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See detailHow does usability improve computer-based knowledge assessment?
Weinerth, Katja UL

Doctoral thesis (2015)

There has been a major shift from paper-and-pencil towards computer-based assessments (CBAs). CBA has the potential to overcome various limitations imposed by traditional assessment approaches, mostly ... [more ▼]

There has been a major shift from paper-and-pencil towards computer-based assessments (CBAs). CBA has the potential to overcome various limitations imposed by traditional assessment approaches, mostly because CBA allows for the easier and more effective measurement of complex knowledge concepts via the use of dynamic items. Innovative item formats in CBA (dynamic or interactive multimedia items) allow the assessment of complex skills (e.g., complex problem solving), but they also tend to increase the complexity of CBA instruments because of their augmented interactivity. If the CBA is not user-friendly, the test-taker might spend more time and effort trying to understand how to interact with the system instead of focusing on the assessment task itself. The research field of human-computer interaction (HCI) shows that the usability or user-friendliness of the system affects the interaction. Usability addresses how appropriate (for a particular use) or how user-friendly a CBA instrument is. Thus, to the extent that there is any detrimental technical bias in CBA affecting the user-friendliness of a CBA, it will affect the user’s interaction with the instrument and consequently the instrument’s psychometrics. There are certain guidelines (e.g., International Test Commission, 2005) that require usability testing to safeguard against the CBA instrument measuring skills or competencies other than those that are supposed to be measured by the CBA instrument. However, surprisingly little research has been conducted to investigate whether usability has been acknowledged in CBAs and whether researchers are aware of the impact usability might have on the assessment results. To answer these and further research questions, three studies were conducted within this present Ph.D. project. These studies focused on a specific CBA instrument: concept maps. A concept map is a graphical illustration of a knowledge concept and can be described as a “knowledge net.” Research has shown that the concept map is a valid and reliable instrument for measuring conceptual knowledge. Concept map instruments are a good example of the increasing popularity of CBA, as technology allows test-takers to correct and improve their concept maps with ease. Test-takers and their examiners receive immediate feedback on the correctness of the concept map. Furthermore, it is a good example of new approaches to knowledge assessment, which is currently a major trend. All of this taken together makes concept maps a good proxy for new ways of assessing knowledge. Our research builds on three studies (Study I – literature-based study, Study II – laboratory study, Study III – school study) that investigated the impact of usability on computer-based knowledge assessment using concept maps. Study I, a literature-based study, scrutinized the existing literature and answered the fundamental research question of whether and how usability has been acknowledged in CBA concept map studies. As no such literature review existed prior to the current project, a systematic literature review was conducted to shed light on the representation and relevance of usability displayed in CBA concept map studies. The literature review indicated that only 24 of 119 journal articles that assessed computer-based concept maps actually discussed the usability of the applied instrument in some way and only three of those 24 journal articles explicitly mentioned that they evaluated the usability of the applied instruments. The literature review illustrated that usability is rarely acknowledged and reported in CBA concept map studies. Our review brings to light the idea that the impact of usability, although well established in the field of HCI, has received insufficient attention in the field of educational assessment. Study II, a laboratory study, addressed the main research question of how HCI methods can be introduced to the field of educational assessment to improve the usability of a CBA concept map instrument. With a user-centered design and development approach, which makes the user the key reference, usability testing and heuristic analyses were conducted in the usability laboratory. The approved HCI methods of usability testing and heuristic analyses were combined to evaluate and further improve a CBA concept map instrument. We applied three iterative design and re-engineering cycles that were based on the results we received from the usability testing and heuristic analyses. To verify the improvements in the usability of the CBA concept map instrument, three independent and randomly assigned groups of 30 students underwent concept map assessments using the three iteratively developed instruments (baseline (V1), further developed: V2 and V3). The results of this independent design sample study showed that the HCI methods allowed us to design and develop demonstrably usability-improved concept map instruments; they furthermore revealed that the usability improvements significantly improved the assessment outcomes. Study III, a school study, empirically verified the impact that usability has on the psychometrics of the applied CBA instruments and on the satisfaction and performance of the test-takers. The experimental study was conducted at school, and 542 students were randomly assigned to one of the three CBA concept map instruments that showed consecutively improved usability. The performance of the test-takers who worked with the usability-improved instruments significantly increased in comparison with the baseline version. The test-takers indicated that they were more satisfied with the usability-improved instruments. Moreover, the internal consistency of the items from the baseline instrument in comparison with usability-improved instruments increased from a Cronbach’s alpha of .62 to .84. To summarize, Study I showed that the impact of usability is rarely evaluated and discussed in CBA concept map studies. Studies II and III clearly showed that usability has a positive impact on the test-takers’ interaction with the CBA concept map instrument. Specifically, Study II illustrated and demonstrated how HCI methods could be used to achieve usability-improved CBA instruments, which in turn allow for better assessment outcomes. In addition, Study III illustrated that the psychometrics were also affected by the usability of the instrument; specifically, the reliability (measured as the internal consistency of the applied items) increased when the usability-improved instruments were used. Thus, the continuing trend towards CBAs calls for more systematic usability research to help ensure satisfactory psychometric test properties and test-takers’ satisfaction with the instrument. The studies confirmed the hypothesis that if usability is not taken into account, the assessment results may severely compromise the quality of individual diagnostics as well as educational policies and educational decisions. [less ▲]

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See detailDo you speak numbers? The relation between language and numerical cognition through the prism of bilingualism and cross-linguistic investigations
Van Rinsveld, Amandine UL

Doctoral thesis (2015)

The overarching objective of the thesis was to investigate the link between numbers and language by examining numerical abilities in bilinguals and in cross-linguistic comparisons. I conducted my research ... [more ▼]

The overarching objective of the thesis was to investigate the link between numbers and language by examining numerical abilities in bilinguals and in cross-linguistic comparisons. I conducted my research mainly in Luxembourg where the educational context provides a highly standardized framework concerning age of acquisition and performance level achieved in the two school languages German and French. In Luxembourg, it is thus easily possible to directly benefit from very homogenous populations of highly proficient bilingual participants. Consequently this environment provides an exceptionally interesting framework to study numerical cognition and its relation to language. Firstly, two behavioral studies investigated numerical performances (i.e., magnitude judgments and arithmetic problem solving) in bilinguals at progressive stages of their bilingual language acquisition. More specifically, we used both within-subject and between-subject cross-linguistic comparison experimental designs on respectively bilingual and monolingual participants. Secondly, a short cross-linguistic comparison study assessed number transcoding skills in English- and French-speaking children in order to highlight the specific difficulties due to the use of French verbal numbers constructed on vigesimal structures. Thirdly, we adopted a more applied approach with outlooks towards direct educational outcomes for mathematical learning and teaching. We set up an experimental behavioral study that highlighted the importance of language context for efficient arithmetic problem solving in bilinguals’ second language. In a second study, we used a large-scale school assessment dataset to examine language effects on more complex mathematical problem solving. Finally, we used fMRI to identify the neural correlates underlying arithmetic problem solving in bilinguals’ languages and bring additional neuro-scientific insights into the field of language and numbers. [less ▲]

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See detailThe ex officio doctrine in European consumer law. A procedural tool reinvigorating individual consumer litigation
Beka, Anthi UL

Doctoral thesis (2015)

The thesis delves into the theoretical underpinnings of the establishment of the powers of national courts to raise pleas of Union consumer law of their own motion and examines the novel dimensions this ... [more ▼]

The thesis delves into the theoretical underpinnings of the establishment of the powers of national courts to raise pleas of Union consumer law of their own motion and examines the novel dimensions this opens for individual consumer litigation. In an extensive line of case-law the Court of Justice has built the principle of an active court in individual consumer litigation around the concepts of effectiveness of mandatory rules of consumer law and weaker party protection. Such understanding of judicial powers has been formulated, in certain circumstances, independently from the respective national procedural rules. The thesis analyses the question in terms of a Union consumer ex officio doctrine, presents its implications from a civil justice perspective and its important contribution for the effective judicial protection of consumers and Union citizens. [less ▲]

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See detailElectrodeposition of Chalcopyrites from Deep Eutectic Based Ionic Liquids
Malaquias, Joao Corujo Branco UL

Doctoral thesis (2015)

This thesis focuses on the electrodeposition of metal precursors from a deep eutectic based ionic liquid electrolyte and their annealing for Cu(In,Ga)(S,Se)2 thin film solar cells. Ionic liquids are ionic ... [more ▼]

This thesis focuses on the electrodeposition of metal precursors from a deep eutectic based ionic liquid electrolyte and their annealing for Cu(In,Ga)(S,Se)2 thin film solar cells. Ionic liquids are ionic compounds which are liquid at temperatures below 100 °C and contain no water. Therefore, by using an ionic liquid electroplating bath, the electrolysis of water is avoided and elements which are normally difficult to electrodeposit, such as gallium, can be easily deposited. In this sense, the electroplating current efficiency of the process (i.e. the energy efficiency of the process) is significantly improved by using an ionic liquid electrolyte instead of an aqueous electroplating bath. The objectives of this work are i) to electrodeposit Cu(In,Ga) metal precursors with high electroplating current efficiency, ii) to control the chemical composition of these precursors and iii) form Cu(In,Ga)(S,Se)2 absorber layers with adequate chemical composition and morphology for solar cell fabrication. In the frame of the third objective, it is intended to obtain absorber layers with a continuous gallium distribution as well. This last point is due to the fact that, during thermal annealing of metal precursors, gallium often segregates to the back of the absorber layer. Ultimately, this uneven gallium distribution can hinder the performance of solar cells. To meet these objectives, the co-electrodeposition of a) copper and indium, b) indium and gallium and c) copper, indium and gallium from an ionic liquid electrolyte is studied. The ionic liquid used in this work results from the 1:2 molar mixture of choline chloride and urea. From this work, the electrodeposition of Cu(In,Ga) metal precursors with an electroplating current efficiency above 75% was achieved. It was observed that the morphology of the electrodeposited precursors depended on the chemical composition of the electrolyte. In this frame, Cu(In,Ga) layers with dendritic or compact morphology were obtained. Precursors with dendritic morphology are not adequate, since this morphology persists after thermal annealing and ultimately results in devices with no efficiency. The chemical composition of the metal precursors can be controlled as well. Specifically, the gallium content of the metal precursor, which influences the optoelectronic properties of the absorber layer, was accurately tuned. The gallium content is usually expressed as the concentration ratio [Ga]/([Ga]+[In]) and could be tuned between 0.1 and 0.9. Therefore, the electrodeposition of Cu(In,Ga) metal precursors with high gallium content was achieved for the first time and would not have been possible without the use of an ionic liquid electrolyte. After subjecting the metal precursors to a thermal annealing, absorber layers with adequate chemical composition and morphology were obtained. Additionally, by employing a specific annealing routine developed at the Institute of Energy Conversion in the University of Delaware, absorbers with a continuous gallium profile and different gallium contents were obtained. It was observed that the performance of the solar cells was limited by the thermal annealing step and a maximum solar cell efficiency of 9.8% was achieved. In general, it can be concluded that different precursors require different thermal annealing routines in order to form quality absorber layers. [less ▲]

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See detailFingerprinting Techniques for Network Security
Lanze, Fabian UL

Doctoral thesis (2015)

Fingerprinting techniques aim to identify objects such as devices, data, users, or even attacks, based on distinctive characteristics. The goal of this thesis is to de- velop and evaluate methods for ... [more ▼]

Fingerprinting techniques aim to identify objects such as devices, data, users, or even attacks, based on distinctive characteristics. The goal of this thesis is to de- velop and evaluate methods for fingerprinting in different application domains and to contribute to a better understanding of fingerprinting in general. We concentrate on approaches that are applicable in practice to improve the security of computer networks. We first introduce a novel formal model of the central concepts of finger- printing in order to relate techniques to their particular application scenario. This model allows the comparison of approaches and the evaluation of their effectiveness for practical use. The evil twin attack in 802.11 networks is a severe security problem that nei- ther the industry nor the research community has found appropriate solutions for. Motivated by this threat, we develop novel fingerprinting methods. We address this challenge from two angles. In our first approach we exploit minuscule yet observable inaccuracies in crystal-oscillator-driven computer clocks. We will show that several conclusions drawn in the related research about the efficacy of this fingerprinting feature are false. We then enhance state-of-the-art approaches and for the first time provide a solution for remote physical device fingerprinting performed by typical off-the-shelf client devices that is able to mitigate the evil twin threat in practice. The second approach focuses on fingerprinting the behavioral characteristics of soft- ware tools that have been developed or can be misused to mount the attack. As we will show, our fingerprinting methods, which primarily exploit unavoidable low-level characteristics, allow the reliable detection of such an attack strategy within a few seconds. We then switch the perspective to the attacker’s side and investigate a finger- printing method that has been proposed to attack anonymization networks such as Tor by using traffic analysis, commonly referred to as website fingerprinting. We propose a novel approach that outperforms state-of-the-art methods in this area. We then evaluate for the first time the practical applicability of website fingerprinting in a realistic scenario, while avoiding simplified assumptions predominantly made in the related research. Our evaluation indicates that this particular threat, which is considered to be a serious security problem affecting many users, is not as severe as presumed. Therefore, concerns that have been raised and strategies for circumvent- ing this attack that have been proposed need to be reconsidered. [less ▲]

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See detailReceiver Antenna and Empirical Multipath Correction Models for GNSS Solutions
Sidorov, Dmitry UL

Doctoral thesis (2015)

The advent of the Global Navigation Satellite Systems (GNSSs), in particular, the U.S. Global Positioning System (GPS) and the Russia's GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS) have ... [more ▼]

The advent of the Global Navigation Satellite Systems (GNSSs), in particular, the U.S. Global Positioning System (GPS) and the Russia's GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS) have revolutionized geodesy by enabling a cheap and robust way of providing precise and continuous position estimates to users. Moreover, GNSSs have been shown to be extremely useful for a wide variety of other applications, in particular, geophysical, atmospheric, oceanographic studies, as well as industrial applications. Although the last two decades of GNSS exploitation were marked by great advances in accuracy and precision of the involved techniques, improvements can still be made. This thesis addresses the topic of receiver antenna and empirical multipath correction models, aiming to further improve GNSS solutions. GNSS utilizes measurement of ranges between satellites orbiting the Earth and receivers located on the Earth's surface through modulated electromagnetic signals. However, the actual point where the signal is received and which is denoted as a phase centre of an antenna, is not fixed, but varies depending on many parameters. Therefore, high-precision GNSS fundamentally depends on antenna phase centre corrections (PCC) and failing to accurately apply the latter results in biases and elevated uncertainties of estimated GNSS solutions. Additionally, due to repeating satellite-receiver geometry, these phase centre modelling deficiencies may lead to the generation of harmonic signals in the time series of the estimated parameters. In turn, identifying geophysical signals in the time series may be compromised by the presence of these artificial signals, resulting in inaccuracies in derived models. The geodetic community employs averaged (type-mean) PCC to estimate GNSS orbits, clock biases, tropospheric delays and other parameters, as well as to realize and provide access to the terrestrial reference frame. However, the use of individual PCC is beneficial for GNSS solutions, as it allows for more accurate estimation of satellite orbits and ground station coordinates. The latter is demonstrated using a regional network of 55 GNSS stations and processing the GPS data over a period of 10 years. Another topic addressed in this thesis concerns development of empirical site models (ESMs) using post-fit phase residuals accumulated over a period of time. These models are aimed to mitigate multipath and other unmodelled site effects that have a negative impact on GNSS solutions. Using a global network of stations the derived ESMs are evaluated for their capability to improve the GPS orbit determination as well as to increase the accuracy of ground station coordinate estimation. [less ▲]

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See detailLe fait internationalement illicite dans le temps: une question de procédure et de fond entre formalisme et activisme judiciaire
Komaïti, Maria-Vasileia UL

Doctoral thesis (2015)

Le fait internationalement illicite constitue l’objet d’appréciation de la juridiction internationale en vue de l’engagement de la responsabilité étatique. Or, la diversité des cas litigieux peut résulter ... [more ▼]

Le fait internationalement illicite constitue l’objet d’appréciation de la juridiction internationale en vue de l’engagement de la responsabilité étatique. Or, la diversité des cas litigieux peut résulter en une diversité de solutions et une flexibilité à l’approche du juge international. Cette souplesse s’illustre dans le dipôle entre formalisme et activisme judiciaire. Comme le pouvoir du juge ou arbitre international est conféré après consentement étatique au mécanisme judiciaire, il peut être rétréci selon une approche axée formellement sur le consentement étatique ou dilaté selon une approche fondée amplement sur d’autres critères. Un aperçu global sur le fond du comportement étatique est indispensable pour délimiter la violation internationale, la compétence de la juridiction internationale, définie principalement dans une phase préliminaire de la procédure, étant affectée. En particulier, l’argument de l’existence d’une violation continue qui persiste au moment de l’appréciation de l’affaire offre à la partie demanderesse la possibilité de contourner les règles régissant la procédure internationale. Parfois le concept de la violation continue peut être fictif, une pure invention théorique qui ne concourt qu’à l’insécurité juridique. Ainsi, le risque d’un excès du pouvoir juridictionnel est réel. Devant ce risque, l’étude essaie d’encadrer tant la constatation d’une violation internationale continue et sa réalisation que la compétence juridictionnelle pour la connaître ou la prendre en considération. Elle tente de dresser le contexte des concepts principaux, poser des critères différenciant l’instantanéité de la continuité de la violation et de fixer ses limites extrêmes. En plus, elle essaie d’identifier les conséquences de l’existence d’une violation continue sur l’engagement juridictionnel et, par conséquent, sur le pouvoir juridictionnel, dans une phase tant préliminaire que finale de la procédure internationale pour finalement examiner l’existence des méthodes alternatives afin que l’efficacité de la protection internationale ne soit pas compromise en raison de la sécurité juridique. [less ▲]

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See detailSprachkontaktinduzierte Variation im luxemburgischen Konsonantismus
Conrad, François UL

Doctoral thesis (2015)

The young Luxembourgish language shows a strong contact with neighbouring French and German. The analysis of variation patterns in words that can be described as “phonological doublets” – words with a ... [more ▼]

The young Luxembourgish language shows a strong contact with neighbouring French and German. The analysis of variation patterns in words that can be described as “phonological doublets” – words with a variable pronunciation, either in a ‘French’ or ‘German’ way – revealed that the influence of French on the (linguistic) structure of Luxembourgish is decreasing, while nativization processes and the raising influence of German increases the similarities between Luxembourgish and German at the phonetic-phonological level. As the comparison of three generations shows, this change happened over some 60 years only, with the elder generation using more variants close to the French pronunciation (e.g. [s]ymbol, Organisa[sj]oun), whereas the younger generation uses more variants close to the German pronunciation (e.g. [z]ymbol, Organisa[tsj]oun). The data gathered in a three-step experiment (translation from French and German into Luxembourgish, reading task, self-evaluation task) further revealed the flexibility of the Luxembourgish phonological system, strongly influenced by and converging to the French/German pronunciation in the translation task. Finally, the competences of the speakers in the neighbouring languages play another key role in explaining the choice of the variants, whereas the self-evaluation task showed that the variation is in many cases not conscious to the speakers. The study of language contact involving three (not only two, as in many other studies) languages gives new insights in the ways of which one language can influence another one, while the chosen quantitative/statistical framework (variable rule program following William Labov) revealed itself very constructive in the analysis of variation patterns in Luxembourgish. In a broader linguistic view, the results show the plenitude of new linguistic insights that can be found through the study of Luxembourgish, a language which can only be fully understood by consideration of the neighbouring languages as well. [less ▲]

Detailed reference viewed: 244 (23 UL)
See detailReconstruction of IRG1 Gene Regulatory Network in Mammalian Macrophages under Inflammatory Conditions
Tallam, Aravind UL

Doctoral thesis (2015)

The immune system is the first line of defence against invading pathogens. Macrophages are the key effector cells of the innate immune system which produce an array of cytokines, antimicrobial peptides ... [more ▼]

The immune system is the first line of defence against invading pathogens. Macrophages are the key effector cells of the innate immune system which produce an array of cytokines, antimicrobial peptides, and effector molecules pathogen in response to pathogen invasion. Immunoresponsive gene 1 (Irg1) is highly upregulated when mouse macrophages are stimulated with LPS. Recently, the function of Irg1 has been elucidated as a gene coding for a protein which catalyses the decarboxylation of cis-aconitate, a tricarboxylic acid (TCA) cycle intermediate, to itaconic acid. In turn, itaconic acid selectively inhibits isocitrate lyase, a key enzyme of the glyoxylate shunt, which is a saviour pathway for bacteria to grow on low carbon diets. Thus, Irg1 via the production of itaconic acid plays an important role in combating pathogen invasion. Despite the importance of this recent discovery, the upstream transcriptional machinery of IRG1 has not yet been investigated. Hence, the aim of this thesis was to elucidate the gene regulatory networks of IRG1 in mammalian macrophages under inflammatory conditions. To achieve this aim, the experimental protocols for the isolation of monocytes from peripheral blood and their differentiation into macrophages were implemented. The cells were then characterised based on their morphology and the expression profile of cellular marker genes to confirm their identity. Using this cellular model, I discovered IRG1 expression and itaconic acid production in human macrophages under LPS activation. Both IRG1 and itaconic acid were initially discovered elsewhere in murine macrophages upon LPS stimulation. I further analysed the dynamics of IRG1 expression and itaconic acid production using different bacterial and viral ligands in human and mouse macrophages, showing that IRG1 expression could be upregulated when mammalian cells encounter bacteria and viruses. Owing to the complex upstream transcriptional machinery for IRG1 expression, I implemented a workflow defined as transcription factor identification protocol (TFIP) using both experimental and computational methods to identify potential transcription regulators for IRG1 expression in human and mouse macrophages. siRNA mediated gene silencing experiments in human and mouse macrophages revealed IRF1 as a transcriptional regulator for IRG1 in both the species and CEBPB in mouse macrophages under LPS activation. [less ▲]

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See detailConfnement effects on a low molecular weight liquid
Djemour, Anna UL

Doctoral thesis (2015)

Investigation of the confinement of the epoxy resin DGEBA in nanopores using DSC, TMA and DS.

