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See detailEssays on the macro-analysis of international migration
Delogu, Marco UL

Doctoral thesis (2016)

This dissertation consists of three chapters, all of them are self-contained works. The first chapter, “Globalizing labor and the world economy: the role of human capital” is a joint work with Prof. Dr ... [more ▼]

This dissertation consists of three chapters, all of them are self-contained works. The first chapter, “Globalizing labor and the world economy: the role of human capital” is a joint work with Prof. Dr. Frédéric Docquier and Dr. Joël Machado. We develop a microfounded model of the world economy aiming to compare short- and long-run effects of migration restrictions on the world distribution of income. We find that a complete removal of migration barriers would increase the world average level of GDP per worker by 13% in the short run and by about 54% after one century. These results are very robust to our identification strategy and technological assumptions. The second chapter, titled “Infrastructure Policy: the role of informality and brain drain” analyses the effectiveness of infrastructure policy in developing countries. I show that, at low level of development, the possibility to work informally has a detrimental impact on infrastructure accumulation. I find that increasing the tax rate or enlarging the tax base can reduce the macroeconomic performance in the short run, while inducing long-run gains. These effects are amplified when brain drain is endogenous. The last chapter, titled “The role of fees in foreign education: evidence from Italy and the UK” is mainly empirical. Relying upon a discrete choice model, together with Prof. Dr. Michel Beine and Prof. Dr. Lionel Ragot I assess the determinants of international students mobility exploiting, for the first time in the literature, data at the university level. We focus on student inflows to Italy and the UK, countries on which tuition fees varies across universities. We obtain evidence for a clear and negative impact of tuition fees on international students inflows and confirm the positive impact of quality of education. The estimations find also support for an important role of additional destination-specific variables such as host capacity, expected return of education and cost of living in the vicinity of the university. [less ▲]

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See detailAUTOMATED TESTING OF SIMULINK/STATEFLOW MODELS IN THE AUTOMOTIVE DOMAIN
Matinnejad, Reza UL

Doctoral thesis (2016)

Context. Simulink/Stateflow is an advanced system modeling platform which is prevalently used in the Cyber Physical Systems domain, e.g., automotive industry, to implement software con- trollers. Testing ... [more ▼]

Context. Simulink/Stateflow is an advanced system modeling platform which is prevalently used in the Cyber Physical Systems domain, e.g., automotive industry, to implement software con- trollers. Testing Simulink models is complex and poses several challenges to research and prac- tice. Simulink models often have mixed discrete-continuous behaviors and their correct behav- ior crucially depends on time. Inputs and outputs of Simulink models are signals, i.e., values evolving over time, rather than discrete values. Further, Simulink models are required to operate satisfactory for a large variety of hardware configurations. Finally, developing test oracles for Simulink models is challenging, particularly for requirements capturing their continuous aspects. In this dissertation, we focus on testing mixed discrete-continuous aspects of Simulink models, an important, yet not well-studied, problem. The existing Simulink testing techniques are more amenable to testing and verification of logical and state-based properties. Further, they are mostly incompatible with Simulink models containing time-continuos blocks, and floating point and non- linear computations. In addition, they often rely on the presence of formal specifications, which are expensive and rare in practice, to automate test oracles. Approach. In this dissertation, we propose a set of approaches based on meta-heuristic search and machine learning techniques to automate testing of software controllers implemented in Simulink. The work presented in this dissertation is motived by Simulink testing needs at Delphi Automotive Systems, a world leading part supplier to the automotive industry. To address the above-mentioned challenges, we rely on discrete-continuous output signals of Simulink models and provide output- based black-box test generation techniques to produce test cases with high fault-revealing ability. Our algorithms are black-box, hence, compatible with Simulink/Stateflow models in their en- tirety. Further, we do not rely on the presence of formal specifications to automate test oracles. Specifically, we propose two sets of test generation algorithms for closed-loop and open-loop con- trollers implemented in Simulink: (1) For closed-loop controllers, test oracles can be formalized and automated relying on the feedback received from the controlled system. We characterize the desired behavior of closed-loop controllers in a set of common requirements, and then use search to identify the worst-case test scenarios of the controller with respect to each requirement. (2) For open-loop controllers, we cannot automate test oracles since the feedback is not available, and test oracles are manual. Hence, we focus on providing test generation algorithms that develop small effective test suites with high fault revealing ability. We further provide a test case prioriti- zation algorithm to rank the generated test cases based on their fault revealing ability and lower the manual oracle cost. Our test generation and prioritization algorithms are evaluated with several industrial and publicly available Simulink models. Specifically, we showed that fault revealing ability of our our approach outperforms that of Simulink Design Verifier (SLDV), the only test generation toolbox of Simulink and a well-known commercial Simulink testing tool. In addition, using our approach, we were able to detect several real faults in Simulink models from our industry partner, Delphi, which had not been previously found by manual testing based on domain expertise and existing Simulink testing tools. Contributions. The main research contributions in this dissertation are: 1. An automated approach for testing closed-loop controllers that characterize the desired be- havior of such controllers in a set of common requirements, and combines random explo- ration and search to effectively identify the worst-case test scenarios of the controller with respect to each requirement. 2. An automated approach for testing highly configurable closed-loop controllers by account- ing for all their feasible configurations and providing strategies to scale the search to large multi-dimensional spaces relying on dimensionality reduction and surrogate modelling 3. A black-box output-based test generation algorithm for open-loop Simulink models which uses search to maximize the likelihood of presence of specific failure patterns (i.e., anti- patterns) in Simulink output signals. 4. A black-box output-based test generation algorithm for open-loop Simulink models that maximizes output diversity to develop small test suites with diverse output signal shapes and, hence, high fault revealing ability. 5. A test case prioritization algorithm which relies on output diversity of the generated test suites, in addition to the dynamic structural coverage achieved by individual tests, to rank test cases and help engineers identify faults faster by inspecting a few test cases. 6. Two test generation tools, namely CoCoTest and SimCoTest, that respectively implement our test generation approaches for closed-loop and open-loop controllers. [less ▲]

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See detailDomain Completeness of Model Transformations and Synchronisations
Nachtigall, Nico UL

Doctoral thesis (2016)

The intrinsic question of most activities in information science, in practice or science, is “Does a given system satisfy the requirements regarding its application?” Commonly, requirements are expressed ... [more ▼]

The intrinsic question of most activities in information science, in practice or science, is “Does a given system satisfy the requirements regarding its application?” Commonly, requirements are expressed and accessible by means of models, mostly in a diagrammatic representation by visual models. The requirements may change over time and are often defined from different perspectives and within different domains. This implies that models may be transformed either within the same domain-specific visual modelling language or into models in another language. Furthermore, model updates may be synchronised between different models. Most types of visual models can be represented by graphs where model transformations and synchronisations are performed by graph transformations. The theory of graph transformations emerged from its origins in the late 1960s and early 1970s as a generalisation of term and tree rewriting systems to an important field in (theoretical) computer science with applications particularly in visual modelling techniques, model transformations, synchronisations and behavioural specifications of models. Its formal foundations but likewise visual notation enable both precise definitions and proofs of important properties of model transformations and synchronisations from a theoretical point of view and an intuitive approach for specifying transformations and model updates from an engineer’s point of view. The recent results were presented in the EATCS monographs “Fundamentals of Algebraic Graph Transformation” (FAGT) in 2006 and its sequel “Graph and Model Transformation: General Framework and Applications” (GraMoT) in 2015. This thesis concentrates on one important property of model transformations and synchronisations, i.e., syntactical completeness. Syntactical completeness of model transformations means that given a specification for transforming models from a source modelling language into models in a target language, then all source models can be completely transformed into corresponding target models. In the same given context, syntactical completeness of model synchronisations means that all source model updates can be completely synchronised, resulting in corresponding target model updates. This work is essentially based on the GraMoT book and mainly extends its results for model transformations and synchronisations based on triple graph grammars by a new more general notion of syntactical completeness, namely domain completeness, together with corresponding verification techniques. Furthermore, the results are instantiated to the verification of the syntactical completeness of software transformations and synchronisations. The well-known transformation of UML class diagrams into relational database models and the transformation of programs of a small object-oriented programming language into class diagrams serve as running examples. The existing AGG tool is used to support the verification of the given examples in practice. [less ▲]

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See detailPopulating Legal Ontologies using Information Extraction based on Semantic Role Labeling and Text Similarity
Humphreys, Llio Bryn UL

Doctoral thesis (2016)

This thesis seeks to address the problem of the 'resource consumption bottleneck' of creating (legal) semantic technologies manually. It builds on research in legal theory, ontologies and natural language ... [more ▼]

This thesis seeks to address the problem of the 'resource consumption bottleneck' of creating (legal) semantic technologies manually. It builds on research in legal theory, ontologies and natural language processing in order to semi-automatically normalise legislative text, extract definitions and structured norms, and link normative provisions to recitals. The output is intended to help make laws more accessible, understandable, and searchable in a legal document management system. Key contributions are: - an analysis of legislation and structured norms in legal ontologies and compliance systems in order to determine the kind of information that individuals and organisations require from legislation to understand their rights and duties; - an analysis of the semantic and structural challenges of legislative text for machine understanding; - a rule-based normalisation module to transform legislative text into regular sentences to facilitate natural language processing; - a Semantic Role Labeling based information extraction module to extract definitions and norms from legislation and represent them as structured norms in legal ontologies; - an analysis of the impact of recitals on the interpretation of legislative norms; - a Cosine Similarity based text similarity module to link recitals to relevant normative provisions; - a description of important challenges that have emerged from this research which may prove useful for future work in the extraction and linking of information from legislative text. [less ▲]

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See detailDevelopment of biospecimen quality control tools and disease diagnostic markers by metabolic profiling
Trezzi, Jean-Pierre UL

Doctoral thesis (2016)

In metabolomics-based biomarker studies, the monitoring of pre-analytical variations is crucial and requires quality control tools to enable proper sample quality evaluation. In this dissertation work ... [more ▼]

In metabolomics-based biomarker studies, the monitoring of pre-analytical variations is crucial and requires quality control tools to enable proper sample quality evaluation. In this dissertation work, biospecimen research and machine learning algorithms are applied (1) to develop sample quality assessment tools and (2) to develop disease-specific diagnostic models. In this regard, a novel plasma sample quality assessment tool, the LacaScore, is presented. The LacaScore plasma quality assessment is based on the plasma levels of ascorbic acid and lactic acid. The biggest challenge in metabolomics analyses is that the sample quality is often not known. The presented tool enhances the knowledge and importance of the monitoring of pre-analytical variations, such as pre-centrifugation time and temperature, prior to sample analysis in the emerging field of metabolomics. Based on the LacaScore, decisions on the suitability/fit-for-purpose of a given sample or sample cohort can be made. In this dissertation work, the knowledge on sample quality was applied in a biomarker discovery study based on cerebrospinal fluid (CSF) from early-stage Parkinson’s disease (PD) patients. To date, no markers for the diagnosis of Parkinson’s disease are available. In this work, a non-targeted GC-MS approach is presented and shows significant changes in the metabolic profile in CSF from early-stage PD patients compared to matched healthy control subjects. Based on these findings, a biomarker signature for the prediction of earlystage PD has been developed by the application of sophisticated machine learning algorithms. This disease-specific signature is composed of metabolites involved in inflammation, glycosylation/glycation and oxidative stress response. In summary, this dissertation illustrates the importance of sample quality monitoring in biomarker studies that are often limited by small amounts of human body fluids. The monitoring of sample quality enhances the robustness and reproducibility of biomarker discovery studies. In addition, proper data analysis and powerful machine learning algorithms enable the generation of potential disease diagnosis biomarker signatures. [less ▲]

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See detailPrediction of drug targets using metabolic modelling
Bintener, Tamara Jean Rita UL

Bachelor/master dissertation (2016)

Cancer, as one of the leading causes of death worldwide, is a disease characterized by the abnormal and uncontrolled proliferation of cells. Currently available anti-cancer drugs come with a variety of ... [more ▼]

Cancer, as one of the leading causes of death worldwide, is a disease characterized by the abnormal and uncontrolled proliferation of cells. Currently available anti-cancer drugs come with a variety of different side effects reducing the quality of life of cancer patients. Due to these severe side effects in anti-cancer therapy it is important to find a compromise between killing the cancer cells (efficiency) and not affecting the healthy cells (toxicity) to improve the quality of life of those patients. There exist different methods of finding new drug targets in cancer such as the in vitro development of new drugs which is very time consuming and expensive. The in silico prediction of targets, on the other hand, is fast and cost effective and allows to make a pre-selection of drug targets based on candidate genes. In this work, I propose a new workflow which implements metabolic modelling for finding metabolic drug targets in cancer. Therefore, context-specific models for cancer (including primary and metastatic melanoma) and healthy controls were reconstructed from Recon 2 (a genome scale metabolic model) using FASTCORMICS and two different expression datasets. In silico single gene deletion was performed in the models to search for potential candidate genes which are essential in cancer (reduce biomass production by 50%) but not in healthy (do not affect ATP production). In a second step, (approved) drugs targeting metabolic genes and their side effects, were extracted from the DrugBank, STITCH and SIDER through data mining and mapped to the metabolic network. A total of 65 possible drug targets have been found. These targets include genes which are known targets for chemotherapeutic agents such as the thymidylate synthase (TYMS), the fatty acid synthase (FASN) or dihydrofolate reductase (DHFR). Furthermore, two anti-cancer agents have been predicted for FASN which have already been proposed for the treatment of cancer. [less ▲]

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See detailIn vitro Metabolic Studies of Dopamine Synthesis and the Toxicity of L-DOPA in Human Cells
Delcambre, Sylvie UL

Doctoral thesis (2016)

This work is divided in two parts. In the first, I investigated the effects of 2,3- dihydroxy-L-phenylalanine (L-DOPA) on the metabolism of human tyrosine hydroxylase (TH)-positive neuronal LUHMES cells ... [more ▼]

This work is divided in two parts. In the first, I investigated the effects of 2,3- dihydroxy-L-phenylalanine (L-DOPA) on the metabolism of human tyrosine hydroxylase (TH)-positive neuronal LUHMES cells. L-DOPA is the gold standard treatment for Parkinson’s disease (PD) and its effects on cellular metabolism are controversial. It induced a re-routing of intracellular carbon supplies. While glutamine contribution to tricarboxylic acid (TCA) cycle intermediates increased, glucose contribution to the same metabolites decreased. Carbon contribution from glucose was decreased in lactate and was compensated by an increased pyruvate contribution. Pyruvate reacted with hydrogen peroxide generated during the auto-oxidation of L-DOPA and lead to an increase of acetate in the medium. In the presence of L-DOPA, this acetate was taken up by the cells. In combination with an increased glutamate secretion, all these results seem to point towards a mitochondrial complex II inhibition. In the second part of this work, I studied and compared dopamine (DA)-producing in vitro systems. First, I compared gene and protein expression of catecholamine (CA)- related genes. Then, I performed molecular engineering to increase TH expression in LUHMES and SH-SY5Y cells. This was sufficient to induce DA production in SH-SY5Y, but not in LUHMES cells, indicating that TH expression is not sufficient to characterize dopaminergic neurons. Therefore I used SH-SY5Y cells overexpressing TH to study substrates for DA production. Upon overexpression of aromatic amino acid decarboxylase (AADC), LUHMES cells produced DA after L-DOPA supplementation. This model was useful to study L-DOPA uptake in LUHMES cells and I showed that L-DOPA is imported via large amino acid transporter (LAT). In conclusion, the expression of TH is not sufficient to obtain a DA-producing cell system and this work opened many and answered some questions about DA metabolism. [less ▲]

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See detailBig Galois image for p-adic families of positive slope automorphic forms
Conti, Andrea UL

Doctoral thesis (2016)

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See detailIP Box Regime im Europäischen Steuerrecht
Schwarz, Paloma Natascha UL

Doctoral thesis (2016)

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See detailDoping, Defects And Solar Cell Performance Of Cu-rich Grown CuInSe2
Bertram, Tobias UL

Doctoral thesis (2016)

Cu-rich grown CuInSe2 thin-film solar cells can be as efficient as Cu-poor ones. However record lab cells and commercial modules are grown exclusively under Cu-poor conditions. While the Cu-rich ... [more ▼]

Cu-rich grown CuInSe2 thin-film solar cells can be as efficient as Cu-poor ones. However record lab cells and commercial modules are grown exclusively under Cu-poor conditions. While the Cu-rich material’s bulk properties show advantages, e.g. higher minority carrier mobilities and quasi-Fermi level splitting - both indicating a superior performance - it also features some inherent problems that led to its widespread dismissal for solar cell use. Two major challenges can be identified that negatively impact the Curich’s performance: a too high doping density and recombination close to the interface. In this work electrical characterisation techniques were employed to investigate the mechanisms that cause the low performance. Capacitance measurements are especially well suited to probe the electrically active defects within the space-charge region. Under a variation of applied DC bias they give insights into the shallow doping density, while frequency and temperature dependent measurements are powerful in revealing deep levels within the bandgap. CuInSe2 samples were produced via a thermal co-evaporation process and subsequently characterized utilizing the aforementioned techniques. The results have been grouped into two partial studies. First the influence of the Se overpressure during growth on the shallow doping and deep defects is investigated and how this impacts solar cell performance. The second study revolves around samples that feature a surface treatment to produce a bilayer structure - a Cu-rich bulk and a Cu-poor interface. It is shown that via a reduction of the Se flux during absorber preparation the doping density can be reduced and while this certainly benefits solar cell efficiency, a high deficit in open-circuit voltage still results in lower performance compared to the Cu-poor devices. Supplementary measurements trace this back to recombination close to the interface. Furthermore a defect signature is identified, that is not present in Cu-poor material. These two results are tied together via the investigation of the surface treated samples, which do not show interface recombination and reach the same high voltage as the Cu-poor samples. The defect signature, normally native to the Cu-rich material, however is not found in the surface treated samples. It is concluded that this deep trap acts as a recombination centre close to the interface. Shifting it towards the bulk via the treatment is then related to the observed increase in voltage. Within this thesis a conclusive picture is derived to unite all measurement results and show the mechanisms that work together and made it possible to produce a high efficient Cu-rich thin-film solar cell. [less ▲]

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See detailAccession Treaties in the EU legal order
Prek, Miro UL

Doctoral thesis (2016)

In the present thesis, it is argued that (1) the Accession Treaties have been used in accordance with their nature and proclaimed objective: they only brought about limited changes to primary law, proper ... [more ▼]

In the present thesis, it is argued that (1) the Accession Treaties have been used in accordance with their nature and proclaimed objective: they only brought about limited changes to primary law, proper to the needs of accession and have not introduced any fundamental changes. The numerous and still growing arrangements that depart from the principle of the application of the acquis in toto on accession do not alter this conclusion. (2) The evolution, especially from the 2004 Accession Treaty onwards and predictable for the future Accession Treaties (e.g. with Turkey), shows a tendency of diversification of that legal instrument by (a) adding new and/or reinforced elements of conditionality, protracted from the pre-accession phase to the membership phase, devising new mechanisms of conditionality and control (general and specific safeguard clauses, monitoring and verification mechanisms, membership postponement clause) and thus (b) contributing to a further differentiation in two respects - as among the Member States and with regard to the core acquis. Such differentiation exists already on the basis of the constitutive treaties (“in-built constitutive treaties induced differentiation”) and is accentuated by the Accession Treaties and their transitional arrangements (“Accession Treaties induced differentiation”). Questions of differentiation acquired another dimension with the introduction of the citizenship of the EU. (3) Finally, negotiations with certain candidate countries will show whether additional innovations are to be expected: a) whether future instruments of accession would be used in order to increase the existing level of differentiation (and protract the pre-accession phase logic well into the membership phase) with the conditionality becoming the most important element of the relations within an enlarged EU and thus paradoxically negating the nature of the integration itself, b) whether they will perhaps be used to bring about more important modifications to the treaties, or c) whether they will go as far as to provide a legal basis for permanent derogations with regard to certain new Member States (as explicitly envisaged, for instance, in the negotiating framework for Turkey). [less ▲]

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See detailTowards harmonization of proteomics methods. Implication for high resolution/accurate mass targeted methods.
Bourmaud, Adèle Gaëlle Annabelle UL

Doctoral thesis (2016)

Mass spectrometry plays a central role in proteomics studies which has allowed its expansion to biomedical research. In an effort to accelerate the understanding of the various aspects of protein biology ... [more ▼]

Mass spectrometry plays a central role in proteomics studies which has allowed its expansion to biomedical research. In an effort to accelerate the understanding of the various aspects of protein biology, the comparison and integration of results across laboratories have gained importance. However, the variety of laboratory-specific protocols, instruments, and data processing methods limits the reliability and reproducibility of the proteomics datasets. The harmonization of LC-MS based proteomics experiments is thus urgently needed to ensure that the workflows used are suitable for the intended purpose of the experiments and that they generate consistent and reproducible results. In a first step towards this harmonization, the critical components of each step of the workflow must be identified. Consolidated sample preparation methods with defined recovery and qualified platforms along with systematic assessment of their performance have to be established. They should ultimately rely on well-defined recommendations and reference materials. Towards these goals, the present project aimed to define, based on current proteomics practices and recent technologies, experimental protocols that will constitute reference methods for the community. The associated results will represent a baseline that can be used to benchmark workflows and platforms, and to conduct routine experiments. A quality control procedure was developed to routinely assess the uniformity of proteomics analyses. The combination of a simple protocol and the addition of reference materials at different stages of the workflow allowed a straightforward monitoring of both sample preparation and LC-MS performance. In addition, as high resolution/accurate mass instruments with fast scanning capabilities turned out to be particularly suited to targeted quantitative experiments, a significant part of the work has consisted in the evaluation of the capabilities offered by such mass spectrometers to promote good practice upon their inception. The methods developed based on these emerging technologies were compared to the existing workflows allowing recommendations to be made for their implementation for fit-for-purpose experiments. [less ▲]

