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See detailContributions to the asymptotic study of Hermite driven processes
Tran, Thi Thanh Diu UL

Doctoral thesis (2018)

This thesis consists of two parts. Part I is an introduction to Hermite processes, Hermite random fields, Fisher information and to the papers constituting the thesis. More precisely, in Section 1 we ... [more ▼]

This thesis consists of two parts. Part I is an introduction to Hermite processes, Hermite random fields, Fisher information and to the papers constituting the thesis. More precisely, in Section 1 we introduce Hermite processes in a nutshell, as well as some of its basic properties. It is the necessary background for the articles [a] and [c]. In Section 2 we consider briefly the multiparameter Hermite random fields and we study some less elementary facts which are used in the article [b]. In section 3, we recall some terminology about Fisher information related to the article [d]. Finally, our articles [a] to [d] are summarised in Section 4. Part II consists of the articles themselves: [a] T.T. Diu Tran (2017): Non-central limit theorem for quadratic functionals of Hermite-driven long memory moving average processes. Stochastic and Dynamics, 18, no. 4. [b] T.T. Diu Tran (2016): Asymptotic behavior for quadratic variations of nonGaussian multiparameter Hermite random fields. Under revision for Probability and Mathematical Statistics. [c] I. Nourdin, T.T. Diu Tran (2017): Statistical inference for Vasicek-type model driven by Hermite processes. Submitted to Stochastic Process and their Applications. [d] T.T. Diu Tran (2017+): Fisher information and multivariate Fouth Moment Theorem. Main results have already been obtained. It should be submitted soon. [less ▲]

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See detailIntegrating User- and System-Centric Perspectives into Collaborative Compound Document Authoring
Klein, Johannes UL

Doctoral thesis (2018)

Computer-supported collaborative work is increasingly common in our professional and personal life. However, the expectations and requirements of the users are frequently neglected when addressing the ... [more ▼]

Computer-supported collaborative work is increasingly common in our professional and personal life. However, the expectations and requirements of the users are frequently neglected when addressing the technological challenges associated with the development of a distributed collaboration system. The proposed collaboration environment employs an integrative approach to distributed compound document authoring, including both a user- and system-centric perspective on collaborative work. An interruption-free, reliable, and responsive shared work environment with a near real-time representation of the work of others is a core expectation from the users. In order to provide these features, a fine-granular, graph-based data representation has been developed to serve as the basis for this approach. The data representing individual compound document elements is partitioned over sets of three distinct nodes in the graph structure. This separation of metadata and payload data enables the precise attribution of editing operations while maintaining an adaptable and extensible data representation. User-specific preferences allow for the individualization of a user's work environment to account for personal preferences, requirements from the current collaboration scenario, or limitations of the employed computer system. Support for complex, data type-specific editing commands is integrated with a concurrent command application and Layered Consistency Management model. This enables a near real-time representation of the work of others, the preservation of the users' editing intentions, and the maintenance of a globally consistent data state. Intra- and inter-document relations retain semantic connections between distinct data structure elements. Together with an element's supplemental data, this related information enables additional, autonomous conflict resolution approaches and facilitates a comprehensive representation of the conflict in case of a manual resolution process. By integrating these functionalities into one coherent system, the users are provided with an unobtrusive, yet reliable and feature-rich distributed work environment able to actively support collaborative compound document authoring. [less ▲]

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See detailAnalysis of cancer related protein isoforms by mass spectrometry
Ancheva, Lina UL

Doctoral thesis (2018)

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See detailTransforming Time Series for Efficient and Accurate Classification
Li, Daoyuan UL

Doctoral thesis (2018)

Time series data refer to sequences of data that are ordered either temporally, spatially or in another defined order. They can be frequently found in a variety of domains, including financial data ... [more ▼]

Time series data refer to sequences of data that are ordered either temporally, spatially or in another defined order. They can be frequently found in a variety of domains, including financial data analysis, medical and health monitoring and industrial automation applications. Due to their abundance and wide application scenarios, there has been an increasing need for efficient machine learning algorithms to extract information and build knowledge from these data. One of the major tasks in time series mining is time series classification (TSC), which consists of applying a learning algorithm on labeled data to train a model that will then be used to predict the classes of samples from an unlabeled data set. Due to the sequential characteristic of time series data, state-of-the-art classification algorithms (such as SVM and Random Forest) that performs well for generic data are usually not suitable for TSC. In order to improve the performance of TSC tasks, this dissertation proposes different methods to transform time series data for a better feature extraction process as well as novel algorithms to achieve better classification performance in terms of computation efficiency and classification accuracy. In the first part of this dissertation, we conduct a large scale empirical study that takes advantage of discrete wavelet transform (DWT) for time series dimensionality reduction. We first transform real-valued time series data using different families of DWT. Then we apply dynamic time warping (DTW)-based 1NN classification on 39 datasets and find out that existing DWT-based lossy compression approaches can help to overcome the challenges of storage and computation time. Furthermore, we provide assurances to practitioners by empirically showing, with various datasets and with several DWT approaches, that TSC algorithms yield similar accuracy on both compressed (i.e., approximated) and raw time series data. We also show that, in some datasets, wavelets may actually help in reducing noisy variations which deteriorate the performance of TSC tasks. In a few cases, we note that the residual details/noises from compression are more useful for recognizing data patterns. In the second part, we propose a language model-based approach for TSC named Domain Series Corpus (DSCo), in order to take advantage of mature techniques from both time series mining and Natural Language Processing (NLP) communities. After transforming real-valued time series into texts using Symbolic Aggregate approXimation (SAX), we build per-class language models (unigrams and bigrams) from these symbolized text corpora. To classify unlabeled samples, we compute the fitness of each symbolized sample against all per-class models and choose the class represented by the model with the best fitness score. Through extensive experiments on an open dataset archive, we demonstrate that DSCo performs similarly to approaches working with original uncompressed numeric data. We further propose DSCo-NG to improve the computation efficiency and classification accuracy of DSCo. In contrast to DSCo where we try to find the best way to recursively segment time series, DSCo-NG breaks time series into smaller segments of the same size, this simplification also leads to simplified language model inference in the training phase and slightly higher classification accuracy. The third part of this dissertation presents a multiscale visibility graph representation for time series as well as feature extraction methods for TSC, so that both global and local features are fully extracted from time series data. Unlike traditional TSC approaches that seek to find global similarities in time series databases (e.g., 1NN-DTW) or methods specializing in locating local patterns/subsequences (e.g., shapelets), we extract solely statistical features from graphs that are generated from time series. Specifically, we augment time series by means of their multiscale approximations, which are further transformed into a set of visibility graphs. After extracting probability distributions of small motifs, density, assortativity, etc., these features are used for building highly accurate classification models using generic classifiers (e.g., Support Vector Machine and eXtreme Gradient Boosting). Based on extensive experiments on a large number of open datasets and comparison with five state-of-the-art TSC algorithms, our approach is shown to be both accurate and efficient: it is more accurate than Learning Shapelets and at the same time faster than Fast Shapelets. Finally, we list a few industrial applications that relevant to our research work, including Non-Intrusive Load Monitoring as well as anomaly detection and visualization by means for hierarchical clustering for time series data. In summary, this dissertation explores different possibilities to improve the efficiency and accuracy of TSC algorithms. To that end, we employ a range of techniques including wavelet transforms, symbolic approximations, language models and graph mining algorithms. We experiment and evaluate our approaches using publicly available time series datasets. Comparison with the state-of-the-art shows that the approaches developed in this dissertation perform well, and contribute to advance the field of TSC. [less ▲]

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See detailHybrid Histories: Technologies of Memory and the Cultural Dynamics of Home Movies, 1895-2005
van der Heijden, Tim UL

Doctoral thesis (2018)

This dissertation analyses the cultural dynamics of home movies in the twentieth century. It investigates how various generations have recorded their family memories on film, video and digital media, and ... [more ▼]

This dissertation analyses the cultural dynamics of home movies in the twentieth century. It investigates how various generations have recorded their family memories on film, video and digital media, and, more specifically, how changes in these “technologies of memory” have shaped new forms of home movie making and screening. Covering the period from the invention of the film camera in the late nineteenth century, the introduction of 9.5mm, 16mm, 8mm small-gauges and Super 8 film technologies for amateurs, via home video to digital media technologies, this study addresses the complex interrelations between the materiality of film, video and digital media technologies, their social usages and cultural meanings from a long-term historical perspective. Focusing on specific periods of transition, it becomes clear that different media technologies, user practices and discourses not only succeed each other in time, but also increasingly interrelate, interact or even transform each other. Maintaining both a diachronic and a synchronic perspective on media transitions, this dissertation proposes an alternative form of media historiography that rethinks media histories beyond the frameworks of change and continuity by perceiving hybridity as a constant factor in media historical development. [less ▲]

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See detailData Integration for Image Guided Deep Brain Stimulation
Husch, Andreas UL

Doctoral thesis (2017)

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See detailInvestigation of crack development in a fairfaced replacement screed based on fiber-reinforced concrete
Weiler, Michael UL

Doctoral thesis (2017)

In the present study, a design concept for unreinforced, cement-bound concrete floors is presented. The work concentrates on cracking caused by shrinkage of the concrete used. The central components of ... [more ▼]

In the present study, a design concept for unreinforced, cement-bound concrete floors is presented. The work concentrates on cracking caused by shrinkage of the concrete used. The central components of the work are a numerical model (Finite element model) which, taking into account all time-dependent material parameters and with the aid of a simple calculation approach, is able to predict crack paths on sharp edges. In addition, with the help of the model, it is possible to simulate the curling of the corners of a float mounted concrete floor. For this purpose, the required material parameters (static elastic modulus, uniaxial tensile strength) were investigated under laboratory conditions and compared with prognosis values of an available prognosis software and with the analytical prognosis approach of DIN EN 1992-1-1: 2011-01. In a first step, the crack formation and crack development on a small, H-shaped concrete sample were examined and a crack path was calculated using a first numerical approach. This first numerical approach was subsequently validated on large-scale surfaces. On the basis of the large-scale experiments, the numerical model was further developed with regard to curling of concrete floors. All experiments were calculated with the approach of element failure method (EFM) using the commercial finite element software ANSYS. The design concept is completed by a parameter study. By means of this parameter study, it is possible to identify the parameters which decisively influences cracking. The present work thus makes an important contribution to the numerical modelling of damage in unreinforced concrete structures. [less ▲]

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See detailComputational Methods for Analysing Long-run Dynamics of Large Biological Networks
Yuan, Qixia UL

Doctoral thesis (2017)

Systems biology combines developments in the fields of computer science, mathematics, engineering, statistics, and biology to study biological networks from a holistic point of view in order to provide a ... [more ▼]

Systems biology combines developments in the fields of computer science, mathematics, engineering, statistics, and biology to study biological networks from a holistic point of view in order to provide a comprehensive, system level understanding of the underlying system. Recent developments in biological laboratory techniques have led to a slew of increasingly complex and large biological networks. This poses a challenge for formal representation and analysis of those large networks efficiently. To understand biology at the system level, the focus should be on understanding the structure and dynamics of cellular and organismal function, rather than on the characteristics of isolated parts of a cell or organism. One of the most important focuses is the long-run dynamics of a network, as they often correspond to the functional states, such as proliferation, apoptosis, and differentiation. In this thesis, we concentrate on how to analyse long-run dynamics of biological networks. In particular, we examine situations where the networks in question are very large. In the literature, quite a few mathematical models, such as ordinary differential equations, Petri nets, and Boolean networks (BNs), have been proposed for representing biological networks. These models provide different levels of details and have different advantages. Since we are interested in large networks and their long-run dynamics, we need to use ``coarse-grained" level models that focus on the system behaviour of the network while neglecting molecular details. In particular, we use probabilistic Boolean networks (PBNs) to describe biological networks. By focusing on the wiring of a network, a PBN not only simplifies the representation of the network, but it also captures the important characteristics of the dynamics of the network. Within the framework of PBNs, the analysis of long-run dynamics of a biological network can be performed with regard to two aspects. The first aspect lies in the identification of the so-called attractors of the constituent BNs of a PBN. An attractor of a BN is a set of states, inside which the network will stay forever once it goes in; thus capturing the network's long-term behaviour. A few methods have been discussed for computing attractors in the literature. For example, the binary decision diagram based approach and the satisfiability based approach. These methods, however, are either restricted by the network size, or can only be applied to synchronous networks where all the elements in the network are updated synchronously at each time step. To overcome these issues, we propose a decomposition-based method. The method works in three steps: we decompose a large network into small sub-networks, detect attractors in sub-networks, and recover the attractors of the original network using the attractors of the sub-networks. Our methods can be applied to both asynchronous networks, where only one element in the network is updated at each time step, and synchronous networks. Experimental results show that our proposed method is significantly faster than the state-of-the-art methods. The second aspect lies in the computation of steady-state probabilities of a PBN with perturbations. The perturbations of a PBN allow for a random, with a small probability, alteration of the current state of the PBN. In a PBN with perturbations, the long-run dynamics is characterised by the steady-state probability of being in a certain set of states. Various methods for computing steady-state probabilities can be applied to small networks. However, for large networks, the simulation-based statistical methods remain the only viable choice. A crucial issue for such methods is the efficiency. The long-run analysis of large networks requires the computation of steady-state probabilities to be finished as soon as possible. To reach this goal, we apply various techniques. First, we revive an efficient Monte Carlo simulation method called the two-state Markov chain approach for making the computations. We identify an initialisation problem, which may lead to biased results of this method, and propose several heuristics to avoid this problem. Secondly, we develop several techniques to speed up the simulation of PBNs. These techniques include the multiple central processing unit based parallelisation, the multiple graphic processing unit based parallelisation, and the structure-based parallelisation. Experimental results show that these techniques can lead to speedups from ten times to several hundreds of times. Lastly, we have implemented the above mentioned techniques for identification of attractors and the computation of steady-state probabilities in a tool called ASSA-PBN. A case-study for analysing an apoptosis network with this tool is provided. [less ▲]

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See detailEfficient and Secure Implementations of Lightweight Symmetric Cryptographic Primitives
Dinu, Dumitru Daniel UL

Doctoral thesis (2017)

This thesis is devoted to efficient and secure implementations of lightweight symmetric cryptographic primitives for resource-constrained devices such as wireless sensors and actuators that are typically ... [more ▼]

This thesis is devoted to efficient and secure implementations of lightweight symmetric cryptographic primitives for resource-constrained devices such as wireless sensors and actuators that are typically deployed in remote locations. In this setting, cryptographic algorithms must consume few computational resources and withstand a large variety of attacks, including side-channel attacks. The first part of this thesis is concerned with efficient software implementations of lightweight symmetric algorithms on 8, 16, and 32-bit microcontrollers. A first contribution of this part is the development of FELICS, an open-source benchmarking framework that facilitates the extraction of comparative performance figures from implementations of lightweight ciphers. Using FELICS, we conducted a fair evaluation of the implementation properties of 19 lightweight block ciphers in the context of two different usage scenarios, which are representatives for common security services in the Internet of Things (IoT). This study gives new insights into the link between the structure of a cryptographic algorithm and the performance it can achieve on embedded microcontrollers. Then, we present the SPARX family of lightweight ciphers and describe the impact of software efficiency in the process of shaping three instances of the family. Finally, we evaluate the cost of the main building blocks of symmetric algorithms to determine which are the most efficient ones. The contributions of this part are particularly valuable for designers of lightweight ciphers, software and security engineers, as well as standardization organizations. In the second part of this work, we focus on side-channel attacks that exploit the power consumption or the electromagnetic emanations of embedded devices executing unprotected implementations of lightweight algorithms. First, we evaluate different selection functions in the context of Correlation Power Analysis (CPA) to infer which operations are easy to attack. Second, we show that most implementations of the AES present in popular open-source cryptographic libraries are vulnerable to side-channel attacks such as CPA, even in a network protocol scenario where the attacker has limited control of the input. Moreover, we describe an optimal algorithm for recovery of the master key using CPA attacks. Third, we perform the first electromagnetic vulnerability analysis of Thread, a networking stack designed to facilitate secure communication between IoT devices. The third part of this thesis lies in the area of side-channel countermeasures against power and electromagnetic analysis attacks. We study efficient and secure expressions that compute simple bitwise functions on Boolean shares. To this end, we describe an algorithm for efficient search of expressions that have an optimal cost in number of elementary operations. Then, we introduce optimal expressions for first-order Boolean masking of bitwise AND and OR operations. Finally, we analyze the performance of three lightweight block ciphers protected using the optimal expressions. [less ▲]

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See detailProposal of a Failure Criterion of Adhesively Bonded Connections with Silicone
Staudt, Yves Nico Louis UL

Doctoral thesis (2017)

In the field of façade engineering, structural silicone sealants have been used in adhesively bonded connections since the 1960s. The low strength and stiffness of silicone rubber compared to other types ... [more ▼]

In the field of façade engineering, structural silicone sealants have been used in adhesively bonded connections since the 1960s. The low strength and stiffness of silicone rubber compared to other types of adhesives are compensated by the excellent adhesion properties and the good resistance against ageing and environmental influences, like UV radiation. Silicone sealants show a pronounced nonlinear material behaviour. The applicable design concepts in civil engineering propose simplified design equations, which are based on the assumption of a linear material law. Due to the current state of knowledge and to compensate the simplified model assumptions in the design concept, high reduction factors on the material strength and many restrictions on applications are defined. In order to overcome these drawbacks, the stress state within the sealant is increasingly described using the Finite Element Method. Considering the results of these analysis, the assessment of both the complex stress states with a suitable failure criterion and the influence of stress singularities on the failure behaviour constitute inevitable questions. The present work addresses these two questions. In the first step, the strain magnitude has been determined as a suitable failure criterion for the defect-free bulk material of the considered Dow Corning® 993 structural silicone sealant, subjected to a quasi-static loading. The failure criterion has been calibrated using the results of uniaxial tension as well as circular shear tests and validated with the results of compression tests. The strain magnitude is a strain-based failure criterion, which can be seen as a measure for the distortion of the molecular chains. In a second step, the stress distribution of the single-lap shear joint has been investigated in detail. For the assessment of the singular stresses and strains at the edge area of the interface between the adhesive and the substrate, referred to as two-material wedge, the so-called coupled stress and energy criterion, a concept of Finite Fracture Mechanics, was extended to nonlinear elastic material behaviour. Based on results of conduced simple shear tests on small bonded connections with varying adhesive thicknesses and overlap lengths, the coupled criterion was used to predict the crack initiation loads and a good agreement with the experimentally recorded values was obtained. Knowing the strength and the critical energy release rate of the material, the crack initiation load and the corresponding crack length are determined in the coupled criterion by solving an optimisation problem based on a Finite Element Analysis. The stress partial criterion has been modified to consider the strain magnitude as a failure criterion. In order to analyse the energy partial criterion, the critical energy release rate of Dow Corning® 993 structural silicone sealant has been determined in Double Cantilever Beam tests using the evaluation method based on the J-integral approach. Furthermore, concepts of the Theory of Critical Distances were used to determine the failure loads of the small scale tests. Unlike as for the notched circular shear tests and the tension tests on small scale bonded connections, good predictions were found in the Finite Element Analysis for the simple shear specimens, when a constant element size and formulation at the vicinity of the two-material wedge were used. Similar results were obtained with the point method and the control volume approach. These findings indicate that the characteristic material length for silicone rubber is not constant. [less ▲]

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See detailBig Data Architectures For Robust Systems
Falk, Eric UL

Doctoral thesis (2017)

Monitoring robustness of critical systems/infrastructures is the major use case for anomaly detection. A robust system designates a structure not only safe against intentional attacks, but also capable of ... [more ▼]

Monitoring robustness of critical systems/infrastructures is the major use case for anomaly detection. A robust system designates a structure not only safe against intentional attacks, but also capable of stemming internal failures. These systems face two primary risks: cyber attacks fall into the first category, whereas failing hardware components are part of the second category. In both cases, fast decision making is crucial. Hence, streaming data processing is the decisive asset to consider. With this background, in this thesis, we investigate two scenarios from the fields of mobile network sanity monitoring and cyber-physical security. Our contribution is threefold: We display how the real-time requirements of the two use cases push existing frameworks to their utter limits; We show which anomaly detection methods can be used to facilitate instant assessment rendering; We blueprint the extensions we contributed to big data frameworks, which are powering major silicon valley companies, to make them capable of supporting our use cases. The data-sets issued by our monitoring systems yield different properties than data from internet companies such as Google, Facebook or LinkedIn. In this work we establish our use cases, illustrate the mathematical models employed for the decision taking, and examine how big data architectures have to be altered to support our scenarios. [less ▲]

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See detailCONTRIBUTIONS TO THE STATISTICS OF RANDOM PROCESSES USING MALLIAVIN CALCULUS
Krein, Christian Yves Léopold UL

Doctoral thesis (2017)

In this dissertation we present several applications of Malliavin calculus, both to the statistical analysis of continuous time stochastic processes and to limit theorems for non-linear functionals of ... [more ▼]

In this dissertation we present several applications of Malliavin calculus, both to the statistical analysis of continuous time stochastic processes and to limit theorems for non-linear functionals of Gaussian Fields. Malliavin calculus extends techniques of classical calculus of variations from deterministic functions to random variables. In Malliavin calculus, the so called Malliavin derivative and its adjoint, the divergence operator, are combined with the theory of Hilbert spaces. Just as classical calculus, this theory has proved to be a powerful tool and its applications vary from the existence of densities, to the construction of estimators and the study of weak convergence of sequences of random variables and random vectors, with a special focus on normal approximations. The first part of the present document is essentially a generalization of a result of Privault and Réveillac (2008), which extends a seminal paper of Stein (1956). Stein has shown that, under certain conditions, there are biased estimators which perform better than the standard estimator for the mean of a multivariate normal vector. It has been shown by Privault and Réveillac that a similar statement holds for Gaussian processes and we shall present a generalization of their work to continuous time models, where the noise is either a chaotic Brownian martingale or a non-martingale noise living in the second Wiener chaos. This first part of the work corresponds to the paper "Drift estimation with non-gaussian noise using Malliavin Calculus" (2015) which has been published by the Electronic Journal of Statistics. In the second part of the work we give necessary and sufficient criteria for the convergence of sequences of random variables, living in a fixed sum of Wiener chaoses, to a limit which lives in the sum of the first two Wiener chaoses. Our results extend the important findings of Nualart and Peccati (2005), the so-called Fourth Moment Theorem, and a recent finding of Azmoodeh, Peccati and Poly (2014). Our criteria make use of the so-called Gamma-operators which are derived from scalar products of Malliavin derivatives and the infinitesimal generator of the Ornstein-Uhlenbeck semi-group, see for instance Azmoodeh, Peccati and Poly (2014). This part corresponds to the paper "Weak convergence on Wiener space: targeting the first two chaoses" (2017) which has been submitted to the Latin American Journal of Probability and Mathematical Statistics (ALEA). In the last part of the present work we consider a sequence living in a fixed Wiener chaos and converging in law to a normal variable. A second sequence is supposed to converge in law to a target variable which is the sum of a linear combination of independent chi-square distributed random variables and an independent normal variable. We derive conditions under which the sequence of random vectors, formed by both sequences of random variables, converges in law. We use again Gamma-operators and cumulants to derive necessary and sufficient conditions which can be seen as generalization of results of Peccati and Tudor (2005) for Gaussian limits in the case of sequences of random vectors which converge componentwise. We apply methods developed by Nourdin and Peccati (2009) to examine the rate of convergence of a sequence of double Wiener integrals towards a normal variable. [less ▲]

