains in the Ruzizi plain shared between three countries of the Economic Community of the Great Lakes Countries (CEPGL) namely ... [more ▼]

This thesis aims at carrying out a comparative study of three rice value chains in the Ruzizi plain shared between three countries of the Economic Community of the Great Lakes Countries (CEPGL) namely Burundi, the Democratic Republic of Congo and Rwanda. These include the Burundi rice value chain (Imbo Plain), the Congolese rice value chain (Ruzizi Plain) and the Rwandan rice value chain (Bugarama Plain). The diagnostic analysis was about analyzing the rice-farming environment (ie policies and support services accessed by actors along the value chain), analyzing economic performance of these three value chains and to identify the factors that may foster the development of a value chain with a regional potential. For this purpose, the study adopted the field approach, which allowed carrying out investigations during three years (2013 to 2015). The data collection process involved a sample of 228 actors distributed equitably among the three countries. It combined several techniques, namely, direct stakeholder surveys (producers, processors, collectors, wholesalers and retailers), interviews with various support structures and state services, focus group discussions with producer groups and representatives of their organizations. The analysis of these three value chains driving conditions linked the policies implemented in each country and the access by the actors to certain production factors and services such as land, water, credit and the use of inputs. It also highlighted the issue of wage labor and its different roles in the sector. The analysis shows that land policy in Bugarama plain in Rwanda has reduced the cost of land to more than half compared to land costs in Burundi and the DRC. Moreover, this policy is accused by the producers of Bugarama of limiting their entrepreneurial innovations since they can not enlarge their farms (the cultivated area is 0.23 ha). Despite the high cost of water access and management, all rice plots access irrigation water in Rwanda, while the lack of organization and good water management is one of the factors behind low yields in Burundi and the DRC, where 25% and 40% of the rice plots have difficulties in accessing water. Regarding access to agricultural credit, the results reveal that the value chain of rice in the three countries experiences the lack of funding in spite of improvements observed in Rwanda. The rate of access to credit is 17.5% (in Burundi), 16% (in DRC) and 52.8% (in Rwanda), and among them rice farmers with access to formal credits account for only 8% (in Burundi), 10% (in the DRC) and 37.5% (in Rwanda). Analysis of the wage labour force shows that labor is not as widely available as was thought in the study area. Indeed, the DRC is the zone of deficit in wage labor due to the rural exodus and the diversity of economic activities. In the DRC, 60% of the rice workforce used is foreign, including 46% from Burundi and 14% from Rwanda. This mobility of the workforce leads to technology transfers, the supply of inputs at lower cost, but also to consolidate the social cohesion in a post-conflict context. The economic analysis of these three value chains reveals that production costs in the study area remain very high, varying between 292 and 388USD per ton. The highest costs are observed in the DRC where paradoxically there is a better financial performance in terms of profit and added value. The statistical tests carried out on certain parameters identified by the financial analysis undermines the policies regarding the inputs subsidies, agricultural financing and fixing sales prices. Indeed, there are no significant differences between the means of rice farmers who benefit from these policies and those who do not. Paradoxically, statistical analyzes reveal that rice farmers not affected by the pricing policy (they are not price takers) have a good financial performance in terms of income. The three studied areas are complementary in terms of the development potentials of a regional value chain. Indeed, Rwanda has modern underutilization peeling plants that are capable of responding almost entirely to the needs of the whole plain. In addition, Burundi and the DRC should develop land and water potentials to increase production. Several other regional structures in favor of the regional value chain have to be relaunched or strengthened in logic of rice development in the Ruzizi plain. These include the benefits of economic integration of the CEPGL countries. [less ▲]

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See detailWalking droplets above cavities
Filoux, Boris ULiege

Doctoral thesis (2017)

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See detailLe rôle de la pleine conscience dans l’accompagnement de patients obèses : Quand, pourquoi et comment intervenir ?
Ruffault, Alexis ULiege

Doctoral thesis (2017)

Exposure to adverse life events has been associated with adult obesity, and could translate into the appearance of eating disorders. Moreover, exposure to adverse life events has been associated with ... [more ▼]

Exposure to adverse life events has been associated with adult obesity, and could translate into the appearance of eating disorders. Moreover, exposure to adverse life events has been associated with emotional dysregulation, which would be in turn linked to higher prevalence of eating disorders. Furthermore, mindfulness skills (i.e., non-judgmental awareness of thoughts, emotions, and bodily sensations in the present-moment) have been the object of increased attention in the scientific literature as a means to increase emotion regulation and treat eating disorders in obese patients. The first part of this thesis studies the associations of exposure to adverse life events with eating patterns in obese patients. Two studies have been conducted in this part : the first aiming at assessing the association of exposure to adverse life events with postoperative weight-loss, as well as pre- and postoperative eating patterns ; and the second aiming at exploring the role of emotion regulation strategies and mindfulness skills in the association of exposure to adverse life events and eating patterns. The second part studies the effects of mindfulness training on eating patterns and physical activity in obese patients. Three studies have been conducted in this part : a clinical case study, a systematic review and meta-analysis, and a randomized controlled trial (MindOb study). The results of the first part showed that bariatric surgery patients exposed to adverse life events are at risk of losing less weight after surgery, as well as having more dysfunctional eating patterns pre- and postoperative. Moreover, with non-operated obese patients, the results showed that the psychological impact of adverse life events and nonadaptive emotion regulation have been associated with psychological distress, impulsive eating, and binge eating. The results of the second part showed that mindfulness training decreased impulsive and binge eating in non-operated patients. Moreover, results showed that mindfulness training could also increase physical activity in these patients. This thesis highlights the need for providing obese patients with psychotherapeutic techniques increasing emotion regulation. The results suggest that pre-surgery interventions could avoid maintenance or the appearance of dysfunctional eating patterns. Moreover, psychotherapeutic interventions would be more effective in the case of patients either exposed to adverse life events or being diagnosed with binge eating disorder. However, while mindfulness training seemed effective, the optimal intervention design has yet to be identified. In fact, the questions of whether such training should be self-help or guided, daily and long-term or short-term, complementary tomedical care and adapted to eating disorders or broader, must still be tested. [less ▲]

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See detailAdvanced porosity-based models to assess the influence of urban layouts on inundation flows and impact of urban evolution on flood damage
Bruwier, Martin ULiege

Doctoral thesis (2017)

Worldwide, flood risk is expected to increase over the 21st century due to the combined effect of climate and land use changes. However, while the impact of climate change on future flood risk was ... [more ▼]

Worldwide, flood risk is expected to increase over the 21st century due to the combined effect of climate and land use changes. However, while the impact of climate change on future flood risk was extensively studied, the effects of urbanization remain unclear. The goal of this PhD thesis is to contribute to a better understanding of the influence of future urban development on changes in inundation flows as well as on the related damage. First, an original porosity-based model was developed, which enables efficient computation of urban flooding. It uses anisotropic porosity parameters to reproduce the influence of subgrid-scale obstacles on the flow. An original merging technique was implemented to optimize the computational efficiency in the presence of low values of the storage porosity parameter. Compared to a standard inundation model, the developed model enables speedup factors of the order of 100, while keeping the error on the flow variables at a few percent. Second, we systematically investigated how the layout of buildings located in floodplains influences the inundation characteristics for a long-duration flood scenario. The anisotropic porosity-based model was used to compute the flow variables for 2,000 alternative urban patterns. Correlations between the computed water depths and the urban characteristics reveal which features of the layout of buildings influences most the severity of urban flooding. In particular, the results suggest how the hydraulic effect of new urban development can be effectively mitigated by a suitable location of the buildings preserving a higher flow conveyance at the district-scale. This result provides guidance for more flood-proof urban developments. Finally, we evaluated the evolution of future flood damage as a result of urbanization along all the main rivers in the Walloon region, Belgium. The study was conducted at the regional level using detailed hydraulic results (resolution of 2 to 5 m). Despite high uncertainties in the considered urbanization scenarios, involving both urban expansion and densification, robust conclusions could be drawn, such as the overwhelming influence of banning new developments in flood-prone areas compared to the other tested facets of urban planning policy. [less ▲]

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See detailDevelopment of functionalized materials through sol-gel route for applications in catalysis and surface protection
Léonard, Géraldine ULiege

Doctoral thesis (2017)

In this work, materials have been produced by sol-gel route. This synthesis way has been used for immobilization on a support of a function focused on green chemistry. The different functions are related ... [more ▼]

In this work, materials have been produced by sol-gel route. This synthesis way has been used for immobilization on a support of a function focused on green chemistry. The different functions are related with different applications that allow to illustrate the versatility and the flexibility of this sol-gel process. The two applications are: - Photocatalysis: Synthesis of material with photocatalytic property or with an additional property - Cyclocarbonation: Synthesis of an immobilized catalyst for polyurethane production through a green process The first application concerns the use of a photocatalyst that allows to degrade volatile organic compounds (VOC). The main photocatalyst is TiO2. It has been studied as a powder or as a film deposited on a support. A comparison of these two shapes has shown that an identical photocatalyst can have different performances depending on the final shape. A catalyst must be considered in its totality and with its environment rather than as a chemical composition only. To increase the photocatalyst performances, modifications have been added as the Zn doping to increase the photocatalytic activity and the superhydrophilicity. These new photocatalysts have been compared with pure ZnO and bilayer films composed of TiO2 and of ZnO. Different photocatalytic tests have been performed and depending on the test the best photocatalyst was different. Then, to increase the economic interest, some dopant have been used. In addition of the improvement of the photocatalytic activity and superhydrophilicity, theses dopants add a new property such as electrical conductivity and anticorrosion. First, metallic silver has been incorporated to add antistatic property and to increase the photocatalytic activity. The photocatalytic property has been improved, superhydrophilicity has been kept but no antistatic property was observed. Multiwall carbon nanotubes (MWCNTs) have been tested with TiO2 to increase the electrical conductivity. This doping is efficient because MWCNTs increase the conductivity, the photocatalytic activity and maintain the superhydrophilicity. In addition, anticorrosive property has been observed on stainless steel in a preliminary study with the MWCNTs incorporation. The second study is focused on the heterogeneous cyclocarbonation catalyst synthesis to produce, in fine, polyurethane. The catalyst was immobilized on different matrices that are inert from catalytic point of view but that have a potential activator effect. First, with the preselected catalyst, different supports have been investigated. The comparison between the supports has highlighted the activator effect and the texture influence (accessibility of the active sites) on cyclocarbonation yields. Then, with the optimal matrix, different catalysts from a same family have been grafted to choose the best catalyst. Therefore, it has been possible to define the best catalyst and the best support. With this combination, a kinetic study has been performed to determine the best experimental conditions to produce cyclocarbonates. [less ▲]

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See detailCapturing fine-scale population structure towards molecular reclassification of patients
Chaichoompu, Kridsadakorn ULiege

Doctoral thesis (2017)

During the past decades, population structure analysis has been playing an important role for stratifying populations and tracking back population ancestries. Population structure is mainly due to non ... [more ▼]

During the past decades, population structure analysis has been playing an important role for stratifying populations and tracking back population ancestries. Population structure is mainly due to non-random mating between subgroups in a population because of various reasons, being of social, cultural, or geographical nature. Genetic structure in populations may also arise from known or unknown family relationships. Complex disease analyses, in case-control genetic association studies particularly, can be affected by so-called cryptic relatedness, which refers to unobserved ancestral relationships between study individuals. As population structure may confound results from genetic association studies and studies that aim to detect clinically relevant substructure in patients, its detection is highly relevant. Revealing population structure is really essential. Notably, removing unwanted population structure in molecular-based patient subtypes detection is likely to lead to subtle or fine-scale remaining structure. In this thesis, we developed a novel genetic structure detection tool, hereafter referred to as IPCAPS, which can also be used as, or extended to, a tool for fine-scale reclassification of patients. IPCAPS utilizes a fixation index (FST) to measure the distance between clusters for iterative loop termination. An FST > 0.001 is typically seen as evidence for genetic differentiation between European populations. We also introduced a novel heuristic called EigenFit as one of the stopping criteria. Although our tool has been developed to easily accommodate multiple data types, we have illustrated the conception of IPCAPs and its performance on simulated and real-life data using panels of genome-wide SNP data. SNPs, standing for Single Nucleotide Polymorphisms, are the most common type of genetic variation among people. There are roughly 10 million of them. We evaluated the performance of IPCAPS using a variety of simulation studies and simulation scenarios, including varying sample sizes, varying SNP panel sizes, the absence or presence of outliers, large or very small genetic separation between synthetic populations. The performance of IPCAPS was measured by estimating accuracy and computation time. We observed that our method generally outperformed a selection of other iterative pruning based methods such as ipPCA, iNJclust, and SHIPS. Also in the presence of outliers, IPCAPS' computation time is largely affected by sample size, not by the number of SNPs included in the analysis. We furthermore validated our tools and proposed protocols on a variety of real-life datasets. These datasets differed in complexity and ranged from worldwide sample collections, over regional populations, to geographically confined samples. In particular, we analyzed data from the International HapMap Project, the 1000 Genomes Project, Africa and Thailand. We proposed a suitable protocol to correct for population stratification and to perform patient subgrouping in samples from the International IBD Genetics Consortium (IBD referring to inflammatory bowel disease). All developed analysis protocols involved guidelines for the interpretation of identified strata. In conclusion, IPCAPS is a promising structure detection analysis tool. It was able to identify fine structure in African and HapMap populations, previously unreported. IPCAPS analysis also suggested the presence of at least 3 subtypes of Crohn’s disease and at least 3 subtypes of Ulcerative Colitis patients. More work is needed to evaluate the importance of these findings in clinical practice and for precisions medicine. [less ▲]

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See detailA Combining Approach to Cover Song Identification
Osmalsky, Julien ULiege

Doctoral thesis (2017)

This thesis is concerned with the problem of determining whether two songs are different versions of each other. This problem is known as the problem of cover song identification, which is a challenging ... [more ▼]

This thesis is concerned with the problem of determining whether two songs are different versions of each other. This problem is known as the problem of cover song identification, which is a challenging task, as different versions of the same song can differ in terms of pitch, tempo, voicing, instrumentation, structure, etc. Our approach differs from existing methods, by considering as much information as possible to identify cover songs. More precisely, we consider audio features spanning multiple musical facets, such as the tempo, the duration, the harmonic progression, the musical structure, the relative evolution of timbre, among others. In order to do that, we evaluate several state-of-the-art systems on a common database, containing 12,856 songs, that is a subset of the Second Hand Song dataset. In addition to evaluating existing systems, we introduce our own methods, based on global features, and making use of supervised machine learning algorithms to build a similarity model. For evaluating and comparing the performance of 10 cover song identification systems, we propose a new intuitive evaluation space, based on the notions of pruning and loss. Our evaluation space allows to represent the performance of the selected systems in a two dimensional space. We further demonstrate that it is compatible with standard metrics, such as the mean rank, the mean reciprocal rank and the mean average precision. Using our evaluation space, we present a comparative analysis of 10 systems. The results show that few systems are usable in a commercial system, as the most efficient is able to identify a match at the first position for 39% of the analyzed queries, which corresponds to 4,965 songs. In addition, we evaluate the systems when they are pushed to their limits, by analyzing how they perform when the audio signal is strongly degraded. To improve the identification rate, we investigate ways of combining 10 systems. We evaluate rank aggregation methods, that aim at aggregating ordered lists of similarity results, to produce a new, better ordering of the database. We demonstrate that such methods produce improved results, especially for early pruning applications. In addition to evaluating rank aggregation techniques, we propose to study combination through probabilistic rules. As the 10 selected systems do not all produce probabilities of similarity, we investigate calibration techniques to map scores to relevant posterior probability estimates. After the calibration process, we evaluate several probabilistic rules, such as the product, the sum, and the median rule. We further demonstrate that a subset of the 10 initial systems produces better performance than the full set, thus showing that some systems are not relevant to the final combination. Applying a probabilistic product rule to a subset of systems significantly outperforms any individual systems, on the considered database. In terms of direct identification (top-1), we achieve an improvement of 10% (5,460 tracks identified), and in terms of mean rank, mean reciprocal rank and mean average precision, we respectively improve the performance by 40%, 9.5%, and 12.5%, with respect to the previous state-of-the-art performance. We further implement our final combination in a practical application, named DISCover, giving the possibility for a user to select a query and listen to the produced list of results. While a cover is not systematically identified, the produced list of songs is often musically similar to the query. [less ▲]

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See detailCaractérisation de disques de poussière exozodiacale par interférométrie stellaire en infrarouge proche et moyen
Marion, Lindsay ULiege

Doctoral thesis (2017)

Nous savons aujourd’hui que notre système solaire n’est pas un cas isolé dans la galaxie et qu’il pourrait potentiellement en exister des milliers d’autres. La recherche de ces systèmes est devenue un ... [more ▼]

