References of "Dissertations and theses"
     in
Bookmark and Share    
Full Text
See detailOn the Model Validation in Nonlinear structural Dynamics,
Kerschen, Gaëtan ULg

Doctoral thesis (2002)

Detailed reference viewed: 54 (12 ULg)
Full Text
See detailContamination and detoxication processes in marine mammals from European coasts
Das, Krishna ULg

Doctoral thesis (2002)

The aim of the present work was to determine the relationships between trace metal levels and different factors such as species, geographic origin, diet, age and general body condition of marine mammals ... [more ▼]

The aim of the present work was to determine the relationships between trace metal levels and different factors such as species, geographic origin, diet, age and general body condition of marine mammals from European seas [less ▲]

Detailed reference viewed: 51 (19 ULg)
See detailRésolution d'un problème aux limites à frontières libres au moyen d'un algorithme de remaillage adaptatif et anisotrope
Béchet, Eric ULg

Doctoral thesis (2002)

This thesis focuses on the study and development of remeshing algorithms for the simulation of free surface flows in porous medium. This kind of flow is coming up with the mould filling phase when ... [more ▼]

This thesis focuses on the study and development of remeshing algorithms for the simulation of free surface flows in porous medium. This kind of flow is coming up with the mould filling phase when manufacturing composite parts with the RTM process (Resin Transfer Moulding), for which the majority of the applications of this research have been done. Remeshing methods presented here are based on the Delaunay criterion for triangulations. An adaptation for curved surfaces is proposed here. This adaptation avoid to keep the link with an exact representation of the CAD surface, and allows the use of a simple tessellation, instead. In fact, the ability to generate anisotropic surface meshes without keeping the link with the tool used to model those surfaces allows to interface finite element solvers with ease. A first publication has been made, based on this part. For practical problems arising in RTM, the ideas coming from the first part have been adapted to the goal of generating anisotropic elements. Thus, the Delaunay criterion considered here is anisoptropic. In fact, the remeshing method presented in this thesis allows a better simulation of the advancing flow front by using anisotropic elements flattened in the direction of the flow. Thus, the resolution of the flow front is high an shows a smooth and regular front. This was not the case with simulations made on a fixed and isotropic mesh, with the same number of degree of freedom. For the evolution of the free surface in time, a level-set approach was originally combined with the remeshing algorithm in order to control the time step independently to the mesh. A second publication has been based on this part. An adaptation of the remeshing algorithm is proposed for thermal problems in the third part of this thesis. In fact, the remeshing allows a better control of the numerical (artificial) diffusion that arise while solving a transport phenomenon. This diffusion is related to the spatial discretisation step. In the case of RTM it happens frequently, in the vicinity of the flow front and when temperature differ notably to the temperature of the mould and the fibres, that the numerical diffusion is an obstacle preventing to achieve a precise simulation of the thermal behaviour in the mould. Transport equations require also a condition on the time step to stabilize the numerical scheme when solved on an Eulerian grid. A variable time-stepping for the sole calculation of transport phenomenon is proposed. A study aimed to prove the possibility of generating a fixed mesh for the whole simulation is proposed for planar geometries. An error estimator based on the Hessian matrix in pressure is used to generate a mesh that will make the interpolation error uniform in the domain. At the same time, an heuristic is built to stretch elements in function of the successive positions of the mesh, determined a priori. This is improving the approximation of the front that is made during the simulation. Finally, an analytical study of a injection case is done, showing the difficulty to generate a mesh satisfying two conditions : uniformity of the interpolation error, and uniformity of the Courant number (which is shown to minimize the numerical diffusion in transport equations). This work was published in a third article. The last part of this thesis focuses on the application of the error estimator to curved surfaces. The surfaces considered here are discrete, it is necessary to separate the interpolation error from the geometrical error. This is done to avoid useless refinement of the mesh near angles in the geometry. An sample case from industry is studied. This part composes the fourth article. Finally, a discussion on the whole research made in this thesis is presented. [less ▲]

Detailed reference viewed: 2 (1 ULg)
Full Text
See detailLes conflits de procédure - étude de droit international privé comparé
Wautelet, Patrick ULg

Doctoral thesis (2002)

The dissertation focuses on multiple (or parallel) proceedings in private international litigation. In international civil disputes it is not unusual that jurisdiction for a particular dispute exists in ... [more ▼]

The dissertation focuses on multiple (or parallel) proceedings in private international litigation. In international civil disputes it is not unusual that jurisdiction for a particular dispute exists in several countries. In that case, each party may be tempted to start litigation in the forum most favorable to it, for example to take advantage of the forum’s more generous recovery rules or the extended possibilities of discovery. Similarly, one party can also choose to initiate proceedings in different countries for the same dispute. The question arises how the legal systems involved will and should deal with such ‘multi-fora’ disputes. The first question addressed is whether and to what extent the international legal community should strive to prevent and/or eliminate such duplicate proceedings. It is undubitable that multiple proceedings could lead to undesirable consequences, such as conflicting judgments. Concurrent jurisdiction also brings about a waste of (scarce) judicial resources, and unnecessary expenses for the litigants. To prevent altogether parallel proceedings from happening however, seems at best utopic or even dangerous. Even if the international community were to achieve a global agreement on a comprehensive set of jurisdiction rules, one cannot imagine that there rules would designate one and only one court for each particular dispute. The desire to concentrate jurisdiction for all related disputes in the hands of one court is indeed but one of the numerous factors influencing the allocation of jurisdiction in international matters. The dissertation therefore undertakes to study the rules and instruments that can be used to resolve parallel litigation once multiple proceedings have been issued. The study learns that courts can adopt a variety of attitudes when faced with parallel litigation. A legal system can decide to ignore altogether the fact that a foreign court is seised of parallel proceedings, relying on the res judicata effect of the first decision to be rendered. It can also decide to abstain from taking up the case in deference to the foreign proceedings. Finally it can try to put an end to the parallel proceedings, by enjoining a party from further proceeding before the foreign court. After an in-depth analysis of these different policies and of the various rules and instruments in which they are embodied, my conclusion is that the preference should be given to mechanisms whereby one court voluntarily declines jurisdiction in favor of the other. The preference I express for a mechanism of ‘international abstention’ is however qualified. Whether or not a court declines jurisdiction in favor of a foreign court, will depend inter alia on the confidence it has that justice will be done in the foreign forum. Even with a minimum level of trust and confidence between jurisdictions, the abstention rule can follow different models, from the continental lis alibi pendens rule, which offers almost automatic priority to the court first seised, to the common law doctrine of ‘forum non conveniens’, where priority goes to the more appropriate forum. Between these two extremes lies a world of nuances. The dissertation therefore attempts to formulate an abstention rule which will reconcile these seemingly opposed visions and explain in which circumstances and under which conditions a court should or can decline jurisdiction in deference to litigation pending before a foreign court. [less ▲]

Detailed reference viewed: 479 (11 ULg)
Full Text
See detailNaissance et développement du culte de la Trinité. Etude des manifestations de la dévotion en Lotharingie du IXe au XIIe siècle.
Close, Florence ULg

Master of advanced studies dissertation (2002)

Ce mémoire de DEA consistait en la présentation d'un projet de thèse détaillé accompagné d'une bibliographie exhaustive et en un développement de l'un des points évoqués dans ce projet sous la forme d'une ... [more ▼]

Ce mémoire de DEA consistait en la présentation d'un projet de thèse détaillé accompagné d'une bibliographie exhaustive et en un développement de l'un des points évoqués dans ce projet sous la forme d'une contribution scientifique conséquente (ca. 120 p.), en l'occurence la recherche de l'archétype de l'office de la Trinité attribué à l'évêque de Liège, Etienne (901-920). [less ▲]

Detailed reference viewed: 64 (7 ULg)
See detailLa rationalisation dans l'industrie belge de l'Entre-deux-guerres
Geerkens Provin, Eric ULg

Doctoral thesis (2002)

L'industrie belge a-t-elle fait, dans la première moitié du XXème siècle, l'expérience de ce qui, dans des pays voisins, a été étudié sous le nom de rationalisation, ou en a-t-elle été empêchée par la ... [more ▼]

L'industrie belge a-t-elle fait, dans la première moitié du XXème siècle, l'expérience de ce qui, dans des pays voisins, a été étudié sous le nom de rationalisation, ou en a-t-elle été empêchée par la prépondérance en son sein d'activités anciennes, nées de la Révolution industrielle? Pour répondre à cette question, ce livre fait le choix de donner un très large aperçu de mesures d'organisation, saisies autant que possible à l'échelle de l'atelier; il prend appui sur le dépouillement de nombreux fonds d'archives d'entreprises et d'une abondante littérature technique, patronale et syndicale. Il s'attache d'abord aux pratiques d'organisation présentées en référence non exclusive à la taylorisation, à la recherche de la fluidité du processus de production et aux techniques de contrôle centralisé des exploitations; il réserve ensuite une large attention à la gestion du facteur humain, depuis la formation et la sélection professionnelles jusqu'à la politique sociale patronale, en passant par la question du commandement. Enfin, il tente de mesurer l'impact du changement organisationnel sur les conditions d'activité des travailleurs, de saisir leurs réactions et celles du mouvement ouvrier organisé. S'en dégage un bilan nuancé de la rationalisation dans l'industrie belge à la veille de la Seconde Guerre mondiale, prenant en compte le poids de la conjoncture, les contraintes structurelles, internes et externes aux entreprises, et le jeu — conflictuel ou coopératif — des acteurs. [less ▲]