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See detailActive Harmonics Compensation in Smart Grids
Kobou Ngani, Patrick UL

Doctoral thesis (2017)

The quality of electric power is a key factor for the electricity supply service. It defines how good the characteristics of the supplied power meet the standard ones. Among several other power quality ... [more ▼]

The quality of electric power is a key factor for the electricity supply service. It defines how good the characteristics of the supplied power meet the standard ones. Among several other power quality issues, the harmonics are of more and more concern over the last decades. This is essentially due to the widespread use of electronic components. This thesis focuses on the development of a voltage active power filter implementing a new selective harmonics compensation algorithm. The first design is described as following: band-pass filters decompose the measured voltage signal as a sum of different harmonics voltages; PLLs (frequency-tuned) transform of the oscillating signals into two orthogonal and rotating components (dq-transform). The dq-components of each harmonic are controlled to zero using standard PI-controllers and the compensating harmonics waves are generated via the inverse PLL. All the harmonics compensating waves are superimposed and added to the fundamental reference signal. This represents the final control signal of the inverter. Implemented in the MATLAB-SIMULINK simulation environment, this foreseen methodology depicted as major issue the control stability especially when the system frequency differs from the rated 50-Hertz frequency. This is the reason why a second design has been proposed. The major improvement is done on the harmonics detection stability by replacing the PLLs frames by the well-known internal frame of the fundamental voltage of the controlled inverter. After the convincing theoretical results from the simulations, the method is implemented and validated experimentally on a test rig in the lab. The two key features of the developed active power filter (APF) are: 1)Its ability to be used as a standalone power unit that compensates by itself the harmonics that could appear in the system while generating the fundamental voltage necessary to build up the micro-grid. 2)Its ability to serve as a full grid-tied power element that not only mitigates the voltages harmonics on the coupled grid but also supports the grid by controlling the exchanged active and reactive powers between the inverter and the grid. In addition to the developed harmonic mitigation technique, a new grid synchronization method has been proposed along with a new power control algorithm combined with a grid impedance estimator for grid-tied inverter. Further investigations and development are required for three-phase unbalance voltage systems as well as for single-phase voltage power system for low power grids. [less ▲]

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See detailLearning Finite Automata via Flexible State-Merging and Applications in Networking
Hammerschmidt, Christian UL

Doctoral thesis (2017)

Being able to model behavior described by a linear sequence of observations (such as log files) goes a long way towards better understanding the underlying processes. This improved understanding can be ... [more ▼]

Being able to model behavior described by a linear sequence of observations (such as log files) goes a long way towards better understanding the underlying processes. This improved understanding can be very helpful in a number of activities, ranging from software (reverse) engineering to network traffic analysis. The developments in this thesis were driven by specific goals in predicting (human) behaviors captured by a software appliance observing network traffic and user requests to specific resources. Its final contributions have exceeded the original goals of the project in two important ways: I present (1) a flexible learning algorithm for finite automata accompanied by theoretical underpinning and its implementation, a contribution towards better learning algorithms, and (2) applications of the algorithm to use-cases in computer networking and beyond. The central algorithm considered in the thesis is a blue-fringe state-merging automaton learning algorithm, conducting a greedy search over feasible solutions. Its key components are a heuristic to search for consistent merges and an evaluation metric to assess the quality of a merge by assigning scores to merges. I generalize this framework by making the heuristic components explicitly parametric. While state-merging algorithms were originally defined for probabilistic and non-probabilistic finite state machines and later used to derive algorithms for more extended models such as real-time automata, the work presented here extends the scope of the algorithms to a wide range of ad-hoc defined models as well as enables the user to implement modifications to the heuristic search process. These modifications help to account for domain knowledge and richer semantics of models with a regular language core. I provide an implementation and a Python interface of the flexible state-merging framework, including stream/online and interactive variants of the algorithm based on a C++ implementation of the blue-fringe greedy search algorithm called DFASAT. The algorithm and the framework encompass and improve upon state-of-the-art approaches. The application problems considered in this thesis can be seen as classical classification and anomaly detection tasks in machine learning. The application domain is network traffic analysis with a focus on network security. I discuss the problematic properties of data from computer networks and address how using automaton models can help mitigate them. I then use the flexible state-merging approach for host profiling. I show how to efficiently learn finite state automata as behavioral profiles. These profiles can serve as digital fingerprints and help to identify malicious traffic such as botnet traffic. Moreover, I show how communication profiles can be used for sequence clustering on NetFlow data to distinguish different behaviors over time. [less ▲]

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See detailAPPROACHES FOR IDENTIFICATION OF TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL REGULATORS OF MESENCHYMAL STEM CELL DIFFERENTIATION USING TIME-SERIES EPIGENOMIC DATA
Gerard, Déborah UL

Doctoral thesis (2017)

Gene regulatory networks (GRNs) control cellular differentiation and development and recapitulate the physical interactions between transcription factors (TFs) and their influence on their target genes ... [more ▼]

Gene regulatory networks (GRNs) control cellular differentiation and development and recapitulate the physical interactions between transcription factors (TFs) and their influence on their target genes that ultimately results into a defined cell phenotype. In addition, cellular differentiation represents the path a cell undergoes through multiple stages before reaching a terminally differentiated state and is by nature dynamic. Moreover, epigenetic regulation as well as post-transcriptional control of gene expression are critical for faithful cellular phenotype. Cellular differentiation of progenitor cells into their daughter cells provide a dynamic controllable system to study the epigenetic mechanisms as well as the transcriptional output that take place towards cellular specifications, and the TFs and non-coding RNAs that dictate their differentiation. Here, we have generated time-series transcriptomic and epigenomic data during the differentiation of bone marrow stromal cells towards adipocytes and osteoblasts and characterized a novel approach called EPIC-DREM to construct dynamic GRNs of adipocytes and osteoblasts. In order to focus on shared transcriptional regulators of early commitment of bone marrow stromal cells towards adipocytes and osteoblasts, we have concentrated our analysis on dynamic super-enhancers to prioritize the identified TFs and discovered aryl hydrocarbon receptor (AHR) as a transcriptional regulator of the multipotent state. In addition, the generated of time-series epigenomic data were used as input for linear regression analysis that allowed to predict genes that are dynamically controlled by post-transcriptional regulators such as microRNAs (miRs). Indeed, genes that differ from their predicted expression level as assessed by the residuals of the linear regression model can be informative about their mRNA stability. In order to decipher genes that are under dynamic post-transcriptional control, the standard deviation of gene’s residuals was taken as a dynamic measure of changes in mRNA stability and clustering analysis coupled to microRNA motifs enrichment analysis allowed to identify post-transcriptionally co-regulated mRNAs. Based on the linear regressions analysis, miR-204 was identified as a potential regulator of adipogenesis. Integration of these types of data can contribute to the understanding of transcriptional and post-transcriptional control of cell differentiation and the here established approaches for key regulators identification can be widely applied to study other cell states transitions. [less ▲]

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See detailDeformation Based Curved Shape Representation
Demisse, Girum UL

Doctoral thesis (2017)

Representation and modelling of an objects' shape is critical in object recognition, synthesis, tracking and many other applications in computer vision. As a result, there is a wide range of approaches in ... [more ▼]

Representation and modelling of an objects' shape is critical in object recognition, synthesis, tracking and many other applications in computer vision. As a result, there is a wide range of approaches in formulating representation space and quantifying the notion of similarity between shapes. A similarity metric between shapes is a basic building block in modelling shape categories, optimizing shape valued functionals, and designing a classifier. Consequently, any subsequent shape based computation is fundamentally dependent on the computational efficiency, robustness, and invariance to shape preserving transformations of the defined similarity metric. In this thesis, we propose a novel finite dimensional shape representation framework that leads to a computationally efficient, closed form solution, and noise tolerant similarity distance function. Several important characteristics of the proposed curved shape representation approach are discussed in relation to earlier works. Subsequently, two different solutions are proposed for optimal parameter estimation of curved shapes. Hence, providing two possible solutions for the point correspondence estimation problem between two curved shapes. Later in the thesis, we show that several statistical models can readily be adapted to the proposed shape representation framework for object category modelling. The thesis finalizes by exploring potential applications of the proposed curved shape representation in 3D facial surface and facial expression representation and modelling. [less ▲]

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See detailWohnmobilität in der Großregion – eine interurbane Diskursanalyse mit Fokus auf den Städten Arlon, Thionville und Trier.
Christmann, Nathalie UL

Doctoral thesis (2017)

Effects of residential mobility moulding in uneven development in border regions can be perceived very differently by city councils or planners and the local population. This dissertation focuses on the ... [more ▼]

Effects of residential mobility moulding in uneven development in border regions can be perceived very differently by city councils or planners and the local population. This dissertation focuses on the perceptions of population mobility and dwelling in a transnational cross-border polycentric region in western Europe. The economic development of the Grand Duchy of Luxembourg calls for a constant expansion of the labour market, attracting cross-border commuters and highly mobile professional elites. The concomitant rises in property prices as well as the extreme housing shortages in Luxembourg have led to an expansion of the housing market into the border regions. So far studies have mostly dealt with the socio-demographic characteristics of the transmigrants. This research aims to detect people’s perceptions of the phenomenon by applying a discourse analysis, thus aiming to trigger an increasing awareness for the emerging transnational housing market. [less ▲]

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See detailArt as an Investment
Nasser Eddine, Ali UL

Doctoral thesis (2017)

During the 1970s and 1980s, the art markets gave abnormal returns. Individuals started speculating on art prices, and institutional investors soon entered the scene. Economists then began evaluating this ... [more ▼]

During the 1970s and 1980s, the art markets gave abnormal returns. Individuals started speculating on art prices, and institutional investors soon entered the scene. Economists then began evaluating this new alternative asset class. In this thesis, we review global art markets, analyze the methodologies employed for studying art as an investment, and seek answers to some fundamental questions. To build solid conclusions, we developed the largest up-to-date dataset of repeat sales of art objects. Our main additional contributions to the literature can be summarized as follows. First, we review and explain the growth in international art markets. Second, we show that it is unreasonable to make a comparison between the two main methodologies used for studying the investment perspective of art: the repeat-sales and hedonic regression frameworks. The returns estimated using the hedonic approach depend greatly on the specifications of the model. Thus, we find that of the two, the repeat-sales models are the most robust. Third, we study the returns on art after accounting for transaction costs. Importantly, we show that taking this fair view renders impractical the widely used art-investment measurement methodologies. Fourth, we revisit the “masterpiece effect”, and find strong evidence supporting its existence. Fifth, we investigate the potential of art investment. We find that the inclusion of art in an optimal portfolio depends significantly on the abnormal returns seen in the 1980s. Omitting these years leads to its exclusion. However, art may add a diversification benefit to an investment portfolio due to its low-to-negative correlation with other asset classes. Sixth, we analyze the optimal holding period of art and find that, in general, the returns increase with the length of the holding period. Nevertheless, we observe significant returns, accompanied with high levels of volatility, for trades made over very short time horizons. We notice that this “flipping” practice has been increasing in recent decades. Finally, we consider the effect some special cases have on art investment returns. We find that artworks that trade frequently tend not to outperform the market. Moreover, the nature of an artwork’s ownership history doesn’t alter returns. We also examine the returns on artworks selected by experts, and find that, surprisingly, they underperform. [less ▲]

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See detailA Model-Based Framework for Legal Policy Simulation and Compliance Checking
Soltana, Ghanem UL

Doctoral thesis (2017)

Information systems implementing requirements from laws and regulations, such as taxes and social benefits, need to be thoroughly verified to demonstrate their compliance. Several Verification and ... [more ▼]

Information systems implementing requirements from laws and regulations, such as taxes and social benefits, need to be thoroughly verified to demonstrate their compliance. Several Verification and Validation (V&V) techniques, such as reliability testing, and modeling and simulation, can be used for assessing that such systems meet their legal. Typically, one has to model the expected (legal) behavior of the system in a form that can be executed (simulated), subject the resulting models and the system to the same input data, and then compare the observed behavior of the model simulation and system execution. Existing V&V techniques often rely on code and complex logical expressions with no intuitive appeal to legal experts for specifying the expected behavior of a given system. Subsequently, one has no practical way to validate with legal experts that the underlying legal requirements are indeed complete and constitute a faithful representation of what needs to be implemented. Further, manually defining the expected behavior of a system and its test oracles is a tedious and error-prone task. The challenge here is to find a suitable knowledge representation that can be understood by all the involved stakeholders, e.g., software engineers and legal experts, but that remains complete and precise enough to enable automated analysis such as simulation and testing. As real data is seldom accessible in highly regulated domains, V&V requires the generation of synthetic testing data that can be used to build confidence in the reliability of the system under test. In particular, such data has to be structurally and logically well-formed to raise meaningful failures that can help reasoning about the reliability of the system under test. Further, the data should exhibit as much as possible the actual or anticipated system usage to help mimic how the system would behave under realistic circumstances. Generating such data is not a trivial task as the underlying data schemas are usually large and subject to numerous complex domain-related logical constraints. In this thesis, we investigate the use of the Unified Modeling Language (UML) and model-driven technologies, e.g., model to code transformations, to facilitate V&V activities for information systems that have to conform to laws and regulations, while tackling the above challenges. All our technical solutions have been developed and empirically evaluated in close collaboration with a government administration. Concretely, the technical solutions covered by this thesis include: - A modeling notation and methodology for formalizing legal policies. We propose a modeling notation and methodology for building abstract interpretations of the law. Models built using our methodology are simple enough to be understood by the involved stakeholders and are, at the same time, detailed enough to enable automated V&V activities. - A model-based simulation framework. We develop a model-based framework and associated tool support for simulating legal policies, when formalized using the aforementioned modeling methodology. Simulation provides a comparison baseline of how a compliant system should behave. Further, simulation is a mean to support decision-making when considering legal changes. Specifically, we report on a sizable case study where we assess the anticipated economic implications of a given policy change in Luxembourg’s tax law. - A model-based generator of test cases for reliability testing. We develop a heuristic approach for generating valid and representative test cases (data). Our generator is scalable and produces high-quality test data that is suitable for testing the reliability of data-intensive systems, e.g., a tax management system. [less ▲]

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See detailOn the Use of Alloy in Engineering Domain Specific Modeling Languages
Gammaitoni, Loïc UL

Doctoral thesis (2017)

Domain Specific Modeling Languages (DSMLs) tend to play a central role in modern design processes as they enable the effective involvement of domain experts by focusing on a particular problem domain ... [more ▼]

Domain Specific Modeling Languages (DSMLs) tend to play a central role in modern design processes as they enable the effective involvement of domain experts by focusing on a particular problem domain while abstracting away technical details. In this thesis, we investigate the specification of DSMLs with a particular focus on domain expert driven validation. Mainly, we are interested in developing Alloy-based approaches, allowing the definition of specifications from which instances can be generated and given to the domain experts for the sake of validation. The work we present in this thesis can be divided into three parts: The first part concerns the definition and execution of model transformations defined in Alloy. While Alloy analysis can be used as an execution engine for model transformations, the analysis process is time consuming. Model transformations playing a central role in DSML definitions, the development of a new model transformation language, named F-Alloy, retaining the benefits of Alloy with the added property of being efficiently computable was necessary. The second part focuses on validation. In that domain, our first contribution is a novel approach to the validation of model transformations called Visualization-Based Validation (VBV). VBV relies on the review by domain experts of intuitive depictions of model transformation traces to validate model transformation specifications. The whole process is made efficient by the usage of hybrid analysis, a combination of Alloy analysis and F-Alloy interpretation, allowing to reduce the time needed to analyze model transformations to the time needed to analyze its source. Our second contribution in the validation area is the definition of an Alloy-based approach to the specification and validation of DSMLs and of a design process defining how DSMLs can be validated using Alloy analysis at each iteration of the process. More precisely, we present how the abstract syntax, concrete syntax and operational semantics of a DSML can be defined using Alloy and F-Alloy, and show that the validation of a DSML' s abstract syntax and semantics benefits from the application of its concrete syntax. The third and last part aims at bringing those contributions to the practical world. To achieve this we developed a tool named Lightning implementing the aforementioned contributions. This tool, which belongs to the category of language workbenches, has been successfully used in an inter-disciplinary collaboration to define the Robot Perception System Language (RPSL). Based on this definition of RPSL, a framework has been developed to allow the execution of so called design space explorations. This framework represents a successful application of our approach to the real world problem of having RPSL specifications validated by experts in robotics. [less ▲]

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See detailLa compétence d'incrimination de l'Union européenne. Recherche sur le pouvoir pénal européen
Simon, Perrine UL

Doctoral thesis (2017)

The allocation by the Lisbon Treaty of a genuine criminalisation competence to the Union – article 83 TFEU – prompts the analysis of the existence and the exercice of European criminal law power. It ... [more ▼]

The allocation by the Lisbon Treaty of a genuine criminalisation competence to the Union – article 83 TFEU – prompts the analysis of the existence and the exercice of European criminal law power. It raises the question of the promotion, through criminalisation choices, of essential values to the community. Analysing the criminal law power is interconnected to the question about the nature of the European project as a whole, true existential space of society (ethos) or simple functional space comprised of objectives (telos). Despite the aspiration to clarify the delimitation of European penal power within the new treaty, its ambit remains unclear. An implicit criminalisation competence – an implied criminal law power – could still exist, allowing to overcome the minimum harmonisation provided for by article 83 TFEU. To admit such an implied power would mean revive competence creep. The exercice of the criminalisation competence is progressively framed, beyond the classical principles of subsidiarity and proportionality, by the criminal law principles of ultima ratio as well as the principles of legality and proportionality of criminal offences and penalties expressed in the Charter of fundamental rights. However, these principles have not been taken into account according to the actions of the legislator who appear to follow a securitarian trend. It is to the Court, through an in-depth proportionality check, to determine if the Charter can become the marker of criminal law policy characterised by its moderation and liberalism, and henceforth contribute to a European criminal law identity. [less ▲]

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See detailEnhancing Mobility Applications Through Bluetooth Communications
Bronzi, Walter UL

Doctoral thesis (2017)

In the world of short and medium-range wireless technologies, Bluetooth has recently come to the forefront of innovation. Within the next five years its market presence, especially in its Low Energy ... [more ▼]

In the world of short and medium-range wireless technologies, Bluetooth has recently come to the forefront of innovation. Within the next five years its market presence, especially in its Low Energy variation, is expected to nearly double across all market segments. The technology is quickly and steadily gaining importance for a wide range of applications with a specific focus on Internet of Things (IoT) devices. The growing availability and variety of such devices constitute an untapped potential that we plan on exploiting. Our focus in this thesis is to understand Bluetooth’s capabilities and explore its potential in mobile contexts. One specific field where this technology remains unexplored is Vehicular Ad Hoc Networks (VANETs). Because of the need to implement and moderate vehicular communications, the topic of Intelligent Transportation Systems (ITSs) is now trending more than ever. In this thesis we propose two ways we can benefit from Bluetooth in a mobile environment. Firstly, we consider the technology as a communication medium to investigate how di↵erent mobilities a↵ect the link performance between two devices. To do this, we define a set of communication experiments, in our case between two vehicles, to analyse how Bluetooth Low Energy (BLE) is a↵ected by varying speed, distance and traffic conditions. We find that the maximum communication range between two devices can go beyond 100m and that a robust connection, capable of handling sudden signal losses or interference, can be achieved up to a distance of 50m. The experiments were conducted using a proof-of-concept mobile application for o↵-the-shelf smartphones that can be used to transmit data over multiple hops in various Vehicle-to-Everything (V2X) scenarios. Secondly, we consider Bluetooth discovery capabilities as an information medium by using a connectionless approach to analyse di↵erent mobility frameworks. As there is an increasing need for vehicles and objects to become aware of their context, we implement Bluetooth as a sensing system to provide contextual information about its surroundings. Our challenge is to find out to what extent we can exploit the Bluetooth discovery and beaconing scheme for this purpose. We collect and analyse a dataset of Bluetooth Classic and BLE discoveries and evaluate their respective characteristics and ability to provide context-aware information from a vehicular perspective. By examining data recorded about encountered devices, such as quantity, quality of signal and device class information, we infer distinctive Bluetooth behaviours related to context and application. For this purpose, we propose a set a features to train a classification model to recognize di↵erent driving environments (i.e. road classes). Investigating the performance of our classifier, we were able to predict up to three classes (highway, city, extra-urban) by using only Bluetooth discovery data and no geographical information. This outcome gives promising results targeted at low energy and privacy-friendly applications and can open up a wide range of research directions. In conclusion, in this thesis we present two ways of applying Bluetooth to mobile contexts for deploying novel human mobility applications. [less ▲]

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See detailManaging the City-Region Like a Startup: Entrepreneurialism and Shifting Local Economic Governance in Developing Countries
Fegue, Jean Cyril UL

Doctoral thesis (2017)

The emerging experience of cities in the Global South regarding the complexity of their response to territorial competition's pressures requires the rethinking of the very concept of urban competitiveness ... [more ▼]

The emerging experience of cities in the Global South regarding the complexity of their response to territorial competition's pressures requires the rethinking of the very concept of urban competitiveness. This study proposes the distributionally-sensitive modeling of urban competitiveness (DS-MUC) in a perspective that is driven by the norm of Equity. The DS-MUC is posited as a critical theory to neoliberalism and as a contribution to the social sustainability and to the normative investigation of post-capitalist urban transformations in the Global South.The application of the DS-MUC in the investigation of Da Nang in Vietnam and Cebu City in the Philippines reveals that an interactive, relational and network-based entrepreneurial governance's capacity has a much greater proclivity to deliver Equity and therefore to achieve a 'high-quality competitiveness' than a city's organizing capacity embedded in illiberal, state-paternalistic and public-sector monopolistic arrangements. [less ▲]

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See detailCorporations and Human Rights: Searching for International Norms for Corporate Conduct in Domestic Case Law
Baglayan Ceyhan, Basak UL

Doctoral thesis (2017)

Recent years have seen much debate concerning the interplay between human rights and corporations. Part of that debate has focused on corporate violations of human rights norms and possible legal ... [more ▼]