Nous savons aujourd’hui que notre système solaire n’est pas un cas isolé dans la galaxie et qu’il pourrait potentiellement en exister des milliers d’autres. La recherche de ces systèmes est devenue un centre d’intérêt majeur de la recherche en astrophysique au XXIème. La présence de poussière chaude et tiède est étroitement liée à la présence de planètes dans un système stellaire. En effet, elle provient généralement de la formation du système planétaire, du dégazage de comètes, et de collisions d’astéroides, comme c’est le cas dans notre système solaire. Il est donc devenu primordial de détecter et caractériser la poussière tiède/chaude autour d’étoiles en séquence principale. L’intérêt de l’étude des disques de débris tièdes/chauds est double : d’une part, les détecter et les caractériser nous permet d’obtenir plus d’informations sur la formation d’un éventuel système planétaire et sur la dynamique du système (mécanisme de piégeage de la poussière, ré-approvisionnement du disque de poussière chaudes à partir d’un disque de poussière plus froide, plus éloigné, présence de planètes qui nettoient le disque interne, etc) ; d’autre part, les disques de débris tièdes/chauds peuvent complètement masquer une planète lors de tentatives de détection en imagerie directe. Il convient donc de les détecter pour discriminer ces étoiles pour les missions futures de détection d’exoplanètes par imagerie directe. Le présent travail vise à poursuivre l’étude des disques tièdes/chauds commencée au début des années 2000. Dans un premier temps, nous recherchons la présence de compagnon au sein de l’échantillon d’étoiles dédiées au programme de détection d’exozodis afin de fournir un échantillon non biaisé pour la recherche de disques de débris tièdes/chauds. Grâce aux détections de compagnons, nous révisons également la statistique d’étoiles binaires de type spectral A. Ensuite, dans un nouvel échantillon défini spécifiquement à cet effet, nous étudions la corrélation possible entre présence de poussière tiède et chaude. Nous arrivons à la conclusion qu’il existe une corrélation entre présence de poussière tiède et chaude et que la poussière tiède pourrait donc servir de réservoir à la poussière chaude. Toutefois, pour confirmer ce résultat, d’autres études devront être menées. Ensuite, nous résumons les avancées réalisées au LBTI et mettons en exergue les progrès réalisés sur la méthode statistique de traitement de données pour des observations de nulling. Enfin, nous étudions le système de beta Pic au travers d’observations dans l’infrarouge moyen réalisées avec MIDI. Cette étude nous permet de conclure qu’il n’y a pas de poussière tiède dans les zones internes (~ 1.5 UA) du disque de Pic et que la poussière chaude qui cause un excès en infrarouge proche est probablement alimentée par le dégazage de comètes envoyées dans le système stellaire interne par la planète se trouvant aux environs de 9 UA. [less ▲]

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See detailDroplet manipulation on a fiber network
Weyer, Floriane ULiege

Doctoral thesis (2017)

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See detailPhysical properties of L-type asteroids: a link to the primordial Solar System?
Devogele, Maxime ULiege

Doctoral thesis (2017)

A few years ago, asteroid polarimetry allowed to discover a class of asteroids exhibiting peculiar phase polarization curves, collectively called "Barbarians" from the prototype of this class, the ... [more ▼]

A few years ago, asteroid polarimetry allowed to discover a class of asteroids exhibiting peculiar phase polarization curves, collectively called "Barbarians" from the prototype of this class, the asteroid (234) Barbara. All such objects belong to the L visible plus near infrared based taxonomic class. The anomalous polarization has been tentatively interpreted in terms of high-albedo, spinel-rich Calcium-Aluminum inclusions (CAI) that could be abundant on the surfaces of some of these asteroids, according to their spectral reflectance properties and to analogies with CO3/CV3 meteorites. Such CAIs are among the oldest mineral assemblages ever found in the Solar System. Barbarians' surfaces could therefore be rich in this very ancient material and bring information on the early phases of planetary formation. During this thesis, a systematic campaign for photometric, polarimetric and spectroscopic characterization has been conducted. These observation campaigns allowed improving our general knowledge about these peculiar asteroids and highlighting the link between polarization and polarimetric properties. Our observation also allowed discarding the hypotheses involving peculiar shape for these asteroids. However, as it was suggested, a link between the presence of CAI and the polarimetric response was found. Our observations show that the relative abundance of CAI is correlated with the polarimetric inversion angle. This is the first time that a direct link between polarimetric and spectroscopic properties is found. [less ▲]

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See detailComputer vision systems for automatic analysis of face and eye images in specific applications of interpretation of facial expressions
Hoyoux, Thomas ULiege

Doctoral thesis (2017)

This thesis is about the computer vision-based automation of specific tasks of face perception, for specific applications where they are essential. These tasks, and the applications in which they are ... [more ▼]

This thesis is about the computer vision-based automation of specific tasks of face perception, for specific applications where they are essential. These tasks, and the applications in which they are automated, deal with the interpretation of facial expressions. Our first application of interest is the automatic recognition of sign language, as carried out via a chain of automatic systems that extract visual communication cues from the image of a signer, transcribe these visual cues to an intermediary semantic notation, and translate this semantic notation to a comprehensible text in a spoken language. For use within the visual cue extraction part of such a system chain, we propose a computer vision system that automatically extracts facial communication cues from the image of a signer, based on a pre-existing facial landmark point tracking method and its various robust refinements. With this system, our contribution notably lies in the fruitful use of this tracking method and its refinements within a sign language recognition system chain. We consider the facial communication cues extracted by our system as facial expressions with a specific interpretation useful to this application. Our second application of interest is the objective assessment of visual pursuit in patients with a disorder of consciousness. In the clinical practice, this delicate assessment is done by a clinician who manually moves a handheld mirror in front of the patient's face while simultaneously estimating the patient's ability to track this visual stimulus. This clinical setup is appropriate, but the assessment outcome was shown to be sensitive to the clinician's subjectivity. For use with a head-mounted device, we propose a computer vision system that attaches itself to the clinical procedure without disrupting it, and automatically estimates, in an objective way, the patient's ability to perform visual pursuit. Our system, combined with the use of a head-mounted device, therefore takes the form of an assisting technology for the clinician. It is based on the tracking of the patient's pupil and the mirror moved by the clinician, and the comparison of the obtained trajectories. All methods used within our system are simple yet specific instantiations of general methods, for the objective assessment of visual pursuit. We consider the visual pursuit ability extracted by our system as a facial expression with a specific interpretation useful to this application. To some extent, our third application of interest is the general-purpose automatic recognition of facial expression codes in a muscle-based taxonomic coding system. We do not actually provide any new computer vision system for this application. Instead, we consider a supervised classification problem relevant to this application, and we empirically compare the performance of two general classification approaches for solving this problem, namely hierarchical classification and standard classification ("flat" classification, in this comparative context). We also compare these approaches for solving a classification problem relevant to 3D shape recognition, as well as artificial classification problems we generate in a simulation framework of our design. Our contribution lies in the general theoretical conclusions we reach from our empirical study of hierarchical vs. flat classification, which are of interest for properly using hierarchical classification in vision-based recognition problems, for example for an application of facial expression recognition. [less ▲]

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See detailEffect of different crop residue management on soil hydraulic properties - a study in a silt loam soil in Belgium
Parvin, Nargish ULiege

Doctoral thesis (2017)

In recent decades, agriculture is challenged to develop strategies for sustainability which conserve non-renewable natural resources such as soil. Soil improving conservation systems aim at improving soil ... [more ▼]

In recent decades, agriculture is challenged to develop strategies for sustainability which conserve non-renewable natural resources such as soil. Soil improving conservation systems aim at improving soil functions and at the same time ensuring high productivity. Such soil management systems have to be adapted to climate and soil specific conditions, and may include reduced tillage, balanced crop rotation, retention of crop residues, cover crops, and appropriate timing of field operations. Changes in soil functions have huge impacts on environmental flows like hydrology, crop production, solute transfer, and CO2 emission at macroscale. Soil structure is considered as one of the key factors for soil functioning. The effect of different land management on soil structure and consequently on soil hydrodynamics is not fully understood and still under investigation. The main aim of this thesis was to evaluate the effect of crop residue management on soil structure by measuring soil hydraulic properties in pedon and core scale. The agronomic context was different crop residue management in a reduced tillage system. The experimental field is named as Solresidus located in Gembloux, Belgium. Since 2008, the field has been under conservation system. Different residue management includes reduced tillage with incorporation of crop residues (RT-in) and without incorporation (RT-out). A large part of this thesis was methodological development to obtain accurate results from experimentations. Many studies have been made and documented in literature to develop indirect methods to predict soil hydrology from soil water retention curve (SWRC). There is no measuring device available which can determine the SWRC over the entire soil moisture range. Therefore, one of the methodological developments was to obtain complete SWRC by combining three different methods in core scale: X-ray computed microtomography (X-ray CT), HYPROP evaporation and Richards pressure plate method to obtain the entire SWRC. The combination of these methods found well justified to obtain the accurate and complete SWRC. Saturated hydraulic conductivity (Ks), specific connectivity (SC) of soil pores and bulk density of the soil were also measured in core and pore scale. There were soil moisture sensors (capacitance sensors) in the field to observe the soil moisture dynamics in pedon scale. Another important methodological development was to obtain the calibration results with the moisture sensor according to the soil texture and horizons. Calibration results found quite satisfying to get the accurate moisture content of the field; it was also noticed that it could be over estimation of soil moisture without the calibration. Significantly, average higher moisture content was observed by the moisture sensors in RT-in than RT-out during the canopy formation to harvest of winter wheat in 2014. The SWRCs also showed that plant available water content was higher in RT-in than RT-out. SC of soil pores was also significantly higher at the surface soil of RT-in than RT-out. RT-in found to have significant positive effects on soil structure by reducing bulk density, increasing SC, Ks and retention of soil moisture during the observation period of this study. Crop yield was marginally higher and organic matter content was significantly higher in RT-in than RT-out (results from close collaboration). Therefore, reduced tillage with residues incorporation found to have better soil hydraulics together with better crop yield than reduced tillage without incorporation of crop residues. [less ▲]

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See detailValorisation des sous-produits de la graine de Jatropha curcas L. en production de poulets au Sénégal
Nesseim, Thierry ULiege

Doctoral thesis (2017)

This study evaluated the effects of Jatropha curcas kernel meal incorporated in poultry feed in Senegal. All experimentations were conducted in the experimental station of the National Superior School of ... [more ▼]

This study evaluated the effects of Jatropha curcas kernel meal incorporated in poultry feed in Senegal. All experimentations were conducted in the experimental station of the National Superior School of Agriculture (ENSA) of Thies University (Senegal). In the same way, all chemical analyses were performed in the feed science laboratory of the Department of Animal Production of ENSA. The first part of this study was a description of toxic and anti-nutritional compounds present in J. curcas seed meal, which most important are phorbol esters, characteristics of Euphorbiaceae, known for its inflammatory effects, and curcin, a toxalbumin which manifested by an irritant action. Other compounds, also present, interfere more or less with digestive process in animals. Different treatments were applied, with different levels of success, to reduce or eliminate these toxic and anti-nutritional compounds for the valuation of this meal in animal feed. A particular emphasis was placed on the biological treatment, not only for a significant reduction of these compounds but also to improve the nutritional quality of the meal. The second part of this work has focused on the study of the effect of the J. curcas kernel meal obtained by chemical de-oiling, incorporated in corn at 4, 8, and 12% and distributed to broiler chickens at the end their growth phase to assess their feed intake, their daily weight gain and diet digestibility. For all diets, feed intake was inversely influenced by the incorporation on the jatropha kernel meal, leading a weight gain decrease in animals that received the largest amounts of jatropha despite the absence of toxicity signs and mortality. Similarly, the apparent digestibility of each nutrient has been affected by the incorporation of jatropha kernel meal as well as the differential digestibility thereof. The low digestibility, especially protein was explained by the low availability of meal proteins incorporated corn, but also the presence of anti-nutritional and toxic factors still present in the diets used. The third part of this work has presented results of two experimentations conducted successively. The first one studied the effect of jatropha kernel meal obtained by a chemical de-oiling, incorporated in diets at 4 and 8%, on broiler chickens performance during growing/finishing. The second experimentation studied the effect of the same cake that was heat treated before incorporated in diets at 8%, on day-old broiler chicks’ performance. In one as the other experimentation, feed intake and daily weight gain were affected by the incorporation of jatropha kernel meal. It was the same for the total mortality rates recorded despite the absence of visible signs of toxicity. These experimentations confirmed other experimentations have shown that the de-oiling of jatropha kernel meal followed by heat treatment, even if it caused a significant reduction of anti-nutritional compounds, did not remove all the toxic factors that may even interfere with feed intake and weight gain of animals. These observations were not confirmed in the fourth part, which studied the effects of jatropha kernel meal obtained by chemical de-oiling, subject to heat treatment then biological treatment with Aspergillus niger and incorporated in diets at 8%, on day-old broiler chicks performance. Indeed, the feed intake, the weight gain as well as the viability of animals were not affected by the incorporation of jatropha. These successive studies were among the first which interested the same animal species at different levels of development based on a product whose nutritional quality is proven, but has toxic and anti-nutritional factors could not be completely eliminated despite different treatments applied. The application of heat treatment may have helped to reduce some anti-nutritional compounds (curcin and trypsin inhibitor) but without improve feed intake and weight gain. Considering the reaction of animals subjected to diet, biological and heat treatments may have reduced the toxicity of jatropha kernel meal, which has afected the feed intake of animals and thus the weight gain. This study showed that, despite its nutritional level, J. curcas kernel meal presented limitations in its use as a raw material that can integrate a ration for broilers in Senegal but hopes remain with biological treatments. [less ▲]

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See detailWho Cares for Those Who Cared? An Intersectional Ethnography of Global Social Protection Arrangements
Vivas Romero, Maria ULiege

Doctoral thesis (2017)

How and through which repertoires of practices do migrant domestic workers access global social protection? And how do their gender, race, class, and generational positioning along with their ... [more ▼]

How and through which repertoires of practices do migrant domestic workers access global social protection? And how do their gender, race, class, and generational positioning along with their transnational family relations affect this access? This dissertation deals with these questions and focuses on the case of Peruvian and Colombian Migrant Domestic Workers in the city of Brussels. Such migrants share a paradoxical positioning as they contribute productively and reproductively to the development of their receiving and sending societies but experience a lack of formal and informal social protection on both sides. This analysis first maps through a multi-sited ethnography the repertoire of practices they use to strategize their access to Social Protection in the areas of: 1- old-age and survivors benefits, 2- incapacity, 3- health & family, 4- active labor market programs, 5- unemployment, 6-housing, and education, 7- community and family support. Secondly, it theorizes these practices as Global Social Protection Arrangements that are simultaneously made out of transnational interpersonal relationships and formal support systems. Thirdly, building from the work of Anthias (2016) a Translocations lens is used to analyze how these actor’s gender, race, class, religious and generational positioning within the global reproduction of labor as well as within their transnational family networks simultaneously affect the functionality of such arrangements. Concluding, it’s argued that more privileged migrant domestic workers will use arrangements composed mostly of formal resources, while less privileged ones will see formal avenues less open to them and therefore have to rely on an informal arrangement. Far, from the rights based normative approach to social protection, this thesis provides a glance at how transnational access to social protection is strategize across borders. Furthermore, it’s relevant in a context of increasing human mobility where inequalities in access to social protection emerge as a public transnational social question (Faist, 2016) that is suitable both for academics and policy makers. [less ▲]

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See detailAbundance determination in massive stars: challenges for mixing processes
Cazorla, Constantin ULiege

Doctoral thesis (2017)

Massive stars, the most luminous stars, are the true “cosmic engines” of our Universe. They eject large quantity of material throughout their life, which strongly influences their evolutionary path as ... [more ▼]

Massive stars, the most luminous stars, are the true “cosmic engines” of our Universe. They eject large quantity of material throughout their life, which strongly influences their evolutionary path as well as their environment. An important feature of massive stars is their high rotational velocities that are either acquired at birth or due to the influence of a companion. Rotation is believed to transport nitrogen-rich and carbon/oxygen-poor material generated in the stellar core through the CNO cycle, to the surface. A way to test the e ciency of rotational mixing is to study the chemical composition at the surface of stars, in particular the fastest rotators. The incentive for this study was the discovery, in the context of the VLT- FLAMES Survey of Massive Stars, of fast rotators exhibiting an unenriched nitrogen composition at their surface, contrary to predictions from single-star evolutionary models including rotation. However, their multiplicity may a ect this conclusion, since both rotation and abundances can change as a result of binary interactions. In this work, we combined, for the first time, a detailed surface abundance analysis with a radial-velocity study to quantify the importance of binary e ects. This work was conducted for a sample of 40 bright, OB fast rotators in our Galaxy. Statistical tests and period-search techniques revealed that ≥ 40% of our targets whose multiplicity status can be probed, are binary or binary candidates. We derived the projected rotational velocity of our targets and model atmosphere codes were then used to derive stellar parameters and surface abundances of all sample stars. This abundance study revealed a correlation between the helium and nitrogen abundances of our targets, which is predicted by the rotational mixing theory. Finally, we compared our results to predictions of single-star evolutionary models. We found that 10 – 20% of our 40 targets exhibit no enhancement of the [N/O] abundance ratio, in line with results of the VLT-FLAMES Survey of Massive Stars. The properties of only half of our sample are explained by such models, and surprisingly we also uncovered a quite common large abundance of helium at the surface of our targets. Modifying the di usion coe cient in single-star models and models of non-rotating mergers did not reproduce simultaneously both the observed helium abundances and the [N/O] abundance ratios. Binary models considering a mass-transfer episode can, however, reproduce the [N/O] values of the majority of our targets and even the helium abundances of some of the most helium-enriched targets, but they cannot explain stars displaying little helium enrichment but high [N/O] values. In conclusion, we found that not every feature of massive stars can be explained by models, suggesting that they lack a physical ingredient and thus require further improvements. The second part of this thesis aimed at improving our knowledge of the X-ray emission of early B-type stars. We studied 11 such stars at high resolution thanks to two X-ray facilities, XMM-Newton and Chandra, doubling the number of B-stars analysed at high resolution. In many aspects, our study confirmed previous ones: early B-stars display rather narrow and unshifted lines arising from a warm (of typically 0.2 – 0.6 keV) plasma located at a few stellar radii over the stellar surface. We also found that abundances derived in the X-ray domain are in fair agreement with photospheric ones derived in the optical domain. Furthermore, most early B-stars are moderately bright X-ray emitters – though we also unexpectedly found that this X-ray emission varies, on short and/or long timescales, for half of our sample. A few stars display peculiar features: the presence of a very hot (1.6 – 4.4 keV) component and strong variations. These features suggest that the recorded X-ray emission may not be entirely linked to the B-stars, but could be contaminated by emission from a companion or an interaction with it. Indeed, in one case, HD 79351, a flare was detected, of a luminosity compatible with those from PMS stars, and which could be associated to its companion. Finally, the data used also led to the discovery of the second case of X-ray pulsations associated to beta Cephei activity. [less ▲]

