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See detailFinancial modeling with Volterra Lévy processes and applications to option pricing, interest rates and credit risk modeling
Elrahouli, Sami Abdul Latif UL

Doctoral thesis (2014)

Abstract. This work investigates financial models for option pricing, interest rates and credit risk with stochastic processes that have memory and discontinuities. These models are formulated in terms of ... [more ▼]

Abstract. This work investigates financial models for option pricing, interest rates and credit risk with stochastic processes that have memory and discontinuities. These models are formulated in terms of the fractional Brownian motion, the fractional or filtered Lévy process (also doubly stochastic) and their approximations by semimartingales. Their stochastic calculus is treated in the sense of Malliavin and Itô formulas are derived. We characterize the risk-neutral probability measures in terms of these processes for options pricing models of Black-Scholes type with jumps. We also study interest rates models, in particular the models of Vasicek, Cox-Ingersoll-Ross and Heath-Jarrow-Morton. Finally we study credit risk models. [less ▲]

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See detailLuxembourg and Europe: The Europeanization of National Officials
Hielscher, Kathleen UL

Doctoral thesis (2014)

This study provides a systematic account of European adaptation (Europeanization) of the national core executive in Luxembourg. So far the existing literature on European adaptation processes regarding ... [more ▼]

This study provides a systematic account of European adaptation (Europeanization) of the national core executive in Luxembourg. So far the existing literature on European adaptation processes regarding national officials and their administrative structures does not address the case of Luxembourg nor does it link the analysis of European adaptation of actors and institutions in one research design. The analytical framework used in order to unveil Europeanization processes in the case of Luxembourg encompasses a mixed-method approach using quantitative but mostly qualitative techniques. The discovery of the way Luxembourg manages the coordination of its EU policy and the extent to which the core executive has been affected by the European socialization process provides evidence of successful European adaptation of the Luxembourgish core executive to the EU. Displaying a coordination system of EU policy that is structured by informal procedures, the flexibility and pro-integrationist outlook of national civil servants is mainly responsible for Luxembourg’s efficient management of EU affairs. Despite being one of the smallest member states in the EU, Luxembourg has created a coordination system for EU policy that ensures successful management of its work in the European arena. While uncovering institutional and individual adaptation processes in Luxembourg, this thesis is the first systematic account that integrates socialization and coordination issues together into the Europeanization research agenda. [less ▲]

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See detailLes circulations internationales en Europe au XXIème siècle. De l’étude des répartitions monétaires à la modélisation d’un système complexe.
Le Texier, Marion UL

Doctoral thesis (2014)

Over the last century, the circulation of money has been used by historians as an indicator of the relationships between people across space and time. The introduction of a single currency, the euro, on ... [more ▼]

Over the last century, the circulation of money has been used by historians as an indicator of the relationships between people across space and time. The introduction of a single currency, the euro, on January 1, 2002 in 12 European countries offers the opportunity to trace the paths of international mobility in that part of the world. This thesis aims to provide an account of the relations - specific and banal - established between European territories from the analyses of the complex shapes formed by the monetary distribution. The approach is based on the design of a conceptual model formalising the internationalisation of flows exchanged between places in a specified time period. The intensity, diversity and scope of monetary circulation are then matched to diverse forms of international mobility through empirical modelling. This hypothetico-deductive approach is based on the study of more than 20,000 money-bags surveyed in France between June 2002 and December 2011. A case study on Luxembourg allows for observing these traces of international mobility at a finer spatial scale. These analyses reveal a series of factors influencing the spread of foreign coins that fall into three categories: spatio-temporal, territorial and social effects. Finally, an individual-based simulation model is built to study the possible interactions between the different factors in a dynamic and multilevel framework. The thesis concludes that the analysis of money circulation is an accurate way to understand, analyse and differentiate the patterns of international mobility in Europe at different scales. [less ▲]

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See detailPhotoluminescence and solar cell studies of chalcopyrites - comparison of Cu-rich vs. Cu-poor and polycrystalline vs. epitaxial material
Regesch, David UL