Recent years have seen much debate concerning the interplay between human rights and corporations. Part of that debate has focused on corporate violations of human rights norms and possible legal accountability mechanisms for such breaches. The present research is concerned with one such accountability mechanism, namely litigation before domestic courts seeking to enforce corporations’ international obligations and the complaints before the OECD National Contact Points (‘NCPs’). The thesis analyses how domestic courts and the OECD NCPs have conceptualised and implemented corporations’ human rights obligations. It is premised on the assumption that, through their application of international norms in their particular national context, these institutions act to crystallize and clarify the ambit of such norms. [less ▲]

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See detailModel-Based Specification, Deployment and Adaptation of Robot Perception Systems
Hochgeschwender, Nico UL

Doctoral thesis (2017)

As robots are becoming ubiquitous and more capable, the need for introducing solid robot software development methods is pressing to increase robots' task spectrum. This thesis is concerned with improving ... [more ▼]

As robots are becoming ubiquitous and more capable, the need for introducing solid robot software development methods is pressing to increase robots' task spectrum. This thesis is concerned with improving software engineering of robot perception systems. The presented research employs a model-based approach to provide the means to represent knowledge about robotics software. The thesis is divided into three parts, namely research on the specification, deployment and adaptation of robot perception systems. The first part contributes the design and development of two domain-specific languages, namely RPSL and DepSL. Those languages provide suitable notations and abstractions to enable domain experts to express, compose and explore functional, architectural and deployment design decisions of robot perception systems. The resulting models are interpretable, thus they can be used not only to communicate design decisions to stakeholders, but also to verify them in an early development stage. The second part contributes means for deploying perception systems on real robot systems even in the presence of varying resource conditions. To this end, functional, architectural and deployment models are composed in a graph-structure. Such a graph enables not only humans, but also robots to derive implicitly defined information about their software both at design time and run time. The second part also contributes a reference architecture for deploying robot perception systems. The architecture provides a template solution for integrating not only the models required for deployment, but also all the other means required to carry out deployment. The third part utilizes both RPSL, DepSL and the reference architecture to specify, implement and evaluate three different robot perception systems. Those are capable to satisfy changing requirements induced, for example, by the robot's tasks or environment. This is achieved by proposing algorithms which derive adaptation actions based on models and varying requirements. [less ▲]

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See detailContextual Integrity and Tie Strength in Online Social Networks: Social Theory, User Study, Ontology, and Validation
Ahmed, Javed UL

Doctoral thesis (2017)

Online Social Networks (OSNs) have become an important part of daily digital interactions for more than half billion users around the world. Unconstrained by physical spaces, OSNs offer to social web ... [more ▼]

Online Social Networks (OSNs) have become an important part of daily digital interactions for more than half billion users around the world. Unconstrained by physical spaces, OSNs offer to social web users new means to communicate, interact, and socialize. Online social networks exhibit many of the characteristics of human societies in terms of forming relationships and sharing personal information. However, current OSNs mainly assume binary, static, and symmetric relationship of equal value between the connected users. In human societies, social relationships are of varying tie strength, dynamic, and asymmetric in nature. The lack of an effective mechanism to represent diversity in social relationships leads to undesirable consequences of users personal information leakage to the unwanted audience and raises privacy concerns. The issue of privacy has received significant attention in both the research literature and the mainstream media. In this dissertation, we conduct a user study to analyze users' attitude towards personal information disclosure in online social networks. The study gives insight into user's information sharing behavior and interaction patterns in online social networks. The findings reveal that personal information disclosure depends on the quality of relationship among the users and it can be easily inferred from user interaction pattern in online social networks. We propose a theoretical framework that addresses the aforementioned issue from a social science perspective and exploits existing social theories of Goffman, Granovetter, and Nissenbaum to model social privacy for OSNs users. Based on this theoretical framework, we developed SOCPRI (SOCial PRIvacy) ontology to represent diversity in social relationships in online social networks. This model regulates personal information disclosure on the basis of the social role and the relationship quality between the OSNs users. The model is evaluated by translating competency questions into description logic (DL) queries to demonstrate the applicability of our approach. The results of ontology evaluation demonstrate the appropriateness of our ontology against proposed requirements. Based on this model a privacy-friendly online social networking environment can be developed to address some of the existing issues such as context collapse and user control. [less ▲]

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See detailForm und Funktion des Diminutivs im luxemburgisch-moselfränkischen Übergangsgebiet
Edelhoff, Maike UL

Doctoral thesis (2017)

Diminutive formation is a common word formation process of the Luxembourgish (Lux.) lan-guage and the neighbouring Moselle-Franconian (MsFrc) dialects. The aim of this thesis is to collect and to analyse ... [more ▼]

Diminutive formation is a common word formation process of the Luxembourgish (Lux.) lan-guage and the neighbouring Moselle-Franconian (MsFrc) dialects. The aim of this thesis is to collect and to analyse the characteristics of this process, integrate them into common morpho-logical theories and to establish their geolinguistic properties. On a functional level, the diminutives show the same characteristics in both varieties although the loss of the evaluative meaning is further developed in Lux. than in MsFrc. How-ever, the most apparent differences can be seen on the level of the fomal execution of the di-minutive rule: While the diminutives in MsFrc share many similarities, such as grammatical gender, the singular suffix and to an extent also the plural marking with Standard German, the Lux. language differs greatly from the others. In Lux. the singular formation is quite similar to the one in the other varieties, however, the plural suffix is triggered by the syllabic and prosodic properties of the base noun. Additionally, the grammatical gender of the diminutive is in con-cordance with the gender of the base noun and hence, not influenced by the suffix. The reasons for these peculiar attributes are to be found both in the historical development of the language and its current structural form as well as in its sociolinguistic context. The consequences of the differing structural properties are clearly displayed on a geo-linguistic level. Although the varieties are historically closely related the differing formal ex-pressions of the diminutive meaning lead to the emergence of groups of isoglosses coinciding with the state border. In brief, the history and the present situation of the diminutive serve as evidence that the dialect continuum that once crossed the state border has been falling apart and that it has been replaced by a solid linguistic border that separates the closely related varieties from each other. [less ▲]

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See detailIndividual rights under Union law. A study on the relation between rights, obligations and interests in the case law of the Court of Justice
Warin, Catherine Anne Sophie UL

Doctoral thesis (2017)

In the increasingly rights-centred legal system of the Union, the concept of individual rights is the source of growing confusion, and is more than ever in need of clarification. This thesis addresses the ... [more ▼]

In the increasingly rights-centred legal system of the Union, the concept of individual rights is the source of growing confusion, and is more than ever in need of clarification. This thesis addresses the following questions. Firstly, how does the relation between rights, obligations and interests define the nature and function of individual rights in the Union’s legal order? Secondly, to what extent is the evolution of the Union’s constitutional framework challenging the original concept of individual rights? These questions are addressed essentially by tracing the development of the CJEU’s method for identifying individual rights and by mapping the relation between rights, obligations and interests that emerges from the case law. The basic characteristics of the concept of individual rights are inferred from this relation. The case law on individual rights is examined through the lens of the basic concept of individual rights, i.e. in the light of the relation between rights, obligations and interests. The study scrutinises cases in which this relation took shape and is still developing, looking in turn at the protection of economic, non-economic, and collective interests. Special attention is paid to the impact of the introduction of the Charter of Fundamental Rights in the EU legal order as well as to the implications of the EU concept of rights for the requirement of an effective remedy. [less ▲]

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See detailLe mouvement-liberté. Généalogie philosophique et littéraire d'un imaginaire politique
Jeusette, Julien UL

Doctoral thesis (2017)

Cette thèse, qui se situe au croisement de trois champs de recherche (la littérature, la philosophie, l’histoire des idées), a pour ambition de retracer la manière dont le déracinement, le nomadisme et ... [more ▼]

Cette thèse, qui se situe au croisement de trois champs de recherche (la littérature, la philosophie, l’histoire des idées), a pour ambition de retracer la manière dont le déracinement, le nomadisme et l’errance ont été investis, à un moment donné de notre Histoire, d’une appréciation positive, au moment même où la sédentarité et l’enracinement se sont vus taxés de conservatisme ennuyeux. Nous postulons que cet imaginaire politique, que nous appelons « mouvement-liberté » (tout discours axiologique valorisant le mouvement libre et infini, et dévalorisant toute forme d’immobilité), émerge dans Les Nourritures terrestres d’André Gide et dans Ainsi parlait Zarathoustra de Nietzsche à la fin du XIXe siècle. Nous montrons ensuite que ce discours s’amplifie au cours des années 1920-1930, notamment au sein des textes que nous avons qualifiés de « romans de fuite » ; la troisième partie de la thèse porte sur les années 1960-1970 et met en évidence la redondance discursive du « mouvement-liberté » au sein de la « French theory ». La dernière partie met en lumière la façon dont le « mouvement-liberté », qui était politiquement critique et explicitement de l’ordre du contre-pouvoir de la fin du XIXe siècle jusqu’aux années 1970, est aujourd’hui récupéré par le néolibéralisme, qui le revendique pour son propre compte et le travestit en « idéologie nomade ». [less ▲]

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See detailIn Luxemburg mit Portugal verbunden : Eine Verflechtungsgeschichte portugiesischer Migrantenvereine in Luxemburg und Portugals Emigrationspolitik (1974-1997).
Hinger, Thierry Pierre UL

Doctoral thesis (2017)

The thesis is a contribution to the migration history of Luxembourg and Portugal for the period between 1974 and the end of the 20th century. It analyses the entangled history of the Portuguese migrant ... [more ▼]

The thesis is a contribution to the migration history of Luxembourg and Portugal for the period between 1974 and the end of the 20th century. It analyses the entangled history of the Portuguese migrant organizations in Luxembourg and the emigration policy of Portugal in the context of the Portuguese nation (re-)building process that took place after the end of dictatorship and the loss of the empire, in Portugal and abroad. No more an imperial nation, Portugal became after April 25 1974 what Dufoix calls a trans-territorial nation. It emphasized the role of the Portuguese living abroad as a part of the nation and adopted an emigration policy that aimed at protecting the Portuguese migrants and strengthening their ties with Portugal. The entanglement of the two actors, the migrant organizations and the Portuguese state, in Luxembourg reveals their interrelation in the fields of political participation across borders, economics, and culture and education. They offered the Portuguese migrants in Luxembourg ways and means to maintain cross-border connections with Portugal, and must therefore be considered as two actors in the Portuguese nation (re-)building process that took place in Luxembourg. The thesis offers a historical account of the institutional role of the state of origin with its emigration policy and the migrant’s organizations in the country of destination in maintaining cross-border connections with the country of origin. [less ▲]

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See detailAb initio approaches to Resonant Raman Spectroscopy of Transition Metal Dichalcogenides
Pereira Coutada Miranda, Henrique UL

Doctoral thesis (2017)

This thesis deals with the theory and simulation of resonant Raman spectroscopy in two-dimensional transition metal dichalcogenides. We present two different ab initio approaches. In the first, we ... [more ▼]

This thesis deals with the theory and simulation of resonant Raman spectroscopy in two-dimensional transition metal dichalcogenides. We present two different ab initio approaches. In the first, we calculate the Raman susceptibility tensor as a function of laser energy from the change of the dielectric susceptibility with atomic displacements. In the second, we formulate the Raman tensor in terms of time-dependent perturbation theory and calculate it using electron-light and electron-phonon coupling matrix elements obtained from density functional theory. We investigate the role of resonance, quantum interference and excitonic effects in the Raman spectra of single and triple-layer MoTe2. We compare our simulations with experimental results, explaining the dependence of the Raman intensities on the excitation energy. We demonstrate that the two approaches are formally and numerically equivalent in the adiabatic limit. In addition, the second approach allows to include the dynamical effects and captures a shift of the intensities with respect to the adiabatic case. This method is also more computationally efficient and is extended to include temperature effects using many-body perturbation theory. We have implemented both of these methods in a software package with interfaces to open source ab initio codes. Furthermore, we have developed web based tools to visualize excitonic states and phonon modes. [less ▲]

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See detailTESTING 21ST CENTURY SKILLS IN A CHANGING NATURE OF WORK: THE CONSTRUCT VALIDITY OF COMPLEX PROBLEM SOLVING AND ORGANIZATIONAL LEARNING
Mainert, Jakob Simon UL

Doctoral thesis (2017)

This thesis investigates the empirical assessment and construct validity of complex problem-solving (CPS) skills and organizational learning (OL) in a changing nature of work. Technological and ... [more ▼]

This thesis investigates the empirical assessment and construct validity of complex problem-solving (CPS) skills and organizational learning (OL) in a changing nature of work. Technological and organizational change enlarge the gap between the type of employee required by the market and the employees who are actually being provided by higher education as human capital to the market. Two constructs, CPS and OL, might strengthen human capital to close the emerging gap in a changing nature of work. [less ▲]

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See detailL'intégration des élèves nouvellement arrivés en France dans l'espace scolaire français. Langues, représentations, identités en contexte.
Kadas, Timea UL

Doctoral thesis (2017)

Our thesis focuses on newcomer students in France and aims at understanding how these students integrate into French schools and exploring the educational paths they tread. Thus, this study is based ... [more ▼]

Our thesis focuses on newcomer students in France and aims at understanding how these students integrate into French schools and exploring the educational paths they tread. Thus, this study is based mainly on the analysis of the discourse of thirteen students concerning their learning and their school experiences. It is also based on the representations that these students have of themselves, others (French students, teachers), their learning in general, their learning of the French language in particular and the context in which this learning takes place. Our thesis also focuses on the students’ first languages and their role in the learning process. The link between language and identity has long been established by researchers from different disciplines. Therefore, we have tried to understand, through an autobiographical project based on the notions of multiliteracy and multimodality, how the first languages of the students can be taken into consideration in order to help them progress in both the learning of French and learning in general. We also considered the significance of such an approach in the reconstruction of these students' identities. Furthermore, in response to our initial question regarding how these students integrate into the French education system, we investigated two complementary perspectives: that of the institution through interviews with three teachers, three heads of school and two inspectors and that of the students’ families through questioning nine parents. The aim of this study is to contribute to the body of research on the role of migration in the French educational context and to provide a better understanding of the current educational challenges facing our globalized society. [less ▲]

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See detailStem cells for modeling Parkinson's disease
Nickels, Sarah Louise UL

Doctoral thesis (2017)

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See detailANALYSIS OF NEURONAL DIFFERENTIATION IN GENETIC FORMS OF PARKINSON’S DISEASE REVEALS A NEURODEVELOPMENTAL CONTRIBUTION
Walter, Jonas UL

Doctoral thesis (2017)

During the mammalian embryonic neurodevelopment, all neurons descend from neuroepithelial stem cells. Accumulating evidences indicate a contribution of neurodevelopmental processes to the vulnerability to ... [more ▼]

During the mammalian embryonic neurodevelopment, all neurons descend from neuroepithelial stem cells. Accumulating evidences indicate a contribution of neurodevelopmental processes to the vulnerability to diseases. Here, we elucidate such developmental contribution in the context of Parkinson’s disease by combining high content imaging approaches, single-cell RNA sequencing, 3D image analysis, and multifactorial functional mitochondrial readouts. We found that the prominent PD-associated LRRK2-G2019S mutation accelerates dopaminergic neuron differentiation, accompanied by a reduced viability, resulting in indistinguishable dopaminergic neuron quantities. Our data indicate that the unexpected dynamics is driven by LRRK2-G2019S-dependent aberrations in gene expression as well as mitochondrial health and biogenesis of the neuroepithelial stem cell population. We conclude that LRRK2-G2019S modifies the dynamics of dopaminergic neuron fate specification during development, what may constitute a predisposition to parts of the PD-associated clinical manifestations. [less ▲]

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See detailHistoricizing the journey of the New Math reform from the United States to Luxembourg in the 1960s and 1970s
Nadimi Amiri, Shaghayegh UL

Doctoral thesis (2017)

This research investigates the process of the New Math, an internationally disseminated reform of school mathematics in the Grand Duchy of Luxembourg, during the 1960s and 1970s. This mathematics reform ... [more ▼]

This research investigates the process of the New Math, an internationally disseminated reform of school mathematics in the Grand Duchy of Luxembourg, during the 1960s and 1970s. This mathematics reform was propagated in the Western side of the Cold War to promote the mathematical and scientific power of Western countries. With this initial objective as a core of the study, the research then expands the area of the research to look at the mathematics education in the western countries. Timewise also, this expansion goes beyond the 1960s and 1970s, the era of the New Math reform. Thus, in a broader perspective, the research attempts to study what school policymakers expect from school mathematics historically in Western countries. It studies how the background idea and reasoning of the New Math reform through the journey of the reform from the United States to Europe and Luxembourg was changed and adapted to be applicable in the educational context of Luxembourg. The three main questions of the research are: 1 How was the New Math reform received and advanced in Luxembourg? 2 What did Luxembourgers expect from their school mathematics? Or Why students in Luxembourg should learn mathematics? 3 What was the reasoning behind mathematics education in Western countries through the history of schooling? The research began by exploratory methods to clear the property of the research and to determine the data collection method and other features that research needed to improve its design. This approach led to a collection of data including documents related to the context of Luxembourg, and context outside Luxembourg. This collection included both primary and secondary sources. The research studied texts of laws, regulations, newspapers, conference proceedings of the era, mathematics textbooks, teacher journals and other officially published sources as well as unpublished sources such as correspondences between different actors related to the school system and math education. For reading and analyzing data, the research was inspired by Foucault’s archeological approach in historical research and the study of different layers, which shape the discourse. In addition to Foucault, Popkewitz (e.g., 1997, 2009; Popkewitz & Lindblad, 2004) and Hacking (2012) inspired the work in developing the historical study of the reasoning. The research indicated two paradigms, which shaped the answers to the questions “why students should learn mathematics.” The first paradigm supports the reasoning, which argues that mathematics education should improve thinking ability, mental power and intellectuality. The research showed that these two paradigms shaped the discourse before and during the New Math reform and in different contexts and culture. [less ▲]

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See detailInflammatory signaling in liver cells: Cross-regulation of the IL-6/JAK/STAT3 pathway and microRNAs
Servais, Florence UL

Doctoral thesis (2017)

Interleukin-6 (IL-6) plays important roles in the regulation of liver functions and promotes the development of hepatocellular carcinoma (HCC), the most common primary liver cancer. Whereas protein ... [more ▼]

Interleukin-6 (IL-6) plays important roles in the regulation of liver functions and promotes the development of hepatocellular carcinoma (HCC), the most common primary liver cancer. Whereas protein-encoding genes are well-studied, the contribution of IL-6-regulated microRNAs (miRNAs) to its effects is largely unexplored. Similarly, little is known about miRNAs regulating key molecules of the IL-6/JAK/STAT3 signaling pathway. In the main part of this thesis, cell-based high-throughput screenings systems were developed, allowing the identification of miRNAs interfering with the IL-6/JAK/STAT3 signaling. Out of 538 miRNA mimics, this dual screening approach followed by various validation steps (luciferase-3’UTR-reporter assays, western blot and flow cytometry analyses) allowed us to identify twelve miRNAs targeting STAT3, JAK1, SOCS3, IL6R and/or gp130, ten of them had not yet been reported as regulators of this pathway before. In the second part of this work, microarray analyses revealed that primary hepatocytes are considerably more responsive to IL-6 stimulation regarding changes in their miRNomes than liver-derived cell lines. Despite their weaker response, one of the top regulated miRNA found in the primary hepatocytes, miR-146b-5p, could also be induced by IL-6-type cytokines (IL-6 and Oncostatin M) in cell lines. Its functional role(s) in hepatocytes are currently investigated. A larger, comparative study included additionally Interferon gamma and IL-27, cytokines with a STAT1-dominated response, and supplementary cell lines originating not only from the liver but also from other tissues. While all cytokines had profound effects on the mRNA transcriptomes, only very small to moderate changes were observed at the miRNome level, suggesting that the regulation mediated by cytokines mainly happens through the modulation of protein-coding genes rather than by fine-tuning via miRNAs. Additionally, we analyzed expression of a broad panel of cytokines in sera of 125 patients with liver diseases (steatosis, non-alcoholic steatohepatitis, HCC) by bead-based multiplex immunoassays. We observed that, for example, serum HGF, IL-6 and IL-8 levels increased in relation with the severeness of liver pathology while PDGF-BB and RANTES decreased. When investigating the impact of the patatin-like phospholipase domain-containing protein 3 variant I148M (PNPLA3 I148M), known to be a risk factor for the development of liver diseases, on the serum levels of cytokines, no significant differences could be observed between the different genotypes. In this PhD thesis, we identified and characterized miRNAs relevant for the IL-6/JAK/STAT3 signaling pathway, including miR-146b-5p as an IL-6-inducible miRNA. Others like miR-194-5p, miR-4473 and miR-548k were demonstrated to be negative regulators of this pathway and may be of potential therapeutic significance. In addition, we showed that, while miRNAs can modulate this pathway, IL-6 seems to rather regulate the mRNA transcriptome than the miRNome. [less ▲]

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See detailKusuoka-Stroock type bounds for densities related to low-dimensional projections of high-dimensional SDE
Ledent, Antoine Patrick Isabelle Eric UL

Doctoral thesis (2017)

One of the purposes of this thesis is to use Malliavin calculus and Stochastic Taylor expansions to study the densities of interacting systems of stochastic differential equations (SDE), seen as ... [more ▼]

One of the purposes of this thesis is to use Malliavin calculus and Stochastic Taylor expansions to study the densities of interacting systems of stochastic differential equations (SDE), seen as projections of SDE onto a low-dimensional space, and to control the dependence of the constants on the dimension of the background space. The setting includes time-dependent SDE and a relatively large class of path-dependent SDE. Several results also shed light on the classical theory of SDE, independently of the control on the constants. In Part 1, assuming the system satisfies suitably defined projected equivalents of the classic ellipticity or weak Hörmander conditions, we prove Gaussian estimates in terms of the Euclidean distance where, provided natural assumptions, for a fixed target-space dimension, the constants depend polynomially on the background dimension, and, in the elliptic case, on the number of driving Brownian motions. In Part 2, we first define suitable generalisations of (time-dependent) control distances and prove Kusuoka-Stroock type results without control on the constants. In particular, we obtain a time-dependent extension of a result of Léandre about SDE with non-trivial drifts, i.e., drifts which are not uniformly contained in the span of the other vector fields. Then, we introduce a condition which we call the `Progressive Hörmander condition' and prove similar control-type estimates valid under this assumption, with polynomial control on the growth of the constants with background space dimension. The condition is of independent interest in the study of SDE, and shows the connection between the classic works of Ben Arous, Kusuoka, Léandre and Stroock, and the more recent works of Bally, Caramellino, Delarue, Menozzi and Pigato. To main technique required is the study of density and scaling properties of some careful choice of linear combinations of terms of the signature of the driving path. In Part 3, we introduce a stricter condition called the `separated progressive Hörmander condition', and prove lower bounds and local strict positivity under this assumption. (By `local' we mean local around the solution of the deterministic ODE driven by a null control, rather than local round the initial point.) The main technical difficulty is the identification of points contained in the interior of the support of the log-signature of the path in the d dimensional Euclidean space composed of d Brownian motions and a deterministic linear component. The purpose of Part 4 is to use some results and techniques of the rest of the thesis to prove extensions of a theorem of Löcherbach about uniformly elliptic interacting branching diffusions. [less ▲]