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See detailHollow Nanoparticles for Low Cost, High Activity and Durability for the Oxygen Reduction Reaction for Fuel Cell Applications
Asset, Tristan ULiege

Doctoral thesis (2017)

This Ph.D. thesis investigates the mechanisms driving the formation, the enhanced activity for the oxygen reduction reaction (ORR) and the durability of porous hollow PtM/C nanoparticles (NPs) for proton ... [more ▼]

This Ph.D. thesis investigates the mechanisms driving the formation, the enhanced activity for the oxygen reduction reaction (ORR) and the durability of porous hollow PtM/C nanoparticles (NPs) for proton ex-change membrane fuel cell (PEMFC) applications. The formation and growth of the NPs, synthesized by a ‘one-pot’ process, were discussed in the light of microscopic, operando X-ray and electron-based tech-niques, unveiling the different intermediate steps of the synthesis. The synthe-sis process was extended to different non-noble metals (M = Ni, Co, Cu, Zn and Fe) and to different carbon supports. The enhanced activity for the ORR resulted from (i) the contraction of the lattice pa-rameter by the non-noble metal (the final NPs contains ca. 15 – 20 at. % of M), (ii) the open porosity and (iii) the density of structural defects at the surface of the NPs, which was semi-quantitativey estimated by COads stripping measurements and Rietveld analysis of wide-angle X-ray scattering patterns. The non-noble metal was found to be annealed (dissolved) faster than the structural defects during the accelerated stress tests. [less ▲]

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See detailExperimental study of methods to increase the shielded volume in passive superconducting magnetic screens
Wera, Laurent ULiege

Doctoral thesis (2017)

This thesis is dedicated to the experimental study of methods to increase the shielded volume in passive magnetic shields made of high temperature superconductors (HTS). Two main approaches are ... [more ▼]

This thesis is dedicated to the experimental study of methods to increase the shielded volume in passive magnetic shields made of high temperature superconductors (HTS). Two main approaches are investigated. The first approach is to study how the size of the shield can be increased. The second is to study how the shielded volume can be extended in a shield of given size. In the first approach, we study how large-scale or scalable magnetic shields could be obtained. Scalability means the possibility of building magnetic shields of various dimensions by keeping the same fabrication technique. First, we study in detail the shielding properties and the behaviour of shields made as an assembly of superconducting coated conductor loops, obtained from second generation superconducting YBa2Cu3O7 coated conductor tapes that are commercially available. We show that such shields are an excellent alternative to bulk magnetic shields for shielding large volumes and fields of the order of 50 mT at 77 K. Different dimensions can be easily obtained by adapting the number and the length of the coated conductor tapes. This technique is shown to be very promising for building easily large size magnetic shields. However, unlike bulk magnetic shields, the shielding efficiency decreases rapidly when the applied field is no longer parallel to the main axis of the shield. The results in these configurations are analyzed to investigate the role played by the peculiar eye-shape cross-section of the shield on the various shielding current loops. We show that in the transverse field configuration, the structure can be used to locally modify the direction of the applied field. Finally, we take advantage of the scalability of such shields to build and study a triaxial structure that is able to attenuate a magnetic field of arbitrary orientation. Next we study the superconducting properties and the shielding efficiency of YBa2Cu3O7 superconducting tubes made by two distinct fabrication techniques allowing large-scale or scalable magnetic shields to be obtained. The first technique is the electrophoretic deposition (EPD) which consists in the deposition of a superconducting thick-film (about 100 μm thick) on a metallic substrate. Compared to previous studies, our results show an improvement of the shielding properties and open encouraging prospects for a future development of magnetic shields made by EPD. For the second technique, the shield is obtained by the pulsed-laser deposition (PLD) of a superconducting thin layer (about 1 μm thick) on a textured metallic substrate. In the case where a continuous layer (i.e. joint-free) has been deposited successfully, we show that the persistent current flowing in the superconducting layer has a critical current density close to that of the commercial YBa2Cu3O7 coated conductor tapes, and point out the similarities with the coated conductor structures studied previously. We also consider a similar material containing joints and compare their impact on the magnetic shielding in various configurations (DC/AC, axial/transverse). The results highlight the profound impact of nΩ level joint resistances on the superconducting shielding. For the second approach used in this thesis, we study how to increase the shielded volume in HTS bulk magnetic shields of given dimensions. In the case of non-textured polycrystalline superconductors (Bi2Sr2Ca2Cu3O10 commercial tubes), we analyse the improvements resulting from closing one or both ends of a tube by a cap made of the same material. In this configuration the joint between the cap and the tube is non-superconducting. Numerical simulations are used to see how the volume can be further increased by increasing the thickness of the cap or increasing its critical current density. Then, we study the shielding efficiency of a melt-textured bulk YBa2Cu3O7 superconducting tube closed at one extremity with a cap in which the joint between the cap and the tube is superconducting. Our results show that such a tube can shield axial fields in excess of 1 tesla at 20 K and is therefore useful for shielding small volumes against high magnetic fields. The beneficial effect of a cap is also studied in the transverse field configuration. We show experimentally and with help of numerical simulations that, in this case, the superconducting character of the joint between the tube and the cap is mandatory. In addition to the increase of the shielded volume, this thesis also addresses another problem relevant to future shielding applications. We investigate experimentally the effect of a magnetic field trapped initially in a bulk HTS hollow cylinder on its shielding performances. In the studied configurations, the initial applied field and the field to be shielded are mutually orthogonal. Remarkably the shielding properties are not affected provided the flux lines have not reached the inner hollow part of the cylinder. A trapped field inside the shield, however, is found to affect the threshold induction significantly. We then study how to efficiently demagnetize the superconducting tube without heating it above its critical temperature. By applying a single demagnetization cycle of adequate amplitude, we show that the initial shielding properties can be recovered. [less ▲]

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See detailContraintes et stratégies d’amélioration de la filière maïs au Rwanda
Musabanganji, Edouard ULiege

Doctoral thesis (2017)

For more than a decade, Rwanda has adopted a series of policies and strategies aimed at economic development and the improvement of the living conditions of its predominantly agricultural population. In ... [more ▼]

For more than a decade, Rwanda has adopted a series of policies and strategies aimed at economic development and the improvement of the living conditions of its predominantly agricultural population. In agriculture, implementation of these strategies and related programs has been accompanied by a series of advances in the adoption of farming technologies and increasing agricultural production. However, the country's economy is still characterized by subsistence agriculture, and for the maize sector in particular, the country is continuously depending on imports to meet domestic demand, and maize processing plants always operate below their productive capacity. This research aims to examine the level of competitiveness of this sector in the current production and marketing conditions in order to identify existing constraints and formulate the strategies that can improve the level of economic performance of maize production and maize marketing system. The data used to study the economic performance of maize production come from close monitoring of maize production activities on a sample of 50 producers from five maize producers’ cooperatives selected in the districts of Huye, Rusizi, Gasabo, Burera and Bugesera during two growing seasons. They were supplemented by direct observation, interviews with targeted resource persons, and focus group discussions. The analysis was done using group analysis and appropriate statistical methods. The study of the maize marketing system used the 'Structure-Conduct-Performance' model with data collected from a sample of 150 producers and 17 assemblers selected in the districts of Burera, Bugesera and Huye, and 15 transporters, 5 wholesalers and 15 retailers selected at the national market of Kigali. The results revealed that for many producers, the yield is very low compared to theoretical expected yields, production costs are higher and exceed sales prices, gross margin and family labor income are negative, and the gross added value created by maize producers is not high even though it is positive. The analysis showed that the increase in the selling price positively influences the gross margin, added value and family labor income, and that the rational use of improved seeds, chemical fertilizers and soil conditioners improves the yield. This clearly shows that improving the selling price and rational use of inputs can significantly contribute to making maize production a more profitable and income-generating activity. The study also identified challenges that hamper the production process. These include non-availability of, and low access to inputs, inadequate technical support, limited financial resources and low access to formal agricultural credit, high marshlands rental fee, method of fixing the maize floor price and lack of mechanisms ensuring its use by potential buyers, the lack of storage infrastructure, and the unsustainability of inputs subsidies granted by the government. At the marketing level, the results revealed that several actors are involved in the marketing of maize. The study also revealed that maize imported from Uganda is sold on domestic market at lower prices than locally produced maize, which attests the increase in the cost of maize production in Rwanda compared to Uganda and the low level of competitiveness of the local maize compared to Ugandan maize. The improved status of feeder roads and the high level of access to price information by actors were highlighted among the technological innovations that helped improve the marketing system of foodstuffs in general and maize in particular, which was also evidenced by the level of integration observed between districts maize markets and the national market of Kigali. However, the lack of enough capital and low access to formal credit were noted as major constraints by most of the chain actors. In the light of all these results, it is clear that the production and marketing of maize are not done in good conditions at all levels. This in turn undermines the sector's ability to respond adequately to domestic demand, generate income for actors and integrate itself into both domestic and regional markets. Therefore, strategies aiming at scaling-up the maize production and marketing, and improving working conditions of the sector operators were recommended. These strategies include the implementation of actions to improve access to finance by farmers and other actors; making inputs avail and accessible; reorganizing the marketing system especially in terms of fixing and using the floor price; making available storage facilities where necessary; improving the monitoring, training and sensitization of maize producers on farming techniques and the use of improved technologies; and harmonizing the marshland rental fee at national level. [less ▲]

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See detailDéfinition d’un outil d’aide à la décision spatiotemporel structurant et articulant les potentialités de développement agricole : cas du Niger
Andres, Ludovic ULiege

Doctoral thesis (2017)

The concern about food insecurity in rural populations needs to be rethought and adapted to the overall living conditions of households by shifting to a concentrated spatial scale and a long-term analysis ... [more ▼]

The concern about food insecurity in rural populations needs to be rethought and adapted to the overall living conditions of households by shifting to a concentrated spatial scale and a long-term analysis. This change will allow identifying territories on a finer scale than the national level in order to allocate development objectives and to link them to areas with high development potential. The finer level of analysis will also allow regrouping the actions carried out on a smaller scale in order to structure all the activities carried out on the targeted area and population. The general comment that the development and emergency aid has been focused in circumscribed areas and that the level of analysis is based on two scales, one "macro" (national, regional, departmental) and the other "micro" (village, community, household, individual and community) reinforces the need to create an intermediate level of analysis. The latter will serve to improve the structure other actions carried out at different levels and the articulation of the activities to be carried out and the targeted population. From a state of the art analysis of subject such as development, targeting, territory, food security, resilience, etc; different finding have led to the definition of a major question and an objective which form the core structure of the present dissertation. The research question is defined as "how to structure the targeting and identification of areas with high potential to articulate all the emergency and development actions carried out on several scales of analysis?”. At the end of these observations, the objective of this research is "the establishment of a tool to support spatial and temporal decision making in structuring the emergency and development actions and targeting of populations subjected to food insecurity ". Three considerations emerge from this objective and research question: spatiotemporal analysis and targeting, development potentials, rural production systems. The various productions are also studied over a long series in order to consider the yield variations over time. Finally, these two analyzes, spatial (systems) and temporal (yields) are crossed in order to demonstrate the contribution of this decision-supporting tool in the articulation and structuring of the other two levels of targeting populations to food insecurity. The decision-supporting tool has been tested on the case study of the Nigerian population. The main outcomes are: the characterization of the opportunities and constraints of the Nigerian rural production systems; the identification of the products to be developed by production system; the identification of the most promising pathways by means of the distribution of the yields by systems. Finally, an essential point must be made about the increase of conservation methods and transformations for increasing the added value obtained by Nigerian households. At the end of this dissertation, the tool demonstrated its importance in structuring and articulating the targeting of food insecurity in the field of emergency aid and development: The territorial zones in the production systems identify the problems to which one or several solutions must be found. Production systems allow a concentration of actions according to the definition of the general and specific objectives of the agricultural development assistance programs. Potential outputs to be developed in production systems allow diversification of agriculture and structuring of development from a national point of view. The actions defined by the Technical and Financial Partners at the level of a village, a community and / or a commune can be more easily integrated into this scale of analysis and can be structured later in national development policies Agricultural policy. The increase in productivity in Niger depends on the development of products within the most favorable zones and not on the whole territory. However, this tool is complementary to the other targeting tools already in place. It should also be complemented by the same type of analysis at the level of West Africa and an analysis of the flows and prices condition to favor the flow of production. [less ▲]

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See detailLipin-1 regulates cancer cell phenotype and is a potential target to amplify the effect of metabolic inhibitors
Brohée, Laura ULiege

Doctoral thesis (2017)

An increased lipogenesis was reported in various cancers and its inhibition represses proliferation and induces apoptosis of cancer cells while barely affecting most normal cells. The family of lipins ... [more ▼]

An increased lipogenesis was reported in various cancers and its inhibition represses proliferation and induces apoptosis of cancer cells while barely affecting most normal cells. The family of lipins encompasses three members: lipin-1, -2 and -3. All exhibit dual functions as enzymes, catalyzing the de-phosphorylation of phosphatidic acid to diacylglycerol, and as co-transcriptional regulators. Thus, they are able to regulate lipid homeostasis at several nodal points. However, no studies addressed the involvement of these proteins in cancer progression neither in vitro nor in vivo. During this PhD work, we first investigated the importance of lipin-1 on prostate cancer cell phenotype. We showed that lipin-1 expression is increased in various cancer cell types both in vitro and in vivo in human prostate tumor samples. The specific inhibition of lipin-1 in prostate and breast cancer cells demonstrated its critical importance for cell proliferation and migration through deregulation of several intracellular signaling pathways. This study demonstrated for the first time that the targeting of lipin-1 is a potential new anti-cancer strategy that could be used alone or in combination with drugs like rapamycin. During the course of these investigations, we also observed a compensatory regulation between lipin-1 and lipin-2 preventing the complete inhibition of lipins enzymatic activity when using a siRNA approach. Therefore, we focused our interest on inhibiting all lipins through treatment with a pharmacological inhibitor, propranolol. This drug also induced a blockade of the late phases of autophagy, likely because the inhibition of all lipins decreases diacylglycerol synthesis, which is required for the maturation of autolysosomes. Autophagy is a pro-survival mechanism induced by several stresses or by anticancer agents. In the case of the glycolysis inhibitor 2DG, the induction of autophagy limits its anticancer effects in monotherapy. In the light of their individual specific effects on cancer cells, we hypothesized that the combination of propranolol and 2DG might exert a more than additive toxic effect on cancer cells. In this second study, we report that combined treatment is effective on preventing prostate cancer cell proliferation, inducing cell apoptosis, altering the function of several organelles as mitochondria, endoplasmic reticulum and Golgi apparatus in vitro but also in suppressing tumor growth in vivo. Altogether, our data suggest that lipins are key players involved in cancer progression. Targeting lipins, alone or in combination with other treatments, could open new avenues in anticancer therapy. [less ▲]

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See detailPhenotyping hygienic behavior and studying diversity in honey bees (Apis mellifera L.): methodological issues and solutions
Leclercq, Gil ULiege

Doctoral thesis (2017)

Honey bees (Apis mellifera L.) are a crucial resource for world agriculture. The global stock of honey bees has increased over the last five decades. In contrast, honey bees have been declining in several ... [more ▼]

Honey bees (Apis mellifera L.) are a crucial resource for world agriculture. The global stock of honey bees has increased over the last five decades. In contrast, honey bees have been declining in several regions, especially in the northern hemisphere. Among the factors responsible for these regional declines, the parasitic mite Varroa destructor plays a central role and is considered as one of the main threats for apiculture. A sustainable solution to the problems caused by V. destructor is to breed Varroa-resistant honey bees. In this context, in Belgium, a research project was developed with the aim of studying the diversity of honey bees in Wallonia, and selecting, within this “local” diversity, Varroa-resistant honey bees. This project required methods to accurately phenotype Varroa-resistance traits, and methods to study the diversity of honey bee populations. In this thesis, we decided to work on these methods, which are a prerequisite for such research project. Two independent objectives were developed: (1) solving the controversy and methodological issues regarding the quantification of hygienic behavior in honey bee colonies, and (2) designing a new method to study the diversity of honey bee admixed populations covering a large-scale area, using pool-based sequencing data. The hygienic behavior of worker bees contributes to the social immunity of honey bee colonies. The manifestation of this behavior consists in detecting and removing unhealthy or dead brood. In this thesis, we reviewed the drawbacks, the benefits, and the methods to test for hygienic behavior, in honey bee colonies. We concluded that, while hygienic behavior was efficient against some brood diseases, it was difficult to draw any definitive conclusion on the efficiency of this behavior against V. destructor. Hygienic behavior likely contributes to Varroa-resistance, but the controversy is fueled by the use of inappropriate bioassays to quantify the hygienic removal of Varroa-infested brood. In our experiments, we showed that a commonly used bioassay, the freeze-killed brood removal bioassay, was unreliable to approximate the benefits arising from the hygienic removal of Varroa-infested brood. As an introduction to the second part of the thesis, we reviewed how human has contributed to reshape the diversity of honey bee populations worldwide, except in Africa. Human management was shown to increase the proportion of admixed populations, sometimes to the detriment of subspecies populations (such as in Belgium). Then, we presented a new approach to study the admixture of hybrid honey bee populations. It was based on a reduced representation of the genome (through genotyping-by-sequencing). In this approach, we enabled the use of pool-based sequencing data by simulating an individual genotype for each pool, sampled from a hybrid colony. Finally, some conclusions and discussion were brought on a few perspectives and research avenues about (1) the phenotyping of hygienic behavior towards Varroa-infested brood, and (2) the study of admixture in honey bee populations. [less ▲]