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See detailSoil Fatigue Due To Cyclically Loaded Foundations
Pytlik, Robert Stanislaw UL

Doctoral thesis (2016)

Cyclic loading on civil structures can lead to a reduction of strength of the used materials. A literature study showed that, in contrast to steel structures and material engineering, there are no design ... [more ▼]

Cyclic loading on civil structures can lead to a reduction of strength of the used materials. A literature study showed that, in contrast to steel structures and material engineering, there are no design codes or standards for fatigue of foundations and the surrounding ground masses in terms of shear strength reduction. Scientific efforts to study the fatigue behaviour of geomaterials are mainly focused on strain accumulation, while the reduction of shear strength of geomaterials has not been fully investigated. It has to be mentioned that a number of laboratory investigation have been done and some models have been already proposed for strain accumulation and pore pressure increase which can lead to liquefaction. Laboratory triaxial tests have been performed in order to evaluate the fatigue of soils and rocks by comparing the shear strength parameters obtained in cyclic triaxial tests with the static one. Correlations of fatigue with both, the number of cycles and cyclic stress ratio have been given. In order to apply cyclic movements in a triaxial apparatus, a machine setup and configuration was made. A special program was written in LabVIEW to control the applied stresses and the speed of loading, which allowed simulating the natural loading frequencies. Matlab scripts were also written to reduce the time required for the data processing. Both cohesive and cohesionless geomaterials were tested: artificial gypsum and mortar as cohesive geomaterials, and sedimentary limestone, and different sands, as cohesionless and low-cohesive natural materials. The artificial gypsum, mortar and natural limestone exhibit mostly brittle behaviour, where the crumbled limestone and other sand typical ductile one. All the sands as well as the crumbled limestone were slightly densified before testing therefore; they can be treated as dense sands. The UCS for the crumbled limestone is 0.17 MPa and standard error of estimate σest = 0.021 MPa, where for mortar UCS = 9.11 MPa with σest = 0.18 MPa and for gypsum UCS = 6.02 MPa with standard deviation = 0.53. All triaxial tests were conducted on dry samples in the natural state, without presence of water (no pore pressure). The range of the confining pressure was between 0 MPa and 0.5 MPa. The cyclic tests carried out were typical multiple loading tests with constant displacement ratio up to a certain stress level. The frequency was kept low to allow for precise application of cyclic load and accurate readings. What is more, the frequency of the cyclic loading corresponds to the natural loading of waves and winds. The number of applied cycles was from few cycles up to few hundred thousand (max number of applied cycles was 370 000). Due to the complex behaviour of materials and high scatter of the results, many tests were required. Two different strategies were used to investigate fatigue of geomaterials: 1) the remaining shear strength curve; after a given number of cycles, a final single load test was done until failure in order to measure the remaining shear strength of the sample. 2) the typical S-N curve (Wöhler curves); there is simply a constant loading until failure. The remaining shear strength (or strength reduction) curve has been compared with the standard S-N curve, and is found to be very similar because the cyclic stress ratio has little influence. The cyclic loading on geomaterials, being an assemblage of different sizes and shapes of grains with voids etc., showed different types of effects. Cohesionless materials show a shear strength increase during the cyclic loading, while cohesive ones show a shear strength decrease. For the cohesive materials the assumption was made that the friction angle remains constant; so, the fatigue of geomaterials can be seen as a reduction of the cohesion. In this way, the fatigue of a cohesive geomaterial can be described by a remaining cohesion. The imperfections in the artificial gypsum have a significant impact on the results of the (especially cyclic) strength tests. Therefore another man made materials was used – a mixture of sand and cement (mortar). As the first static test results were very promising, mortar was used in further tests. The cyclic tests, however, presented similar, high scatter of results as for artificial gypsum. An unexpected observation for both materials was a lack of dependency of the remaining shear strength on the cyclic stress ratio. The strain-stress relationship in cyclic loading shows that the fatigue life of the geomaterials can be divided into three stages, just as for creep. The last phase with a fast increase in plastic strains could be an indicator of an incoming failure. The accumulation of strains and increase of internal energy could be good indicators too, but no strong correlation, has been found. Similar to the shear strength, the stiffness changes during cyclic loading; for cohesive materials the stiffness increase, while for cohesionless it decreases. This could help to predict the remaining shear strength of a geomaterial by using a non-destructive method. [less ▲]

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See detailSocio-Technical Aspects of Security Analysis
Huynen, Jean-Louis UL

Doctoral thesis (2016)

This thesis seeks to establish a semi-automatic methodology for security analysis when users are considered part of the system. The thesis explores this challenge, which we refer to as ‘socio-technical ... [more ▼]

This thesis seeks to establish a semi-automatic methodology for security analysis when users are considered part of the system. The thesis explores this challenge, which we refer to as ‘socio-technical security analysis’. We consider that a socio-technical vulnerability is the conjunction of a human behaviour, the factors that foster the occurrence of this behaviour, and a system. Therefore, the aim of the thesis is to investigate which human-related factors should be considered in system security, and how to incorporate these identified factors into an analysis framework. Finding a way to systematically detect, in a system, the socio-technical vulnerabilities that can stem from insecure human behaviours, along with the factors that influence users into engaging in these behaviours is a long journey that we can summarise in three research questions: 1. How can we detect a socio-technical vulnerability in a system? 2. How can we identify in the interactions between a system and its users, the human behaviours that can harm this system’s security? 3. How can we identify the factors that foster human behaviours that are harmful to a system’s security? A review of works that aim at bringing social sciences findings into security analysis reveals that there is no unified way to do it. Identifying the points where users can harm a system’s security, and clarifying what factors can foster an insecure behaviour is a complex matter. Hypotheses can arise about the usability of the system, aspects pertaining to the user or the organisational context but there is no way to find and test them all. Further, there is currently no way to systematically integrate the results regarding hypotheses we tested in a security analysis. Thus, we identify two objectives related to these methodological challenges that this thesis aims at fulfilling in its contributions: 1. What form should a framework that intends to identify harmful behaviours for security, and to investigate the factors that foster their occurrence take? 2. What form should a semi-automatic, or tool-assisted methodology for the security analysis of socio-technical systems take? The thesis provides partial answers to the questions. First it defines a methodological framework called STEAL that provides a common ground for an interdisciplinary approach to security analysis. STEAL supports the interaction between computer scientists and social scientists by providing a common reference model to describe a system with its human and non-human components, potential attacks and defences, and the surrounding context. We validate STEAL in a two experimental studies, showing the role of the context and graphical cues in Wi-Fi networks’ security. Then the thesis complements STEAL with a Root Cause Analysis (RCA) methodology for security inspired from the ones used in safety. This methodology, called S·CREAM aims at being more systematic than the research methods that can be used with STEAL (surveys for instance) and at providing reusable findings for analysing security. To do so, S·CREAM provides a retrospective analysis to identify the factors that can explain the success of past attacks and a methodology to compile these factors in a form that allows for the consideration of their potential effects on a system’s security, given an attacker Threat Model. The thesis also illustrates how we developed a tool—the S·CREAM assistant— that supports the methodology with an extensible knowledge base and computer-supported reasoning. [less ▲]

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See detailLogic and Games of Norms: a Computational Perspective
Sun, Xin UL

Doctoral thesis (2016)

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See detailInfluence of interface conditioning and dopants on Cd-free buffers for Cu(In,Ga)(S,Se)2 solar cells
Hönes Geb. Wiese, Christian UL

Doctoral thesis (2016)

In the search for a non-toxic replacement of the commonly employed CdS buffer layer for Cu(In,Ga)(S,Se)2 (CIGSSe) based solar cells, indium sulfide thin films, deposited via thermal evaporation, and ... [more ▼]

In the search for a non-toxic replacement of the commonly employed CdS buffer layer for Cu(In,Ga)(S,Se)2 (CIGSSe) based solar cells, indium sulfide thin films, deposited via thermal evaporation, and chemical bath deposited (CBD) Zn(O,S) thin films are promising materials. However, while both materials have already been successfully utilized in highly efficient cells, solar cells with both materials usually need an ill-defined post-treatment step in order to reach maximum efficiencies, putting them at a disadvantage for mass production. In this thesis the influence of interface conditioning and dopants on the need for post-treatments is investigated for both materials, giving new insights into the underlying mechanisms and paving the way for solar cells with higher initial efficiencies. First, CIGSSe solar cells with In2S3 thin film buffer layers, deposited by thermal evaporation, are presented in chapter 3. The distinctive improvement of these buffer layers upon annealing of the completed solar cell and the change of this annealing behavior when the CIGSSe surface is treated with wet-chemical means prior to buffer layer deposition is investigated. Additional model simulations lead to a two-part explanation for the observed effects, involving a reduction of interface recombination, and the removal of a highly p-doped CIGSSe surface layer. chapter 4 introduces a novel, fast process for the deposition of Zn(O,S) buffer layers on submodule sized substrates. The resulting solar cell characteristics and the effects of annealing and prolonged illumination are discussed within the framework of theoretical considerations involving an electronic barrier for generated charge carriers. The most important influences on such an electronic barrier are investigated by model simulations and an experimental approach to each parameter. This leads to an improved window layer deposition process, absorber optimization, and intentional buffer layer doping, all reducing the electronic barrier and therefore the necessity for post-treatments to some extent. The energetic barrier discussed above may be avoided altogether by effective interface engineering. Therefore, the controlled incorporation of indium as an additional cation into CBD-Zn(O,S) buffer layers by means of a newly developed alkaline chemical bath deposition process is presented in chapter 5. With increasing amount of incorporated indium, the energetic barrier in the conduction band can be reduced. This is quantitatively assessed by a combination of photoelectron spectroscopy measurements and the determination of the buffer layer's optical band gap. This barrier lowering leads to less distorted current--voltage characteristics and efficiencies above 14 %, comparable to CdS reference cells, without extensive light-soaking. [less ▲]

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See detailRepräsentationen der Kaiserin Elisabeth von Österreich nach dem Ende des Habsburgerreiches. Eine struktur-funktionale Untersuchung mythisierender Filmdarstellungen
Karczmarzyk, Nicole UL

Doctoral thesis (2016)

By tracing the process of the evolving myth surrounding the empress Elisabeth of Austria since her death one would very likely find an almost continuous sinusoidal curve as a result. The aim of the thesis ... [more ▼]

By tracing the process of the evolving myth surrounding the empress Elisabeth of Austria since her death one would very likely find an almost continuous sinusoidal curve as a result. The aim of the thesis is to explore the question which mediating sociopolitical functions the myth fullfils and where its value lies within the national and historical myth systems (the ones of Austria and also Prussia/Germany) by analysing audio-visual media, especially films. Since the representations of the Empress during the 20. century have been mainly manifested within popular culture, printed media, like e.g. newspapers, magazines, biograhies will also be considered for the analysis as well as theatrical plays like operas and musical comedies. The thesis stresses that the myth of Empress Elizabeth of Austria can be seen as a set of essential kernels, in structuralism theory called ‚mythemes’, that can constantly get reassembled and re-told. The mythemes and the actualizations of the myth itself are to be elaborated as well as its different cultural functionalisations at different times by diachronical and a synchronical readings. The thesis is trying to fill the gap of the frequently stated absence of female figures within the field of myth research and points out functions of a contemporary myth and its different appearances. Beyond that those procedures and strategies of media will be addressed that lead a long constituted myth into serving as a collective character or figure which can continously be applicated into new thematic contexts. The main proposition of the thesis is that the representations of Empress Elizabeth of Austria during the 20th century have gotten adjusted to the sociocultural contexts of the particular time they have appeared in. The character of the Empress has therefore been utilized as a carrier for different ideologies, e.g. the idea of the multiethnic state of the Habsburgian Empire, as well as the national socialists idea of a the ethnic community, the ‚Volksgemeinschaft’. The representations also adjust to altering female stererotypes and even role models like e.g. the ideal wife or in the ending 20th century the progressive feminist. [less ▲]

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See detailAutomated Security Testing of Web-Based Systems Against SQL Injection Attacks
Appelt, Dennis UL

Doctoral thesis (2016)

Injection vulnerabilities, such as SQL injection (SQLi), are ranked amongst the most dangerous types of vulnerabilities. Despite having received much attention from academia and practitioners, the ... [more ▼]

Injection vulnerabilities, such as SQL injection (SQLi), are ranked amongst the most dangerous types of vulnerabilities. Despite having received much attention from academia and practitioners, the prevalence of SQLi is common and the impact of their successful exploitation is severe. In this dissertation, we propose several security testing approaches that evaluate web applications and services for vulnerabilities and common IT infrastructure components such as for their resilience against attacks. Each of the presented approaches covers a different aspect of security testing, e.g. the generation of test cases or the definition of test oracles, and in combination they provide a holistic approach. The work presented in this dissertation was conducted in collaboration with SIX Payment Services (formerly CETREL S.A.). SIX Payment Services is a leading provider of financial services in the area of payment processing, e.g. issuing of credit and debit cards, settlement of card transactions, online payments, and point-of-sale payment terminals. We analyse the challenges SIX is facing in security testing and base our testing approaches on assumptions inferred from our findings. Specifically, the devised testing approaches are automated, applicable in black box testing scenarios, able to assess and bypass Web Application Firewalls (WAF), and use an accurate test oracle. The devised testing approaches are evaluated with SIX’ IT platform, which consists of various web services that process several thousand financial transactions daily. The main research contributions in this dissertation are: - An assessment of the impact of Web Application Firewalls and Database Intrusion Detection Systems on the accuracy of SQLi testing. - An input mutation technique that can generate a diverse set of test cases. We propose a set of mutation operators that are specifically designed to increase the likelihood of generating successful attacks. - A testing technique that assesses the attack detection capabilities of a Web Application Firewall (WAF) by systematically generating attacks that try to bypass it. - An approach that increases the attack detection capabilities of a WAF by inferring a filter rule from a set of bypassing attacks. The inferred filter rule can be added to the WAF’s rule set to prevent attacks from bypassing. - An automated test oracle that is designed to meet the specific requirements of testing in an industrial context and that is independent of any specific test case generation technique. [less ▲]

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See detailL’expérience utilisateur : Relations entre utilisabilité et esthétique, affects et comportements dans une tâche de recherche d’information sur tablettes numériques
Pere, Maxime UL

Bachelor/master dissertation (2016)

While the study of human-machine interactions is fairly well established regarding usability dimensions, the approach of the user experience, more recent, incorporates new dimensions in order to bring to ... [more ▼]

While the study of human-machine interactions is fairly well established regarding usability dimensions, the approach of the user experience, more recent, incorporates new dimensions in order to bring to light on these interactions. This work takes part in this approach and aims to clarify the relationship between a non-functional quality and a functional quality of a system, the main effect of these qualities on the affects experienced during the interaction with the system and finally the effect of the system qualities on behaviours. A research information task on 4 Websites corresponding to both crossed variables, aesthetics (high vs low) and usability (high vs low), should allow us to explore these questions through self-reports measures and behavioural recording. In addition, we attempt to identify relevant indicators which have not been used much yet. This study is run on touch tablet computers on Windows systems. [less ▲]

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See detailAspekte der Mehrsprachigkeit in Luxemburg. Positionen, Funktionen und Bewertungen der deutschen Sprache. Eine diskursanalytische Untersuchung (1983-2015).
Scheer, Fabienne UL

Doctoral thesis (2016)

The thesis provides a broad insight into the current position of the German language in Luxembourg. It describes the linguistic knowledge and behavior of the different speech groups, that are acting in ... [more ▼]

The thesis provides a broad insight into the current position of the German language in Luxembourg. It describes the linguistic knowledge and behavior of the different speech groups, that are acting in the domains "education", "mass media", "immigration and integration", "xenophobic discourse", "language policy", "language and literature", "PR" and "languages for publicity" and shows how the dominant, luxembourgish, speech group is adapting linguistically to the evolution of the society. The conclusions are based on a corpus of 835 press articles, on interviews with experts from the different fields of the society and on further material (statistics, parlamentiary debates, administrative writings, examples of german exercises written by pupils ...). [less ▲]

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See detailTopology and Parameter Estimation in Power Systems Though Inverter Based Broadband Stimulations
Neshvad, Surena UL

Doctoral thesis (2016)

During the last decade, a substantial growth in renewable, distributed energy production has been observed in industrial countries. This phenomenon, coupled with the adoption of open energy markets has ... [more ▼]

During the last decade, a substantial growth in renewable, distributed energy production has been observed in industrial countries. This phenomenon, coupled with the adoption of open energy markets has signi cantly complicated the power ows on the distribution network, requiring advanced and intelligent system monitoring in order to optimize the e ciency, quality and reliability of the system. This thesis proposes a solution several power network challenges encountered with increasing Distributed Generation (DG) penetration. The three problems that are addressed are islanding detection, online transmission line parameter identi cation and system topology identi cation. These tasks are performed by requesting the DGs to provide ancillary services to the network operator. A novel and intelligent method has been proposed for reprogramming the DGs Pulse Width Modulator, requesting each DG to inject a uniquely coded Pseudo-Random Binary Sequence along with the fundamental. Islanding detection is obtained by measuring the equivalent Thevenin impedance at the inverters Point of Common Coupling, while system characterization is obtained by measuring the induced current frequencies at various locations in the grid. To process and evaluate the measured signals, a novelWeighed Least-Squares aggregation method is developed, through which measurements are combined and correlated in order to obtain an accurate snapshot of the power network parameters. [less ▲]

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See detailDynamics of viscoelastic colloidal suspensions
Dannert, Rick UL

Doctoral thesis (2016)

The influence of different types of nanoparticles on the dynamics of glass forming matrices has been studied by small oscillatory shear rheology. Experimental measurements reveal that besides the glass ... [more ▼]

The influence of different types of nanoparticles on the dynamics of glass forming matrices has been studied by small oscillatory shear rheology. Experimental measurements reveal that besides the glass transition process of the matrix an additional relaxation process occurs in presence of nanoparticles. The latter is identified as the macroscopic signature of the microscopic temporal fluctuations of the intrinsic stress and is called Brownian relaxation. Besides the fact that Brownian relaxation has so far not been observed in colloidal suspensions with a matrix exhibiting viscoelastic behaviour in the frequency range of the experimental probe, the study reveals another important feature to be highlighted: the evolution of the Brownian relaxation times depends non-monotonously on the filler concentration. This finding challenges the use of the classical Peclet-time as a characteristic timescale for Brownian relaxation. Literature defines the Peclet-time as the specific time needed by a particle to cover –via self-diffusion- a distance comparable to its own size. As a main result it will be shown that after replacing the particle size which is relevant for the Peclet time by the mean interparticle distance depending on the filler content the non-monotonic evolution of the relaxation times can be fully described. Moreover, the introduction of the new characteristic length scale allows to include data from literature into the phenomenological description. [less ▲]

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See detailSingularités orbifoldes de la variété des caractères
Guerin, Clément UL

Doctoral thesis (2016)

In this thesis, we want to understand some singularities in the character variety. In a first chapter, we justify that the characters of irreducible representations from a Fuchsian group to a complex semi ... [more ▼]

In this thesis, we want to understand some singularities in the character variety. In a first chapter, we justify that the characters of irreducible representations from a Fuchsian group to a complex semi-simple Lie group is an orbifold. The orbifold locus is, then, the characters of bad representations. In the second chapter, we focus on the case where the Lie group is PSL(p,C) with p a prime number. In particular we give an explicit description of this locus. In the third and fourth chapter, we describe the isotropy groups (i.e. the centralizers of bad subgroups) arising in the cases when the Lie group is a quotient SL(n,C) (third chapter) and when the Lie group is a quotient of Spin(n,C) in the fourth chapter. [less ▲]

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See detailTopic Identification Considering Word Order by Using Markov Chains
Kampas, Dimitrios UL

Doctoral thesis (2016)

Automated topic identification of text has gained a significant attention since a vast amount of documents in digital forms are widespread and continuously increasing. Probabilistic topic models are a ... [more ▼]