Doctoral thesis (2014)

The quasi-Fermi level splitting (qFls) in a solar cell absorber limits the maximum achievable open circuit voltage of the final device. A calibrated photoluminescence set-up allows the determination of ... [more ▼]

The quasi-Fermi level splitting (qFls) in a solar cell absorber limits the maximum achievable open circuit voltage of the final device. A calibrated photoluminescence set-up allows the determination of the qFls at room temperature under conditions equivalent to the illumination from the sun. In this work the qFls is used as an indicator for the quality of epitaxial and polycrystalline thin CuInSe2 films with different compositions. It is shown, that the epitaxial material exhibits improved optoelectronic quality noticeable in the higher qFls (50-100meV) when compared to the polycrystalline counterpart. Furthermore, a dependency on the Cu/In ratio is noticed: In Cu poor material (Cu/In<1) the qFls increases with an increasing Cu concentration and levels off for the absorbers grown under Cu-rich conditions (Cu/In>1). The difference between absorbers grown under Cu-poor and Cu-rich conditions is found to be in the order of 150meV. Additionally, the compositional dependence of the Urbach energy and of the band gap energy has been evaluated from the PL spectra at room temperature. Slightly higher bandgaps and lower Urbach energies have been found for the Cu rich material compared to the Cu poor absorbers. The time dependent change of the qFls of bare CuInSe2 absorbers exposed to air is presented and shows for Cu-poor absorbers a pronounced and for Cu-rich material a slower degradation. It is shown, that a chemical etching in potassium cyanide refreshes the degraded material to an extent comparable to freshly grown samples, and that the deposition of a CdS buffer layer passivates the surface. Epitaxial Cu(In,Ga)Se2 is grown by means of metal organic vapour phase epitaxy and used to produce epitaxial solar cells. A maximum power conversion efficiency of 6.7% has been achieved. All solar cells suffer from dominant interface recombination processes which limit the device performance. The critical interface is between the absorber layer and the CdS buffer and related to the high gallium content. [less ▲]

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See detailINFLUENCE OF 1,25-DIHYDROXYVITAMIN D3 ON MONOCYTIC THP-1 CELLS IN A TNF-ALPHA-INDUCED INFLAMMATORY STATE: A COMBINED EXPERIMENTAL AND SYSTEMS BIOLOGY APPROACH
Kätzel, Thorben UL

Doctoral thesis (2014)

The focus of this thesis is the understanding of the molecular mechanisms related to the recently discovered anti-inflammatory function of vitamin D and its ability to suppress tumor growth and chronic ... [more ▼]

The focus of this thesis is the understanding of the molecular mechanisms related to the recently discovered anti-inflammatory function of vitamin D and its ability to suppress tumor growth and chronic inflammation. Our aim is the analysis of the modulatory effects of 1,25-dihydroxyvitamin D3 (1 ,25(OH)2D3 or 1,25-D3) on gene expression in THP-1 cells in a TNF- alpha-induced inflammatory state. This monocyte cell line was used as a model system for potential monocyte-endothelial interactions. For the gene expression profiling, the cells were treated with TNF-alpha and 1,25-D3 and analysed at three different time points, 1h, 4h and 24h, by using Illumina Human HT-12 v4.0 micro arrays to achieve specific changes in the mRNA expression levels. The validation of the micro array data was performed by RT-qPCR and resulted in gene clusters regulating cellular growth, cell development and cellular movement. Specifically, we were able to identify the genes BCL2, CCL2, MGAT3, NCF1, ORM1 and RAB37 and their expression levels were analysed in the presence and absence of vitamin D and TNF-alpha using quantitative PCR. Furthermore, the expression of the acute phase plasma alpha-globulin glycoprotein alpha-1-acid glycoprotein (AGP) encoded by ORM1 gene, and beta -1,4-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase (Gnt-III) encoded by MGAT3 gene were investigated via quantitative western blot and ELISA experiments after treatment of cells with 1,25-D3 and TNF-alpha , where post-stimulation protein levels evolved correspondingly for the former protein. Subsequent invasion assays showed an inhibitory effect on invasion efficacy of THP-1 cells after knockdown of ORM1 with specific siRNA. Moreover, microarray data and database knowledge were used to generate a network containing previously identified and validated target genes. This candidate network is modeled computationally with a biochemical reaction-based Boolean model. It was further curated by an evolutionary algorithm-based pruning step removing unnecessary nodes and interactions, called MORGEN. This ultimately resulted in a model allowing the qualitative description of the observed gene expression patterns. In conclusion, 1,25-D3 affects a range of genes in THP-1 cells in TNF- alpha-induced-inflammatory state. We showed that it potentially alters transendothelial migration of monocytic cells, among other ways, via increase of AGP expression after exposure of the cells to both 1,25-D3 and TNF- alpha. Furthermore, the generated model could be reduced significantly via implementation of MORGEN. This promises a valuable new tool for network reduction, an essential step for generation of elaborated models with computationally feasible properties that help to understand the complex network and deregulation of signaling networks in different diseases. [less ▲]