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See detailStochastic multiscale modeling of MEMS stiction failure
Hoang Truong, Vinh ULiege

Doctoral thesis (2017)

In the context of microelectromechanical systems, due to their reduced size, the surface phenomena, e.g. adhesion contact, play an important role in the reliability of the devices. Indeed, the adhesive ... [more ▼]

In the context of microelectromechanical systems, due to their reduced size, the surface phenomena, e.g. adhesion contact, play an important role in the reliability of the devices. Indeed, the adhesive forces, e.g. capillary and van der Waal forces, can lead to the stiction failure for which the two contacting surfaces can accidentally be stuck together permanently. This is a common failure of MEMS. Because of the comparability between the roughness of the contacting surfaces and the ranges of adhesive stress, the interaction area can be much smaller than the apparent one. Since the contact zone is reduced and becomes comparable with the characteristic length scale of the surface roughness, the behaviors of micro structures subjected to adhesion suffer from a scatter, i.e. while some devices are unstuck, the others with an identical design are stuck. The objective of this work is to predict in a probabilistic way the adhesion behaviors of MEMS by accounting for the randomness of the contacting surfaces. The straightforward solution toward this end consists in constructing a numerical model, e.g. using finite element method, and in performing a Monte-Carlo simulation (MCS) directly on that model. Because the problem spans multiple scales, including the nanometers range of adhesive stress and the micrometers length scale of MEMS, that method demands a huge computational cost and becomes unpractical. In this work, a stochastic model-based multiscale method is developed to fulfill the predefined objective while remaining efficient in terms of computational cost. In this model, MCS is also per- formed, however, in a scale-by-scale way. With this method, the model is executed with acceptable computational cost. To verify the proposed model, a comparison in terms of the numerical predictions obtained from two approaches, direct MCS and stochastic model-based method, is performed. Furthermore, the model is applied to simulate the stiction tests reported in the literature, and also on the experimental surfaces fabri- cated by our partner at IMT-Bucharest lab 1 (without stiction test). By comparing the numerical predictions with the experimental results, the model is then validated. The model is used to broaden our knowledge in stiction phenomenon by considering the effects of the following aspects on the adhesion energies: the roughness of surfaces, the non-Gaussianity in the probability distribution of surface heights, and the humidity of the environment conditions. Furthermore, the comparison between different sources of uncertainty, e.g. due to the surfaces roughness and in the geometry dimensions of the devices, is performed. [less ▲]

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See detailEnvironmental sustainability of the Walloon cereal sector using Life Cycle Assessment (LCA) fed with local data - Current situation and potential evolution scenarios
Van Stappen, Florence ULiege

Doctoral thesis (2017)

In a world facing a growing population and diminishing resources, agriculture has a major role to play in terms of sustainable provision of food and feed, job creation in rural areas, preservation of ... [more ▼]

In a world facing a growing population and diminishing resources, agriculture has a major role to play in terms of sustainable provision of food and feed, job creation in rural areas, preservation of natural resources and climate change mitigation. As a very intensive agricultural region, Wallonia (southern Belgium) dedicates more than half of its arable land to cereal crops. Thanks to a long history of research and development, rich soils and favorable climate conditions, yields of cereals such as wheat or barley cropped in Wallonia are amongst the highest in the world. As a major sector in the Walloon agricultural landscape, the cereal sector therefore calls for production and processing opportunities that meet the requirements for sustainable agriculture. In this context, the objectives of the present thesis were to evaluate the environmental sustainability of current and potential evolution scenarios for the Walloon cereal sector using the Life Cycle Assessment (LCA) methodology fed with local data. On the basis of current uses of cereals grown in Wallonia, this research aimed first at describing various scenarios for the future of the Walloon cereal sector. Based on contrasting hypotheses, four scenarios for the uses of Walloon cereals by 2030 were defined with the support of stakeholders involved in all parts of the sector. Issues such as competition between food uses (both direct and indirect) and non-food uses or Walloon dependency on cereal imports were addressed in these scenarios, which illustrate contrasting future situations, from food self-sufficiency to drastic globalization, through the development of new outlets combining changes in crop-growing practices and consumption habits and new technologies. Using the widely used, yet continuously improved, methodology of LCA, the second part of this work evaluated the environmental impacts of cereal production in Wallonia. It identified the production steps with the greatest contribution to environmental impacts. The leading contributor was mineral fertilizer production, for which this work used up-to-date data from best available technologies and demonstrated the importance of using such recent data. The second greatest contributor to environmental impacts was emissions from mineral and organic fertilizer use on field, before and during plant growth until harvest. As well as being very important, these emissions are also extremely variable, depending on agricultural practices, soil and weather conditions, and thus particularly difficult to assess. This is particularly true of nitrogen- and carbon-related emissions, whose dynamics are very problematic to evaluate. This work demonstrated the limits of commonly used emission models, which use generic emission factors and therefore weaken LCA results. As a result, the use of more specific models, based on field trials and adapted to local conditions, was placed at the top of the list for future research in this area. From a methodological point of view, this part of the work also confirmed the influence of the functional unit used to express LCA results. It showed the strong link between yield and environmental impacts, and identified cereal crops demonstrating efficient input management, with lower impacts per kilogram of product, per hectare and per euro. Other methodological choices, such as the choice of allocation factor between grain and straw, also showed their relevance. In short, this part of the work demonstrated the pertinence of using local data to feed LCAs of agricultural productions and identified the most sensitive parameters to be adjusted in priority to achieve good quality LCAs. Thirdly, on the basis of an original methodology comparing equivalent balanced animal diets, a case study on cereal processing in a biogas plant assessed the consequences of diverting feedstock from the animal feed industry into the bioenergy sector. Despite the environmental benefits brought by fossil fuel displacement and digestate use as organic fertilizer, the replacement of raw materials previously used as animal feed induces additional impacts potentially more important than the benefits of this technology. The key message from this finding is that it is urgent to stop using potentially edible raw material for bioenergy production. The only countervailing consideration here is that current trends towards decreasing meat consumption would in the longer term make lands and raw material available for purposes other than animal feed. The strength of all the LCA results in this work was tested using a wide range of sensitivity and uncertainty analyses. These good practices, often neglected due to time constraints, proved to be essential to be able to draw robust conclusions. Through the application of LCA to the Walloon cereal sector, this work had some practical implications for enhancing the quality of LCAs of agricultural productions. It showed the sensitivity of the method to the use of local data and demonstrated the strengths and limitations of the method. It has produced specific LCA references for cereal production in Wallonia, which are useful for feeding environmental impact assessments of cereal-based products sourced with Walloon cereal crops. Further improvements could include the use of specific models to assess on-field emissions from fertilizer use and the consideration of additional impact indicators regarding soil organic stock changes, biodiversity impacts and water consumption. Additionally, assessing impacts at the rotation scale would reflect more accurately the way farmers optimize their crops and allow for the evaluation of more diverse cropping systems. [less ▲]

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See detailOf trees and men: new insights into man-environment relationships in the moist forests of central Africa during the late Holocene
Morin, Julie ULiege

Doctoral thesis (2017)

In central Africa, vegetation history has been documented by paleoenvironmental studies (especially palynology), which mainly concerned the way climate has shaped the forest landscapes. Human impacts in ... [more ▼]

In central Africa, vegetation history has been documented by paleoenvironmental studies (especially palynology), which mainly concerned the way climate has shaped the forest landscapes. Human impacts in this region have hardly been studied so far, especially at local scale. The main objective of this PhD is to propose an approach based on archaeology and the use of charred botanical remains found in soils, either wood charcoal or seeds, in order to document the Holocene anthropogenic impacts on the forest structure and composition. When coupled with the diachronic analysis of human activities, these land-use biomarkers can allow a better understanding of the relationship between man and his environment in central Africa during this period. Thereby, the first part of this PhD introduces the conceptual framework and the materials and methods used during the research. Then, the second part constitutes the core of the work, and presents the chronology of human activities in the northern Congo Basin, the use of biomarkers to discrimate between these activities, either domestic or agricultural, and the effect of the recent anthropogenic activities in the dynamic of several light-demanding tree populations. Finally, the third part draws the main recommendations of the work, and formulates potential for additional research. [less ▲]

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See detailPush-Pull strategy to control aphids in Belgium and China
Xu, Qingxuan ULiege

Doctoral thesis (2017)

Wheat (Triticum aestivum L.) is one of the most cultivated crops in temperate climates. As its pests are mainly controlled with insecticides which are harmful to the environment and human health ... [more ▼]

Wheat (Triticum aestivum L.) is one of the most cultivated crops in temperate climates. As its pests are mainly controlled with insecticides which are harmful to the environment and human health, alternative practices such as intercropping have been studied for their potential to promote biological control. Fifty original research papers were obtained from a systematic search of the peer-reviewed literature. Results from a vote-counting analysis indicated that, in the majority of studies, pest abundance was significantly reduced in intercropping systems compared with pure stands. However, the occurrence of their natural enemies as well as predation and parasitism rates were not significantly increased. Nevertheless, other practices could be combined with intercropping to favour natural enemies and enhance pest control. Dispersal of viruses is intimately tied to their vectors. Aphids are known to invest in costly antipredator behavior when perceiving cues of predators. Before presenting the results and the answers to the previous questions, a brief research was conducted in order to have an overview of the intercropping on the spread of aphids, to assess the potential impact of intercropping systems attracting natural enemies on the virus transmission. We studied aphid antipredator behavior in intercropping with wheat-broad bean (Vicia faba L.) as a model. The bird cherry-oat aphid, Rhopalosiphum padi Linnaeus, is an important vector of the barley yellow dwarf virus. The effects of two natural aphid enemies, adult and larvae of the seven-spot ladybeetle, Coccinella septempunctata Linneaus, on R. padi dispersion was studied under laboratory conditions. Results show that in receptor lines (other lines than the source one), two hours after the experiment started, aphids were more abundant in monoculture than intercropping in the presence of ladybeetle adults and larvae and after 24 hours, it was still the case in the presence of predatory larvae. These results might be explained by the non-host plant chemical cues and the physical barrier that was broad-bean plants confusing R. padi when searching for their host plants after being dropped from wheat by predators. After make sure that the intercropping can reduce the dispersal of aphids in the presence of predators, in fine potentially limiting virus dispersal, especially shortly after aphids colonize plants. Then we try to solve how to increase the number of natural enemies of intercropping in Belgium and China. Semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining semiochemical and intercropping can be an interesting way to maximize pest control. In Belgium, a two-year setup involving wheat–pea strip intercropping combined with the release of E-β-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repell aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with intercropping. The abundance of aphids was significantly decreased, hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of aphids-parasitism rate was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. We also tested the combining in China and the experiments were set-up: wheat-pea strip intercropping solely, intercropping combined with the release of EBF, and intercropping combined with the release of MeSA, each treatment repeated three times. The total number of aphids throughout the growing season was significantly decreased in treatments with releases of semiochemicals compared to intercropping solely. The effect was stronger with MeSA than with EBF on the control of R. padi, and hoverflies and lacewings were twice more numerous in MeSA. All the results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides Dispersal of viruses is intimately tied to their vectors. Aphids are known to invest in costly antipredator behavior when perceiving cues of predators. Before presenting the results and the answers to the previous questions, a brief research was conducted in order to have an overview of the intercropping on the spread of aphids, to assess the potential impact of intercropping systems attracting natural enemies on the virus transmission. We studied aphid antipredator behavior in intercropping with wheat-broad bean (Vicia faba L.) as a model. The bird cherry-oat aphid, Rhopalosiphum padi Linnaeus, is an important vector of the barley yellow dwarf virus. The effects of two natural aphid enemies, adult and larvae of the seven-spot ladybeetle, Coccinella septempunctata Linneaus, on R. padi dispersion was studied under laboratory conditions. Results show that the total number of aphids was higher in intercropping than monoculture in treatments without ladybeetles, while the contrary was observed in the presence of ladybeetle larvae. These results might be explained by the non-host plant chemical cues and the physical barrier that was broad-bean plants confusing R. padi when searching for their host plants after being dropped from wheat by predators (i.e. associational resistance). After make sure that the intercropping can reduce the dispersal of aphids in the presence of predators, in fine potentially limiting virus dispersal, especially shortly after aphids colonize plants. Next step will be to solve how to increase the number of natural enemies of intercropping in Belgium and China. Semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining semiochemical and intercropping can be an interesting way to maximize pest control. In Belgium, a two-year setup involving wheat–pea strip intercropping combined with the release of E-β-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repell aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with intercropping. The abundance of aphids was significantly decreased, hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of aphids-parasitism rate was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. We also tested the combining in China and the experiments were set-up: wheat-pea strip intercropping solely, intercropping combined with the release of EBF, and intercropping combined with the release of MeSA, each treatment repeated three times. The total number of aphids throughout the growing season was significantly decreased in treatments with releases of semiochemicals compared to intercropping solely. The effect was stronger with MeSA than with EBF on the control of R. padi, and hoverflies and lacewings were twice more numerous in MeSA. All these results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides. [less ▲]

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See detailDevelopment of inversion techniques in Asteroseismology
Buldgen, Gaël ULiege

Doctoral thesis (2017)

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See detailAdvanced data processing for high-contrast imaging - Pushing exoplanet direct detection limits with machine learning
Gómez González, Carlos ULiege

Doctoral thesis (2017)

Since ancient times, mankind has wondered whether other solar systems exist around other stars somewhere in the Universe. It took many centuries to finally prove the existence of extra-solar planetary ... [more ▼]

Since ancient times, mankind has wondered whether other solar systems exist around other stars somewhere in the Universe. It took many centuries to finally prove the existence of extra-solar planetary systems. Nowadays, more than 3500 exoplanets have been discovered, mostly thanks to indirect detection methods. Indeed, the task of directly detecting exoplanets through high-contrast imaging (HCI) is a formidable challenge, and has only been enabled in the last decade thanks to advances in instrumentation and dedicated image processing algorithms. This last component of the exoplanet direct imaging pipeline is what ultimately pushes the detection limits and sensitivity of HCI instruments and survey campaigns. Unfortunately, the HCI community has been slow in adopting the latest developments in data management and machine learning for analyzing the increasing amount of available data. This dissertation is an attempt to fill in this very gap, and develops at the interface of computer science, machine learning, statistics, and astrophysics. This work contributes to the field of data processing for HCI in two main ways. On one hand, I have developed an open source \texttt{Python} library for taking HCI data from the raw state up to the characterization of companions. It implements state-of-the-art approaches and is positioning itself as one of the de facto software solutions for building HCI pipelines. I have also participated to the critical analysis of data from different first and second generation HCI instruments. On the other hand, I have approached the task of exoplanet detection in angular differential imaging sequences from a computer vision and machine learning perspective. This interdisciplinary work has led to novel algorithmic solutions, extending unsupervised learning techniques widely used in HCI and proposing advanced supervised learning approaches based on cutting-edge deep learning models. My novel algorithms have been presented using a robust performance assessment framework to produce large comparative performance studies. These studies show the improved sensitivity vs specificity trade-off of the proposed supervised detection approach. The proposed algorithms bring the possibility of re-processing existing HCI databases to maximize their scientific return and potentially improve the demographics of directly imaged exoplanets. [less ▲]

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See detailEconomic Development and Structural Change
Van Neuss, Leif ULiege

Doctoral thesis (2017)

This doctoral dissertation contributes to the understanding of structural change, often defined as the process of reallocation of economic activity and resources across the three broad sectors agriculture ... [more ▼]

This doctoral dissertation contributes to the understanding of structural change, often defined as the process of reallocation of economic activity and resources across the three broad sectors agriculture (primary sector), manufacturing (secondary sector) and services (tertiary sector). Increasingly connected to the study of modern growth, the analysis of structural change has known an important revival over recent decades, due in part to the economic concerns associated with the movement of deindustrialization that has particularly affected the world’s most economically successful countries since the last third of the 20th century. These concerns have indeed fed many discussions on the causes and consequences of structural change, as well as on the role of policy instruments in driving and accompanying the inter-sectoral reallocation of activity. The first part of the thesis gets particularly interested in the driving forces behind the process of structural change. It begins by placing structural change in a very long historical perspective, notably shedding light on the factors that contributed to the emergence of the Industrial Revolution, an event characterized by the acceleration of structural change and traditionally considered as a turning point in the history of mankind because it eventually brought about modernity. It then analyzes the main causes of structural change in market economies, putting a particular emphasis on two mechanisms of structural change that have been largely overlooked in the recent multi-sector growth literature: changes in input-output (sectoral) linkages and changes in comparative advantage via globalization and trade. With respect to trade, an empirical analysis reveals that global exchanges have the potential to influence significantly and substantially a country’s sectoral patterns of employment, and that the estimated contribution of trade, especially of trade with developing countries, to recent structural change (deindustrialization) in affluent countries may be revised upwards when resorting to better-suited indicators of trade in manufactures. The second part of this doctoral thesis deals more with the economic effects of structural change. In particular, it proposes a new shift-share method, which is an accounting method aimed at computing the impact of the economic structure - or structural change - on a territory’s economic performance. By way of illustration, it provides an application to manufacturing employment in the Belgian provinces between 1995 and 2007. [less ▲]

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See detailContributions to deep reinforcement learning and its applications in smartgrids
François-Lavet, Vincent ULiege

Doctoral thesis (2017)