Automated topic identification of text has gained a significant attention since a vast amount of documents in digital forms are widespread and continuously increasing. Probabilistic topic models are a family of statistical methods that unveil the latent structure of the documents defining the model that generates the text a priori. They infer about the topic(s) of a document considering the bag-of-words assumption, which is unrealistic considering the sophisticated structure of the language. The result of such a simplification is the extraction of topics that are vague in terms of their interpretability since they disregard any relations among the words that may settle word ambiguity. Topic models miss significant structural information inherent in the word order of a document. In this thesis we introduce a novel stochastic topic identifier for text data that addresses the above shortcomings. The primary motivation of this work is initiated by the assertion that word order reveals text semantics in a human-like way. Our approach recognizes an on-topic document trained solely on the experience of an on-class corpus. It incorporates the word order in terms of word groups to deal with data sparsity of conventional n-gram language models that usually require a large volume of training data. Markov chains hereby provide a reliable potential to capture short and long range language dependencies for topic identification. Words are deterministically associated with classes to improve the probability estimates of the infrequent ones. We demonstrate our approach and motivate its eligibility on several datasets of different domains and languages. Moreover, we present a pioneering work by introducing a hypothesis testing experiment that strengthens the claim that word order is a significant factor for topic identification. Stochastic topic identifiers are a promising initiative for building more sophisticated topic identification systems in the future. [less ▲]

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See detailEnergy minimising multi-crack growth in linear-elastic materials using the extended finite element method with application to Smart-CutTM silicon wafer splitting
Sutula, Danas UL

Doctoral thesis (2016)

We investigate multiple crack evolution under quasi-static conditions in an isotropic linear-elastic solid based on the principle of minimum total energy, i.e. the sum of the potential and fracture ... [more ▼]

We investigate multiple crack evolution under quasi-static conditions in an isotropic linear-elastic solid based on the principle of minimum total energy, i.e. the sum of the potential and fracture energies, which stems directly from the Griffith’s theory of cracks. The technique, which has been implemented within the extended finite element method, enables minimisation of the total energy of the mechanical system with respect to the crack extension directions. This is achieved by finding the orientations of the discrete crack-tip extensions that yield vanishing rotational energy release rates about their roots. In addition, the proposed energy minimisation technique can be used to resolve competing crack growth problems. Comparisons of the fracture paths obtained by the maximum tension (hoop-stress) criterion and the energy minimisation approach via a multitude of numerical case studies show that both criteria converge to virtually the same fracture solutions albeit from opposite directions. In other words, it is found that the converged fracture path lies in between those obtained by each criterion on coarser numerical discretisations. Upon further investigation of the energy minimisation approach within the discrete framework, a modified crack growth direction criterion is proposed that assumes the average direction of the directions obtained by the maximum hoop stress and the minimum energy criteria. The numerical results show significant improvements in accuracy (especially on coarse discretisations) and convergence rates of the fracture paths. The XFEM implementation is subsequently applied to model an industry relevant problem of silicon wafer cutting based on the physical process of Smart-CutTM technology where wafer splitting is the result of the coalescence of multiple pressure-driven micro-crack growth within a narrow layer of the prevailing micro-crack distribution. A parametric study is carried out to assess the influence of some of the Smart-CutTM process parameters on the post-split fracture surface roughness. The parameters that have been investigated, include: mean depth of micro-crack distribution, distribution of micro-cracks about the mean depth, damage (isotropic) in the region of micro-crack distribution, and the influence of the depth of the buried-oxide layer (a layer of reduced stiffness) beneath the micro-crack distribution. Numerical results agree acceptably well with experimental observations. [less ▲]

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See detailInstitutionalisierung der Naturwissenschaften in Preußen als Investition in die Zukunft. Die Friedrich-Wilhelms-Universität in Bonn und die Leopoldina (1818-1830)
Röther, Bastian UL

Doctoral thesis (2016)

Analysing the genesis of institutions of scientific research and information in Prussia using the university location of Bonn as an example 1818 – 1830 // The 19th century represented a profound turning ... [more ▼]

Analysing the genesis of institutions of scientific research and information in Prussia using the university location of Bonn as an example 1818 – 1830 // The 19th century represented a profound turning point in the development of the sciences that was characterized by an enormous surge in development and the emergence of modern scientific disciplines. In the natural sciences, this development was evident by their gradual emancipation from the medical faculty and an increasing differentiation and scientification of the curriculum. During this period of reform in the early 19th century, Prussia faced the task of reforming its traditional education system and transferring this to its provinces in the Rhineland and in Westphalia. These efforts to create an educational state centred around the Central University in Berlin, founded in 1810, the University of Breslau and, above all, Friedrich Wilhelm University, which was founded on the Rhine in 1818 and was one of Prussia’s most important provincial universities. The Imperial Leopoldina Carolina German Academy of Natural Scientists was simultaneously moved, creating conditions that were on par with Prussia’s capital. By 1818, Bonn had two important scientific institutions at its disposal, one of which had an explicit medical-scientific connotation. The institutional collaboration that arose between the academy and the university therefore promised to give the natural sciences an opportunity to receive special support as explicitly stipulated in the development concept drawn up for the university by the head of the department, Altenstein. The fact that the scientific academies fell within the jurisdiction of the Ministry of Culture appeared particularly auspicious. Altenstein’s concept of emancipation and promotion of the natural sciences included a high degree of integration of the applied sciences. One question that had received little attention was how this concentration of institutions impacted the development of the service and research institutions of the natural sciences and to what extent Berlin was able to model this tighter relationship between the institutions. Older papers have placed the development of the individual scientific subjects during this phase of the university’s foundation in a much more negative light, referring time and again to the way in which Bonn’s representatives of natural philosophy hampered this development. In contrast, more recent research findings recognize the tremendously important role the natural sciences played in the ministerial concept of 1818 and the resulting extensive and excellent conditions for these subjects which were modelled after Berlin. As a result, they represent a much more differentiated picture of the foundation years. A source-based and cross-subject study that also scrutinized the role of the Academy of Sciences Leopoldina remained a desideratum. Moving the academy has generally been regarded as extremely necessary for the further development of Bonn as a location of science; its collections and facilities signifying an important foundation for good institutional development. The basis of this paper was the official correspondence between Bonn’s scientists and Altenstein, the Prussian department head, as well as Prussia’s State Chancellor Hardenberg. It focuses on the key aspects of the analysis of appointment policy, organisation of the institutes, reform efforts and the relationship to extramural institutions. Of great importance is the exchange of letters, edited as part of a Leopoldina project, between Altenstein and the director of the botanical garden in Bonn, Christian Gottfried Nees von Esenbeck who, as president of the Leopoldina, was critically important. The analysis includes the facilities of these natural sciences at the university, e.g. the chemical laboratory and the observatory, as well as the collections and institutes for natural history subjects, like botany, zoology and minerology, and the Natural History Museum and the Botanical Gardens. Furthermore, the paper looks at the university’s relationship to societies organised outside the university, in particular the Leopoldina, as well as the Niederrheinischen Gesellschaft für Natur- und Heilkunde (Lower Rhine Society for Natural History and Medical Studies), which was founded in 1818, and Verein zur Beförderung der Naturstudien (the Society for Promoting the Study of Nature). Investigations have revealed that the culture minister’s ideals to broadly support the sciences and their practical application during the university’s phase of establishment extended far beyond the realm of financial possibilities. Nevertheless, it was possible to establish some excellently equipped institutes in Bonn. The already widely developed plans to incorporate practice-oriented education, however, could not be achieved in these initial years. These locational conditions, established on the basis of political and financial necessity, are reflected in the statistics on the frequency and attendance of lectures, analysed for the first time for the natural sciences in Bonn. Despite the formal separation of the natural sciences from the medical faculty, the physicians were integral to the success of the introductory lectures. On the other hand, from a statistical perspective, these special events are characterised by a high failure rate across all subjects due to a lack of participants. This particularly affected the lectures on natural philosophy which were accepted to a lesser degree by the students during the period under investigation. The general reproach, based on Justus Liebig’s philippic on “The State of Chemistry in Prussia” from 1840, that natural philosophy had hampered development, cannot be concretely substantiated for Bonn. Unlike in Berlin, which had better locational conditions, during these foundation years, Bonn lacked grammar school leavers and university freshmen who were prepared for studying the sciences and who could adequately take advantage of the good basic conditions established in Bonn. The complaints from the instructors in Bonn about the students’ low level of education quickly led to various reform projects that targeted grammar school education and which were almost entirely unknown to research. The Seminar für die gesammten Naturwissenschaften (Seminar of General Sciences), established in 1825 should be mentioned first and foremost. It was the first of its kind in Germany to teach natural sciences as part of a cross-discipline education. Surprisingly, moving the German Academy of Sciences Leopoldina to Bonn played an insignificant role in the development of the scientific location. Conditions can hardly be compared to those in the capital. Ultimately the academy’s institutions proved to be insufficient in supporting the establishment of modern service institutes for the natural sciences. The locational advantage was not exploited in the scientific practice of the natural science and medical disciplines. Thanks to Prussian subsidies, the Leopoldina was able to weather an existential crisis at the end of the 19th century in Bonn. Profound structural reforms were postponed by the academy’s leadership indicating the society’s need to consolidate. With its only main task being the publishing of the journal Nova acta, the academy was punching far below its weight. Using Prussia’s provincial university in Bonn as an example, this paper reveals the extensive efforts made by the education reformers to provide an excellent institutional basis for the young scientific disciplines. The opportunities created in the years when the university was being established could only be utilised by a handful of students due to a lack of scientific schooling, particularly since a link to practical and scientific educational concepts could not be financed. The service institutions therefore remained a promise for a future based on scientific research and teaching that wasn’t to begin in Prussia’s Rhineland until the second half of the 19th century. [less ▲]

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See detailTRANSMISSION OPTIMIZATION FOR HIGH THROUGHPUT SATELLITE SYSTEMS
Gharanjik, Ahmad UL

Doctoral thesis (2016)

Demands on broadband data service are increasing dramatically each year. Following terrestrial trends, satellite communication systems have moved from the traditional TV broadcasting to provide ... [more ▼]

Demands on broadband data service are increasing dramatically each year. Following terrestrial trends, satellite communication systems have moved from the traditional TV broadcasting to provide interactive broadband services even to urban users. While cellular and land-line networks are mainly designed to deliver broadband services to metropolitan and large urban centers, satellite based solutions have the advantage of covering these demands over a wide geography including rural and remote users. However, to stay competitive with economical terrestrial solutions, it is necessary to reduce the cost per transmitted bit by increasing the capacity of the satellite systems. The objective of this thesis is to design and develop techniques capable of enhancing the capacity of next generation high throughput satellite systems. Specifically, the thesis focuses on three main topics: 1) Q/V band feeder link design, 2) robust precoding design for multibeam satellite systems, and 3) developing techniques for tackling related optimization problems. Design of high bandwidth and reliable feeder links is central towards provisioning new services on the user link of a multibeam SatCom system. Towards this, utilization of the Q/V band and an exploitation of multiple gateway as a transmit diversity measure for overcoming severe propagation effects are being considered. In this context, the thesis deals with the design of a feeder link comprising N + P gateways (N active and P redundant gateways). Towards satisfying the desired availability, a novel switching scheme is analyzed and practical aspects such as prediction based switching and switching rate are discussed. Building on this result, an analysis for the N + P scenario leading to a quantification of the end-to-end performance is provided. On the other hand, frequency reuse in multibeam satellite systems along with precoding techniques can increase the capacity at the user link. Similar to terrestrial communication channels, satellite based communication channels are time-varying and for typical precoding applications, the transmitter needs to know the channel state information (CSI) of the downlink channel. Due to fluctuations of the phase components, the channel is time-varying resulting in outdated CSI at the transmitter because of the long round trip delay. This thesis studies a robust precoder design framework considering requirements on availability and average signal to interference and noise ratio (SINR). Probabilistic and expectation based approaches are used to formulate the design criteria which are solved using convex optimization tools. The performance of the resulting precoder is evaluated through extensive simulations. Although a satellite channel is considered, the presented analysis is valid for any vector channel with phase uncertainty. In general, the precoder design problem can be cast as power minimization problem or max-min fairness problem depending on the objectives and requirements of design. The power minimization problem can typically be formulated as a non-convex quadratically constrained quadratic programming (QCQP) problem and the max-min fairness problem as a fractional quadratic program. These problems are known to be NP-hard in general. In this thesis, the original design problem is transformed to an unconstrained optimizationproblem using the specialized penalty terms. The efficient iterative optimization frameworks are proposed based on a separate optimization of the penalized objective function over its partition of variables at each iteration. Various aspects of the proposed approach including performance of the algorithm and its implementation complexity are studied. This thesis is made under joint supervision agreement between KTH Royal Institute of Technology, School of Electrical Engineering, Stockholm, Sweden and University of Luxembourg, Luxembourg. [less ▲]

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See detailFunctional characterization of novel RhoT1 variants, which are associated with Parkinson's disease.
Grossmann, Dajana UL

Doctoral thesis (2016)

Parkinson’s disease (PD) is a common neurodegenerative disease affecting up to 2 % of the population older than 65 years. Most PD cases are sporadic with unknown cause, and about 10 % are familial ... [more ▼]

Parkinson’s disease (PD) is a common neurodegenerative disease affecting up to 2 % of the population older than 65 years. Most PD cases are sporadic with unknown cause, and about 10 % are familial inherited. PD is a progressive neurodegenerative disease characterized by loss of predominantly dopaminergic neurons, leading to typical symptoms like rigidity and tremor. Commonly involved pathogenic pathways are linked to mitochondrial dysfunction, e.g. increased oxidative stress, disruption of calcium homeostasis, decreased energy supply and mitochondrial-controlled apoptosis. The mitochondrial outer membrane protein Miro1 is important for mitochondrial distribution, quality control and maintenance. To date Miro1 is not established as risk factor for PD. Using a comprehensive mutation screening of RhoT1 in German PD patients we dissected the role of the first PD-associated mutations in RhoT1, the gene encoding for Miro1. Three mutations in RhoT1 have been identified in three PD patients with positive family history for PD. For analysis of mitochondrial phenotypes patient-derived fibroblasts from two of the three patients were available. As independent cell model served the neuroblastoma cell line M17 with stable knockdown of endogenous RhoT1 and transiently overexpression of the RhoT1 mutant variants. Investigation of yeast with knockout of endogenous Gem1 (the yeast orthologue of Miro1) and overexpression of mutant Gem1 revealed that growth on non-fermentable carbon source was impaired. These findings suggest that Miro1-mutant1 is a loss of function mutation. Interestingly, the Miro1 protein amount was significantly reduced in Miro1-mutant1 and Miro1-mutant2 fibroblast lines compared to controls. Functional analysis revealed that mitochondrial mass was decreased in Miro1-mutant2, but not in Miro1-mutant1 fibroblasts, whereas mitochondrial biogenesis was increased in Miro1-mutant2 fibroblasts, as indicated by elevation of PGC1α. A similar phenotype with reduction of mitochondrial mass was also observed in M17 cells overexpressing Miro1-mutant1 or Miro1-mutant2. Additionally, spare respiratory capacity was reduced in Miro1-mutant1 fibroblasts compared to Ctrl 1 fibroblasts. In contrast, Miro1-mutant2 fibroblasts showed increased respiratory activity compared to Ctrl 1, despite citrate synthase activity was significantly reduced. Both alterations of respiratory activity lead to mitochondrial membrane hyperpolarization in Miro1-mutant1 and Miro1-mutant2 fibroblasts, a phenotype which was also found in M17 cells with knockdown of RhoT1. Both Miro1 mutant fibroblasts lines displayed different problems with cytosolic calcium buffering: in Miro1-mutant1 fibroblasts histamine treatment increased cytosolic calcium concentration significantly compared to Ctrl 1 fibroblasts, indicating that calcium homeostasis was impaired, whereas in Miro1-mutant2 fibroblasts the buffering capacity for cytosolic calcium was impaired. The results indicate that mutations in Miro1 cause significant mitochondrial dysfunction, which are likely contributing to neurodegeneration in PD and underline the importance of Miro1 for mitochondrial maintenance. [less ▲]

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See detail„Grow into a happy future“ The development of abortion law in the German Democratic Republic and its ideological and practical implications (1945 - 1972)
Wingerter, Elisabeth UL

Bachelor/master dissertation (2016)

The master's thesis aims at exploring the laws regulating abortion and reproduction in the GDR until its legalization in 1972. These laws, their impact and mediatization are put into a comparative ... [more ▼]

The master's thesis aims at exploring the laws regulating abortion and reproduction in the GDR until its legalization in 1972. These laws, their impact and mediatization are put into a comparative perspective with the situation in the Soviet Union. The thesis further explores how ideologically charged explanations were used to legitimize abortion laws and the discrepancy between the USSR and the GDR in terms of legalization. [less ▲]

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See detailSIGNAL PROCESSING FOR PHYSICAL LAYER SECURITY WITH APPLICATION IN SATELLITE COMMUNICATIONS
Kalantari, Ashkan UL

Doctoral thesis (2016)

Wireless broadcast allows widespread and easy information transfer. However, it may expose the information to unintended receivers, which could include eavesdroppers. As a solution, cryptography at the ... [more ▼]

Wireless broadcast allows widespread and easy information transfer. However, it may expose the information to unintended receivers, which could include eavesdroppers. As a solution, cryptography at the higher network levels has been used to encrypt and protect data. Cryptography relies on the fact that the computational power of the adversary is not enough to break the encryption. However, due to increasing computing power, the adversary power also increases. To further strengthen the security and complement the encryption, the concept of physical layer security has been introduced and surged an enormous amount of research. Widely speaking, the research in physical layer security can be divided into two directions: the information-theoretic and signal processing paradigms. This thesis starts with an overview of the physical layer security literature and continues with the contributions which are divided into the two following parts. In the first part, we investigate the information-theoretic secrecy rate. In the first scenario, we study the confidentiality of a bidirectional satellite network consisting of two mobile users who exchange two messages via a multibeam satellite using the XOR network coding protocol. We maximize the sum secrecy rate by designing the optimal beamforming vector along with optimizing the return and forward link time allocation. In the second scenario, we study the effect of interference on the secrecy rate. We investigate the secrecy rate in a two-user interference network where one of the users, namely user 1, requires to establish a confidential connection. User 1 wants to prevent an unintended user of the network to decode its transmission. User 1 has to adjust its transmission power such that its secrecy rate is maximized while the quality of service at the destination of the other user, user 2, is satisfied. We obtain closed-form solutions for optimal joint power control. In the third scenario, we study secrecy rate over power ratio, namely ``secrecy energy efficiency''. We design the optimal beamformer for a multiple-input single-output system with and without considering the minimum required secrecy rate at the destination. In the second part, we follow the signal processing paradigm to improve the security. We employ the directional modulation concept to enhance the security of a multi-user multiple-input multiple-output communication system in the presence of a multi-antenna eavesdropper. Enhancing the security is accomplished by increasing the symbol error rate at the eavesdropper without the eavesdropper's CSI. We show that when the eavesdropper has less antennas than the users, regardless of the received signal SNR, it cannot recover any useful information; in addition, it has to go through extra noise enhancing processes to estimate the symbols when it has more antennas than the users. Finally, we summarize the conclusions and discuss the promising research directions in the physical layer security. [less ▲]

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See detailModel-Based Test Automation Strategies for Data Processing Systems
Di Nardo, Daniel UL

Doctoral thesis (2016)

Data processing software is an essential component of systems that aggregate and analyse real-world data, thereby enabling automated interaction between such systems and the real world. In data processing ... [more ▼]

Data processing software is an essential component of systems that aggregate and analyse real-world data, thereby enabling automated interaction between such systems and the real world. In data processing systems, inputs are often big and complex files that have a well-defined structure, and that often have dependencies between several of their fields. Testing of data processing systems is complex. Software engineers, in charge of testing these systems, have to handcraft complex data files of nontrivial size, while ensuring compliance with the multiple constraints to prevent the generation of trivially invalid inputs. In addition, assessing test results often means analysing complex output and log data. Complex inputs pose a challenge for the adoption of automated test data generation techniques; the adopted techniques should be able to deal with the generation of a nontrivial number of data items having complex nested structures while preserving the constraints between data fields. An additional challenge regards the automated validation of execution results. To address the challenges of testing data processing systems, this dissertation presents a set of approaches based on data modelling and data mutation to automate testing. We propose a modelling methodology that captures the input and output data and the dependencies between them by using Unified Modeling Language (UML) class diagrams and constraints expressed in the Object Constraint Language (OCL). The UML class diagram captures the structure of the data, while the OCL constraints formally describe the interactions and associations between the data fields within the different subcomponents. The work of this dissertation was motived by the testing needs of an industrial satellite Data Acquisition (DAQ) system; this system is the subject of the empirical studies used within this dissertation to demonstrate the application and suitability of the approaches that we propose. We present four model-driven approaches that address the challenges of automatically testing data processing systems. These approaches are supported by the data models generated according to our modelling methodology. The results of an empirical evaluation show that the application of the modelling methodology is scalable as the size of the model and constraints was manageable for the subject system. The first approach is a technique for the automated validation of test inputs and oracles; an empirical evaluation shows that the approach is scalable as the input and oracle validation process executed within reasonable times on real input files. The second approach is a model-based technique that automatically generates faulty test inputs for the purpose of robustness testing, by relying upon generic mutation operators that alter data collected in the field; an empirical evaluation shows that our automated approach achieves slightly better instruction coverage than the manual testing taking place in practice. The third approach is an evolutionary algorithm to automate the robustness testing of data processing systems through optimised test suites; the empirical results obtained by applying our search-based testing approach show that it outperforms approaches based on fault coverage and random generation: higher coverage is achieved with smaller test suites. Finally, the fourth approach is an automated, model-based approach that reuses field data to generate test inputs that fit new data requirements for the purpose of testing data processing systems; the empirical evaluation shows that the input generation algorithm based on model slicing and constraint solving scales in the presence of complex data structures. [less ▲]