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See detailLa capabilité de santé des aidants familiaux: Analyses du paradigme et pistes d'opérationnalisation
Bucki, Barbara UL

Doctoral thesis (2014)

Home care of persons with a chronic disease is increasingly provided by family caregivers, but their lifestyle creates a risk to their health. Therefore, leading a research on their "health capability ... [more ▼]

Home care of persons with a chronic disease is increasingly provided by family caregivers, but their lifestyle creates a risk to their health. Therefore, leading a research on their "health capability", in other words, on their ability to adopt a healthy lifestyle is of major scientific interest. The operationalization of this paradigm, developed by Ruger in 2010 to understand the factors of maintaining a state of optimal health, has been the heart of our research. Based on a quantitative data collection conducted in Luxembourg and Lorraine (France), a Health Capability of Family Caregivers instrument (HCFC-20 items) was developed and tested. It explores eight areas: physical health, psychological health, lifestyle value, sense of self-efficacy, family support, social capital, material conditions/sense of security, satisfaction with information and healthcare services. Additional qualitative surveys have completed the HCFC-20 with 77 items covering areas such as motivation, life skills and coping styles. This instrument allows to develop personalized diagnoses and to evaluate health-promoting programs. Our preliminary analyses have also indicated that the impacts of a chronic disease are experienced jointly in patient-caregiver dyads; and the value placed on the role of caregiver is encouraged by the support from professionals and a social network. In order to improve the health capability of caregivers, taking into account both their autonomy and their need for support is therefore required. [less ▲]

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See detailAnonymous Leader Election in One- and Two-Dimensional Cellular Automata
Banda, Peter UL

Doctoral thesis (2014)

Leader election plays a crucial role in numerous distributed protocols, multi-agent systems and biological societies. Yet there is a fundamental gap in understanding its simplest variant, such as, in ... [more ▼]