Reinforcement learning and its extension with deep learning have led to a field of research called deep reinforcement learning. Applications of that research have recently shown the possibility to solve ... [more ▼]

Reinforcement learning and its extension with deep learning have led to a field of research called deep reinforcement learning. Applications of that research have recently shown the possibility to solve complex decision-making tasks that were previously believed extremely difficult for a computer. Yet, deep reinforcement learning requires caution and understanding of its inner mechanisms in order to be applied successfully in the different settings. As an introduction, we provide a general overview of the field of deep reinforcement learning. In the first part of this thesis, we provide an analysis of reinforcement learning in the particular setting of a limited amount of data and in the general context of partial observability. In this setting, we focus on the tradeoff between asymptotic bias (suboptimality with unlimited data) and overfitting (additional suboptimality due to limited data), and theoretically show that while potentially increasing the asymptotic bias, a smaller state representation decreases the risk of overfitting. An original theoretical contribution relies on expressing the quality of a state representation by bounding $L_1$ error terms of the associated belief states. We also discuss and empirically illustrate the role of other parameters to optimize the bias-overfitting tradeoff: the function approximator (in particular deep learning) and the discount factor. In addition, we investigate the specific case of the discount factor in the deep reinforcement learning setting case where additional data can be gathered through learning. In the second part of this thesis, we focus on a smartgrids application that falls in the context of a partially observable problem and where a limited amount of data is available (as studied in the first part of the thesis). We consider the case of microgrids featuring photovoltaic panels (PV) associated with both long-term (hydrogen) and short-term (batteries) storage devices. We propose a novel formalization of the problem of building and operating microgrids interacting with their surrounding environment. In the deterministic assumption, we show how to optimally operate and size microgrids using linear programming techniques. We then show how to use deep reinforcement learning to solve the operation of microgrids under uncertainty where, at every time-step, the uncertainty comes from the lack of knowledge about future electricity consumption and weather dependent PV production. [less ▲]

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See detailIdentification et analyse fonctionnelle de nouveaux variants d’épissage du CD46 des bovidés, le (co)-récepteur du virus BVD/MD
Alzamel, Nidal ULiege

Doctoral thesis (2017)

The pestivirus bovine viral diarrhea virus (BVDV) is known to bind to the CD46 molecule, which subsequently promotes entry of the virus. Mapping of the BVD-virion-binding site has shown that two peptides ... [more ▼]

The pestivirus bovine viral diarrhea virus (BVDV) is known to bind to the CD46 molecule, which subsequently promotes entry of the virus. Mapping of the BVD-virion-binding site has shown that two peptides, 66EQIV69 and 82GQVLAL87, located on antiparallel beta sheets in the most distal complement control protein module (CCP1), provide the attachment platform. In the present study, we reveal new CD46-encoding transcripts that are predicted to encode CCP1-containing soluble forms. Further, we show that the serum of most adult cattle contains soluble CD46 (sCD46) and that a recombinant soluble isoform neutralizes BVDV infectivity in an in vitro assay. We have then established an ELISA for determination of plasma sCD46 in a large cohort of animals. Overall, serum sCD46 amounts to 8 ± 18 ng/mL (mean ± SD, n = 543), with a IC [95-105] ranging from 6,4 to 9,8 ng/mL and extreme values between 0 and 178 ng/mL. We found that sCD46 is not detectable in fetal and neonatal sera and that its plasma concentration increases progressively up to adulthood. We also detected high- and low-sCD46 performers and show that this phenotype does not depend of environment. As modern rearing techniques make it possible to disseminate genetically-determined phenotypes very quickly in a population, a large-scale study examining whether high-sCD46 animals provide epidemiological protection against BVDV infection and transmission should be undertaken [less ▲]

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See detailAdaptive capacity assessment of damselfishes (Pomacentridae)
Gajdzik, Laura ULiege

Doctoral thesis (2017)

Assessing the multiple facets of adaptive capacity is a core issue as it reflects species' ability to cope with variations in environmental conditions. Within the threatened coral reefs, the Pomacentridae ... [more ▼]

Assessing the multiple facets of adaptive capacity is a core issue as it reflects species' ability to cope with variations in environmental conditions. Within the threatened coral reefs, the Pomacentridae (damselfishes) represent a very suitable model to undertake such issue. Damselfishes are one of the most ecologically dominant reef fish families whose lineages repeatedly radiated across convergent trophic strategies. These strategies comprise (1) pelagic feeders (mainly picking zooplankton in the water column), (2) benthic feeders (essentially feeding on algae and vagile invertebrates on the benthos) and (3) an intermediate group (foraging in the entire bentho–pelagic compartment). To date, most studies compared the degree of vulnerability between specialists and generalists because the first ones are thought to have a higher risk of extinction. The tripartite trophic guild system in Pomacentridae provides the opportunity to step out of the binary "specialist–generalist" classification and to robustly grasp the adaptive capacity by focusing on fundamental units in assemblages. In the present thesis, I estimated the ecology of damselfishes by quantifying their eco–functional diversity (including trophic, habitat and behavioural diversity and also the ecosystem functions they performed) and by gauging their abiotic (i.e. species–environment relationship) and biotic (i.e species–species relationship) interactions. Ecological results revealed (a) the systematic presence of the three main trophic guilds in each assemblage, and (b) a consistent pattern of species eco–functional niches that are highly differentiated and evenly distributed in eco–functional spaces of similar size, but they provided (c) limited support for any degree of trophic plasticity (i.e. little evidence for any geographic variation in the diet of widespread species). The trophic guilds were also functionally dissimilar and displayed different levels of functional diversity. The intermediate group was the least functionally diverse guild with the lowest functional redundancy, while opposite findings were found for the pelagic–feeding guild. Then, I quantified the genetic diversity, which varied among trophic guilds and was associated with variation in their trophic ecology and habitat–behavioural traits (e.g. pelagic feeders have the lowest genetic and ecological diversity). Using a phylogenetic framework, I found that functional traits were evolutionarily labile and accumulated at a similar rate within the three trophic guilds. Transition rates among guilds were also biased, suggesting differences in the evolvability. The evaluation of all of these components indicated that some processes occurring at an "ecological" timescale and others at an "evolutionary" timescale had concordant effects (e.g. the coupling between levels of genetic and ecological diversity supported by the evolvability result for the intermediate group), although sometimes one type of process had more important effects (e.g. the principle of competitive exclusion probably shaped the high functional diversity of pelagic feeders). Overall, I demonstrated that the adaptive capacity of Pomacentridae is bounded and that trophic guilds are not equal in the face of environmental changes. The case of pelagic feeders illustrates a scenario wherein evolution and the right environmental conditions led to the success of a given group, but their persistence may be jeopardized by a low genetic diversity. The two other guilds possess more intrinsic assets (e.g. less restricted habitat and dietary requirements) to adapt. Given the uncertainty regarding the pace at which evolutionary processes will occur and the potential imperilment of evolvability to act as a source of future diversity, the ability to diversify along many niche axes associated with broad intrinsic characteristics (i.e. higher genetic diversity) may help organisms to sustain themselves in a long–term perspective and to maintain more ecosystem functions. [less ▲]

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See detailMagneto-optical investigation of superconducting hybrid structures
Brisbois, Jérémy ULiege

Doctoral thesis (2017)

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See detailThe Cyanobacterial Biota of Polar Regions: a Molecular Approach
Stelmach Pessi, Igor ULiege

Doctoral thesis (2017)

Cyanobacteria are major components of Polar ecosystems. They comprise a considerable amount of the total biomass, are the main primary producers, and play important roles in the initial development of ... [more ▼]

Cyanobacteria are major components of Polar ecosystems. They comprise a considerable amount of the total biomass, are the main primary producers, and play important roles in the initial development of terrestrial and aquatic habitats. Although the cyanobacterial diversity in the Polar Regions has been well studied, research has been mostly limited to traditional methods such as microscopy, culturing, and Sanger-based molecular ecology approaches. High-troughput sequencing (HTS) has revolutionized our knowledge of microbial diversity and distribution, but a thorough investigation of polar cyanobacterial communities using HTS has not yet been performed. As a result, knowledge of the distributional patterns of polar cyanobacterial communities and the mechanisms underlying their structure is fragmentary. In this thesis, we applied the HTS approach to investigate the diversity and distributional patterns of cyanobacteria in a range of polar habitats. The main goals were: 1. To evaluate the use of HTS as a tool for assessing the cyanobacterial diversity in polar environments, including an assessment of different bioinformatics pipelines and the improvement represented by HTS in comparison to traditional methods; 2. To assess the spatial patterns of cyanobacterial communities across polar environments and the environmental factors shaping cyanobacterial community composition; 3. Tho study the successional dynamics of cyanobacterial communities following the colonization of recently deglaciated habitats. Due to its higher analytical depth, HTS was proven a valuable tool for the study of the cyanobacterial biota of Polar Regions. Nevertheless, the analysis of artificial communities highlighted the importance of strict bioinformatics control of HTS reads, as PCR and sequencing errors might bias the observed structure of the communities. Given the strict bioinformatics workflow applied, our results suggest a previously undetected polar cyanobacterial rare biosphere. On one side, the HTS approach revealed that microbial mat and biological soil crust (BSCs) across different Antarctic and Svalbard (High Arctic) regions are somewhat homogeneous, being dominated by filamentous cyanobacteria from the orders Pseudanabaenales and Oscillatoriales. At the phylotype level (97.5% similarity threshold), on the other hand, cyanobacterial communities were highly variable along environmental gradients within and between habitats. A study of benthic mat communities in Antarctic lakes revealed cyanobacterial communities highly structured by lake conductivity, and comparable compositions in lakes from distant Antarctic regions. In a study of BSC communities in four nunataks and mountain ridges in the Sør Rondane Mountains (Dronning Maud Land), highly dissimilar communities were observed between locations. Finally, two studies of BSC communities in Petunia Bay (Svalbard) revealed a marked, linear cyanobacterial community turnover along gradients of soil development. Altogether, the results obtained in the present thesis show that HTS is a powerful yet underused tool for the study of cyanobacterial diversity, not only in Polar Regions, but also on a global scale. This can be attributed to the very high sequencing depth achieved by HTS, which provides more robust assessments of community turnover and with a stronger statistical support than Sanger- based molecular ecology approaches. [less ▲]

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See detailétude fonctionnelle des facteurs d’épissage SR (Ser/Arg-rich) au cours du développement embryonnaire de Danio rerio.
Joris, Marine ULiege

Doctoral thesis (2017)

Ser/Arg-rich (SR) proteins constitute a phylogenetically conserved family of RNA binding proteins characterized by one or two RNA-recognition motifs (RRMs) at the N-terminus and a C-terminal domain ... [more ▼]

Ser/Arg-rich (SR) proteins constitute a phylogenetically conserved family of RNA binding proteins characterized by one or two RNA-recognition motifs (RRMs) at the N-terminus and a C-terminal domain enriched in Ser/Arg dipeptides. They are important regulators of constitutive and alternative splicing. Moreover, SR proteins are involved in many other aspects of RNA metabolism, including transcription, non-sense mediated decay, mRNA export, translational control as well as maintenance of genome stability. While the roles of SR splicing factors have been widely studied at a molecular level, their functions during animal cell differentiation and development are still largely undetermined. In this study, we decided to take advantage of the vertebrate model organism Danio rerio (zebrafish) to investigate SR protein functions by using molecular and genetic approaches. Fifteen zebrafish SR genes were identified belonging to the three subfamilies of SR proteins [SRSF1 (1RRM and 1 pseudo-RRM), SRSF2 (1RRM) and SRSF7 (1RRM +1ZnK)] initially described in humans. The current PhD thesis aimed to study of four of them, Srsfs5a, Srsf9, Srsfs7 and Srsf2b. We first determined the expression pattern of all SR genes by in situ hybridization at 24, 48 and 72 hours post-fertilization. This analysis revealed an ubiquitous expression pattern for SR genes, however pointing a higher expression in the brain and in the eyes. We next performed “knock-down” experiments using morpholinos (MOs) microinjection to determine SR gene functions. One splicing MO, designed to target srsf5a (sMOsrsf5a) showed an interesting phenotype that coincides with the expression pattern of the gene in the eyes. As none of the four other MOs used to target srsf5a could confirm the phenotype, we generated stable knockout mutant lines using TALEN and CRISPR/Cas9. Interestingly, the corresponding homozygous mutants did not display any phenotypic traits. These inconsistencies were attributed to a possible genetic compensation mechanism in mutants, but also to an underestimated large number of inadvertent morpholino RNA targets. Indeed, we uncovered that only 11 consecutive bases complementary to the 25 MO bases are sufficient for binding and subsequent blocking of splice sites, suggesting that the sMOsrsf5a induced phenotype was not due to the inactivation of this unique, specific gene. In addition, we observed that sMOsrsf5a secondary targets can be slightly reduced by increasing embryos growth temperature after microinjection. Our study contributes to the debate concerning MO specificity, efficacy and the number of unknown targeted sequences.   [less ▲]

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See detailValence des verbes et interdépendances entre lexique et syntaxe en kirundi
Tuyubahe, Pascal ULiege

Doctoral thesis (2017)

Ce travail de recherche a pour objet de décrire des phénomènes lexicaux et syntaxiques du kirundi peu examinés précédemment. Il est subdivisé en deux principales parties : la première partie est consacrée ... [more ▼]

Ce travail de recherche a pour objet de décrire des phénomènes lexicaux et syntaxiques du kirundi peu examinés précédemment. Il est subdivisé en deux principales parties : la première partie est consacrée à l’élaboration d’un lexique valenciel des verbes avec un ou plusieurs compléments, en prenant comme points de départ la liste de lexèmes de de Samie (2008) ainsi que le dictionnaire rundi-français de Rodegem (1970). Il s’avère que beaucoup de verbes peuvent apparaître dans différents schémas de construction, ce qui implique plusieurs unités lexicales pour ces verbes dans le lexique valenciel. La deuxième partie, composée de sept chapitres, consiste en la recherche de généralisations pouvant être faites à partir de ce lexique ; ces généralisations reposant sur une large base empirique, elles sont assez fréquemment accompagnées d’exceptions. Le chapitre 1 concerne le comportement syntaxique des groupes nominaux et groupes prépositionnels dans la valence des verbes et leur caractérisation par des tests; il y est question des objets directs, des objets prépositionnels, des circonstants et des attributs. Un chapitre est consacré au passif impersonnel (chapitre 2) car cette construction fournit une justification purement empirique à la catégorie « objet prépositionnel » en kirundi, permettant de distinguer les objets prépositionnels (locatif ou non) des autres compléments (y compris les circonstants valenciels de lieu). Le chapitre 3 montre l’importance quantitative des objets directs par rapport aux autres objets du lexique valenciel des verbes en kirundi et montre comment cette importance est encore accrue par l’existence en kirundi d’objets directs non valenciels, en particulier les objets introduits par l’intermédiaire d’un suffixe verbal (suffixe applicatif -ir- ou suffixe causatif -i- ou -iish-) et les possesseurs inaliénables introduits sans intermédiaire. Après avoir fait une présentation générale des temps et aspects et de la concordance des temps en kirundi (chapitre 4), les chapitres 5, 6 et 7 montrent comment cela se manifeste dans les propositions subordonnées valencielles et les propositions avec auxiliaire, en distinguant celles qui ont un verbe conjugué et celles qui ont un infinitif. Les conclusions générales sont suivies des propositions prospectives permettant d’effectuer des recherches approfondies en vue de compléter le lexique valenciel, d’une part et, d’autre part, de déterminer les conditions d’emploi des suffixes causatifs -i- et -iish-. [less ▲]

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See detailFunctional diversity and mowing regime of flower strips as tools to support pollinators and to suppress weeds
Uyttenbroeck, Roel ULiege

Doctoral thesis (2017)

Intensification of agriculture during past decades is one of the causes of biodiversity declines. Ecological intensification has been proposed as a more sustainable alternative of intensive agriculture ... [more ▼]

Intensification of agriculture during past decades is one of the causes of biodiversity declines. Ecological intensification has been proposed as a more sustainable alternative of intensive agriculture that should be able to fulfill worldwide demands of food, by optimizing ecosystem functions and services and reducing environmental impacts. One way to restore ecosystem functions and services in arable fields is creating flower strips in field margins. These flower strips enable wild plant communities to thrive and provide food and shelter to associated fauna. It is often suggested that increasing plant functional diversity could be a tool to optimize ecosystem functioning and ecosystem service delivery, and it could thus be a goal for the creation and management of flower strips. An example of ecosystem functioning studied in this manuscript, is the mutualistic interaction between plants and pollinators. To convince European farmers to implement flower strips, they are included in the subsidized Agri-Environment Schemes. However, there exists no clear appraisal of the pros and cons of flower strips for farmers. By systematically reviewing the literature for pros and cons, we found that most studies concerned agronomical and ecological processes related to flower strips, but few or no studies were dedicated to the social and economic aspects. Furthermore, pollination appears to be an important pro, and weed infestation a possible con, depending on flower strip creation and management. We focused on these two examples in the further study. We investigated (1) whether the increase of plant functional diversity can be used as tool to optimize flower strips for pollinators, (2) whether forb competition and adapting timing and frequency of mowing can be used as tools to limit weeds in flower strips, and (3) whether flower strips perform equally in supporting pollinators as the natural habitat for which they are thought to be a surrogate. To use functional diversity as a tool to optimize flower strips for pollinators, we first tested whether it is possible to create a flower strip with a desired functional diversity level. We sew experimental flower strips with increasing functional diversity, based on visual, morphological and phenological flower traits and surveyed the vegetation composition the first year after sowing. The sown gradient of functional diversity was present, but with lower absolute values due to unequal cover of sown species and due to the presence of spontaneous species. To test the effect on pollinator support, we monitored the plant-pollinator networks in the experimental strips during two years. In contrast to our expectations, pollinator species richness and evenness were not influenced by functional diversity, and increasing functional diversity even resulted in lower flower visitation rates. To investigate the effect of forb competition and timing and frequency of mowing on weed infestation, we created experimental flower strips either with grass and forb species in the seed mixture, either with only grass species. Three different mowing regimes were applied: summer mowing, autumn mowing and mowing both in summer and autumn. The cover of important weed, Cirsium arvense, was limited by adding forbs to the seed mixture and by mowing in summer or in summer and autumn. At last, by surveying plant-pollinator networks in perennial flower strips and natural hay meadows in the same landscape context, we observed that both the plant and the pollinator communities differed between the flower strips and the meadows. Perennial flower strips can thus be considered as a complementary habitat in the landscape and not a hay meadow surrogate. This study suggests that it is possible to manipulate the vegetation as well as infestation by certain weeds in flower strips by adapting the seed mixture and the mowing regime. However, to promote pollinators in flower strips, increasing plant functional diversity appears not to be the key, and the abundance of certain attractive plant species can be more important. Moreover our results suggest that pollinators perceived a lower redundancy of functional plant trait values when functional diversity was higher, as they had more separate feeding niches (less visited flower species in common). Our results also suggest that there could be a trade-off between the increase of functional trait diversity and the floral resource abundance per niche or functional trait combination. With the results of the tested flower strip creation and management methods and their effect on pollinator support and weed infestation, farmers and administrations can try to create and manage flower strips with the desired balance between pros and cons, and researchers can try to refine these methods and test the effects on other pros and cons. [less ▲]