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See detailEnergetisches Regionalisieren. Transformationspraktiken der Energiewende am Beispiel der Biogaserzeugung
Faller, Fabian UL

Doctoral thesis (2015)

This doctoral dissertation examines geographical dimensions of the energy transition. It develops a conceptual framework for practice oriented transition studies in economic geography. Therefore, the ... [more ▼]

This doctoral dissertation examines geographical dimensions of the energy transition. It develops a conceptual framework for practice oriented transition studies in economic geography. Therefore, the energy transition is conceptualised as a socio-technical phenomenon and as a result of various practices. These practices (re)produce and transform the spatial contexts in which energy is produced and consumed. The main focus lies on the shift to renewable energies in so-called “energy regions”. There, various actors are involved in the operation of renewable energy facilities, such as operators, plant manufacturers, maintenance companies, planners, politicians, or local residents. The dissertation in hand illuminates the space-time dimension of these actors’ interplay, how their practices change over time and thereby constitute energy regions. The case of biogas co-fermentation exemplifies this “energetic regionalising”. Central findings are first, that knowledge exchange and creation of routines are central for regionalisations in the biogas sector. Second, in the case of renewable energies, different spatial concepts unfold meaning: Euclidian space as locale of resources, technologies and social discourse; relational space as platform for knowledge exchange as well as the creation and diffusion of routines, values and norms – that are embodied in practices of regionalisation. And third, regionalisations can be understood as practices and processes that contribute to the creation and stabilisation economic sectors. [less ▲]

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See detailDES INÉGALITÉS SOCIALES AUX DÉCÈS PAR SURDOSE AU SEIN DES USAGERS DE DROGUES ILLICITES
Origer, Alain UL

Doctoral thesis (2015)

Illicit and licit drugs’ misuse poses a serious threat to the health, safety and well-being of mankind. Social and health correlates of drug misuse are numerous and many of these can be reduced or avoided ... [more ▼]

Illicit and licit drugs’ misuse poses a serious threat to the health, safety and well-being of mankind. Social and health correlates of drug misuse are numerous and many of these can be reduced or avoided by improved prevention and intervention strategies. Our research analyses the association between socioeconomic inequalities and drug-related mortality. Four complementary studies have been conducted and the following results are to be stressed. Absolute national prevalence and prevalence rates of problem drug users have been increasing between 1997 and 2000 and declining from 2003 onwards. Luxembourg, with 6.16 problem drug users per 1,000 inhabitants aged between 15 and 64 years, is ranking among the 5 Member states showing the highest prevalence within the EU. In terms of drug-related mortality, 1.7 and 2.2 acute overdoses per 100,000 inhabitants have been registered nationally in 2011 and 2012, respectively. At EU level, Luxembourg stood for one of the highest fatal overdose rates in 2000, whereas in 2009 its prevalence fell below the EU average rate. Gender revealed to be a risk factor of drug-related mortality. We showed that the burden of deaths caused by fatal overdoses on the general national mortality was significantly higher for men compared with women. However, it appeared that female overdose victims whiteness remarkably different drug use patterns and trajectories than their male peers. Also, the time window between the onset of illicit drug use and its fatal outcome revealed to be shorter for women versus men included in our study. Early intervention in female drug users, routine involvement of first line health care providers and increased attention to poly- and psychotropic prescription drugs’ use might contribute to preventing premature drug-related death and reducing gender differences. Social and economic status of drug users impact on the occurrence of fatal overdoses. However, actual and self-referred socioeconomic characteristics of drug users may have a greater predictive value than the parental socioeconomic situation. Individual socioeconomic achievements seem to be more determinant in this context than trans-generational social status baggage. Our results suggest that measures aiming at improving educational levels, promoting vocational training and facilitating socio-professional (re)integration of drug users should, beyond their general objective of social insertion, completing conventional harm reduction strategies in order to increase their impact on public health, and eventually on the prevention of drug-related mortality. Our final study explored the cumulative effect of socioeconomic disadvantages on the probability of dying from an overdose of illicit drugs. Results showed that the risk of fatal overdoses increases proportionally with the accumulation of socioeconomic disadvantages and that, likewise in general morbidity and mortality, a social gradient seems also to be at stake when it comes to overdose-related mortality. These results suggest that any measure aiming at reducing social disparities may have a positive and dynamic impact that, even if isolated or targeted, counter the negative cumulative effect in terms of survival. Harm reduction services should integrate socially supportive offers, not only because of their general aim of social reintegration but crucially in order to meet their most important objective, that is to reduce drug-related mortality. This said, social parameters should not be seen as independent determinants and even more so should the concept of social inequalities be widened when applied to drug-related mortality. Although, the social status seems to hold a major role here, family, social and societal environments, as well as migration and acculturation contexts, also with a view on gender disparities, are at play in the attempt to explain differences in terms of morbidity and mortality. The future challenges for research will lie in the capacity to take into account the various demographical and societal mutations that next generations will experience and the way they will, or will not, succeed to share resources and distribute wealth in a ‘ healthy ’ way. [less ▲]

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See detailThe composite semiotics of interactional repair in French and Italian TV debates
Albanese, Claudia UL

Doctoral thesis (2015)

In this work, the composite semiotics of interactional repair is analysed across n=409 tokens of different repair types in French and Italian TV debates. Three methodologies are merged to understand if ... [more ▼]

In this work, the composite semiotics of interactional repair is analysed across n=409 tokens of different repair types in French and Italian TV debates. Three methodologies are merged to understand if variables correlate on the contextualisation of repair and how. Talk in interaction is transcribed and analysed following conversation analytic methods (Sacks et al., 1974). Acoustic analysis is run to detect average means, minimum and maximum pitches movements (Boersma and Weenink, 2014). Facial action units of the upper face are transcribed following the FACS methodology (Ekman and Friesen, 1983 and Ekman et al., 2002). In the datasets sampled, both French and Italian speakers produce AU 1+2 more often than other movements. The duration of facial action units is also considered. Action units (AU) below 500 ms and above 500 ms are distinguished. According to previous literature (Ekman, 1969), movements below 500 ms are involuntary. Data show that both in French and Italian, AUs are more frequently shorter than 500 ms on speech errors, cut offs, and edits and more frequently longer than 500 ms on recyclings and replacements. The movements preceding and following the AU in analysis are also analysed. When AUs at AU-1 and AU+1 differ in configuration or drastically in intensity with respect to the AU in analysis, the AU is said to be in prosodic break with respect to its surroundings thus a cue to the contextualisation of the action it accompanies usually a repair (or an increment repair). In n=409 instances of repair analysed, n=174 AUs in analysis are in prosodic break with both AU-1 and AU+1, and in half of these instances a maximal pitch accent correlates too. [less ▲]

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See detailBALANCING NON-FUNCTIONAL REQUIREMENTS IN CLOUD-BASED SOFTWARE: AN APPROACH BASED ON SECURITY-AWARE DESIGN AND MULTI-OBJECTIVE SOFTWARE DYNAMIC MANAGEMENT
El Kateb, Donia UL

Doctoral thesis (2015)

Beyond its functional requirements, architectural design, the quality of a software system is also defined by the degree to which it meets its non-functional requirements. The complexity of managing these ... [more ▼]

Beyond its functional requirements, architectural design, the quality of a software system is also defined by the degree to which it meets its non-functional requirements. The complexity of managing these non-functional requirements is exacerbated by the fact that they are potentially conflicting with one another. For cloud-based software, i.e., software whose service is delivered through a cloud infrastructure, other constraints related to the features of the hosting data center, such as cost, security and performance, have to be considered by system and software designers. For instance, the evaluation of requests to access sensitive resources results in performance overhead introduced by policy rules evaluation and message exchange between the different geographically distributed components of the authorization system. Duplicating policy rule evaluation engines traditionally solves such performance issues, however such a decision has an impact on security since it introduces additional potential private data leakage points. Taking into account all the aforementioned features is a key factor to enhance the perceived quality of service (QoS) of the cloud as a whole. Maximizing users and software developers satisfaction with cloud-based software is a challenging task since trade-off decisions have to be dynamically taken between these conflicting quality attributes to adapt to system requirements evolution. In this thesis, we tackle the challenges of building a decision support method to optimize software deployment in a cloud environment. Our proposed holistic method operates both at the level of 1) Platform as a service (PaaS) by handling software components deployment to achieve an efficient runtime optimization to satisfy cloud providers and customers objectives 2) Guest applications by making inroads into the design of applications to enable the design of secure systems that also meet flexibility, performance and cost requirements. To thoroughly investigate these challenges, we identify three main objectives that we address as follows: The first objective is to achieve a runtime optimization of cloud-based software deployment at the Platform as a service (PaaS) layer, by considering both cloud customers and providers constraints. To fulfill this objective, we leverage the models@run.time paradigm to build an abstraction layer to model a cloud infrastructure. In a second step, we model the software placement problem as a multi-objective optimization problem and we use multi-objective evolutionary algorithms (MOEAs) to identify a set of possible cloud optimal configurations that exhibit best trade-offs between conflicting objectives. The approach is validated through a case study that we defined with EBRC1, a cloud provider in Luxembourg, as a representative of a software component placement problem in heterogeneous distributed cloud nodes. The second objective is to ameliorate the convergence speed of MOEAs that we have used to achieve a run-time optimization of cloud-based software. To cope with elasticity requirements of cloud-based applications, we improve the way the search strategy operates by proposing a hyper-heuristic that operates on top of MOEAs. Our hyper-heuristic uses the history of mutation effect on fitness functions to select the most relevant mutation operators. Our evaluation shows that MOEAs in conjunction with our hyper-heuristic has a significant performance improvement in terms of resolution time over the original MOEAs. The third objective aims at optimizing cloud-based software trade-offs by exploring applications design as a complementary step to the optimization at the level of the cloud infrastructure, tackled in the first and second objectives. We aimed at achieving security trade-offs at the level of guest applications by revisiting current practices in software methods. We focus on access control as a main security concern and we opt for guest applications that manage resources regulated by access control policies specified in XACML2. This focus is mainly motivated by two key factors: 1) Access control is the pillar of computer security as it allows to protect sensitive resources in a given system from unauthorized accesses 2) XACML is the de facto standard language to specify access control policies and proposes an access control architectural model that supports several advanced access requirements such as interoperability and portability. To attain this objective, we advocate the design of applications based on XACML architectural model to achieve a trade-off between security and flexibility and we adopt a three-step approach: First, we identify a lack in the literature in XACML with obligation handling support. Obligations enable to specify user actions that have to be performed before/during/after the access to resources. We propose an extension of the XACML reference model and language to use the history of obligations states at the decision making time. In this step, we extend XACML access control architecture to support a wider range of usage control scenarios. Second, in order to avoid degrading performance while using a secure architecture based on XACML, we propose a refactoring technique applied on access control policies to enhance request evaluation time. Our approach, evaluated on three Java policy-based systems, enables to substantially reduce request evaluation time. Finally, to achieve a trade-off between a safe security policy evolution and regression testing costs, we develop a regression-test-selection approach for selecting test cases that reveal faults caused by policy changes. To sum up, in all aforementioned objectives, we pursue the goal of analysing and improving the current landscape in the development of cloud-based software. Our focus on security quality attributes is driven by its crucial role in widening the adoption of cloud computing. Our approach brings to light a security-aware design of guest applications that is based on XACML architecture. We provide useful guidelines, methods with underlying algorithms and tools for developers and cloud solution designers to enhance tomorrow’s cloud-based software design. Keywords: XACML-policy based systems, Cloud Computing, Trade-offs, Multi-Objective Optimization [less ▲]

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See detailDesign of point fitted insulating glass units
Tibolt, Mike UL

Doctoral thesis (2015)

Today’s building façades are not imaginable without the building material glass. Modern architects capitalise the transparency and the load carrying capacity of glass elements in the design of filigree ... [more ▼]

Today’s building façades are not imaginable without the building material glass. Modern architects capitalise the transparency and the load carrying capacity of glass elements in the design of filigree and light-flooded structures. Priority is thereby given to the maximal transparency and the energy efficiency of the glass façade. In fact, the strategy paper “EU 2020” formulated by the European Union has an important impact on the design of glass façade and the energy efficiency will be a focal point in the design of glass façades in future. The optimal combination of transparency and energy efficiency is achieved by using point fitted insulation glass units. Their application in glass façades becomes therefore indispensable in the future. <br />Currently, three different point fitting systems for point fitted insulation glass units exist. They however present several disadvantages concerning their installation procedure and the tightness of the glazing cavity. Additionally, a general design concept for point fitted insulation glass does currently not exist. In consequence, point fitted insulation glass is a non-regulated construction product and requires an approval in individual cases from the national building authorities. <br />A model to proof the structural integrity of a developed point fitted insulation glass unit with a suitable point fitting system and edge seal system is proposed. A state of the art investigation reveals the Fischer undercut anchor to be the most suitable type for the application in insulation glass. A novel design concept for point fitted insulation glass with undercut anchors is developed. The concept considers the determination of the climate loads and proposes a verification procedure for each structural element of the insulation glass unit. For this purpose, an existing climate load model for linearly supported insulation glass is analytically extended to the static system of point fitted insulation glass units with undercut anchors. For the verification of the connection undercut anchor in glass, an existing design method for point fitted single and laminated glazing is extended to point fitted insulation glass. Component tests are conducted on the Fischer anchor and its ultimate load bearing capacity in glass is determined. A calibrated numerical model of the proposed point fitted insulation glass unit with the Fischer anchor is developed for parametric studies. Large scale tests on the proposed new point fitted insulation glass unit are run with the aim to verify the numerical model, the climate load model and the extended design method and to proof the structural integrity of the entire unit. Finally a new point fitted insulation glass unit with a suitable point fitting type and a corresponding novel design concept is developed. [less ▲]

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See detailProving Regulatory Compliance: Business Processes, Logic, Complexity
Colombo Tosatto, Silvano UL

Doctoral thesis (2015)

The problem of proving regulatory compliance of a business process model is composed of two main elements. One of these elements is the business process model, which provides a formal compact description ... [more ▼]

The problem of proving regulatory compliance of a business process model is composed of two main elements. One of these elements is the business process model, which provides a formal compact description of the available executions capable of achieving a given business objective. The other element is the regulatory framework that the business process must follow, describing the compliance requirements given by the law or by a company’s own internal regulations. The problem consists of verifying whether a given business process model is compliant with the regulatory framework, which is carried out by verifying whether the executions of the model comply with the requirements of the regulatory framework. Solutions to prove the regulatory compliance of business processes have been already proposed in the past. Some solutions disregard the computational complexity aspect of the problem, while other solutions either solve a simplified version of the problem efficiently or provide approximate solutions for the general one. However, none of these solutions have formally studied the computational complexity of the problem of proving regulatory compliance. This thesis addresses that issue, showing in addition why efficient solutions of the general problem are not possible. In particular I study the computational complexity of a problem of proving regulatory compliance whose regulatory framework is defined using conditional obligations. The approach I adopt to represent the compliance requirement is semantically similar to some of the existing solutions proposed by other researchers, such as van der Aalst and many others, who adopts linear temporal logic over finite traces, or different variants of such temporal logic, to define the compliance requirements. More precisely, the approach used in the present thesis adopts propositional logic as base logic, and defines the semantics of the regulatory framework in a similar way as Process Compliance Logic introduced by Governatori and Rotolo. The study of the computational complexity of the problem is approached by dividing it in sub-classes and then combining their analysis to obtain the result for the target problem. The division is done according to three features of the regulatory framework. These features define whether the framework is composed of a single or a set of obligations, whether the obligations are conditional and whether violations can be compensated. These features can be omitted to identify simpler sub-classes of the problem. After having identified the different sub-classes of the problem, I study the computational complexity of some of these sub-classes and combine the results obtained to identify the computational complexity of the general problem tackled in the present thesis, where each of the three features identified are used to describe the compliance requirements. The results of the computational complexity analysis show that proving the existence of an execution of a business process compliant with the regulatory framework is an NP-complete problem. Differently proving that for all of the executions of a business process model, they are either compliant or not with the regulatory framework, is a coNP-complete problem. The results show that combining the two elements composing the problem of proving regulatory compliance, the process model and the regulatory framework, which are tractable when considered individually, leads to an intractable problem. In addition to the computational complexity results, the analysis provided in the thesis has also shown that tractable sub-classes of the problem, where the computational complexity is at most polynomial with respect to the size of the input, can be obtained by trivialising the expressivity of either one of the elements composing the problem. However the expressivity of these sub-classes is limited. Thus I identify a different tractable sub-class of the problem by weakening the expressivity of both elements composing the problem, but where each element is not trivialised as for the other sub-classes. Whether the sub-class identified can be considered expressive is arguable, however it represents a first step towards identifying a sub-class of the problem being both tractable and expressive, taking into account the limitation of employing propositional logic as base logic. [less ▲]

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See detailParentalité en situation vulnérable: trajectoires de résilience familiale?
Dujardin, Céline UL

Doctoral thesis (2015)

The present doctoral thesis focuses on the family and specifically parents in the domain of youth protection. This area covers the support for children in vulnerable situations which may have a negative ... [more ▼]

The present doctoral thesis focuses on the family and specifically parents in the domain of youth protection. This area covers the support for children in vulnerable situations which may have a negative impact on the child’s development. In contrast, the concept of resilience offers a perspective for a family trajectory which compensates for the danger to the child’s development and family functioning. In line with the goals of this study, first the theoretical framework is presented and definitions are provided for the concepts of parenting, vulnerability, resilience including the trajectory which brings the different concepts together. The aim of this project is to provide a frame of reference of reflection, based on four research question, concerning possible responses to the challenges faced by social services and families, while taking into account the specificities of the Luxembourgish context. The first research question addresses the different actors in area of youth protection and traces the policies which have evolved in dealing with families in difficult situations. The specific Luxembourg context is taken into consideration, by carrying out a discourse analysis in the area of youth protection. This analysis highlights the top-down approach by the actors in the field and points out social intervention policies aimed at improving social functioning. The second research question aims to identify factors contributing to resilience in parents facing a vulnerable situation. An exhaustive literature review was conducted, covering articles published in English, French and German. A qualitative meta-synthesis was carried out, resulting in a definition of the concept of family resilience and an identification of parental variables influencing the process of family resilience. The last two research questions concern families at risk and who therefore fall under the youth protection scheme. The study is based on the documentation by the enquêtes sociales (social surveys) conducted by the Service Central d’Assistance Sociale (SCAS) for 2006, 2009 and 2012. The analysis of this documentation reflects the evolution of the social work. Using quantitative methods, descriptive as well as exploratory analysis regarding family characteristics, risk factors and indicators, contributing to resilience could be identified. The thesis closes by proposing a summary conclusion which brings together the various findings from the different family histories within the system of youth protection and their potential in terms of family resilience. The discussion centers on the method of secondary analysis and the specificities of the Grand Duchy of Luxembourg. Finally, we highlight the additional knowledge gained through the project and point out several new perspectives for social policy development in the areas concerned. [less ▲]

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See detailCheating-Tolerance of Parallel and Distributed Evolutionary Algorithms in Desktop Grids and Volunteer Computing Systems
Muszynski, Jakub UL

Doctoral thesis (2015)

This thesis analyses the fault-tolerant nature of Evolutionary Algorithms (EAs) executed in a distributed environment which is subjected to malicious acts. Such actions are a common problem in Desktop ... [more ▼]