Detailed reference viewed: 29 (6 ULg)
Full Text
See detailApport de la réaction de polymérisation en chaine dans le diagnostic de l'aspergillose invasive
Hayette, Marie-Pierre ULg

Doctoral thesis (2002)

Les aspergilloses invasives surviennent chez les patients immunodéprimés pour la plupart neutropéniques. leur diagnostic est souvent trop tardif et la mise sous traitement aboutit à l'échec dans plus de ... [more ▼]

Les aspergilloses invasives surviennent chez les patients immunodéprimés pour la plupart neutropéniques. leur diagnostic est souvent trop tardif et la mise sous traitement aboutit à l'échec dans plus de 50% des cas. Aussi, il est nécessaire de développer de nouvelles techniques de diagnostic plus sensibles. Dans cette étude deux volets ont été développés: tout d'abord la mise au point d'une technique de polymérisation en chaîne pour la détection d'ADN d'Aspergillus sp. et son utilisation dans les lavages bronchoalvéolaires. Cette étude a montré que la technique développée était sensible et spécifique mais ne permettait pas de distinguer entre infection et colonisation. La seconde étude a consisté en la mise au point d'un modèle expérimental d'aspergillose invasive sur le lapin, dans le but d'évaluer la détection d'ADN fongique par PCR sur sang périphérique, parallèlement à la détection d'antigène galactomannane sérique par ELISA. Les résultats de cette étude ont montré qu'il était possible de détecter de l'ADN fongique dans le sang mais de façon inconstante et souvent postérieurement à la détection d'antigène galactomannane par ELISA. Cela permet de conclure que la place de la PCR Aspergillus sur sang périphérique reste encore à définir dans le diagnositic des aspergilloses invasives. Cependant elle peut être utilisée en complément d'autres techniques diagnostiques. [less ▲]

Detailed reference viewed: 95 (6 ULg)
Full Text
See detailSynthesis and potential of new functional aliphatic polyesters
Xudong, Lou

Doctoral thesis (2002)

Detailed reference viewed: 13 (5 ULg)
Full Text
See detailDéveloppement et mise au point d’une boucle d’étalonnage pour vanne de régulation en vue d’une future accréditation
Caprace, Jean-David ULg

Master's dissertation (2002)

This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the ... [more ▼]

This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the realisation of a test bench for hydraulic control valves in preparation for qualified calibration (ISO 17025). Enventually measurement of actual flow characteristics will allow to optimise the use of valves in piping systems. The work has been done in several phases: design, study of metrology, study of standards, implementation and finally preliminary tests and results. The dimensioning of the test bench led to the drawings and draughts of all pipe sections and of the rejection canal (valves with diameter from 100 to 300 mm). The prssure drop has also been evaluated over the whole system. Concerning methodology, measuring techniques were identified, sensors and their signal handling units have been chosen and dimensioned: weirs, pressure sensor, torque meter and electromagnetic flow meter. With the aim to prepare the future qualification of the test bench, existing standards were identified and studied. Their recommendations have been applied where possible. Finally the test bench has been constructed, which has been a rich experience because of the many unexpected problems related to technique as well as to methodology. Preliminary test results for the calibration of a butterfly valve are promising. Nevertheless there is still some work to do before calibration can be qualified. Anyhow the data already collected and the many observations done during these tests were a good opportunity to analyse technological problems and standardisation. So this as a whole results in a data package which can be the base for future projects. [less ▲]

Detailed reference viewed: 81 (9 ULg)
See detailMyoglobinurie atypique chez les chevaux au pré: une série de cas en Belgique
Delguste, Catherine ULg

Master of advanced studies dissertation (2002)

Atypical myoglobinuria in grazing horses was described in United Kingdom and Germany between 1984 and 1996. Fourteen horses were presented at the University of Liège between November 2000 and April 2001 ... [more ▼]

Atypical myoglobinuria in grazing horses was described in United Kingdom and Germany between 1984 and 1996. Fourteen horses were presented at the University of Liège between November 2000 and April 2001, with a clinical history suggesting atypical myoglobinuria. Lesions were similar to those previously described. All horses were at rest and grazing when they developed clinical signs. Three times, the syndrome killed several horses grazing together. Horses were generally found recumbent, nearly or totally unable to stand up. They were presenting tachycardia, polypnoea and myoglobinuria, and died rapidly. When performed, blood analysis revealed severe muscular enzymatic activity rises. Histopathology revealed pulmonary congestion and oedema, and squeletal muscular fibers degeneration, mostly in respiratory and postural muscles. These observations are in accordance with cases of atypical myoglobinuria previously described in UK and Germany. The aetiology of this pathology is still unknown, despite of research attempts. An epidemiological inquiry protocol was developed in order to investigate upcoming cases within the scope of aetiologic research. Atypical myoglobinuria in grazing horses was described in United Kingdom and Germany between 1984 and 1996. Fourteen horses were presented at the University of Liège between November 2000 and April 2001, with a clinical history suggesting atypical myoglobinuria. Lesions were similar to those previously described. All horses were at rest and grazing when they developed clinical signs. Three times, the syndrome killed several horses grazing together. Horses were generally found recumbent, nearly or totally unable to stand up. They were presenting tachycardia, polypnoea and myoglobinuria, and died rapidly. When performed, blood analysis revealed severe muscular enzymatic activity rises. Histopathology revealed pulmonary congestion and oedema, and squeletal muscular fibers degeneration, mostly in respiratory and postural muscles. These observations are in accordance with cases of atypical myoglobinuria previously described in UK and Germany. The aetiology of this pathology is still unknown, despite of research attempts. An epidemiological inquiry protocol was developed in order to investigate upcoming cases within the scope of aetiologic research. [less ▲]

Detailed reference viewed: 12 (2 ULg)
See detailEtude de l'effet d'un stimulus gravitationnel induit artificiellement sur la formation du bois de tension et du bois opposé dans de jeunes pousses de peuplier (Populus euramericana cv "Ghoy"
Jourez, Benoît ULg

Doctoral thesis (2002)

The tension wood of arborescent dicotyledons can be distinguished by its anatomical, chemical, physical and mechanical characteristics which give to it a specific behavior. In its development interfere ... [more ▼]

The tension wood of arborescent dicotyledons can be distinguished by its anatomical, chemical, physical and mechanical characteristics which give to it a specific behavior. In its development interfere complex mechanisms able to perceive endogenous and exogenous stimuli acting on the cambial zone during the new cell differentiation and maturation. Its particular distribution in the shoot induces a dissymetrical distribution of growth stresses capable to modify their orientation. The supporting thesis of this study maintains the idea of a quantitative responses of the young shoots of poplar which develop under controlled conditions, as a reaction to a gravitational stimulus artificially induced. To demonstrate this, the experimental approach consisted on one hand, to determine the reaction induced by the stimulus in the wood structure. On the other hand, to attempt to establish the existence of a modulation of the shoots reaction in regard of the duration and of the intensity of the stimulus application, while applying increasing levels of these parameters. The anatomical observations were based on microscopic cross sections taken from the base of the shoots. The analysis of these sections were realized using an image analyzing technology. The anatomical modifications induced by the stimulus concern all the elements of the wood structure. They generate repercussions on the physical properties of the wood of micro samples composed exclusively of gelatinous fibers. As the stimulus is applied during increasing duration it appears that the formation of the tissues in the opposite wood and in the tension wood requires a relatively short time of presentation. It shows also the rapidity of reaction of the shoots estimated by the latent period. Short duration events are capable to produce repercussions on the wood structure. The rate of cellular division, more important in the tension wood tissues, as measured on the upper face of a bent axis leads to a pith eccentricity in the shoot. The formation of tension wood, a modification of the secondary growth and the movement of the axis are the major modifications quantitatively linked to the intensity of the stimulus. Moreover, the evolution of the measured parameters demonstrates the existence of a natural equilibrium position of the shoots, different from the vertical position, and to which they attempt to return by an straightening or a sagging motion induced by the tension wood tissue. All these results indicated that tension wood should not be considered as a defect but rather as a efficient mechanism for the shoot allowing adaptation and harmonious development in its own environment. [less ▲]

Detailed reference viewed: 18 (4 ULg)
See detailStatistical analysis of general practitioner rural database focused on cardio-vascular patients
Magis, David ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 10 (3 ULg)
Full Text
See detailRésonances et dissipations
Jancart, Sylvie ULg

Doctoral thesis (2002)

The discovery of protosolar disks and exoplanets around several stars has revitalized the research combining mean motion resonances and dissipative forces in the elliptic spatial restricted three-body ... [more ▼]

The discovery of protosolar disks and exoplanets around several stars has revitalized the research combining mean motion resonances and dissipative forces in the elliptic spatial restricted three-body problem. This thesis presents that combination in three different ways. A semi-numerical model simulates the behaviour of test particles under the effects of well- known dissipative forces or generic forces. This model is valid for any orbital eccentricities or inclinations, even at high values, and captures around sym- metric and asymmetric equilibria are reproduced. The most common result is the capture in Kozai resonance. Analytical models have been developed to understand the influence of each particular term in the development of the hamiltonian function. An other faster numerical model allows the possibility of following the evolution of thousands of test particles. This mapping has been applied in the study of the stability of the F-ring of Saturn. [less ▲]