Leader election plays a crucial role in numerous distributed protocols, multi-agent systems and biological societies. Yet there is a fundamental gap in understanding its simplest variant, such as, in cellular automata, employing components that are fully uniform, deterministic, and anonymous. In this thesis, we investigate various one- and two-dimensional binary state cellular automata that elect a leader by transforming a random initial configuration to a state where exactly one arbitrary cell is active (leader). A cellular automaton (CA) is a distributed system with a spatial topology where each processor (cell) is locally connected to its neighbors. A transition rule is represented by a look-up table, which is uniform, i.e., shared among all cells. We show that leader election is possible even in the minimal, anonymous, and uniform architecture of a binary CA. Despite being one of the structurally simplest distributed systems, a CA can exhibit various types of behavior, including complex dynamics and self-organization. Our methodology leverages evolution of CAs by employing genetic algorithms, where chromosomes encoding candidate look-up tables undergo selection, cross-over and mutation. Even though CA's transition rules are just local and uniform, the leader election task is global and requires coordination of all cells. The findings show that the emergent dynamics of the best binary CAs are characterized by sophisticated coordination and global computation of cells, a product of spatio-temporal structures or events, namely regular domains, particles and particle interactions, known from the theory of computational mechanics. This collision-based computing enables CA to carry and exchange information over distances, eventually eliminating all but one candidate for leader. In two dimensions, slowly-contracting regions connected by lines of active cells propagate throughout the lattice and sweep any remaining active cells, before shrinking to a single cell (leader). The best strategies for both instances show a remarkably high performance rate of 0.99. In one-dimensional case the number of cells N is often modulo-restricted, such as in the best-performing CA called the strategy of mirror particles, where N is restricted to 5 mod 6. We also analyze the dynamics of two-dimensional CAs by stability measures: the Derrida measure, and the damage spreading with a discrete version of Lyapunov stability. In general, the more complex the dynamics, the better-performing the CA. Furthermore, we identify fundamental limitations of leader election for one- and two-dimensional CAs. More precisely, we show that configurations that are symmetric or loosely-coupled are principally unsolvable. The proportion of these configurations, however, decreases dramatically with the system size. We enumerate such unsolvable configurations using linear algebra and group theory and formulate a universal upper bound on performance for the anonymous leader election problem in CA. Our results pave the way to new distributed algorithms that are more robust and efficient than state-of-the-art systems. Our cellular automata consist of only binary components, without any extra memory or communication capabilities, and therefore use minimal resources possible. Our findings are also relevant for better understanding leader election in nature, in order to model biological processes such as morphogenesis of cell differentiation. [less ▲]

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See detailConsensus and Pursuit-Evasion in Nonlinear Multi-Agent Systems
Thunberg, Johan UL

Doctoral thesis (2014)

Within the field of multi-agent systems theory, we study the problems of consensus and pursuit-evasion. In our study of the consensus problem, we first provide some theoretical results and then consider ... [more ▼]

Within the field of multi-agent systems theory, we study the problems of consensus and pursuit-evasion. In our study of the consensus problem, we first provide some theoretical results and then consider the problem of consensus on SO(3) or attitude synchronization. In Chapter 2, for agents with states in Rm, we present two theorems along the lines of Lyapunov’s second method that, under different conditions, guarantee asymptotic state consensus in multi-agent systems where the interconnection topologies are switching. The first theorem is formulated by using the states of the agents in the multiagent system, whereas the second theorem is formulated by using the pairwise states for pairs of agents in the multi-agent system. In Chapter 3, the problem of consensus on SO(3) for a multi-agent system with directed and switching interconnection topologies is addressed. We provide two different types of kinematic control laws for a broad class of local representations of SO(3). The first control law consists of a weighted sum of pairwise differences between positions of neighboring agents, expressed as coordinates in a local representation. The structure of the control law is well known in the consensus community for being used in systems of agents in the Euclidean space, and here we show that the same type of control law can be used in the context of consensus on SO(3). In a later part of this chapter, based on the kinematic control laws, we introduce torque control laws for a system of rigid bodies in space and show that the system reaches consensus when these control laws are used. Chapter 4 addresses the problem of consensus on SO(3) for networks of uncalibrated cameras. Under the assumption that each agent uses a camera in order to measure its rotation, we prove convergence to the consensus set for two types of kinematic control laws, where only conjugate rotation matrices are available for the agents. In these conjugate rotations, the rotation matrix can be seen as distorted by the (unknown) intrinsic parameters of the camera. For the conjugate rotations we introduce distorted versions of well known local parameterizations of SO(3) and show consensus by using control laws that are similar to the ones in Chapter 3, with the difference that the distorted local representations are used instead. In Chapter 5, we study the output consensus problem for homogeneous systems of agents with linear continuous time-invariant dynamics. We derive control laws that solve the problem, while minimizing a cost functional of the control signal. Instead of considering a fixed communication topology for the system, we derive the optimal control law without any restrictions on the topology. We show that for all linear output controllable homogeneous systems, the optimal control law uses only relative information but requires the connectivity graph to be complete and in general requires measurements of the state errors. We identify cases where the optimal control law is only based on output errors. In Chapter 6, we address the multi-pursuer version of the visibility pursuit-evasion problem in polygonal environments. By discretizing the problem and applying a Mixed Integer Linear Programming (MILP) framework, we are able to address problems requiring so-called recontamination and also impose additional constraints, such as connectivity between the pursuers. The proposed MILP formulation is less conservative than solutions based on graph discretizations of the environment, but still somewhat more conservative than the original underlying problem. It is well known that MILPs, as well as multi-pursuer pursuit-evasion problems, are NP-hard. Therefore we apply an iterative Receding Horizon Control (RHC) scheme, where a number of smaller MILPs are solved over shorter planning horizons. The proposed approach is illustrated by a number of solved examples. [less ▲]