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See detailRegional Continental Water Storage Variations Inferred from Three-dimensional GPS Coordinates Time Series
Wang, Lin UL

Doctoral thesis (2016)

Recent advances in space geodetic techniques (including but is not limited to, Global Navigation Satellite System, GNSS, Very-long-baseline interferometry, VLBI) allow us to observe changes in continental ... [more ▼]

Recent advances in space geodetic techniques (including but is not limited to, Global Navigation Satellite System, GNSS, Very-long-baseline interferometry, VLBI) allow us to observe changes in continental water storage (CWS) depending on the extent and the amplitude of the load. Among the geodetic techniques, GPS is the most common observational tool because of its global distribution. GPS observations are used for many fields of studies, including seismology and tectonics. This thesis presents a method to obtain regional changes in continental water storage by inverting the three-dimensional GPS time series. The error sources from a regional study are studied first. In theory, the surface motions from each GPS station are caused by loads acting over the entire surface of the Earth. As we are only interested in the changing water storage in a particular basin, the loading signal from the far field, outside the region of interest, must be accounted for. From our simulation studies, we conclude that the mass changes locate outside of the study region cannot be neglected. We find that the coverage of the area needs to extend to about 20 degrees (about 20 000 km) of the basin center for a regional study. The second concern is the GPS time series. We find discrepancies over the globe between GPS observed displacements and forward modelled displacements using models of water storage. At annual periods, the thermal expansion of the GPS monuments and underlying bedrock, atmospheric loading, and the draconitic signal if not accounted for will introduce an error into the inversion. These errors may contribute to the disagreement between our forward modelled and observed ground motions. For 88% of the stations analyzed, we are able to reduce the WRMS on the GPS vertical time series by removing the modelled displacements using estimates CWS loading obtained from WaterGAP. We conclude that the most likely cause of the discrepancies come from the GPS observations themselves. Due to the observed discrepancy, we find that the uncertainties of the GPS time series should be re-estimated in any inversion study. Finally, we determine monthly CWS variations from GPS three-dimensional coordinate time series for the major river basins in Europe and North America. The results at the basin scale are validated against GRACE and hydrological models, the correlation between inferred CWS and GRACE or models are close to 0.9 and WRMSR are as high as 50% for some basins. We also demonstrate that the relative contributions of the GPS horizontal coordinates are about one third those of the vertical signals. We prove that by including the horizontal coordinates in the inversion that we are able to improve the inversion results. [less ▲]

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See detailConscience du temps, sentiment de passage du temps: une approche métacognitive de la perception du temps
Lamotte, Mathilde UL

Doctoral thesis (2016)

Metacognition concerns both individuals' knowledge about their cognitive functioning and the processes that regulate them (Koriat, 2007). The study of the perception of time showed that many factors cause ... [more ▼]

Metacognition concerns both individuals' knowledge about their cognitive functioning and the processes that regulate them (Koriat, 2007). The study of the perception of time showed that many factors cause temporal distortions, including, for example, attention or feedback. The purpose of this work is thus to propose an integrative model of metacognition of time perception; i.e. to integrate data based on conventional research on the perception of time in a metacognitive model (Nelson and Narens 1990). Our first question was to verify the existence of knowledge about the perception of time, especially on the factors responsible for temporal distortions. The three experiments of our first study led us to create and validate the Metacognitive Questionnaire on Time (MQT). The latter consists of 24 items that highlights the existence of knowledge, more reliable for oneself (subscale Self, 12 items) than for others (subscale Others, 12 items), on two factors known to affect time perception: an Emotion Factor (4 items) and an Attention factor (8 items). Secondly, we studied the influence of metacognitive processes on temporal judgments. Thus, we are interested in the influence of metacognitive Control process on performances in two temporal tasks. Our hypothesis was that knowledge about time allowed regulating the temporal judgments. The results of our studies (Study 2 and 3, respectively composed of one and two experiments) confirmed the importance of the Control process on temporal judgments. Thus, mere awareness of the role of attention on perception of time causes a reduction of the attentional effect generally observed (Study 2). Moreover, explicit erroneous knowledge given to participants causes a reduction or even disappearance of automatic emotional effect of anger on the temporal judgments (Study 3). Finally, we have explored the link between Monitoring process and temporal judgments. Our fourth study demonstrated the ability of individuals to accurately estimate the accuracy of their temporal judgments under certain conditions. Indeed, it appears that individuals are sensitive to task difficulty and duration range. These two dimensions affect both temporal judgments and confidence level estimates. Overall, the results of this study emphasize the importance to take account of metacognitive processes in the study of the perception of time. [less ▲]

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See detailChanging Commuter Behaviour through Gamification
Kracheel, Martin UL

Doctoral thesis (2016)

This thesis explores how the dynamic context of mobility, more specifically the commute to and from work in the region of Luxembourg, can be changed through gamified mobile applications. The goal is to ... [more ▼]

This thesis explores how the dynamic context of mobility, more specifically the commute to and from work in the region of Luxembourg, can be changed through gamified mobile applications. The goal is to get a better understanding of the innovative application area of gamified mobility and its potential, as well as to describe its implications for research and practice. This applied research is inspired by a participatory design approach, where information is gained by adopting a user perspective and through the process of conceptualising and applying methods in empirical studies. The four empirical studies described in this thesis employed a mixed-methodology approach consisting of focus group interviews, questionnaires and mobile applications. Within these studies four prototypes were developed and tested, namely Coffee Games, Driver Diaries, Commutastic and Leave Now. The studies show concrete possibilities and difficulties in the interdisciplinary field of gamifying mobility behaviour. This dissertation is composed of seven chapters: Chapter I introduces the topics mobility, games and behaviour; Chapter II presents a proof of concept study (Using Gamification and Metaphor to Design a Mobility Platform for Commuters); Chapter III explains the development and validation of a mobility research tool (Driver Diaries: a Multimodal Mobility Behaviour Logging Methodology); Chapter IV describes the development of a new gamified mobility application and its evaluation (Studying Commuter Behaviour for Gamifying Mobility); Chapter V provides an empirical assessment of the relevance of gamification and incentives for the evaluation of a mobile application (Changing Mobility Behaviour through Recommendations) and Chapter VI is a summary on how to change mobility behaviour through a multilevel design approach (Using Gamification to change Mobility Behaviour: Lessons Learned from two Approaches). The four prototypes help to address the primary goal of this thesis, which is to contribute to new approaches to urban mobility by exploring gamified mobility applications. Coffee games is a proof of concept, low-fidelity implementation of a real-life game that tests gamification elements and incentives for changing indoor-mobility behaviour. The findings of two iterations with a total of 19 participants show the adaptability of the concept to different contexts. The approach to change indoor-mobility behaviour with this mock-up game was successful. Driver Diaries is a methodology to assess mobility behaviour in Luxembourg. The aim with this mobile, digital travel diary is to study features of cross-border commuter mobility and activities in Luxembourg in order to identify suitable elements (activities etc.) for a gamified mobility application, such as Commutastic. After two rounds of data collection (Android and iOS) the records of 187 participants were analysed and the results illustrate the mobility habits of the target audience. Commutastic is a mobility game application that motivates users to avoid peak-hour traffic by proposing alternative after work activities. Analysing the data of 90 participants, we find that the timely offer of an activity in the proximity along with gamification elements involves users and motivates a third of them to engage in alternative mobility behaviours. Leave Now is a gamified recommendation application, which rewards users for leaving their workplace outside of their usual schedule and explores the role of specific gamification elements on user motivation. The study, which was conducted with 19 participants, shows differences between an individual play and a group play condition regarding leaving time changes. The contributions of this thesis to gamification and mobility research and practice span from mobility participations as a game and integral part of our everyday life to methodologies of its successful implementation in the Luxemburgish context. The results show the advantages, disadvantages, and restrictions of gamification in urban mobility contexts. This is an important step towards gamifying mobility behaviour change and therefore towards research aiming at a wellbeing in a better urban life. [less ▲]

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See detailSpace by the numbers
Croonenberg, Dennis UL

Doctoral thesis (2016)

Numerical and spatial abilities have been correlated on many occasions. People who tend to be more proficient at spatial tasks also tend to be more proficient at mathematical operations and understanding ... [more ▼]

Numerical and spatial abilities have been correlated on many occasions. People who tend to be more proficient at spatial tasks also tend to be more proficient at mathematical operations and understanding of numbers. The current work takes several approaches to describe this relationship in further detail by investigating the role of attentional systems and executive control with regards to the processing of numbers and quantities. In a first attempt to do so we provide two studies whose goal it was to replicate the classical association between Arabic digits and response modality (SNARC-effect) and the association between Arabic digits and attentional shifts (Attentional SNARC-effect). In two further studies, we investigated the role of the Attentional SNARC-effect with regards to visual processing and consciousness. In the first of these studies, we made use of a backwards-mask to obscure a single Arabic digit from conscious processing, resulting in the loss of its spatial association in a line-bisection task. Secondly, we used a novel binocular rivalry paradigm to suppress two lateral stimuli from conscious perception and found that the duration of suppression was influenced by the numerical magnitude of a single presented Arabic digit. Specifically, we found that a stimulus on the left side of space would return faster when the Arabic digit was lower than five and that the right side of space would exhibit the same effect when the Arabic digit was higher than five. A crucial manipulation in these last two experiments was an adaptation to the original paradigm for measuring the attentional SNARC-effect. By adding a control-question on the magnitude or parity at the end of each trial, we ensured that the spatial effects would occur during these experiments. Furthermore, this effectively turned the experiments into working-memory tasks. Finally, we tested the influence of a visuo-spatial working-memory task and an addition-task on fronto-parietal network associated with mathematical operations in an event-related fMRI-experiment. This experiment included members of three populations with different levels of mathematical proficiency (Children with Developmental Dyscalculia, Typically developing children and Typical Adults). We found that brain-areas associated with executive control and basic visual processing were affected differently for children with developmental dyscalculia, hinting at a deficiency in visuo-spatial processing in this particular group. [less ▲]

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See detailEFFEKTE EINES MULTILINGUALEN UNTERRICHTSANSATZES AUF DIE SPRACHKOMPETENZEN IM DEUTSCHEN
Planta, Eric UL

Doctoral thesis (2016)

Abstract The reason to conduct this study was based on personal experiences in learning and teaching foreign languages, bilingual teaching methods and the steps of development children have to take in ... [more ▼]

Abstract The reason to conduct this study was based on personal experiences in learning and teaching foreign languages, bilingual teaching methods and the steps of development children have to take in order to gain competencies in the German language. My participation in the module creation of the Teacher Education Program for the University of the Greater Region additionally aroused my awareness of the topic of multilingualism and finally was responsible for the decision to work on the scientific questions of this thesis. The dissertation describes the process of research in order to answer the question if pupils who attend an interregional school with a multilingual language concept are able to show better skills in reading and writing in the German language in comparison to pupils who attend a classical monolingual language-oriented High School. Furthermore it was observed how their language skills progressed in one year, how the status of competencies looks like in comparison to the results of a test of reading and writing skills in German which was taken in the school year 1973/74, how girls developed different from boys, how the language the children usually use at home influenced the results of their tests and how these results were affected by the educational level of the household the children originate from. The opinions and suggestions of the teachers and their pupils as the witnesses of school practice were also taken serious to create an overview of the difficulties. The research design of this study is presented as a polymethodological approach, which is combined with Mixed Methods. In the beginning and at the end of the school year 2013/14 the pupils of both school types were tested with reading and writing items of the Allgemeiner Deutscher Sprachtest ADST, which is a standardized German language test. Through this the effectiveness of the treatment, which corresponds to the school’s German curriculum could be tested as well. Besides it was possible to compare the results of the current tests to the outcomes of the same test battery, which was carried out forty years ago. To support the conclusions of the tests the pupils and their teachers had to fill out a questionnaire in order to identify more background information. By using these tools it was not just possible to receive further background variables but additionally practical problems of teaching German in schools were easily to recognize. As a consequence appropriate suggestions for improvement could be presented aside. The data I received in this combination of longitudinal and cross-sectional study made it feasible to analyse most of it quantitatively and parts of the teachers’ questionnaire answers also qualitatively. The used sample comprised all in all ten teachers and 208 pupils. The test results show that the general proficiencies in German reading and writing of the pupils who attend the school with the multilingual concept do not get ahead of the ones of the children who learn the language in a traditional school with a monolingual German based educationin connection with a classical foreign language educational program. Noticeable is that the multilingual educated children improved more obviously in one school year than the comparable pupils of the High School, who nevertheless showed their qualities on a higher level of competency. The pupils of both schools developed their skills in the progress of their annual education, which underlines the effectiveness of the curriculum-defined treatment. Moreover it became apparent, that both school types were not able to confirm the results of the sample of the ADST forty years ago. Nevertheless the results of the two schools tested here do not give reason to resign. On the contrary it is possible to realise that it is not too late to act. The partial competencies in which the pupils of today performed worse could be exposed with the help of the insights of the text at hand and the direct leverage points to start with corrections and adaptations might be offered here as well. Regarding the outcomes of this study it becomes conceivable to define the work of the language teaching research, which needs to be done in the next years as the imperative necessity to support the idea of a sensible European multilingualism strategy with the focus on the local requirements through the creation of a comprehensive language concept and curriculum. With the help of such an approach regional multilingualism might be in the position to reach people in the field as well as the public at large. A close look at the differences of the test results between the genders revealed, that girls performed better in both tests. This could also be confirmed for the girls of the monolingual school over the multilingual one. The reasons for the differences between the academic achievements in languages between the sexes seem to arise outside the responsibility of the schools, which is underlined through the fact that the gap between the boys’ and the girls’ performance did not increase between the two tests the children had to take. Some approaches to adapt the boys’ language competences outside of school are presented and evaluated in the text. Supplementary it could be shown that the social origin including distance or affinity of the families to education did not have a significant influence on the children’s capacity to perform in the ADST. There also was no direct influence of the family origin to development of the skills from the first to the second test. Additionally, I could manage to show an influence of the languages children use at home to the achievements in the language tests. It was evident that pupils who solely speak German at home showed the best results, ahead of children who at least speak German with one of their parents. Boys and girls who do not speak German at all at home obtained the worst results. The influence of the habits of language usage at home had no significant effect on the skill development from pre-test to post-test. The central statements of the teachers’ questionnaire included the solicitation to improve the German language in school classes in a way that the needs of almost all pupils could be satisfied. Furthermore it is necessary to combine and unify all languages, which are present in a certain region and its schools to one overall curriculum and concept in order to reach the whole population with an integrated language-supporting plan. The starting point might be an adjusted educational policy hand in hand with an adapted education for teachers, who need to be sophisticated for a new understanding of the meaning of languages in the framework of the requirements of a 21-century Europe. The thesis demonstrates and recommends a concrete example including a practically relevant gathering instrument in combination with a self-assessment tool for teachers and pupils, which consequently follows the goal of a specific implementation of a language-aware teaching of the various school subjects. Furthermore the study includes implications for educational- and language policy with hints for a more effective exhaustion of our children’s existing language resources. One of the most important statements of the pupils’ questionnaire is their order of priority of importance of the school subjects for their own forthcoming professional life. This opinion is also reflected in the perceptions of the parents’ behaviour concerning the enrolment of their children to institutes of higher education in the Saarland. They clearly underlined that the most important school subjects in this respect are English, Maths and German. This fact should be taken into consideration for the determination of future educational goals and also for the actual strategic focus of the Saarlandian France Strategy, the Lorraine Germany Strategy and the ambitions of Luxembourg on the basis of an educational policy to strengthen the relationship to the border regions. An idea like the feuille de route as well as the intention of a reinforcement of the French language requires the persuasion of all people, who will be affected by new language developments. The moving closer together of the countries of the Greater Region must not lead to a growing distance to all other European countries and beyond not to the rest of the world. Therefore I personally speak up for an overall Saarlandian Language Strategy, which includes the German language as the fundament for further language learning, which furthermore includes French and English as equitable partners and which shows an appropriate attention to other occurring languages of the region and its people. In the forthcoming years it will be the task of Applied Linguistics and the Language Teaching Research in the Greater Region hand in hand with the teachers in the field to conceive an all-encompassing and realisable language concept and also to combine it with a viable school curriculum. The thesis in hand should be in the position to offer interesting and important cognitions to support the mentioned new language approach. [less ▲]

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See detailDer Schulbesuch in der Schweiz um 1800
Ruloff, Michael UL

Doctoral thesis (2016)

Analysis of school attendance in Switzerland in 1800 // The right to a free public education and in the meantime the duty to send children to school is found in the Swiss Federal Constitution. At the end ... [more ▼]

Analysis of school attendance in Switzerland in 1800 // The right to a free public education and in the meantime the duty to send children to school is found in the Swiss Federal Constitution. At the end of the eighteenth century, school attendance was already mandatory in several cantons, such as Zurich or Vaud. In 1800, the federal government introduced nationwide compulsory education. Unsettled is the question of the actual school attendance. Existing research conveys the image of rather bad and inconsistent school attendance in Switzerland at the end of the eighteenth century. Indeed, there were numerous reasons for children not to go to school: Many children had to work on their parents’ farm in summer. Therefore, in many villages, classes only took place in winter. But in winter, cold weather prevented poorer children with insufficient clothing from going to school. In proto-industrialised regions, where the domestic system was the main source of family income, children had to help out at home in summer and in winter. In many cases, they had to work and earn their own money. Mothers and fathers also kept their children at home for various other reasons: Since there were not enough schools in rural areas, many classrooms were overcrowded – sometimes, more than 100 children gathered in one classroom – and in a bad state with wet walls and no heating. Despite the striking fact that education in the Swiss public is often depicted as the one and only resource of the country, there is not much research about the history of Swiss public schools before 1830 (the years after 1830, when most of the cantons introduced constitutions, are believed as the birth date of public school): There are almost no actual numbers or school attendance rates and only very few sources are to be found in the archives. In the context of a multinational six-year scientific project, the data of the first nationwide school-inquiry (from the year 1799) had been transliterated, edited and published The so-called Stapfer-Enquête with its answers from more than 2400 schools provides a unique opportunity to be concerned with school attendance in 1800. This standardized questionnaire can be seen as a unique source – it is the only nationwide school inquiry answered by teachers at that time. Teachers had to give answers about their income, the school building the subjects they taught as well as the number of students in the classroom. With the help of the data of this inquiry (as well as data of other recently discovered and edited regional school inquiries), this dissertation aims to analyse school attendance in 1800. The core question is: How many children went to school in Switzerland in 1800? The first goal is to track down how many children really went to school in 1800. The analysis also aims to explicate possible motives for good or bad school attendance, with respect to gender, denomination, distance to school plus economic and sociological factors. The question about relative school attendance – as an indicator of the level of education in a society and the quality of education in a specific country is relevant: The matter is of public interest – today and back then. As shown above, there is a clear perception about school attendance in 1800. Some of the theories about this “low” school attendance still exist in the research of history of education: School attendance rates were specifically low in rural and catholic areas. Girls went to school more rarely than boys. The results of this analysis show another picture: Numerous rural and catholic schools used to have quite good school attendance rates and girls also went to school. In order to get a clear picture about school attendance in Switzerland in 1800, this dissertation not only calculates school attendance rates (the sample consists of 126 schools), it also explains differences between high and low rates. By using quantitative and qualitative statistical methods, school attendance data are commented and compared. Apart from doing so, the analysis builds a connection between the school attendance data and historic theory in order to explain the results in a greater context. It refers to previously existing research and clarifies to what extent arguments and beliefs about school attendance in Switzerland in 1800 have to be confirmed or contested. Furthermore, it develops new theses about schools and school attendance in Switzerland at the end of the eighteenth century. An important thesis is, that school attendance relies on the accessibility of the school (the distance between children’s homes and the school building) as well as the identification with and the financial support of public education in a local community. These three factors – accessibility, identification and financial support – have an influence on the quality of school personnel – back in 1800 and today. [less ▲]

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See detailDiversity Preserving Genetic Algorithms - Application to the Inverted Folding Problem and Analogous Formulated Benchmarks
Nielsen, Sune Steinbjorn UL

Doctoral thesis (2016)

Protein structure prediction is an essential step in understanding the molecular mechanisms of living cells with widespread applications in biotechnology and health. Among the open problems in the field ... [more ▼]