Detailed reference viewed: 10 (3 ULg)
Full Text
See detailQualité spectrales des tests standardisés universitaires - Mise au point d'indices édumétriques d'analyse de la qualité spectrale des évaluations des acquis des étudiants universitaires et application aux épreuves MOHICAN check up '99
Gilles, Jean-Luc ULg

Doctoral thesis (2002)

For several decades almost all European university institutions have been faced with a strong increase in their number of students whereas the allocated budgets have not increased in proportion (Gibbs ... [more ▼]

For several decades almost all European university institutions have been faced with a strong increase in their number of students whereas the allocated budgets have not increased in proportion (Gibbs & Jenkins, 1992). The universities of the French Community of Belgium do not escape this heavy tendency: compared with the 1972 situation, the number of students has increased to 150% and, in constant francs, subsidies have remained unchanged (Debry & al., 1998). This situation leads in the first cycles of studies, where the students are most numerous, to a massive use of standardized examinations with multiple choice questions (MCQ) which makes the assessment of great groups of students possible within reasonable time delays. The confidence degrees technique associated to the MCQ makes it possible to bypass the "binary" character of students assessment performance (the selected proposal is either correct, or incorrect) provided that a series of methodological rules are followed called "admissible probability measurement procedures" by Shufford & al. (1966). Among those rules: ask the students to express their confidence in a numerical (probabilistic) scale. The one adopted offers 6 degrees of subtlety: 0%, 20%, 40%, 60%, 80% and 100% of confidence. By inviting the student to accompany his choice by the percentage of chances to be correct he attributes to his answer, we allow more subtleties in the analysis of his performances. At one extreme, the choice of a wrong answer accompanied by the maximal percentage of certainty (100%) presents the worst situation, in which the student provides an erroneous answer by estimating that he has a maximal chances to be correct. On the other hand, the student who answers correctly with a maximal certainty shows an assured performance. Between these two extremes, other zones can be identified in the "spectral analysis" of the performances. Jans & Leclercq (1999) propose a specific terminology. They distinguish "ignorance" (correct answer and weak certainty), from "partial knowledge" (correct answer and average certainty), and "perfect knowledge" (correct answer and high certainty). Such spectral gradations were also considered by these authors in the case of an incorrect answer ("mistaken knowledge" and " fallacious knowledge" or "dangerous knowledge"). Usually, the confidence percentages which accompany the MCQ answers are used to deliver more subtler feedback on each student's spectral performances. The innovative aspect of our approach lies in the fact that we have exploited the confidence percentages provided by the students to provide spectral information on the quality of the questions (as opposed to information on the quality of students performances). Our research thus led to the development of a series of original indices for the analysis of assessments' spectral quality. These spectral indices are intended to be used when the assessor must highlight problematic MCQ and, within those, the proposals which contain anomalies. Our starting intuition for the construction of these new indices is as follows: logically the students who answer a question correctly should provide percentages of certainty higher than the students who answer incorrectly. Thus, for a multiple choice question which functions normally from the point of view of the certainty percentages use, we should observe among the students who choose the correct answer a tendency to answer with higher percentages of certainty and, in parallel, among the students who choose a wrong proposal a tendency to answer with lower percentages of certainty. We will then say that there is "spectral coherence". In the case where this situation does not arise, for example when students choose higher certainty percentages for one of the incorrect answers rather than for the correct answer, we are confronted with a problem of inconsistency in the use of the percentages of certainty, we will then speak of "spectral inconsistency". To measure spectral coherence we created two new types of indices starting from the classical point bi serial correlation coefficient (classical rpbis) calculation principle. Let us recall that in the case of the rpbis, the choices or the rejections (1 or 0) of each proposal of a MCQ are correlated with the numbers of correct answers obtained to the whole test. The classical rpbis makes it possible to evaluate up to what extent each proposed alternatives solutions of each MCQ discriminates the students according to the criterion of the number of correct answers. Logically, one expects that the students who collect a high number of correct answers tend to choose the correct answer for a given question and that the students which collect a lower number have a tendency to choose an incorrect proposal. The two new types of spectral coherence indices of measurement are: (1) the Spectral Contrasted rpbis (rpbis SC) and (2) the Spectral Contrasted rpbis calculated after Turbo analysis (rpbis SCT). During a former research we had already used information related to the confidence degrees to calculate a new type of rpbis, the Spectral rpbis or rpbis S (Gilles, 1998). The rpbis S was developed in order to analyze the tendency to use higher certainty in case of correct answers than in case of incorrect answers. Within the framework of this thesis we propose a first improvement of the rpbis S by implementing a "contrasted treatment" for the MCQ incorrect proposals. We use the name "rpbis SC" to indicate the rpbis S is constructed with a "Contrasted treatment" which consists in the computation of the rpbis SC of an incorrect answer by using the data of the students who choose this wrong response in contrast with the data restricted to the students who choose the correct answer excluding the data from the students who choose an other incorrect answer. The advantage lies in the elimination of the data of the students who have chosen the other incorrect answers. This avoids introducing into the measurement of spectral coherence, the "background noise" generated by the data of the other incorrect answers. The principle of "turbo analysis", consists in operating a selection in the data used for rpbis SC calculation on the basis of the level of realism reached by the students. We can thus increase the reliability of information related to the spectral indices by restricting the data to the students who make less errors in their self-assessments (in their use of certainty percentages). We measure the level of errors of self-assessments made by the students by using the index of realism which varies from 0 to 100 (Leclercq & al, 2000). The name rpbis SCT indicates rpbis SC calculated with a Turbo analysis. The word "turbo" refers to the rise to power of the instrument in terms of the quality of information provided as one restricts oneself progressively to data from sets of students who make less and less errors in their self-assessments. We mention in the index's name the threshold of realism used to select the data. For instance rpbis SCT80 was calculated starting from the data of the students whose realism is equal to or higher than 80 (those who make between 0% and 20% of errors in their self-assessments). The new indices rpbis SC and rpbis SCT, which are in the heart of this research, are designed for the detection of problems located at the "alternatives level" inside the MCQ. We also adapted other spectral indices initially planned for the analysis of students performances so that these indices deliver information on the MCQ performances, at a "question level". On one hand, the index of Realization of the predictions by question (Rq) or the quantity of errors of self-assessment contained in the results for a question and, on the other hand, the index of Centration per question (Cq) or the level of over or under confidence in the results for a question. Lastly, we also measured the level of spectral coherence of a question (NCSq) by taking into account the rpbis SC of the various proposals of a MCQ. The "turbo analysis" principle was also applied to the calculation of these spectral indices. We tried to test these new spectral indices designed for detection of suspect alternatives within suspect MCQ using the data of several thousands of answers and certainty percentages collected during the ten standardized tests of the MOHICAN project (Leclercq & al., 2001). They consisted in ten tests of knowledge of the principal subjects at the level of the end of secondary education which were submitted to groups of students entering first year studies in eight of the nine university institutions of the French Community of Belgium (the number of questioned students varied between 1.392 and 3.846 according to tests). These standardized tests consisted of MCQ for which students were invited to choose one answer and systematically accompany it with a percentage of certainty. The students had, not only to state which was their correct proposal, but also which was the percentage of chances to be correct that they granted to each one of their answers. No academic scores were delivered for these (Check up) MOHICAN tests (each student received a diagnostic feedback and the assessors a global feedback). Anonymity was guaranteed. The choice of the percentages of certainty was thus influenced neither by a scale of tariff of points nor by granting a final score which could have affected the later academic course of the student. The total number of MCQ for the ten MOHICAN tests was 173. For two MCQ among them, the 3rd and the 20th question of the general knowledge test in History and Socio-Economy, the values obtained with the spectral rpbis indicate situations of marked spectral inconsistency, the students tending to give lower percentages of certainty for the answers considered as correct and higher percentages of certainty for the incorrect answers. Studying the proposals of the two problematic MCQ by using the classical rpbis indices, we notice that the two MCQ do not function correctly from the point of view of classical discrimination. When we ask for the opinion of the experts of the contents, they confirm that the two MCQ display problematic results: for one of the questions a wrong proposal could also be regarded as being a correct answer and for the other, there is an error in the encoding of the correct answer. For these two questions there is thus convergence of three different perspectives: (1) that of the classical rpbis, (2) that of the experts and, (3) that of the spectral coherence measured using the spectral rpbis. In the case of the MOHICAN tests, the spectral analysis thus allows to highlight two questions that a more qualitative analysis (posterior opinions of the experts) as well as a classical analysis of discrimination (classical rpbis) also indicate as questions with problems. Does the spectral analysis make it possible to perform better than the classical analysis of discrimination (classical rpbis) for locating the problematic questions and the proposals which contain anomalies? This issue has been tested. We analyzed the 173 MCQ of the 10 MOHICAN tests by using the spectral rpbis (rpbis SC, rpbis SCT80 and rpbis SCT90) as well as the classical rpbis indices. We also reviewed the comments formulated by the experts of the contents in connection with each question. From these analyses it comes out that in addition to the two MCQ already discovered previously, 14 other questions are highlighted. The classical rpbis indicates anomalies in each one of these 14 MCQ. Six MCQ present abnormal values at rpbis SC. Only one MCQ obtains an abnormal rpbis SCT80. No MCQ obtains an abnormal rpbis SCT90. Among these 14 questions, only 3 are pointed as problematic by the experts. With regard to the three questions singled out by the experts, they lead to a set of proposals that only the rpbis SC designates, whereas for the rpbis SCT80 and the rpbis SCT90, they are not highlighted. As far as the classical rpbis is concerned one only of the two problematic proposals for only one of the three questions appears. Therefore, from the point of view of "detection", rpbis SC were more effective to highlight the problems raised by the experts than were the other indices. This analysis shows that the various types of rpbis induce also "false alarms", abnormal values collected by proposals whereas the experts of the contents do not detect particular problems. From this point of view, the rpbis SC, with 7 false alarms, is less effective than the rpbis SCT80 which causes only one of them and less than the rpbis SCT90 which starts none, but rpbis SCT80 and rpbis SCT90 fail by "undetecting" the three questions pointed by the experts. On the other hand the rpbis SC starts less false alarms than the classical rpbis which has 10 false alarms. These qualities of lower "undetection" and less "false alarms" are crucial when the question arises of highlighting a problematic MCQ. When we correct the anomalies contained in certain answers within the MCQ, we can, from now on, not only evaluate the spectral impact of these corrections on the answers ("alternatives level"), but also on the whole question by comparing the values obtained with the indices of NCSq, Rq and Cq before and after changes are operated (at the "question level"). We did this for the two most problematic questions of the general knowledge test in History and Socio Economy and quantified the gains in spectral coherence. The improvement of the spectral coherence of the test was also measured by calculating the average values of the spectral indices at the "question level". These average indices thus made it possible to evaluate the spectral impact on a third "test level" of the assessment. In parallel, we also observed an improvement of the fidelity of the test using the classical Cronbach's alpha coefficient. Using the spectral indices developed within the framework of our thesis and usable with three levels of spectral analysis: "ALTERNATIVES", "MCQ" and "TEST", we open a new way for the analysis of the quality of standardized tests and their regulation. We are now able to evaluate the spectral quality of higher education standardized tests using confidence degrees, to highlight possible anomalies in the questions; and, after corrections, to evaluate the spectral impact of the improvements. This is the main contribution of our thesis to the improvement of procedures that control the quality of standardized tests and, by extension, to the improvement of the reliability of the students scores, which, in fine, constitutes the stake of our edumetric concerns. [less ▲]