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See detailMolecular mechanisms of kinase inhibitor resistance in melanoma
Cesi, Giulia UL

Doctoral thesis (2017)

In my thesis, I elucidated several aspects of melanoma biology, all related to the influence of targeted therapies in both responding and resistant melanoma cells. To better understand the MAPK signalling ... [more ▼]

In my thesis, I elucidated several aspects of melanoma biology, all related to the influence of targeted therapies in both responding and resistant melanoma cells. To better understand the MAPK signalling pathway, the impact of BRAF inhibitors on metabolic alterations as well as the connection between BRAF inhibitors and the onset of drug resistance was investigated. This introduction is focused on four topics: i) melanoma, ii) cancer metabolism, iii) miRNAs and iv) extracellular vesicles. First, melanoma biology including incidence rates, etiology, canonical and altered signalling pathways, therapies and resistance mechanisms will be introduced. The second part of the introduction will concentrate on metabolic alterations in the context of cancer and their implication on proliferation and survival. Thirdly, miRNAs and extracellular vesicles will be illustrated providing insights into their role in cancer development and especially drug resistance [less ▲]

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See detailCHARACTERIZATION OF PARKINSON’S DISEASE GENE DJ-1/PARK7 IN CD4+CD25+FOXP3+ REGULATORY T-CELLS
Danileviciute, Egle UL

Doctoral thesis (2017)

DJ-1, also known as PARK7, as its name suggests, is one of the familial Parkinson’s disease (PD) genes. Defects in human DJ-1 are the cause of autosomal recessive early-onset PD. DJ-1 is a redox ... [more ▼]

DJ-1, also known as PARK7, as its name suggests, is one of the familial Parkinson’s disease (PD) genes. Defects in human DJ-1 are the cause of autosomal recessive early-onset PD. DJ-1 is a redox-responsive protein and is long thought to mainly play an essential protective role in neurons. DJ-1 is ubiquitously expressed throughout the body rather than only in brain and is involved in several biological functions. We here seek to characterize a novel role of DJ-1 in regulatory T cells, currently recognized as CD4+CD25+FOXP3+ regulatory T-cells (Tregs), which are well-known immune suppressor cells in many peripheral diseases and emerging to play a role in several neurodegenerative diseases. [less ▲]

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See detailEssays on Asset Pricing Models with Jump Processes
Cui, Xuecan UL

Doctoral thesis (2017)

This dissertation contains four autonomous academic papers on asset pricing models with jump processes, including the studies of equilibrium asset pricing model, option pricing model, and empirical test ... [more ▼]

This dissertation contains four autonomous academic papers on asset pricing models with jump processes, including the studies of equilibrium asset pricing model, option pricing model, and empirical test. The common thread between them is the application of jump processes that links them in asset price modeling. The first three papers study Lévy process and its inhomogeneous extensions, while the last one studies contagious Hawkes processes. The first essay proposes a novel equilibrium asset pricing model under the semiparametric jump diffusion framework, including drift, volatility and jump intensity in a general time-varying form. The corresponding pricing kernel provides insights on option pricing, and equity premium puzzle [Mehra & Prescott (1985)]. The analytical solutions of equity premium and European call option are given as well. The second essay introduces a new econometric method/procedure to disentangle the three time-varying components of drift, volatility and jump in asset prices. By combining Hodrick-Prescott filter and particle filters, I decomposed the three timevarying components in the S&P500 index, and observed the clustering of volatility and jumps, though the clustering effects are more pronounced when the time-varying drift is negative. Empirical results support the proposed time-varying jump diffusion asset pricing model in Chapter 2. The third essay studies the (un)importance of small jumps in option pricing models. The option pricing literature argues that the behavior of small jumps in a Geometric Lévy model is of paramount importance [Carr et al. (2002)]. This is evidently true for very short time horizons and very deep in- and out-of-the-money options. In this paper, we took the complementary view and asked what values of time to maturity and option moneyness in a Geometric Lévy model lead to option prices, which are practically indistinguishable from the price of plain vanilla options in the BlackScholes model. In other words, in what situation that the Lévy model in question can be replaced with a Brownian motion with minimal pricing error. We produced explicit tight bounds in the case of a Poisson jump process, and related heuristic bounds for arbitrary Lévy process with exponentially decaying jump intensity. The fourth essay models and tests contagious jumps in bull/bear market regimes, in which I developed the regime switching Hawkes processes to model the contagious asset jumps in the international stock market. This new model allows serial and regional contagion in international asset prices, in which contagious impact can be flexible to accommodate different market conditions. [less ▲]

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See detailAutomated and Effective Security Testing for XML-based Vulnerabilities
Jan, Sadeeq UL

Doctoral thesis (2017)

Nowadays, the External Markup Language (XML) is the most commonly used technology in web services for enabling service providers and consumers to exchange data. XML is also widely used to store data and ... [more ▼]

Nowadays, the External Markup Language (XML) is the most commonly used technology in web services for enabling service providers and consumers to exchange data. XML is also widely used to store data and configuration files that control the operation of software systems. Nevertheless, XML suffers from several well-known vulnerabilities such as XML Injections (XMLi). Any exploitation of these vulnerabilities might cause serious and undesirable consequences, e.g., denial of service and accessing or modifying highly-confidential data. Fuzz testing techniques have been investigated in the literature to detect XMLi vulnerabilities. However, their success rate tends to be very low since they cannot generate complex test inputs required for the detection of these vulnerabilities. Furthermore, these approaches are not effective for real-world complex XML-based enterprise systems, which are composed of several components including front-end web applications, XML gateway/firewall, and back-end web services. In this dissertation, we propose several automated security testing strategies for detecting XML-based vulnerabilities. In particular, we tackle the challenges of security testing in an industrial context. Our proposed strategies, target various and complementary aspects of security testing for XML-based systems, e.g., test case generation for XML gateway/firewall. The development and evaluation of these strategies have been done in close collaboration with a leading financial service provider in Luxembourg/Switzerland, namely SIX Payment Services (formerly known as CETREL S.A.). SIX Payment Services processes several thousand financial transactions daily, providing a range of financial services, e.g., online payments, issuing of credit and debit cards. The main research contributions of this dissertation are: -A large-scale and systematic experimental assessment for detecting vulnerabilities in numerous widely-used XML parsers and the underlying systems using them. In particular, we targeted two common XML parser’s vulnerabilities: (i) XML Billion Laughs (BIL), and (ii) XML External Entities (XXE). - A novel automated testing approach, that is based on constraint-solving and input mutation techniques, to detect XMLi vulnerabilities in XML gateway/firewall and back-end web services. - A black-box search-based testing approach to detect XMLi vulnerabilities in front-end web applications. Genetic algorithms are used to search for inputs that can manipulate the application to generate malicious XML messages. - An in-depth analysis of various search algorithms and fitness functions, to improve the search-based testing approach for front-end web applications. - Extensive evaluations of our proposed testing strategies on numerous real-world industrial web services, XML gateway/firewall, and web applications as well as several open-source systems. [less ▲]

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See detailACTIVITY-TRAVEL BEHAVIOUR IN THE CONTEXT OF WORKPLACE RELOCATION
Sprumont, François UL

Doctoral thesis (2017)

Travel behaviour analysis is a complex task because of the myriad of determinants influencing decision makers. The commuting trip constitutes an important travel purpose, but is not the dominant one ... [more ▼]

Travel behaviour analysis is a complex task because of the myriad of determinants influencing decision makers. The commuting trip constitutes an important travel purpose, but is not the dominant one. Because of its spatial and temporal concentration, the commuting flow is an ideal target for mobility management measures aiming at decreasing its negative externalities. Nevertheless, commuting travels are done in the frame of a more complex activity-travel chain, and some choices, whether on the short term (e.g. commuting mode choice) or in the longer term (e.g. where to live, buy a car) are done considering an ensemble of trips. Our research hypothesis is that workplace relocation, or more generally an event that strongly affects travellers’ trip chains, induces different and interrelated responses. Our research aim is to gain insight into this complex decision-making process, in order to better understand its relation with transport policy measures. [less ▲]

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See detailCRISPR/CAS9 AND PIGGYBAC MEDIATED LRRK2-G2019S IN VITRO PARKINSON’S DISEASE MODELING
Qing, Xiaobing UL

Doctoral thesis (2017)

Parkinson’s disease (PD), the second most common neurodegenerative disorder, is characterized by the progressive loss of dopaminergic (DA) neurons in the substantial nigra pars compacta (SNpc) area of the ... [more ▼]

Parkinson’s disease (PD), the second most common neurodegenerative disorder, is characterized by the progressive loss of dopaminergic (DA) neurons in the substantial nigra pars compacta (SNpc) area of the human midbrain with an unclear cause. Mutations revealed by whole genome sequencing (WGS) from familial PD cases may explain how cell loss occurs. Confirmation of this hypothesis has been hampered by the lack of available cell types from affected patients. Transgenic animal models have been used, but differences between these animals and humans have greatly impacted their usefulness for studying human diseases. Additionally, because PD is regarded to only affect humans, reliable human material-based experimental models are urgently needed. Human-induced pluripotent stem cells (hiPSCs)- derived DA neurons provide an opportunity to establish in vitro mutation-related PD models of disease-relevant cells that represent replacement alternatives to in vivo animal experiments. However, these hiPSCs-based PD models have limitations regarding the genetic background differences between patients and healthy controls. Genomic editing of hiPSCs allows for the generation of isogenic cellular models that differ only in the disease-specific mutations of interest. Currently, the biggest concern regarding nuclease-mediated genomic editing is the potentially undesirable alterations associated with remnant sequences, off-target effects and random integration, which may result in cell lines not being truly isogenic. To avoid potential confounding effects and establish a causal link between genotype and phenotype, robust isogenic cell lines free of unwanted mutagenesis are absolutely required for the study of PD. To better understand the pathogenesis of the most prevalent leucine-rich repeat kinase 2 (LRRK2) mutation, G2019S, which causes both familial and sporadic PD, patient hiPSCs have been corrected using the Cre/LoxP recombination system. However, the LoxP site inevitably remaining after excision of the selection cassette can influence gene expression. In this thesis, a “footprint-free” LRRK2-G2019S isogenic model was created using clustered regularly interspaced short palindromic repeats/Cas9-associated (CRISPR/Cas9) system and a piggyBac transposon that can remove selection cassettes without leaving remnants. In LRRK2-G2019S DA neurons, the percentage of tyrosine hydroxylase (TH)-positive neurons with a total neurite length greater than 2 cm was significantly reduced, and the average branch number was also decreased. These PD-like phenotypes could be rescued by administration of the specific LRRK2 inhibitor LRRK2-IN-1 and by the compound BRF110, which activates the Nurr1:RXRa heterodimer to replenish the DA shortage. Our data suggest that the “footprint- free” LRRK2-G2019S isogenic cell lines allow standardized, genetic background-independent, in vitro PD modeling and are suitable for screening novel drugs that have clinical applications. In addition, we have shown that in vitro TH-positive neurons with a total neurite length greater than 2 cm were positive for serine 129 phosphorylated (S129P) α-synuclein, and we hypothesize that S129P α-synuclein plays a role in the maintenance or formation of long neurites. Thus, we have also provided new insights into the roles of LRRK2-G2019S and S129P α-synuclein in PD pathogenesis. Furthermore, we have optimized CRISPR/Cas9-mediated genomic editing in hiPSCs by establishing a FACS-assisted CRISPR/Cas9 editing (FACE) strategy that uses three fluorescent proteins to isolate biallelic-edited cells with no random integration and by using Exonuclease III (ExoIII)-facilitated long single stranded DNA (ssDNA) donor to reduce random integration. [less ▲]

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See detailAutomated requirements-driven testing of embedded systems based on use case specifications and timed automata
Wang, Chunhui UL

Doctoral thesis (2017)

The complexity of embedded software in safety-critical domains, such as automotive and avionics, has significantly increased over the years. For most embedded systems, standards require system testing to ... [more ▼]

The complexity of embedded software in safety-critical domains, such as automotive and avionics, has significantly increased over the years. For most embedded systems, standards require system testing to explicitly demonstrate that the software meets its functional and safety requirements. In these domains, system test cases are often manually derived from functional requirements in natural language plus other design artefacts, like UML statecharts. The definition of system test cases is therefore time-consuming and error-prone, especially given the quickly rising complexity of embedded systems. The benefits of automatic test generation are widely acknowledged today but existing approaches often require behavioural models that tend to be complex and expensive to produce, and are thus often not part of development practice. The work proposed in this dissertation focusses on the automated generation of test cases for testing the compliance between software and its functional and timing requirements. This dissertation is inspired by contexts where functional and timing requirements are expressed by means of use case specifications and timing automata, respectively. This is the development context of our industrial partner, IEE, an automotive company located in Luxembourg, who provided the case study used to validate the approach and tool described in this dissertation. This dissertation presents five main contributions: (1) A set of guidelines for the definition of functional and timing requirements to enable the automated generation of system test cases. (2) A technique for the automated generation of functional test cases from requirements elicited in the form of use case specifications following a prescribed template and natural-language restrictions. (3) A technique that reuses the automatically generated functional test cases to generate timeliness test cases from minimal models of the timing requirements of the system. (4) A technique for the automated generation of oracles for non-deterministic systems whose specifications are expressed by means of timed automata. In the context of this dissertation, automated oracles for non-deterministic systems are necessary to evaluate the results of the generated timeliness test cases. (5) The evaluation of the applicability and effectiveness of the proposed guidelines and techniques on an industrial case study, a representative automotive embedded system developed by IEE. [less ▲]

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See detailProjectional Editing of Software Product Lines–The PEoPL approach
Behringer, Benjamin UL

Doctoral thesis (2017)

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See detailActive Learning in Cognitive Radio Networks
Tsakmalis, Anestis UL

Doctoral thesis (2017)

In this thesis, numerous Machine Learning (ML) applications for Cognitive Radios Networks (CRNs) are developed and presented which facilitate the e cient spectral coexistence of a legacy system, the ... [more ▼]

In this thesis, numerous Machine Learning (ML) applications for Cognitive Radios Networks (CRNs) are developed and presented which facilitate the e cient spectral coexistence of a legacy system, the Primary Users (PUs), and a CRN, the Secondary Users (SUs). One way to better exploit the capacity of the legacy system frequency band is to consider a coexistence scenario using underlay Cognitive Radio (CR) techniques, where SUs may transmit in the frequency band of the PU system as long as the induced to the PU interference is under a certain limit and thus does not harmfully a ect the legacy system operability. [less ▲]

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See detailDamage detection in prestressed concrete bridges based on static load testing, sagging and modal parameters, using measurements and model updating
Schommer, Sebastian UL

Doctoral thesis (2017)

Bridges are an essential part of nowadays infrastructure to cross natural and artificial obstacles like rivers, valleys or other roads and railways. Many concrete bridges were built in the last 70 years ... [more ▼]

Bridges are an essential part of nowadays infrastructure to cross natural and artificial obstacles like rivers, valleys or other roads and railways. Many concrete bridges were built in the last 70 years. The traffic density has increased immensely over the last decades and the bridges are suffering from corrosion and wear. Nevertheless, the safety of the infrastructure has to be guaranteed and therefore it is very important to find efficient methods for structural health monitoring. For this purpose, visual inspections are the most widely adopted in reality today. Considering the size of most bridge structures, it is understandable that these tests are generally very time-consuming and many personnel are needed, so they are cost-intensive. However, it is not always guaranteed that all damage can be found as only the surface is accessible. For instance, internal damage, such as corrosion of passive reinforcements or prestressed tendons, is difficult to detect. In addition, small cracks can remain undetected when covered by paints or dirt. Therefore, it is important to complement the standard methods with advanced alternatives. The aim is therefore not necessarily to replace visual inspections, but rather to find efficient methods for amendment. An idea being vigorously discussed in the scientific community is based on vibration measurements of a structure to assess its dynamic behaviour. The occurrence of damage will change the system properties, as it changes above all the stiffness distribution. So the system identification process in principle allows detection of changes of eigenfrequencies and hence stiffness. The main problem in practice on real bridges is that the robustness of a method is often insufficient, as the measured parameters are often also influenced by temperature changes. It will be shown that the impact of temperature change, e.g. between night and day, on the system properties is much higher than the influence of small damage. Furthermore, changes in soil and bearing conditions between different seasons can play a role. These environmental effects have to be taken into account while performing measurements for damage assessment. For this purpose, strategies are proposed to compensate environmental effects. Therefore, this thesis focuses on measurements under real environmental conditions, outside a laboratory. Different methods for damage assessment or stiffness tracking based on measured static and on dynamic properties of structures are deployed. Finally, the measured and analysed physical properties of the bridges in this thesis are: eigenfrequencies, mode shapes, sagging under own weight and the deflection line under a static test-loading. These quantities are tracked and artificial damage is introduced stepwise to a test-beam of a real bridge. Damage assessment and localisation is tried directly with the measured quantities but also by model-updating of a finite element model. This solid model is divided in a special way in different slices. It is possible to change the stiffness distribution along the axis of the simulated beam by varying the Young’s moduli of these slices. Furthermore, to reduce the number of free parameters for the subsequent up-dating process, an exponential damage function is introduced that describes the stiffness distribution. At first, the model was designed to fit a healthy reference state. Now measurement data from the artificially damaged test-beam are introduced and the model is updated by changing the Young’s moduli of the slices to minimise a special objective function containing the measured and simulated physical quantities. The comparison of initial and updated model allows a quantification and localisation of damage. Finally, the slice width is reduced around the identified damage region to improve the process. [less ▲]

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See detailObservation and Control of Anaerobic Digestion Processes for Improved Biogas Production
Chaib Draa, Khadidja UL

Doctoral thesis (2017)

In this thesis, we propose a formal modelling framework for the anaerobic digestion process, where we add more degrees of freedom in the control of biogas production. Indeed, we add two additional control ... [more ▼]

In this thesis, we propose a formal modelling framework for the anaerobic digestion process, where we add more degrees of freedom in the control of biogas production. Indeed, we add two additional control inputs to the standardized AM2 (Acidogenesis Methanogenesis, 2 steps) model, re ecting addition of stimulating substrates which enhance the biogas quality and quantity. Then, we describe how the parameters of the resulted nonlinear model can be identi ed, and we analyse the positiveness and boundedness of its state variables. Based on the derived mathematical model and the analysis results, we design di erent software sensors to overcome the lack of reliable and cheap sensors. Indeed, we present a general class of systems to which the considered process model belongs. Then, we design an LMI-based invariant like observer as well as an LMI-based nonlinear observer of the same form as the generalized Arcak's observer. Furthermore, with the aim to render the observer design more robust to disturbances, we include the H1 criterion in its synthesis. Also, to promote the use of the proposed observers in real applications, we extend the methodology to the discrete time case and to the case of nonlinear systems with nonlinear outputs. For the di erent observers design, we use the di erential mean value theorem which allows the transformation of the nonlinear estimation error to a linear parameter varying system. Then, we use the Lipschitz conditions and the Lyapunov standard function to synthesize the stability conditions in the form of linear matrix inequalities. Finally, we enhance the feasibility of the later conditions by using a judicious reformulation of the Young's inequality. In the thesis, we also deal with the process control where we propose a control strategy to track an admissible reference trajectory planned by the plant operator. Moreover, to account for the partial availability of the state vector measurements, we include an exponential nonlinear observer in the control synthesis. Thus, we design an observer based tracking control scheme. To perform the stability analysis of the closed loop system, composed of the system, the observer and the controller, we use the Barbalat's lemma conjointly with the techniques already mentioned for the observers design. Finally, we propose two different methods to compute the controller and the observer parameters. In the first one, we propose to compute them separately. While, in the second one we compute the parameters simultaneously. [less ▲]

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See detailAchtsamkeit als Determinante von Glück im Alter - Theoretische und Empirische Analysen
Theisen, Marie-Paule Gaby UL

Doctoral thesis (2017)

In den späten siebziger Jahren entwickelte der Molekularbiologe und Zen-Praktiker Jon Kabat-Zinn in den USA das „Mindfulness-Based Stress Reduction Program – MBSR“ (dt.: das Programm zur Stressreduzierung ... [more ▼]

In den späten siebziger Jahren entwickelte der Molekularbiologe und Zen-Praktiker Jon Kabat-Zinn in den USA das „Mindfulness-Based Stress Reduction Program – MBSR“ (dt.: das Programm zur Stressreduzierung durch Achtsamkeit). Der Medizinprofessor begann mit Erfolg, das Programm an Schmerzpatienten der University of Massachusetts Medical School Stress Reduction Clinic zu vermitteln. Parallel dazu untersuchte der Forscher die Auswirkungen dieses Stressreduzierungsprogramms auf das psychische und physische Wohlbefinden der Patienten. Diese Forschungsergebnisse veranlassten mich dazu, das bestehende Programm MBSR an die Bedürfnisse und Wünsche von gesunden, existenziell verängstigten, gestressten Menschen im Vorrentenalter und Rentenalter anzupassen und das Programm „Achtsamkeit Entdecken – Leben im Augenblick“ (AELA) für Senioren zu entwickeln. Als theoretische Grundlage dieses Programms wurden einschlägige Theorien zu Achtsamkeit, Glück und dem Alternsprozess beschrieben und in ihrem Zusammenhang elaboriert. Anschließend daran wurden über eine Kombination von quantitativem und qualitativem Vorgehen die Nützlichkeit und die Wirkungen von Achtsamkeit auf das Glücksempfinden „betagter“ Menschen im Alltag untersucht. Im Rahmen einer quantitativ angelegten Trainingsstudie wurden über den Zeitraum von vier Wochen Achtsamkeitselemente vermittelt, die über die Selbstberichte der Teilnehmer evaluiert wurden. Insgesamt zeichneten sich dabei positive Effekte auf das Befinden der Teilnehmer ab und diese betrachteten die Achtsamkeitsübungen als nützlich, um bewusster zu leben. Im Rahmen einer qualitativen Studie wurden fünfzehn Interviews zum Leben im Alter durchgeführt und dabei unterschiedliche Aspekte – wie z.B. Wünsche und Ziele, aber auch Ängste und Befürchtungen – exploriert. In den Interviews wurde zudem erfragt, inwieweit die Personen bereits mit dem Konzept der Achtsamkeit vertraut sind und inwieweit sie dieses nutzen. Auch diese Studie belegt die Bedeutsamkeit dieses Konzeptes für das Leben im Alter. Alle Befunde sprechen somit dafür, dass der gesunde ältere Mensch durch eine regelmäßige Achtsamkeitspraxis – im Sinne eines bewussten Lebens von Augenblick zu Augenblick – Stressfreiheit und Glück erfahren kann.   [less ▲]