Protein structure prediction is an essential step in understanding the molecular mechanisms of living cells with widespread applications in biotechnology and health. Among the open problems in the field, the Inverse Folding Problem (IFP) that consists in finding sequences that fold into a defined structure is, in itself, an important research problem at the heart of most rational protein design approaches. In brief, solutions to the IFP are protein sequences that will fold into a given protein structure, contrary to conventional structure prediction where the solution consists of the structure into which a given sequence folds. This inverse approach is viewed as a simplification due to the fact that the near infinite number of structure conformations of a protein can be disregarded, and only sequence to structure compatibility needs to be determined. Additional emphasis has been put on the generation of many sequences dissimilar from the known reference sequence instead of finding only one solution. To solve the IFP computationally, a novel formulation of the problem was proposed in which possible problem solutions are evaluated in terms of their predicted secondary structure match. In addition, two specialised Genetic Algorithms (GAs) were developed specifically for solving the IFP problem and compared with existing algorithms in terms of performance. Experimental results outlined the superior performance of the developed algorithms, both in terms of model score and diversity of the generated sets of problem solutions, i.e. new protein sequences. A number of landscape analysis experiments were conducted on the IFP model, enabling the development of an original benchmark suite of analogous problems. These benchmarks were shown to share many characteristics with their IFP model counterparts, but are executable in a fraction of the time. To validate the IFP model and the algorithm output, a subset of the generated solutions were selected for further inspection through full tertiary structure prediction and comparison to the original protein structure. Congruence was then assessed by super-positioning and secondary structure annotation statistics. The results demonstrated that an optimisation process relying on a fast secondary structure approximation, such as the IFP model, permits to obtain meaningful sequences. [less ▲]

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See detailAssisted Voluntary Return in Kosovo: A field analysis
Sacchetti, Sandra UL

Doctoral thesis (2016)

The thesis explores the institutional set-up, the underlying ideology and the workings of return assistance projects in Kosovo by applying Bourdieu’s field theory as an analytical framework. It describes ... [more ▼]

The thesis explores the institutional set-up, the underlying ideology and the workings of return assistance projects in Kosovo by applying Bourdieu’s field theory as an analytical framework. It describes experiences with return assistance from the perspectives of the returned persons as well as of those administering the projects. Additionally, it tries to offer explanations for the discrepancies observed between stated policy principles and practices . [less ▲]

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See detailData-driven Repair Models for Text Chat with Language Learners
Höhn, Sviatlana UL

Doctoral thesis (2016)

This research analyses participants' orientation to linguistic identities in chat and introduces data-driven computational models for communicative Intelligent Computer-Assisted Language Learning ... [more ▼]

This research analyses participants' orientation to linguistic identities in chat and introduces data-driven computational models for communicative Intelligent Computer-Assisted Language Learning (communicative ICALL). Based on non-pedagogical chat conversations between native speakers and non-native speakers, computational models of the following types are presented: exposed and embedded corrections, explanations of unknown words following learner's request. Conversation Analysis helped to obtain patterns from a corpus of dyadic chat conversations in a longitudinal setting, bringing together German native speakers and advanced learners of German as a foreign language. More specifically, this work states a bottom-up, data-driven research design which takes “conversation” from its genuine personalised dyadic environment to a model of a conversational agent. It allows for an informal functional specification of such an agent to which a technical specification for two specific repair types is provided. Starting with the open research objective to create a machine that behaves like a language expert in an informal conversation, this research shows that various forms of orientation to linguistic identities are on participants' disposal in chat. In addition it shows that dealing with computational complexity can be approached by a separation between local models of specific practices and a high-level regulatory mechanism to activate them. More specifically, this work shows that learners' repair initiations may be analysed as turn formats containing resources for signalling trouble and referencing trouble source. Based on this finding, this work shows how computational models for recognition of the repair initiations and trouble source extraction can be formalised and implemented in a chatbot. Further, this work makes clear which level of description of error corrections is required to satisfy computational needs, and how these descriptions may be transformed to patterns for various error correction formats and which technological requirements they imply. Finally, this research shows which factors in interaction influence the decision to correct and how the creation of a high-level decision model for error correction in a Conversation-for-Learning can be approached. In sum, this research enriches the landscape of various communication setups between language learners and communicative ICALL systems explicitly covering Conversations-for-Learning. It strengthens multidisciplinary connections by showing how the multidisciplinary research field of ICALL benefits from including Conversation Analysis into the research paradigm. It highlights the impact of the micro-analytic understanding of actions accomplished by utterances in talk within a specific speech exchange system on computational modelling on the example of chat with language learners. [less ▲]

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See detailData-driven Repair Models for Text Chat with Language Learners
Höhn, Sviatlana UL

Doctoral thesis (2016)

Detailed reference viewed: 58 (11 UL)
See detailLaw of the Living: The Semiotic Structure and Dynamics of Law
Ellsworth, Jeffrey UL

Doctoral thesis (2016)

Law is an evolving mental construct. Law, considered distinctly from a legal system, is only a constructed reality which our minds overlay upon the existent world that we experience. This reality is ... [more ▼]

Law is an evolving mental construct. Law, considered distinctly from a legal system, is only a constructed reality which our minds overlay upon the existent world that we experience. This reality is formed by signs and is indefinite and always changing. This reality gives meaning to our world; it turns brute violence into justice and papers into contracts. Law is meaning. Law is merely meaning. And all meaning is law. Not all meaning is law in the legal sense of law, but in the general sense of law which includes the legal sense. Law is semiosis. Hence, Law of the Living because semiosis is always alive in our minds, always contemporary and in the moment. The analysis predominantly employs the philosophy of Charles Peirce. The work focuses on the ontology of law and the problems of legal meaning. Specifically, the first part explicitly addresses the issue of ontology and advocates for an inter-subjective ontological perspective, as well as considering the value and limitations of textualism. The second part addresses the problems of legal meaning due to the reductive nature of communication and the diversity of human perspectives. The former is done through a reconsideration of what law ‘is’ in terms of rules, principles, and factual categories; and the latter through an exploration of the differing conceptions of community and their relevance to law and to society. The work is a combination of legal theory and sociolegal studies culminating in the assertion that the general public must be provided a minimum level of legal education in order to experience legal reality, and not merely a generally analogous social reality, as well as to meaningfully participate in the ongoing legal discourse in society. [less ▲]

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See detailTranszendentaler Schematismus: Zum Verhältnis von Sinnlichkeit und Verstand in Kants Kritik der reinen Vernunft
Birrer, Mathias UL

Doctoral thesis (2016)

In my dissertation, I deal with one of the fundamental topics of Immanuel Kant's Critique of Pure Reason, that is, the relation between sensibility and understanding as the two main and a priori sources ... [more ▼]

In my dissertation, I deal with one of the fundamental topics of Immanuel Kant's Critique of Pure Reason, that is, the relation between sensibility and understanding as the two main and a priori sources of human knowledge. I argue that most interpretations of the First Critique marginalise the role of sensibility as an isolable and irreducible representational capacity of the human mind and the importance of that role sensibility in order to understand some of the main Kantian arguments. In taking Kant’s position as what in contemporary philosophical debates is called a non-conceptualist viewpoint, I provide a detailed exegesis of some of the landmarks in the First Critique, which are, first, the Transcendental Aesthetic that uncovers the pure sensible nature of aspects of our representation of space and time, second, the second step of the Transcendental Deduction that relies on a sense of objectivity provided by sensibility alone, and finally, the Transcendental Schematism that implements our pure conceptual capacity within a non-conceptual representational framework. [less ▲]

Detailed reference viewed: 213 (13 UL)
See detailDisposition Effect, Expectations and Behavior: Essays in Experimental Finance
Carlé, Tim Alexander UL

Doctoral thesis (2016)

This thesis indicates future price expectations and past returns as major determinants for trading decisions in experimental asset markets. Both determinants persist independently of the market ... [more ▼]

This thesis indicates future price expectations and past returns as major determinants for trading decisions in experimental asset markets. Both determinants persist independently of the market institutions continuous double auction market or once per period closing call auction market. Investor subjects are shown to submit more market sell orders after positive returns than after negative returns. They sell more assets with a past positive return, especially when this return is higher than the market return. Expectations about a positive return also lead to more sales of assets with past positive returns. Those investor subjects who have high price expectations buy more frequently and submit higher bids and asks, and those who hold low price expectations sell more frequently and submit lower bids and asks, than average. Future price expectations are adapted based on market outcome when investors receive feedback about market prices. The results do not reveal a significant relationship between transaction volume and the heterogeneity of price expectations, rather they support a positive relationship between the heterogeneity of price expectations and prices. Heterogeneity in price expectations decreases with experience, but markets are not able to homogenize expectations to reach a no-trade equilibrium. [less ▲]

Detailed reference viewed: 186 (16 UL)
See detailCriminal Liability of Managers for Excessive Risk-Taking?
Tosza, Stanislaw UL

Doctoral thesis (2016)

The thesis analyses and evaluates the criminalisation of excessively risky decisions taken by managers of limited liability companies. The potentially disastrous consequences of excessive risk-taking were ... [more ▼]

The thesis analyses and evaluates the criminalisation of excessively risky decisions taken by managers of limited liability companies. The potentially disastrous consequences of excessive risk-taking were powerfully highlighted by the most recent financial crunch, although its dangers are not limited to the times of economic crisis. In the same time risk taking is at the very beginning and at the very core of business activity. By criminalising managers’ excessive risk-taking criminal law enters a sphere, which is at the core of the activity it affects. This research examines the regulation of these selected legal orders, in which excessive risk-taking by managers is criminalised (England & Wales, Germany and France). It is followed by a more in-depth reflection on the role of criminal law in punishing acts of mismanagement, which consist in exposure to excessive risk. This reflection takes a perspective of basic theories of criminalisation and ethical problems inherent to the topic, as well as the interference with other branches of law regulating corporate environment. It demonstrates that it is justified to criminalise excessive risk-taking to a certain extent. It formulates a blueprint how to design criminalisation of such acts taking into account the factual and legal background within which such a criminalisation would have to be fitted. This proposal might serve the national legislator as well as potentially the European one. [less ▲]

Detailed reference viewed: 252 (22 UL)
See detailSubjektives Wohlbefinden von Schülerinnen und Schülern : Welche Faktoren auf der Ebene der Schule/Schulorganisation, des Unterrichts sowie des Individuums sind bedeutungsvoll für das schulische Wohlbefinden von Schülerinnen und Schülern? : Eine qualitative Auswertung von Gruppendiskussionen mit Schülerinnen und Schülern der Sekundarstufe I im Schweizer Kanton Bern.
Gysin, Stefanie Hilda UL

Doctoral thesis (2016)

This dissertation addresses the subjective well-being of school pupils and considers the associated factors which either promote or inhibit their well-being at school. The significance of well-being at ... [more ▼]

This dissertation addresses the subjective well-being of school pupils and considers the associated factors which either promote or inhibit their well-being at school. The significance of well-being at school particularly comes to the fore where schools face the challenge of developing lasting and measurable knowledge and skills in pupils with the aim of preparing them for the tasks of later life. Well-being at school can also play a key role inasmuch as the pupils’ acquisition of skills is supported by their positive feelings and attitudes towards school because these emotions and mindsets provide a stabilising and trusting basis for learning and development (cf. e.g. Hascher, Hagenauer & Schaffer, 2011). The identification of influential variables is called for, particularly for the purposes of providing targeted support for well-being at school and preventing unwanted regressions – which have, however, been empirically demonstrated in pupils in later school years (cf. Czerwenka et al, 1990). This study therefore explores which factors at the school/school administration level, the lesson level and the individual level are significant to the subjective well-being at school from the perspective of the secondary school pupils that were surveyed, and whether differences between boys and girls can be established in these respects. The response to the research questions is based on a methodologically qualitative approach. Male and female secondary-level pupils (year 8) from schools in the Swiss Canton of Bern were asked questions in 16 single-sex group discussions. Their comments and opinions were evaluated using the qualitative content analysis method set out by Mayring (2010). In this regard, the following main conclusions were drawn as an overview: At the school/school administration level, both boys and girls find that the high frequency of examinations and the poor scheduling of the examinations that they are required to pass put a strain on them. According to their comments, the generally long school days and the amount of homework, exam preparation and apprenticeship applications that they are required to do at the same time also lead to stress and a feeling among the pupils of being overloaded. At the lesson level, well-being among pupils is promoted by lessons that are not boring (in terms of subject matter) and are sufficiently varied in their methodological format. With regard to a teacher’s character and personality traits, both sexes feel that a teacher has a positive impact on their well-being at school when he or she is sociable, close to the pupils, kind, and self-critical with an open, relaxed and humorous manner around the pupils. It is striking, however, that the groups of boys cite the aspect of the teacher’s character and personality traits and the quality of the relationship between the teacher and the pupils as a factor relevant to their level of well-being much more frequently and in more detail than the girls. At the individual level, girls link their well-being at school to a high degree to their learning-related emotions and motivational orientation. In contrast to the boys, the girls emphasise the importance of achieving good grades much more frequently, which also plays a crucial role in girls experiencing positive emotions. The micro-social environment of pupils – their peers and their parents – is also a relevant factor governing their well-being. Whereas boys see their peers as an important motivator in coming to school and as a significant factor in their enjoyment of school, girls emphasise the importance of their peers as an important emotional crutch for problems (at school) and failures at school (e.g. bad grades). Both boys and girls see their parents as an important and reliable source of support for learning which also contributes to their sense of well-being at school. [less ▲]

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See detailEmotional reactivity and emotion regulation in children with autism spectrum disorder.
Pinto Costa, Andreia UL

Doctoral thesis (2016)

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and social interaction, as well as restricted and repetitive patterns of behaviors and ... [more ▼]

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and social interaction, as well as restricted and repetitive patterns of behaviors and interests. Additionally, children with ASD often present internalizing and externalizing problems such as anxiety, depression, and conduct problems. These problems can hinder children’s social competence and development and may have repercussions into adolescence and adulthood. It is believed that internalizing and externalizing problems originate from children’s emotional difficulties such as difficulties in emotional reactivity and emotion regulation. The aim of the present thesis was therefore to examine the role of emotional reactivity and emotion regulation in children with ASD. Emotional difficulties in children with ASD may be due to several factors: ASD’s core symptoms, children’s other characteristics such as alexithymia, and parents’ characteristics. The relation between these factors to emotional difficulties in children with ASD have been integrated into a model of the emotional reactivity and emotion regulation difficulties in children with ASD. Based on the model’s assumptions different hypotheses were formulated for the present thesis: (a) ASD’s core symptoms contribute to children’s emotional difficulties by increasing emotional reactivity, decreasing emotion regulation, and increasing emotional incoherence; (b) children’s alexithymia also contributes to children’s emotional difficulties by increasing them; (c) ASD’s core symptoms are related to parents’ characteristics by decreasing parents’ emotion regulation capacity, increasing parents’ stress reaction, and decreasing parents’ frequency of interaction with their children; (d) difficulties in emotional reactivity and emotion regulation in children together with alexithymia are also related to parents’ characteristics; (e) in turn, parents’ frequency of interaction with the child also contributes to children’s difficulties in emotional reactivity and emotion regulation. Applying a multimethod approach where parents-reports, parents’ self-reports, observations, and physiological indicators were used, 37 children with ASD and 66 typically developing (TD) children and their parents were assessed. It was found that: (a) children with ASD had more emotional reactivity, less emotion regulation ability, and more emotional incoherence than TD children; (b) children’s alexithymia contributed more than ASD diagnosis to the explanation of some aspects of emotional reactivity and emotional incoherence but not of emotion regulation; (c) parents of children with ASD had more emotion regulation difficulties, more stress, and interacted less frequently with their children than parents of TD children; (d) parents’ perceptions of children’s difficulties contributed more to parents’ emotion regulation capacity and as much to parents’ stress as ASD diagnosis; moreover, children’s alexithymia also contributed more to parents’ frequency of interaction with their children than ASD diagnosis; and (e) parents’ frequency of interaction with their children contributed to more positive and negative emotional expressions and to the use of better emotion regulation strategies in children. The present findings highlight the complexity of emotional difficulties in children with ASD by suggesting that difficulties in emotional reactivity and emotion regulation are reflected at the subjective, observational, and physiological levels. Furthermore, these difficulties are influenced by different factors: children’s ASD characteristics, children’s other characteristics such as alexithymia, and parents’ characteristics. Given the relevance of emotional difficulties to internalizing and externalizing problems in children with ASD it is important that interventions include a multicomponent approach to emotional difficulties in ASD. Furthermore, interventions would benefit from integrating children’s alexithymia and parents’ characteristics such as their difficulties with emotion regulation and stress to help alleviate emotional difficulties in children with ASD. Finally, parents’ trainings on learning strategies to deal with their children’s emotional reactivity might prove beneficial both for parents and for children. [less ▲]

Detailed reference viewed: 311 (30 UL)
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See detailLegal Ontology for Nexus: Water, Energy and Food in EU Regulations
Rahman, Md Mizanur UL

Doctoral thesis (2016)

Objectives of the thesis are – (a) to identify the problems in water-energy-food nexus from ICT and Law point of view and to propose theoretically a legal knowledge framework for water-energy-food nexus ... [more ▼]

Objectives of the thesis are – (a) to identify the problems in water-energy-food nexus from ICT and Law point of view and to propose theoretically a legal knowledge framework for water-energy-food nexus in order to reduce those problems technologically, (b) to construct and implement legal ontology for nexus extracted from EU water, energy and food Regulations in OWL 2 language, which is a part of the grater work of implementing legal knowledge framework for water-energy-food nexus pro-posed through the compilation of objective (a). Considering these objectives, this thesis presents total five chapters. Chapter 1 is dedicated to fulfill the requirement of objective (a) and the rest chapters are devoted for objective (b). More particularly chapter four presents technical descriptions of the legal ontology for nexus, while chapter two and three articulate methodological aspect of it. Chapter five evaluates legal ontology for nexus. Additionally, besides the list of references, annex 1 delivers all asserted restrictions used in this ontology and annex 2 provides the links of all modules and documentations of legal ontology for nexus. [less ▲]

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See detailPhased Array Antenna with Dielectric Phase Shifters
Moonshiram, Anusha UL

Doctoral thesis (2016)

This PhD Thesis entitled, “Phased Array antenna with Dielectric Phase Shifters” presents a candidate for a planar, elegant and simple alternative to replace the parabolic antenna on the roof of your house ... [more ▼]

This PhD Thesis entitled, “Phased Array antenna with Dielectric Phase Shifters” presents a candidate for a planar, elegant and simple alternative to replace the parabolic antenna on the roof of your house and that of your neighbours. A parabolic antenna is bulky, has an average weight of 25 kg, and it is usually attached with an arm fixture of an average depth of 30 cm. Unlike the parabolic antenna which represents a large unsightly looking necessity on your roof, or balcony of your house, the planar antenna presented here is elegant and discrete. It is cheaply made with simple lightweight dielectric sheets and is mounted directly as a planar surface on the wall of your house oriented towards the satellite Astra 1M and requires no extra mount fixture. The planar antenna is less subjected to environmental conditions such as wind or hail and must not be constantly readjusted to optimize TV reception. The proposed antenna is made of 32 by 32 elements of a length and a spacing of half wavelength λ/2 with dielectric phase shifters to orient the main lobe with a 3° beamwidth by 45° in azimuth and from 23° to 43° in elevation. The dielectric phase shifters use a high dielectric constant of εr 10.2 on top of an antenna array with a substrate of εr 2.2. The difference between the high and the low dielectric value on a coplanar waveguide (CPW) feedline requires a maximum length of 18.7 cm for the 32nd antenna element in order to move the main lobe by a maximum of 45°. The CPW feedline is ideal to minimize mutual coupling among antenna elements. The antenna gain is 32 dBi and the beamwidth is 3°. It occupies a total size of 72.25 cm x 40.96 cm x 6.22 cm. The antenna presented here is targeted for the reception of satellite television in Europe broadcasting from 10.7 to 12.7 GHz. As it consists of frequency independent antenna elements, it can be resized for any desired frequency range in any part of the world. In short, it is a cheap, light, adaptable and discrete design and especially convenient in regions where unsightly parabolic antennas are prohibited. [less ▲]

Detailed reference viewed: 178 (17 UL)
See detailLes contrats liés à la lumière de l'harmonisation européenne du droit des contrats
Jeanpierre, Delphine UL

Doctoral thesis (2016)

Cette thèse étudie la notion de contrats liés à travers le prisme de l'harmonisation européenne du droit des contrats. Dans certains droits nationaux, pléthore de travaux d'ensemble ont été réalisés sur ... [more ▼]

Cette thèse étudie la notion de contrats liés à travers le prisme de l'harmonisation européenne du droit des contrats. Dans certains droits nationaux, pléthore de travaux d'ensemble ont été réalisés sur la notion de groupes de contrats, chaînes de contrats, ensembles contractuels ou encore de l'interdépendance contractuelle. S'appuyant sur les travaux déjà existants dans ce domaine, ce travail appréhende cette notion sous un éclairage européen. En adoptant la définition la plus large possible des liaisons entre contrats cette thèse explore l'appréhension par le droit européen des problématiques spécifiques des contrats liés ainsi que l'articulation entre le droit européen et les droits nationaux autour de ces problématiques. [less ▲]

Detailed reference viewed: 184 (18 UL)
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See detailESSAYS ON SLOT ALLOCATION AND EMISSION LICENSES IN AIRPORTS
Wan, Xi UL

Doctoral thesis (2016)

Detailed reference viewed: 79 (17 UL)
See detailForce-Guided Robotic Assembly Process: Control and Contact-State Recognition
Jasim, Ibrahim UL

Doctoral thesis (2016)

This thesis addresses developing novel Contact-State (CS) modeling, control strategy, and environment position localization (position searching) for force-guided robotic assembly processes of rigid and ... [more ▼]