Detailed reference viewed: 224 (18 ULg)
Full Text
See detailDéveloppement de modèles hydrosédimentaires pour la gestion de grands ouvrages hydrauliques
Dewals, Benjamin ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 23 (8 ULg)
See detailRégulation de l’expression de la nestine par les cellules souches mésenchymateuses en culture
Wislet-Gendebien, Sabine ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 31 (4 ULg)
See detailAspects de la toponymie des royaumes polynésiens d’Alo et de Sigave (îles Futuna et ʹĀlofi)
Delorme, Jérémie ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 14 (0 ULg)
Full Text
See detailDistributions des valeurs extrêmes
Donneau, Anne-Françoise ULg

Master's dissertation (2002)

Detailed reference viewed: 15 (2 ULg)
Full Text
See detailValidation et exploitation de nouvelles techniques d’imagerie numérique pour la caractérisation des profils comportementaux chez les poissons. Etude de l’influence de facteurs abiotiques et biotiques chez Symphodus ocellatus (Forsskål, 1775) et Chromis chromis Linné, 1758, Labridé et Pomacentridé méditerranéens
Ylieff, Marc ULg

Doctoral thesis (2002)

In many fields dedicated to behavioural research, digital imaging techniques (D.I.T.) now allow the conceptualisation of tools and systems from which the descriptive precision, the capabilities to detect ... [more ▼]

In many fields dedicated to behavioural research, digital imaging techniques (D.I.T.) now allow the conceptualisation of tools and systems from which the descriptive precision, the capabilities to detect, to analyse and to quantify behavioural parameters open original and very promising prospects. By the computing power offered by these new techniques, behavioural scientists have the possibility to quantify a large number of variables, which generally cannot be measured by usual methods of direct observation. The research works presented in this thesis, using new ethometric techniques based on D.I.T., concerned several questions relating to the study of effects of environmental factors on behavioural patterns in fish. By this way, we adjusted, experienced and operated complementary D.I.T. through field and lab researches. After a extensive general introduction devoted to D.I.T. developments and to its contributions in the study of animal behaviour, we present our works in two major parts. These two parts concern: 1.- Field studies conducted with the use of Digital Elevation Modelling (DEM) techniques and using classical methods of SCUBA diving direct observation of fish behaviour; 2.- Lab works using classical methods of direct observation and the techniques of computerised vision systems via the ETHOVISION® Color-Pro computerised video tracking system. The first part exposes research devoted to: Chapter 1 – the Use of DEM of natural aquatic habitats to characterised space and time utilisation modes during reproduction in the Mediterranean wrasse Symphodus ocellatus (Forsskål, 1775). The second part exposes research devoted to: Chapter 2 – the Study of effects of water temperatures and photoperiod (abiotic variables) on the display of reproductive behavioural patterns in the ocellated wrasse (Symphodus ocellatus) acclimated in large tank (5 M³ mesocosm) replicating a Mediterranean biotope; Chapter 3 – the Adjustment and the validation of the ETHOVISION® Color-Pro computerised video tracking system to the characterisation of behavioural patterns in aquarium swimming freely fishes. Study of effects of water temperature (abiotic variable) and congeners density (biotic variable) on spontaneous swimming behaviour in the Mediterranean damselfish Chromis chromis Linné, 1758. A general discussion mainly centred on new potential applications of digital imaging techniques to the fields of behavioural and environmental sciences, concludes this PhD dissertation. [less ▲]

Detailed reference viewed: 33 (5 ULg)
See detailContribution à l'étude du métabolisme de la contraction musculaire électro-induite chez l'homme
Vanderthommen, Marc ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 27 (1 ULg)
Full Text
See detailContributions to decision tree induction: bias/variance tradeoff and time series classification
Geurts, Pierre ULg

Doctoral thesis (2002)

Because of the rapid progress of computer and information technology, large amounts of data are nowadays available in a lot of domains. Automatic learning aims at developing algorithms able to produce ... [more ▼]

Because of the rapid progress of computer and information technology, large amounts of data are nowadays available in a lot of domains. Automatic learning aims at developing algorithms able to produce synthetic high-level information, or models, from this data. Learning algorithms are generally evaluated according to three different criteria: interpretability (how well the model helps to understand the data), predictive accuracy (how well the model can predict unseen situations), and computational efficiency (how fast is the algorithm and how it scales to large databases). This thesis explores two issues in automatic learning: the improvement of the well-known decision tree induction method and the problem of learning classification models for time series data. Decision tree induction method is an automatic learning algorithm which focuses on the modeling of input/output relationships. While this algorithm is among the fastest and most interpretable methods, its accuracy is not always competitive with respect to other algorithms. It is commonly admitted that this suboptimality is due to the excessive variance of this method. We first carry out an empirical study which shows quantitatively how important this variance is, i.e. how strongly decision trees depend on the random nature of the database used to infer them. These experiments confirm that this variance is detrimental not only from the point of view of accuracy but also from the point of view of interpretability. With the goal of improving both interpretability and accuracy, we consider three variance reduction techniques for decision trees. First, in the goal of improving mainly interpretability, we propose several methods which try to stabilize the parameters chosen during tree induction. While these methods succeed in reducing the variability of the parameters, they produce only a slight improvement of the accuracy. Then, we consider perturb and combine algorithms (e.g. bagging, boosting) which consist in combining the predictions of several models obtained by randomizing in some way the learning process. Inspired by the high variance of the parameters defining a decision tree, we propose an extremely randomized decision tree induction algorithm, called extra-tree, which chooses all parameters at random during induction. The aggregation of several of these extra-trees gives an important reduction of variance and this algorithm compares favorably in terms of accuracy and computational efficiency with both bagging and boosting. Because of the randomization of the parameters, the resulting method is also competitive with classical decision tree induction in terms of computational efficiency. In addition to these two approaches, we propose a ``dual'' perturb and combine algorithm which delays the perturbation at the prediction stage and hence requires only one model. In combination with decision tree, this method actually bridges the gap between single decision trees and perturb and combine algorithms. Of the first, it saves the interpretability (by using only one model), and with perturb and combine algorithm, it shares some of the accuracy (by reducing the variance). The second topic of the thesis is the problem of time series classification. The most direct way to solve this problem is to apply existing learning algorithms on low-level variables which correspond to the values of a time series at several time points. Experiments with the tree-based algorithms studied in the first part of the thesis shows that this approach is limited. A variance reduction techniques is then proposed specifically for this kind of data which consists in aggregating the prediction given by a classification model for subsequences of time series. Since this method does not provide interpretable models, we propose a second method which extends decision tree tests by allowing them to detect local shift invariant properties, or patterns, in time series. The study proposed in this part of the thesis is only a first step in the domain but our conclusions give some future work directions for handling complex type of data with automatic learning methods. [less ▲]