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See detailArzt-Patienten-Kommunikation in einem mehrsprachigen Setting: Eine qualitative Studie
Bourkel, Elisabeth UL

Doctoral thesis (2014)

This dissertation addresses the view of general practitioners working in Luxembourg on possible language and culture barriers in their consultations. Furthermore the thesis deals with the doctors’ ... [more ▼]

This dissertation addresses the view of general practitioners working in Luxembourg on possible language and culture barriers in their consultations. Furthermore the thesis deals with the doctors’ perceptions of doctor-patient-communication in general, including further possible influencing factors (e.g., further doctor and patient factors or professional context). In addition the thesis focuses on the general practitioners’ ideas on intercultural competence, i.e. “the competence to act successfully in an intercultural encounter.” (Thomas & Simon, 2007, S. 136). The theoretical part of the thesis initially deals with the characteristics of the Luxembourg medical setting. Subsequently we present models concerning interpersonal communication and doctor-patient-communication in which the Communication Accommodation Theory (Giles et al., 1991) and the Three levels of doctor-patient-communication (Jain & Krieger, 2011) are considered in detail. Moreover, we explain the essential elements of doctor-patient-communication according to the Kalamazoo Consensus Statement (Makoul, 2001) and the Factors influencing doctor-patient-communication by Mead and Bower (2000). Furthermore, we discuss recent research on intercultural doctor-patient-communication. Finally, general concepts concerning intercultural competence in general and specific intercultural competence in the medical setting are presented. Through a synthesis of those models, we developed an integrative heuristic model of intercultural competence including its requirements and components (intercultural knowledge and skills). The objectives of the empirical study conducted in line with the present thesis, lead to research on (1) how general practitioners in Luxembourg describe the communication with their patients, (2) the awareness of Luxembourg general practitioners of cultural and language factors which may affect doctor-patient-communication and (3) the ideas of general practitioners in Luxembourg on intercultural competence. The research questions were analysed using a phenomenological approach. 16 general practitioners working in Luxembourg were interviewed. The interviews were analysed with a structuring resp. evaluative content analysis (Kuckartz, 2012; Mayring, 2010). The findings of the present study show that the doctors describe the elements of doctor-patient-communication in accordance with Makoul (2001). The model of influencing factors on doctor-patient-communication by Mead and Bower (2000) was almost entirely validated and new factors were added. Perceived as the three most relevant influencing factors in intercultural doctor-patient-communication with language barriers were: (1) patients with psychological problems (2) presence of translator in the consultation, (3) economic and time related components of consultations. Furthermore, the findings show that the majority of the interviewed doctors perceive a cultural influence on doctor-patient-communication in their Luxembourg practices. This influence can be described by the Model on influencing factors on intercultural communication by Schouten and Meeuweesen (2006). The greater portion of the interviewed doctors experienced language barriers in their professional daily routine. These language barriers can primarily be related to the patient’s medical condition, the doctor’s language proficiencies and migration background, the work content, as well as the language used in the consultation. Concerning intercultural competence, the practitioners described two kinds of intercultural skills: the skill to act proactively, e.g., which allows preventing misunderstandings, and the skill to react in intercultural conflict situations. Moreover, the findings show that the label “intercultural competence” is not known to all doctors. The relevance of the findings for the Luxemburg context as well as the differentiation between intercultural competence and professional resp. communication competencies in the medical consultation are discussed. The findings contribute to the development of existing models on intercultural doctor-patient-communication and intercultural competence which should be further explored in future studies. [less ▲]