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See detailL'abandon de sanctuaires et le transfert de cultes en Grèce antique
Palamidis, Alaya ULiege

Doctoral thesis (2017)

Dans la Grèce antique, les sanctuaires anciens comme les sanctuaires nouvellement fondés étaient censés continuer à être fréquentés indéfiniment. Cependant, ce n’était pas le cas de tous les lieux de ... [more ▼]

Dans la Grèce antique, les sanctuaires anciens comme les sanctuaires nouvellement fondés étaient censés continuer à être fréquentés indéfiniment. Cependant, ce n’était pas le cas de tous les lieux de culte: certains pouvaient être abandonnés, de même que les divinités qui y étaient honorées, tandis que d’autres divinités continuaient à être honorées à un emplacement différent. Ce travail vise en premier lieu à analyser les sources littéraires, épigraphiques et surtout archéologiques qui nous renseignent sur des tels abandons de sanctuaires et transferts de cultes. L’étude de deux types de déplacements de population, les synécismes et les métécismes, au cours desquels de tels abandons et transferts sont documentés, permet par la suite de réfléchir notamment aux raisons qui expliquent l’abandon de certains sanctuaires plutôt que d’autres. L’analyse des sources disponibles suggère que ni les abandons de sanctuaires, ni les transferts de culte n’étaient considérés comme la transgression d’une norme tacite ou orale et que ces phénomènes sont beaucoup plus courants que ce qui est généralement supposé. [less ▲]

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See detailAnalyse de l’effet de la température et du préférendum thermique sur les mécanismes du déterminisme sexuel et de la différenciation gonadique chez le poisson-chat Africain, Clarias gariepinus
Santi, Saïdou ULiege

Doctoral thesis (2017)

Les poissons constituent le groupe de vertébré le plus diversifié présentant des systèmes de déterminisme et de différenciation sexuels aussi divers que variés. Ces systèmes sont caractérisés par une ... [more ▼]

Les poissons constituent le groupe de vertébré le plus diversifié présentant des systèmes de déterminisme et de différenciation sexuels aussi divers que variés. Ces systèmes sont caractérisés par une grande labilité et sont influencés par des facteurs génétiques, physiologiques et environnementaux, ces derniers pouvant influencer à la fois, le déterminisme du sexe et la différenciation des gonades. Le poisson chat africain Clarias gariepinus, une espèce présentant un déterminisme sexuel à homogamétie femelle (XX/XY), n’a fait l’objet que de peu d’études sur le rôle des facteurs environnementaux sur la détermination et différenciation sexuelle. Nous avons choisi d’étudier le rôle de la température dans ces mécanismes par trois approches complémentaires. Une approche histologique nous a permis de mettre en évidence qu’une haute température (36°C) influence la différenciation gonadique très précocement, de 6 à 8 jours post-l’éclosion (jpe), en entrainant fréquemment une déviation significative du sexe-ratio vers les mâles. La précocité de la thermosensibilité, avant le premier signe de différenciation histologique des gonades, suggère que la haute température pourrait agir sur d’autres cibles que les gonades elles-mêmes, telles que les cellules germinales primordiales, ou le cerveau, pour induire une masculinisation de la progéniture. Nous avons de plus mis en évidence que la distribution du sexe-ratio dans les différentes populations était très variable, suggérant le rôle de déterminants génétiques mineurs dans le processus de déterminisme du sexe chez le poisson-chat africain. Globalement, nous ces résultats sont caractéristiques de la présence d’une inversion du sexe température-induite (TISR) ainsi que des traits d’un déterminisme génétique polyfactoriel du sexe chez le poisson-chat africain. Une approche physiologique et génétique nous a permis de mettre en évidence que globalement, la haute température n’influence ni les profils des concentrations des trois principaux stéroïdes sexuels (17β-œstradiol, 11-cétotestostérone et testostérone), ni les expressions des gènes cyp19a1b et dmrt1 généralement impliqués dans ces mécanismes. Toutefois, les progénitures très thermosensibles présentent des expressions plus faibles du gène cyp19a1b six jours après l’exposition à la haute température. De même, les plus fortes expressions du gène de dmrt1 ont été observées chez les individus contrôles. Ces résultats renforcent notre hypothèse de sexualisation précoce du cerveau dans le processus de masculinisation température-induite. Des études supplémentaires sur l’action de la haute température sur la prolifération de cellules germinales primordiales, ainsi que d’autres processus comme l’activité ou la méthylation des gènes de la différenciation sexuelle doivent être envisagées. Une approche comportementale nous a finalement permis de mettre en évidence que les juvéniles indifférenciés présentent un comportement migratoire vers les hautes températures lorsqu’ils sont placés dans un continuum thermique (28,0 – 32,0 – 36,0°C), associés à une masculinisation de 50,0 à 82,5%, soulevant la question suivante : le déplacement à hautes températures confère-t-il des avantages particuliers aux individus ou à la population en milieu naturel ? Cette thermosensibilité contribuerait à augmenter la proportion de femelles dans la population, lorsque les pseudomales (XX) vont se reproduire avec des femelles XX. L’augmentation de la capacité reproductive de la population, résultante, pourrait permettre un accroissement de l’effectifs des larves et juvéniles, pour rétablir l’équilibre du sexe-ratio lors du retour à des conditions environnementales normales. Globalement nous pouvons conclure que Clarias gariepinus présente un TISR avec une implication des déterminants génétiques mineurs dans la différenciation du sexe. La thermolabilité pourrait conférer un avantage adaptatif à l’espèce, mais l’adaptabilité d’un tel processus d’établissement du sexe reste une question très ouverte. [less ▲]

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See detailFirst-principles study of tungsten trioxide: Structural properties and polaron formation
Hamdi, Hanen ULiege

Doctoral thesis (2017)

Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO3. Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which ... [more ▼]

Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO3. Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which provides very good agreement with experimental data. We show that the hypothetical high-symmetry cubic reference structure combines several ferroelectric and antiferrodistortive (antipolar cation motions, rotations and tilts of oxygen octahedra) structural instabilities. Although the ferroelectric instability is the largest, the instability related to antipolar W motions combines with those associated to oxygen rotations and tilts to produce the biggest energy reduction, yielding a P2_1/c ground state. This non-polar P2_1/c phase is only different from the experimentally reported Pc ground state by the absence of a very tiny additional ferroelectric distortion. The calculations performed on a stoichiometric compound so suggest that the low temperature phase of WO3 is not intrinsically ferroelectric and that the {experimentally observed} ferroelectric character might arise from extrinsic defects such as oxygen vacancies. Independently, we also identify never observed R3m and R3c ferroelectric metastable phases with large polarizations and low energies close to the P21/c ground state, which makes WO3 a potential antiferroelectric material. The relative stability of various phases is discussed in terms of the anharmonic couplings between different structural distortions, highlighting a very complex interplay. On the second hand, the addition of a single electron to the largest supercell of the monoclinic P21/c ground state of WO3 causes the development of a medium polaron inside of this material. We then study and characterize a medium polaron formation in WO3 from first-principles calculation. We show how the medium polaron in the supercell of WO3 can change its structural, electronic and dynamical properties. [less ▲]

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See detailNonlinear analysis of compliant deployable structures: modelling, simulation and experimental validation
Dewalque, Florence ULiege

Doctoral thesis (2017)

Compliant mechanisms are flexible components which can store elastic energy when deformed and then passively release it to produce a motion. Their scope of applications encompasses various domains from ... [more ▼]

Compliant mechanisms are flexible components which can store elastic energy when deformed and then passively release it to produce a motion. Their scope of applications encompasses various domains from robotic orthoses to microscopes and grippers. In this work, the developments focus on compliant mechanisms called tape springs used in deployable space structures. Tape springs, due to their autonomous deployment capacity from a compact folded configuration, their high stiffness in the deployed equilibrium state and their simplicity of integration, represent efficient alternatives to common motorised hinges for space applications. Thus, they are currently used to deploy appendices on satellites such as solar panels or telescopes and are considered as valuable components in the design of future applications such as solar sails, deployable optics and inflatable structures. However, their structural behaviour is highly nonlinear and quite sensitive to the design parameters and to the various constraints encountered on Earth and in a space environment. The objective of this thesis is thus to develop validated high-fidelity dynamic models of tape springs which can be used to support the design process. The methodology involves the development of advanced finite element models and experimental tests based on an original set-up. First, a quasi-static model based on shell finite elements is established and used to investigate the nonlinear response of tape springs as well as the influence of various geometric parameters. This model is then exploited for the design of tape springs deploying a reflector based on an automatic optimisation procedure. The study is further extended to dynamic analyses, which are characterised by a self-locking of the tape springs in their final deployed configuration. In order to accurately capture these phenomena, the importance of a suitable representation of the physical structural dissipation in the model is demonstrated and, for metallic tape springs, a Kelvin-Voigt model is retained. An experimental set-up is then designed in order to validate the model and its capacity to represent the nonlinear phenomena inherent to tape springs which occur during quasi-static and dynamic tests. The experimental data are acquired by the means of an innovative 3D motion analysis system and a force plate. The reproducibility of the tests is assessed and a procedure, involving several elementary tests, is proposed to identify the parameters of the finite element model, in particular, the structural damping. In the end, a fair correlation between the experimental and numerical results is achieved. The proposed methodology, which relies on numerical and experimental methods, thus leads to a dynamic model of tape springs which can be used to predict their behaviour in various conditions. [less ▲]

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See detailMultifunctional Polyelectrolytes Bearing Pendant Catechol / Quinone for Energy and Environmental Applications
Patil, Nagaraj ULiege

Doctoral thesis (2017)

The discovery of 3,4-dihydroxyphenyl-L-alanine (L-DOPA), a catechol-functionalized amino acid as major component in mussel adhesion proteins, has triggered enormous interest in mussel-mimetic adhesives ... [more ▼]

The discovery of 3,4-dihydroxyphenyl-L-alanine (L-DOPA), a catechol-functionalized amino acid as major component in mussel adhesion proteins, has triggered enormous interest in mussel-mimetic adhesives. The design of innovative bioinspired polymers-containing catechols has rapidly gained widespread utility in the (bio)material field, ascribed to the versatility of the catechol chemistry that allows anchoring (bio)polymers, biomolecules, nanoparticles (metals and metal oxides) and other compounds onto almost any kind of surfaces without any pre-treatment. Amongst the various synthetic protocols to incorporate catechol functionalities into (bio)polymers, the radical polymerization of catechol-bearing vinyl monomers in their protected form has proven to be a versatile technique to impart intrinsic physico–chemical properties of the catechol pendants to polymers after appropriate deprotection. Importantly, the scope of applications of catechol-bearing polymers can potentially be drastically increased by developing controlled radical polymerization (CRP) techniques of their protected vinyl monomers. Indeed, these techniques will enable to precisely design the polymer with the appropriate structure, molar mass and functionality that fit at best the target application. When this thesis started in 2013, only very limited examples of functional catechol-bearing polymers prepared by CRP were reported. The aim of this PhD thesis was to develop well-defined innovative catechol-containing (co)polymers that find applications in energy storage and environmental fields by employing function-oriented macromolecular engineering approaches. In this work, numerous catechol-protected monomers have been prepared and their CRP investigated to afford well-defined (co)polymers with controlled and tunable molar masses, compositions, functionalities, and architectures (homopolymers, statistical and block copolymers). The potential of these innovative catechol-containing (co)polymers was then explored for applications in energy storage (as active-material in lithium-ion half-cells) and environment (as protein fouling/antifouling coatings). [less ▲]

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See detailSearch for the signatures of mass-exchange episodes in massive binaries
Raucq, Françoise ULiege

Doctoral thesis (2017)

Massive stars are known for their crucial role in our Universe, through their extreme stellar parameters, leading to a strong impact on their environment. However, there remain numbers of unanswered ... [more ▼]

Massive stars are known for their crucial role in our Universe, through their extreme stellar parameters, leading to a strong impact on their environment. However, there remain numbers of unanswered questions concerning the exact processes of their formation, their stability or the processes driving their strong stellar winds. In the context of this thesis work, we adress one of the most interesting of their peculiarities: their tendency to be part of binary of higher multiplicity systems. Whilst this multiplicity does help to solve some open issues by allowing us to study some of the fundamental properties of the stars, such as their minimum masses and radii as well as their stellar luminosities, it can also lead to interactions between the components of a system, which affect the subsequent evolution of the stars and give rise to additional open questions on the processes in place in such systems. Among the possible interactions taking place within close binary systems is the possibility of a transfer of mass and kinetic momentum through a Roche lobe overflow. This process has a huge impact on the subsequent evolution of both components and many aspects of this phenomenon are not well understood yet. The present work is devoted to the search for the signatures of such past mass-exchange episodes in a sample of four short-period massive multiple systems: HD 149404, LSS 3074, HD 17505 and HD 206267. We determined a new orbital solution for three of them. We then used phase-resolved spectroscopy to perform the spectral disentangling of the optical spectra of the components. The spectral disentangling is a mathematical tool which allows to separate the contributions of both components to the observed spectra of a system. We then analysed the reconstructed spectra with the CMFGEN atmosphere code to determine stellar parameters, such as the effective temperatures and surface gravities, and to constrain the surface chemical composition of each component. The first two parts of this dissertation are dedicated to the scientific background and the description of the numerical tools and methods used in this work. The third part presents our studies of the selected massive systems. We confirmed that the hypothesis of a past Roche lobe overflow episode is most plausible to explain the observed properties of the components of HD 149404. Photometric data permitted us to confirm that LSS 3074 is in an overcontact configuration, and a combined analysis with spectroscopy showed that the system has lost a significant fraction of its mass to its surroundings. We proposed several possible evolutionary pathways involving a Roche lobe overflow process to explain the current parameters of its components. We found no evidence of past mass-transfer episodes in the spectra of HD 17505 and showed that the current properties of its components can be explained by single star evolutionary models including rotational mixing. We found clues of binary interactions in the spectra of HD 206267, but suggested that the system did not experience a complete Roche lobe overflow episode at this stage of its evolution. [less ▲]

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See detailQuality evaluation of peach chips and anticancer activity of pectin extracted from chips dehydrated by explosion puffing drying
Lyu, Jian ULiege

Doctoral thesis (2017)

The objectives of this research are to discriminate the overall quality level of peach and nectarine chips prepared by explosion puffing drying (EPD), determine the changes of texture and water soluble ... [more ▼]

The objectives of this research are to discriminate the overall quality level of peach and nectarine chips prepared by explosion puffing drying (EPD), determine the changes of texture and water soluble pectin (WSP) during EPD processing and study the anticancer activity of WSP on malignant mesothelioma (MM). Principle component analysis (PCA), Analytic hierarchy process (AHP), K-mean cluster and Discriminant analysis (DA) are used to distinguish the overall quality level of peach and nectarine chips and get the characteristic evaluation indicators, which of them (e. g. rehydration ratio and expansion ratio) are corresponding to texture properties of dehydrated products. Additionally, biochemical changes of the cell wall (e. g. pectin) are also related to texture changes. The investigate on the changes of texture and WSP at different stages of EPD processing in which osmotic dehydration (OD) was used as the pretreatment, show that OD with the appropriated concentration can improve the texture quality of dried products. The drying processing causes the degradation and structure modification of WSP, which can induce apoptosis in MM cells. EPD technology can be carried out as a potential pathway on modification of pectin, which may contribute to the development of a potential therapy against MM. [less ▲]

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See detailRhétorique du détournement vidéoludique. Le cas de Pokémon
Barnabé, Fanny ULiege

Doctoral thesis (2017)

La présente recherche se situe au croisement de plusieurs traditions disciplinaires – les sciences du jeu, les études littéraires, la rhétorique, les cultural studies – et de plusieurs objets – le jeu, le ... [more ▼]