Detailed reference viewed: 254 (24 ULg)
See detailTemps et aspect en égyptien ancien. Une approche sémantique
Winand, Jean ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 23 (0 ULg)
Full Text
See detailPurificacao, caracterizacao e dosagem radioimunologica de glicoproteinas associadas a gestacao em zebuinos
Melo de Sousa, Noelita ULg

Doctoral thesis (2002)

The pregnancy-associated glycoproteins (PAGs) constitute a large family of aspartic proteinases expressed in the outer epithelial cell layer of the Artyodactyla placenta. In the first part of the present ... [more ▼]

The pregnancy-associated glycoproteins (PAGs) constitute a large family of aspartic proteinases expressed in the outer epithelial cell layer of the Artyodactyla placenta. In the first part of the present work, two biochemical approaches were used to characterize PAGs isolated from zebu (Bos indicus) fetal cotyledons. The first procedure, used to isolate PAG from zebu placenta removed late in pregnancy, included extraction of proteins at neutral pH, acidic and ammonium sulfate precipitations, anion and cation exchange chromatographies. The second procedure, used to investigate PAG in placentas removed at early and mid gestational periods, included protein extractions at acid or alkaline pH followed by pepstatin-A agarose affinity chromatography. A bovine PAG radioimmunoassay was used to monitor the immunoreactivity throughout the isolation procedures. The most immunoreactive fractions issued from cation exchange and affinity chromatographies were analyzed by SDS-PAGE and Western Blot, before transfer to polyvinylidene difluoride (PVDF) membrane for NH2-microsequence determination. By use of SDS-PAGE and Western Blot, different isoforms of PAG with apparent molecular masses from 51 to 69 kDa and isoeletric points varying from 3.1 to 6.7 were identified in placentas from different gestational ages. After CM ceramic chromatography of all except 0.32 M NaCl DEAE fraction, the most immunoreactive proteins revealed N-terminal amino acid sequences (10 to 25 aa long) which were 100% identical to bovine PAG-1. The same sequence (14 aa long) was found after pepstatin-agarose affinity chromatography of proteins extracted from placentas removed earlier in pregnancy. These results converged towards the expression of one major N-terminal PAG amino acid sequence in zebu placentas at different gestational ages. In the second part of this study, two specific RIA systems were developed then used to measure plasmatic PAG concentrations during gestation and postpartum period in Azawak zebu cows. Twelve females palpated per rectum and diagnosed as pregnant were bled at 5-10 days interval approximately from Week 8 of gestation till Week 10 postpartum (pp). One zebu cow initially diagnosed as pregnant showed PAG concentrations lower than the assay sensitivity (<0.20 ng/ml) and did not calve. Another cow showed abnormally high PAG concentrations during gestation, being excluded from the general PAG profile. The 10 other zebu cows gave a very homogeneous PAG profile. In these animals, concentrations increased progressively from Week 8 to Week 35 of gestation (from 6.04.2 to 196.034.8 ng/ml), remaining relatively constant until Week 39 (210.874.8 ng/ml), when they increased sharply to reach their highest level (1,095.6607.2 ng/ml) at parturition. After delivery, PAG concentrations declined significantly (P<0.05) till the Week 2 postpartum (348.4  85.6 ng/ml) and slowly till the Week 10 postpartum. These results revealed that PAG concentrations in zebu cattle were lower than those previously described in taurine breeds between week 35 and 39 of gestation. [less ▲]

Detailed reference viewed: 50 (1 ULg)
Full Text
See detailA study of noncovalent interactions by electrospray mass spectrometry
Gabelica, Valérie ULg

Doctoral thesis (2002)

This work describes a study of noncovalent interactions by electrospray mass spectrometry (ES-MS). In particular, we studied DNA duplexes, DNA complexes with drugs and cyclodextrin complexes with ... [more ▼]

This work describes a study of noncovalent interactions by electrospray mass spectrometry (ES-MS). In particular, we studied DNA duplexes, DNA complexes with drugs and cyclodextrin complexes with aliphatic acids. ES-MS experiments were performed on a hybrid quadrupole-TOF instrument and on an ion trap instrument. Basically two kinds of information can be obtained on the complexes. First, the full scan mass spectra give information on the composition of the solution that is injected, and therefore on the solution-phase stability of the complexes. We compare the ESMS data with the solution-phase data, and discuss the specificity of the observed complexes. The problem of nonspecific aggregation was encountered for the hydrophobic cyclodextrin complexes. We developed a new method for determining simultaneously the equilibrium association constant of [1:1] complexes and the ratio between the electrospray response factors of the complex and the free substrate. A change in the substrate conformation upon ligand binding can be detected by measuring the response factors of the complex and the free host. Second, the collision-induced dissociation of the complexes in the gas phase and the measurement of the amounts of fragments resulting from this dissociation give information on the gas phase kinetic stability of the complexes. It is shown that different collision regimes allow the system to fragment via different pathways, and that fast activation conditions favor the noncovalent dissociation of the complex because this process is entropy favored. The gas-phase kinetic stability measurements on series of homologous complexes suggest that intermolecular interactions like hydrogen bonding, electrostatic interactions, and stacking are conserved in the gas phase. Finally, on the basis of the results obtained on DNA duplexes, we propose a general multistep mechanism for the dissociation of noncovalent complexes. [less ▲]

Detailed reference viewed: 77 (5 ULg)
See detailDevelopment of a novel class of biodegradable (co)polyesters
Latere, Jean-Pierre

Doctoral thesis (2002)

Detailed reference viewed: 15 (5 ULg)
See detailRéactivité du tétroxyde d'osmium et des osmates vis-à-vis des séléniures et des sélénoxydes: application à la synthèse d'alcools allyliques et à la dihydroxylation énantiosélective d'oléfines
Colaux, Catherine ULg

Doctoral thesis (2002)

Ce travail traite de l’équilibre réactionnel établi entre le tétroxyde d’osmium et les séléniures d’une part et les osmates (VI) et les sélénoxydes d’autre part. La thèse se divise en trois grandes ... [more ▼]

Ce travail traite de l’équilibre réactionnel établi entre le tétroxyde d’osmium et les séléniures d’une part et les osmates (VI) et les sélénoxydes d’autre part. La thèse se divise en trois grandes parties : 1. L’oxydation des allylséléniures par l’AD-mix 2. L’utilisation des sélénoxydes comme oxydants des sels osmiques (VI) 3. L’établissement de l’existence de l’équilibre réactionnel précité La réaction d’oxydation des allylséléniures par l’AD-mix nous a permis de décrire une réaction dont la chemosélectivité dépend largement de la nature du groupement sélénié mais également de la nature et du degré de substitution de la double liaison. Nous avons au cours de ce travail comparé la réactivité d’une double liaison carbone-carbone comportant une espèce séléniée en position allylique avec celle de son homologue alkylé. Enfin, nous avons dans deux cas déterminé la stéréochimie absolue et relative des diols séléniés générés par oxydation des doubles liaisons carbone-carbone. L’utilisation des sélénoxydes comme co-oxydants des sels osmiques (VI) a conduit à un nouveau système de dihydroxylation catalytique énantiosélective d’oléfines générant dans tous les cas les diols correspondants avec de bons rendements chimiques et d’excellents excès énantiomériques. Une étude de l’influence exercée par la nature du sélénoxyde sur la réaction nous a permis d’une part de sélectionner le sélénoxyde le plus adapté à notre système mais également de déterminer l’étape limitante de vitesse. Enfin, nous avons posé les bases d’un système de dihydroxylation catalytique énantiosélective impliquant la génération in situ des sélénoxydes par oxydation du séléniure présent en quantité catalytique avec l’oxygène singulet généré photochimiquement. Enfin, nous avons démontré l’existence de l’équilibre reliant les quatre espèces (osmium (VIII), séléniure et osmate (VI), sélénoxyde). Cet équilibre a été mis à profit pour générer sélectivement des alcool allyliques. Dissertation doctorale en Sciences Chimiques Le 28 Janvier 2002 Laboratoire de Chimie Organique de Synthèse Promoteur : Prof. A. Krief [less ▲]

Detailed reference viewed: 13 (2 ULg)
Full Text
See detailMise en évidence de carences en oligo-éléments au sein de troupeaux bovins laitiers et viandeux en Wallonie
Guyot, Hugues ULg

Master of advanced studies dissertation (2002)

Basing on soil and forage analyses and on clinical signs, trace element deficiencies can be expected to occur in Wallonian dairy and beef cattle herds. The aim of this study was to evaluate the trace ... [more ▼]

Basing on soil and forage analyses and on clinical signs, trace element deficiencies can be expected to occur in Wallonian dairy and beef cattle herds. The aim of this study was to evaluate the trace element status of these herds and to determine whether differences could be demonstrated between dairy and beef herds. Thirty beef cattle herds and 26 dairy cattle herds that presented health problems or production disturbances underwent a close observation combined with blood samples taken from a sample of healthy animals in order to analyse zinc, copper, erythrocytes’ superoxyde dismutase and erythrocytes’ gluthathion peroxidase (selenium’s marker). Multiple deficiencies were detected in 84% of the herds. No significant difference was found between dairy and beef herds concerning the zinc and copper status, although a significant higher prevalence of selenium deficiency was shown in beef herds. Further studies are needed to demonstrate the impact of the deficiencies on animals’ health and production by re-evaluating these herds after trace element supplementation. [less ▲]