This thesis analyses the fault-tolerant nature of Evolutionary Algorithms (EAs) executed in a distributed environment which is subjected to malicious acts. Such actions are a common problem in Desktop Grids and Volunteer Computing Systems (DGVCS’s) utilising idle resources shared by volunteers. Due to the vast computational and storage capabilities provided at a low cost, many large-scale research projects are carried out using such set-ups. However, this advantage is obtained at the expense of a challenging, error prone, heteroge neous and volatile environment of execution. In the volunteer-based systems, such as BOINC, the incentives offered to the contributors attract also malicious users, commonly called cheaters. A cheater typically seeks to obtain the rewards with little or no contribution at all. Additionally, this group may also include "crackers" or "black hat hackers" - users motivated by nothing more than a pure satisfaction from violating computer security. In this study we use and formalise cheating faults - a model for the behaviours described above, which are a subtype of byzantine (arbitrary) faults. They are mainly characterised by the alteration of outputs produced by some or all tasks forming a distributed execution. The approach differs from the arbitrary faults in its implementation, as usually they are introduced intentionally and from within the boundaries of a system. The innate fault resilience of EAs has been previously observed in the literature. However, this PhD manuscript offers the first, formal analysis of the impact of cheating faults in this area of optimisation techniques. In particular, the following contributions are proposed: - An in-depth formal analysis of the cheating-tolerance of parallel Evolutionary Algorithms (EAs), including proofs of convergence or non-convergence towards valid solutions in the presence of malicious acts. A step-wise approach is used, focusing firstly on the most simple variant of an EA that is still of theoretical and practical interest, i.e. a (1 + 1) EA. Then the results are extended to regular (population-based) EAs. The analysis shows that the selection mechanism is crucial to achieve convergence of EAs executed in malicious environments. - The extension of the study to cheating-resilience of spatially-structured Evolutionary Algorithms (EAs) and gossip protocols. More precisely, we analyse Evolvable Agent Model (EvAg) relying on Newscast protocol to define neighbourhoods in the evolution and the communication layers. There, we provide the necessary conditions for convergence of the algorithm in a hostile environment and we show that the evolutionary process may be affected only by tampering with the connectivity between the computing resources. After that, we design an effective connectivity-splitting attack which is able to defeat the protocol using very few naive cheaters. Finally, we provide a set of countermeasures which ultimately lead to a more robust solution. These results have been published in several international, peer-reviewed venues and well recognized international journals. By the variety of problems addressed by EAs, this study will hopefully promote their usage in the future developments around distributed computing platforms such as Desktop Grids and Volunteer Computing Systems or Cloud systems where the resources cannot be fully trusted. [less ▲]

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See detailEssays on Benchmarking Credit Performance
Michala, Dimitra UL

Doctoral thesis (2015)

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See detailGreening Local Economies: Nature Parks as Instruments for Sustainable Regional Development
Feyeh, Franklin Bahfon UL

Doctoral thesis (2015)

ABSTRACT The proliferation of Nature Parks in Europe and the change in the function of these areas has brought forth questions about the meaning and extent to which Nature Parks encourage practices for ... [more ▼]

ABSTRACT The proliferation of Nature Parks in Europe and the change in the function of these areas has brought forth questions about the meaning and extent to which Nature Parks encourage practices for regional sustainable development. As such, research into this subject is ongoing. Since the creation of the first Nature Park in Europe some five or six decades ago, today, the functions of many of these areas have metamorphosed; triggered by increasing knowledge about the importance of existing ecosystem services in park areas, on adjacent local inhabitants. Consequently, parks have moved from areas of pure conservation to areas that combine environmental preservation with other socioeconomic demands in regional development. When this multifunctional characteristic is fixed into various regional policies, Nature Parks are generally interpreted by policy makers as necessary tools for realizing sustainable development in local areas. For the fact that parks have assumed new functions, it is certain, there are modifications in the strategies adopted for managing these areas. As a result, this study holds that the strength of Nature Parks in mitigating resource depletion, to improve socioeconomic prosperity and participatory regional processes, in rural areas in Luxembourg, is explicitly linked to the development strategies intended for these areas. The study draws on two official Nature Parks in Luxembourg (Haute Sûre and Our), to explain contemporary strategies to simultaneously integrate activities of ecological conservation, economic development, social well-being and resource governance. Therefore, the study sticks on the concept of green economy, an integrated notion in the framework of sustainable development, as for example, promoted by United Nations Environment Programme (UNEP, 2011), to draw a line between theory and practice of Nature Park development in Luxembourg. To comprehend the role and impacts of Nature Parks in regional development, the study has been guided by a qualitative methodology. Methods were chosen based on flexibility and the strength to provide useful insights about parks’ activities. This provided responses to the main research question; to what extent are strategies contributing to the appreciation of Nature Parks by local, regional and national stakeholders, as instruments for greening local economies, for the purpose of attaining sustainable regional development in Luxembourg? The dissertation presents different dimensions in which Nature Parks in Luxembourg are trying to promote regional sustainability. It made use of chapters that describe and analyse ecological policies for improving ecosystem services. This is mainly guided by schemes for environmental education, biodiversity contracts and agricultural advice that convey modernisation into traditional agricultural practices. Undeniably, approaches affixed for the development of Nature Parks have been contributing in reshaping local economies. Not only are these strategies important in integrating economic development and ecological conservation, but also, the outcomes via innovative and diversified projects have fairly improved approaches for local production. A new rural identity is now being developed, standing tall as the main strength behind the marketing of locally branded Nature Park products. Apart from the fact that organic production is still a matter of controversy, concrete social policies are lacking while local participation in Nature Parks’ activities is a critical challenge and absolutely insufficient. Away from researching on the ecological, economic, social and governance approaches for greening Nature Parks, the study has also explained certain challenges caused mainly by, but not limited to, differences between stakeholders in conceptualising Nature Parks as tool for local/regional development. The emerging drawbacks from these limitations vis-à-vis regional projects are enough reason to rethink the extent to which Nature Parks in Luxembourg encourage sustainable regional development. The research reasons that attaining sustainable development in Nature Parks is a critical challenge. This can be most effective if predestined strategies logically integrate aspects of environmental conservation, economic prosperity and social well-being, including attractive policies of regional governance. [less ▲]

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See detailBody perception and evaluation in anorexia nervosa
Lutz, Annika UL

Doctoral thesis (2015)

Body image disturbance is a prominent feature in anorexia nervosa (AN) and encompasses alterations across the different dimensions of body image, that is, perception, affect, cognition, and behaviour ... [more ▼]

Body image disturbance is a prominent feature in anorexia nervosa (AN) and encompasses alterations across the different dimensions of body image, that is, perception, affect, cognition, and behaviour. There is a wealth of research regarding the subjective experience of body image disturbance and evidence for underlying neuronal alterations is beginning to emerge. The present project was designed to assess basic processes underlying body image disturbance with the help of psychophysiological measurement techniques and self-other discrimination tasks. In study 1, using a self-other discrimination task with distorted body images, we were able to demonstrate interactions between perceptual factors and cognitive bias which may sustain a distorted and negative body image in healthy women. Study 2 showed a discrepancy between explicit negative ratings for body shapes and implicit neutral affect towards the same images, as assessed with an affective startle-modulation paradigm, in healthy women and women with AN. These results suggest that automatic fear responses to fat-distorted self-body pictures, as well as implicit approach motivation towards thin body images, as reported in previous studies, are not present in all patients with AN. In study 3 a differential alteration of featural and configural visual processing of body images was detected in an event-related brain potentials (EEG-ERP) paradigm. Individuals with AN showed a lack of discrimination between self-body and self-object pictures between 105 and 160 ms after stimulus onset (P1 component, featural processing) and an enhanced processing of body relative to neutral object pictures between 160 and 225 ms after stimulus onset (N1 component, configural processing). This suggests alterations in the basic visual processing of body shapes in AN, which might be related to influences of top-down attentional modulation. Study 4 showed enhanced processing of cardiac visceral signals in the central nervous system (CNS) in individuals with AN, which might either be a marker of psychopathology, in particular anxiety, or an indication of clinical improvement. In summary, the present results do not support the view of a global perceptual deficit in AN, but demonstrate the complexity of body image alterations in AN. It appears mandatory to further investigate basic processes underlying body image disturbances in AN and in healthy women to arrive at a comprehensive understanding of their nature and to provide a theoretical basis for body image interventions. The importance of using specific assessment methods, such as indicators of body-related processing in the CNS, is highlighted. [less ▲]

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See detailCOMPUTER-ASSISTED INTERVENTIONS TO IMPROVE SELF-REGULATION IN PATIENTS WITH SELF-REGULATORY DEFICITS
Campillo Costoya, Cristina UL

Doctoral thesis (2015)

The aim of the present thesis was to examine the efficacy of computer-assisted interventions in increasing self-regulation. Recent studies indicate that self-regulation is associated with executive ... [more ▼]

The aim of the present thesis was to examine the efficacy of computer-assisted interventions in increasing self-regulation. Recent studies indicate that self-regulation is associated with executive function, mood disorders and heart rate variability (HRV). In Study 1, we investigated the efficacy of the use of the visual software Tic-Tac tool in reducing anxiety-related behaviours during transition periods in three adults with autism and learning difficulties. Recently it has been suggested that anxiety-related behaviours in autism are associated with emotion regulation deficits. The results of this study revealed that all three participants showed a reduction in anxiety-related behaviours such as stereotypies and nervous utterances from baseline to intervention phase. In Study 2, we investigated the effects of heart rate variability biofeedback (HRV BF) on mood and executive function in healthy volunteers, while contrasting different formats of HRV BF presentation. One group of participants completed 7 sessions of a computer-based HRV biofeedback while another group attended 10 sessions. No significant differences were found between groups. However, only Group 2, which completed 10 training sessions, showed an improvement in depression symptoms after intervention. Significant improvements were also found in positive mood, emotion regulation and flexibility at post-intervention in Group 2. In addition, this group showed an increase in positive mood and HRV indices (SDNN, Total HRV) from pre- to post-session levels. Group 1 showed a significant decrease in negative affect and an increase in HRV parameters (SDNN, Total HRV, LF HRV) across sessions. In Study 3, we examined the effects of 12 sessions of HRV BF in 21 stroke patients. Participants were assessed using cognitive tasks and self-report two times before (extended baseline) and two times after the intervention (follow-up). While this study was not able to demonstrate that HRV BF improved long-term cognitive performance or affective state in stroke patients, short-term increases of mood after training suggest that this intervention may be useful to increase emotional well-being in stroke patients. In addition, stroke patients showed increases in HRV indices (RMSSD, SDNN, LF HRV, LF/HF ratio, total HRV) from pre- to post-training session. These findings are in line with previous studies, in which no long-term effects could be observed. In addition, in study 3, emotion dysregulation was found to be associated with mood disorders. Strong correlations were also found between mood before training and changes in HRV indices from pre- to post-training. These findings advance our knowledge on the association between mood and self- regulation. In summary, these studies suggest that healthy participants, and clinical populations (e.g. stroke patients and individuals with autism) can improve self-regulation through computer-based interventions. These methods may, therefore, be useful adjunct treatments for the improvement of self-regulation. [less ▲]

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See detailDesign and Analysis of Secure Exam Protocols
Giustolisi, Rosario UL

Doctoral thesis (2015)

Detailed reference viewed: 58 (4 UL)
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See detailAn empirical analysis of the luxembourg mutual fund market place
Irek, Fabian UL

Doctoral thesis (2015)

Detailed reference viewed: 141 (19 UL)
See detailEssays on Dynamic Economic Analysis
Tabakovic, Amer UL

Doctoral thesis (2015)

Detailed reference viewed: 234 (42 UL)
See detailNovel Methods for Learning and Adaptation in Chemical Reaction Networks
Banda, Peter UL

Doctoral thesis (2015)

State-of-the-art biochemical systems for medical applications and chemical computing are application-specific and cannot be re-programmed or trained once fabricated. The implementation of adaptive ... [more ▼]

State-of-the-art biochemical systems for medical applications and chemical computing are application-specific and cannot be re-programmed or trained once fabricated. The implementation of adaptive biochemical systems that would offer flexibility through programmability and autonomous adaptation faces major challenges because of the large number of required chemical species as well as the timing-sensitive feedback loops required for learning. Currently, biochemistry lacks a systems vision on how the user-level programming interface and abstraction with a subsequent translation to chemistry should look like. By developing adaptation in chemistry, we could replace multiple hard-wired systems with a single programmable template that can be (re)trained to match a desired input-output profile benefiting smart drug delivery, pattern recognition, and chemical computing. I aimed to address these challenges by proposing several approaches to learning and adaptation in Chemical Reaction Networks (CRNs), a type of simulated chemistry, where species are unstructured, i.e., they are identified by symbols rather than molecular structure, and their dynamics or concentration evolution are driven by reactions and reaction rates that follow mass-action and Michaelis-Menten kinetics. Several CRN and experimental DNA-based models of neural networks exist. However, these models successfully implement only the forward-pass, i.e., the input-weight integration part of a perceptron model. Learning is delegated to a non-chemical system that computes the weights before converting them to molecular concentrations. Autonomous learning, i.e., learning implemented fully inside chemistry has been absent from both theoretical and experimental research. The research in this thesis offers the first constructive evidence that learning in CRNs is, in fact, possible. I have introduced the original concept of a chemical binary perceptron that can learn all 14 linearly-separable logic functions and is robust to the perturbation of rate constants. That shows learning is universal and substrate-free. To simplify the model I later proposed and applied the ``asymmetric" chemical arithmetic providing a compact solution for representing negative numbers in chemistry. To tackle more difficult tasks and to serve more complicated biochemical applications, I introduced several key modular building blocks, each addressing certain aspects of chemical information processing and learning. These parts organically combined into gradually more complex systems. First, instead of simple static Boolean functions, I tackled analog time-series learning and signal processing by modeling an analog chemical perceptron. To store past input concentrations as a sliding window I implemented a chemical delay line, which feeds the values to the underlying chemical perceptron. That allows the system to learn, e.g., the linear moving-average and to some degree predict a highly nonlinear NARMA benchmark series. Another important contribution to the area of chemical learning, which I have helped to shape, is the composability of perceptrons into larger multi-compartment networks. Each compartment hosts a single chemical perceptron and compartments communicate with each other through a channel-mediated exchange of molecular species. Besides the feedforward pass, I implemented the chemical error backpropagation analogous to that of feedforward neural networks. Also, after applying mass-action kinetics for the catalytic reactions, I succeeded to systematically analyze the ODEs of my models and derive the closed exact and approximative formulas for both the input-weight integration and the weight update with a learning rate annealing. I proved mathematically that the formulas of certain chemical perceptrons equal the formal linear and sigmoid neurons, essentially bridging neural networks and adaptive CRNs. For all my models the basic methodology was to first design species and reactions, and then set the rate constants either "empirically" by hand, automatically by a standard genetic algorithm (GA), or analytically if possible. I performed all simulations in my COEL framework, which is the first cloud-based chemistry modeling tool, accessible at http://coel-sim.org. I minimized the amount of required molecular species and reactions to make wet chemical implementation possible. I applied an automatized mapping technique, Soloveichik's CRN-to-DNA-strand-displacement transformation, to the chemical linear perceptron and the manual signalling delay line and obtained their full DNA-strand specified implementations. As an alternative DNA-based substrate, I mapped these two models also to deoxyribozyme-mediated cleavage reactions reducing the size of the displacement variant to a third. Both DNA-based incarnations could directly serve as blue-prints for wet biochemicals. Besides an actual synthesis of my models and conducting an experiment in a biochemical laboratory, the most promising future work is to employ so-called reservoir computing (RC), which is a novel machine learning method based on recurrent neural networks. The RC approach is relevant because for time-series prediction it is clearly superior to classical recurrent networks. It can also be implemented in various ways, such as electrical circuits, physical systems, such as a colony of Escherichia Coli, and water. RC's loose structural assumptions therefore suggest that it could be expressed in a chemical form as well. This could further enhance the expressivity and capabilities of chemically-embedded learning. My chemical learning systems may have applications in the area of medical diagnosis and smart medication, e.g., concentration signal processing and monitoring, and the detection of harmful species, such as chemicals produced by cancer cells in a host (cancer miRNAs) or the detection of a severe event, defined as a linear or nonlinear temporal concentration pattern. My approach could replace “hard-coded” solutions and would allow to specify, train, and reuse chemical systems without redesigning them. With time-series integration, biochemical computers could keep a record of changing biological systems and act as diagnostic aids and tools in preventative and highly personalized medicine. [less ▲]

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See detailComputer Simulations of Crystallization Mechanism in Polymeric Materials
Anwar, Muhammad UL

Doctoral thesis (2014)

In this work, we have studied crystallization in short polymer chains using molec- ular dynamics simulations. We use a realistic united atom model which is able to reproduce the physical quantities ... [more ▼]

In this work, we have studied crystallization in short polymer chains using molec- ular dynamics simulations. We use a realistic united atom model which is able to reproduce the physical quantities related to phase transitions. We present a study of crystal nucleation from undercooled melts of n-alkanes and identify the molec- ular mechanism of homogeneous crystal nucleation under quiescent conditions and under shear flow. We choose n-eicosane (C20) the length of which is below the en- tanglement length and n-pentacontahectane (C150) the length of which is above the entanglement length so that we can compare results for unentangled and entangled polymer chains. We also provide the crystal growth mechanism of n-eicosane under quiescent conditions. For C150, we present crystal lamellae structure and compare our results with published simulation results. We use a mean first passage time analysis and a committor analysis to determine the critical nucleus size and then to compute the nucleation rate. We observe that the critical nucleus is of cylindrical shape. We report on the effects of shear rate and temperature on the nucleation rates and estimate the critical shear rates, beyond which the nucleation rate in- creases with the shear rate. We show that the critical shear rate corresponds to a Weissenberg number of order unity which is in agreement with previous experimen- tal observation and theoretical work. We also show that the power law behaviour between nucleation rate and shear rate is in agreement with experiments and theory. We compute the viscosity of the system during the formation of crystalline nuclei and we show that the viscosity of the system is not affected by the crystalline nuclei. Finally, we present results of crystallization in the polyethylene (C500) melt under quiescent conditions. [less ▲]

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See detailLaser Annealing of CuInSe2 Electrodeposited Precursors as the Absorber Layer in Thin Film Solar Cells
Meadows, Helen UL

Doctoral thesis (2014)

This thesis demonstrates a method by which a non-vacuum deposited CuInSe2 precursor is transformed into a semiconductor absorber layer, suitable for completion into a photovoltaic device, using 1 s laser ... [more ▼]

This thesis demonstrates a method by which a non-vacuum deposited CuInSe2 precursor is transformed into a semiconductor absorber layer, suitable for completion into a photovoltaic device, using 1 s laser annealing. A final device produced using this absorber fabrication method gave a 1.6 % best conversion efficiency. This represents the first reported working device originating from electrodeposition - laser annealing. In this thesis, the steps taken to achieve this result are analysed in detail. This work is split into four parts. Firstly, the precursor structure and the optical properties of its component materials were investigated to ensure optimal interaction between the laser beam and sample. Using the selected codeposited CuInSe2 precursor it was shown that it is possible to stimulate grain growth and atomic diffusion by using a 1064 nm Nd:YAG laser with only a 1 s annealing time. Secondly, it is shown that even on these rapid annealing time-scales the thermodynamic equilibrium reactions between the ternary CuInSe2 and its constituent materials must be considered. This is proven by the formation of the first device from a laser annealed absorber only when a sufficiently elevated partial pressure of Se is supplied during the annealing process. Absorbers formed under lower Se activities led to devices which were shunted or showed negligible efficiency. A correlation was identified between the Se partial pressure and the absorber properties including its Se content, grain size and PL yield. Thirdly, a finite element model capable of predicting the film temperature during laser annealing is demonstrated. By considering the Gaussian nature of the irradiating beam it is seen that the peak temperature of the CuInSe2 film, which formed the 1.6 % device, fluctuated spatially by > 300 oC during processing. Variations in temperature led to different rates of atomic diffusion and grain growth and resulted in lateral inhomogeneities in the absorber. The low device efficiency is believed to be partially caused by these variations. Finally, the chemical composition of the film and its effect on absorber properties is established. Increasing the Cu/In ratio of CuInSe2 precursors and incorporating Na into CuInSe2 absorbers is shown to increase their crystal coherence length. However, the positive effects related to these elements must be balanced against their impact on the optoelectronic properties of the absorber when present in high concentrations. Therefore it is hoped that this initial ‘first device’ efficiency validates this fabrication route and motivates future research on this interesting topic. [less ▲]

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See detailL'a priori, l'a posteriori, le pur et le non pur chez Christian Wolff et ses maîtres
Neveu, Sébastien Adrien Charles UL

Doctoral thesis (2014)

This work tries at first, in a structural part, to understand the coherence and to estimate the solidity of the " marriage between the reason and the experience " that Christian Wolff tried to establish ... [more ▼]