This thesis addresses developing novel Contact-State (CS) modeling, control strategy, and environment position localization (position searching) for force-guided robotic assembly processes of rigid and flexible objects. For the CS modeling, the wrench (Cartesian force and torque) signals of the manipulated object are captured for different phases of the considered assembly processes and using the Expectation Maximization-based Gaussian Mixtures Model (EM-GMM), a recognizer is developed for each CS of the assembly. The suggested EM-GMM CS modeling scheme is shown to have excellent Classification Success Rate (CSR) with reduced computational efforts. For the control part, it is shown throughout the thesis that a force-guided robotic assembly process is a hybrid nonlinear system with arbitrary switching signal resulted from the constraints arbitrary switching during the assembly. Furthermore, the robot dynamics is frequently unknown, which is the case in many industrial robots, that would make the force-guided robotic assembly process to be an unknown hybrid nonlinear system with arbitrary switching. In order to overcome such a control challenge, a Decentralized Robust Adaptive Fuzzy Control (DRAFC) strategy is derived that guarantees stable performance under constraints arbitrary switching and unknown dynamics. For the environment position localization, the EM-GMM CS modeling scheme is integrated with a spiral search path and the precise hole position is identified for cases of position uncertainty. Experiments are conducted on a KUKA Lightweight Robot (LWR) doing different force-guided assembly tasks for rigid and flexible objects. Excellent performance is reported for the proposed EM-GMM CS recognition scheme, the DRAFC strategy, and the suggested position searching algorithm. The suggested EM-GMM CS recognition, DRAFC strategy, and position localization schemes are compared with the availably corresponding schemes and the superiority of the suggested schemes is shown. The reasons behind the superiority of the EM-GMM CS recognition scheme are the accommodation of the captured signals non-stationary behavior, employing optimized number of GMM components in the modeling process, and employing the EM algorithm that iteratively increases the log-likelihood. The causes behind the superiority of the DRAFC strategy are addressing the unknown nonlinear dynamics of the robot, accommodating the constraints arbitrary switching, and the robustness against possible dynamics parameters drift. The reasons behind the surpassing of the suggested position localization strategy are the robustness against the surface roughness and reduced computational efforts. The proposed EM-GMM CS modeling scheme, DRAFC strategy, and position searching scheme are applied to the entire peg-in-hole assembly processes of rigid and flexible objects. Excellent Localization Success Rate (LSR) was resulted when using the suggested schemes. Furthermore, the proposed CS modeling scheme, control strategy, and localization approach are applied to a couple of applications in automotive industry; the first one is the camshaft caps assembly of a cylinder head and the other is the air-intake manifold assembly of a powertrain. Efficient force-guided robotic assembly processes are obtained for both considered applications. [less ▲]

Detailed reference viewed: 396 (66 UL)
See detailLa protection juridictionnelle dans le Mécanisme de surveillance unique ou MSU, premier pilier de l'Union bancaire européenne
De Re, Etienne UL

Doctoral thesis (2016)

The combination of article 47 of the EU Charter of Fundamental Rights and article 19, 1st paragraph of the Treaty on European Union defines and protects the fundamental right to an effective remedy. Those ... [more ▼]

The combination of article 47 of the EU Charter of Fundamental Rights and article 19, 1st paragraph of the Treaty on European Union defines and protects the fundamental right to an effective remedy. Those primary law provisions shall be interpreted in the light of article 6 of the European Convention on Human Rights, which traditionally constitutes the most favoured source of inspiration for the Court of Justice of the European Union. The sui generis legal order of the European Union offers and protects a high level of judicial protection, as the Lisbon Treaty establishes a triple guarantee of fundamental rights to be effectively enforced via a complete system of legal remedies and procedures at different levels. More than ever, legal experts having a good command of economics highlight the fact that credit institutions are, per se, transmission channels from banking crises to the real economy. More than necessary, it is vital to reach and maintain the efficiency of the Single supervisory mechanism (SSM), first pillar of the European banking Union. The overall objective of public interest to preserve the financial stability of the euro zone and of the European Union as a whole prompted the legislature to confer wider (the widest?) powers upon competent authorities; nevertheless, these authorities must ensure that supervised banks are guaranteed the right to an effective judicial protection throughout the whole process. Do private interests weaken the general objective of financial stability, or is the SSM a balanced mechanism? [less ▲]

Detailed reference viewed: 216 (45 UL)
See detailEtude biomécanique comparative de cinq différents systèmes de fixation utilisés dans les cas d'ostéotomies tibiales valgisantes: Essais expérimentaux et simulations numériques incluant les forces musculaires
Diffo Kaze, Arnaud UL

Doctoral thesis (2016)

This research project was carried out in partnership with the Orthopaedic and Traumatology service of the “clinique d’Eich” of the Centre Hospitalier de Luxembourg. The main objective consisted in a ... [more ▼]

This research project was carried out in partnership with the Orthopaedic and Traumatology service of the “clinique d’Eich” of the Centre Hospitalier de Luxembourg. The main objective consisted in a comparative biomechanical study of the stability of five different currently used implants for open-wedge high tibial osteotomy (HTO). The following implants were tested in the comparative biomechanical study: Contour Lock HTO, PEEKPower HTO, iBalance HTO, TomoFix standard and TomoFix small stature. The implants were chosen freely from the market and there has not been any funding or link to any of the manufacturers. The comparison was first made experimentally using static compression loading to failure and dynamic loading to failure tests, then computationally using simulations by mean of the finite element method. Muscle forces were predicted using musculoskeletal modeling and applied to the finite element models of the lower limb that simulated the stance phase of the gait cycle. The finite element models created included all the bones of the lower limb, except those of the foot, as well as the menisci, the articular cartilage layers of the knee and the patellar tendon which was modelled by springs. The comparative study using numerical simulations was done considering two separate loadings: (1) application of a compressive load on the tibial plateau and (2) consideration of muscle forces. The comparison of the two types of loading (1) and (2) showed that loading (1) used during the mechanical tests is compatible with a realistic loading of the tibia with the leg at 15 % of the gait cycle during slow walking. Observations from numerical simulations considering loading (2) emphasized the necessity to take into account the muscle forces in the testing protocols and implant design process. The results of the numerical simulations considering loading (1) were in line with the findings of the experimental study. All the implants tested showed sufficient stability during static loading. All the specimens failed due to fracture of the opposite cortical bone. In regards to the results of this study, the implant iBalance offered the best mechanical stability to the operated tibia, and the PEEKPower plate the worst. Simplifications were made to reduce the complexity of the different physical and numerical models; hence the transposition of the obtained results to clinical settings should be done with precaution. There is no conflict of interest in relation to this work. [less ▲]

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See detailDER EFFEKT DER SCHULFORM AUF DIE SCHULISCHE LEISTUNG UND DAS FACHSPEZIFISCHE AKADEMISCHE SELBSTKONZEPT VON SCHÜLERINNEN UND SCHÜLER IN LUXEMBURG
Schaltz, Paule UL

Doctoral thesis (2016)

The present study investigated the effect of the attended school track on future academic achievement and subject-specific academic self-concept of students. Based on the assumptions of the Aptitude ... [more ▼]

The present study investigated the effect of the attended school track on future academic achievement and subject-specific academic self-concept of students. Based on the assumptions of the Aptitude-Treatment Interaction model (Cronbach & Snow, 1981), we expected an effect of previous school achievement and attended school track on subsequent school achievement and subject-specific academic self-concept. More specifically, we expected that previously high achieving students would benefit from attending the academic track while previously low achieving students would benefit from attending the non-academic track. School achievement and self-concept data were analysed using linear regression models and propensity score matching for a set of students (n = 3200), who attended either an academic or non-academic school track during the first three years of secondary school in Luxembourg. The results showed that the highest achieving students benefited from attending the academic track whereas the lowest achieving students benefited from going to the non-academic track in terms of their subsequent school achievement. However, most students in the academic school track outperformed students with similar academic profiles in the non-academic school track, showing clear benefits of attending the academic track. With regard to the subject-specific academic self-concept, data showed that students who attended different tracks assessed their school performance differently. Interestingly, students with comparable academic performances reported a higher subject-specific academic self-concept when attending the non-academic track compared to students attending the academic track. However, this effect disappeared for most school subjects after controlling for the student’s achievement-related ranking within their track. In conclusion, although very high and very low achieving students seemed to benefit from the tracked school system with regard to their subsequent school achievement, such benefits are less clear for the majority of the student population. [less ▲]

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See detailTowards Ambient Intelligent Applications Using Models@run.time And Machine Learning For Context-Awareness
Moawad, Assaad UL

Doctoral thesis (2016)

Ambient Intelligence (AmI) constitutes a new paradigm of interaction among humans, smart objects and devices. AmI systems are expected to support humans in their every day tasks and activities. In order ... [more ▼]

Ambient Intelligence (AmI) constitutes a new paradigm of interaction among humans, smart objects and devices. AmI systems are expected to support humans in their every day tasks and activities. In order to achieve this goal, these systems require augmenting the environment with sensing, computing, communicating, and reasoning capabilities. Due to advances in technology, sensors are getting more powerful, cheaper and smaller, which stimulated large scale development and production. These sensors will generate a big amount of data and can easily lead to millions of values in a short amount of time, which can quickly reach the computation and storage limits when it comes to structuring and processing the data. For this problem, we propose a concept of continuous models that can handle highly-volatile data, and represent the continuous nature of sensor data in an efficient and compact way. We show on various AmI datasets that this can significantly improve storage and efficiency. One important goal of AmI systems is to transform living and working environments into intelligent spaces able to adapt to their users’ needs and desires in real-time. In this sense, we call AmI applications context-aware, meaning that they use environmental information to adaptively provide more relevant and better services to the user. However, AmI systems are composed from heterogeneous components, operating in an open and dynamic environment. Each of these components can have different storage and computation capabilities. They might not have all the information needed to derive context information, and they might not be reachable all the time for various reasons. In this thesis, we present a contextual reasoning solution adapted for component based platforms. Our solution can derive contextual information in a distributed way and can handle inconsistencies when contradictory information is received from several components. Other than the storage and computation efficiency, several qualities need to be satisfied according to the different contexts. Privacy is one of these qualities. AmI services will rely more and more on personal data that is vastly collected, stored, and exchanged with other third parties in order to provide added-value services. Such data are sensitive and often related to personal activities and therefore can lead to privacy risks, especially when data is shared with high precision and frequency. However, this privacy quality can be relaxed in some contexts, for example in an emergency situation in order to increase utility or efficiency. This leads to the need of developing an adaptive solution that is able to react to context changes in real-time and involve optimizing conflicting objectives. For this challenge, we propose to use blurring components as our main privacy preservation elements. The idea behind this approach is that, by gradually decreasing the data quality, a blurring component is able to hide some of the personal data delivered by sensors while still keeping the necessary information for the services to work. In order to find a good trade-off between these different conflicting objectives, we adapt a multi-objective evolutionary algorithm to run directly on top of domain specific models. We then apply it as our main optimization engine on models@run.time to keep adapting the different qualities, when the context change. Finally, AmI services are expected to be tailored for different users’ needs in a seamless and unobtrusive way. Meaning that they should be able to detect contexts and learn habits automatically with the least possible intervention of users. In order to achieve this, machine learning (ML) techniques need to be merged at the core of reasoning models. These techniques offer powerful tools to automatically detect patterns, categorize contexts, build usage profiles, represent data with compact mathematical hypothesis and provide statistical information vital for the intelligent aspect of AmI. This dissertation ends up by opening new directions on how to model and adapt machine learning techniques to fit for AmI platforms. Overall, this thesis provides solutions for the next leap of technology, where sensors become ubiquitous. Our solutions, implemented in an open source framework KMF, allow to create efficient and distributed, data and component models for IoT, adaptable at runtime leveraging multi-objective optimization to find good tradeoff between qualities for the current context, and machine learning techniques to derive contextual rules, profile and learn habits automatically. [less ▲]

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See detailStudents’ affect and motivation: Assessment, structure, and development
Gogol, Katarzyna UL

Doctoral thesis (2016)

Students’ affect and motivation are key determinants of academic effort, academic choices, and academic success. The present dissertation scrutinizes students’ affect and motivation with respect to (a ... [more ▼]

Students’ affect and motivation are key determinants of academic effort, academic choices, and academic success. The present dissertation scrutinizes students’ affect and motivation with respect to (a) possibilities of economic assessment, (b) structure, and (c) development. To this end, the present dissertation focusses on three central affective-motivational constructs that have a long tradition in educational science and are not only important with respect to students’ learning, but are also considered to be vital learning outcomes themselves: academic self-concept, academic interest and academic anxiety. This dissertation includes three studies that are based on large-scale data sets. In the first study, we examined the feasibility of short scales to assess affective-motivational constructs. This is an important research question, as testing time in educational research is typically scarce, which makes the use of long scales problematic. Specifically, we developed three-item and single-item scales for general and subject-specific (i.e., mathematics, German, French) academic anxieties and academic self-concepts and evaluated their psychometric properties by systematic comparison with corresponding long scales. Our results showed that (1) all three-item scales showed satisfactory reliabilities and substantial correlations with long scales, (2) the reliabilities and correlations of single-item measures were somewhat lower. Importantly, however, (3) the correlational patterns of the three-item as well as single-item scales with important students’ characteristics (e.g., gender, school satisfaction, achievement) were similar to those obtained with the corresponding long scales. We concluded therefore that when a study design requires short measures, three-item scales and perhaps even single items may be used as reasonable alternatives for assessing academic anxiety and academic self-concept. The second study tackled the question of structural models of students’ affect and motivation. With regard to academic self-concept, much research has been devoted to the structural conceptualization of this construct. Current structural models consider academic self-concept to be not only subject-specific by nature but also hierarchically organized with general academic self-concept operating at the apex of the hierarchy. Although theoretical considerations and consistent correlational patterns of academic interest and academic anxiety measures indicate that these constructs show similar structural characteristics to academic self-concept, structural models that can account for and test these characteristics are missing. Therefore, first, we specified and examined structural models of academic self-concept, academic interest, and academic anxiety, separately. Our results underscored empirically the structural similarities between the constructs. Furthermore, theoretical predictions and empirical results indicate interrelations between the different affective-motivational constructs. In order to properly examine the constructs’ interrelations, the multidimensional and hierarchical organization of the constructs needs to be taken into account. Therefore, in the next step, we developed an integrative model which provides a comprehensive formal psychometric representation to capture and analyze the complex interplay of general and subject-specific (i.e., mathematics, French, and German) components across academic self-concept, academic interest, and academic anxiety. Finally, we validated the integrative model with respect to indicators of students’ achievement. In the third study we investigated the developmental dynamics of students’ affect and motivation from Grade 7 to 9. Importantly, in previous developmental research the multidimensional and hierarchical organization of the constructs was rarely taken into account. Consequently, little is known about the manifold developmental dynamics of general and subject-specific components of academic self-concept, academic interest, and academic anxiety. Therefore, we applied longitudinal models that capture the hierarchical and subject-specific structure of these constructs to contribute to a fuller and more nuanced understanding of their developmental processes. The investigated constructs showed moderate differential stabilities at the general and subject-specific levels. Further, the development of academic self-concept, academic interest, and academic anxiety seems to be characterized neither by top-down nor bottom-up developmental processes. Rather, general and subject-specific components of the constructs in Grade 9 were shown to be primarily a function of the corresponding components in Grade 7. However, there proved to be several negative ipsative developmental processes across different school subjects. [less ▲]

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See detailPlurilingual Approaches to Spatial Education – Perspectives of Primary Schools in the German Context
Weißenburg, Astrid UL

Doctoral thesis (2016)

‘Plurilingual Approaches to Spatial Education – Perspectives of Primary Schools in the German Context’ is a theory-based didactic study which centers on the role of migratory languages in primary ... [more ▼]

‘Plurilingual Approaches to Spatial Education – Perspectives of Primary Schools in the German Context’ is a theory-based didactic study which centers on the role of migratory languages in primary geography education. Hereby, theories of space, concept development, and plurilingualism are discussed while migratory languages are recognized and actively applied in the content-based teaching of primary geography classes. A language-sensitive approach to plurilingual concept development processes is fostered in spatial education. The paper can be divided into three parts: Firstly, established theories on space, language, and plurilingualism are constituted. Highlighting possible interlinkages, a symbiosis of the different fields is developed for the educational context. Secondly, a didactical model is derived in order to be able to apply theory guided discussions to daily educational practices. Thereby, the approach of Content and Language Integrated Learning (CLIL) is incorporated into the model. Subsequently, the newly generated didactic model is intensively discussed in all its complexity. In relationship to the model, an exemplary CLIL learning sequence is developed. Thirdly, this best-practice learning sequence is implemented in the field of primary school education in Germany. This process is accompanied by scientific research in order to gain insights into the concept development processes of eight-year-old learners. Here, development is understood as emergence rather then progression. Significant concept development processes as well as the core concept are retrieved through the application of the Grounded Theory Methodology (GTM). The paper closes with a critical discussion on the relevance of meaning-making processes in plurilingual spatial education and their prospects in the realm of geography didactics. [less ▲]

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See detailLe discours juridique dans la "société du risque" : Regard réflexif sur l'évolution de l'assurance et du principe de précaution en droit
Dufour, Pascale UL

Bachelor/master dissertation (2016)

This research provides a critical analysis of the law applicable to two dimensions of risk management: damage compensation through insurance and risk prevention by the precautionary principle. The ... [more ▼]

This research provides a critical analysis of the law applicable to two dimensions of risk management: damage compensation through insurance and risk prevention by the precautionary principle. The interdisciplinary perspective offers a critical perspective on the interaction of law with political, economic, scientific and social rationalities by the opposition of two theories: the Risk Society of Ulrich Beck and Asurantial Society of François Ewald. The different meanings of private insurance limits and dissonant discourse on the legal strategies used against risks are revealed. The thesis provides essential guidelines to the critical legal thinking. The originality of the analysis angle, which takes into account legal developments in regards of the changes in political rationality that occurred in the nineteenth century with the industrialization of Western societies, extends legal epistemology. A critical reflection on the evolution of theoretical concepts of law and its expected social role within society, considering the political and economical interplay, is suggested. [less ▲]

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See detailEssays in Empirical Corporate Finance
Rolle, Gudrun UL

Doctoral thesis (2016)

The thesis comprises three independent though topically related papers that empirically investigate the relationship between corporate governance and finance. The first paper ‘Corporate Governance, Input ... [more ▼]

The thesis comprises three independent though topically related papers that empirically investigate the relationship between corporate governance and finance. The first paper ‘Corporate Governance, Input Market Regulation, and Equity Prices’ links how anti-competitive regulation in the input market impacts the effectiveness of corporate governance in terms of firm and market performance. For stock price related data, I find that governance and regulation are complements: abnormal returns of hedge portfolios based on corporate governance quality are only attainable in industries which are highly competitive. For companies in relatively competition-protected industries governance has no impact on market data. Turning to business fundamentals, the relationship reverses and governance and competition become substitutes, i.e. companies’ operating performance benefits from strong governance if the company operates in a relative anti-competitive industry. The second paper ‘Corporate Governance and Idiosyncratic Skewness: Evidence from External and Internal Provisions’ (co-authored with Thorsten Lehnert) analyzes the relationship between corporate governance and firm-specific skewness of stock returns for U.S. firms. Since firm-level skewness determinants are differences in investor opinion, information and information asymmetries, and companies with good corporate governance are more informative and transparent than their counterparts with less shareholder protection, we argue that differences in the quality of corporate governance matter to idiosyncratic skewness. We test this hypothesis by analyzing the impact of external as well as internal governance provisions, and are thus able to provide an overall understanding of the relationship between governance and firm-specific return asymmetries. The results show that better governance leads to a reduction in idiosyncratic skewness in relatively non-competitive industries. In industries that face higher levels of competition, governance has no impact on firm-specific return skewness. Especially the results of the internal governance analysis are robust and both statistically and economically significant. The third paper ‘Compensation Structure under Debt Insurance’ investigates the relevance of compensation structure as a means towards managerial incentive setting. Inside debt is designed to align managers with debt holders, and to mitigate risk-taking versus risk-avoiding conflicts of interest between shareholders and bondholders. Thus it constitutes an efficient component in the equity- and debt-like compensation structure of executives. However, under debt insurance the alignment structure should shift – towards the interests of equity holders. And it does. Exploiting first-time initiations of credit default swaps (CDS) on a reference entity, I show that companies whose debt can be insured through CDS significantly reduce their CEO’s relative debt-equity and incentive ratios, therefore shifting the incentive structure towards equity holders. The results are economically large and robust. [less ▲]

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See detailLa répartition des risques dans les partenariats public-privé et le déficit public
Möric, Kim Eric UL

Doctoral thesis (2016)

The development of public-private partnerships (PPP) in some Member States of the European Union is related to the off balance sheet treatment of these PPP regarding ESA 10 and regarding the limit of the ... [more ▼]

The development of public-private partnerships (PPP) in some Member States of the European Union is related to the off balance sheet treatment of these PPP regarding ESA 10 and regarding the limit of the government deficit since the Maastricht Treaty. The thesis is studying the origin, the practice, the conditions and the incidences of the off balance sheet treatment of PPP under ESA 10 and allowing Member States to hide government deficit. [less ▲]