La présente recherche se situe au croisement de plusieurs traditions disciplinaires – les sciences du jeu, les études littéraires, la rhétorique, les cultural studies – et de plusieurs objets – le jeu, le détournement, les fanfictions, machinimas, speedruns, let’s plays et mods. Sans prétendre opérer ici leur synthèse ou leur conciliation, nous tenterons de dégager, entre ces différents domaines, de nouvelles ouvertures : nous montrerons, en circulant parmi eux, qu’ils sont pris dans des tensions, des dynamiques, des questionnements similaires et, surtout, centraux pour la compréhension de la culture populaire contemporaine. Plusieurs objectifs nous animent : définir le détournement et, à travers lui, éclairer sous un autre jour le fonctionnement du jeu ; développer un métadiscours à même de soutenir l’analyse des œuvres produites par les joueurs ; enfin, par la même occasion, défendre l’intérêt d’étudier de près ces œuvres amateurs, trop souvent délaissées par la recherche au profit des pratiques, et qui sont pourtant des épicentres essentiels autour desquels se développent les cultures ludiques. La poursuite de ces objectifs, toutefois, ne va pas sans soulever des questions complexes, qui traversent toute la thèse : quels parallèles et quelle frontière établir entre le détournement et le jeu ? Comment une œuvre est-elle reconnue, étiquetée, classée comme un détournement ? Qu’est-ce au juste qu’une œuvre dans un domaine où l’intertextualité, la reprise, la réinterprétation sont des normes ? Avec quels outils décrire les formes du détournement, et qu’ont en commun les genres disparates regroupés sous cette dénomination ? Nous traiterons ces diverses interrogations en deux temps. La première partie de la thèse, qui comporte deux sous-sections, en constituera le socle théorique : un premier chapitre y aborde les relations intimes entre jeu et détournement, tout en resituant notre recherche dans les différents champs qu’elle fait se croiser ; le second chapitre s’attache à la constitution d’un cadre métadiscursif inspiré de la rhétorique, visant à définir ce que pourraient être des « figures » du détournement vidéoludique. La deuxième partie, plus analytique, servira d’application au cadre précédemment construit, en montrant son utilité sur des études d’œuvres concrètes. Celles-ci sont réparties en trois grandes catégories : les détournements par le play (let’s plays, speedruns, tool-assisted speedruns et machinimas), les détournements du game (fanfictions et mods) et les recontextualisations (« Twitch plays… »). Par ailleurs, en guise de fil conducteur, toutes ces œuvres – de formes et de genres variés – auront pour point commun essentiel d’être dérivées d’un même univers fictionnel : celui de la licence Pokémon. [less ▲]

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See detailLes pathologies intestinales chirurgicales chez le cheval: activation neutrophilique, pronostic et complications postopératoires
Salciccia, Alexandra ULiege

Doctoral thesis (2017)

Postoperative complications after colic surgery in horses remain of major concern as they are associated with non-negligible mortality rates. Many of these postoperative complications have an important ... [more ▼]

Postoperative complications after colic surgery in horses remain of major concern as they are associated with non-negligible mortality rates. Many of these postoperative complications have an important inflammatory component involving leukocytes, and particularly neutrophils, which represent the majority of granulocytes. Activated neutrophils produce reactive oxygen species and release inflammatory mediators and oxidative and proteolytic enzymes such as myeloperoxidase and elastase, which in turn will exacerbate pre-existing tissue lesions. This cascade of events will lead to the systemic inflammatory response syndrome. In an effort to improve the understanding of the systemic inflammatory reaction that follows colic surgery in horses, we described the time-trends of blood leukocytes and granulocytes counts and plasma myeloperoxidase and elastase concentrations during the perioperative period. Globally, survivor horses presented curves of blood leukocytes and granulocytes counts evolution lower and curve of evolution of plasma myeloperoxidase concentrations higher than those of non-survivor horses. These findings confirm the major influence of the inflammatory reaction on patient survival and allowed us to determine a prognostic value of blood leukocytes counts, a parameter easily available and routinely used in the aftercare of horses undergoing a colic surgery. We showed that in our population, non-survivor horses were more likely to have at least one blood leukocyte count inferior or equal to 3.9×10³/mm³ between 28 and 60 hours after surgery than survivor horses. Our following research, based on clinical studies, were directly or indirectly related to 2 common postoperative complications: incisional complications and ileus. In a study evaluating more than 600 exploratory laparotomies for colic, we showed that short laparotomy incisions, partially closed with interrupted vertical mattress sutures on the linea alba, and protected and supported by an abdominal bandage applied before the recovery from anaesthesia were associated with relatively low incisional complication and infection rates. These rates were respectively 9,52% and 5,31% after a single laparotomy and respectively 33,33% and 26,67% after repeat laparotomy. Bandage related complications occurred rarely. Risk factors of an incisional complication or infection in our population were prolonged anaesthesia duration, performing an enterotomy and postoperative intravenous lidocaine administration. The knowledge of these elements will certainly contribute to reduce the incidence of these complications in the future. Transabdominal ultrasonography of the small intestine is frequently used to diagnose and monitor a postoperative ileus. In order to improve the interpretation of ultrasonographic images after surgery, we determined the influence of general anaesthesia on these images. Using a protocol including horses anaesthetised for non-abdominal surgeries, we showed that although anaesthesia induces a physiologic ileus of short duration, expressed by a decreased of borborygmi without abdominal discomfort, its effects on the ultrasonographic images of the small intestine consisted mainly of a temporary increase (less than 12 hours) of the jejunal visualisation and diameter (with most of the observations remaining in the normal range) without thickening of the intestinal wall. Therefore the effects of general anaesthesia on ultrasonographic images of the small intestine can be distinguished from those of a pathological process. Our last study, including sound horses revealed that lidocaine, a molecule frequently used for treatment of postoperative ileus, may have a mild hypotensive effect on the arterial blood pressure and a mild prokinetic effect on the duodenum. Nevertheless, these results, original about the hypotensive effect, and controverted about the prokinetic effect, need to be confirmed in longer and larger studies. Our work has allowed us to bring some new elements leading to the improvement of our understanding of inflammatory processes related to the neutrophilic activation during the perioperative period of colic horses. Despite the improvement of methods of prevention, detection and treatment of postoperative complications, prognoses after this type of surgery still need to be enhanced. It seems that a huge work remains to be done to precisely determine the effects of various treatments, such as lidocaine. Numerous perspectives appear in the search of new molecules aiming to reduce the inflammatory reaction and to prevent or treat postoperative complications of horses undergoing colic surgery. [less ▲]

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See detailStatistical analysis of areal quantities in the brain through permutation tests
Winkler, Anderson ULiege

Doctoral thesis (2017)

In this thesis we demonstrate that direct measurement and comparison across subjects of the surface area of the cerebral cortex at a fine scale is possible using mass conservative interpolation methods ... [more ▼]

In this thesis we demonstrate that direct measurement and comparison across subjects of the surface area of the cerebral cortex at a fine scale is possible using mass conservative interpolation methods. We present a framework for analyses of the cortical surface area, as well as for any other measurement distributed across the cortex that is areal by nature, including cortical gray matter volume. The method consists of the construction of a mesh representation of the cortex, registration to a common coordinate system and, crucially, interpolation using a pycnophylactic method. Statistical analysis of surface area is done with power-transformed data to address lognormality, and inference is done with permutation methods, which can provide exact control of false positives, making only weak assumptions about the data. We further report on results on approximate permutation methods that are more flexible with respect to the experimental design and nuisance variables, conducting detailed simulations to identify the best method for settings that are typical for imaging scenarios. We present a generic framework for permutation inference for complex general linear models (GLMs) when the errors are exchangeable and/or have a symmetric distribution, and show that, even in the presence of nuisance effects, these permutation inferences are powerful. We also demonstrate how the inference on GLM parameters, originally intended for independent data, can be used in certain special but useful cases in which independence is violated. Finally, we show how permutation methods can be applied to combination analyses such as those that include multiple imaging modalities, multiple data acquisitions of the same modality, or simply multiple hypotheses on the same data. For this, we use synchronised permutations, allowing flexibility to integrate imaging data with different spatial resolutions, surface and/or volume-based representations of the brain, including non-imaging data. For the problem of joint inference, we propose a modification of the Non-Parametric Combination (NPC) methodology, such that instead of a two-phase algorithm and large data storage requirements, the inference can be performed in a single phase, with more reasonable computational demands. We also evaluate various combining methods and identify those that provide the best control over error rate and power across. We show that one of these, the method of Tippett, provides a link between correction for the multiplicity of tests and their combination. [less ▲]

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See detailLANDSLIDE SUSCEPTIBILITY PREDICTION IN A MOUNTAINOUS CATCHMENT: THE NARANJO BASIN, WESTERN GUATEMALA
Estrada Orozco, Nick Kenner ULiege

Doctoral thesis (2017)

In tropical mountain areas, landslides triggered by heavy rainfall represent a natural hazard, especially where meteorological events such as tropical cyclones are recurrent. Rainfall-triggered landslides ... [more ▼]

In tropical mountain areas, landslides triggered by heavy rainfall represent a natural hazard, especially where meteorological events such as tropical cyclones are recurrent. Rainfall-triggered landslides may also increase in highly seismic active areas. This is the case of Guatemala, located in the Circum-Pacific Belt and between Pacific and Atlantic Oceans, sources of cyclonic events. Although Guatemala is a region where landslides are a widespread phenomenon, landslide inventories, maps and quantitative susceptibility assessments that are useful for land use planners and decision makers are hitherto non-existent. The aim of this research is to produce quantitative landslide susceptibility assessments, using logistic regression multivariate statistical method. The study area is a watershed located in the department of San Marcos (western Guatemala), impacted by a tropical storm event in October 2005. A total of 766 landslides were identified and mapped using orthoimages from 2005. Then, 99 landslides were mapped in 2011 based on field data. The main landslide type is shallow landslide (61 % in 2005), while 39 % of those landslides from 2005 evolved into debris flows. In total, susceptibility models using multivariate probabilistic approach were developed for shallow landslides, evaluating two different strategies for the sample size of non-landslides events and three different numbers of input variable in the models. Susceptibility models were developed for debris flows dataset and the union of both dataset (shallow and debris flows). The comparison of the models and the associated susceptibility maps highlighted 6 significant input variables that are associated with landslide occurences - elevation, slope, aspect, profile curvature, planform curvature and distance to roads. Performance comparisons of models were also carried out. To validate the performance of the model results, the ROC curve was used, as well as the four-fold and confusion matrix plots. A susceptibility map was generated to display the results of the models in terms of probability values. A proposal and discussion on the operational use of susceptibility maps where cutoff values can be chosen to define the lowest and highest landslide susceptibility were also made. These will help land use planners in decision-making and in implementing protective measures. [less ▲]

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See detailHistoire évolutive du complexe Afzelia Smith (Leguminosae - Caesalpinioideae) dans les écosystèmes forestiers et savanicoles en Afrique tropicale
Donkpegan, Segbedji ULiege

Doctoral thesis (2017)

The genus Afzelia Smith (Fabaceae, Caesalpinioideae) is known to have seven African tree species two of which are found in the Zambezian region, one is distributed in the Sudanian region and the four ... [more ▼]

The genus Afzelia Smith (Fabaceae, Caesalpinioideae) is known to have seven African tree species two of which are found in the Zambezian region, one is distributed in the Sudanian region and the four other are endemic to the Guineo-Congolian region. These taxa, of high commercial value, are difficult to identify. They are therefore marketed under the same "doussié" name. These difficulties of distinction can prove detrimental to the sustainable management of populations. The aim of this doctoral thesis is to characterize the evolutionary history of the Afzelia genus. More specifically, this study aims to: (i) evaluate the level of morphological divergences within the Afzelia genus and describe the phylogenetic relationships in order to quantify the reproductive isolation between taxa by highlighting the role of past climate change and / or ecological gradients in the speciation of the genus; (ii) proceed to an analysis of the spatial genetic diversity and structure of Afzelia spp.; (iii) identify and describe ecological, biotic and abiotic factors that may influence population-level gene flows of an Afzelia species (A. bipindensis). A morpho-genetic analysis of Afzelia species was carried out and confirmed the strong botanical resemblance between the taxa. The savannah species are diploid and have half the size of the genome of forest species that are tetraploid. The phylogenies of genes (nuclear and chloroplastic) differ from one another and do not allow the separation of tetraploid taxa from one another. Such differences can be generated as a result of episodes of ancestral hybridization between species. These hybridizations would probably be old and would have occurred between lineages of the forest species and A quanzensis (a species of the Zambezian savannahs) lineages. Polyploidy would have occurred between 7 and 9.4 million years in the evolutionary history of the genus. In addition, Bayesian assignment and reproductive isolation analyzes suggested interspecific crosses, but only in forest species distributed sympatrically. At a more limited spatial scale, we observed two well differentiated genetic groups in sympatry in A. bipindensis. These show a morphological differentiation and a phenological shift of flowering which can contribute to their reproductive isolation. This study highlighted some important points: the discovery of a polyploid complex within the Afzelia genus, the confirmation of the delimitation of the diploid savannah species and the need to revise the delimitation of forest tetraploid species. [less ▲]

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See detailCharacterizing Thiamine Status and Mechanisms of Thiamine Supplementation on Subacute Ruminal Acidosis Attenuation in Dairy Cows
Pan, Xiaohua ULiege

Doctoral thesis (2017)

Dairy cows are often fed high grain diets to maximize milk production in today’s intensive management farms. However, overfeeding high grain diets increases the risk of subacute ruminal acidosis (SARA ... [more ▼]

Dairy cows are often fed high grain diets to maximize milk production in today’s intensive management farms. However, overfeeding high grain diets increases the risk of subacute ruminal acidosis (SARA), which is characterized by prolonged decrease in rumen pH and high levels of lipopolysaccharide (LPS). SARA challenge has been confirmed to severely impair animal health, production performance and farm profitability, and more and more attentions have been paid to prevent the occurrence of SARA in dairy industry worldwide. Our teams’ previous research found that thiamine supplementation relieved SARA in dairy cows, but the modes of action of thiamine in SARA attenuation are still unclear. In this context, this thesis was conducted to increase our understanding of relationships between SARA induction and thiamine, and to explore the mechanisms of thiamine supplementation on SARA attenuation by determining its effects on rumen fermentation, microbiome composition and anti-inflammatory response. Firstly, the first experiment in Chapter III demonstrated that thiamine status in rumen and blood were altered by SARA induction and thiamine deficiency occurred during SARA challenge. Regression analysis proved the ruminal thiamine content was positively related to pH and the concentrations of acetate in the rumen, and negatively correlated to the lactate contents, indicating the altered rumen fermentation would affect thiamine status. Secondly, the mRNA expression of thiamine transporters in ruminal epithelium (Chapter IV) and ruminal bacteria compositions (Chapter V) in SARA and control cows were detected. We found that thiamine concentration was positively correlated with Bacteroides, Ruminococcus 1, Ruminobacter, Pyramidobacter and Fibrobacter, and the decrease in these genera implied SARA challenge altered ruminal thiamine status by inhibiting the growth of thiamine synthesis related bacteria. The positive correlation between ruminal and blood thiamine, and the down-regulation of thiamine transporters’ expression in rumen epithelium indicated the reduced ruminal thiamine synthesis and thiamine absorption by SARA challenge resulted in low blood thiamine content of SARA cows. Thirdly, the effects of thiamine on rumen fermentation (Chapter III), anti-inflammatory response (Chapter IV) and microbiome composition (Chapter V) were evaluated to reveal its mechanisms on SARA attenuation. We found that thiamine supplementation promoted acetate-producing bacteria including Ruminococcus 1, Pyramidobacter, Succinivibrio and Bacteroides, and decreased bacteria positively related to ruminal lactate (Succiniclasticum and Ruminococcaceae NK4A214). Consequently, rumen fermentation was improved by reducing the accumulation of lactate and increasing ruminal pH. In addition, thiamine supplementation alleviated inflammatory response in rumen epithelium by reducing the release of LPS and phosphorylation of NFκB protein, which is conducive to SARA attenuation. In summary, this thesis had increased our understanding of thiamine nutrition in dairy cows, and provided a new control strategy for subacute ruminal acidosis in dairy cows. However, further investigations are needed to deeply understand the relationship between thiamine and SARA induction, such as the isolation and validation of thiamine synthesis bacteria affected by SARA challenge, as well as to figure out metabolic pathways through which SARA induction affects thiamine synthesis in the rumen. Moreover, the impacts of overfeeding high grain diets on intestinal thiamine absorption are still unclear and need to be illuminated in dairy cows. [less ▲]

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See detailOmics insights into rumen ureolytic bacterial community and urea metabolism in dairy cows
Jin, Di ULiege

Doctoral thesis (2017)

Urea has been used in the diets of ruminants as a non-protein nitrogen source. Ureolytic bacteria are key organisms in the rumen producing urease enzymes to catalyze the breakdown of urea to ammonia (NH3 ... [more ▼]