This work tries at first, in a structural part, to understand the coherence and to estimate the solidity of the " marriage between the reason and the experience " that Christian Wolff tried to establish in philosophy, by means of the concepts of a priori, of a posteriori, the pure and the not pure. It demonstrates while this "alliance" is not bearable and engenders an important tension in the whole of its thought, what engenders a historic crisis concerning the metaphysics, the crisis ending historically in the criticism of Kant. In a more historic, second part, this work tries to go back up at the origin of the use of these concepts (a priori, a posteriori, pure and not pure) at the predecessors of Wolff (Tschirnhaus, Leibniz, Weigel, Sturm, Agricola, Descartes, Ramus, etc.) to establish that the concept of pure reason is far from making the unanimity in the classic thought, that it stirs up controversy and that it is in complete opposition with the Aristotelian and scholastic tradition. This work thus allows in the end to question a history of the official philosophy based on the classic interpretation stemming from Kant. [less ▲]

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See detailModelling and global analysis of transcript profiles reveals dynamic roles for microRNAs in transcriptional networks controlling lineage commitment.
Liivrand, Maria UL

Doctoral thesis (2014)

Controlled maintenance of multipotent stem cells is a key component for the development and sustainment of complex multicellular organisms. Various signalling pathways contribute to these processes being ... [more ▼]

Controlled maintenance of multipotent stem cells is a key component for the development and sustainment of complex multicellular organisms. Various signalling pathways contribute to these processes being either lineage specific or more ubiquitously distributed over different tissue types. Transcription factors are considered as the primary propagators of signals that induce multipotent precursor cells to differentiate into specified cell types. These processes are required to revolve in a constrained and timely manner, with different cell types using variable sets of transcription factors and time scales. microRNA molecules represent an efficient and specific class of regulatory non-coding RNA molecules that efficiently constrain and specify differentiation cascades. New findings suggest that various endogenous non-coding RNA species, whose expression is governed through elaborate transcription factor networks, contribute to the regulation of genomewide transcriptional output. Here, evidence is presented of microRNA and transcription factor connectivity during differentiation cascades. First, these two classes of RNA regulatory molecules are shown to share a common target, lipoprotein lipase, and exert dynamical regulation over its expression during adipogenic differentiation. Second, investigating the genome-wide initial events of adipogenic and osteoblastic lineage commitment cascades reveals extensive transcription in non-protein-coding genomic regions. Further analysis of a select cohort of these non-coding transcripts allows for inferring transcription factor binding dynamics through enhancer-related RNA sequences as well as suggests a more wide-spread role for long non-coding RNA species in regulating transcriptional output. These findings contribute to unravelling basic transcriptional circuitry during cellular transitions. [less ▲]

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See detailThe right to good administration at the crossroads of the different sources of fundamental rights in the EU integrated administrative system
Mihaescu, Bucura Catalina UL

Doctoral thesis (2014)

The right to good administration as it stands today is both a general principle of EU law (hereafter GPL) and a fundamental right codified in the Charter of Fundamental Rights of the EU. The present ... [more ▼]

The right to good administration as it stands today is both a general principle of EU law (hereafter GPL) and a fundamental right codified in the Charter of Fundamental Rights of the EU. The present contribution provides the case study of good administration at the confluence of these two vectors of protection and highlights that there are instances where, even in relation to what might appear to be the same right, there are overlaps and sometimes clear differences as regards its content and level of protection according to its interpretation as a GPL or a CFR right. This study points out that the divergences stemming from the interplay of these two fundamental rights’ sources may, in certain instances, take the form of actual or potential conflicts, giving rise to inevitable “gaps” in protection. This makes the insurance of individuals’ rights dependent on the level of protection conferred by the source which is held to prevail, leading therefore to many inconsistencies and deficiencies from the standpoint of the rule of law. Having been conducted within a context marked by the entry into force of the Lisbon Treaty which - by giving binding legal force to the CFR, added a supplementary layer to the already existing “symphony of sources” – this study is a contribution to the debate on the difficult coexistence of the multiple sources of fundamental rights in the EU legal system. The reality of this coexistence gives rise to a large number of questions: How should one order the plurality of sources of law?” How do the various layers of protection interact? What is the relation between them in case of conflict? Are there instances where the outcome of a case is likely to be different depending on the invocation of a certain source of law rather than another; in other words, are there any existing or potential “gaps” in protection? If so, how may such gaps be filled up? Which source is to be relied on in priority, is there a hierarchy among them? Which would be the impact of such a hierarchical order of review with regard to individuals’ protection? Is there any room in the EU legal order for an alternative model of review, capable of supplementing the hierarchical approach? Which alternative model would be the most suited in order to confer an adequate and coherent protection of individuals’ fundamental rights? Assessed with regards to the more particular example of the right to good administration, these interrogations frame the main question of this study: Does the codification of the right to good administration in Article 41 CFR usurp the broader protection provided by the EU Courts under the GPL status of the notion? In other words, may the general principle of good administration take over where the scope of protection of the Charter’s right to good administration ends? The present contribution will highlight that the scope of protection of the right to good administration and of the various procedural rights codified under its “umbrella” in Article 41 CFR is defined in a significantly more restricted manner than their protection as general principles of EU law, being therefore likely to lead to multiple “gaps” in protection. Having in view the important practical need to ensure a “consistent” compliance with individuals’ fundamental rights - inter alia the right to good administration -, this study will argue for a dynamic approach of interpretation of sources, for a “pluralistic” – as opposed to a “hierarchical” – understanding of the relationship between the various layers of protection in the EU legal order, which will be called the “lexical order of review” . This approach – which implies a continuing reliance on the GPL vector of protection - is the best suited to confirm the seriousness of the EU commitment to fundamental rights . Besides this main purpose of assessing the principles of good administration at the confluence of their various sources, the present study further seeks to put forward the real interest and vast potential of the right to good administration in the EU legal order and especially in the context of “composite” administrative proceedings . With this objective in mind, the general introductory part of this study will be devoted to the analysis of the recognition, development, content and scope of application of the general principle of good administration. Such an overview is indispensable in order to highlight the real potential of this principle. This contribution further seeks to supply an answer to those who still question the need of a right to good administration in the EU legal order . In this regard, without denying that the right to good administration does not have an independent judicial life of its own – but merely exists via its sub-components which are now listed in Article 41 CFR - this study will demonstrate that the gathering of those principles under the “umbrella” of the right to good administration is likely to have vast potential for the protection of individuals in the EU administrative space. First, the present contribution suggests that by assimilating individuals’ rights during the administrative procedures to those enjoyed in judicial proceedings, the right to good administration leads to a sort of “judicialisation” of the administration , being capable of ensuring procedural justice, public administrative adherence to the rule of law and sound outcomes for administrative procedures. It is commonly agreed in this regard that adequate protection of procedural rights at the administrative level may have a positive impact for both individuals and the good functioning of the EU system as a whole; as prevention is better than cure, so good administration is better than remedies for bad administration . In this vein, although a remedy is normally available at the judicial level, on multiple occasions, the solution arrives too late to prevent harmful consequences for the individual concerned. Such a risk may be “prevented” by a proper protection of individuals’ rights at the administrative level. On the other hand, the achievement of sound administrative decisions in which individuals’ procedural rights are complied with may necessarily have a positive impact in terms of the proper functioning of the EU judicial apparatus in that it is likely to significantly decrease the workload of the EU Courts . In this way, the principle of good administration may be useful for the good administration of justice . Second, this study will demonstrate that since the landmark TUM decision , the right to good administration has established a “bridge” between the discretionary powers of the EU administrative authorities and the protection of individuals in administrative proceedings. The principle of good administration appears to act as a counterweight to the discretionary powers of the administrative players in that it induces the latter, when adopting decisions within their important powers of appraisal, to take the rights of individuals into account. In this way, both the “objective” and “subjective” rationales of the principle of good administration - namely the efficiency and rationality of the administration, on the one hand and individuals’ procedural protection, on the other hand, – are concomitantly complied with . Third, this contribution further seeks to highlight the potentiality of the right to good administration to fill the “gaps” of individual protection and to solve problems of legitimacy in the reality of the dynamically developing EU “integrated” administrative system – also known as “composite” administrative procedures - where decisions are taken with inputs from both national and EU administrative authorities, each using different procedural rules. The present study will illustrate that the “composite” nature of the right to good administration, by the strength stemming from the interaction of its sub-elements renders this “umbrella” right capable of ensuring the protection of individuals’ procedural rights within such “composite” administrative procedures . Consequently, the right to good administration may be held to constitute the key element of the integrated administrative system, the individual’s “ticket” for the protection of his procedural rights in the context of multi-level proceedings. Finally, this study will highlight that the right to good administration has vast potential in becoming a “trust-enhancing principle” and in bringing citizens closer to the EU institutions . Indeed, by placing the individual at the center of preoccupations of the EU administration, by seeking to ensure the fairness of the administration and the corresponding adequate procedural protection of individuals, the right to good administration is likely to become a key element in ensuring citizens’ trust in the EU institutions and in improving the latters’ legitimacy . It is probably this “trust” rationale of the right to good administration which has determined the enhanced procedural protection of “interested third parties” in certain administrative proceedings . Indeed, in some instances, the EU Courts overstepped the formal conception of the strict standing rules , in order to give primacy to the procedural protection of interested third parties . It is therefore not excluded that in the long run, the right to good administration become the privileged instrument for the protection of interested third parties in administrative proceedings. [less ▲]

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See detailHolistic, Autonomic, and Energy-aware Resource Allocation in Cloud Computing
Guzek, Mateusz UL

Doctoral thesis (2014)

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See detailEssays on the Euro zone Sovereign Debt Crisis and Financial Markets
Perego, Erica UL

Doctoral thesis (2014)

This thesis analyses the euro zone sovereign crisis from a macroeconomic perspective with a focus on the interaction between sovereign risk, financial markets and the real economy at the euro area ... [more ▼]

This thesis analyses the euro zone sovereign crisis from a macroeconomic perspective with a focus on the interaction between sovereign risk, financial markets and the real economy at the euro area currency union-wide level. The first part consists of an empirical study on the euro zone asset markets. It computes and analyses the dynamic comovements of stock and sovereign bonds for the core and the periphery of the euro zone focusing on the geographical and asset dimension of the markets. This comprehensive approach allows shading new light on European financial markets with respect to studies that focus at only one dimension. Results suggest that further economic integration would be desirable but that, at the moment, Europe is a tale of two regions. The second part of the thesis consists of two chapters dealing with the modeling of the euro zone financial markets and the study of the international transmission of shocks. Chapter 3 focuses on the international transmission of sovereign debt default and looks at the spillover from the periphery to the core region via financial intermediaries. The study of the structure of the banking sector suggests the desirability of more banking integration for the euro area welfare. Chapter 4 expands the model of Chapter 3 by introducing international equity markets. This framework allows exploring the relation between financial intermediaries and asset markets for the euro zone. Results point to the key role of this interaction as a driver of the time varying stock-bond correlation. [less ▲]

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See detailDie Handwerker und Zünfte der Stadt Luxemburg im Spätmittelalter
Jullien, Eva UL

Doctoral thesis (2014)

The PhD thesis seeks to explore the social structure of the craftsmen of the town of Luxembourg in the 14th and 15th centuries, employing a fourfold perspective: Based on the municipal account books ... [more ▼]

The PhD thesis seeks to explore the social structure of the craftsmen of the town of Luxembourg in the 14th and 15th centuries, employing a fourfold perspective: Based on the municipal account books, guild statutes, and the documents of local religious institutions, which contain information on the townspeople’s loans, it analyses the crafts’ institutional framework, their economic conditions, their individual public influence as well as their social relations. The first part of the thesis examines the guilds of medieval Luxembourg and the different functions they fulfilled within urban society, more precisely: their handling of commercial regulations, of apprenticeship and female work, their religious and military activities as well as their political participation and cultural orientation. Thereafter the financial condition of the individual trades is explored by evaluation of a tax list, the artisans’ activities on the local bond market and their investments in the rent of urban revenues. The third chapter takes a closer look at craftsmen who came into prestigious positions in the town government. Apart from analysing their individual, social and professional background it also determines whether certain guilds provided more prestige and political influence than others. By comparing the situation before and after the year 1443, the chapter furthermore asks whether Philip of Burgundy’s conquest of the town and its subsequent integration into the Burgundian Netherlands led to a change in the guilds’ distribution of power. The fourth and last part examines the social relations of Luxembourgian craftsmen. Through application of the method of Social Network Analysis on a dataset of hundreds of individuals it investigates the correlations between a person’s trade and their choice of neighbourhood or of marriage and business partners. Thus the research does not only contribute to the exploration of the social structure of a middle-sized town, but also to the mechanisms which came into effect in the formation of medieval urban societies. [less ▲]

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See detailInterweave/Underlay Cognitive Radio Techniques and Applications in Satellite Communication Systems
Sharma, Shree Krishna UL

Doctoral thesis (2014)

The demand for precious radio spectrum is continuously increasing while the available radio frequency resource has become scarce due to spectrum segmentation and the dedicated frequency allocation of ... [more ▼]

The demand for precious radio spectrum is continuously increasing while the available radio frequency resource has become scarce due to spectrum segmentation and the dedicated frequency allocation of standardized wireless systems. This scarcity has led to the concept of cognitive radio communication which comprises a variety of techniques capable of allowing the coexistence of licensed and unlicensed systems over the same spectrum. In this context, this thesis focuses on interweave and underlay cognitive radio paradigms which are widely considered as important enablers for realizing cognitive radio technology. In the interweave paradigm, an unlicensed user explores the spectral holes by means of some spectrum awareness methods and utilizes the available spectral availabilities opportunistically while in the underlay paradigm, an unlicensed user is allowed to coexist with the licensed user only if sufficient protection to the licensed user can be guaranteed. Starting with a detailed overview of the existing techniques, this thesis provides contributions in both theoretical and the practical aspects of these paradigms. This thesis is structured into two main parts as described below. One of the important capabilities required for a cognitive radio transceiver is to be able to acquire the knowledge of its surrounding radio environment in order to utilize the available spectral opportunities efficiently. The higher the level of information it can acquire, the better becomes the spectrum utilization. In this context, the first part of this thesis focuses on spectrum awareness techniques such as spectrum sensing, signal to noise ratio estimation and sparsity order estimation which are useful for realizing interweave and underlay based cognitive transceivers as well as a hybrid cognitive transceiver, which overcomes the drawbacks of both the above approaches. The effects of noise and channel correlations, which are often neglected in the existing literature, are considered in our analysis. In the above context, firstly, we propose new sensing thresholds for the eigenvalue based sensing approach using recent results from random matrix theory in order to achieve the improved sensing in correlated scenarios. Then we study the signal to noise ratio estimation problem for both narrowband and wideband transceivers with the help of a detailed theoretical analysis under the signal plus noise hypothesis for a range of correlated scenarios. Subsequently, we study the problem of compressive sparsity order estimation in order to estimate the sparsity order of the carrier occupancy over the wide spectrum using a compressive sensing approach. In addition, we carry out the performance analysis of a hybrid cognitive transceiver which combines the spectrum sensing approach with a power control-based underlay approach. The second part of this thesis introduces the concept of cognitive satellite communications which is a rather unexplored area in the literature despite its significant benefits to both satellite and terrestrial operators. This concept has been motivated due to the limited availability of the satellite spectrum as well as the continuously increasing demand of broadband multimedia, broadcast and interactive satellite services. Subsequently, we study the applications of various cognitive radio techniques in satellite communication systems focusing on the following two scenarios: (i) Hybrid cognitive satellite communication which deals with the spectral coexistence of satellite systems with the terrestrial systems, and (ii) Dual cognitive satellite communication which deals with the spectral coexistence of two satellite systems operating over the same coverage area. Understanding the characteristics of coexisting systems is of great importance while applying a suitable cognitive radio technique. In this context, this thesis exploits the specific characteristics of satellite systems in order to map a suitable cognitive radio technique to a specific scenario. For hybrid cognitive scenarios, we propose the following enabling techniques: (a) Interference modeling, (b) Harmful interference detection, (c) Cognitive beamforming including both transmit and receive beamforming, and (d) Dual-polarized spectrum sensing. Similarly, for dual cognitive scenarios, we propose the following techniques: (i) Cognitive interference alignment, (ii) Cognitive beamhopping, and (iii) Dual-polarized spectrum sensing. Finally, we provide interesting open research issues in the considered domain. [less ▲]

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See detailThe effect of interphases created by Al2O3 nanoparticles in styrene butadiene rubber
Sushko, Rymma UL

Doctoral thesis (2014)

Elastomers are key-materials e.g. in tire industry. Nowadays it is common practice to enhance the mechanical performance of elastomers by introducing inorganic nanoparticles into the polymer matrix. Due ... [more ▼]

Elastomers are key-materials e.g. in tire industry. Nowadays it is common practice to enhance the mechanical performance of elastomers by introducing inorganic nanoparticles into the polymer matrix. Due to the extremely small filler size giant interfaces are created between the surfaces of the nanoparticles and the matrix molecules especially when the fillers are homogeneously distributed throughout the host material. Interfacial interactions can lead to the formation of regions with changed molecular mobility and/or morphology (so-called interphases) in the immediate vicinity of the fillers’ surfaces. A challenging task consists in investigating and understanding the effect produced by interphases on the macroscopic properties of the polymer matrix. In the frame of the present PhD research project an uncured styrene-butadiene rubber (SBR) was used as a matrix for three types of nanoparticles: native alumina, alumina coated with γ- mercaptopropyltrimethoxysilane (Mercapto) layers and finally alumina-Mercapto nanoparticles with SBR molecules grafted onto. The thermal and mechanical properties of the three families of nanocomposites were investigated using mechanical spectroscopy (rheometry and dynamical mechanic analysis). Electron microscopy was exploited for structural analysis. Irrespective of the surface treatment of the nanoparticles an unexpected minimum of the glass transition temperature is found at small filler concentrations of about 2 wt.%. At higher filler contents each of the three families of nanocomposites is characterized by its own characteristic evolution of the glass transition temperature as a function of the filler content. Models are suggested to explain the different glass transition behaviors. Furthermore the influence of the surface treatment on the mechanical answer of the nanocomposites especially to low-frequency shear fields is discussed. [less ▲]

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See detailThe scientific journal in the age of digital multimodality
Blanca, Philippe UL

Doctoral thesis (2014)

Detailed reference viewed: 80 (6 UL)
See detailOptimal rates, Fourth Moment Theorems and non-linear functionals of Brownian local times
Campese, Simon UL

Doctoral thesis (2014)

The present dissertation provides contributions to three distinct topics of modern stochastic analysis, namely: (a) optimal rates of convergence in multidimensional central limit theorems (CLTs) on a ... [more ▼]

The present dissertation provides contributions to three distinct topics of modern stochastic analysis, namely: (a) optimal rates of convergence in multidimensional central limit theorems (CLTs) on a Gaussian space, (b) Fourth Moment Theorems (and associated multidimensional generalisations) in the framework of the chaos of a Markov generator and (c) CLTs for non-linear functionals of Brownian local times. [less ▲]

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See detailRegulation of neutrophil cytokine release and degranulation during inflammation: Role of SNARE fusion proteins
Naegelen, Isabelle UL

Doctoral thesis (2014)

Neutrophil granulocytes are the first effector cells to be recruited to sites of infection. They rapidly release granule proteins and pro-inflammatory cytokines to efficiently kill intruding pathogens and ... [more ▼]

Neutrophil granulocytes are the first effector cells to be recruited to sites of infection. They rapidly release granule proteins and pro-inflammatory cytokines to efficiently kill intruding pathogens and recruit other immune cells. In exocytotic events, specific interactions of so-called soluble N-ethylmaleimide-sensitive-factor attachment receptor (SNARE) proteins lead to the formation of complexes in order to mediate membrane fusion. Because of the excessive release of neutrophil-derived mediators leading to the development of chronic inflammatory disorders, we aimed in the present scientific work to investigate in more details the regulatory processes of mediator release in neutrophils during inflammation, with emphasis on SNARE proteins. The main objectives were i) to characterize the release of pro-inflammatory mediators, ii) to profile SNARE expression, iii) to determine the functional role of SNAREs and SNARE complexes in cytokine release and degranulation, and iv) to identify the intracellular localization of SNAREs. To characterize the pro-inflammatory response in neutrophils in regard to exocytosis, extensive kinetic studies were performed in a first step on LPS-stimulated primary neutrophils. A novel linear fitting approach was created to correlate the relationship between granule proteins and cytokines secreted to the inflammatory site. In a second step, SNARE expression levels were determined by whole-transcript analysis and the similar profiles in primary neutrophils as well as DMSO-differentiated HL-60 cells (dHL-60 cells), a neutrophil cell model, were underlined. Using an RNAi strategy, the SNARE syntaxin 3 (STX3) was identified as an essential actor in the release of the cytokines IL-1α, IL-1β, IL-12b, and CCL4. It was also involved in MMP-9 exocytosis from gelatinase granules where it could partly be localized. The SNARE SNAP29, which shares common localization with STX3, functionally affects the release of IL-12b, CCL2 and IL-8 as well as MMP-9, and represents a potential candidate to form cognate complexes with STX3. The knockdown of VAMP3, another SNARE candidate, showed deregulated secretion of IL-12b, CCL4, IL-8 as well as MMP-9. However, VAMP3 was located at the plasma membrane and was thus excluded as being part of the STX3-SNAP29 complex. Our findings provide first evidence that SNARE fusion proteins are involved in the release of IL- 12b, IL-1α, IL-1β, CCL4, IL-8, and CCL2 in a neutrophil-like cell model. The impact of SNAREs on gelatinase degranulation led us to hypothesize that cytokines might be packaged in these granules before subsequent exocytosis. ! [less ▲]