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See detailAnalysis of Bandwidth Attacks in a Bittorrent Swarm
Adamsky, Florian UL

Doctoral thesis (2016)

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See detailA Geographical Analysis of Bicycle Sharing Systems
Médard de Chardon, Cyrille UL

Doctoral thesis (2016)

This thesis evaluates the performance of bicycle sharing systems (BSS), autonomous systems of accessible bicycles that can be easily used for one way trips, and determines whether they are successful at ... [more ▼]

This thesis evaluates the performance of bicycle sharing systems (BSS), autonomous systems of accessible bicycles that can be easily used for one way trips, and determines whether they are successful at achieving promoted social and environmental outcomes through quantitative and qualitative methods. Such systems are typically surrounded by positive narratives of success, health, environmental and social benefits. This work challenges these notions. This thesis begins with the formalisation of BSS station level and trip data revealing alternative data contained within. Combined with spatiotemporal data analysis, this allows the estimation of trips, a potential measure of success. Due to most operators not providing consistent or comparable metrics of usage this work opens this heavily promoted technological transport innovation’s performance for public scrutiny. Performance estimates of 75 case studies show a majority having less than two trips per day per bicycle, suggesting a poor investment, regardless of existing social justice issues and exaggerated environmental benefits. Using this metric this work determines which attributes impact performance. While station density and cycling infrastructure, among others, are found to impact performance, results challenge promoted practice. Formalisation yielded rebalancing, the moving of bicycles to adjust to demand exceeding supply. Spatiotemporal data analysis and interviews with operators provides the first description of applied rebalancing, providing an alternative perspective to the many theoretical optimisation models. Results show rebalancing is spatially selective and influencing BSS outcomes, potentially contrary to its purpose. Finally, this thesis, through a critical urban sustainability perspective, presents darker aspects of BSS, beyond the golden narratives, showing conflicts of interest, controversy and the commercialisation of an initially environmental and anti-consumerism concept. Existential questions are raised due to BSS, mostly privately operated, providing benefits to an already advantaged class while public space is privatised and urban advertising increased. This work concludes by suggesting that alternative investment to bicycle sharing systems, such as cycling infrastructure, may be more beneficial and just. [less ▲]

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See detailEvaluation of cognitive ability in heterogeneous student populations: Development of the Test of Cognitive Potential
Muller, Claire UL

Doctoral thesis (2016)

Evaluation of cognitive potential of individuals with diverse backgrounds often presents a challenge. Individuals’ imperfect mastery of the language of instruction in particular presents a major threat to ... [more ▼]

Evaluation of cognitive potential of individuals with diverse backgrounds often presents a challenge. Individuals’ imperfect mastery of the language of instruction in particular presents a major threat to validity of results and prohibits comparison to performance with better language skills. Eliminating language from test instruction may be a solution to this problem. The present thesis presents the development and validation of the innovative Test of Cognitive Potential (TCP), a language-free, tablet-based group-assessment tool designed to measure fluid intelligence within children in grade 4 (regular age between 9 and 10). Using dynamic visual instruction videos, task requirements are presented visually, without adding any verbal clarification. In order to sample a wide array of cognitive processes on different contents (domain-general, quantitative and semantic-syntactic reasoning as well as visual processing), the TCP includes a variety of subtests. Using confirmatory factor analysis, the overall structure of the test is evaluated within student samples from Luxembourg, Germany and Brazil. In a 2x2 design, measurement invariance of a latent TCP g-factor is further shown to largely hold across combinations of verbal vs. visual dynamic instruction and tablet-based vs. paper & pencil assessment. For the target TCP version (tablet and dynamic visual instruction), only one subtest is found to present increased residual variance and thus needs revision. Overall, a strong association of the TCP with criterion measures (educational achievement and a well-established test of cognitive ability) is found across samples. Measurement of a latent TCP factor could further be shown to be invariant across students with differential opportunity to learn. No strong evidence of biased measurement is found for students with different language backgrounds and socio-economic status. The Test of Cognitive Potential proofs to be a valid and reliable tool for the measurement of general cognitive ability. It will be particularly useful for the evaluation of children with limited understanding of the local language. Avoiding language bias, the TCP may contribute to the reduction of inequalities in educational opportunities that are produced by structural characteristics of many school systems. [less ▲]

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See detailWissensgenerierung in Hybriden Foren: Dargestellt am Beispiel der Erstellung von Sozialindikatoren in internationalen Arbeitsgruppen
Decieux, Jean Philippe Pierre UL

Doctoral thesis (2016)

In modern knowledge societies, knowledge is increasingly co-produced in hybrid fora. Actors from heterogeneous contexts and social positions with different competences come together to discuss, negotiate ... [more ▼]

In modern knowledge societies, knowledge is increasingly co-produced in hybrid fora. Actors from heterogeneous contexts and social positions with different competences come together to discuss, negotiate and finally solve problems with real-life applications. The main goal of such a hybrid forum is to negotiate a common solution for very specific problems. <br />To date, little attention has been paid within sociology to this manner of common knowledge production in hybrid fora. Given the rise in popularity of hybrid fora, there is a need for empirical data. Addressing this need and filling this gap is a major goal of this thesis. Using the example of the construction of a specific set of quantitative Social Indicators, two case studies which illustrate how knowledge is co-produced in a hybrid forum will be presented. <br />Case Study I reconstructs the indicator production within an expert group of the European Commission. This group can structurally be characterized as a hybrid forum consisting of heterogeneous actors. The mission of this group is to create a set of indicators, namely the „European Dashboard on Youth Indicators“. This set of indicators is used as an information source for the promotion of evidence-based-policy-making for EU-Policy. This case study illustrates the structures and processes within a hybrid forum, reflecting the formative factors in the process and shows the final outcome of the indicator creation process. The analysis of this complex process highlights how the different perspectives of the stakeholders evolve and influence each other and which factors and conditions determine the decisions for the final integration of an indicator into the indicator system. This study also analyses which criteria are reflected in this hybrid context to evaluate the indicators and their consequences for practical use in different contexts of interest and application. <br />Case Study II builds on the results of Case Study I and reflects the possibilities, the potential and limitations of the practical application of the European Dashboard on Youth Indicators within the youth reporting system in Luxembourg. <br />The findings of these case studies provide a detailed and empirically grounded picture of factors influencing the indicator production within an expert group and the consequences for the alignment within a real-life application. Within the context of a rising awareness of the conditions of hybrid knowledge production, the results of these studies do not only offer a novel contribution for the perspective of the sociology of knowledge and research methodology, but also offer specific recommendations for the establishment of adequate contexts and structures for hybrid knowledge production in the context of practical applications. [less ▲]

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See detailELECTRODEPOSITION AND SELENIZATION OF METALLIC THIN FILMS FOR KESTERITE SOLAR CELLS APPLICATION
Crossay, Alexandre Jean Arnaud UL

Doctoral thesis (2016)

Thin films of Kesterite Cu2ZnSnSe4 (CZTSe) are prepared via a low energy cost and high material efficiency process, to be potentially used as light absorbers in solar cell devices. The fabrication process ... [more ▼]

Thin films of Kesterite Cu2ZnSnSe4 (CZTSe) are prepared via a low energy cost and high material efficiency process, to be potentially used as light absorbers in solar cell devices. The fabrication process involves two main steps: (i) formation of a metallic stack of Cu/Sn/Zn by sequential electrodeposition of Cu, Sn and Zn onto glass/Mo substrates; (ii) reactive annealing at 550°C in presence of Se and SnSe powders to form Kesterite. This thesis mainly aims at understanding the mechanisms of metal alloying and selenization occurring during step (ii), and their effects on the microstructure of the final film, the presence of secondary phases and their distribution in the thin films synthesized. The second objective is to understand their effects on the solar cells parameters. The stoichiometry of the precursor layers Cu/Sn/Zn is deliberately chosen to be Cu-poor and Zn-rich (Cu/(Zn+Sn)<1 and Zn/Sn>1), as it allows to reach the best power conversion efficiencies. Under these conditions, Kesterite, SnSe2 and ZnSe are expected. However, a study of different compositions shows that the predominant phases present are only Kesterite and ZnSe. SnSe2 is not present because this phase is unstable under the conditions of selenization, which leads to a self-regulation of tin content via gas phase exchange of SnSe during the selenization. Analyses of the selenization of Cu/Sn/Zn layers at short times and lower temperatures allow to deconstruct the mechanism of Kesterite formation into sequential steps. Because of the diffusion of metals and the formation of alloys, a reorganization of metals is observed in the thin films. The layers are then composed of Sn, Cu-Sn and Cu-Zn phases mainly, which are found to be segregating at large scales of tens of micrometers. During selenium incorporation, a tin self-regulation process is established, in which tin is depleted during the first stages of selenization, and then tin is replenished. ZnSe segregates at the surface of the absorber layer as large islands of 10-20 micrometers. By analyzing a specific position of a sample after the different process steps, it is shown that the segregation of ZnSe at this large scale is originating in the segregation of metals during alloying. Because of the presence of ZnSe on the surface of the films, part of the photocurrent generated in the absorber layer is not collected, which decrases the short circuit current of the devices. In this sense, a linear decrease of short circuit current is observed when the ZnSe molar ratio is increasing, and confirmed by external quantum efficiency (EQE) measurements showing a decrease of current collected through the whole range of photon energies. An optimal molar ratio of ZnSe/(CZTSe + ZnSe)=0.2 is found. Below this value, the short circuit current decreases, probably due to the formation of other types of harmful secondary phases such as Cu2SnSe3 or Cu2Se. A strong decrease of open circuit voltage and fill factor of the solar cells is proved to be related to the formation of blisters in the thin films, which result in the creation of pinholes due to their fragility. Formation of these blisters is supposed to originate from hydrogen evolution under the Cu layer during the electrodeposition process. Finally, a study of an additional process of prealloying between the steps of electrodeposition and selenization is presented, which demonstrates the possibility to increase the open circuit voltage of the solar cells by varying the time of this alloying step. A best power conversion efficiency of 7.2% is achieved via this method, which is close to the highest value of 9.1% reported for an electrodeposition-based process of Kesterite synthesis. [less ▲]

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See detailThe role of self-regulatory capacity in the adaptation to pain
Rost, Silke UL

Doctoral thesis (2016)

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See detailGuarding the Guardians. Essays on Audit Regulation
Löhlein, Lukas UL

Doctoral thesis (2015)

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See detailCOMPOSITION AND INTERFACE STUDY OF Cu2ZnSnSe4 BASED SOLAR CELLS
Mousel, Marina UL

Doctoral thesis (2015)

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See detailEnergy-Efficient Driver Assistance System for Electric Vehicles Using Model-Predictive Control
Schwickart, Tim Klemens UL

Doctoral thesis (2015)

This thesis investigates a method to save energy and thus also extend the range of a series-production battery electric vehicle by influencing the driving style automatically with the help of a of a ... [more ▼]

This thesis investigates a method to save energy and thus also extend the range of a series-production battery electric vehicle by influencing the driving style automatically with the help of a of a cruise controller. An exploration of existing methods shows that the contextual consideration of the current and upcoming driving situation is necessary to realise safe and energy-efficient driving. This limits the appropriate approaches to online methods using updated predictions of the vehicle behaviour. It turns out that the most suitable method for the intended purpose is model-predictive control (MPC). The MPC generates controls for the accelerator pedal of the vehicle based on optimised predictions of the vehicle motion and energy consumption subject to the current and future road slope, curvature, speed limits and distance to an eventually preceding vehicle. The non-linear nature of the vehicle dynamics generally necessitates the use of a non-linear prediction model and solving a non-linear optimisation which goes along with difficulties in the online real-time implementation. However in this work - by exploiting and extending the tool sets of classical MPC - a controller based on a quadratic optimal control problem with linear constraints can be formulated that approximates the nonlinearities of the plant dynamics with equivalent accuracy as a non-linear formulation. A linear prediction model of the vehicle motion is derived by a change of the model domain from time to position and a change of variables to predict the kinetic energy of the moving vehicle instead of the driving speed. Further, a convex piece-wise linear energy consumption model is included in the inequality constraints of the problem according to the methodology of separable programming to capture the consumption characteristics of the vehicle in different operating points. In this form, real-time capability and the energy-saving potential of the presented control approach can be demonstrated by simulations of the closed loop and by implementing the controller for driving experiments. A Smart ED series-production battery electric vehicle is chosen for the practical tests and all models and parameters are identified and adapted to the characteristics of the car. In this application case, a significant energy-saving potential could be demonstrated compared to human drivers. To further reduce the computational burden and speed up the computation, the so-called move blocking method for input parameterisation of the MPC control trajectory is investigated and extended within this work to a flexible move blocking approach which enables a fast computation and at the same time high tracking performance. [less ▲]

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See detailImproved Predictions for Geotechnical Vibrations
Macijauskas, Darius UL

Doctoral thesis (2015)

In urban areas where the infrastructure is dense and construction of new structures is near existing and sensitive buildings, frequently vibrations, caused by human activities, occur. Generated waves in ... [more ▼]

In urban areas where the infrastructure is dense and construction of new structures is near existing and sensitive buildings, frequently vibrations, caused by human activities, occur. Generated waves in the soil may adversely affect surrounding buildings. These vibrations have to be predicted a priori by using currently available knowledge of the soil dynamics. Current research, conducted by Deltares research institute, showed that the reliability of methods for prediction of man-made vibrations is disappointingly low. Therefore the models for vibrations in the soil should be improved in order to get more accurate predictions. The main aim of this thesis is to increase the knowledge on dynamic soil behaviour with respect to the fundamental geotechnical aspects of the soil, like non-viscous damping, inhomogeneity, anisotropy, variable degree of saturation, etc. and to give an improved prediction method. The scientific investigations of this thesis started with the following setup: an oscillating plate on an elastic, homogeneous and isotropic half-space, where the plate oscillates harmonically in vertical direction and the soil is unsaturated. In this way, the geotechnical aspects have been left aside in order to check first whether it is possible to predict the vibration amplitudes of the oscillating plate and of the soil surface, without additional complexities. This setting allowed to compare the present analytical methods with the results, obtained from the finite element method (FEM) calculations, and showed that the analytical methods have their limitations. Therefore the wave-field near an oscillating plate had to be investigated more carefully. Unfortunately the state of the art in soil dynamics is such that only the particle vibration velocities are measured without knowing which part of the velocities/vibrations belongs to which type of basic wave (compressional, shear or Rayleigh wave). Therefore first of all, a technique to decompose the measured signal into its basic waves was developed. This new technique showed remarkably that all three basic waves have phase shifts and these phase shifts are all different from each other. The decomposition technique is an important tool for researching soil dynamics. Also a qualitative evaluation of the energy transmission between the basic waves near the vibration source was given, which showed that the R-wave energy starts at zero just at the source and grows in the near-field zone due to an energy transmission (body waves are transferring energy to the R-wave). This means that even without uncertainties in the soil body, there is a lack of understanding of the behaviour of the different waves. A real field test is performed with a shaker on a soft peaty site in the Netherlands, as an attempted to replicate the FE model experiments. It showed the limitations of the analytical methods and highlighted the indispensability of the FEM. Still, for engineering purposes, an improved analytical method is suggested, which is able to predict the geotechnical vibrations with good accuracy. Herein, one of the fundamental aspects, the material damping, was used and a hypothesis was made, that with a more correct physical model of the soil material damping, the vibration predictions with FEM can be improved. The 1D frictional damping model, first suggested by Van Baars (2011), was extended for the 3D and incorporated into the FEM software Plaxis as a User Defined Soil Material model. The results are very interesting scientifically, but do not give much better results as the already existing Rayleigh damping model. [less ▲]

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See detailDistribution Network Line Protection in the Presence of Distributed Generation
Margossian, Harag UL

Doctoral thesis (2015)

The evolution of the distribution network from a passive grid with unidirectional power flows to, in the presence of distributed generation (DGs), an active grid with bidirectional power flows can lead to ... [more ▼]

The evolution of the distribution network from a passive grid with unidirectional power flows to, in the presence of distributed generation (DGs), an active grid with bidirectional power flows can lead to some technical challenges in its operation as well as some opportunities for greater control and grid support. This dissertation studies the impact of high levels of penetration of DGs into the power system on the operation of distribution network line protection. The contribution of DGs during faults results in varying short circuit current levels that are hard to predict. This complicates the design of distribution network line protection. If the DGs are located in between the protection device and the fault, the device sees a lower current than it would see in the absence of the DGs. Conversely, if they are connected upstream of the device, the device sees a higher current than before. This means that the reliability, selectivity and speed of the protection devices can be negatively or positively affected. This dissertation analyzes what can be expected from the DGs and how the protection devices themselves can be enhanced in order to avoid these potential problems. In the planning stage, it is possible to control the outputs of DGs during faults in a way that enhances the operation of the protection devices instead of hampering it. This can be done by enforcing regulations through distribution network grid codes. There are two main grid code requirements that directly impact the fault current levels in the network: fault ride through requirements that specify how long and for what voltages the DGs need to remain connected and dynamic voltage support curves that regulate their reactive current output during faults. From these requirements, three parameters are of particular interest: the voltage threshold above which the DGs need to remain connected, the maximum current that they should be capable of producing and the maximum reactive current that they are required to produce below a certain voltage. Using these three parameters, it is possible to control the fault current levels in the network and consequently increase the maximum amount of DGs that can be connected, without endangering the operation of the protection system. In the operating stage, it is possible to enhance the protection devices themselves so that they can deal with the varying fault current levels. Here, adaptive protection is considered. By gathering information about the changes in the network, including the status of switches and DGs and changing the settings of the protection relays accordingly, the reliability, selectivity and speed of the protection system can be maintained while increasing its complexity and cost. To get the information needed from the network, a modified state estimation is proposed. The distribution network is characterized by low observability due to the low number of measurements available. For this reason, load estimates and zero injection buses are added as measurements. To account for the additional uncertainty introduced by the presence of DGs, information about the DGs and their controls are used to add additional measurements that support the state estimation. When calculating the fault current levels in the network to choose the protection relay settings, it is important to correctly account for the fault contributions of inverter based DGs that represent a significant proportion of DGs connected to the distribution network. Unlike synchronous and asynchronous generators, inverter based DGs have a controlled current output during faults. By using an iterative process where the outputs of inverter based DGs are changed based on the calculated voltage at their terminals, a more accurate calculation of the short circuit current levels can be made. Employing these methods in the planning and operating stages, it will be possible to increase the amount of DGs that can be connected to the distribution network, while avoiding cascading faults, slower operation times and the unnecessary loss of load associated with protection mal-operation. The methods should be applied in reasonable steps and whenever needed in combination with each other to ensure the practicality of their implementation and to avoid unnecessary costs. [less ▲]

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See detailAnalysis of signal transduction pathways linking L-plastin Ser5 phosphorylation to breast cancer cell invasion
Lommel, Maiti UL

Doctoral thesis (2015)

The organisation of the actin cytoskeleton is regulated by abundant actin-binding proteins. Functional alteration of these proteins contributes to pathologies such as cancer where structural and ... [more ▼]

The organisation of the actin cytoskeleton is regulated by abundant actin-binding proteins. Functional alteration of these proteins contributes to pathologies such as cancer where structural and functional modifications of the actin cytoskeleton are linked to uncontrolled cell motility and signalling. The actin-bundling protein L-plastin has initially been detected in haematopoietic cells where it plays a role in the immune response. L-plastin is also ectopically expressed in several solid tumours and is often considered as a metastatic marker. L-plastin is known to be phosphorylated in vitro and in vivo with residue serine 5 (Ser5) being the major phosphorylation site. Ser5 phosphorylation increases the F-actin-binding and -bundling activity of L-plastin and regulates actin turn-over. Recent findings demonstrate that L-plastin Ser5 phosphorylation is crucial for invasion and metastasis formation. This research work has unravelled the signalling pathways leading to L-plastin Ser5 phosphorylation in breast cancer cells. Previously, protein kinase A, protein kinase C and phosphoinositide-3-kinase have been reported to play a role in L-plastin Ser5 phosphorylation depending on the cell type and environment. This work however reveals that RSK kinases are the predominant kinases responsible for L-plastin Ser5 phosphorylation in breast cancer cells. In vitro kinase assays revealed that RSK1 and RSK2 are able to directly phosphorylate L-plastin on Ser5 and a whole genome microarray analysis pointed to an involvement of the ERK/MAPK pathway in this event. The involvement of this pathway was consolidated by activation and inhibition studies as well as by siRNA-mediated knockdowns. To our knowledge, this is the first evidence that L-plastin Ser5 phosphorylation occurs via the downstream ERK/MAPK pathway kinases, RSK1 and RSK2. Moreover, a computational modelling approach enabled us to show that RSK is the most important activator of L-plastin in breast cancer cell lines compared to other previously identified kinases. We performed migration and invasion assays which showed that RSK knockdown, besides reducing L-plastin Ser5 phosphorylation, also impaired breast cancer cell migration and invasion. The identification of a novel substrate of RSK kinases whose phosphorylation is important for cancer cell invasion underlines the importance of RSK in cancer progression and highlights RSK as a promising drug target in certain invasive carcinomas. [less ▲]