Urea has been used in the diets of ruminants as a non-protein nitrogen source. Ureolytic bacteria are key organisms in the rumen producing urease enzymes to catalyze the breakdown of urea to ammonia (NH3), and the NH3 is used as nitrogen for microbial protein synthesis. In the rumen, hydrolysis of urea to NH3 occurs at a greater rate than NH3 can be utilized by rumen bacteria, and excess ammonia absorbed into blood may be harmful to the animals. Nowadays, little is known about the information of ureolytic microorganisms in the rumen, and the changes that occur in the rumen microbial and host metabolites induced by urea nitrogen have not been fully characterized. ‘Omics’ approaches, such as metagenomics and metabolomics have been applied to analyzing rumen microbial community and nutrients metabolism in dairy cows. The objective of this study is to investigate the rumen predominant ureolytic bacteria community and the mechanisms of urea utilization in ruminants using sequencing and metabolomics approaches. Firstly, an in vitro experiment trying to explore the ruminal ureolytic bacterial community was performed. Urea or acetohydroxamic acid were supplemented into the rumen simulation systems as the stimulator and inhibitor for ureolytic bacteria, respectively. The bacterial 16S rRNA genes were analyzed by Miseq sequencing and used to reveal the ureolytic bacteria by comparing different treatments. We found that urea supplementation significantly increased the proportion of ureC genes. The rumen ureolytic bacteria were abundant in the genera of Pseudomonas, Haemophilus, Neisseria, Streptococcus, Actinomyces, Bacillus and unclassified Succinivibrionaceae. Secondly, an in vivo experiment was taken to investigate differences in ureolytic bacterial composition between the rumen digesta and rumen wall based on ureC gene classification. Six dairy cows with rumen fistula were assigned to a two-period cross-over trial. One group was fed a total mixed ration without urea and the treatment group was fed rations plus 180 g urea per cow per day. Rumen bacterial samples from rumen content and rumen wall fractions were collected for ureC gene amplification and sequencing using Miseq. More than 55% of the ureC sequences did not affiliate with any known taxonomically assigned urease genes. The wall-adherent bacteria had a distinct ureolytic bacterial profile compared to the bacteria in the rumen content. The most abundant ureC genes were affiliated with Methylococcaceae, Clostridiaceae, Paenibacillaceae, Helicobacteraceae and Methylophilaceae families. Relative abundance of the operational taxonomic units (OTUs) affiliated with Methylophilus and Marinobacter genera were significantly higher in the bacteria on the rumen wall than that in the rumen content. Thirdly, based on the in vivo experiment, rumen fluid and blood samples were collected and analyzed using nuclear magnetic resonance spectroscopy and multivariate analysis of variance. Concentrations of valine, aspartate, glutamate, and uracil in the rumen, and urea and pyroglutamate in the plasma were increased after urea supplementation. Metabolic pathways include pantothenate and CoA biosynthesis, beta-alanine metabolism, valine, leucine, and isoleucine metabolism in the rumen, and urea and glutathione metabolism in the plasma were significantly increased by urea nitrogen. In conclusion, this study identified significant populations of ureolytic bacterial community that have not been recognized or studied previously in the rumen and provides a basis for obtaining regulatory targets to moderate urea hydrolysis in the rumen. The findings also provided novel information to aid understanding of the metabolic pathways affected by urea nitrogen in dairy cows, and could potentially help to guide efforts directed at improving the efficiency of urea utilization in the rumen. [less ▲]

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See detailEnhanced screening methods for pesticides in food based on travelling-wave ion-mobility-high-resolution mass spectrometry
Goscinny, Séverine ULiege

Doctoral thesis (2017)

The work presented in this thesis finds its origin in the need to develop ad hoc and novel analytical strategies to screen efficiently targeted pesticide residues in the sector of food control. Our work ... [more ▼]

The work presented in this thesis finds its origin in the need to develop ad hoc and novel analytical strategies to screen efficiently targeted pesticide residues in the sector of food control. Our work intended not only to monitor an increased number of pesticides but also to elaborate a new frame based on Ion Mobility-Mass Spectrometry (IMS-MS) for a confident and reliable use of screening pesticide data. The main part of this thesis was devoted to an investigation of using ion mobility, hyphenated to ultra-high performance liquid chromatography and Mass Spectrometry (UHPLC-IMS-MS), as a new dimension of separation for small polar organic molecules in complex biological samples without involving exhaustive sample preparation. The first objective of this study was dedicated to the development and optimization of UHPLC-IMS-MS using traveling wave ion mobility spectrometry (TWIMS). We have identified nitrogen as suitable gas for the mobility separation of multi-class pesticides and optimized the different T-wave parameters for a wide range of molecular weight pesticides. We observed for 100 pesticides tested that drift times gave a higher level of selectivity to the overall method as no interfering compound resulted at same retention time, drift time and measured mass from matrix blank samples. In addition, once the pesticide has been identified using its retention time, exact mass and drift time, the resulting cleaned mass spectrum facilitates the chemical structure elucidation. Key findings from this research show that drift times measurements are reproducible and independent from matrices tested and compound concentration leading to the proposition of using this parameter as a new identification point (IP). We have demonstrated that drift times can be used as an additional IP to increase confidence in the results without extending the analysis time or changing the sample preparation procedure. Based on reproducible data, we were the first group to report and recommend a 2% variation of drift times as quality criteria for identification purposes. In a few recent published papers, we noticed that research groups developing similar analytical strategies have extensively adopted the 2% proposed criterion. Obviously drift times are dependent of instrumental conditions. Hence, to apply the proposed approach with automated and wide scale screening methods further developments in processing software have been made which also allowed to convert drift times in calculated Collisional Cross Section (CCS) values by means of TWIMS calibration. The second aim of this thesis was dedicated to a comprehensive study of the reliability of CCS values derived from drift times for pesticides screening over a long period of time (3 years) with different ion mobility parameters. The results proved that CCS values are very consistent, as the measured values do not differ more than 1% from the in-house reference data library. Different calibration mixtures were also tested and results show that the type of the compound used for calibration does not influence CCS measurement. However, the results emphasized the importance of the first low m/z mobility calibration point (i.e. below 200 m/z) to guarantee full independence from instrument parameters and calibrant. The robustness of the CCS calibration was then tested by changing deliberately the IMS parameters and compare the measured CCSs with the reference CCSs. Three set of experiments were done by changing the IM velocity (static mode = fixed value and dynamic mode = velocity ramping) and also IM gas pressure. The first set of parameters gave CCS values within 2% error from the reference CCS throughout the pesticides mass range, while for the last 2 sets of parameters, deviations beyond 2% error away from the reference CCSs are clearly marked under the m/z 232 (first CCS calibration point). From these results, we clearly see that CCS values generated with the same calibration protocol are reproducible even for target masses under the first CCS calibration point, whereas robustness is guaranteed within the strict limits of the calibration range. To extend the calibration range to a larger window of molecular weights (in the lower and upper range) a combination of acetaminophene-polyalanine and a mixture of small molecules containing also polyalanine were tested. No significant deviations were observed between the two new calibration mixtures as all the pesticide results were within the 2% error. This observation demonstrates that the nature of the reference compounds used for calibration does not influence the outcome of the estimated CCS values for low molecular weight pesticides. Finally, an intercomparison study was designed to evaluate the relative capabilities of producing CCS values with a simple protocol for screening purposes. Four laboratories in three different countries (UK, USA and Belgium) were involved in the test. For this comparison, only monoisotopic ions were selected and 6 out of 40 pesticides selected had their masses under the first CCS calibration point (m/z 232). When comparing the percentage errors of each laboratory values to the calculated consensus value (mean of the CCS from the 4 instruments), two laboratories presented a few values outside the 2% error limits. Interestingly, when each laboratory used their in house reference CCS to calculate the percentage errors for a spiked mandarin extract, the results are well within the 2% CCS error window. These observations highlighted that the direct use of CCS values reported from the literature has to be treated with great care when applying the proposed approach. After this extensive study on CCS values, the third goal was to assess the possible added value of using CCS criterion when performing a UHPLC-IM-(HR)MS screening method of targeted pesticides. The approach has been tested in the framework of a proficiency test (EURL-PT-FV-16). The PT material was a sweet pepper homogenate containing 13 pesticides measured by LC in positive mode. Two additional pesticides can be added to this list, primicarb-desmethyl and tebuconazole, because they were in the sample but were not evaluated in the PT results by the organizers since their concentrations were below the minimum required reported limit of 0.01 mg kg-1. In total, we were expecting 15 detections by using our screening method. The approach proposed here is unconventional for screening and consists on one hand (scenario A), on large mass accuracy (20 ppm), large retention time window (0.5 min) and large CCS error (10%) in order to capture, in a first step, a maximum of detected compounds. 26 tentative candidates were then identified. In this scenario, when closing down first the mass accuracy window from 20 ppm to 5 ppm, 8 candidates were discarded. However, a wrong decision has been taken for two of them, (2 false negatives), requiring to trigger additional investigations. In the second step of scenario A, by selecting the 2% error for CCS, five additional residues did not meet the criterion and were ruling out, giving in total 13 detected compounds, actually present in the PT sample and 2 questionable data. In scenario B, when we directly apply a narrower CCS error percentage (from 10 to 2%) without filtering on mass accuracy we gain directly all the 15 compounds present in the PT sample without any false negatives and discard the 11 false positives in one step. These findings are indeed promising and require obviously confirmation at large scale within the pesticide laboratory end-users network equipped with IMS-MS and willing to apply the proposed screening strategy. Interlaboratory studies and PTs within the pesticide community are required to consolidate our findings during this thesis work. Regarding the treatment of data and software, considerable improvements have been made in terms of automatic extraction of mobility data and having a fully automated approach incorporating CCS values as a screening parameter has never been tested before this thesis. Nonetheless, there is room for improvements in terms of downsizing the acquisition file size which should enable faster processing and reporting time along with easier data storage. While the results from this thesis demonstrated that nitrogen was the most suited gas, Howdle et al. (1) have reported that the use of binary gas mixtures results in excellent selectivity enhancements over single gas composition for IMS separations and most importantly they demonstrated that this selectivity can be tuned by altering the binary gas composition. One can only barely imagine the impact of such results for IMS applications. Being able to choose the best gas mixture and/or develop gradient with variable gas composition during the mobility separation would most probably achieve better mobility resolution customized for specific applications or to create new opportunities for multi-class screening (e.g. pesticides, mycotoxins, food contact materials, food additives…). This new approach will trigger new research in the field of instrumental development to ensure control over the composition of gas delivered in the IMS cell and also how to adapt or create TWIMS calibration for these significant changes. The application space for ion mobility is vast, not only as a means of the specific pioneering application we developed here but in the richness of these measurements can provide in structural information of ions in many research fields including fundamental research. Conceptualization, design and construction of contemporary instruments were growing fast over the past few years. Emerging IM strategies developed by manufacturers based on proof-of-concept published papers encompass Overtone Mobility Spectrometry (OMS); confinement and mobility selective release like Trapped Ion Mobility Spectrometry (TIMS), or Cyclic Drift Tube Ion Mobility Spectrometry (Cyclic DTIMS) and more recently Cyclic Traveling Wave Ion Mobility Spectrometry (Cyclic TWIMS). For example, in Cyclic TWIMS, one remarkable feature is the use of one meter single path transit ring which was placed orthogonally to the primary beam travelling wave path of the instrument. This novel multi-pass cyclic device gives access to higher resolving power. As the Resolution (CCS/CCS) in T-wave increases in proportion to the square root of the device length, the one meter single pass in the ring being 4 times the length of a standard Synapt G2-S, the Resolution is doubled by cycle. Giles et al. reported up to 6 passes showing an acceptable ion transmission with a signal drop of only 15% (2). These emerging high-resolution IMS instruments clearly open new possibilities of separation of structural isomers low molecular weight compounds. Based on this research project, we are convinced that ion mobility used as an additional dimension of separation in hyphenated techniques can play a role in addressing the needs to provide reliable screening data and helping to reduce the rate of false negative and positive results prior to confirmation by quantitative methods. IMS-MS has become a key technology to answer chemical food safety issues as demonstrated by the rapidly expanding literature using IMS-MS over recent years. In a broader view, the concept of CCS data used as an additional identification tool and the development of new CCS databases will contribute to strengthen the needs in gathering reliable information to help the analyst in making right decision in the field of the very challenging qualitative screening analysis of trace chemical residues in food. [less ▲]

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See detailSoil Acidification in Southern China: Spatio-temporal Evolution and Effects on Phosphorus Availability
Zhou, Xiaoyang ULiege

Doctoral thesis (2017)

Rapid industrial development and intensive agriculture induced serious soil degradation in recent decades worldwide and specifically in China. In cropland, soil acidification and nutrient deficiency are ... [more ▼]

Rapid industrial development and intensive agriculture induced serious soil degradation in recent decades worldwide and specifically in China. In cropland, soil acidification and nutrient deficiency are often associated with increased use of nitrogen (N) fertilizers. Soil acidification can lead to reduction of phosphorus (P) availability, even though with high inputs of P fertilizer. The studies presented in the thesis deal with spatio-temporal evolution of soil pH in different soil types and land uses in southern China and effects of soil acidification on soil P availability. Evolution of inorganic P fractions in Red Soil was characterized upon fertilization trials, as a response to long-term fertilization and soil acidity changes. The first focus of the thesis deals with spatio-temporal evolution and main factors of soil acidification in different soil types, parent materials and land uses of Southern China. Firstly, data from 20 monitoring sites under 25-year fertilization on Paddy Soil were investigated to research changes of pH. Paddy Soil pH significantly declined from 1988-1998, then stabilized from 1998-2013 with conventional fertilization. Chemical N fertilization, manure application, soil available N and total N increases were significantly correlated with soil pH. Secondly, changes of pH in Red Soil and Paddy Soil were assessed in 32 monitoring sites of Hunan Province (Southern China) under 10-year fertilization in order to analyze soil acidification in different soil types and agro-systems. Soil pH decline was observed in Paddy Soils under rice-vegetable rotation but not observed in Paddy Soil under continuous cropping with rice. Soil pH significantly declined in Red Soil with high initial soil pH. Thirdly, spatio-temporal characteristics of soil pH were investigated by comparison of soil pH between 1982 and 2014 in Qiyang County (Hunan Province). Average topsoil pH declined of 0.58 units between the two surveys. Soil pH in the south was lower than in the north both in 1982 and 2014. Land use and parent materials are the main drivers of differences in the soil pH changes in Qiyang County. Soil pH declined significantly in forest and upland crop over non-alkaline parent materials during 1982-2014 period. Chemical N fertilizer application can have generated 12-42 kmol H+ ha-1yr-1, which is much higher than removal by crop harvest. Reduction of chemical N fertilization and return of straws to field should be conducted to reduce H+ production and supplement base cations in Qiyang County. The second approach studied evolution of inorganic P fractions in Red Soil under 25-year fertilization, and available P and inorganic P fractions responses to various soil acidity levels. Inorganic P fractions increased under P fertilization from 1990-2015, especially Ca2-P, Ca8-P and Al-P, but inorganic P fractions significantly decreased without P fertilization. Contributions of soil properties (SOC, C:P ratio and N:P ratio) and cumulative P apparent balance (CPAB) to inorganic P fractions were ≥ 95%, while interaction of CPAB and soil properties made greater contributions than did any single factor. Soil dissolved inorganic P (DIP) decreased with rising pH value, and a minimum DIP was observed between pH 5.5 and 6.5. Olsen-P, Ca-P and Al-P increased significantly with pH between 3.4 and 5.0. Soil with pH <5.0 P availability was much lower than soil with pH ≥5.0. Managing soil acidity is a key issue regarding availability of P in Red Soil of China and our results suggest that at least a pH of 5.0 should be targeted. [less ▲]

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See detailCaractérisation des argiles utilisées dans le secteur de la terre cuite de la région de Marrakech en vue d'améliorer la qualité des produits
El Boudour El Idrissi, Hicham ULiege

Doctoral thesis (2017)

The purpose of this study is to characterize the clay raw materials being exploited and used in the earthenware sector (pottery and building materials) of Marrakech region. It aims to improve product ... [more ▼]

The purpose of this study is to characterize the clay raw materials being exploited and used in the earthenware sector (pottery and building materials) of Marrakech region. It aims to improve product quality in 12 sites within a radius of 10 to 80 km around the city of Marrakech, where are active more than 850 potters spread over about 550 workshops. This characterization also aims at establishing a database on the properties of the raw materials of Marrakech and on the characteristics of the products. This will help in the selection of the most suitable materials, which generate the least defects, in restoring the historical sites of the city and in linking archaeological ceramics with their possible source of clayey material. A total of 34 samples of clay raw materials were collected from the various studied sites. 26 ceramic pastes were formed from these raw materials. Ceramic pastes have been characterized for their particle size (semi-wet sieving and laser particles size), chemical (XRF) and mineralogical compositions (XRD), plasticities (Atterberg limits), carbonate content (Bernard's calcimetry), drying behaviour (Bigot curve) and loss on ignition. The fired products were characterized by firing shrinkage, water porosity, compressive and flexural strengths and by SEM combined with EDX. The studied ceramic pastes show a large particle size variation: clay (18-66%), silt (12-53%) and sand (5-65%). Mineralogically, they are composed mainly of clay minerals (25-60%), quartz (20-55%), feldspars (5-35%), carbonates (≤15%), diopside (5-10%) and hematite (1-3%). Clay minerals are formed by illite (10-40%), kaolinite (5-15%), interstratified (≤10%), talc and pyrophyllite (≤10%), vermiculite (5%) and chlorite (≤5%). The chemical composition shows that the majority of the pastes are composed of SiO2 (48-74%), Al2O3 (12-20%), Fe2O3 (3-8%), CaO (0.4-8%), K2O (2-5%), MgO (0.5-3.5%), Na2O (0.1-2%), TiO2 (0.8-1.2%), P2O5 (≤ 0.4%) and MnO (≤ 3%). Plasticity varies from one paste to another with plasticity indices between 15 and 32. The shrinkage on drying is between 4 and 10%. For a firing temperature of 1050°C, the firing shrinkage of the various pastes is between 0.5 and 5%. The mineral transformations during firing are very diversified from one sample to another and from one site to another. The comparison of the obtained results shows that granulometry, mineralogy and degree of diagenesis are the main factors controlling plasticity. We showed a relationship between the properties of the pastes (particle size, mineralogy and plasticity) and the type of product. We proposed solutions for each of the many observed defects (poor quality of raw material, lime blowing, lime efflorescence, inadequate drying procedure, cracking, blisters, black hearts, crazing and poor ovens quality). In addition, this study valuated the clay raw materials of the Marrakech region for the use in the field of production of building materials. [less ▲]

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