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See detailAUTOMATED DEBUGGING AND FAULT LOCALIZATION OF MATLAB/SIMULINK MODELS
Liu, Bing UL

Doctoral thesis (2017)

Matlab/Simulink is an advanced environment for modeling and simulating multidomain dynamic systems. It has been widely used to model advanced Cyber-Physical Systems, e.g. in the automotive or avionics ... [more ▼]

Matlab/Simulink is an advanced environment for modeling and simulating multidomain dynamic systems. It has been widely used to model advanced Cyber-Physical Systems, e.g. in the automotive or avionics industry. To ensure the reliability of Simulink models (i.e., ensuring that they are free of faults), these models are subject to extensive testing to verify the logic and behavior of software modules developed in the models. Due to the complex structure of Simulink models, finding root causes of failures (i.e., faults) is an expensive and time-consuming task. Therefore, there is a high demand for automatic fault localization techniques that can help en- gineers to locate faults in Simulink models with less human intervention. This demand leads to the proposal and development of various approaches and techniques that are able to automatically locate faults in Simulink models. Fault localization has been an active research area that focuses on developing automated tech- niques to support software debugging. Although there have been many techniques proposed to localize faults in programs, there has not been much research on fault localization for Simulink models. In this dissertation, we investigate and develop a lightweight fault localization approach to automatically and accurately locate faults in Simulink models. To enhance the usability of our approach, we also develop a stand-alone desktop application that provides engineers with a usable interface to facilitate localization of faults in their models. [less ▲]

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See detailParkinson's disease: Evaluation of a neuroprotective target and identification of candidate biomarker signatures using murine models
Ashrafi, Amer UL

Doctoral thesis (2017)

Parkinson's disease (PD) is one of the most common age-related neurologic diseases. While existing therapeutic approaches, focusing on dopamine replacement, can alleviate some of the cardinal symptoms ... [more ▼]

Parkinson's disease (PD) is one of the most common age-related neurologic diseases. While existing therapeutic approaches, focusing on dopamine replacement, can alleviate some of the cardinal symptoms, they are associated with severe adverse effects in the long-term. Therefore, identification of new therapeutic interventions to reverse, stop or slow down the progression of Parkinson’s disease is a major focus of PD research. Similarly, identifying reliable biomarkers that would enable early therapeutic intervention is another key area of current research. Here, we evaluated a recently proposed non-dopaminergic protein drug target for PD, Regulator of G-Protein Signaling 4 (RGS4), and performed preliminary studies aimed at the identification of novel biomarker signatures using two murine models of Parkinson’s disease. Recent research on new non-dopaminergic PD drug targets has indicated that inhibition of RGS4, a member of the RGS family of proteins that inactivate G-proteins, could be an effective adjuvant treatment option. However, the effectiveness of RGS4 inhibition for an array of PDlinked functional and structural neuroprotection endpoints had not yet been demonstrated. Here, we used the 6-Hydroxydopamine (6-OHDA) lesioning mouse model to address this question. We observed, using a battery of behavioral and pathological measures, that mice deficient for RGS4 are not protected from 6-OHDA induced injury, and showed enhanced susceptibility in some measures of motor function. Our results suggest that inhibition of RGS4 as a non-dopaminergic target for PD should be approached with caution. In the second part of this study, two alpha-synuclein based PD mouse models, human E46K mutated overexpressed alpha-synuclein and alpha-synuclein fibril spreading models, were used to investigate early pathological events in PD and identify novel candidate biomarker signatures for subsequent validation. Two different time points, before disease onset, and at peak disease manifestation, were analyzed in the two models. Using multiple histopathology and molecular biology techniques, we were able to identify complex changes in patterns of gene expression at early stages of the disease, well before neurodegeneration is detectable. These findings might open venues for new therapeutic strategies and provide insights on the molecular perturbations occurring during the earliest stages of the disease, paving the way for the development of a biomarker signatures for early diagnosis of Parkinson’s disease. [less ▲]

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See detailThe Europeanisation of German, French and Luxembourgish Economic Interest Groups: The Case of the Blue Card Directive Policy-Making Process
Foltête Usage Paris, Sidonie UL

Doctoral thesis (2017)

The Europeanisation of interest groups has been the subject of a substantial academic literature. Yet, multi-level venue shopping has stirred relatively little attention and the cognitive dimension of ... [more ▼]

The Europeanisation of interest groups has been the subject of a substantial academic literature. Yet, multi-level venue shopping has stirred relatively little attention and the cognitive dimension of actors’ Europeanisation has remained largely untouched. This research project addresses these shortcomings by exploring the degree to which business organisations and labour unions deploy their activities at the level of the European Union (i.e. ‘strategic Europeanisation’) and the causal effects of European integration on interest organisations’ shift of perception (i.e. ‘cognitive Europeanisation). This dual perspective is applied to the study of German, French, and Luxembourgish actors’ behaviours in the case of the Blue Card Directive policy-making process. Results on ‘strategic Europeanisation’ reveal a high inclination of German actors to resort to multi-level lobbying in the Blue Card Directive policy-making process and a conversely low propensity of their French counterparts to activate the supranational arena. Luxembourgish stakeholders show very little drive to activate their EU-level lobbying channels. Specific findings point to the importance of financial resources and actors’ domestic embeddedness when deciding whether to make use of Europe, although in contrasted ways. As regards ‘cognitive Europeanisation’, the study shows that the European Union did not shape actors’ shift of perception on labour immigration across the three countries under examination. [less ▲]

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See detailInterpretive Interactions among Legal Systems and Argumentation Schemes
Malerba, Alessandra UL

Doctoral thesis (2017)

This thesis is about argumentation schemes that help to deal with interactions between national and foreign canons of interpretation in private international law cases. In fact, many legal orders, like ... [more ▼]

This thesis is about argumentation schemes that help to deal with interactions between national and foreign canons of interpretation in private international law cases. In fact, many legal orders, like Italy, require that, in conflict of laws disputes, courts apply the relevant foreign law using canons of interpretation and rules of application of the original foreign system. Our research hypothesis is that, in interpreting the foreign rule, domestic courts incur interpretive divergences of many kinds among the involved legal systems. Foreign law interpretation may result in linguistic and/or conceptual misalignments, in normative and/or interpretive gaps, and in specific incompatibilities between inner and foreign canons of interpretation. By focusing on interpretive conflicts within one legal system, legal theorists and AI and Law scholars have not yet paid sufficient attention to the issue, even if pluralist logics and argumentation have been generally applied to legal pluralism and conflict of laws. The present study fills this gap in the literature: it explores the feasibility of a theory for arguing and interpreting in private international law contexts, providing an argument-based conceptual framework that encompasses plausible interpretive interactions. To this end, and after addressing the epistemic concerns foreign law raises for domestic judges, the thesis gives a definition of cross-border interpretive incompatibilities and proposes argumentation schemes to reason with interpretive canons coming from different legal systems. An illustrative list of critical questions is used to evaluate the correctness of such interpretive reasoning. Lastly, the thesis presents the first formal developments of the study, based on the concept of meta-argumentation. It is possible to detect two main contributions to knowledge. First, this work identifies the components of foreign law interpretation, an interpretation activity with significant practical implications for legal systems today. In so doing, it also indirectly contributes to better understand interpretation at large. Secondly, its argument-based analysis paves the way for further formal applications in the domain of AI and Law. [less ▲]

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See detailDevelopment and analysis of individual-based gut microbiome metabolic models
Magnusdottir, Stefania UL

Doctoral thesis (2017)

The human gut microbiota plays a large role in the metabolism of our diet. These microorganisms can break down indigestible materials such as polysaccharides and convert them into metabolites that the ... [more ▼]

The human gut microbiota plays a large role in the metabolism of our diet. These microorganisms can break down indigestible materials such as polysaccharides and convert them into metabolites that the human body can take up and utilize (e.g., vitamins, essential amino acids, and short-chain fatty acids). Disbalances in the gut microbiome have been associated with several diseases, including diabetes and obesity. However, little is known about the detailed metabolic crosstalk that occurs between individual organisms within the microbiome and between the microbiome and the human intestinal cells. Because of the complexity of the intestinal ecosystem, these interactions are difficult to determine using existing experimental methods. Constraint-based reconstruction and analysis (COBRA) can help identify the possible metabolic mechanisms at play in the human gut. By combining mathematical, computational, and experimental methods, we can generate hypotheses and design targeted experiments to elucidate the metabolic mechanisms in the gut microbiome. In this thesis, I first applied comparative genomics to analyze the biosynthesis pathways of eight B-vitamins in hundreds of human gut microbial species. The results suggested that many gut microbes do not synthesize any B-vitamins, that is, they depend on the host’s diet and neighboring bacteria for these essential nutrients. Second, I developed a semi-automatic reconstruction refinement pipeline that quickly generates biologically relevant genome-scale metabolic reconstructions (GENREs) of human gut microbes based on automatically generated metabolic reconstructions, comparative genomics data, and data extracted from biochemical experiments on the relevant organisms. The pipeline generated metabolically diverse reconstructions that maintain high accuracy with known biochemical data. Finally, the refined GENREs were combined with metagenomic data from individual stool samples to build personalized human gut microbiome metabolic reconstructions. The resulting large-scale microbiome models were both taxonomically and functionally diverse. The work presented in this thesis has enabled the generation of biologically relevant human gut microbiome metabolic reconstructions. Metabolic models resulting from such reconstructions can be applied to study metabolism within the human gut microbiome and between the gut microbiome and the human host. Additionally, they can be used to study the effects of different dietary components on the metabolic exchanges in the gut microbiome and the metabolic differences between healthy and diseased microbiomes. [less ▲]

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See detailThe politics of knowledge that govern the European Union lifelong learning policy space – A Foucauldian reading
Rizzo, Stephen UL

Doctoral thesis (2017)

This contemporary historical research calls into question the mentalities that construct the EU lifelong learning policy space in specific ways. By drawing on the Foucauldian concepts of governmentality ... [more ▼]

This contemporary historical research calls into question the mentalities that construct the EU lifelong learning policy space in specific ways. By drawing on the Foucauldian concepts of governmentality and genealogy, this thesis analyses selected main EU lifelong learning policy literature by focusing on how this space has been articulated in governable forms. In line with a Foucauldian interpretation of power, the EU as a subject is decentred and considered as an epistemological form of assumption so that power and knowledge are analysed according to how they operate in this space. The governmentalist approach explores the technologies of the self and the technologies of government that construct and govern the conduct of conduct of the subject through the recurrent narratives in this space. In combination with this approach, the genealogical analysis of the episteme lifelong learning traces the different terminological interpretations which have been systematically reconfigured throughout the years to attain new connotations. These different connotations are problematised not only because the distinctiveness of the definition influenced the trajectory lifelong learning took throughout the years, but also because lifelong learning can, at one and the same time, control or liberate people. The distinctive contribution to academic literature that this thesis achieves is that it problematises the unquestionable truths that construct the EU lifelong learning policy space from a non-normative point of view. The overriding idea is for the actors in this space to make visible the taken-for granted principles and to create the possibility to challenge prevailing power relations and challenge what is uncritically taken as natural. [less ▲]

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See detailComputational Aspects of Classical and Hilbert Modular Forms
van Hirtum, Jasper UL

Doctoral thesis (2017)

The main topic of this thesis is the study of classical and Hilbert modular forms and computational aspects of their q-expansions. The coefficients of q-expansions of eigenforms are particularly ... [more ▼]

The main topic of this thesis is the study of classical and Hilbert modular forms and computational aspects of their q-expansions. The coefficients of q-expansions of eigenforms are particularly interesting because of their arithmetic significance. Most notably, modular forms are an essential ingredient in Andrew Wiles’s proof of Fermat’s last theorem. This thesis consists of two parts: the first part concerns the distribution of the coefficients of a given classical eigenform; the second part studies computational aspects of the adelic q-expansion of Hilbert modular forms of weight 1. Part I of this thesis is an adapted version of the article On the Distribution of Frobenius of Weight 2 Eigenforms with Quadratic Coefficient Field published in Experimental Mathematics [38]. It presents a heuristic model that settles the following question related to the Sato-Tate and Lang-Trotter conjectures: given a normalised eigenform of weight 2 with quadratic coefficient field, what is the asymptotic behaviour of the number of primes p such that the p-th coefficient of this eigenform is a rational integer? Our work contributes to this problem in two ways. First, we provide an explicit heuristic model that describes the asymptotic behaviour in terms of the associated Galois representation. Secondly, we show that this model holds under reasonable assumptions and present numerical evidence that supports these assumptions. Part II concerns the study of (adelic) q-expansions of Hilbert modular forms. Our main achievements are the design, proof and implementation of several algorithms that compute the adelic q-expansions of Hilbert modular forms of weight 1 over C and over finite fields. One reason we are studying such q-expansions is that their coefficients (conjecturally) describe the arithmetic of Galois extensions of a totally real number field with Galois group in GL 2 (F p ) that are unramified at p. Using the adelic q-expansions of Hilbert modular forms of higher weight, these algorithms enable the explicit computation of Hilbert modular forms of any weight over C and the computation of Hilbert modular forms of parallel weight both over C and in positive characteristics. The main improvement to existing methods is that this algorithm can be applied in (partial) weight 1, which fills the gap left by standard computational methods. Moreover, the algorithm computes in all characteristics simultaneously. More precisely, we prove that, under certain conditions in higher weight, the output of the algorithm for given level N and quadratic character E includes a finite set of primes L such that all Hilbert modular forms of given parallel weight, level N and quadratic character E over F p are liftable for all primes p outside the set L. In particular, testing primes in the set L enabled the computation of examples of non-liftable Hilbert modular forms of weight 1. [less ▲]

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See detailStudent-driven Inquiry-based Science Education in Luxembourg Primary School Contexts
Dombkowski-Wilmes, Sara Elizabeth UL

Doctoral thesis (2017)

This study examined the use of a student-driven inquiry-based science education instructional approach designed specifically to meet the contextualized needs of Luxembourg primary schools. The key issues ... [more ▼]

This study examined the use of a student-driven inquiry-based science education instructional approach designed specifically to meet the contextualized needs of Luxembourg primary schools. The key issues, namely an increasing linguistically diverse student population and limited instructional time for science, were considered in the design of the instructional approach. Drawing on theories of dialogic inquiry, the instructional approach engages students in asking questions and designing investigations to build their science understanding. This interpretive qualitative study utilized a multi-perspective approach to analyse how teachers used the instructional approach in their classrooms and explored two overarching research questions, first, what instructional opportunities does Science Workshop, an inquiry-based student-driven science instructional approach, afford when used in Luxembourg primary classrooms? And second, what does analysis of interactions in these contexts reveal about inquiry-based science instruction in multilingual classrooms? Qualitative methodologies, specifically case studies of classroom implementation, were used to examine the use of the program teachers’ adaptations of the program in their classrooms. Bakhtinian notions of heteroglossia and dialogic pedagogies were used as lenses to examine the instructional opportunities afforded. Interaction analysis was used to examine instruction in a focal classroom when the inquiry-based approach was used. Analyses rooted in sociocultural theoretical frameworks of science and language learning revealed three key contributions toward the use of IBSE in Luxembourg primary schools. First, the key characteristics of teacher professional learning opportunities that supported teachers’ use of the program in Luxembourg, which included workshops, material support, and opportunities to share implementation cases were identified. Second, the ways in which ritualized instructional components afford students spaces to engage on micro-scales in building synchronous interactions during science investigations were revealed. Third, that the science notebooks can position students to engage in dialogic discussions surrounding science investigations was shown through detailed analysis. Taken together, these interrelated points contribute to an understanding of the use of student-driven instructional approaches in multilingual science classrooms in general, while revealing implications for the use of inquiry-based science instructional approaches in Luxembourg primary schools specifically. [less ▲]

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See detailDynamic Career Attitudes And Life Satisfaction Among CEDIES' Postgraduates From Luxembourg
Karavdic, Senad UL

Doctoral thesis (2017)

Introduction: With an ever increasing number of university students and the employment shift from an opportunity to insecure development, new postgraduate generations have to be amenable to continuous ... [more ▼]

Introduction: With an ever increasing number of university students and the employment shift from an opportunity to insecure development, new postgraduate generations have to be amenable to continuous upgrading, complete with a wide range of skills in the promotion of their career development. Keeping in mind that the job market and work environment are variables that are mostly changing, the possession of an active career attitude may be a guarantee for postgraduates’ employability and their career outcome. Giving importance to the adjustment during the transitional period, life satisfaction (LS) may be altered based on the discrepancy between career aspiration and career achievement. Among university postgraduates, the main objectives of our doctoral work are to (1) measure the associations between dynamic career attitudes (DCA), generic employment capabilities and socioeconomic factors (2) determine the underlying structure of DCA, protean career orientation and career goal (3) analyze relations between DCA dimensions and career factors such as career goals, protean career orientation and LS (4) evaluate the effects of DCA dimensions on LS for native and non-native Luxembourgish postgraduates. Method: A survey was conducted among 2800 participants registered at the Centre for Documentation and Information on Higher Education (CEDIES). Data collection was realized via an information flyer that was sent to the home addresses of the postgraduates and that contained instructions about the aims of the study and a link to the survey. The postgraduates could directly access the anonymous online questionnaire in either French or English. To explore the associations and relations between variables student t-tests and bivariate correlations were used. Exploratory factor analysis was conducted to identify the underlying relationships between measured DCA dimensions, protean career orientation and career goals. In order to determine the statistical significance of the indirect effect for the mediation analysis, the bootstrapped confidence interval on 1000 bootstrap samples was used. A multiple logistic regression was applied to each group, but only significant variables (p<0.05) were introduced into the regression models. Results: A total of 644 volunteers completed the self-assessment questionnaire online. Majority of the participants were female, students and not employed. Postgraduates with high employment capabilities tend to present a higher dynamic career score that has been identified as a construct of four career dimensions (career adaptability, career optimism, career related knowledge and career planning). Each dimension was mediated from self-directed career dimension of protean career orientation by intrinsic career goal. Career adaptability and career optimism predicted both, happiness and LS. However, this relationship seems only to be presented for ‘postgraduates that are still studying. In the same vein, the DCA dimension of career optimism has been associated to LS by native Luxembourgers, whereas perceived financial situation intervenes in explanation of LS by non-native postgraduates. Discussion and Conclusion: The Dynamic Career Attitudes scale appears to be a relevant instrument in evaluating disparities in employment capabilities among postgraduates. Our findings indicated the application of intrinsic career goal in the development of career attitudes, where career adaptability and career optimism explained the highest proportion of the variance related to LS. The acquisition of qualitative information on DCA from a comparable population at different stages (from career goals aspirations and the process toward career goal accomplishments), could be rendered more straightforward for future research. Finally, it could be interesting to assess the DCA of university graduates during and after their Master’s degrees; before they start work and in the early years of their careers. Contextualizing our findings, the differences of native Luxembourgish and non-native postgraduates don't differ in LS, however, it seems to be influenced by different variables such as financial situation suggesting the introduction of the social grant of CEDIES for the most disadvantaged students. Practical implications are also suggested. Promoting programs proposed by University services towards counseling and an accompaniment to their career attitudes may enhance postgraduates’ LS which are major indicators for a successful mobility. [less ▲]

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See detailMonographie : Superviseur, psychanalyste ou agent pastoral ?
Weber, Jean-Marie UL

Dissertation and these (2017)

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See detailArbeiten unter Hitler. NS-Sozialpolitik und Herrschaftspraxis im besetzten Luxemburg 1940-1944
Schoentgen, Marc Mike Claude UL

Doctoral thesis (2017)

Die Arbeit untersucht Grundlagen, Konzeptionen und Auswirkungen der nationalsozialistischen Besatzungsherrschaft in Luxemburg (1940-1944) in den Bereichen der Wirtschafts- und Sozialpolitik ... [more ▼]

Die Arbeit untersucht Grundlagen, Konzeptionen und Auswirkungen der nationalsozialistischen Besatzungsherrschaft in Luxemburg (1940-1944) in den Bereichen der Wirtschafts- und Sozialpolitik. Berücksichtigung findet auch die NS-Volkstums- und Kulturpolitik. Staatliche Maßnahmen führten in der Besatzungszeit dazu, dass während einer relativ langen Phase die Auswirkungen des Krieges auf das Alltags- und Arbeitsleben wenig spürbar waren. Damit trug die Sozialpolitik zu einer politischen und psychologischen Stabilisierung des Regimes bei. Besonders betroffen von der Politik des nationalsozialistischen Gauleiters Gustav Simon waren die Luxemburger Gewerkschaften, die von den Machthabern instrumentalisiert und anschließend liquidiert wurden. An ihre Stelle trat die Deutsche Arbeitsfront, größte Massenorganisation des Regimes, die ihre vielfältigen Aktivitäten in den Bereichen der Sozial-, Wirtschafts-, Freizeit- und Kulturpolitik auch auf Luxemburg ausdehnte. Genauer untersucht wird die Institution des Stillhaltekommissars für das Organisationswesen, der die Gewerkschaften und andere Vereine liquidierte beziehungsweise nazifizierte. Damit wurden die Fundamente der Luxemburger Gesellschaft in Frage gestellt. Die Neuordnungspolitik des Regimes wird u.a. am Beispiel des Industriegebiets im Süden Luxemburgs dargestellt. Im Arbeitermilieu sahen die nationalsozialistischen Machthaber ein Experimentierfeld ihrer Politik. Krieg und Besatzung hatten letztlich auch Auswirkungen auf die großen Industriebetriebe. Gerade hier änderte sich ab der zweiten Hälfte des Krieges durch unterschiedliche Formen der Repression und Zwangsarbeit der Alltag der Menschen. Übergreifend befasst sich die Arbeit auch mit der Luxemburger Kriegsgesellschaft beziehungsweise den unterschiedlichen Reaktionen der Arbeiter und Angestellten auf Verlockung und Zwang. Kapitel: 1. Die NS-Sozialpolitik in Luxemburg 2. Die Luxemburger Gewerkschaften im Krieg. 3. Das Luxemburger Industriegebiet 4. Der Stillhaltekommissar für das Organisationswesen 5. Die Deutsche Arbeitsfront 6. Arbeiten im Krieg [less ▲]

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See detailLe Luxembourg aux origines de l'OTAN (1948-1953)
Lafontaine, Aurélia UL

Bachelor/master dissertation (2017)

The aim of the master thesis "Le Luxembourg aux origines de l'OTAN (1948-1953)" is twofold. On the basis of a theoretical model studying the behaviour of Luxembourg as a small state in multilateral ... [more ▼]

The aim of the master thesis "Le Luxembourg aux origines de l'OTAN (1948-1953)" is twofold. On the basis of a theoretical model studying the behaviour of Luxembourg as a small state in multilateral organisations, the thesis intends to analyse the Grand-Duchy's strategy in the negotiations leading to the creation of NATO and its first years of existence. In the second part, the research focusses on how the country's membership in the Transatlantic Alliance impacted its domestic policy. [less ▲]

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See detailAspekte der luxemburgischen Syntax
Döhmer, Caroline Elisabeth UL