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See detailDIFFERENTIAL EFFECTS OF IL-6-TYPE CYTOKINES, THEIR INTERPLAY WITH HYPOXIA AND RESULTING EFFECTS ON THE METABOLISM
Zimmer, Andreas David UL

Doctoral thesis (2015)

IL-6-type cytokines signal mainly via the Jak/STAT pathway using the common receptor chain gp130. They are implicated in various biological processes such as differentiation, apoptosis, tissue ... [more ▼]

IL-6-type cytokines signal mainly via the Jak/STAT pathway using the common receptor chain gp130. They are implicated in various biological processes such as differentiation, apoptosis, tissue regeneration and proliferation. However, one of their main functions is the regulation of inflammatory processes, especially the initial induction of an inflammatory response. They hereby exert key steps in the onset as well as in the termination of an inflammation and in the promotion of the shift from the innate to the adaptive immune response. In hepatocellular carcinoma (HCC) IL-6 has been identified as a key factor in the onset as well as in the progression of this cancer. In this study we first investigated the effects of the IL-6-type cytokine IL-27 on hepatic cells. By evaluating IL-27 signalling in several HCC cell lines as well as hepatic cells, we could demonstrate that IL-27 does, in contrary to other IL-6-type cytokines, activate STAT1 and STAT3. A transcriptional and protein read-out of STAT3 was not found in hepatic cells. Thus, IL-27 exerts interferon γ-like functions only in the liver. Interestingly, we could further show that the IL-27 signalling can still be repressed by the canonical IL-6-type cytokine feedback regulator SOCS3, following a pre-stimulation with other IL-6-type cytokines. The second part of this thesis focused on the effects of the IL-6-type cytokine Oncostatin M (OSM) on the cellular metabolism. We hereby evaluated to which extent OSM-mediated STAT3 activation can induce a Warburg-like, highly glycolytic, metabolic phenotype under normoxia. OSM induced the expression of HIF-1α, a key factor mediating the shift to a highly glycolytic phenotype, in several HCC cell lines and immortalized hepatocytes. In the non-neoplastic hepatocyte cell line, PH5CH8, this led to the induction of a more glycolytic metabolic phenotype. The observed changes in these immortalized hepatocytes did not fully resemble the metabolic state seen under hypoxia, since mainly the observed induction of PDK1 seems to explain the effect. Overall we could not observe strong effects on glycolytic enzymes or other canonical HIF-1α target genes involved in metabolism, on a transcriptional or protein expression level in the investigated cells. Interestingly we found that HIF-1α does not seem to be mediating all the early adaptions of the cellular metabolism to hypoxia. The early inhibition of the pyruvate dehydrogenase complex could be shown to be independent of the HIF-1α-mediated up-regulation of the pyruvate dehydrogenase kinase 1, but might rather be induced by reactive oxygen species, created during the switch from normoxia to hypoxia. In summary we could show that in the liver IL-27 exerts interferon γ-like effects. Additionally, cytokine-activated STAT3 does not per se induce a glycolytic metabolic phenotype and HIF-1α is not necessary for some of the early adaptions of the cellular metabolism to hypoxia. [less ▲]

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See detailELECTRICAL CHARACTERIZATION OF KESTERITE THIN FILM ABSORBERS AND SOLAR CELLS
Weiss, Thomas UL

Doctoral thesis (2015)

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See detailKonstruktvalidität des Komplexen Problemlösens unter besonderer Berücksichtigung moderner diagnostischer Ansätze
Kretzschmar, André UL

Doctoral thesis (2015)

This thesis addresses the question whether Complex Problem Solving (CPS) could be seen as a distinct cognitive ability construct that is not considered sufficiently in the context of established theories ... [more ▼]

This thesis addresses the question whether Complex Problem Solving (CPS) could be seen as a distinct cognitive ability construct that is not considered sufficiently in the context of established theories of intelligence. For this purpose, an introduction into the research field of CPS is provided in the first part of this thesis (chapter 1). It is shown that CPS research has always been strongly influenced by the quality of the assessment tools. Therefore, to evaluate whether CPS is an independent construct requires a particular emphasis on the quality of the CPS assessment tools. Consequently, the second part of this work deals with the assessment of CPS. In chapter 2, the general challenges for CPS assessment as well as important advantages and disadvantages of contemporary CPS assessment tools (using the example of MicroDYN) are discussed. In chapter 3, the development and first empirical results of a new CPS assessment tool called MicroFIN are presented. Chapter 4 covers a particular relevant topic of computer-based CPS assessment: the influence of ICT literacy (i.e. the competence in using computers) on specific CPS assessment tools. For this purpose, the impact of ICT literacy on MicroDYN performance is examined in three different samples (N1 = 222, N2 = 341, N3 = 389). In addition, based on a sample of a pilot study (N = 91) the influence of ICT literacy on MicroFIN performance is presented. The results indicate that the impact of ICT Literacy appears neither for MicroDYN nor for MicroFIN as a threat of test validity. The third part of this work covers the central question of this thesis, that is whether CPS could be seen as a distinct cognitive ability construct that is independent of established intelligence constructs. Therefore, several criteria for an independent ability construct are discussed in chapter 5. Taking current research findings for CPS into account, open research questions for the assumption of a distinct CPS construct are examined in two empirical studies. Study 2 (chapter 6; N = 1908) focuses on the incremental validity of CPS beyond verbal reasoning in explaining the variance of school grades. For the first time in current CPS research, additional predictors for school grades (i.e. school competencies) in the mathematical and the reading domain are considered. The results indicate an incremental validity of CPS in the mathematical, but not in the reading domain. In addition, the study provides evidence that the incremental validity of CPS holds only to a small degree if relevant predictors of school grades are simultaneously taken into account. In study 3 (chapter 7; N = 227), the validity of CPS is examined with a comprehensive operationalisation of several intelligence constructs. The results indicate evidence for convergent and discriminant validity. Consequently, CPS could be seen as a specific cognitive ability that is less covered by traditional intelligence tests. With regard to the incremental validity of CPS, evidence for a statistical prediction of school grades beyond established intelligence constructs is only found for a specific, but not for a construct-representative operationalisation of intelligence. In chapter 8, an alternative interpretation of the specific CPS variance is discussed. Based on that interpretation, which has not been considered in CPS research yet, CPS can be seen as a specific content facet of cognitive tasks, but not as an independent cognitive ability. In the last part of this thesis (chapter 9), the findings and considerations concerning the assessment and construct validity of CPS are summarized. Considering current CPS assessment tools and the results for MicroFIN, research questions that are still open and the potential for future CPS assessment are presented. Furthermore, the findings from study 2 and 3 are reviewed with regard to the criteria for an independent ability construct. Finally, the assumption of a distinct CPS construct in the nomological network of intelligence is evaluated. Although further research is needed to clarify this issue, currently the assumption of a distinct CPS construct independent from established intelligence constructs does not seem justified. [less ▲]

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See detailEFFECT OF TRANSMISSION TARIFFS ON INVESTMENTS IN CONVENTIONAL AND RENEWABLE POWER GENERATION, STORAGE AND TRANSMISSION IN THE COUPLED PAN- EUROPEAN DAY-AHEAD MARKET FRAMEWORK
Bilibin, Ilya UL

Doctoral thesis (2015)

This work examines how electricity transmission tariffs influence the composition of the future power plants fleet. Transmission tariffs are classified and an optimization model of power markets and ... [more ▼]

This work examines how electricity transmission tariffs influence the composition of the future power plants fleet. Transmission tariffs are classified and an optimization model of power markets and investors profit maximization is suggested. The work finds that transmission tariffs do influence investment decisions, though this influence is not large. [less ▲]

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See detailOn the behaviour of shear stud connections in composite beams with deep decking
Nellinger, Sebastian UL

Doctoral thesis (2015)

Steel-concrete composite construction has many advantages for the construction of multistorey buildings. The use of composite beams acting compositely with the floor slab achieves longer spans and reduces ... [more ▼]

Steel-concrete composite construction has many advantages for the construction of multistorey buildings. The use of composite beams acting compositely with the floor slab achieves longer spans and reduces the weight of the beams. The weight reduction can be further improved by replacing the solid concrete slab with a steel-concrete composite slab using steel decking. However, using composite slabs reduces the shear forces that are transferred between the slab and the beam. This is because the number of studs in the span is limited by the deck geometry. In addition, the load-bearing behaviour of studs in the ribs of composite slabs is different to studs in solid slabs and shows typically a reduced resistance per stud. Currently, [DIN EN 1994-1-1, 2010] applies an empirical reduction factor to the resistance of studs in solid slabs to analyse the resistance of studs in the ribs of composite slabs. A comparison to push-out test results shows that this formulae results in an unsatisfactory correlation. Furthermore, the reduction factor is unsafe in many cases with modern decking. The latest empirical reduction factors in [Konrad, 2011] are currently discussed as alternative to the rules of [DIN EN 1994-1-1, 2010]. They show a significantly improved correlation to test results and an increased field of application. A significantly higher correlation to test results is obtained with the mechanical model by [Lungershausen, 1988]. Because of the restrictive field of application and missing parameters, like the concrete strength, it is not discussed as replacement for the reduction factors. A newly conducted series of push-out tests with modern deep steel decking shows the insufficiency of the presented analysis methods of the stud shear resistance, as the predictions were in general non-conservative. Furthermore, depending on the geometry of the shear connection, a new failure mode was observed: Rib pry-out failure. Investigation on concentric and eccentric transverse loading of push-out specimens, to consider the loading conditions of a real slab, show in general beneficial influences on the load-slip behaviour. Based on the behaviour of the studs in push-out tests, equations for the shear connector resistance based on the failure modes are developed. A combined bending failure of the shear stud and the concrete rib is assumed. The observed failure modes in the tests are considered by different yield-lines of the shear stud. The shear resistance of the pure stud gives the upper bound for the shear connector resistance. The new equations show a good correlation to test results and are safe for modern types of steel decking. In comparison to [DIN EN 1994-1-1, 2010], the field of application is extended by the stud position, as in [Konrad, 2011], and deeper decking, as in [Lungershausen, 1988]. The analysis of the bending resistance of two accompanying beam tests confirms the accuracy of the new shear stud resistance. The beam tests have very low degrees of shear connection. The end-slip at ultimate load exceeds the limiting slip of 6mm, but at 95% of ultimate load the limiting slip is satisfied. A numerical model for composite beams is verified against the test results. The model considers the shear studs as non-linear springs. A simplified load-displacement curve is presented and verified against real load-slip curves. [less ▲]

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See detailViva vox iuris - oder die juridische Stimme der Literatur. Kafkas Der Proceß und Hoffmanns Der Sandmann im Spiegel der dogmatischen Anthropologie Pierre Legendres
Becker, Katrin UL

Doctoral thesis (2015)

The doctoral dissertation “Viva vox iuris” is aimed at extending the research on law and literature by developping a new perspective, based on Pierre Legendre’s “dogmatic anthropology”. Starting with an ... [more ▼]

The doctoral dissertation “Viva vox iuris” is aimed at extending the research on law and literature by developping a new perspective, based on Pierre Legendre’s “dogmatic anthropology”. Starting with an overview of the current state of research in this field, and based on a detailed presentation of Legendre’s theory, the dissertation develops the hypothesis that the deep entanglement of law and literature confers upon literature the capacity of either reinforcing the effectivity of cultural normativity, or of influencing it in the sense of a modificatory force. The plausibility of this hypothesis is then assessed by a thorough analysis of Kafka’s The Trial and Hoffmann’s The Sandman. The Trial is presented as being a novel that stages the failure of interpretation on the diegetic, hermeneutic as well as the production level, i.e. with regard to the author (– interpretation being, from Legendre’s perspective, the fundamental cultural technique assuring a non-delusional human existence). Being confronted with this failure and the consequent lack of a regime of sense, the reader gains insight, ex negativo, into the necessity of being inscribed, by way of interpretation, into an order of Reference that needs to be mediated by literature and law. With regard to The Sandman, the dissertation undertakes to show, through a combination of the concept of testimony with the dogmatic-anthropological core concepts of alterity and representation, how the fantastical blurring of the limits between reality and fiction, as staged in the novel, provides insights into the contingency of the fundamental structure of the normative order of cultural and subjective identity. [less ▲]

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See detailAstrophysical aspects of dark matter direct detection
Magni, Stefano UL

Doctoral thesis (2015)

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See detailNON-CONTRACTUAL LIABILITIES FROM CIVILIAN VERSIONS OF GNSS: CURRENT TRENDS, LEGAL CHALLENGES AND POTENTIAL
Loukakis, Andreas UL

Doctoral thesis (2015)

Galileo is to be Europe’s own Global Navigation Satellite System (GNSS). It is expected to provide a highly accurate, guaranteed global positioning service under civilian control. It will be interoperable ... [more ▼]

Galileo is to be Europe’s own Global Navigation Satellite System (GNSS). It is expected to provide a highly accurate, guaranteed global positioning service under civilian control. It will be interoperable with the Global Positioning System (GPS), the US version of GNSS. Remarkably enough, whereas GPS was introduced as a purely military system, Galileo will be the first solely civilian GNSS, offering a great number of useful -everyday life- applications. It is expected to become fully operational by the year 2020 as part of Horizon 2020, the EU’s funding program for research and innovation. For the operation of Galileo, advanced technology will need to be employed. A number of satellites will be placed into fixed orbits in outer space; the satellites will be constantly emitting navigational signals indicating their position at any given time and in a very precise way. The navigational signals will be received by any person possessing the necessary technology, such as a GNSS receiver (the so-called navis technology). When receiving the signals from at least four satellites, the receiver can accurately pinpoint the position of persons and goods around the globe. There will be many benefits in using this technology, such as more efficient navigation of different modes of transportation (i.e. navigation of planes or ships). Besides navigational data, Galileo satellites will provide information for timing and positioning. Hence, various applications concerned with the synchronization of economic networks (i.e. at banks or financial institutions) or scientific applications related to the environment and meteorology are expected to emerge. Nonetheless, where there are advantages, there are also risks and legal challenges. Questions relating to the civil liability of the Galileo’s system operator in the event of a GNSS failure -especially liabilities connected to signal provision in space- have attracted significant interest lately. For example, a failure in signal provision (i.e. signal loss or an erroneous signal) resulting from negligence with respect to the GNSS operator may lead to damage scenarios with catastrophic consequences: an aircraft crash in a densely populated area, or a shipwreck with disastrous effects for the environment would be two examples. Following these observations, several questions must be asked from a liability law perspective. Inter alia: what are possible civil liability implications emanating from the advent of civilian versions of GNSS such as the EU’s Galileo? Can the provision of defective information from signals lead to liability implications? What would be the responses under current legal provisions? And lastly, what need may arise in the future for the initiation of a centralized approach, for instance a unified instrument, either at EU or international level, regulating liabilities for the signal in space provision? Interestingly enough, once the first GNSS structures such as the US GPS or Russian GLONASS became operational, the issue of liability from a signal failure was not of such significant concern in light of their mostly military nature. Presently, the situation has changed to an important extent: due to the advent of new non-military versions such as Galileo, the issue of liability connected to the provision of navigational signals has become topical. This research aims at examining the foregoing questions related to civil liability implications (mainly non-contractual liabilities) from the perspective of civilian versions of GNSS. The EU’s Galileo will be the most prevailing example examined in the present study. The research attempts to investigate the civil liability ramifications especially from the GNSS-Galileo operator’s perspective. Since the governance issues surrounding the operation of Galileo are still subject to debate, the research features two hypothetical case studies: on the one hand, a public governance scheme with the EU operating the system and possible liabilities against the EU, and on the other hand, a private governance scheme with a private entity operating the system and potential liabilities towards the private operator. Both case studies are examined from a de lege lata and a de lege ferenda perspective. Yet, the present research attempts to identify some future proposals. As it is argued, the issue of GNSS liability should be first regulated at regional level rather than international level. In this respect, the EU could, for example, possibly promote a future EU Regulation. Moreover, and as established by the analysis of the present study, such a Regulation should contain two elements, a substantive and procedural one. For the resolution of disputes connected to signal provision in space, the rule of strict liability and liability channeling onto the operator from a substantive viewpoint may depict the peculiarities contained within the field of satellite navigation more efficiently. Most importantly, and as far as the resolution of such disputes is concerned, this study argues that binding arbitration may be a plausible and alternative option to be considered in the foreseeable future. To this end, certain inspirations can potentially be drawn by the new PCA Rules of Arbitration on Outer Space Disputes adopted recently in December 2011. [less ▲]

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See detailLightweight Public-Key Cryptography for Wireless Sensor Nodes
Liu, Zhe UL

Doctoral thesis (2015)

This thesis studies techniques for the efficient implementation of public-key cryptography on resource-constrained computing devices such as wireless sensor nodes. We focus on three different families of ... [more ▼]

This thesis studies techniques for the efficient implementation of public-key cryptography on resource-constrained computing devices such as wireless sensor nodes. We focus on three different families of public-key cryptosystems, namely RSA, elliptic curve schemes (e.g. ECDH), as well as a lattice-based encryption algorithm using the ring variant of the Learning With Errors problem (Ring-LWE). In the context of efficient RSA implementation, this thesis first describes the Reverse Product Scanning (RPS) technique for multi-precision multiplication and squaring on 8-bit AVR processors. Then, we analyze and compare six algorithms for software implementation of Montgomery multiplication and shed some new light on the relative performance of the different variants. Finally, we present a highly-optimized 1024-bit RSA software that achieves record-setting execution times on 8-bit ATmega processors thanks to a combination of sophisticated implementation options including the Chinese Remainder Theorem (CRT), the m-ary exponentiation method, as well as the RPS multiplication technique. The main contribution of this thesis lies in the area of Elliptic Curve Cryptography (ECC), where we describe three different implementations for wireless sensor nodes equipped with 8 and 16-bit processors. First, we present several techniques to improve the performance of prime-field arithmetic operations (e.g. optimized operand caching, sliding block doubling, and Karatsuba block squaring) and report the fastest implementation of key exchange and signature generation/verification based on the NIST P-192 curve. Second, we introduce an efficient yet highly-regular library for arithmetic in Optimal Prime Fields (OPFs) and propose a novel approach for the implementation of ephemeral ECDH key exchange that exploits the birational equivalence of Montgomery and twisted Edwards curves. Third, we describe an algorithm for the generation of so-called MoTE curves that allows one to use the fastest formulae for point addition/doubling in both the Montgomery form and the twisted Edwards form. Finally, we describe efficient ECC implementations for 159 and 191-bit MoTE curves that achieve record-setting execution times for scalar multiplication on a 16-bit MSP430 processor. The third part of this thesis deals with the efficient implementation of Ring-LWE encryption and proposes novel approaches to speed up the Number Theoretic Transform (NTT) used for polynomial multiplication. Our contributions in this area include the Move-and-Add (MA) method for coefficient multiplication, the Shift-Add-Multiply-Subtract-Subtract (SAMS2) technique for modular reduction, and an optimized variant for Montgomery multiplication. Furthermore, we describe an optimized coefficient storage method to minimize the RAM footprint of NTT multiplications. Finally, we propose a special byte-scanning technique to reduce the execution time of discrete Gaussian sampling based on the Knuth-Yao random walk algorithm. [less ▲]

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See detailCollusions and Privacy in Rational-Resilient Gossip
Decouchant, Jérémie UL

Doctoral thesis (2015)

Gossip-based content dissemination protocols are a scalable and cheap alternative to centralized content sharing systems. However, it is well known that these protocols suffer from rational nodes, i.e ... [more ▼]

Gossip-based content dissemination protocols are a scalable and cheap alternative to centralized content sharing systems. However, it is well known that these protocols suffer from rational nodes, i.e., nodes that aim at downloading the content without contributing their fair share to the system. While the problem of rational nodes that act individually has been well addressed in the literature, colluding rational nodes is still an open issue. In addition, previous rational-resilient gossip-based solutions require nodes to log their interactions with others, and disclose the content of their logs, which may disclose sensitive information. Nowadays, a consensus exists on the necessity of reinforcing the control of users on their personal information. Nonetheless, to the best of our knowledge no privacy-preserving rational-resilient gossip-based content dissemination system exists. The contributions of this thesis are twofold. First, we present AcTinG, a protocol that prevents rational collusions in gossip-based content dissemination protocols, while guaranteeing zero false positive accusations. AcTing makes nodes maintain secure logs and mutually check each others’ correctness thanks to verifiable but non predictable audits. As a consequence of its design, it is shown to be a Nash-equilibrium. A performance evaluation shows that AcTinG is able to deliver all messages despite the presence of colluders, and exhibits similar scalability properties as standard gossip-based dissemination protocols. Second, we describe P AG, the first accountable and privacy-preserving gossip pro- tocol. P AG builds on a monitoring infrastructure, and homomorphic cryptographic procedures to provide privacy to nodes while making sure that nodes forward the content they receive. The theoretical evaluation of P AG shows that breaking the privacy of interactions is difficult, even in presence of a global and active opponent. We assess this protocol both in terms of privacy and performance using a deployment performed on a cluster of machines, simulations involving up to a million of nodes, and theoretical proofs. The bandwidth overhead is much lower than existing anonymous communication protocols, while still being practical in terms of CPU usage. [less ▲]

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