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See detail(Z_2)^n-Superalgebra and (Z_2)^n-Supergeometry
Covolo, Tiffany UL

Doctoral thesis (2014)

The present thesis deals with a development of linear algebra, geometry and analysis based on (Z_2)^n-superalgebras: associative unital algebras which are (Z_2)^n-graded (for some natural number n) and ... [more ▼]

The present thesis deals with a development of linear algebra, geometry and analysis based on (Z_2)^n-superalgebras: associative unital algebras which are (Z_2)^n-graded (for some natural number n) and graded-commutative, i.e., satisfying ab = (-1)^<deg(a),deg(b)> ba, for all homogeneous elements a, b of respective degrees deg(a), deg(b) in (Z_2)^n, and < . , . > denoting the usual scalar product. This generalization widens the range of applications of supergeometry to many mathematical structures -- the algebra of quaternions H and more generally Clifford algebras, Deligne algebra of superdifferential forms, higher vector bundles ... -- and appears also in physics -- for describing anyons, paraparticles -- proving its worth and relevance. In this dissertation, we first focus on (Z_2)^n-superalgebra theory: we define and characterize the notions of trace, determinant and Berezinian of matrices over graded-commutative algebras. Special attention is given to the case of Clifford algebras, where our study gives a new approach to treat the classical problem of finding a “good” determinant for matrices with non-commuting (quaternionic) entries. Further, we undertake the study of (Z_2)^n-graded differenital geometry. Privileging the ringed space approach, we define (smooth) (Z_2)^n-supermanifolds modeling their algebras of functions on the (Z_2)^n-commutative algebra of formal power series in graded variables, and develop the theory along the lines of supergeometry. Notable results are: the graded Berezinian and its cohomological interpretation (essential to establish integration theory); the theorem of morphism, which states that a morphism of (Z_2)^n-supermanifolds can be recovered from its coordinate expression; an analogous of Batchelor-Gawedzki theorem for (Z_2)^n-supermanifolds. [less ▲]

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See detailASSESSMENT OF PSYCHOLOGICAL AND PSYCHOPHYSIOLOGICAL CHARACTERISTICS INVOLVED IN THE MODULATION OF ENDOGENOUS PAIN CONTROL PATHWAYS AND IN THE INDUCTION OF PARADOXICAL PAIN
Scheuren, Raymonde UL

Doctoral thesis (2014)

The present doctoral thesis involves three experimental studies on pain processing and its modulation by psychological mechanisms. The first investigation focused on the relationship between associative ... [more ▼]

The present doctoral thesis involves three experimental studies on pain processing and its modulation by psychological mechanisms. The first investigation focused on the relationship between associative learning aspects and the endogenous pain control system referred to as diffuse noxious inhibitory controls (DNIC) or conditioned pain modulation (CPM). The aim of the study consisted in uncovering whether descending pain inhibition may depend on specific environmental or circumstantial cues that have been linked to a reduction of pain sensations through associative learning in pain treatment contexts. A heterotopic noxious counter-stimulation (HNCS) was used to trigger the endogenous pain control system in the experimental context. For the study of the potential impact of associative learning on the pain-inhibits-pain phenomenon, a respondent (Pavlovian) conditioning procedure was realized during the HNCS stimulation. It could be shown that the repeated pairing of a phone signal (conditioned stimulus, CS) with the unconditioned tonic pain stimulus (UCS, HNCS) enabled the CS in the post-conditioning phase to generate a DNIC-like effect similar to the one induced by the tonic pain stimulus. The results demonstrated that learning processes are able to influence endogenous pain modulation processes and decreases in pain perceptions and reflex activity. A thermal grill paradigm was used in the second and third study to examine the influence of psychological characteristics on the individual disposition to display the thermal grill illusion (TGI) of pain. First, the impact of pain-related personality traits like trait anxiety, pain catastrophizing, rumination, pessimism, expectancy of pain, suggestibility and interoceptive accuracy on inter-individual differences in paradoxical pain sensitivity was assessed. Second, the potential influence of dispositional self-regulation ability on illusive pain perceptions was measured. Vagally mediated heart rate variability (HRV) at rest was used as an index of individual self-regulatory strength. The results allowed identifying several psychological factors that are substantially affecting thermal grill-related perceptions. Mainly ruminative and interoceptive accuracy features increased the probability of paradoxical pain perceptions. The likelihood of the TGI elicitation was in addition significantly affected by the magnitude of the HRV-indicator respiratory sinus arrhythmia (RSA). Since thermal grill and neuropathic pain-related pain processing share common neural pathways, the identified psychological effects may be relevant in the context of pathological pain conditions. [less ▲]

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See detailGeographical Determinants of Residential Land Values in Luxembourg
Caruso, Geoffrey UL

Doctoral thesis (2014)

The sustained periurbanisation observed throughout Luxembourg has considerably challenged spatial planning policies. The limited success of recent policies that aimed at modifying consumers’ residential ... [more ▼]

The sustained periurbanisation observed throughout Luxembourg has considerably challenged spatial planning policies. The limited success of recent policies that aimed at modifying consumers’ residential preferences, underlies the main research objective of this thesis to further understand consumers’ preferences for the local geographical context, that can be considered as additional drivers of the ongoing urban spatial expansion. Besides the standard trade-off discussed in the monocentric city model (Alonso, 1964), several extensions to this model and specifically the periurban model (Cavailhès et al., 2004) have shown the utility bearing attributes of local urban and rural amenities for land consumers. By the means of the hedonic pricing method (Rosen, 1974), I aimed thus at identifying the marginal value of periurban amenities developable land consumers revealed when purchasing land. The main question addressed in this thesis is how urban and green amenities are valued by land consumers in Luxembourg, relying on advanced spatial econometric techniques. Further the focus was turned to the heterogeneity of consumers’ preferences with regard to their socio-economic background, relying on the spatial quantile regression approach. Moreover, spatial market segmentation and spatial heterogeneity in the valuation of the geographical determinants was further investigated by relying on the multilevel modelling approach, rather an uncommon practice in hedonic modelling context. The results of the thesis confirm that distance to Luxembourg by car and parcel size are the main determinants of land prices in Luxembourg, confirming thus urban economic theory. It was shown that not all land consumers are in competition on the same market and spatial market segments have been identified. Further, we show that land-use diversity is valued differently at different distances and that its marginal impact varies throughout Luxembourg, depending on the specific geographical context, and with regard to the price distribution. Results underline the importance of periurban amenities in consumers’ location decision, that however vary between (spatial) market segments. Accounting for the specificities of the local geographical context and individuals needs should help finding ways to design more acceptable and liveable neighbourhood plans that at the same time account better for the negative effects of urban spatial expansion. [less ▲]

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See detailAn Empirical Study of Browsers' Evolution Impact on Security and Privacy
Abgrall, Erwan UL

Doctoral thesis (2014)

Web success is associated with the expansion of web interfaces in software. They have replaced many thick-clients and command-line interfaces. HTML is now a widely adopted generic user-interface ... [more ▼]

Web success is associated with the expansion of web interfaces in software. They have replaced many thick-clients and command-line interfaces. HTML is now a widely adopted generic user-interface description language. The cloud-computing trend set browsers in a central position, handling all our personal and professional information. Online banking and e-commerce are the sources of an attractive cash flow for online thefts, and all this personal information is sold on black markets. Unsurprisingly, web browsers are consequently the favorite targets of online attacks. The fierce competition between browser vendors is associated with a features race, leading to partial implementation of W3C norms, and non-standard features. It resulted in a fast release pace of new browser versions over these last years. While positively perceived by users, such competition can have a negative impact on browser security and user privacy. This increasing number of features and the discrepancies between browser vendors' implementations facilitate the attacker task for cross site scripting(XSS) and drive-by download attacks. Coming to the overall objectives of a research leading to the better understandings of browser's role in security, this thesis provides an instrument to understand XSS attack vectors, categorize them, evaluate the exposure of web browsers against XSS and may eventually open the field, but this is beyond the scope of this thesis, to a new strategy to detect future client-side attacks, however this last point is beyond the scope of this thesis. [less ▲]

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See detailMulticulturalism within the Luxembourg context
Murdock, Elke UL

Doctoral thesis (2014)

Even within a globalizing world, Luxembourg takes an exceptional position with a foreign population of 44%, rising to 68% in the capital, home to a fifth of the country’s population. Luxembourg, and in ... [more ▼]

Even within a globalizing world, Luxembourg takes an exceptional position with a foreign population of 44%, rising to 68% in the capital, home to a fifth of the country’s population. Luxembourg, and in particular its capital, therefore form a “natural laboratory” to examine how an increasingly diverse society is perceived by the majority population who finds itself in the minority. Different facets of multiculturalism were examined in a series of quantitative studies. The first study examined the salience of nationality in the spontaneous self-concept as a function of context. The study found that students in a nationally heterogeneous environment mentioned nationality more frequently in their spontaneous self-concept than those in a nationally homogeneous context. Bringing people of different nationalities together does not diminish awareness of nationalities; on the contrary, salience of nationality is increased, as explained by the distinctiveness paradigm. Within a multicultural society, identification in terms of nationality is therefore more likely. The link between multilingualism and biculturalism was examined in the second study. Luxembourg is not only multicultural in terms of its demographic composition, but multilingual as a country with three officially recognized languages. This study confirmed that Luxembourg participants self-identified as multilingual, but the majority also as monocultural, therefore defying the assumption that bilinguals tend to be bicultural. Language competence was identified as a necessary, but not sufficient condition for biculturalism. Luxembourg participants differed in terms of internalization of language and culture. Those who experienced language as a cultural prime were more likely to self-identify as bicultural. Biculturals in turn reported less conscious effort in switching between cultures. A third study examined how biculturals organize and experience their dual nationalities. The study showed that adolescents growing up in mixed national familie are more likely to self-identify in a bicultural way. They experienced their dual nationalities as complementary and as a source of self-enhancement and pride rather than conflict. These findings were explained within the Acculturation Complexity Framework (ACM). Individuals who feel accountable to a mixed audience, may, after a period of dissonance, develop integrative complexity and a bicultural orientation. In the ACM model, the trigger for the increased cultural attention scope is second culture exposure. The opportunity for second culture exposure is increased in a multicultural society. A final series of studies assessed the attitude towards multiculturalism, defined as the attitude towards the plurally composed society. An empirical study was conducted within a large Luxembourg employer with a predominantly native born workforce. The endorsement of multiculturalism was measured using established multiculturalism scales. The influence of various factors such as demographic variables, inter-group relations variables, language use and individual difference variables such as the human values as measured by the Schwartz Values Structure and the understanding of nationality and their relationship with multiculturalism was examined. The results show a widespread endorsement of the idea of multiculturalism, in the sense of broadening and enriching of horizons. The acceptance of behavioural aspects of living together (i.e. societal participation) is yet to be aligned. Those in favor of multiculturalism focus mainly on intangible aspects whereas more critical voices concentrate on the tangible aspects of living together. Taken all this together, the current studies highlighted the role of language as well as culture contact for the construction of mono- or bicultural identity. Findings did not show however a simple linear relation between these variables but underlined the importance of third-variables moderating or mediating these relationship. This differential result pattern will set the frame for future studies. [less ▲]

Detailed reference viewed: 299 (43 UL)
See detailThe Limits of the European Union’s Transformative Power: Pathologies of Europeanization and Rule of Law Reform in Central and Eastern Europe
Mendelski, Martin UL

Doctoral thesis (2014)

This thesis examines the impact of the European Union (EU) on the development of the rule of law in Central and Eastern Europe. The topic is addressed through a mixed methods study which consists of a ... [more ▼]

This thesis examines the impact of the European Union (EU) on the development of the rule of law in Central and Eastern Europe. The topic is addressed through a mixed methods study which consists of a quantitative comparative analysis of three country groups from Central and Eastern Europe (1. Central Europe and the Baltics, CEB; 2. South Eastern Europe, SEE; 3. Commonwealth of Independent States, CIS) and three qualitative case studies on Poland, Romania and Moldova. The empirical analysis is based on an innovative set of indicators and revealing insights from numerous qualitative interviews. The findings of the study suggest that the impact of the EU is differential, both healthy and pathological. While EU-driven judicial reforms increase judicial capacity and align domestic legislation with European and international standards (substantive legality), they do not improve and even lead to a deterioration of judicial impartiality and formal legality, resulting in several reform pathologies, such as instable, incoherent and non-enforced laws and in more politicized and incoherent judicial systems, which undermine the development of the rule of law. These pathological effects occur mostly in weak rule of law countries from SEE (Romania) and CIS (Moldova), in contrast to more healthy effects in advanced, strong rule of law countries from CEB (Poland). The dissimilar development in the rule of law across countries is explained in relation to the conduct of reforms. Successful reformers like Poland, which consolidate the rule of law, have strong and independent horizontal accountability institutions (e.g. Constitutional Court, Ombudsman, judiciary), which mitigate or alleviate reform pathologies and ensure that reforms are conducted in an accountable, gradual and non-politicized way. Unsuccessful reformers, like Romania and Moldova, lack these independent checks on reformers and thus fail to establish the rule of law. Based on the findings from the case studies an original typology of healthy and pathological reform paths is proposed, which draws on the logic of circular and cumulative causation and emphasizes the mutual reinforcement between domestic conditions and the reform approach of transnational coalitions. The proposed typology implies that EU conditionality is not transformative, but rather reinforces existing healthy and pathological reform paths, thus cementing the existing divergence in the rule of law across post-communist countries. This thesis further makes several policy recommendations to remedy the pathological impact of donor-driven reforms. [less ▲]

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See detailVAT neutrality
Herbain, Charlene Adline UL

Doctoral thesis (2014)

Most major economies use a value added tax (VAT) which is a derivation of the French 1954 taxe sur la valeur ajoutée. The initial imposition of VAT in France and its spread around the world have been ... [more ▼]

Most major economies use a value added tax (VAT) which is a derivation of the French 1954 taxe sur la valeur ajoutée. The initial imposition of VAT in France and its spread around the world have been driven by economic reasons. This thesis focuses on one of these economic triggers: the neutrality of VAT as regards the functioning of the economy. It demonstrates that the reason VAT was chosen in France and why thereafter it spread around the world was because it offered the possibility to collect governmental revenue while allowing the economic forces of the market to interplay without being adversely affected. The prerequisite conditions for the existence of VAT neutrality are therefore identified herein along with an overview of the VAT mechanism, demonstrating that the concept of neutrality is built into the VAT system in a manner that allows for the preservation of the natural functioning of the market. After the definition of VAT neutrality is set forth, the elements that comprise VAT neutrality are tested against the realities on the ground and the issues that infringe the neutrality of VAT are identified and analysed. In conclusion, remedies for these issues are being sought by a review of the causes of infringement of VAT neutrality in the perspective of selected proposals for modified VAT systems. These proposals include redesignating the place where VAT is levied and improving VAT collection. Ultimately, the proposed solution has recourse to the roots of VAT together with the most advanced technological tools available to give back to VAT the power to levy revenue while letting the economic forces of the market interplay without instigating any adverse influence. [less ▲]

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See detailMolecular role of TRIM32 in stem cell fate specification
Nicklas, Sarah UL

Doctoral thesis (2014)

Stem cells have the ability to either self-renew, thereby maintaining their stem cell status, or to undergo differentiation. The balance between stem cell maintenance and differentiation is tightly ... [more ▼]

Stem cells have the ability to either self-renew, thereby maintaining their stem cell status, or to undergo differentiation. The balance between stem cell maintenance and differentiation is tightly regulated by a complex interplay of various signaling pathways, cell fate determinants and non-coding RNAs, including microRNAs (miRNAs). One important cell fate determinant during embryonic and adult neurogenesis is the TRIM-NHL family member TRIM32. In neural stem cells (NSCs), TRIM32 inhibits proliferation and induces neuronal differentiation by two mechanisms. On the one hand, TRIM32 ubiquitinates the transcription factor c-Myc, thereby targeting it for proteasomal degradation and inducing cell-cycle exit. On the other hand, TRIM32 associates with the RNA-induced silencing complex (RISC) and increases the activity of certain miRNAs such as Let-7a. However, the exact mechanism of miRNA regulation by TRIM32 during neuronal differentiation remains elusive. Here, we used a mass spectrometry approach to identify novel protein-protein interaction networks centred on TRIM32 during neuronal differentiation. By applying bioinformatic tools, we identified an enrichment of proteins involved in neurogenesis and RNA-related processes among the TRIM32-associated proteins. One of the candidates discovered in this screen was the RNA helicase DDX6, which has been implicated in miRNA regulation. Here, we demonstrate, that DDX6 colocalises with TRIM32 in NSCs and neurons and that it increases the activity of Let-7a. Furthermore, we provide evidence that DDX6 is necessary and sufficient for neuronal differentiation and that it functions in cooperation with TRIM32. Similar to TRIM32, the Parkinson’s disease (PD)-associated leucine-rich repeat kinase 2 (LRRK2) protein plays crucial roles in adult neurogenesis and miRNA regulation. LRRK2 is expressed in the stem cell niches of the embryonic and adult mouse brain. Moreover, neurogenesis is impaired in mice carrying the PD-associated LRRK2(G2019S) mutation, suggesting that LRRK2 plays an important role in neurogenesis. However, the precise role of LRRK2 in neuronal differentiation and neurogenesis is poorly understood. Previously, LRRK2 has been shown to associate with RISC, thereby repressing the activity of miRNAs such as Let-7a, and this repression was further enhanced by the G2019S mutation. We addressed the role of LRRK2 in miRNA-mediated neuronal differentiation by using NSCs derived from mice carrying the PD-associated LRRK2(R1441G) mutation as well as from LRRK2 knock-out mice. Here, we demonstrate that LRRK2(R1441G) NSCs display increased levels of oxidative stress and are more susceptible to cell death upon neuronal differentiation. Consequently, neuronal differentiation is greatly impaired, while NSC self-renewal is unaffected in these cells. In contrast, LRRK2 deficiency in NSCs produced the opposite effect on oxidative stress, cell survival and neuronal differentiation. Interestingly, the expression levels of the miRNAs Let-7a and miR-9 were downregulated in LRRK2(R1441G) NSCs, possibly accounting for the observed neuronal differentiation defect in these cells. These data indicate that LRRK2 regulates miRNAs to modulate neuronal differentiation with opposing effects compared to TRIM32. Thus, LRRK2 may antagonize the function of TRIM32 in miRNA-mediated neuronal differentiation. Besides its role in the brain, TRIM32 also plays an important role in skeletal muscle, as it is implicated in the aetiology of Limb girdle muscular dystrophy type 2H (LGMD2H). LGMD2H is an inherited autosomal recessive disease of skeletal muscle caused by a mutation in the TRIM32 gene. Despite several studies addressing the function of TRIM32 in skeletal muscle, the contribution of TRIM32 to the pathogenesis of LGMD2H is poorly understood. Typically the regeneration process of adult skeletal muscle during growth or following injury is controlled by a tissue specific stem cell population termed satellite cells. Given that TRIM32 regulates the fate of mammalian NSCs by controlling their differentiation, we hypothesized that TRIM32 could also be essential for the regulation of satellite cells. Here we demonstrate for the first time that TRIM32 is expressed in the skeletal muscle stem cell lineage of adult mice and that it is strongly induced during muscle differentiation in vitro and during muscular regeneration in vivo. We show that TRIM32 is necessary and sufficient for myoblast differentiation in muscle progenitor cells, a function that is dependent on the ubiquitination and degradation of its binding partner c-Myc. Finally, we demonstrate that loss of TRIM32 in mice strongly impairs skeletal muscle regeneration in vivo similar to LGMD2H patients. Our studies indicate that loss of TRIM32 results in dysfunctional muscle stem cells, which could contribute to the development of LGMD2H. Overall, this work provides important insights into the mechanisms, by which TRIM32 regulates the balance between stem cell maintenance and differentiation in the adult brain and skeletal muscle. [less ▲]

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See detailSecurity Analysis of Permission-Based Systems using Static Analysis: An Application to the Android Stack
Bartel, Alexandre UL

Doctoral thesis (2014)

In recent years, mobile devices, such as smart phones, have spread at an exponential rate. The most used system running on these devices, accounting for almost 80% of market share for smart phones world ... [more ▼]