Doctoral thesis (2017)

Das Ziel dieser Arbeit ist eine empirische und systematische Beschreibung ausgewählter syntaktischer Phänomene im Luxemburgischen. Im Vordergrund der deskriptiven Analyse stehen vier Themenbereiche ... [more ▼]

Das Ziel dieser Arbeit ist eine empirische und systematische Beschreibung ausgewählter syntaktischer Phänomene im Luxemburgischen. Im Vordergrund der deskriptiven Analyse stehen vier Themenbereiche: Kasussyntax und -funktionen (Genitiv, Possession, Partitiv), Pronominalsyntax (Syntax und Semantik von Personalpronomen), Verbcluster (2-, 3- und 4-gliedrige Cluster im Nebensatz) sowie die syntaktischen Eigenschaften von Nebensatzeinleitungen (Kongruenz und Verdopplungen). Die Arbeit soll einerseits dazu beitragen, die luxemburgische Sprache in ihren strukturellen Eigenschaften besser verstehen zu können und andererseits die (syntaktische) Erschließung des Kontinentalwestgermanischen weiter voranbringen. Somit liefert diese Dissertation einen wichtigen Beitrag in der derzeit aufblühenden Forschungsrichtung der linguistischen Luxemburgistik und ordnet sich gleichzeitig in die allgemeine westgermanische Syntaxforschung ein. [less ▲]

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See detailComparative study of reduced-order methods for geometrically nonlinear structures
Khurshudyan, Amalya UL

Doctoral thesis (2017)

The dissertation is devoted to the comparison and development of techniques for model order reduction (MOR) of geometrically nonlinear elastic structures in the static limit. The MOR procedure works in ... [more ▼]

The dissertation is devoted to the comparison and development of techniques for model order reduction (MOR) of geometrically nonlinear elastic structures in the static limit. The MOR procedure works in the following way: the structure is first discretized into finite elements and a discretized system of algebraic equations is obtained, in which the stiffness matrix depends on the unknown vector. The system is then projected to a lower order space. The choice of the basis of the projection space is made according to the methods developed in the thesis. To this end, three techniques are developed here based on different choices of the basis functions. Comparative analysis of the suggested methods is carried out in the case of two-dimensional structures (Euler-Bernoulli beam, multi-span beam and frame). In order to be able to compare the results with those obtained by the MOR techniques which are developed, the benchmark problems which are examined are first solved analytically. Results of computations carried out in Python and are then discussed. [less ▲]

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See detailVERHALTEN AUSGEWÄHLTER NANOPARTIKEL IN KOMMUNALEN KLÄRANLAGEN UNTER BESONDERER BERÜCKSICHTIGUNG DER ANAEROBEN SCHLAMMBEHANDLUNG
Rahimi, Anahita Bahareh UL

Doctoral thesis (2017)

The increasing use of nanoparticles and the market to commercialize this innovative technology requires a deeper understanding of the behavior of nanoparticles (NPs) and the resulting consequences in an ... [more ▼]

The increasing use of nanoparticles and the market to commercialize this innovative technology requires a deeper understanding of the behavior of nanoparticles (NPs) and the resulting consequences in an environmentally The increasing use of nanoparticles and the market to commercialize this innovative technology requires a deeper understanding of the behavior of nanoparticles (NPs) and the resulting consequences in an environmentally relevant matrix. However, since the fate and behavior of nanoparticles is largely unknown to the environment, this study was done to investigate the key properties of nanoparticles, parameters to describe them and to discuss how these parameters can influence their fate and behavior in the natural environment. The core goal of this discussion is to relate sludge treatment to relevant properties of the nanoparticle, which may interact with a range of substances naturally present in wastewater treatment plants (WWTPs) and activated sludge. Understanding these properties is necessary for interpreting the fate of nanoparticles and predicting their effects in the actual environment. Environmentally matrix are challenging to investigate, for instance as in sludge and anaerobic sludge stabilization. According to the literature, it will be assumed that about 95% of the NPs entering the WWTP end up in the sludge. This work reports on the investigation and observation of NPs behavior in the different stages, using different experiments and metering devices. The different experiments include (i) characterization of NPs before their application (NanoSight), (ii) behavior analysis in terms of kinetic transformations (Turbiscan), (iii) long- and short-term analysis of NPs effects on anaerobic sludge stabilization (laboratory fermentation plants). The characterization represents the current size distribution of the NPs in a controlled environment (H2O). Size is one of the defining properties of NPs, which causes changes in physical and chemical properties of NPs compared to their original materials. The results show that the distribution of NPs depends on the type of particle, surface coating and dispersion concentration. These parameters are subject to permanent changes in sludge. That is why an exact allocation to the effects seems almost impossible. Characterization is indispensable for the subsequent comprehension of the effects, and for the understanding of findings, which may result from the behavioral analysis, as well as from the effect analysis. The behavioral analysis was carried out by Turbiscan technology to consider relevant sludge parameters and substances (Chemical Oxygen Demand COD, Polymers, Humic acids, digestion process) to the behavior of NPs in sludge. The initial aim was to progressively add of representative substances to approximate the experiment to natural conditions. The phase separation detection identified a clear sedimentation behavior in all samples. To explain this and the kinetic modification as well as the resultant kinetic instability, the NPs’ diameter (particle size detection) were studied. The more instable samples had often smaller diameters. The substances within the sludge seem to influence the kinetic stability of NPs. This could be caused by the dynamic corona (active interaction with environment) and hard corona (strongly bound and restrained interaction with environment) formation, as well as agglomeration or modification of surface charges. Changes in kinetic stability means changes in the behavior and fate of NPs in such an environmental media like sludge. However, since the sludge is filtered for the behavioral analysis, the microorganism’s role is neglected. In order to complete the behavioral analysis considering the microorganism’s contribution, the consequences of the NP-behavior are measured as effects under various realistic conditions. The effects of NPs’ behavior on the anaerobic microorganisms were investigated based on their potential and efficiency in anaerobic sludge stabilization for gaining additional insights. The long-term effects of NPs in sludge treatment plants (STP) were investigated using four parallel pilot reactors operated under identical conditions, with daily feeding (substrate and two different NP-concentration). There was a temporary decrease of Biogas especially at the third phase (second concentration) except for the ZnO-reactor while the proportion of methane remained stable. Based on the knowledge obtained from the characterization and behavioral analysis, this might be due to the kinetic transformation of NPs. When the particle size for instability is exceeded as a consequence of surface changes and agglomerations, rapid sedimentation occurs. After eliminating the NP-reactivity and obtaining NP-agglomerations, NPs are extracted from the digestion system (sedimentation). Due to that, the microorganisms are able to operate to their full potential and efficiency, which is an indication of extracellular inhibition and preclude probably the intracellular inhibition caused by ions release. The short-term effects of ENPs in batch experiments were investigated under identical conditions. Furthermore, oxygen was used as an inhibitor to intensify the NP’s effects on the anaerobic microorganisms and digestion process. Oxygen is toxic for anaerobic microorganisms and enhance the release of ions. NP-effects were evaluated for methane yield. It will be assumed that the corona formations created by the sludge substances, reduce the release of ions and the NP-toxicity, even after decreasing the biomass. In addition, the NPs are able to eliminate O2 as an inhibitor, as well as positively influence the production dynamics and methane yield. To sum up, the growing interest in nanoparticles and their potential has presented many challenges for science, in toxicology and innovative technologies. These challenges bring new questions related to understanding NPs and their interplay with certain circumstances. A considerable contribution has been made for understanding the behavior of nanoparticles in the environmentally relevant media. However, a partial understanding for the fate of nanoparticles in complex matrices has been gained. As the nanoparticles themselves are such a complex matter, they require more research in developing a more complete understanding of the way they function. Having this knowledge would enable to explore progressively their behavior and fate in complex matrices.. [less ▲]

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See detailSecond language learners’ self-initiated topic changes during book-related activities in preschool and their impact on Luxembourgish proficiency
Wirtz, Delia UL

Doctoral thesis (2017)

The present research traces the second language learning process in Luxembourgish during book related activities by 4- to 5-year old pre-schoolers with Portuguese, Cap Verdean and Brazilian origins. With ... [more ▼]

The present research traces the second language learning process in Luxembourgish during book related activities by 4- to 5-year old pre-schoolers with Portuguese, Cap Verdean and Brazilian origins. With 47,2% of the preschool population being of foreign origins, the Lusophone community forms the largest group with 24,1%. This salient fast growing multilingual and multicultural population learns Luxembourgish for integration and everyday interaction and, hence, challenges public education with its diverse and altering demands. The present study enlarges second language research in the Luxembourgish context and links to previous investigation on topics, however, by taking a pragmatic stance towards topics. Through the foregrounding of the local topic management as well as its impact on activities, which are less teacher controlled, the study pictures second language learning as a product of co-constructed interaction. The focus lies on the negotiation of story meaning through self-initiated topic changes during three book related activities: Joint reading, storytelling and play. The data consists of video recorded lessons and on stimulated recall interviews with the teachers. A multi-method framework is used to investigate pupils’ interaction and language learning processes. From a quantitative point of view, the study analyses how pupils’ utterance length varies according to the openness of the lesson by allowing self-initiated topic changes as well as the design of the book activity (1) led by teachers or (2) by the pupils. From a qualitative stance, a sequence-by-sequence analysis of the jointly constructed narrative identifies the interactional dynamics of the collaborative storytelling activities and the use of self-initiated topic changes which children draw upon to express themselves more freely. The results show that children’s utterances vary according to the activity type. Pupils produce longer utterances, when they can self-initiate a topic hereby boosting their second language proficiency – either because the teacher is withdrawing or because the participation framework is open enough for them to make creative use of the language. The children also show their capability of successfully managing topic changes without the presence of the teacher while at the same time co-constructing the meaning of the story and paying attention to lexical details. The interviews reveal the teachers’ astonishment for the degree of pupil participation as well as their pedagogical practices. Implications from the analysis are gathered in a theoretical model that links opportunities for self-initiated topic changes to language proficiency. Recommendations for a more active pupil participation during book related activities point to sense-making, joint topic negotiation and story enactment. [less ▲]

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See detailCryptanalysis, Reverse-Engineering and Design of Symmetric Cryptographic Algorithms
Perrin, Léo Paul UL

Doctoral thesis (2017)

In this thesis, I present the research I did with my co-authors on several aspects of symmetric cryptography from May 2013 to December 2016, that is, when I was a PhD student at the university of ... [more ▼]

In this thesis, I present the research I did with my co-authors on several aspects of symmetric cryptography from May 2013 to December 2016, that is, when I was a PhD student at the university of Luxembourg under the supervision of Alex Biryukov. My research has spanned three different areas of symmetric cryptography. In Part I of this thesis, I present my work on lightweight cryptography. This field of study investigates the cryptographic algorithms that are suitable for very constrained devices with little computing power such as RFID tags and small embedded processors such as those used in sensor networks. Many such algorithms have been proposed recently, as evidenced by the survey I co-authored on this topic. I present this survey along with attacks against three of those algorithms, namely GLUON, PRINCE and TWINE. I also introduce a new lightweight block cipher called SPARX which was designed using a new method to justify its security: the Long Trail Strategy. Part II is devoted to S-Box reverse-engineering, a field of study investigating the methods recovering the hidden structure or the design criteria used to build an S-Box. I co-invented several such methods: a statistical analysis of the differential and linear properties which was applied successfully to the S-Box of the NSA block cipher Skipjack, a structural attack against Feistel networks called the yoyo game and the TU-decomposition. This last technique allowed us to decompose the S-Box of the last Russian standard block cipher and hash function as well as the only known solution to the APN problem, a long-standing open question in mathematics. Finally, Part III presents a unifying view of several fields of symmetric cryptography by interpreting them as purposefully hard. Indeed, several cryptographic algorithms are designed so as to maximize the code size, RAM consumption or time taken by their implementations. By providing a unique framework describing all such design goals, we could design modes of operations for building any symmetric primitive with any form of hardness by combining secure cryptographic building blocks with simple functions with the desired form of hardness called plugs. Alex Biryukov and I also showed that it is possible to build plugs with an asymmetric hardness whereby the knowledge of a secret key allows the privileged user to bypass the hardness of the primitive. [less ▲]

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See detailWelche Organisationsformen produzieren Wissenschaft? Expansion, Vielfalt und Kooperation im deutschen Hochschul- und Wissenschaftssystem im globalen Kontext, 1900-2010
Dusdal, Jennifer UL

Doctoral thesis (2017)

Overview and introduction “Which organizational forms produce science? Expansion, diversity, and cooperation in Germany's higher education and science system embedded within the global context, 1900-2010” ... [more ▼]