Detailed reference viewed: 45 (4 ULg)
See detailDe perceptie van het Poldernederlands in Vlaanderen
Perrez, Julien ULg

Master's dissertation (2002)

Detailed reference viewed: 52 (5 ULg)
See detailEtude du mode d'action d'hémicellulases ajoutées à un aliment riche en froment en alimentation aviaire : effet sur les performances zootechniques, la digestibilité des nutriments et la microflore intestinale
Vandeplas, Sabrina ULg

Master of advanced studies dissertation (2002)

Three experiments were conducted to investigate the effect of hemicellulase preparations on the performance parameters and the digestive physilogy of male broilers fed wheat-based diet from 1-32 d old ... [more ▼]

Three experiments were conducted to investigate the effect of hemicellulase preparations on the performance parameters and the digestive physilogy of male broilers fed wheat-based diet from 1-32 d old. The 5 dietary treatments were composed of a basal diet containing 60% (w/w) wheat (control) and 4 diets corresponding of the basal diet supplemented with enzyme preparations. Each diet was offered ad libitum. Two experiments were conducted for performances and digestibility measurements with 120 birds (24 birds/diet) in battery brooders housed in a environmentaly controlled room. Total collection of excreta was carried out from day 28 to day 32 post-hatching, for determination of apparent crude fat, Kjeldahl-nitrogen and crude cellulose digestibilities and for AMEn content of the diets measurement. The third experiment was conducted in pens frome day 7 to day 21. For each experimental diet, 16 birds were killed in 4 days for viscosity measurements in digesta. Addition of xylanase improve daily body gain by 1 to 6% without affecting ingestion of dry matter. Feed conversion ration increased by 1,5 to 4% with enzyme supplementation. Total apparent digestibilities of nitrogen, crude cellulose, crude fat and the content of AMEn in the 4 diets supplemented with enzymes increased significantly by an average of 1,6%, 59%, 1,7% and 2,8% respectively. Viscosity values were very variable between birds and seemed not correled to performances. However, digesta viscosity tend to decrease with enzyme addition, except for an enzyme (Grindazym G) wich induced an increase in the digesta viscosity for all the period of measurement. It is concluded from these experiments that improved performance parameters of broilers were more correled to the improvement of nutrients digestibility than to intestinal viscosity diminution. Digestion would be mainly improved by degradation of endosperm cell wall NSP and the subsequent release of the nutrients entrapped by the NSP structures, which induce more accessibility of nutriments to digestive endogenous enzymes of the birds. [less ▲]

Detailed reference viewed: 173 (7 ULg)
See detailLes TIC au cours de langues germaniques : s'en méfier ou les intégrer ?
Van Hoof, Florence ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 14 (5 ULg)
See detailLa clozapine, source d'inspiration pour les pharmacochimistes, les pharmacologues et les psychopharmacologues
Liégeois, Jean-François ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 11 (3 ULg)
Full Text
See detailCaractérisation pédogénétique et évaluation des sols en vue d’une gestion environnementale et d’un aménagement durable du terroir de Ticuantepe (Nicaragua)
Bah, Boubacar Billo ULg

Master's dissertation (2002)

This study has been carried out in Ticuantepe, south est of Managua, Pacific region of Nicaragua. The pedogenetical and agropedological factors of soil agricultural potentialities have been studied within ... [more ▼]

This study has been carried out in Ticuantepe, south est of Managua, Pacific region of Nicaragua. The pedogenetical and agropedological factors of soil agricultural potentialities have been studied within a sustainable development perspective. In a preliminary stage, the analysis of existing map informations have lead to the delimitation of a representative study zone and to the identification of three sectors and four geomorphopedological units within this zone. Four toposequences, in east-west directions, from Masaya Volcano to the Sierras spurs, were studied on the ground. This survey consisted in soil observations (augerings and pit profiles) as well as land use and crop types identification. Soil samples were collected for laboratory analysis. A conclusion of this study is the relatively young character of the soils, which developed from volcanic ashes or scoria. They are rich in glass but present few evidences of allophonic properties. The soils from north sector show the highest agricultural properties. To the opposite, the south sector appears to be the least suitable for agricultural management. The Central sector is a transitional area between South and North. A fertility gradient was identified as a result of the landscape shape and the distance from the Masaya Volcano. [less ▲]

Detailed reference viewed: 28 (6 ULg)
See detailDevenir médecin en République Démocratique du Congo. La trajectoire socioprofessionnelle des diplômés de l'Université de Lubumbashi
Rubbers, Benjamin ULg

Master of advanced studies dissertation (2002)

Ce mémoire se penche sur la trajectoire socioprofessionnelle des diplômés en médecine de l'Université de Lubumbashi des bancs de l'école à leur premier emploi.

Detailed reference viewed: 25 (3 ULg)
Full Text
See detailLe S.I.G. dans l'élaboration d'un projet d'aménagement du territoire : limites et capacités
Boutemadja, Abdelkader ULg

Master of advanced studies dissertation (2002)

Il s'agit d'estimer dans quelle mesure le SIG -outil puissant d'aide à la prise de décision - peut participer à l'élaboration d'un projet d'aménagement du territoire au service des urbanistes.

Detailed reference viewed: 156 (13 ULg)
Full Text
See detailAccord entre observateurs et coefficient Kappa de Cohen
Vanbelle, Sophie ULg

Master's dissertation (2002)

Detailed reference viewed: 64 (6 ULg)
See detailContribution à l'étude des propriétés du mazer
Martin, John ULg

Master's dissertation (2002)

Detailed reference viewed: 13 (4 ULg)
Full Text
See detailEssai sur le nucléole
Thiry, Marc ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 11 (1 ULg)
See detailAspectualité et actionalité. Essai sur la temporalité en égyptien ancien
Winand, Jean ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 44 (4 ULg)
See detailContribution fondamentale et clinique à l'exploration musculaire isocinétique
Croisier, Jean-Louis ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 76 (4 ULg)
Full Text
See detailMartial : Livre 7. Édition - traduction - commentaire
Polis, Stéphane ULg

Master's dissertation (2002)

Detailed reference viewed: 89 (10 ULg)
See detailImplication of follicular dendritic cells in prion diseases
Defaweux, Valérie ULg

Master of advanced studies dissertation (2002)

In prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein (PrPc) expression and the principal sites of the infectious agent (PrPres) accumulation in lymph organs. Two ways ... [more ▼]

In prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein (PrPc) expression and the principal sites of the infectious agent (PrPres) accumulation in lymph organs. Two ways of research has been considered: firstly, a new monoclonal antibody directed against bovine follicular dendritic cells (FDC-B1) developed in our laboratory has been characterised. We have shown that the antigen detected by FDC-B1 is expressed exclusively on FDCs surface of ruminants’ lymphoid organs. This protein seems to be a membrane glycoprotein of more or less 28 kDa whose sequence will be soon under determination. FDC-B1 will be a precious tool to detect FDC implication in scrapie infected sheep and in bovine spongiform affected cows. Secondly, the expression of PrPc isoforms has been analysed on bovine FDC depleted and enriched fractions and has been compared to bovine brain extracts. We demonstrated variation in the PrPc patterns of glycosylation between bovine FCD depleted and enriched cell populations. Moreover, glycosyl residues seemed to be different between immune and neuronal PrPc. As interaction of PrPc and PrPres appears to be a crucial pathogenic step promoted by homology, variation in PrPc glycoforms could explain the absence of infectivity in most bovine lymph organs affected by bovine spongiform encephalopathy. [less ▲]

Detailed reference viewed: 18 (4 ULg)
Full Text
See detail2D1/2 Thermal-Mechanical Model of Continuous Casting of Steel Using Finite Element Method
Pascon, Frédéric ULg

Doctoral thesis (2002)

The thesis deals with a numerical model based on the finite element method applied to the continuous casting of steel. The model is developed using the LAGAMINE finite element code and two industrial ... [more ▼]

The thesis deals with a numerical model based on the finite element method applied to the continuous casting of steel. The model is developed using the LAGAMINE finite element code and two industrial applications of steel casting are presented to illustrate the capabilities of the model. The first chapter introduces the continuous casting process, defining the essential terminology and the industrial challenges. Then, the objectives of the model are detailed: the model is applied to the upper part of the caster (in the mould region) as well as to the bending and straightening zones. Chapters two, three and four are dedicated to the theoretical developments of thermal aspects (phase transformations, thermal contraction, heat flow and thermal boundary conditions), mechanical aspects (generalized plain strain state, material constitutive law, ferrostatic pressure and mechanical contact) and the staggered analysis used for thermal / mechanical coupling. In the two next chapters, some numerical results are presented. The model has been first applied to a 125mm square billet in the mould region. The industrial goal is to evaluate the effect of the mould taper on the cooling of the billet (temperature evolution, solid shell growing, stress and strain development). The second application focuses on the risk of transverse cracking during straightening of steel slabs and the effect of some local defects (reduction of secondary cooling, locking or misalignment of rolls). The thesis ends with some concluding remarks and perspectives for the model. [less ▲]

Detailed reference viewed: 72 (17 ULg)
See detailHeidegger et la question de la chose. Esquisse d'une lecture interne
Dewalque, Arnaud ULg

Master's dissertation (2002)

Reconstruction génétique des réflexions de Heidegger sur le concept de "chose", en particulier sur sa portée métaphysique (par opposition au concept d'objet).