In recent years, mobile devices, such as smart phones, have spread at an exponential rate. The most used system running on these devices, accounting for almost 80% of market share for smart phones world-wide, is the Android software stack. This system runs Android applications that users download from an application market. The system is called a permission-based system since it limits access to protected resources by checking that applications have the required permission(s). Users store and manipulate personal information such as contact lists or pictures using applications on their devices and trust that their data is safe. Analyzing applications and the system on top of which they are running would be an objective method to evaluate if the data is well-protected.In this thesis we aim at analyzing Android applications from the security point of view and answering to the following challenging questions: How can Android applications be analyzed? Are permissions well-defined for Android applications? Can applications leak protected data? How can dynamic analysis complement static analysis? To answer these questions we structure the thesis around four objectives. The first objective is to analyze Android applications with static analysis tools. The challenge is that Android applications are packaged with Dalvik bytecode, different in many aspects from the Java bytecode. We developed Dexpler, a tool to transform Dalvik bytecode into Jimple, an understandable format for Soot, one of the most used static analysis framework for Java-based programs. With Dexpler we can now analyze Android applications.The second objective is to check that developers do not give too many permissions to the Android applications they develop. Reducing the number of permission reduces the attack surface of an malicious user exploiting an application. We analyze the code of applications to check which permissions they really require. This requires to deeply analyze the Android framework to extract a mapping between API methods (that Android application call) and required permissions. We present an Andersen-like field-sensitive approach using novel domain-specific optimizations to extract the mapping from the Android framework. Permissions protect sensitive data. Nevertheless, applications having the right permission(s) to access the data could leak the data. This is for instance the case with malware or application packaged with aggressive advertisement libraries. The third objective is to statically analyze Android applications to detect such leaks. Android applications are different from traditional Java applications. One of the most important differences is that Android applications are made of components. Analyzing Android applications to find leaks requires to link components that communicate together and to model every component. We developed IccTA to detect privacy leaks. It connects components at the code level to perform inter-component and inter-application data-flow analysis.Analyzing Android applications statically enables to find security issues such as the GPS coordinates leaking out of the device. However, static analyses do not run directly on users’ devices and thus do not take the device’s context into account. The last objective of this thesis is to have an insight of how dynamic approaches can complement static analyses. We are the first to present a tool-chain to dynamically instrument Android applications in vivo, i.e. directly on the device. We present two use cases instrumenting applications to show that dynamic approaches are feasible, that they can leverage results from static analyses, and that they are beneficial for the user from the point of view of security or privacy. One of the use case is a fine-grained permission system prototype enabling the user to disable or enable application permissions at will. The four contributions have been validated through rigorous experiments as complete as possible. Through this thesis we provide solutions to analyze Android applications using static analysis, to check the permission set of applications, to find private data leaks in Android applications and to analyze permission-based frameworks. By analyzing what goes wrong, we can improve the security and privacy of mobile applications. [less ▲]

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See detailENERGY-EFFICIENT SCHEDULING IN GRID COMPUTING AND RESOURCE ALLOCATION IN OPPORTUNISTIC CLOUD COMPUTING: MODELS AND ALGORITHMS
Diaz, Cesar UL

Doctoral thesis (2014)

Resource allocation among Heterogenous Computing Systems (HCS) components, such as cluster, grid, or cloud computing can be considered as a service. These systems manage millions of computational ... [more ▼]

Resource allocation among Heterogenous Computing Systems (HCS) components, such as cluster, grid, or cloud computing can be considered as a service. These systems manage millions of computational resources to solve several difficult com- putational problems. Resource allocation and scheduling among these systems are still a hot topic for research purposes. A goal of this research is to find an effi- cient use of these resources proposing a resource allocation and efficient scheduling techniques. Firstly, the relevance of energy consumption in processing elements as well as techniques and policies to support it are presented. It emphasizes in resource allocation algorithms in opportunistic environments and low complexity scheduling heuristics in grid computing environment. In particular, a series of low complexity, scalable, and energy-efficient algorithms for scheduling in grid computing and a resource allocation technique for opportunistic environment are presented. The latest aforementioned technique was evaluated in an opportunistic cloud environment. Three fast and energy-efficient batch mode scheduling novel heuristics were designed, developed, and evaluated to produce fast tasks mapping in HCS. To fully understand their capabilities and limitations, these aforemen- tioned heuristics were studied and compared with a variety of system parameters for their performance and scalability. [less ▲]

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See detailQuantifications par déformations formelles et non formelles de la boule unité de C^n
Korvers, Stéphane UL

Doctoral thesis (2014)

À la frontière de domaines de recherche tels que la géométrie différentielle, l’analyse harmonique sur les espaces homogènes, les équations aux dérivées partielles ou la théorie des fonctions spéciales en ... [more ▼]

À la frontière de domaines de recherche tels que la géométrie différentielle, l’analyse harmonique sur les espaces homogènes, les équations aux dérivées partielles ou la théorie des fonctions spéciales en physique mathématique, cet ouvrage propose au lecteur de découvrir la quantification par déformation des domaines bornés homogènes complexes sous un nouveau jour. Une étude géométrique des nombreuses facettes de la boule unité de l’espace de n variables complexes comme brique élémentaire de ces domaines précède l’exposé des recherches menées par l’auteur dans le cadre de sa thèse de doctorat. Celles-ci visent notamment la réalisation explicite de l’ensemble des quantifications par déformations sur cette variété. À ces fins, il est montré qu’une telle réalisation se ramène à une hiérarchie d’équations aux dérivées partielles explicite dont certaines solutions définissent des opérateurs de convolution entrelaçant la théorie des déformations au niveau de la boule unité avec celle d’une contraction de courbure de cet espace. La résolution de ces équations est discutée sous plusieurs angles, laissant entrevoir de multiples perspectives à ce travail. [less ▲]

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See detailDetection and characterization of critical transitions in mitochondrial activity via high content screening
Trefois, Christophe UL

Doctoral thesis (2014)

Critical transitions exist in many dynamical systems, ranging from the Earth’s cli- mate system to microcosm populations. During a critical transition, the state of a dynamical system abruptly changes ... [more ▼]

Critical transitions exist in many dynamical systems, ranging from the Earth’s cli- mate system to microcosm populations. During a critical transition, the state of a dynamical system abruptly changes from one stable state to another, typically without obvious prior warning. Preventing such abrupt changes remains a chal- lenge, however recently, several metrics were suggested as early warning signals. These indicators are thought to have predictive value for upcoming critical transi- tions. In Parkinson’s disease, there are no detectable motor symptoms in a patient until neuronal dopaminergic cell death exceeds 60–70%. Being able to define early warning signals in a disease context could open new avenues for both preventive and disease modifying treatments. We hypothesize that the dynamics of progression of some disorders including Parkinson’s disease could be manifested by critical tran- sitions. However, before rushing into medical applications, a thorough framework needs to be developed that aims to describe such nonlinear dynamics in cellular systems. In this thesis, we set out to study critical transitions in a simple cellular model using mitochondrial membrane potential ∆Ψ m as readout. To identify criti- cal transitions, we established a modular high-content screening platform allowing systematic perturbation of oxidative phosphorylation. To increase the probability for detecting a critical transition in ∆Ψ m , five inhibitory compounds were combined in multiple pairwise concentration landscapes. We show that critical transitions, de- tectable via ∆Ψ m , are an intrinsic property of the cellular system studied and that two-component Gaussian mixture models adequately capture the dynamics of the critical transition occurring for the combination of Oligomycin A and Antimycin A. Adding to that, we identified the coefficient of variation as a strong early warning signal for the upcoming of the critical transitions. This thesis should serve as a foundation for a broader application of critical transitions and early warning sig- nals in both cell culture systems and translational studies aiming to understand the nonlinear dynamics of biological systems. [less ▲]

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See detailNeutronenstreuuntersuchungen zur magnetischen Mikrostruktur Nd-Fe-B-basierter Nanokomposite
Bick, Jens-Peter UL

Doctoral thesis (2014)

Exchange-coupled magnetic nanocomposites are considered to be promising candidates for future permanent magnet applications. These nanocomposites consist of a hard magnetic phase (based on rare-earth ... [more ▼]

Exchange-coupled magnetic nanocomposites are considered to be promising candidates for future permanent magnet applications. These nanocomposites consist of a hard magnetic phase (based on rare-earth metal alloys), which provides high magnetic anisotropy and which is exchange coupled to a soft magnetic rare earth free phase, which provides a high saturation magnetization and Curie-temperatur. For suitable microstructures one could achieve on the one hand side dramatically increased energy products, in comparison to state-of-the-art Dy-Nd-Fe-B magnets. On the other hand side – due to the reduced amount of rare earth metals – expenses could be saved significantly. The understanding of the coercivity mechanisms in these materials is crucial for the development of nanocomposite permanent magnets. In the present work, the magnetization reversal of a two-phase Nd2Fe14B/Fe3B nanocomposite has been studied by means of magnetic small angle neutron scattering (SANS). This technique exclusively provides access to information of the magnetic microstructure in the bulk of the material and on the relevant length scales of 1 − 100 nm. Direct Fourier-transformation allowed the calculation of the correlation function of the spin misalignment C(r). From this data, the correlation length lc has been obtained. The parameter lc is a measure for the spatial extent of magnetization inhomogeneities. The field dependence of lc indicates a magnetization reversal process, which is widely governed by homogeneous rotation of the magnetization within the hard magnetic Nd2Fe14B particles. In addition, in terms of a micromagnetic approach, the exchange stiffness constant A was determined experimentally. [less ▲]

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See detailPropriétés optiques et volumiques en équilibre et hors-équilibre près de la transition de ségrégation de solutions aqueuses de PNIPAM par réfractométrie modulée en température
Aleksandrova, Ralitsa UL

Doctoral thesis (2014)

Self-assembly is particularly important for soft condensed matter. It may lead to manifold equilibrium or non-equilibrium structures and macroscopic properties of soft materials. The self-organization may ... [more ▼]

Self-assembly is particularly important for soft condensed matter. It may lead to manifold equilibrium or non-equilibrium structures and macroscopic properties of soft materials. The self-organization may be induced by changes in environmental conditions such as temperature, pH and irradiation by light. Among the different polymer families, the stimuli-responsive polymers are particularly sensitive to external stimuli. A structural instability, which is usually related to a demixing phase transition, commonly occurs for stimuli-responsive polymer systems. For such aqueous polymer solutions and hydrogels, a demixing transition of the Lower Critical Solution Temperature (LCST) type often happens, this means that the segregation occurs upon heating. Its macroscopic order parameter is attributed to the difference in mass concentration within the segregated state. Since the variation in mass density is a closely related quantity, the transition is also called a volume phase transition. In case of hydrogels, the order parameter also is the macroscopic deformation. In consequence the related susceptibility is the isothermal compressibility and the demixing transition is denoted as being ferroelastic. In this thesis, basic aspects of the static, kinetic and dynamical nature of the LCSTtype demixing transition are analyzed. Aqueous solutions of the thermo-responsive model homopolymer poly(N-isopropylacrylamide) (PNIPAM) are studied. Part of the phase diagram is probed by varying the polymer concentration in solution and the temperature. In part unconventional experimental techniques were used to access the macroscopic order parameter susceptibilities, like the dynamical volume expansion coefficient, and linear and nonlinear elastic properties at GHz frequencies. The major experimental technique is Temperature Modulated Optical Refractometry (TMOR), which has recently been developed in collaboration with the company Anton Paar (Seelze, Germany) and patented in 2012 by the University of Luxembourg. First studies by Brillouin spectroscopy were carried out on the segregation of aqueous PNIPAM solutions. The linear and in particular nonlinear elastic moduli are much more affected than the thermal expansion coefficient by this phase transition. Furthermore, it could be shown that the specific refractivity is astonishingly sensitive, probably to the changes in molecular interactions, during segregation. This allows for a novel perspective on the microscopic order parameters of the transition. The key investigations of this thesis focus on kinetics and thermo-mechanical relaxation processes related to the segregation, studying optical and mechanical quantities by TMOR. Sinusoidal temperature perturbations were therefore applied around the demixing temperature of different PNIPAM solutions. First direct indications for the location of the binodal and spinodal lines could be [less ▲]

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See detailUntersuchung der Ermüdungsfestigkeit von komplexen innendruckbelasteten Aluminiumgeometrien und der Lebensdauersteigerung durch Autofrettage
Sellen, Stephan UL

Doctoral thesis (2014)

Introducing gaseous high-pressure hydrogen storage for fuel cell vehicles requires safe light-weight valves for the automotive gas management. In contrast to thin-walled pressure vessels, there are no ... [more ▼]

Introducing gaseous high-pressure hydrogen storage for fuel cell vehicles requires safe light-weight valves for the automotive gas management. In contrast to thin-walled pressure vessels, there are no calculation or design guidelines available due to the huge variety of possible geometries and integrated functions. However, hydraulic cyclic pressure tests are compulsory for a finite-life fatigue strength certification of hydrogen valves. The valve body, linking different functional devices with each other via internal bore intersections, is the most critical part since the sharp-edged bore crossings cause high stress concentrations which distinctively limit the fatigue strength of such internally pressurized parts. Due to demands for light-weight design and manufacturing advantages it is aluminium which should be used as an appropriate material for the valve body. However, its fatigue properties need to be proved. Because of the complex valve body geometry, local fatigue evaluation concepts are initially applied to a simplified internally pressurized bore intersection and compared to the results of tested samples under pulsating pressure. However, those tests revealed an early crack initiation and a fast spreading of cracks in the aluminium under cyclic load and, thus, the requirements of the applicable testing regulation are not fulfilled. The present work focuses further on a method to increase the fatigue life by inducing residual compressive stresses at the areas of high stress concentrations. Here, the so called autofrettage, which is typically used for internally pressurized geometries, is a promising technology since it induces residual compressive stresses at the hotspots due to a unique static overload pressure with a distinctively higher pressure level than the subsequent cyclic pressure during operation. Although this is a well-known method, its potential for aluminium is not understood sufficiently. This is also the cast for the geometry dependent choice of a suitable autofrettage pressure range which is still inadequately clarified for the herein studied complex valve body geometry. An efficient design method based on a non-linear finite element method is derived from and applied to the valve body geometry. In order to perform the non-linear simulations, additional information about the plastification behaviour for reverse loading is necessary and being derived from uniaxial material tests. Fatigue testing of the valve body under cyclic pressure load shows a highly increased fatigue life and a design rule for the choice of an appropriate autofrettage pressure is verified. Besides sharp-edged bore intersections, high stress concentrations are also existent at the threads in the aluminium valve body, leading to an early crack initiation and a fast crack growth. In contrast to the typical implementation of the autofrettage process, it is shown that also even a unique static overload on the threads leads to an increased fatigue life. Thus, the end plugs should be used during the autofrettage process which causes residual compressive stresses at the thread root and a stress homogenisation over the carrying threads. These effects are studied with the help of non-linear finite element simulations considering the detailed thread geometry, the non-linear material behaviour and frictional contact. This leads to the conclusion that the effects of autofrettage as a method to increase the fatigue life by inducing residual compressive stresses for valve bodies for high-pressure hydrogen applications are being analysed in detail. As a result, it can be stated that with an appropriate selection of the autofrettage pressure and the suitable implementation of the process towards the valve body geometry, the required number of pressure cycles according to the applicable regulation can be successfully achieved. [less ▲]

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See detailEnergy-Performance Optimization for the Cloud
Pinel, Frédéric UL

Doctoral thesis (2014)

Detailed reference viewed: 141 (15 UL)
See detailThe Struggle in Online Copyright Enforcement - Problems and Prospects
Schmitz, Sandra Verena Ingrid UL

Doctoral thesis (2014)

The thesis analyses legal measures that aim at fighting and reducing copyright infringements on the Internet. The analysis focusses on approaches from France, UK and Germany in order to determine the most ... [more ▼]

The thesis analyses legal measures that aim at fighting and reducing copyright infringements on the Internet. The analysis focusses on approaches from France, UK and Germany in order to determine the most appropriate and effective road to take. [less ▲]

Detailed reference viewed: 206 (22 UL)
See detailOptimisation of Terahertz Photomixer Layout
Juul, Lars UL

Doctoral thesis (2014)

This thesis examines ways to improve the output power of LT GaAs terahertz photomixer circuits, by focusing on the large impedance mismatch between photoconductor and antenna which gives rise to loss of a ... [more ▼]

This thesis examines ways to improve the output power of LT GaAs terahertz photomixer circuits, by focusing on the large impedance mismatch between photoconductor and antenna which gives rise to loss of a large fraction of power, which could potentially have been absorbed by the antenna. Impedance matching is a known problem in the microwave domain, and in this work such approaches were implemented in the terahertz domain and evaluated using a commercial numerical simulation tool with measured material properties. ?e aim was to provide cost effective design suggestions which are easily integrated into existing single layer technologies. Evaluation of high impedance antennas with integrated DC-blocking showed improvements ranging from 1.5 to 3 times the output power compared to the 3.0 µW reference case at 0.85 THz. A quarterwave transformer with an added shunt capacitance shows a 4 times improvement over the reference case. Adding a multilayer DC-block structure yields a 5 times improvement. Corrugated high impedance wire structures were evaluated for suitability in terms of radiative and transmission properties, in search for improved matching elements. Furthermore, a mechanically tunable resonant photomixer has been proposed, which yields significant improvement in output power over existing tunable broadband photomixers. Finally, a modulation scheme is proposed for binary ASK-modulation in the gigabit per second range of a terahertz photomixer, using an off the shelf 10 Gbps output driver. [less ▲]

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See detailMultibeam Joint Processing in Satellite Communications
Christopoulos, Dimitrios UL

Doctoral thesis (2014)

Cooperative Satellite Communications (SatComs) involve multi-antenna satellites enabled for the joint transmission and reception of signals. This joint processing of baseband signals is realized amongst ... [more ▼]

Cooperative Satellite Communications (SatComs) involve multi-antenna satellites enabled for the joint transmission and reception of signals. This joint processing of baseband signals is realized amongst the distinct but interconnected antennas. Advanced signal processing techniques –namely precoding and Multiuser Detection (MUD)– are herein examined in the multibeam satellite context. The aim of this thesis is to establish the prominence of such methods in the next generation of broadband satellite networks. To this end, two approaches are followed. On one hand, the performance of the well established and theoretically concrete MUD is analysed over the satellite environments. On the other, optimal signal processing designs are developed and evaluated for the forward link. In more detail, the present dissertation begins by introducing the topic of multibeam joint processing. Thus, the most significant practical constraints that hinder the application of advanced interference mitigation techniques in satellite networks are identified and discussed. Prior to presenting the contributions of this work, the multi-antenna joint processing problem is formulated using the generic Multiuser (MU) Multiple InputMultiple Output (MIMO) baseband signal model. This model is also extended to apply in the SatComs context. A detailed presentation of the related work, starting from a generic signal processing perspective and then focusing on the SatComs field, is then given. With this review, the main open research topics are identified. Following the comprehensive literature review, the first contribution of this work, is presented. This involves the performance evaluation of MUD in the Return Link (RL) of multiuser multibeam SatComs systems. Novel, analytical expressions are derived to describe the information theoretic channel capacity as well as the performance of practical receivers over realistic satellite channels. Based on the derived formulas, significant insights for the design of the RL of next generation cooperative satellite systems are provided. In the remaining of this thesis, the focus is set on the Forward Link (FL) of multibeam SatComs, where precoding, combined with aggressive frequency reuse configurations, are proposed to enhance the offered throughput. In this context, the alleviation of practical constraints imposed by the satellite channel is the main research challenge. Focusing on the rigid framing structure of the legacy SatCom standards, the fundamental frame-based precoding problem is examined. Based on the necessity to serve multiple users by a single transmission, the connection of the frame-based precoding and the fundamental signal processing problem of physical layer multigroup multicasting is established. In this framework and to account for the power limitations imposed by a dedicated High Power Amplifier (HPA) per transmit element, a novel solution for multigroup multicasting under Per Anntenna Constraints (PACs) is derived. Therefore, the gains offered by multigroup multicasting in frame-based systems are quantified over an accurate simulation setting. Finally, advanced multicast and interference aware scheduling algorithms are proposed to glean significant gains in the rich multiuser satellite environment. The thesis concludes with the main research findings and the identification of new research challenges, which will pave the way for the deployment of cooperative multibeam satellite systems. [less ▲]

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See detailDesign and Implementation of Lattice-Based Cryptography
Lepoint, Tancrède UL

Doctoral thesis (2014)

Today, lattice-based cryptography is a thriving scientific field. Its swift expansion is due, among others, to the attractiveness of fully homomorphic encryption and cryptographic multilinear maps ... [more ▼]