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See detailMagnetische Neutronenkleinwinkelstreuung an inhomogenen Ferromagneten
Honecker, Dirk UL

Doctoral thesis (2014)

Small-angle neutron scattering (SANS) is a powerful method to investigate the magnetic microstructure in the bulk and on length scales between about 1 − 100 nm. SANS experiments are commonly realized with ... [more ▼]

Small-angle neutron scattering (SANS) is a powerful method to investigate the magnetic microstructure in the bulk and on length scales between about 1 − 100 nm. SANS experiments are commonly realized with an unpolarised or a polarised incident neutron beam, however, an analysis of the neutron spin state after the scattering process is usually not performed. As a result of the development of efficient 3He spin filters, a so-called longitudinal (one-dimensional) neutron-polarization analysis (POLARIS) at SANS instruments is now routinely available. The analysis of POLARIS data allows one to extract the Fourier components of the magnetization vector field. Experimental results on Fe-based two-phase nanocrystalline alloys serve as examples in order to demonstrate the capabilities of the POLARIS technique. In the investigated soft magnetic heterogeneous nanocomposites, the jump of the magnetization at the phase boundary between particles and matrix gives rise to a magnetostatic stray field, which represents a non-negligible source of spin disorder. As one of the central results of this dissertation, an analytical micromagnetic theory is presented, which allows one to analyze the magnetic-field-dependent SANS cross section of such particle-matrix-type ferromagnets. It is shown that the magnetic anisotropy field and the magnetostatic field decisively determine the properties of the magnetic SANS cross section, such as the asymptotic power-law behaviour, the range of spin-misalignment correlations and angular anisotropies. In particular, the theory explains the “clover-leaf”-shaped angular anisotropy, which is observed for several nanostructured magnetic materials and which can be attributed to jumps of the magnetization at internal interfaces. The micromagnetic aproach allows one to specify the field behaviour of the magnetic SANS and to quantitatively assess substantial features of the spin structure, for instance, the average exchange-stiffness constant and the mean magnetic anisotropy and magnetostatic fields. [less ▲]

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See detailSatellite Payload Reconfiguration Optimisation
Stathakis, Apostolos UL

Doctoral thesis (2014)

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See detailArgumentation in Flux: Modelling Change in the Theory of Argumentation
Rienstra, Tjitze UL

Doctoral thesis (2014)

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See detailEducating the World: International Organizations and the Construction of Lifelong Learning
Zapp, Mike UL

Doctoral thesis (2014)

While the 1960s and 1970s still knew permanent education (Council of Europe), recurrent education (OECD) and lifelong education (UNESCO), over the past 20 years, lifelong learning has become the single ... [more ▼]

While the 1960s and 1970s still knew permanent education (Council of Europe), recurrent education (OECD) and lifelong education (UNESCO), over the past 20 years, lifelong learning has become the single emblem for reforms in (pre-) primary, higher and adult education systems and international debates on education. Both highly industrialized and less industrialized countries embrace the concept as a response to the most diverse economic, social and demographic challenges – in many cases motivated by international organizations (IOs). Yet, literature on the nature of this influence, the diffusion of the concept among IOs and their understanding of it is scant and usually focuses on a small set of actors. Based on longitudinal data and a large set of education documents, the work identifies rapid diffusion of the concept across a heterogeneous, expansive and dynamic international field of 88 IOs in the period 1990-2013, which is difficult to explain with functionalist accounts. Based on the premises of world polity theory, this paper argues that what diffuses resembles less the bundle of systemic reforms usually associated with the concept in the literature and more a surprisingly detailed model of a new actor – the lifelong learner. [less ▲]

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See detailEssays on Irrational Behavior in Financial Markets
Martelin, Nicolas UL

Doctoral thesis (2014)