Detailed reference viewed: 21 (0 ULg)
Full Text
See detailKwantumveldentheorie met onbepaalde massa
Cattaert, Tom ULg

Master's dissertation (2002)

Detailed reference viewed: 28 (6 ULg)
See detailComparaison de logiciels pour l'étude par simulations de méthodes non paramétriques d'analyse de modèles à deux critères de classification.
Carletti, Isabelle

Master of advanced studies dissertation (2002)

Detailed reference viewed: 25 (7 ULg)
Full Text
See detailConception réalisation et test d'un support alternatif de cours : la technologie en ingéniorat de gestion
Degre, Aurore ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 21 (4 ULg)
See detailEtude comparative du chant imitatif de deux espèces du genre Acrocephalus : le phragmite des joncs (A. schoenobaenus) et la rousserolle effarvatte (A. scirpaceus).
Delcourt, Johann ULg

Master's dissertation (2002)

Nous avons réalisé, à partir d'échantillons de chants enregistrés sur le terrain, une étude comparative des capacités imitatives du phragmite des joncs et de la rousserolle effarvatte. Ces deux espèces ... [more ▼]

Nous avons réalisé, à partir d'échantillons de chants enregistrés sur le terrain, une étude comparative des capacités imitatives du phragmite des joncs et de la rousserolle effarvatte. Ces deux espèces occupant un habitat très similaire et vivant donc dans un environnement sonore comparable, nous avons postulé l'hypothèse que leurs caractéristiques imitatrices seraient similaires. Nous confirmons le caractère imitatif du chant chez les deux espèces (incorporation de motifs extraspécifiques). Cependant, nous avons mis en évidence que l'effarvatte présente moins d'imitations (environ 10 % de son répertoire) que le phragmite des joncs (40 % de son répertoire). Nous avançons une série de contraintes, au niveau physique, au niveau des capacités intrinsèques des espèces, au niveau social intra- et interspécifique, qui pourraient expliquer cette différence. Les contraintes les plus importantes semblent être la gamme de fréquence utilisés par l'imitateur et le processus de spéciation entre les deux espèces jumelles, la rousserolle verderolle et la rousserolle effarvatte. [less ▲]

Detailed reference viewed: 27 (2 ULg)
See detailL’histoire de la frontière interallemande – textes traduits
Letawe, Céline ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 17 (3 ULg)
See detailContribution à l'étude de la physiopathologie du diabète 2
Paquot, Nicolas ULg

Thèse d’agrégation de l’enseignement supérieur (2002)

Detailed reference viewed: 10 (0 ULg)
See detailRécits de vie : La honte comme biographème universel et singulier
Dawans, Stéphane ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 22 (0 ULg)
See detailLa Tour valenciennoise à Mons. Etude et projet de restauration.
Houbart, Claudine ULg

Master of advanced studies dissertation (2002)

Detailed reference viewed: 30 (1 ULg)
See detailL'énergie de chauffage et de climatisation en ville
Marique, Anne-Françoise ULg

Master's dissertation (2002)

Detailed reference viewed: 30 (2 ULg)
See detailLa nitrification dans le cadre du traitement des eaux usées: production de nitrites, préservation des nitrifiants et effet d'un support
Malchair, Sandrine ULg

Master's dissertation (2002)

Le monde actuel est confronté à de nombreux problèmes environnementaux résultant des activités anthropiques. Parmi ceux-ci se pose le problème de la pollution de l’eau. Veiller au maintien de la qualité ... [more ▼]

Le monde actuel est confronté à de nombreux problèmes environnementaux résultant des activités anthropiques. Parmi ceux-ci se pose le problème de la pollution de l’eau. Veiller au maintien de la qualité de l’eau devient une nécessité pour les sociétés humaines. Ce mémoire s’inscrit dans le cadre du traitement des eaux usées. Nous avons étudié le processus de nitrification, qui associé à la dénitrification, permet de diminuer l’impact de la pollution par l’azote. Ce mémoire s’inscrit dans le cadre d’un projet de la région wallonne qui étudie l’élimination de la charge azotée des eaux usées d’origine agricole par dans une première phase, le développement d’un procédé biotechnologique permettant de produire préférentiellement des nitrites ; pour ensuite, éliminer ceux-ci par dénitrification. La nitrification peut être définie comme étant la transformation biologique de composés organiques et inorganiques (NH4+) d’une forme réduite en forme plus oxydée (NO2-, NO3-). Ce processus peut être le fait d’organismes autotrophes et hétérotrophes. La présence de nitrate dans les cours d’eau peut provoquer l’eutrophisation de ces systèmes aquatiques entraînant des conditions anoxiques et la diminution de la diversité. Ce mémoire est composé de trois chapitres traitant chacun un aspect de la nitrification dans le traitement des eaux usées. Le premier chapitre tente de déterminer les conditions du milieu favorisant les bactéries responsables de la nitritation. Pour cela, des systèmes d’étude en continu sont mis en place. Lors de cette expérience, il est apparu nécessaire de toujours disposer d’inocula stables. C’est pourquoi, dans le second chapitre, nous avons testé différentes méthodes de préservation des populations bactériennes. Le dernier chapitre de ce mémoire étudie l’effet de différents supports sur la nitrification. Dans le premier volet de ce mémoire, les systèmes de culture en continu ont permis d’établir les conditions du milieu favorables à la production de nitrites. Ces conditions sont les suivantes : Concentration en N-NH4+ de 300 mg N/l, pH de 8.2 ± 0.2, température de 30°C et concentration en oxygène dissous inférieure à 2mg/l. Les paramètres les plus importants pour favoriser les populations bactériennes oxydant l’ammonium sont le pH et la teneur en oxygène dissous. Nous avons mis en évidence que les fluctuations de pH sont néfastes pour le maintien de la nitritation. Les teneurs en oxygènes dissous faibles (inférieures à 2mg/l) stimulent les bactéries oxydant l’ammonium mais n’affectent pas celles qui oxydent les nitrites. Le second volet de ce mémoire étudie les méthodes de préservation de la population nitrifiante afin d’envisager la méthode de stockage adéquate permettant à ces populations de maintenir leur activité nitrifiante. Les différentes méthodes de conservation envisagées sont les suivantes : conservation à court terme à 4°C, conservation à plus long terme à -20°C, -80°C ou par lyophilisation, en présence ou en absence de cryoprotecteurs (DMSO et glycérol). Il apparaît que les traitements employés ont des effets significatifs sur les taux de production de nitrites plus nitrates (p<0.05). La lyophilisation ne semble pas être une technique adéquate pour la préservation des nitrifiants. L’emploi de DMSO comme cryoprotecteur semble plus adéquat que l’emploi de glycérol. La conservation à court terme à 4°C semble appropriée aux nitrifiants. A plus long terme, la conservation à -80°C en présence de DMSO semble la plus adéquate aux populations de bactéries nitrifiantes. Le dernier volet de ce mémoire envisage l’effet d’un support sur la nitrification. Notre hypothèse de départ était que la présence d’un support favorise la nitrification. Dans le sol, les bactéries se lient fortement aux argiles. Nous avons utilisé quatre argiles comme support dans cette expérience. Nous avons employé, également des cubes de mousses de polyuréthane (grande surface pour que les bactéries se fixent) et de la craie (tamponner le milieu). Les traitements envisagés n’ont aucun effet significatif sur la production de nitrites plus nitrates (p> 0.05). Notre hypothèse de départ a été infirmée. Cependant, aucune inhibition due à la présence du support sur la nitrification n’est observée. En conclusion, nous pouvons dire qu’il est possible en ajustant le pH et la teneur en oxygène dissous de favoriser les populations de bactéries oxydant l’ammoniac et donc la production de nitrites. Les conservations à court et à long terme de populations nitrifiantes sont envisageables. La présence de support a maintenu la nitrification à un taux identique à celui observé pour des populations témoins sans support. Malgré leurs propriétés respectives, aucun support testé n’a favorisé la nitrification. [less ▲]

Detailed reference viewed: 95 (3 ULg)
See detailEstimation of additive and dominance genetic variances with Method R
Druet, Tom ULg

Doctoral thesis (2002)

Detailed reference viewed: 20 (11 ULg)
Full Text
See detailDistribution et comportement biogéochimique des métaux en trace dans les sédiments estuariens de l'Escaut.
Bouezmarni, Mohamed ULg

Doctoral thesis (2002)

L’objectif de cette étude est la détermination de la distribution et des propriétés des métaux traces dans les sédiments de l’estuaire de l’Escaut, en vue d’améliorer la compréhension de leur comportement ... [more ▼]