Today, lattice-based cryptography is a thriving scientific field. Its swift expansion is due, among others, to the attractiveness of fully homomorphic encryption and cryptographic multilinear maps. Lattice-based cryptography has also been recognized for its thrilling properties: a security that can be reduced to worst-case instances of problems over lattices, a quasi-optimal asymptotic efficiency and an alleged resistance to quantum computers. However, its practical use in real-world products leaves a lot to be desired. This thesis accomplishes a step towards this goal by narrowing the gap between theoretical research and practical implementation of recent public key cryptosystems. In this thesis, we design and implement a lattice-based digital signature, two fully homomorphic encryption schemes and cryptographic multilinear maps. Our highly efficient signature scheme, BLISS, opened the way to implementing lattice-based cryptography on constrained devices and remains as of today a promising primitive for post-quantum cryptography. Our fully homomorphic encryption schemes enjoy competitive homomorphic evaluations of nontrivial circuits. Finally, we describe the first implementation of cryptographic multilinear maps. Based on our implementation, a non interactive key exchange between more than three parties has been realized for the first time, and amounts to a few seconds per party. [less ▲]

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See detailA Discrete Approach to Describe the Kinematics between Snow and a Tire Tread
Michael, Mark UL

Doctoral thesis (2014)

The objective of this study is to develop a simulation technique that enables to describe the interactions between snow and a moving surface. The develop- ments of this study are focused on the ... [more ▼]

The objective of this study is to develop a simulation technique that enables to describe the interactions between snow and a moving surface. The develop- ments of this study are focused on the application of the interactions between a tire tread and a snow-covered road. Contrary to a continuum mechanics approach snow is considered to exist of discrete grains which are allowed to bond and collide with each other. There- fore, a discrete approach based on the extended Discrete Element Method is applied to the snow. Micro-mechanical models are developed to describe the deformational behaviour of snow. The micro-mechanical models describe the deformation and growth of the bonds between grains as well as the contact behaviour of snow grains on the grain-scale. Further, the age of a snow sample, the temperature and deformation rate applied are taken into account by the de- veloped models. The deformational behaviour of snow under brittle and ductile loading rates is validated with experimental data of common measurements in the field of snow mechanics. The simulation results successfully recapture the macro- and micro-scale deformation behaviour of snow and enable to identify the primary deformation mechanism in charge at the different loading rates, densities and temperatures. However, this approach allows treating individual snow grains during loading due to a rolling tire and predicting both position and orientation of grains. The micro-mechanical response of each snow grain in contact with the structure of the tire surface generates a global impact that defines the interaction forces be- tween the snow and the tire surface, which simultaneously indicate the strength of traction. In order to predict the elastic deformation of the tire surface the Finite Element Method is employed. A coupling method is developed between the discrete approach to characterise snow and the finite element description of the tire tread. The coupling method compensates quite naturally the shortages of both numerical methods. Further, a fast contact detection algorithm has been developed to spare valuable com- putation time. The coupling approach was successfully tested and validated with a small scale application but also with the large scale application of tire - soil interaction. The large-scale simulation results of tire - soil interactions showed to be accurate in comparison to similar traction measurements. Finally, the interaction of snow with rigid and deformable tread parts has been studied in accordance to friction measurements of the field of tire mechanics. The results show the ability of the simulation technique to describe the targeted interactions and give valuable insight into the underlying mechanisms. [less ▲]

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See detailThe Europeanisation of national foreign policy in non-EU Europe. The case of Serbia and Macedonia.
Marciacq, Florent UL

Doctoral thesis (2014)

With the gradual consolidation of European foreign policy structures and the intensification of multi-level interactions in that area, Europeanisation has become a pregnant reality for non-EU Europe in ... [more ▼]

With the gradual consolidation of European foreign policy structures and the intensification of multi-level interactions in that area, Europeanisation has become a pregnant reality for non-EU Europe in general and Serbia and Macedonia in particular. What Europeanisation is, what it entails and how it proceeds remain yet subject to controversies. This thesis is a contribution to the academic debate. It explores how the national foreign policy of Serbia and Macedonia has been transformed over years, and uses its empirical findings to reflect on the concept, the phenomenon and mechanisms of Europeanisation in non-EU Europe. The thesis adopts an inductive research strategy, combining in its empirical part descriptive and argumentative analyses. It successively identifies a series of changes in Serbia and Macedonia’s foreign policy, which can be attributed to Europeanisation, and examines the underlying structural, dispositional and intentional forces, as well as the factors facilitating and constraining the process. It scrutinises several aspects of Serbia and Macedonia’s foreign policy: convergence in multilateral diplomacy, organisational reforms, resolution of border disputes, inflexions of critical foreign policy positions (Serbia’s Kosovo issue and Macedonia’s naming issue) and harmonisation of national systems of arms export controls. Its findings question the predominant role usually attributed to the EU and the significance of its conditionality policy in the area. They also underline the international and inter-organisational dimension of Europeanisation. These findings suggest that Europeanisation is best conceptualised through governance approaches (as opposed to EU integration approaches), and that it is best defined as “the transformation of political systems based on national governance into systems constituted by actors operating through the prism of European governance”. Europeanisation, as a phenomenon, is found to entail more intersubjectivity, more nodality and more homogeneity across political systems. As a process, it is found to ensue simultaneously from mechanistic, contextual and organismic learning, i.e. respectively, from structural necessities, shared understandings and individual dissatisfaction, depending on specific conditions. These findings shed light on the contribution of Europeanisation to the (trans)formation Europe’s political order. [less ▲]

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See detailMulti-dimensional interjurisdictional competition and coordination
Han, Yutao UL

Doctoral thesis (2014)

The present dissertation aims to extend classical tax competition to a more general framework in which jurisdictions compete in both taxes and non-tax instruments. In this context, issues related to ... [more ▼]

The present dissertation aims to extend classical tax competition to a more general framework in which jurisdictions compete in both taxes and non-tax instruments. In this context, issues related to dynamic competition and tax coordination are investi- gated. Dynamic aspects of multi-dimensional competition. Under dynamic competition, firms choose their location dynamically in each period to maximize their respective profits. We develop a dynamic relocation rule of firms based on the home attachment prin- ciple. Applying this rule, dynamic competition in taxes and public services among unequally sized jurisdictions is investigated. We account for the widely recognized characteristic that small states are more flexible in their decision-making than larger economies. However, small countries may suffer from limited institutional capacity in the provision of public services. Consequently, small and large countries behave asym- metrically when they compete for internationally mobile capital. This heterogeneity is analyzed within a differential game framework. We demonstrate that in case of high capital mobility small economies may collapse economically if public services are inef- ficiently provided. When capital mobility is very low, a small state’s economy always expands despite its limited institutional capacity. Tax coordination aspects. When jurisdictions compete in taxes and infrastructure, the desirability of tax coordination is analyzed. The timing of the game is considered in two different ways, simultaneous and sequential games. Two tax coordination devices (a common tax rate and a minimum tax rate) are considered. We demonstrate that tax coordination does not necessarily generate the welfare effects often observed in pure tax competition literature. The reason is that the decision to coordinate on tax rate in- duces a carry-over effect on infrastructure expenditures. Moreover, we highlight that tax coordination is more likely to be detrimental when countries can compete simulta- neously in taxes and infrastructure, rather than sequentially.Then, we investigate whether partial tax coordination benefits the tax union (the in- siders) and/or the outsiders since tax coordination can be decided among a subset of countries that forms a tax union. The member states of the union coordinate tax poli- cies but still compete in infrastructure provision. In addition, the union as a whole competes in taxes and infrastructure with the rest of the world. We demonstrate that partial tax coordination can harm both union members and non-union members. This contrasts with the classical view that partial tax coordination is Pareto improving. Size effect on social welfare. Finally, we analyze how social welfare is impacted by in- creasing the size asymmetry of countries when they compete in taxes and infrastruc- ture. It appears that increasing size asymmetry does not necessarily exacerbate the inefficiency of tax competition. More precisely, if the degree of international openness is low (high), social welfare decreases (increases) with size asymmetry. [less ▲]

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See detailLocation Assurance and Privacy in Location-based Services
Chen, Xihui UL

Doctoral thesis (2014)

Due to the development of global navigation satellite systems (GNSS), people are able to obtain their precise locations in real time. This in turn leads to a wide range of location-based services (LBS ... [more ▼]

Due to the development of global navigation satellite systems (GNSS), people are able to obtain their precise locations in real time. This in turn leads to a wide range of location-based services (LBS), through which a user can acquire information customised to locations. However, the vulnerabilities of GNSS systems and the exposure of information such as locations and queries in LBS requests impose a strong need from users on security. In this thesis, we study two security requirements in LBSs: location assurance and privacy. Location assurance expresses users’ requirement for trustworthy locations in terms of correctness and precision while privacy addresses users’ concern about personal information leakage in LBSs. First, we present a trust framework to detect spoofing by evaluating the integrity of GNSS signals. The framework combines existing spoofing detection methods to generate an overall quantitative evaluation of the integrity of received signals. Based on this evaluation, users can determine the extent to which they can trust their locations. We implement a prototype based on our framework and develop a public service called location assurance certification. In this service, a trusted agent is introduced to issue certificates for users’ locations according to the integrity of their received signals. Second, we propose a general approach to protect users’ query privacy when the adversary has access to various contextual information. We present a probabilistic framework, in which we formally define the attacks to infer the issuers of LBS queries by exploring various contextual information. With this framework, we propose a series of query privacy metrics. These metrics not only measure query privacy from different perspectives but also enable users to express their requirements for query privacy flexibly and precisely. Our framework finally allows us to develop new mechanisms which provide protection for users’ query privacy satisfying their requirements. Third, we address location privacy. Many location privacy preserving methods (LPPM) have been proposed to protect users’ location privacy. A user will make use of them to break the link between his identity and his locations when requesting LBSs. We propose a new attack on location privacy based on the adversary’s observation on users’ locations protected by LPPMs. Compared to existing attacks which target at where users went, our attack provides the adversary with sufficient information to infer what users did, i.e., their activities. Specifically, through our attack, the adversary learns the places where users performed activities and their beginning and ending time of each activity. To achieve this goal, we explore the patterns of users with respect to movements and requesting LBSs, i.e., user profiles. [less ▲]

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See detailAddressing 'abuse' in Luxembourg's tax law with a new GAAR
Köszeghy, Katarina UL

Doctoral thesis (2014)

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See detailNetwork-Enabled Capability: Modelling and Measurements
Goergen, David UL

Doctoral thesis (2014)

In public safety many actors work together to achieve a common goal. However, communication among these actors is not always possible. Most use their own communication system and infrastructure, which are ... [more ▼]

In public safety many actors work together to achieve a common goal. However, communication among these actors is not always possible. Most use their own communication system and infrastructure, which are not always compatible with other participants’. A goal of this research is to analyse the current situation in terms of the capabilities of the different systems and to propose a solution for the successful interoperability between the different actors in the public safety arena by evaluating both current and improved communication infrastructures with a given scenario using a network simulator. To achieve this goal we analyse the capabilities of broadband communication infrastructure to create a model that describes its capabilities. We also analyse and evaluate the requirements for a communication infrastructure that can handle the daily communication flows, as well as the exceptional traffic that occurs during crises. Our evaluation and analysis is performed on country-level data sets that collect data over a certain period of time. [less ▲]

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See detailDie Bewältigung beruflicher Anforderungen durch Lehrpersonen im ersten Berufsjahr. Eine qualitativ-rekonstruktive Studie über die Merkmale beruflicher Bewältigungsprozesse bei Luxemburger Grundschullehrern.
Lamy, Christian Paul Nico UL

Doctoral thesis (2014)

To succeed, young teachers must rise and meet a range of professional challenges during their first year of teaching. The purpose of this study is to identify how novice teachers, at Luxembourg Elementary ... [more ▼]

To succeed, young teachers must rise and meet a range of professional challenges during their first year of teaching. The purpose of this study is to identify how novice teachers, at Luxembourg Elementary schools, deal with these challenges. This qualitative research study was designed to explore how young teachers perceive and interpret professional challenges and what behaviours they adopt to meet these situations. To analyse the coping processes of young teachers, a heuristical framework was developed, which emphasizes the dynamic relationship between personal and contextual factors and their influence on the perception and decisions of teachers. The study presents and discusses how coping with these challenges always incorporates various types of mental strategies. These findings allow for a better understanding of how young teachers make decisions, which may help direct, for example, future development of induction programmes in support of novice teachers. The main thesis of this study is that overall individual satisfaction among first-year teachers is mainly the result of their own efforts to successfully meet individual needs, such as feeling competent, self consistency, certitude, and being in harmony with personal relationships. To arrive at these insights, 21 first-year teachers were recruited via random selection from a set of volunteers. The study conducted a total of three face-to-face interviews with each of the teachers. To study the progress and changes of how young teachers address the challenges over time, the first interview was conducted before the beginning of the year, the second took place in the middle of the year, and third interview was done at the end of the first year of teaching. Using structuring content analysis methodology, the interviews suggest that personal needs strongly affect both perceptions and reactions among early career teachers over their first year of teaching. This research study provides valuable information regarding the dynamics by which novice teachers meet professional demands, such as assimilative and accommodative strategies, in order to respond to their individual needs. These findings inform and highlight the importance of induction programmes, which ought to take into account the personal, yet very common, needs of first-year teachers. Thus, the aim of induction programmes should be to combine professional development that improves the teaching quality with professional satisfaction, by taking into account, and responding to, first-year individual needs. [less ▲]

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See detailEchternacher Memorialkultur im Hochmittelalter: Das Martyrolog-Nekrolog der Benediktinerabtei Echternach (BnF, lat. 10158). Edition, Kommentar und Analyse
Heirendt, Myriam UL

Doctoral thesis (2014)

Die beachtliche Tätigkeit des Echternacher Skriptoriums im 11. Jh. und die daraus hervorgegangenen kunsthistorisch bedeutenden Prachthandschriften machten Echternach berühmt. Die historisch nicht weniger ... [more ▼]

Die beachtliche Tätigkeit des Echternacher Skriptoriums im 11. Jh. und die daraus hervorgegangenen kunsthistorisch bedeutenden Prachthandschriften machten Echternach berühmt. Die historisch nicht weniger wertvollen Handschriften des 12. Jhs., wie die für den klostereigenen Gebetsdienst angelegten Nekrologien sind hingegen weitestgehend unbekannt. Anhand einer kritischen Edition des Echternacher Martyrolog-Nekrologs aus dem 12. Jahrhundert soll die vorliegende Arbeit eine Forschungslücke im Bereich der Echternacher Memorialtradition schließen und den Grundstein für weiterführende Studien zu der Memoria und der Selbstdarstellung der Willibrordabtei legen. Unterschiedliche methodische Ansätze erlauben es, die Echternacher Memorialtradition aus unterschiedlichen Blickwinkeln zu erfassen und darzustellen. Anhand der kodikologischen Untersuchung der Handschrift und der paläographischen und prosopographischen Analysen konnte der Anlagezeitpunkt der Handschrift und die Frage nach einer konventseigenen Vorlage beantwortet werden. Die engen Verbindungen zum Trierer Kloster Sankt Maximin, die sich nicht nur auf das Gebetsgedenken beschränken, werden neu beleuchtet. Die inhaltliche Verbindung zwischen Martyrolog und Nekrolog eröffnet zwei Interpretationsebenen: die Bedeutung des Gebetsgedenken für das Seelenheil der Verstorbenen und für die Beständigkeit des Reiches. Die Abtei Echternach baute sich ein dichtes Netzwerk an Gedenkbeziehungen auf, die nur vor dem Hintergrund der politisch-religiösen Entwicklungen zwischen dem 10. und dem 12. Jahrhundert verstanden werden können. Dieses Beziehungsgeflecht verdeutlicht das wachsende historische Selbstbildnis der Abtei: eine traditionsreiche Gemeinschaft verankert in der Frühzeit ihrer Gründung und im Reich. Das Bild einer etablierten Reichsabtei, die dem Herrscher treu verbunden ist, festigt sich in der Zeit zwischen dem 10. und dem 12. Jh., wo es seinen Niederschlag im Martyrolog-Nekrolog, dem schriftlichen Gedächtnis der Abtei findet. [less ▲]

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See detailFeature Detection and Classification in Financial News
Minev, Mihail UL

Doctoral thesis (2014)

The thesis concerns the detection of composite features in news articles as well as their significance for the classification's performance. The considered documents are related to the monetary policy ... [more ▼]

The thesis concerns the detection of composite features in news articles as well as their significance for the classification's performance. The considered documents are related to the monetary policy conducted by the Federal Reserve. One principal goal of this work is to quantify embedded information in financial texts by using phrase structure grammar trees in combination with statistical measures and domain knowledge. Thereby, each document is represented as a combination of linguistic features and feature-values. Furthermore, the work examines the correlations between the determined features and an equity market index by modelling the index volatilities as functions of key announcements. A design is targeted, which should enable the temporal tracking of information alterations. Essential aspects of the thesis are the identification, the extraction, and the representation of domain-specific features and their conditional feature-values. [less ▲]

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See detailL'obligation de mise en concurrence et ses limites en droit européen
Niedner, Laurent Jean Henri UL

Doctoral thesis (2014)

Although various pieces of European secondary law law use the terms "mise en concurrence" ("calling for competition" or "competitive tendering procedure") they provide no definition of the expression ... [more ▼]