Overview and introduction “Which organizational forms produce science? Expansion, diversity, and cooperation in Germany's higher education and science system embedded within the global context, 1900-2010”. Already the title of my dissertation manifests an approach that examines the topic of the development of scientific productivity in the German higher education and science landscape from different perspectives: levels, dimensions, and an extensive timeframe. Deriving from and contributing to the international research project “Science Productivity, Higher Education, Research and Development, and the Knowledge Society” (SPHERE), my research focuses on the investigation of the influence of higher education development and science capacity-building on scientific knowledge production, globally, comparatively, and considerable depth for Germany, a key science producer for well over a century. Focusing mainly on the different structures and institutional settings of the German higher education and science system, the dissertations shows how these affected and contributed to the long-term development of scientific productivity worldwide. The historical, comparative, and in-depth analyses are especially important in light of advancing globalization and internationalization of science, stronger networks of scientists worldwide, and the emergence of the “knowledge society”. The research design combines macro- and meso-level analyses: the institutionalized and organizational settings in which science is produced. Since information about single authors was limited in availability, extensive micro-level analyses were not possible here, yet the research articles analyzed were all written and published by individuals working in organizations, which are in the center of analysis here. By reference to the dimensions expansion, diversity, and cooperation, I elaborated the frame of my investigation, and sorted my research questions, including country, organizational field and form, and organizational levels. The structure of this work (see outline) addresses these themes and the observed timeframe spans the years from 1900 to 2010 – more than a century (see section 1.2). My main goal was to investigate how and why scientists publish their research results in peer-reviewed journal articles. The point is to emphasize the importance of scientific findings/discoveries, because non-published results are non-existent for the scientific community. From the ways and in which formats scientists publish their work, we can deduce how science is organized (within and across disciplines). My dissertation analyzes publications in peer-reviewed journals, because they are the most important format – alongside patents in applied fields – to disseminate new knowledge in science, technology, engineering, mathematics, and health (hereafter STEM+ fields). Articles not only record new knowledge, but also contribute to the reputation of researchers and their organizations. Journal publications in reputable journals with peer-review have become the “gold standard” measure of scientific productivity. Within the last several decades, the scientization of many dimensions of societal life proceeded, and the generation of new knowledge increasingly became the focus of political, economic, and social interests – and research policymaking. Therefore, it is important to identify the institutionalized settings (organizations/organizational forms) in which science can best be produced. Here, the diverse types of organizations that produce science – mainly universities, research institutes, companies, government agencies and hospitals – were identified and differences and similarities of these organizational forms were analyzed on the basis of their character, goals, tasks, and the kinds of research their members produce. In a first step, I show why I structured my work at the interface of higher education research, science studies, and bibliometrics (see chapters 2 and 5). Analyzing publications is still the key task of bibliometrics, but the results are used by many other actors as well: higher education managers, politicians, and scientists themselves to make claims about the quality of science, to compare each other, or to influence the structure, organization, and output of the higher education and science system. While it is difficult to make direct statements about the quality of research on the basis of simply counting the number of research articles a scientist publishes, the quality of journals is used as a proxy to compare across disciplines. To measure quality, other parameters are necessary. Thus, here statements focus on the quantity of science produced, not on the intrinsic quality of the analyzed research articles, the specific research achievements of individual scholars, organizations or organizational forms, or even countries. Nevertheless, output indicators elaborated here definitely show the huge expansion of scientific production and productivity, the stability of the research university over time as the most important science producer in Germany, but also rising differentiation and diversification of the organizational forms contributing to overall scientific output. Furthermore, the start of a considerable and on-going rise in national and international collaborations can be dated to the early 1990s. The chapter about the multidisciplinary context (see chapter 2) discusses the relationship between higher education research and science studies in Germany as well as the special position of scientific knowledge in comparison to other forms of knowledge. Scientific knowledge is generated, distributed, and consumed by the scientific community. To get an overview about the most important studies in the field, and to contextualize my work within the already existing empirical studies, I describe the current state of research in chapter 3. Research questions Section 1.2 provides a detailed description of my research questions: Which organizational forms produce science? 1. How has worldwide and European scientific productivity developed between 1900 and 2010 in comparison? 2. How has the German higher education and science system been embedded in the global developments of higher education and science over time? 3. How has scientific productivity in Germany developed between 1900 and 2010? 4. Among all science-producing organizational forms, what do the key organizational forms contribute to scientific productivity? 5. Which organizational forms provide the best conditions for scientific productivity? 6. Which single organizations produce the most research in Germany? 7. What is the impact of increasing internationalization of research on national and international cooperation, measured in publications in scientific journals? Theoretical framework Theoretically (see chapter 4), I apply a neo-institutional (NI) framework to explore and explain both the tremendous expansion of higher education and science across the world and considerable differences across time and space in the institutional settings, organizational forms, and organizations that produce scientific research in Germany. Sociological NI focuses on understanding institutions as important in guiding social action and shaping processes of social development. Such an approach emphasizes the development, functioning, and principles of institutions. Milestones in NI describe the nexus of organization and society supposing that organizational structures express myths and reflect ideals institutionalized in their environment. While capturing, copying, and asserting these, structural similarity (institutional isomorphism) between organizations in society will be established. The concept of “organizational field” emphasizes relationships between organizations within an environment. Organizational fields (communities) consist of all relevant organizations. In section 4.1.2 I discuss the differences between institutions and organizations and the difficulty of a distinction of the terms, especially in German-speaking sociology, which does not distinguish clearly between these terms. Fundamentally, NI approaches differ in the dimensions or pillars and levels of analysis they privilege (see figure 5, p. 80), but they share fundamental principles and the theoretical framework. Thus NI is particularly suitable for a multi-level analysis of scientific productivity across time and space. The historical development of the German higher education and science system must analyzed considering also global developments, because on the one hand it had an enormous impact on the development of other systems worldwide, and, on the other hand, global trends affect the on-going institutionalization and organization(s) of science in Germany. Intersectoral and international cooperation is growing and becoming increasingly important, leading to diverse networks within and between higher education and science systems worldwide. The classical, national case study is hardly longer possible, because macro units like countries are highly interdependent, embedded in global, regional and local relationships, such that borders between the global and the national dimension are increasingly blurred. Nevertheless, countries are units with clearly defined boundaries and structures, thus they can be handled as units to compare. The theoretical perspectives and different levels of analysis addressed here are displayed in Figure 5. I apply the “world polity” approach as a broader lense with which to make sense of the truly global arena of higher education and science (macro level). The focus of this perspective is on global and international structures and processes, which developed over time. Through this perspective, I explore global diffusion and formal structures of formal principles and practical applications. Combining historical and sociological institutionalism helps to focus on developments and processes over time on the meso level, to explain how institutions have developed and change(d). The concepts of “critical junctures” and path dependencies are useful to explain these processes over time. To describe the transformation of knowledge production over the entire twentieth century, and to analyze different organizational forms that produce science in Germany, two prevalent theoretical concepts are discussed: Mode 1 versus Mode 2 science, and the Triple-Helix model to describe the relationship between science, industry and state. In “The New Production of Knowledge” Michael Gibbons and his colleagues describe the transformation of knowledge from an academic, disciplinary, and autonomous – “traditional” – organization of science (Mode 1) with a focus on universities as the key organizational form, to a more applied, transdisciplinary, diverse, and reflexive organization of science (Mode 2) that features a more diverse organization of science, relying on a broader set of organizations producing knowledge. Within the literature, debates center on whether this new model has replaced the old, and which of these models best describes the contemporary organization of science (here: the STEM+ fields). In turn, the Triple-Helix model preserves the historical importance of the universities. This approach assumes that future innovations emerge from a relationship between universities (production of new knowledge), industry (generation of wealth), and state (control). Data and methods In these analyses, only peer reviewed journal publications were used – as the best indicator for measuring the most legitimated, authoritative produced science. This focus enabled an investigation of publications in-depth and over a 110 year timeframe. Research articles in the most reputable, peer-reviewed, and internationally reputable journals are the gold standard of scientific output in STEM+. The data I used is based on a stratified representative sample of published research articles in journals in STEM+-fields. My measure relies on the key global source for such data, the raw data from Thomson Reuters’ Web of Science Science Citation Index Expanded (SCIE) (the other global database is Elsevier’s Scopus, which also indexes tens of thousands of journals), which was extensively recoded. Methodologically, my approach is based on a combination of comparative institutional analysis across selected countries and historically of the German higher education and science system, and the systematic global evaluation of bibliometric publication data (see chapter 6). The SCIE includes more than 90 million entries (all types of research), mainly from STEM+-fields. I focus on original research articles, because this type of publication contains certified new knowledge. The SPHERE dataset covers published research articles from 1900 to 2010. From 1900 to 1970, we selected data in 5-year-steps in the form of a stratified representative sample. From 1975 onwards full data is available for every year. Depending on the research question, either five or ten-year steps were analyzed. A detailed description of the sampling and weighting of the data can be found in chapter 6. In consideration of the criteria above, I analyzed 17,568 different journals (42,963 journals were included into the database if we count the same journals in different years), and a total of 5,089,233 research articles. To prepare the data for this research, it had to be extensively cleaned and coded. Very often our international research team found missing information on the country level and/or on the level of organizations/organizational forms. From June 2013 to December 2015, research in the archives of university libraries was necessary to manually add missing information, particularly organization location and author affiliations. In the field of bibliometrics, we find different methods to count publications. In this work, I mainly apply the “whole count” approach (see table 1, p. 126). This decision is based on the assumption that every author, organization, or country contributed equally to a publication. An overestimation of publications can’t be precluded, because research articles are counted multiple times, if a paper is produced in co-authorship, which has been rising worldwide over the past several decades. The absolute number of publications (worldwide, Europe, Germany) is based on a simple counting of research articles (without duplicates, in cases of co-authored articles). Summary of the most important results The empirical part of my work is divided into three parts. In the following sections, I will present the most important findings. The global picture – higher education and science systems in comparison The central question of my research project was “which organizational forms produce science”? For a better understanding and classification of the results of my case study, I embedded the German higher education and science system into the European and global context. I answered the questions “how did the worldwide and European scientific productivity developed between 1900 and 2010 in comparison”, and “how was/is the German higher education and science system embedded in global developments of higher education and science over time” as follows: First, I show that the worldwide scientific growth followed a pure exponential curve between 1900 and 2010 (see figures 3 and 10; pp. 50, 147) – and we can assume that this strong upward trend continues today. The massive expansion of scientific production had and still has a tremendous influence on societal developments, beyond simply economic and technical developments, but rather transforming society. I show that higher education and science systems worldwide exhibit communalities, which have led to similar developments and expansion of scientific productivity. The comparison of important European countries (Germany in comparison with Great Britain, France, Belgium and Luxembourg) uncovered the contribution of the development and spread of modern research universities and the extraordinary and continued rise in publication output (see section 7.2; Powell, Dusdal 2016, 2017a, 2017b in press). Within the global field of science, three geographical centers of scientific productivity have emerged over the twentieth century: Europe, North America, and Asia. Their relative importance fluctuates over time, but today all three centers continue to be the key regions in the production of scientific research in STEM+ journals. Especially in Asia, the growth rates have risen massively in recent years (Powell et al. 2017 in press). Second, I investigated that all countries worldwide invest more into research and development (R&D) (figure 9, p. 140). These investments have a clear impact on the scientific productivity of nations, yet there are important differences between countries in absolute production and productivity rates. Alongside direct investments in R&D or the application of patents in STEM+-fields that influence the expansion of science, the capacity for producing more knowledge fundamentally depends on rising student enrolments, a growing number of researchers, the widening of research activities into various arenas of society, the development of products, and the (re-)foundation of universities (Powell, Baker, Fernandez 2017 in press). As part of the higher education expansion and massification during the 1960s and 70s, the numbers of researchers and students rose tremendously. The growth of scientific publications thus results from the on-going institutionalization of higher education and science systems worldwide. The growth of publications is also explained by the steady growth in the number of researchers working within these growing – and increasingly interconnected – systems. Third, I could reject the argument of Derek J. de Solla Price that the pure exponential growth of scientific literature has to flatten or would slow-down several decades after the advent of “big science” (see paragraph 2.4; figure 4 and 10; p. 53, 147). Although radical historical, political, economical, and technical events (see figure 11, p. 150) led to punctual short-term decreases in publication outputs, the long-term development of universities and other organizational forms producing science led to sustained growth of scientific publications, with the numbers of publications rising unchecked over the long twentieth century. In 2010, the worldwide scientific productivity in leading STEM+ journals was about one million articles annually. Fourth, I could show that the absolute numbers have to be put into perspective and standardized in relation to the investments in R&D, the size of the higher education and science systems, the number of inhabitants (see figure 12, p. 159), and the number of researchers (table 3, p. 162; figure 13, p. 164). The initial expansion of scientific publications in STEM+-fields is based on a general growth of higher education and science systems. The different institutional settings and organizational forms that produce science have an impact on scientific productivity. The selected country case studies – Germany, Great Britain, France, Belgium and Luxembourg – demonstrate that systems with strong research universities are highly productive; they seem to provide conditions necessary for science. As a result, not only the number and quality of researchers is important, but also the institutional and organizational settings in which they are employed. Fifth, in international comparison, Germany continues to contribute significantly to scientific productivity in STEM+ fields. With an annual growth rate of 3.35%, Germany follows the United States and Japan. In 2014, German governments invested €84.5 billion in R&D – 2.9% of overall GDP. The EU-target of 3% by 2020 was barely missed. In 2010, Germany produced 55,009 research articles (see table A5). In comparison to Great Britain, France, Belgium and Luxemburg, Germany still leads in scientific output in Europe –comparing just the absolute numbers. The size of the country itself and the institutionalization of the higher education and science systems influence publication outputs, of course, with these absolute numbers in relation to other key indicators showing a different picture. Standardized by the number of inhabitants, Germany published less articles per capita than Belgium and Great Britain. The number of researchers amounted to 327,997 (FTE) in 2010. The ratio of inhabitants to scientists was 1,000:4. Among these countries studied in-depth, Luxembourg and Great Britain had more researchers per capita than did Germany. The interplay of the organizational forms of science in Germany between 1900 and 2010 On the basis of the analysis of the global and European contexts, and development of worldwide scientific productivity over time in chapter 7, I started the in-depth case study of Germany. Bridging this overview and the following in-depth analyses is a chapter on the institutionalization of the German higher education and science system (see chapter 8). Here, I described the most important institutions and organizations and the organizational field – universities, extra-university research institutes and universities of applied sciences. Furthermore, I discussed the differences between West and East Germany during their division (1945–1990). Summarizing the most important results shows that the development of publications in Germany follows global and European trends (on a lower scale) (see figure 16, p. 208). Over time, Germany experienced pure exponential growth of scientific publications and a rising diversity of organizational forms that contribute to scientific productivity (see sections 9.1 and 9.3). I answered the following three research questions: “how has the scientific productivity in Germany developed between 1900 and 2010”, “among all science producing organizational forms, what do the key organizational forms contribute to scientific productivity”, “which organizational forms provide the best conditions for scientific productivity”, and “which single organizations are the most research intense in Germany”? First, the growth curve of scientific publications in Germany turns out as expected – it shows pure exponential graph, comparable with the worldwide and European development of scientific productivity between 1900 and 2010. Here, too, cataclysmic events such as the two world wars and the Great Depression as well as reunification had only short-term (negative) impact (figure 11, p. 150) on scientific productivity, without even a medium-term slow-down or flattening of the curve. By 2010, the total number of publications in STEM+ fields by researchers in German organizations topped 55,000 in one year alone. Second, a detailed examination and comparison of the development of scientific productivity in West Germany and East Germany between 1950 and 1990 showed that the growth rate of Germany (altogether) was based mainly on steady growth of scientific publications in West Germany (see figure 17, p. 211). The growth curve of the former GDR was quite flat and proceeded on a very low level. As a result, I conclude that the GDR’s higher education and science system, based on its academy model, did not provide conditions for scientific productivity as optimally as did the BRD. Third, a detailed analysis of the “key classical” organizational forms of science – universities and extra-university research institutes – show that universities were and are the main producers of scientific publications in STEM+ from 1975 to 2010 (see figure 18, p. 217). On average, university-based researchers produced 60% of all articles and defended their status against other organizational forms, which leads to the rejection of the Mode 2 hypothesis. Non-university publications reached an average of 40%. But that does not mean that other organizational forms were not producing science as well. The percentage share of articles is ultrastable and shows only marginal variations. The thesis that the proportion of university publications should decrease over time can be rejected for the period from 1975 to 2010. This suggests that scientific productivity of universities is actually rising, since despite decreasing financial support (R&D) in favor of extra-university research institutes, the universities produced more research articles with less resources over time. Fourth, although not only scientists within universities and research institutes publish their research in scientific journals, jointly these organizational forms have produced more than three-quarters of all research articles since 1980. Already in the earlier years, they produced a large number of scientific articles. Other organizational forms also generate scientific knowledge (for an extensive description of the organizational form matrix, see table 4, pp. 222f.). Especially scientists in firms, government agencies, and hospitals publish articles in peer-reviewed journals in STEM+ (see figures 19 and 20; pp. 220, 246). Indeed, the universities have been the driving force of scientific productivity for more than a century. With their specific orientation to basic research and their linkage of research and teaching, they provide conditions that facilitate the production of science. Universities are among the oldest institutions with a high degree of institutionalization. All other organizational forms (academies, associations, infrastructures, laboratories, military, museums and non-university education) were identified in the dataset played only a minor role and were summarized in the category “further types”. Fifth, the analysis of the ten most research-intensive single organizations in Germany in the year 2010 confirmed the results. Only universities and institutes were part of this group. A summary of publications of single institutes under their umbrella organizations shows that the institutes of the Max Planck Society and of the Helmholtz Association are the leading science producers in Germany, outpacing the scientific productivity of universities, but only when aggregating the contributions of dozens of individual institutes (see table 5, p. 259f). An analysis of single institutes shows that these research institutes cannot compete with universities, because of their size and the number of researchers. The Charite – Universitätsmedizin Berlin, a hybrid organization, is another leading science producer in Germany. National and international cooperation of scientific research Finally, increasing internationalization of research has impacted on national and international cooperation. leading to collaboratively-written publications in scientific journals. Through advancing globalization, national and international scientific cooperation increased in volume and importance. International cooperation in STEM+ is facilitated by the reputation of the research organization and of the co-authors, higher visibility within the scientific community and more possibilities for interdisciplinary research as well as better or more specialized facilities. Today, more than a third of all research articles worldwide are produced in scientific collaboration; only around a quarter are single-authored articles. In contrast to Humboldt’s principle “in Einsamkeit und Freiheit” (in loneliness and freedom), research is no longer done by one scientist, but is much more likely the result of collaboration. Research networks are increasingly important, and researchers share their common interests on a research question, publishing their results in joint publications. Researchers, organizations, and indeed countries differ in the ways they organize their research and thus how they enable research and collaboration. This depends on location, size, higher education and science system, the organizational field and organizations. Here, varying patterns of scientific cooperation were presented, showing a massive increase in scientific collaboration in (inter)national co-authorships over time. Until the 1990s, researchers in all investigated countries (France, Germany, Great Britain, USA, Japan, China, Belgium, Luxembourg) published their research articles mainly as single-authored papers. Only since the 1990s have co- and multi-authored publications risen (considerably): In 2000, only a third of all publications were published by one author. In 2010, the proportion reached its lowest level with only one-fifth of all papers single-authored (see table 6, pp. 279f). Countries differ considerably in their amount of collaboratively-written research articles. References Powell, J. J. W. & Dusdal, J. (2016). Europe’s Center of Science: Science Productivity in Belgium, France, Germany, and Luxembourg. EuropeNow, 1(1). http://www.europenowjournal.org/2016/11/30/europes-center-of-science-science-productivity-in-belgium-france-germany-and-luxembourg/. Last access: 13.12.2016. Powell, J. J. W. & Dusdal, J. (2017a): Measuring Research Organizations’ Contributions to Science Productivity in Science, Technology, Engineering and Math in Germany, France, Belgium, and Luxembourg. Minerva, (). Online first. DOI: 10.1007/s11024-017-9327-z. Powell, J. J. W. & Dusdal, J. (2017b in press). The European Center of Science Productivity: Research Universities and Institutes in France, Germany, and the United Kingdom. IN Powell, J. J. W., Baker, D. P. & Fernandez, F. (Hg.) The Century of Science: The Worldwide Triumph of the Research University, International Perspectives on Education and Society Series. Bingley, UK, Emerald Publishing. Powell, J. J. W., Baker, D. P. & Fernandez, F. (2017 in press). The Century of Science: The Worldwide Triumph of the Research University, International Perspectives on Education and Society Series. Bingley, UK, Emerald Publishing. Powell, J. J. W., Fernandez, F., Crist, J. T., Dusdal, J., Zhang, L. & Baker, D. P. (2017 in press). The Worldwide Triumph of the Research University and Globalizing Science. IN Powell, J. W., Baker, D. P. & Fernandez, F. (Hg.) The Century of Science: The Worldwide Triumph of the Research University, International Perspectives on Education and Society Series. Bingley, UK, Emerald Publishing. [less ▲]

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See detailRational Architecture: Reasoning about Enterprise Dynamics
van Zee, Marc UL

Postdoctoral thesis (2017)

Detailed reference viewed: 22 (9 UL)
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See detailOptinization of wireless energy transfer for mid-range distances
Ripp, Pascal UL

Doctoral thesis (2017)

This thesis deals with the optimization of resonators for wireless power transfer by resonant magnetic coupling, where loosely coupled LC resonators are used for wireless power transmission. While systems ... [more ▼]

This thesis deals with the optimization of resonators for wireless power transfer by resonant magnetic coupling, where loosely coupled LC resonators are used for wireless power transmission. While systems that are currently available use discrete capacitors for frequency tuning, this work proposes self-resonating coils on a printed circuit board. For these coils, different three-dimensional (3D) Computer Aided Design (CAD) models are created and investigated using the method of finite elements. Finally, a set of inductively coupled and capacitively coupled self-resonant coils for the 6.78 MHz ISM band is found. Furthermore, the shielding of the coils with ferrite materials is discussed to maintain a high efficiency for any application. For both types, equivalent circuit models are derived and analyzed. Besides the coil optimization, a power amplifier is also proposed. During operation the optimal operational frequency is maintained by frequency tracking. The theoretical results are verified using a demonstrator circuit. [less ▲]

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See detailDRYING AND CONVERSION ANALYSIS OF BIOMASS BY A DEM-CFD COUPLING APPROACH
Mohseni, Seyedmohammad UL

Doctoral thesis (2017)

Biomass materials as a type of renewable energy sources have attracted many attention nowadays to decrease fossil fuel usage due to ecological and economical benefits. The main objective of this PhD ... [more ▼]

Biomass materials as a type of renewable energy sources have attracted many attention nowadays to decrease fossil fuel usage due to ecological and economical benefits. The main objective of this PhD thesis is studying the drying and conversion of biomass materials with employing a hybrid four-way DEM-CFD coupling approach in which considers the solid particulates as discrete elements coupled via heat, mass and momentum transfer to the surrounding gas as continuous phase. Where a comprehensive three-dimensional numerical model is developed and applied to investigate the complex phenomena taking place during biomass drying and conversion in a reactor. That is referred to take into account the physical and chemical processes as heat-up, drying, pyrolysis, gasification and combustion including the essential heterogeneous and homogeneous reactions which is considered as an interactive solid-gas multiphase system. In the proposed model, the motion and thermodynamic state of the particles are involved with employing the relevant governing equations. Where the conductive and radiative heat transfer between particles as well as convective heat transfer between particles and gas phase are taken into account. In addition, some interfaces are extended for coupling the solid particles and the gas phase to consider the interactions in between. At first, the importance of biomass resources is discussed and then the mathematical modeling employed in the PhD thesis is explained thoroughly. To apply the model, four different cases are assessed where two chapters discuss the drying behavior of biomass particles in two different situations. Afterwards, the motion of solid particles in a bubbling fluidized bed is examined. Finally, the conversion of wood materials in a bubbling fluidized bed is determined. [less ▲]

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See detailDynamic change of the human gastrointestinal microbiome in relation to mucosal barrier effects during chemotherapy and immune ablative intervention
Kaysen, Anne UL

Doctoral thesis (2017)

Numerous studies have demonstrated that the gastrointestinal tract (GIT) microbiota plays important roles for the human host. Since the GIT microbiota interfaces with the immune system and represents a ... [more ▼]

Numerous studies have demonstrated that the gastrointestinal tract (GIT) microbiota plays important roles for the human host. Since the GIT microbiota interfaces with the immune system and represents a first line of defense against infectious agents, interest has grown in whether the GIT microbiota may influence the outcome of different anticancer treatments. In this study, the GIT of pediatric patients with different cancer types as well as adult patients with hematologic malignancies undergoing an allogeneic hematopoietic stem cell transplantation were sampled throughout their treatment. In order to deeply profile not only the composition of the community, but also the functional capacity and expression, recently developed wet- and dry-lab methodologies for integrated multi-omic analyses were applied. The trajectories of the prokaryotic and microeukaryotic GIT communities of the patients were described in detail using 16S, 18S rRNA gene amplicon sequencing, as well as metagenomic and metatranscriptomic shotgun sequencing. Indeed, changes in the GIT microbiome in response to treatment were detected. Some changes that are generally thought to be detrimental for human health were detected during treatment, such as a decrease in alpha-diversity, a decrease in relative abundance of bacteria associated with health-promoting properties (such as Blautia spp., Roseburia spp. and Faecalibacterium spp.), as well as an increase in the relative abundance of antibiotic resistance genes. These changes were more pronounced in the adult hematology patients than in the pediatric patients, which is likely due to the more intensive treatment. Some observations need further investigation in order to explain their implication in human health. For example, in the pediatric patients, lower relative abundance of Akkermansia muciniphila was associated with mucositis and functional gene categories that are linked to bacteriophages or the bacterial defense mechanism against bacteriophages were associated with the overall status of the patient and mucositis development. Importantly, in both cohorts, high inter-individual but also high intra-individual variation in the prokaryotic communities were detected while the microeukaryotic community did not exhibit drastic changes. In conclusion, the employed integrated multi-omics analysis allowed detailed profiling of the GIT community including archaea, bacteria, eukaryotes and viruses as well as the functional potential including antibiotic resistance genes. In the future, analysis of the individual-specific processes within the GIT microbial community of patients throughout treatment might allow to adjust therapy regimens accordingly and improve the overall outcome of the therapy. [less ▲]

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See detailWhat Dignity Demands: From Political to Poetical Liberalism
Mailey, Richard Samuel David UL

Doctoral thesis (2017)

The thesis attempts to measure the disjoint between the promise of human dignity that appears at the heart of Western law (e.g. in national constitutions and international human rights instruments), and ... [more ▼]

The thesis attempts to measure the disjoint between the promise of human dignity that appears at the heart of Western law (e.g. in national constitutions and international human rights instruments), and the experiences of exclusion and frustration that, in 2017, have seen many Westerners turn to anti-liberal, populist demagogues for relief. In measuring this disjoint, the thesis looks to the work of liberal and anti-liberal theorists alike, including John Rawls, Bruce Ackerman, Carl Schmitt and Jacques Derrida. It then uses the insights gained to construct a liberal theory that can overcome the key problems identified, before using this theory to critically engage with the constitutional jurisprudence of three very different states: Canada, South Africa and the United States. [less ▲]

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See detailSpin texture of two-dimensional topological insulators
Rod, Alexia Nibal UL

Doctoral thesis (2017)

Since the discovery of two-dimensional topological insulators a decade ago, their one-dimensional edge states have attracted significant attention due to their unique properties. For example due to time ... [more ▼]

Since the discovery of two-dimensional topological insulators a decade ago, their one-dimensional edge states have attracted significant attention due to their unique properties. For example due to time-reversal symmetry, they are protected against elastic backscattering and they propagate such that electrons with opposite spins move in opposite directions. In fact, the only necessary symmetry to sustain the edge states is time-reversal symmetry. Moreover in experimental setups, the axial spin symmetry seems to be absent. This absence allows new processes to appear such as inelastic backscattering. However, these consequences were neglected in most theoretical works where the spins are considered to be polarized in the z direction. The aim of this thesis is to provide a more realistic model taking into account a broken axial spin symmetry. In this scheme, we show that a rotation of the spin quantization axis as a function of momentum always appears. This observation leads us to develop a deeper understanding of the size of the rotation related to the material parameters and material models, using also realistic values. It also leads us to understand the implications in real space in cases where translation invariance is lost and how to quantify the rotation in such systems. The new processes which arise when the axial spin symmetry is broken have important consequences for transport in real materials. To see this, we consider a Hall bar with a hole in its middle, i.e. an antidot. This enables us to create two tunneling regions in order to probe the effect of this generic model. We also consider the effect of Coulomb interactions around the hole, as they can be important in such geometry. We discover that it is possible to probe directly the absence of axial spin symmetry. As experimental evidence is important to investigate our theoretical findings, we propose spectroscopic means to probe the spin texture. Finally, we also consider one of the experimentally-known candidate materials, namely InAs/GaSb heterostructures. From the k.p Hamiltonian, it is possible to show that their bandstructure shows some anisotropies. The latter is also reflected in the spin texture of their edge states. [less ▲]

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See detailInvestigation of the Nuclear Function of Tes, an Actin-Binding LIM Protein and Potential Tumor Suppressor
Vaccaroli, Raffaella UL

Doctoral thesis (2017)

The nucleus and the actin cytoskeleton are two distinct components of the eukaryotic cell. While the actin cytoskeleton is a dynamic structure that confers a high degree of cellular mobility as well as a ... [more ▼]

The nucleus and the actin cytoskeleton are two distinct components of the eukaryotic cell. While the actin cytoskeleton is a dynamic structure that confers a high degree of cellular mobility as well as a connection to the extracellular environment, the nucleus contains the genome and is strongly associated with gene expression from the steps of signal transduction to the actual transcription and the resulting translation. Although both components were initially studied separately, the ever-growing knowledge has lately asserted that they are tightly connected. In line, multitude of actin binding proteins were found to have roles in the nucleus, in addition to their well described roles in the cytoplasm. This research work focuses on the actin cytoskeleton protein Tes and its role in the nucleus. Tes is considered as a tumor suppressor protein, since its expression is reduced in different types of cancer cell lines and primary tumors, while its re-expression inhibits various aspects of cancer progression such as invasiveness and metastasis. As a cytoskeletal protein, Tes has been associated with actin polymerization as well as with cell migration and cell spreading. Our results show that, in addition to its cytoplasmic localization, Tes is localized in the nucleus. Artificial size increase of Tes, using a tag based on multiple GFP proteins, allowed us to assign Tes nuclear import to an active mechanism. Through fluorescence microscopy analysis of different modular fragments of Tes, we demonstrated that its PET and LIM1/2 domains are required for its nuclear localization. We also identified a classical monopartite nuclear localization signal (NLS) harbored within its PET domain, required for Tes import in the nucleus. In addition to Tes nuclear import, we also examined its nuclear export. Using the drug Leptomycin B, we demonstrated that Tes nuclear export is active and dependent on the CRM1-export mechanism. By combining protein sequence analysis with point mutations, we identified and characterized the nuclear export signal (NES) at the N-terminus of Tes. Using a photoconvertible probe, we demonstrated the presence of a slower photoconverted fraction of Tes in the nucleus, compared to the more dynamic cytoplasmic fraction. This prompted us to investigate further the existence of potential nuclear partners of Tes. Quantitative mass spectrometry analysis provided evidence for a potential involvement of Tes in nuclear pathways mediating the remodeling of actin, thus suggesting a novel role for Tes in the reorganization of the nuclear actin cytoskeleton. Furthermore, the proteomics studies associated the nuclear localization of Tes with signaling pathways promoting inflammation and cellular death. These results raised the hypothesis that Tes might promote tumor suppression not only through its cytoplasmic functions, but also through these newly described pathways connected to its nuclear localization. Further investigation will be necessary to fully elucidate the function of Tes in the nuclear compartment. [less ▲]

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See detailCross-border evidence gathering: equality of arms within the EU?
van Wijk, Marloes Chantal UL

Doctoral thesis (2017)

The European Union (EU) has set the objective to develop an Area of Freedom, Security and Justice, in which on the one hand freedom of movement is promoted and on the other hand a high level of security ... [more ▼]