L’objectif de cette étude est la détermination de la distribution et des propriétés des métaux traces dans les sédiments de l’estuaire de l’Escaut, en vue d’améliorer la compréhension de leur comportement biogéochimique. Dans ce but, les distributions des éléments majeurs (Si, Al, Fe, Ca, Mg, Na, K, P, matières organiques et pertes au feu) et mineurs (Cd, Pb, Cu, Zn, Cr, Ni, Co, Mn et Li) ont été examinées dans 59 échantillons de sédiments de surface. L’analyse factorielle des résultats de la composition des dépôts montre que le processus de piégeage dans la zone de turbidité maximale constitue le facteur le plus important qui explique les teneurs des métaux traces dans les sédiments. De plus, la distribution de ces éléments a été étudiée dans différentes fractions granulométriques démontrant l’accumulation des métaux toxiques dans les fractions les plus fines. Elle permis de discuter de manière critique les méthodes de normalisation les plus utilisées dans la littérature et d’adopter la normalisation par le Li comme la méthode la plus adéquate dans le cas de l’Escaut, l’Al reste un bon élément de normalisation sauf pour les sables. La normalisation des concentrations métalliques des sédiments par le Li, montre une accumulation importantes du Cd, du Zn, du Cu, du Pb et du Mn limitée à la zone amont et un comportement conservatif pour le Cr, le Ni et le Co. Une étude de spéciation géochimique des solides a été réalisée par une nouvelle approche basée sur la titration acide des sédiments mis en suspension. Cette méthode permet, contrairement à la méthode de digestion sélective, de préciser la spéciation, la mobilité et la réactivité des métaux traces dans les sédiments. Les fractions les plus réactives des métaux étudiés sont notées dans le cas du Cd (80%), du Pb (70%), du Cu (70%), du Zn (80%) et du Mn (80%), notamment dans les vases anaérobiques de la zone amont. Le piégeage de ces métaux d’origine anthropogénique s’explique par la précipitation du Cd et du Zn sous forme de sulfures, la précipitation du Mn avec les carbonates et le recyclage du Pb avec les oxyhydroxydes de Fer à l’interface eau/sédiment. [less ▲]

Detailed reference viewed: 40 (8 ULg)
See detailContribution à l'étude de l'association possible entre pathologies parodontales et pathologies coronariennes
Geerts, Sabine ULg

Doctoral thesis (2002)

Etude clinique sur les associations entre les infections parodontales et la maladie coronarienne aiguë et/ou chronique: 3 groupes d'étude ont été constitués (paro et cardio sains; infarctus aigu du ... [more ▼]

Etude clinique sur les associations entre les infections parodontales et la maladie coronarienne aiguë et/ou chronique: 3 groupes d'étude ont été constitués (paro et cardio sains; infarctus aigu du myocarde; maladie coronarienne chronique) et comparés entre eux pour les différents facteurs de risque coronarien. Le risque d'être un coronarien aigu (infarctus aigu du myocarde) ou chronique est significativement associé à la présence d'une infection parodontale, la crise aiguë étant plus fortement corrélée à la parodontie sévère. De plus, le risque d'endotoxémie est lui aussi significativement plus grand chez les coronarien aigüs souffrant de parodontite. [less ▲]

Detailed reference viewed: 15 (7 ULg)
See detailLa question de l'autobiographie chez William Cliff
Hick, Anne-Laure ULg

Master's dissertation (2002)

Detailed reference viewed: 41 (2 ULg)
See detailProduit Fermier entre Qualification et Identité
Stassart, Pierre M ULg

Doctoral thesis (2002)

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailEtude et modélisation du transport et du piégeage des solutés en milieu souterrain variablement saturé. Evaluation des paramètres hydrodispersifs par la réalisation et l'interprétation d'essais de traçage in situ
Brouyère, Serge ULg

Doctoral thesis (2001)

The long term protection of groundwater resources implies to study the behaviour of water and contaminants as soon as they penetrate in the underground (recharge) until they leave it at natural outlets ... [more ▼]

The long term protection of groundwater resources implies to study the behaviour of water and contaminants as soon as they penetrate in the underground (recharge) until they leave it at natural outlets (discharge in surface water bodies, springs, …) or at artificial extraction points (pumping wells, …). During this residence in the underground, many physical and chemical processes are likely to play a role on contaminant mobility. The attenuation, retardation and auto-purification capacities of the underground medium have thus to be quantified and considered. Consequences of their effect on contaminant behaviour can be positive (contaminant dispersion, dilution, degradation, …) or negative (difficulties to recover the contaminant, long-term impact of the contamination, …). This research aims at providing a conceptual and mathematical framework for studying on the field and for modelling the migration and retardation of solutes in variably saturated underground media. A classification of physico-chemical processes is proposed, based on three main criteria : (1) a differentiation between “microscopic” processes, playing a role at pore-scale and “macroscopic” processes, playing a role at field scale, (2) a distinction between physical processes (affecting any kind of contaminant, independently from its chemical nature) and chemical processes (affecting some contaminants, according to their specific chemical properties), (3) a distinction between equilibrium processes (independent of time) and kinetic processes (explicitly dependent of time). On that basis, the conceptual model includes three main compounds : advection, hydrodynamic dispersion and a mass exchange process between the mobile water and an immobile phase of aqueous (dual porosity effect) or solid (kinetic sorption) nature. Within this conceptual framework, developments and adaptations made in the SUFT3D code in order to model the behaviour of a contaminant in the variably saturated underground are presented. The evaluation of hydrodispersive parameters governing the migration and the capturing of contaminants relies on the interpretation of field tracer tests, conducted under variably saturated flow conditions. An important part of the research has thus been devoted to an improvement of tracer test techniques and interpretation, more particularly in terms of concentration and mass recovery evolutions, the latter being more appropriate for evaluation and quantification of retardation processes. In order to model more physically and accurately the tracer injection, a new conceptual, mathematical and numerical approach has been developed, considering explicitly well-aquifer interactions. Using this model, numerical tests show the impact of tracer injection conditions on tracer test results, possibly leading to wrong interpretation in terms of both processes identification and parameters quantification. In order to make a correct interpretation of tracer test results, the control of tracer injection conditions is thus essential. Two experimental studies illustrate the developments of this work. A multi-tracer test experiment was conducted under saturated conditions in the sediments of the alluvial plain of the river Meuse at Hermalle-sous-Argenteau. The results of these tests allow to validate and to illustrate the approach developed in order to model accurately tracer injection and well-aquifer interactions, to highlight other practical and conceptual problems encountered when conducting the experiments, to examine the chemical behaviour of several artificial tracers and to quantify the hydrodispersive properties of alluvial deposits. The objective of the second field experiment was to identify and to quantify solute migration mechanisms in the unsaturated zone overlying the chalk aquifer in the Hesbaye Region. These results allow to suggest a unifying conceptual and mathematical approach in order to represent the hydrodynamic and hydrodispersive properties of fissured chalk under variably saturated conditions. They also show the impact of physical properties of aeolian loess materials on their hydrodynamic properties. [less ▲]

Detailed reference viewed: 131 (27 ULg)
See detailL'évolution du chlore inorganique au-dessus du Jungfraujoch et le Protocole de Montréal
Mahieu, Emmanuel ULg

Doctoral thesis (2001)

The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years ... [more ▼]

The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years. To achieve this, we have analyzed the observational database made of IR solar spectra recorded mainly with high resolution Fourier transform spectrometers installed at the International Scientific Station of the Jungfraujoch, located in the Swiss Alps, at 3580m altitude. The analysis of ATMOS (Atmospheric Trace Molecule Spectroscopy) data allowed us to first establish that HCl and ClONO2 account for more than 93% of the total inorganic chlorine, and that the summation of their vertical column abundances is an excellent surrogate of the Cly evolution at midlatitudes. Thus, we have derived HCl and ClONO2 total column abundance time series above the Jungfraujoch to analyze their temporal evolutions. Their combination has allowed us to show that the Cly increase between 1986 and 1995 (+50%) resulted primarily from the photodissociation of long-lived chlorinated source gas, in particular the manmade chlorofluorocarbons (CFC), progressively transported to the stratosphere after their release at the Earth surface during the seventies and the eighties. The organic chlorine (CCly) decrease in the troposphere resulting from regulations adopted by the Montreal Protocol, its Amendments and Adjustments, led to a progressive stabilization of Cly in the stratosphere. However, statistical analysis and interannual variability characterizing our time series, which extend to the end of 2000, prevent any final determination of the occurrence of the Cly maximum observed here at the end of October 1996, and of its subsequent decrease. We also show that chlorine partitioning among the chlorinated reservoirs has been durably influenced by heterogeneous processes which took place on stratospheric aerosols significantly enhanced following strong volcanic eruption of Mt Pinatubo (Philippines) in June 1991. The above-mentioned topics, complementary findings resulting from the study of the evolution of inorganic fluorine in the stratosphere, as well as comparisons other observational data bases and 2D model predictions are essentially discussed in Chapter 4. Before, Chapter 1 briefly reviews physical and chemical properties of the Earth atmosphere, and processes that control the state and erosion of stratospheric ozone. Individual contributions of chlorinated source gases to the CCly budget and their temporal evolution to the latter, inventory of Cly species, phase out schedule of chemical compounds covered by the Montreal Protocol and its Amendments and Adjustments are given in Chapter 2. Chapter 3 deals with instrumentation and data processing descriptions used to produce the geophysical data sets exploited in the main chapter of this work. [less ▲]

Detailed reference viewed: 33 (0 ULg)