Although various pieces of European secondary law law use the terms "mise en concurrence" ("calling for competition" or "competitive tendering procedure") they provide no definition of the expression "obligation de mise en concurrence" ("obligation to call for competition"). At the very beginning, the author therefore defines what is meant thereby in his thesis, i.e. "a more or less formalized action which a public or a private person has to follow in order to provoke a competition or a contest between potentially interested persons that perform an economic activity, in order to grant an individual advantage to one or several of them". The first part of the work deals with the regime of competitive tendering of the public procurement directives which the Court of Justice has considered "as a whole" to be the "core" of European law on public contracts. First, this part examins the development of the public procurement directives from 1971 on. The author shows that the puzzling evolution of the personal scope of the public procurement directives is guided by the personal scope of European primary law. While considering the remedies directives, the author examines to what extent they introduce requirements beyond the principle of effective judicial protection. While some of their requirements obviously do so, the remedies directives however remain very far from standardizing the means of redress at national level. Due to the member States' judicial autonomy, the compelling force of EU primary law differs from one member State to another. The same applies within the scope of the remedies directives as they let the member States a large degree of autonomy. The author then turns to examine the contribution of the procurement directives 2004/17/CE, 2004/18/CE and 2009/81/CE, their scope of application, as well as the concepts of public works concession and service concession. Various other questions are dealt with in the first part, such as the use of functional interpretation, the power of the European legislator to adopt regulations on public procurement and the impact of the Agreement on Government Procurement (GPA), the Revised GPA and other international agreements. At last the author explores the issue of electronic procurement and the Commission's proposals for replacing the public procurement directives 2004/17/CE and 2004/18/CE and its proposal concerning the award of concession contracts. The second part of of the thesis focuses on primary public procurement law. After having described the origin of the obligation to call for competition under EU primary law which the Court of Justice derives from articles 49 and 56 TFEU as well as from the principles of equal treatment and non-discrimination on the grounds of nationality, the author strives to determine whether this obligation is well-founded. This examination brings to light that the rationale behind the requirement to call for competition under EU primary law is rather fragile. Amongst others, the author comes to the conclusion that the condition of a certain cross-border interest of each public contract individually as a condition for the application of the primary law obligation to call for competition lacks relevance The author then reviews and examines other possible bases for an obligation to call for competition under EU primary law such as the right to good administration, the freedom of enterprise and the right to property, which are protected by the Charter of Fundamental Rights, and the rights guaranteed by the European Convention on Human Rights. Finally, it seems that only article 102 TFEU (abuse of a dominant position) could to a limited extent give rise to an obligation to call for competition. However, once a situation is governed by EU secondary law, it enters the scope of European law. Hence, the principles of equal treatment and of non-discrimination on the grounds of nationality apply even if a situation involves no cross-border interest. If the Court of justice's case law were followed consistently, these principes should lead to require calls for competition in a number of purely internal situations. According to the author, deducing as precise consequences as does the Court of justice from the principal of equal treatment and other fundemental principles can hardly be justified. After that examination, the material rules of public procurement primary law stated by the Court of Justice and the General Court are successively reviewed. The pages that follow are about the exceptions to the obligation to call for competition under the public procurement directives and under primary law, as for instance articles 51 and 52 TFEU, overriding reasons of general interest and article 106, paragraph 2, TFEU. The author thereafter addresses the question whether primary law applies within the scope of secondary law. He comes to the conclusion that it does even when secondary law represents an exhaustive body of rules. Notwithstanding some ambiguous judgements of the Court of justice there is no support for the doctrine of priority of application of secondary law in the Court's case law. In what follows, the author tries to answer the question whether, in order to stay consistent with the case law developed in the wake of Telaustria, the obligation to call for competition which the case law of the Court of Justice requires for public works, service and supply contracts ought to be extended to other operations (sale or lease of real estate, design contests outside the scope of the public procurement directives, employment contracts, subsidised contracts awarded by private entities outside the scope of the public procurement directives, grants, …). The end of the second part deals with the personal scope of the primary law of public procurement which corresponds to that of EU primary law. The rules concerning State aid are addressed in detail in the third part of the thesis. The examination in that part shows that the public procurement directives, the primary law of public procurement and the EU state aid rules apply cumulatively. The EU State aid rules require efficency when awarding public contracts. Nevertheless, in order to avoid the categorization as State aid, a call for competition is never formally required. The Commission however insists on calls for competition in order to declare certain aids compatible with the internal market. Aids include by definition an advantage for their recipients. This remains true even though an aid has been authorised by the Commission pursuant to article 107, paragraphe 3, TFEU. Given the very broad scope the Court of Justice gives to the freedom of establishment and the free movement of services, aid measures give generally rise to obstacles to the freedom of establishment and the free movement of services. At the risk of rendering article 107, paragraph 3, TFEU unnecessary, the fact that an aid measure impedes the fundamental freedoms of the internal market should therefore not prevent the Commission to declare it compatible with the internal market. This applies in particular to aids consisting in the award of a public contract that is covered only by EU primary law. That solution seems however excluded for public contracts within the scope of the public procurement directives. The Commission has adopted a broad concept of what is an "advantage" in the sense of the State aid rules. This leads the Commission to consider certain grants for environmental protection as State aid measures even though it may be difficult to dectect any kind of advantage. The Commission claims to control these measures in accordance with the rules of State aid control. On that occasion the Commission tends to make its consent subject to a call for competition in order to identify the projects that will be subsidized. A broad approach of the concept of undertaking leads to class as State aid various public infrastructure investments insofar they do not satisfy the private investor test. The Commission tends to make its consent to these investments subject to calls for competition. Such is notably the case regarding public investments in broadband network facilities. In the fourth part, the author examines a variety of secondary legislation imposing calls for competition other than the public procurement directives. These texts cover a wide range of areas and provide for competitive awards of various form and diverse content. Sometimes a requirement for competitive tendering is overtly expressed. At other times, it is implicit, indirect or just inchoate. Some advantages are awarded without a genuine competition or without any competition at all. Directive 2012/34/CE establishing a single European railway area for instance sets principles for the allocation of "infrastructure capacity" (i.e the right to use a railway network). It does not employ such terms as "calling for competition". Where the infrastructure capacity is insufficient it has to be allocated in a fair and non discriminatory manner. The fee for using the railway network cannot be used as an award criterion. In some areas, competition in terms of price is the very basis of the system. This is true for the greenhouse gas emissions trading scheme. It happens that competitive assignment occurs incidentally and in a non compulsory way as in the case of the milk quota regime. In other cases, e.g. certain situations covered by the internal electricity market regime, the system excludes calls for competition whereas they should be required according to primary procurement law principles. Under still other circumstances, i.e. the award of public service contracts for public passenger transport services, competitive tendering only needs to be strictly complied with after a transitional period. This can hardly be reconciled with the principles of primary procurement law. In some cases the rules in place are such, for example when awarding the universal postal service, that it seems doubtful that a competitive bidding following objective and transparent criteria is really possible. The European greenhouse gas emissions trading scheme relies on auctions for the allocation of gaz emission authorisations. At first, it does so to a limited extent. Such authorisations, called "allowances", are freely transferable. Thus a reallocation of allowances according to market mechanismes is made possible. The author sheds light on some major inconsistencies of the greenhouse gas emission trading scheme. The late deadline for surrendering allowances gives rise for several years to a surplus of allowances over the greenhouse gas emissions considered in the scheme. On the other hand, the costs for same amounts of greenhouse gas emitted at the same time may vary. This gives rise to a problem of equality. The author comes to the conclusion that the scheme has little capacity to reach the objective of reducing greenhouse gas emissions at least cost to the economy. The designation of the universal postal service providers implies to lay down rules as to how the net cost of the universal service is to be calculated, as well as to define appropriate award criteria. These steps face considerable difficulties. A similar situation can be found in other areas such as electronic communications and electricity or natural gas transmission or distribution systems. In the latter case, the risk of a change of transmission or distribution tariffs due to decisions of national regulatory authorities leaves the competitors in the dark on a crucial point. The legislation regarding the internal electricity market and the internal gaz market puts the transmission and distribution system operators in a position very similar to that of service or public works concession holders. In some cases the principles which underlie these schemes exclude competitive tendering as required by primary procurement law. The networks being freely transferable, ownership of networks and hence, in principle, their operators are determined by private market mechanismes mainly through the level of the proposed sales price. This is not consistent with the principles of primary procurement law stated by the Court of Justice (advertising requirements, award criteria linked to the subject matter of the contract, ...) . Neither does it seem compatible with these principles that the development of the networks belongs automatically to the transmission and distribution system operators. The assessment of conformity of secondary legislation with primary law is less strict than the conformity assessment of national law. The Court of Justice has allowed the European legislator a wide margin of discretion when establishing the internal market and seems to have tacitely acknowledged a form of conformity presumption of secondary law. Save in exceptional cases, it seems unlikely that the Court will put into question secondary law regimes differing from primary law procurement rules. Thus, the European legislator may adopt such solutions without incurring major legal risks. [less ▲]

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See detailThe Outsourcing of Legal Service to India: Trends, Challenges and Potential
Singh Chauhan, Dharamveer UL

Doctoral thesis (2014)

The outsourcing of legal services to India is becoming increasingly popular among U.S. and U.K. law firms and corporations. This thesis seeks to discuss three main topics surrounding legal process ... [more ▼]

The outsourcing of legal services to India is becoming increasingly popular among U.S. and U.K. law firms and corporations. This thesis seeks to discuss three main topics surrounding legal process outsourcing (LPO): its emerging trends, the legal challenges it raises and the hitherto unrecognized potential it holds. Firstly, this thesis clarifies concepts of LPO and its operating models practiced by U.S. and U.K. law firms and corporations. Whenever there is outsourcing in the manufacturing or service sectors, concerns over job losses in the domestic territory are raised by politicians and policy-makers. Accordingly, this research critically discusses the impact of outsourcing on unemployment with a particular focus on legal sector jobs. Secondly, the outsourcing of legal services creates significant challenges for ethics rules and data protection laws. The act of sending legal work overseas by U.S. lawyers may violate American legal ethics rules including those related to conflicts of interest, supervision, fee- sharing, client confidentiality, and attorney-client privilege. Self-regulation is the hallmark of the U.S. legal profession. This thesis therefore reflects, in the first instance, upon the issue of the independence of lawyers who have established a ‘sheltered’ industry for themselves by creating rules that prevent non-lawyers from practicing law. Thereafter, acknowledging the presence of the U.S. legal ethics rules, this thesis provides an explanation as to how a U.S. lawyer could outsource legal works to India without compromising core legal ethics rules. Thirdly, this research explores the hidden potential of LPO to improve access to justice. The outsourcing of legal services to India suffers from a negative image among certain sections of the American legal profession, but has only been discussed so far in the context of law firms and corporations. This thesis develops an altogether new proposal where Indian LPO professionals could help alleviate the access to justice problem among indigent and low-income populations of the United States. [less ▲]

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See detailThe Interactions of HLA class I Molecules with their Receptors and its Effects on NK Cells
Sleiman, Marwan UL

Doctoral thesis (2014)

The role of HLA class I molecule interaction with their receptors in NK cell education is well established, but the molecular mechanism behind it as well as the role of these ligands on their receptors ... [more ▼]

The role of HLA class I molecule interaction with their receptors in NK cell education is well established, but the molecular mechanism behind it as well as the role of these ligands on their receptors acquisition during NK cell development, are still unclear. Trying to give more insight to these questions, two different studies were performed on NK cells derived from patients presenting a genetic defect in the transporter associated with antigen processing (TAP), leading to a strongly reduced surface expression of HLA class I molecules. In our first paper, the expression of HLA class I receptors (three killer immunoglobulin-like receptors (KIR) - KIR2DL1/DS1, KIR2DL2/3/DS2 and KIR3DL1 - NKG2A, CD8) and the maturation marker CD57 were dissected in seven TAP-deficient patients and a panel of healthy donors (HD). A comparison of the two NK cell statuses (healthy and TAP-deficient) showed a significant increase in HLA class I receptors’ co-expression in TAP-deficient compared to healthy NK cells. Functionally, hyporesponsiveness was confirmed for TAP-deficient NK cells: no cytotoxicity, degranulation nor IFN-γ production following co-culture with K562 cells. Only one patient presented functional NK cells with HLA class I receptors’ co-expression pattern being different form HD’s one. In parallel, whole genome microarrays were performed on TAP-deficient vs HD’s NK cells, aiming to identify the maturation (from CD56bright to CD56dim) as well as cytotoxicity pathways which may be affected by HLA class I expression. The comparison of both statuses showed similar maturation processes (with different CD56bright and CD56dim gene profiles). Following 5 hours of CD56dim NK cells co-incubation with K562 cells, different gene clusters’ evolution lead to identical final profiles contradicting the significant functional difference. Taken together, our data demonstrate a strong effect of HLA class I molecules on NK cell maturation and functionality as well as on their KIR repertoire formation. [less ▲]

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See detailSecurity Aspects of Symmetric-Key Primitives
Roy, Arnab UL

Doctoral thesis (2014)

In this thesis we discuss security aspects of three symmetric-key primitives – Block Cipher, Hash function and MAC (Message Authentication Codes). More specifically, we present the results of our analysis ... [more ▼]

In this thesis we discuss security aspects of three symmetric-key primitives – Block Cipher, Hash function and MAC (Message Authentication Codes). More specifically, we present the results of our analysis on some ARX based hash functions and block ciphers. We analyse the security of recently proposed light-weight block ciphers – SIMON and SPECK. We give a generic graph based method to compute differential probability of bitwise AND with independent and rotationally dependent inputs. Using this algorithm we apply the automatic differential trail searching method for SIMON. We show the results of this search technique, extended for searching differential and applied to both SIMON and SPECK. Using this differential analysis we could perform key recovery attacks on reduced rounds of SIMON and SPECK for different key sizes. We present the results on boomerang analysis of the SHA-3 candidates Skein and BLAKE. Using some modifications to the classic boomerang analysis technique we show second order differential attacks on both the hash functions for reduced rounds. As a result of this analysis we also identify a problem in applying boomerang attacks to ARX designs, which is the reason for non-returning boomerangs in such attacks. For the security analysis of MACs, we show related-key attacks on some popular MACs using a class of (claw-free) related-key deriving functions defined by adversary. In context to several related key attacks on well known block ciphers including AES, a natural concern is the related-key security of MAC which could be designed using such ciphers. We show that using related-key unpredictable function(or permutation) it is possible to design a related-key secure MAC. This is also equivalent to the secure domain extension under related-key unforgeability. We propose a variant Merkle-Damgård iteration to achieve this. We also analyse and improve a generic masking technique, which is used to prevent block cipher implementations from side-channel attacks. We present results of our analysis of a generic higher-order masking technique for S-boxes. This generic masking technique is efficient in software.Itrequiresefficientevaluationofpolynomialsinfinitefield,specificallyinF2n because every S-box can be expressed as a polynomial in a suitable finite field. More specifically, the efficiency of the masking algorithm depends on the number of multiplications(non-squaring) in a finite field. We propose an efficient polynomial evaluation technique to give an improved generic higher-order masking scheme. Using our method we show that we can improve the masking scheme for DES, CLEFIA, CAMELLIA. [less ▲]

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See detailModelling Heterogeneous Reactions In Packed Beds and Its Application to The Upper Shaft of A Blast Furnace
Hoffmann, Florian UL

Doctoral thesis (2014)

Heterogeneous reactions in packed beds such as iron ore reduction or gasification of coke in a blast furnace involve various aspects of thermodynamics, fluid dynamics, chemistry and physics. Unfortunately ... [more ▼]

Heterogeneous reactions in packed beds such as iron ore reduction or gasification of coke in a blast furnace involve various aspects of thermodynamics, fluid dynamics, chemistry and physics. Unfortunately, inaccessible and hostile process environments make it very difficult to gain insights into such reactors and to operate the industrial processes. To address this problem extensive research has been undertaken in the past to develop numerical methods and models. However, little effort has been made to describe the complex thermochemical processes inside such reactors starting from the particle and especially intra-particle scale. The objectives of this thesis are to introduce a coupled approach which allows for the physical and chemical interaction of a granular material with a surrounding gas phase and to apply it to the reduction processes in the upper shaft of a blast furnace. Furthermore, a suitable model to investigate the gas-solid thermochemical interaction within a single particle and within a packed bed of particles was to be established. Thus, the classical discrete element method (DEM) was extended by thermodynamic state variables such as temperature, composition and chemical reactions. In addition, a coupling between the particulate phase and a continuous gas phase for convective heat and mass transfer was implemented. It should be noted that the application of the presented methodology is not only restricted to the blast furnace, but rather represents a rigorous approach that can be applied to other packed bed reactors as well. A validation study on the particle scale using experimental results shows that the dis- crete particle model accurately predicts the progress of indirect reduction of a pellet. The particle model is shown to be capable of resolving radial gradients on the particle scale avoiding rigorous assumptions or mathematical fits to a specific experimental setup. These qualities of the model permit its usage in the presented analysis of indirect reduc- tion within the shaft of a blast furnace where each particle is subjected to time-varying boundary conditions. On the packed bed scale heat and mass transfer from the discrete to the continuous phase was validated using experimental data. Moreover, the model showed accurate results when compared to experimental reduction data from a lab scale bed of iron ore particles. Finally, the reduction processes in the upper shaft of a blast furnace were analysed: Firstly, isothermal reduction of a packed bed of pellets according to ISO standards were analysed in terms of heterogeneity in temperature and reduction degree inside the cylindrical reactor. Results indicate that radial gradients inside the packed bed are caused by the higher mass flow rate close to the reactor wall. Axial gradients develop due reduction reactions and the direction of the fluid flow. The formation of these axial gradients is found to be inherent to the process of indirect reduction of iron oxides due to the sequence of exothermic and endothermic reaction steps. Secondly, a complex packed bed with a layered structure of coke and iron ore particles is analysed under time-varying reducing gas conditions simulating the journey of a packed bed column through the upper shaft of a blast furnace. Results highlight that the gas and the solid phase are highly coupled in space and time during the process of indirect reduction. Axial gradients in temperature and composition form due to the heat and mass transfer between the packed bed and the streaming gas. Energy released or consumed by the indirect reduction provides an opposing trend to the gradients formed from the hot gas stream, thus reducing axial gradients within the bed and the gas phase. The results indicate the mechanisms involved during the formation of the thermal reserve zones inside the blast furnace shaft due to the complex interaction of convective heat and mass transfer in conjunction with energy consumption and release by the reactions. Considering the findings presented, this thesis is understood to contribute to the better understanding of heterogeneous reactions in packed beds and as a particular example of such the upper part of the blast furnace. [less ▲]

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See detailLa légalité de la preuve dans l'espace pénal européen
Marty, Marie UL

Doctoral thesis (2014)

La recevabilité de la preuve est sans doute l’une des questions les plus importantes de l’espace de liberté, de sécurité et de justice de l’Union européenne, mais aussi une des plus complexes. Les ... [more ▼]

La recevabilité de la preuve est sans doute l’une des questions les plus importantes de l’espace de liberté, de sécurité et de justice de l’Union européenne, mais aussi une des plus complexes. Les difficultés relatives à l’utilisation d’une preuve recueillie dans un État membre, devant les juridictions répressives d’un autre État membre, semblent cependant avoir été sous-estimées par le législateur européen. En effet, l’amélioration de l’efficacité de la répression transnationale a été une des priorités de la politique criminelle de l’Union ces quinze dernières années. À ce titre, le renforcement des mécanismes de coopération judiciaire, y compris ceux visant à l’obtention de la preuve transnationale, a été privilégié. Grâce au principe de reconnaissance mutuelle des décisions judiciaires en matière pénale, fondé sur la confiance réciproque que les États membres se portent, les divergences et éventuelles incompatibilités entre les systèmes nationaux ont été tenues en échec, permettant ainsi la libre circulation des preuves dans l’espace pénal européen. Cependant, cette justification théorique n’est pas suffisante pour assurer la recevabilité mutuelle des preuves, la bonne administration de la preuve pénale demeurant une question nationale, souverainement appréciée par le juge national. De plus, tant l’étude comparative des régimes probatoires nationaux que la présentation des instruments de coopération judiciaire montrent des déficiences profondes, appelant ainsi à une protection accrue et harmonisée des droits fondamentaux dans les procédures répressives au niveau européen, dans le but d’assurer la recevabilité mutuelle des preuves pénales dans l’espace pénal européen. [less ▲]

Detailed reference viewed: 158 (19 UL)
See detailInnovation, learning and construal levels in the modern workplace
Reyt, Jean-Nicolas Alfred Jules UL

Doctoral thesis (2014)

Knowledge is increasingly recognized as one of the most critical resources in the modern workplace, because the way knowledge is learned, shared and used determines organizational innovation and ... [more ▼]

Knowledge is increasingly recognized as one of the most critical resources in the modern workplace, because the way knowledge is learned, shared and used determines organizational innovation and effectiveness. In this dissertation, we build on construal level theory to explore the relationship between the structure of workers’ roles and the types of knowledge that workers create and share. In particular, we draw upon two features of the modern workplace that are evolving dramatically – the increasing use of technology and changing hierarchical structures – to explore how the level of abstraction at which employees mentally represent their work roles mediates the relationship between these structural features of the work context and the practically-relevant and important employee behaviors underlying innovation. We leverage methodological diversity to test the hypotheses in several studies, including studies based on archival data, experiments and longitudinal studies based on survey data. [less ▲]

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See detailFault Detection and Network Security in Software-Defined Networks with OpenFlow
Hommes, Stefan UL

Doctoral thesis (2014)

Due to the rigid architecture of most switches and routers, which provide functionality only for a certain application scenario, the flexibility of deploying new network functions is limited. The advent ... [more ▼]

Due to the rigid architecture of most switches and routers, which provide functionality only for a certain application scenario, the flexibility of deploying new network functions is limited. The advent of programmable networks, which is described as Software-Defined Networking (SDN), allows the extension and control of networks based on a flexible con- trol plane, which is based on software and acts as a network operating system with network applications running on top of it. In this thesis we focussed on SDN based on the concept of the OpenFlow protocol. In or- der to deploy such networks in operational environments and datacentres, the challenges concerning network management are still lacking a sufficient analysis and are further investigated in this thesis, which examines the reliability and maintainability of SDN, as well as new security issues that are introduced with this architecture. The second contribution of this thesis is to provide solutions to some of the addressed challenges, with a focus on fault detection and network security. With regard to fault detection, we discuss the information content and monitoring as- pects of flow entries that are located on the network devices, but are managed from the network controller. This involves applying methods from information theory to deter- mine faults and attacks by observing the logical topology, and correlation facilities to determine errors that relate to the data plane. In network security, current approaches mostly rely on security appliances that are de- ployed at different locations in the network. We analyse the extend to which SDN can be leveraged to provide new ways of thwarting network attacks, and investigate the pos- sibilities for controller-based packet inspection to detect malicious communications in the network. This includes the extraction of hidden communication patterns originating from a stealthy backdoor. The freedom of extending controller software to meet new network service requirements comes at a high cost. Since the reliability of the network must be assured, tools are required to debug and test the software after each alteration step. We propose a solu- tion that instruments network applications with additional code for logging purposes, guaranteeing certain correctness properties. In combination with a database system, our framework can be leveraged to allow network debugging or anomaly detection. [less ▲]

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See detailEFFECTS OF EUROPEAN INTEGRATION ON PARLIAMENTARY CONTROL OF GOVERNMENT: THE CASE OF LUXEMBOURG, 1999-2011
Spreitzer, Astrid Petra UL

Doctoral thesis (2014)

The present thesis sets out to provide an understanding of how European integration affects NPs in the EU and their relationship to the executive. The main objective of the empirical analysis is to ... [more ▼]

The present thesis sets out to provide an understanding of how European integration affects NPs in the EU and their relationship to the executive. The main objective of the empirical analysis is to investigate how parliamentary control of government serves EU scrutiny between 1999 and 2011. The case study, which focuses on the Luxembourgish Chamber of Deputies allows for a test of changes in governmental discretion on three parliamentary control dimensions in different domestic and European contexts of coalition governments and European Treaties. The theoretical framework for interpreting the impact of the EU on NPs and executive-legislative relations is a combination of the larger concept of top-down Europeanisation with the principal agent approach. The emphasis is on the EU as an external force being central in the adaptation of parliamentary control of government, while taking into account the particularity of parliament as a principal. Based on the delegation argument, we generate hypotheses about the evolution of parliamentary democracy under the condition of a highly decentralised committee system, multiple committee membership, high party cohesion and majority government. Our empirical findings run counter to the predictions of the deparliamentarisation hypothesis. This owes to the fact that we investigate parliamentary control of government in a most inclusive perspective. Rather than weakened, this study considers the Luxembourgish parliament strengthened not least by the opportunities offered by the Lisbon Treaty. In complicity, it backs up a government which has lost on discretion at EU level. [less ▲]

Detailed reference viewed: 316 (101 UL)