The European Union (EU) has set the objective to develop an Area of Freedom, Security and Justice, in which on the one hand freedom of movement is promoted and on the other hand a high level of security is ensured. The EU is therefore adopting measures to enhance international cooperation in criminal matters among the police and judicial authorities of its Member States. The adopted instruments concerning evidentiary matters, such as the gathering, freezing and/or confiscation of information and materials in another EU Member State, seem to serve the main purpose of assisting the authorities in investigating and prosecuting (cross-border) crime. This raises the question to what extent the defence is also given the possibility to gather – or to have gathered – information and materials in another EU Member State with the aim of preparing and presenting its case at trial and, in particular, whether the current (EU) legal framework on cross-border evidence gathering meets the requirements of the principle of equality of arms. This thesis addresses this question by, first of all, discussing the concept of equality of arms, as enshrined in both Article 6 ECHR and Article 47 CFR. It explains to what extent this principle is applicable to cross-border or transnational criminal proceedings and whether it has an autonomous meaning within the EU. In addition, it discusses which requirements can be deduced from the principle in relation to the possibilities of the defence to gather evidence in another EU Member State to prepare and presents its case. Subsequently, the focus is on the development of the European legislation – from both the Council of Europe and the EU – regulating the procedure of cross-border evidence gathering over the last decades. The aim is to explain the position of the defence in this development and to what extent the European legislation gives opportunities to the defence to request the assistance of foreign authorities in obtaining specific information and materials in another EU Member State. In order to understand how the European legislation is applied in practice by the EU Member States, this thesis includes a comparative study of three national jurisdictions: the Netherlands, England and Wales, and Italy. These three jurisdictions each represent a different criminal justice system, either more inquisitorial or adversarial in nature. The comparative study describes how a chosen jurisdiction interprets the principle of equality of arms. Furthermore, it examines to what extent the national jurisdiction allows the defence to carry out independent investigations abroad and how it gives the defence the opportunity to trigger the mechanism of international cooperation and to participate in the requested investigation. Finally, this thesis also includes an analysis of the criminal justice system of the International Criminal Court. In this system evidence gathering depends most of the time on State cooperation and both the Prosecutor and the defence are allowed to conduct independent investigations and seek the assistance of States. It is therefore used as a source of inspiration for potential changes of the EU legislation on cross-border evidence gathering. [less ▲]

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See detailKrankheitsbewältigung im Kontext einer Krebserkrankung im höheren Lebensalter
Lessing, Juliane Eva Margarethe UL

Doctoral thesis (2017)

The risk to develop cancer increases with age. Due to demographic change and extending life expectancy, the number of older cancer patients continues to grow. Despite this, the group of older cancer ... [more ▼]

The risk to develop cancer increases with age. Due to demographic change and extending life expectancy, the number of older cancer patients continues to grow. Despite this, the group of older cancer patients appears to be underrepresented in psycho-oncological research as well as in care and treatment. The present dissertation focuses on the psycho-social situation of older cancer patients in the Greater Region. Three main topics are studied using different methodological approaches. The first main topic focuses on the general situation of older cancer patients in Luxembourg. A descriptive analysis of epidemiological data from the Direction de la Santé and the International Agency for Research on Cancer shows increasing cancer incidence and mortality rates among older adults in Luxembourg. Comparative analyses using the Luxembourgish data from SHARE wave 5 show similar physical and psychological burden among older cancer patients (n = 44) and older cardiac patients (n = 46), but both patient groups report higher burden than older healthy adults (n = 51). Furthermore, in both patient groups, a percentage of about 22 % reports significant psychological burden. The second main topic focuses on the social context of older cancer patients analysing attitudes as well as emotional and behavioural reactions towards older cancer patients. Two quantitative studies using a 2x2x2 factorial vignette approach present each a brief scenario with varying information about a person´s gender, age (study 1: 30 vs. 74 years; study 2: 38 vs. 83 years) and health status (study 1: healthy vs. skin cancer; study 2: colon cancer vs. myocardial infarction). The two studies survey lay persons as well as health professionals and student health professionals (study 1: N = 683; study 2: N = 328). Both studies find no indicators of negative attitudes and reactions towards older cancer patients. However, study 1 shows more negative attitudes towards skin cancer patients but also higher prosocial emotions and less social distancing compared to healthy adults. In study 2, patients with colon cancer are rated as more thoughtful and less responsible for their disease than cardiac patients. Here, no differences are found in emotional or behavioural reactions. The third main topic focuses on individual experiences and coping processes of older cancer patients. Nine qualitative interviews with male and female cancer patients as well as a comparison group of male cardiac patients (each n = 3) between 64 and 90 years are conducted and analysed using qualitative content analysis. Results show that the diagnosis is perceived as a critical life event, but initial psychological burden decreases after the completion of treatment. Particularly, cognitive coping strategies are reported, above all acceptance and comparative processes. Psychological well-being as well as a sense of stability and continuity are maintained in spite of considerable physical changes and constraints. Practical implications of the findings are discussed. [less ▲]

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See detailIntegration of the analysis of non-functional properties in Model-Driven Engineering for embedded systems
Brau, Guillaume Sylvain Denis UL

Doctoral thesis (2017)

The engineering of embedded systems relies on two complementary activities: modeling on the one hand enables to represent the system, analysis on the other hand makes it possible to evaluate the various ... [more ▼]

The engineering of embedded systems relies on two complementary activities: modeling on the one hand enables to represent the system, analysis on the other hand makes it possible to evaluate the various non-functional properties (for example, temporal properties with the real-time scheduling analysis). This thesis deals with the integration between these models and analyses: how to apply an analysis on a model? How to manage the analysis process? The first part of this thesis presents a comprehensive approach to answer these questions. This approach is based on four application layers: (1) models to represent the system, (2) accessors to extract data from a model, (3) analyses to compute output data and/or properties from input data (4) contracts to represent the analysis interfaces and orchestrate the analysis process. The second part of this thesis deals with the experimentation of this approach with concrete systems coming from the aerospace: a drone, an exploratory robot and a flight management system. We demonstrate that the accessors enable to apply various real-time scheduling analyses on heterogeneous architectural models, for example written with the industry standard AADL (Architecture Analysis and Design Language) or the new time-triggered language CPAL (Cyber-Physical Action Language). In addition, contracts make it possible to automate complex analysis procedures: which analysis can be applied on a given model? Which are the analyses that meet a given goal? Are there analyses to be combined? Are there interferences between analyses? Etc. [less ▲]

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See detailHospice. Lieux et expériences de vieillesses. Bruxelles 1830-1914
Richelle, Sophie Marthe UL

Doctoral thesis (2017)

History of old age and experiences of ageing poeple in those places in Brussels between 1830 and 1914

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See detailEntwicklung eines EDV-basierten Frühwarnsystems für die Blankaalabwanderung an der Mosel
Wendling, David UL

Doctoral thesis (2017)

The eel (Anguilla anguilla L.) is a fish that is mainly found in European waters. The River Moselle is among the bodies of water inhabited by this specimen. During the downstream migration into their ... [more ▼]

The eel (Anguilla anguilla L.) is a fish that is mainly found in European waters. The River Moselle is among the bodies of water inhabited by this specimen. During the downstream migration into their Atlantic spawning ground, silver eels often experience severe to fatal injuries while passing the turbines at the barrages. This annual migration takes place in a relatively narrow timeframe. Therefore, knowing the trigger or beginning of said migration, the mortality rate of the eels could be reduced by a fish-adapted turbine control or comparable protective measures. This thesis introduces an early warning system, which predicts the periods of silver eel emigration by means of certain abiotic factors. On the basis of the information gleaned from different studies and the experience gained from many years of professional fishing, those environmental factors were identified which are connected with the migration of the silver eel. Extensive data analyses were used to substantiate these findings. The water flow, the flow differences and the lunar phase were particularly relevant. Furthermore, the season and the water temperature were taken into account. In view of the different sources of information (experience and expert knowledge, data sets and the findings derived from it), a hybrid structure of the early warning system was realized. After examining different methods from the fields of soft computing and mathematics or statistics, the fuzzy logic (knowledge-based), the case-based reasoning (casebased) and the artificial neural networks (data-based) were selected. With each of these methods, an independent prediction model was designed, tested and optimized. Special characteristics were found during the data analysis and were taken into account by the use of adequate modifiers. The models were tested on the basis of the present data sets for the Moselle. It was shown that it is possible to correctly predict most of the situations with increased catches (suggesting a migration). Threshold values for a migration were defined based on the catches. The same was done for the forecast values. Thus, for the 1963 to 1973 data record, a total of 63% (artificial neural networks), 74% (fuzzy logic), and 83% (case-based reasoning) of the events with increased catches could be detected. Since not every situation with a favorable constellation of abiotic factors also led to a migration or higher catches, a lot of "false" forecasts (up to 50%) were made as well. Good results have also been achieved when using data from recent years and most events were identified. A stand-alone program was developed for the practical application of the prognosis models. This early warning system is a software which contains a user interface for reading data and displaying prognosis values and into which the developed prognosis models are implemented. In addition, recommendations for use were compiled and presented. [less ▲]

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See detailMicroRNA regulation of hypoxia-induced tumorigenicity and metastatic potential of colon tumor-initiating cells
Ullmann, Pit UL

Doctoral thesis (2017)

The initiaton and progression of colorectal cancer (CRC), which is the second most common cause of cancer mortality in Western countries, are driven by a subpopulation of highly tumorigenic cells, known ... [more ▼]

The initiaton and progression of colorectal cancer (CRC), which is the second most common cause of cancer mortality in Western countries, are driven by a subpopulation of highly tumorigenic cells, known as cancer stem cells or tumor-initiating cells (TICs). These self-renewing TICs are, to a large extent, responsible for therapy resistance, cancer recurrence, and metastasis formation. TICs are known to extensively interact with their microenvironment and can be influenced by various extrinsic factors, such as inflammatory signaling or tumor hypoxia. Previous expression profiling studies have shown that microRNAs (miRNAs) are involved in the regulation of CRC inititation and metastatic progression. Moreover, specifc miRNAs have been identified as potential mediators of the cellular response to hypoxia. On the other hand, the molecular mechanisms that link hypoxia, miRNA expression, colon TIC regulation, and CRC progression, remain poorly understood. Thus, the main objectives of this work were to analyze the effects of hypoxia on the miRNA expression of colon TICs and to identify miRNAs that regulate metastasis initiation. In a first phase, we generated and thoroughly characterized different stable TIC-enriched spheroid cultures (SCs), both from CRC cell lines and from primary patient material. Each established SC was thereby shown to display key TIC properties, including substantial plasticity, in vitro and in vivo self-renewal capacity and, most importantly, extensive tumorigenic potential. Moreover, the individual SCs displayed increased chemoresistance capacity, compared to adherent counterpart cultures. Taken together, we could demonstrate that the spheroid system is a suitable model to study colon TICs, thereby laying the methodological foundation for the following subparts of this project. In a second step, we studied the influence of hypoxia on the miRNA expression profile of our established SCs. MiR-210-3p was thereby identified as the miRNA with the strongest response to hypoxia. Importantly, both hypoxic culture conditions and stable overexpression of miR-210 were shown to promote in vitro and in vivo self-renewal capacity of our colon TIC-enriched cultures. Moreover, by promoting lactate production and by repressing mitochondrial respiration, miR-210 was found to trigger the metabolic reprogramming of colon TICs towards a glycolytic and aggressive phenotype. Finally, we studied the role of miRNAs in the context of TIC-driven metastasis formation. By comparing primary tumor- and lymph node metastasis-derived SCs, we were able to identify the miR-371~373 cluster as an important regulator of tumorigenic and metastatic potential. Stable overexpression of the entire miR-371~373 cluster, followed by gene and protein expression analysis, enabled us to uncover the transforming growth factor beta receptor II (TGF-βRII) and the inhibitor of DNA binding 1 (Id1) as miR-371~373 cluster-responsive proteins. Most importantly, different sphere, tumor, and metastasis formation assays revealed that the miR-371~373/TGF-βRII/Id1 signaling axis regulates the self-renewal capacity and metastatic colonization potential of colon TICs. Taken together, our findings emphasize the strong plasticity of colon TICs and clearly illustrate that miRNAs can act as potent modulators of essential TIC properties. Accordingly, we could show that miR-210 and the miR-371~373 cluster are involved in metabolic reprogramming of TICs and in the regulation of metastasis formation, respectively. Altogether, our study contributes to a better understanding of the molecular mechanisms that drive TIC-induced tumor progression and may provide indications for interesting miRNA biomarker candidates and target molecules for future TIC-specific therapies. [less ▲]

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See detailScarring effects across the life course and the transition to retirement
Ponomarenko, Valentina UL

Doctoral thesis (2017)

This thesis investigates the long-term negative effects of unemployment, labour market inactivity and atypical employment. Within the theoretical framework of cumulative advantages and disadvantages, it ... [more ▼]

This thesis investigates the long-term negative effects of unemployment, labour market inactivity and atypical employment. Within the theoretical framework of cumulative advantages and disadvantages, it is outlined how life-course differentiation creates gaps between age peers and cohorts and how this leads to social inequality in old age. In the three separate, but linked studies, disadvantages across the career and their associations to retirement are analysed. The focus of the analyses is laid on the outcomes of career disadvantages in form of subjective and financial well-being. The three studies all use the Survey of Health, Ageing and Retirement in Europe. This large and multidimensional panel study provides not only prospective, but also retrospective data on European countries. The data base is employed in different combinations in the studies. In the first and second study, the retrospective wave SHARELIFE provides information on employment biography and is related to well-being indicators of the regular waves. In the third study, the persistence of disadvantages upon retirement is observed with a causal model. The first study investigates how disadvantages are affecting careers and subjective well-being of older Europeans. In two complementary analyses, first the employment history of older Europeans is studied with sequence analysis methods to show how non-employment and part-time work shape careers and to illustrate gender differences. In a second step, indicators of timing and duration, exemplifying the accumulation mechanisms, are related to subjective well-being in old age. The results indicate that women experience more turbulent careers with more periods of non-employment and part-time employment. However, this is not reflected in lower subjective well-being in old age. Accumulation of non-employment disadvantages is far more comprehensive for men than for women. Part-time employment has an ambiguous effect for women, but is not relevant for men. In the second study, the household level is added and it is analysed how an adverse employment history is related to wealth accumulation. The results show that cumulative non-employment and employment in lower occupations has significant disadvantages for wealth accumulation in old age. However, large differences for men and women remain. Particularly, the household composition and household factors are decisive in the effectuality of these disadvantages. The third study includes the scarring question, that means if career disadvantages continue beyond the working life. The study examines whether non-employment disadvantages are still found in retirement and the extent to which well-being levels change in the transition to retirement. Well-being scores before and after retirement are obtained and unbiased effects of the retirement transition are identified. Results indicate that being unemployed before retirement is associated with an increase in life satisfaction, but presents mainly a catching-up effect compared to employed persons transitioning to retirement. Findings are robust to selection into unemployment and country differences. [less ▲]

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See detailThe spread of public-private partnerships: a political economy analysis
Liebe, Moritz UL

Doctoral thesis (2017)

Amid a general trend to redefine and reform public services, public authorities around the globe have introduced and experimented with innovative ways of involving private actors in the provision of ... [more ▼]

Amid a general trend to redefine and reform public services, public authorities around the globe have introduced and experimented with innovative ways of involving private actors in the provision of public infrastructure and services — often referred to as Public-Private Partnerships (PPPs). Infrastructure-related PPPs are, usually, a contractual arrangement for a single undertaking to build and refurbish an asset where the public authority would mandate a single company to arrange the financing of the endeavour, to design and build the project, to be in charge of the maintenance and even, on some occasions, to manage the operation of public services related to the asset. A number of European national and regional governments and the European Union institutions have showed great interest in PPPs as an alternative procurement method, whereas some governments have abstained from this trend entirely or only used PPPs sporadically. This thesis — operationalised by a mix of qualitative and quantitative methods — is an inquiry into what factors inform the decision of public authorities to engage with PPPs more frequently. It involves testing a number of specific hypotheses generated to explain differential national engagement with PPPs, notably: the efficiency and effectiveness of the state (expressed as the state of public finances and the performance of public services); and a number of institutional variables — with institutions understood in this context as the incentives and constraints imposed by the national political system and the dominant mode of capitalism. This study reconfirms findings from the PPP literature on the conditions under which public authorities are more likely to have recourse to PPPs — i.e., authorities with less than optimally performing public services and/or experiencing budgetary constraints are expected to use PPPs more frequently. This thesis, however, also argues that other institutional factors are equally important for the likelihood of countries using this alternative procurement and financing method. On the one hand, the findings suggest that the ability of governments to introduce reforms — in the form of a favourable veto point structure in the political system and the government’s relative power vis-à-vis opposition parties — is a significant predictor for the numbers of established PPPs. On the other hand, the analysis shows the relevance of the economic system; the analysis reveals that the traditional mode of coordination in the national economy — i.e., either through contracts or non-market relations — has a greater influence on PPP uptake than commonly discussed in the literature. [less ▲]

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See detailNew models to study the cross-talk between the protein repair L-isoaspartyl methyltransferase and cell signalling
Soliman, Remon UL

Doctoral thesis (2017)

Isomerization of L-aspartyl and L-asparaginyl residues to form L-isoaspartyl residues in proteins is one type of protein damage that can occur under physiological conditions and can potentially lead to ... [more ▼]

Isomerization of L-aspartyl and L-asparaginyl residues to form L-isoaspartyl residues in proteins is one type of protein damage that can occur under physiological conditions and can potentially lead to conformational change, loss of function and enhanced protein degradation. Protein L-isoaspartyl methyltransferase (PCMT or PIMT) is a repair enzyme, which allows the reconversion of L-isoaspartyl residues to L-aspartyl residues in protein. Although the catalytic function of PCMT is known, its physiological roles remain less well understood. Pcmt1 gene knockout in mice leads for example, via molecular mechanisms that remain mostly obscure, to activation of insulin/IGF-1 and MAPK signalling pathways in the brain, and premature death due to massive epileptic seizure events. In this doctoral research project, we have used both mammalian cells and zebrafish models to investigate the impact of PCMT deficiency on insulin/IGF-1, MAPK and calcium signalling as well as how PCMT may be involved in epilepsy. In mammalian cells we used shRNA and CRISPR/Cas9 technology to reduce or completely silence PCMT expression, with the main objective being to mimic, in cell culture, the activation of the IGF-1 and MAPK signalling pathways observed in Pcmt1 knockout mice in the hope to thereby increase the chances to elucidate the underlying molecular mechanisms. In zebrafish we used an antisense morpholino-based strategy to knock down both PCMT homologs and thereby establish a new whole organism model to further study the physiological functions of PCMT, more particularly in the brain. Our results indicate that insulin/IGF-1 signalling is not affected by PCMT knockdown or knockout in mammalian cells whereas a time-dependent MAPK pathway activation could be detected in a Pcmt1 knockout mouse hippocampal cell line. In zebrafish, we showed that the two PCMT homologs Pcmt and Pcmtl (Pcmt/l) possess isoaspartyl methyltransferase activity. In pcmt/l knockdown (or morphant) zebrafish larvae we did not detect abnormal electrical activity in the brain, but we identified movement impairment and strongly perturbed brain calcium fluxes. Abnormal calcium responses were also observed in the Pcmt1 knockout mouse hippocampal cell line. We concluded that the interplay between PCMT and growth signalling pathways is highly dependent on experimental model and may not be amenable to investigation in cell culture. Importantly, our results clearly show that PCMT plays a pivotal role in calcium signalling and suggest that PCMT-dependent repair mechanisms may be important to prevent calcium-related neurological disorders. [less ▲]

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See detailStudy of Metabolite Repair in Eukaryotic Cells: Metabolic origin and fate of D-2-hydroxyglutarate in yeast and effect of NAD(P)HX repair deficiency on yeast and human cells
Becker-Kettern, Julia UL

Doctoral thesis (2017)

Abnormal metabolites, which are useless and can even be toxic, are constantly generated inside the cell by unwanted chemical reactions or by enzymatic side reactions. Metabolite repair enzymes clean the ... [more ▼]

Abnormal metabolites, which are useless and can even be toxic, are constantly generated inside the cell by unwanted chemical reactions or by enzymatic side reactions. Metabolite repair enzymes clean the metabolite pool from these molecules. The proportion of proteins annotated as metabolite repair enzymes is currently very small but accumulating evidence suggests that a bigger part might be hidden among proteins of unknown function. The aim of this thesis was to study two of these metabolite repair systems and their physiological relevance in more detail as their importance is well illustrated through implication in disease processes. D-2-hydroxyglutaric aciduria, a severe human neurometabolic disorder, can be caused by a deficiency in the metabolite repair enzyme D-2-hydroxyglutarate (D-2HG) dehydrogenase. Higher levels of D-2HG have also been observed in cancerous cells with a mutated form of isocitrate dehydrogenase. Strikingly, in the model organism Saccharomyces cerevisiae, 2-hydroxyglutarate metabolism had remained completely unexplored. We elucidated the metabolic pathways involved in D-2HG formation and degradation in yeast using bioinformatics, metabolomics, yeast genetics, and classical biochemical tools. We discovered that Dld3, currently annotated as a D-lactate dehydrogenase, actually degrades D-2HG to α-ketoglutarate while reducing pyruvate to D-lactate, thereby acting as a transhydrogenase. We also demonstrated that the yeast phosphoglycerate dehydrogenases Ser3 and Ser33 are major sources for D-2HG formation. These findings paved the way to integrate 2HG and its associated genes into the yeast metabolic network and might help, on the long-term, to better understand underlying mechanisms in human disease as well. Other recently identified metabolite repair enzymes, NAD(P)HX dehydratase and NAD(P)HX epimerase (encoded in yeast by the YKL151C and YNL200C genes, respectively), specifically act on NADHX and NADPHX, hydrated and inactive forms of the central NADH and NADPH cofactors. Although extensively biochemically characterized, the physiological importance of these two enzymes still remains largely unclear. Only very recently, case reports were published indicating a correlation between NAD(P)HX repair deficiency and severe neuropathological symptoms starting in early childhood upon events of febrile illnesses and rapidly leading to a fatal outcome. We systematically analyzed extracts of NAD(P)HX repair deficient yeast and human cells using HPLC and LC-MS/MS methods. This enabled us to demonstrate that NADHX and NADPHX can be formed intracellularly. In the yeast system, NADHX accumulation, which could be modulated by the cultivation temperature, was accompanied by a decrease in intracellular NAD+ levels. Furthermore, we showed that NADHX interferes with serine metabolism by inhibiting the first step of the main synthesis pathway of this amino acid. In the human cell system, NAD(P)HX dehydratase deficiency led, as in yeast, to intracellular NADHX accumulation, but also to a marked decrease in cell viability after prolonged cultivation times. This is, to our knowledge, the first report about the effect of NADHX accumulation on cellular metabolism. Expanding our experimental strategy of combined transcriptomics and metabolomics approaches to the human cell model might ultimately lead to the discovery of the disease-causing cellular process. The findings in both projects led to an unexpected connection between NAD(P)HX and 2HG metabolism via the yeast homologues of 3-phoshpoglycerate dehydrogenase, Ser3 and Ser33. Both proteins catalyze the oxidation of 3-phosphoglycerate to 3-phosphohydroxypyruvate in the initial step of de novo serine biosynthesis with a concomitant reduction of α-ketoglutarate to D-2-hydroxyglutarate. By acting as transhydrogenases, they substantially, even though not exclusively, contribute to D-2HG formation in yeast. The very same enzymes were strongly inhibited in vitro and, as suggested by our findings, also in vivo by the presence of NADHX, leading to serine depletion in NAD(P)HX repair deficient cells. [less ▲]

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