Personal preferences along with cognitive biases create the behavioral heterogeneity of a given market. In this thesis we study three markets that are completely different from each other and have their ... [more ▼]

Personal preferences along with cognitive biases create the behavioral heterogeneity of a given market. In this thesis we study three markets that are completely different from each other and have their own peculiarities: the stock market (US equity funds), the option market (S&P500 index options) and the art market (Impressionist and Modern, Post-war and Contemporary, American, and Latin American art indices). [less ▲]

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See detailMODEL-BASED STRESS TESTING FOR DATABASE SYSTEMS
Meira, Jorge Augusto UL

Doctoral thesis (2014)

Database Management Systems (DBMS) have been successful at processing transaction workloads over decades. But contemporary systems, including Cloud computing, Internet-based systems, and sensors (i.e ... [more ▼]

Database Management Systems (DBMS) have been successful at processing transaction workloads over decades. But contemporary systems, including Cloud computing, Internet-based systems, and sensors (i.e., Internet of Things (IoT)), are challenging the architecture of the DBMS with burgeoning transaction workloads. The direct consequence is that the development agenda of the DBMS is now heavily concerned about meeting non-functional requirements, such as performance, robustness and scalability. Otherwise, any stressing workload will make the DBMS lose control of simple functional requirements, such as responding to a transaction request~\cite{stem}. While traditional DBMS, including DB2, Oracle, and PostgreSQL, require embedding new features to meet non-functional requirements, the contemporary DBMS called as NewSQL present a completely new architecture. What is still lacking in the development agenda is a proper testing approach coupled with burgeoning transaction workloads for validating the DBMS with non-functional requirements in mind. The typical non-functional validation is carried out by performance benchmarks. However, they focus on metrics comparison instead of finding defects. In this thesis, we address this lack by presenting different contributions for the domain of DBMS stress testing. These contributions fit different testing objectives to challenge each specific architecture of traditional and contemporary DBMS. For instance, testing the earlier DBMS (e.g., DB2, Oracle) require incremental performance tuning (i.e., from simple setup to complex one), while testing the latter DBMS (e.g., VoltDB, NuoDB) require driving it into different performance states due to its self-tuning capabilities. Overall, this thesis makes the following contributions: 1) Stress TEsting Methodology (STEM): A methodology to capture performance degradation and expose system defects in the internal code due to the combination of a stress workload and mistuning; 2) Model-based Database Stress Testing (MoDaST): An approach to test NewSQL database systems. Supported by a Database State Machine (DSM), MoDaST infers internal states of the database based on performance observations under different workload levels; 3) Under Pressure Benchmark (UPB): A benchmark to assess the impact of availability mechanisms in NewSQL database systems. We validate our contributions with several popular DBMS. Among the outcomes, we highlight that our methodologies succeed in driving the DBMS up to stress state conditions and expose several related defects, including a new major defect in a popular NewSQL. [less ▲]

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See detailFormalising the twofold structure of a proactive system: Proof of concept on deterministic and probabilistic levels
Shirnin, Denis UL

Doctoral thesis (2014)

In the present work, we investigate the domain of Proactive computing, which may be characterised as a comparatively new computer science research paradigm. In our study, we understand and use the notion ... [more ▼]

In the present work, we investigate the domain of Proactive computing, which may be characterised as a comparatively new computer science research paradigm. In our study, we understand and use the notion of Proactive Computing as it was defined by Dr. David L. Tennenhouse. Conceptually, the architecture and main framework of our software system is entirely based on underlying concept characteristics of the given approach. Being a new research paradigm, proactive computing doesn’t possess yet a clear methodological support and approach repository, which may subsequently provide us with the necessary research techniques and methods. An application of the proactive computing approach thus requires a thorough empirical and theoretical investigation. The main objective of the current research project is to design an effective methodological framework, which will subsequently allow us to provide our proactive system with a scientifically rationalised proof of concept. An acquisition of the scientific evidence is primarily accomplished through the design, implementation and testing of all composite theoretical, methodological and functional aspects of the proactive system’s framework. The present study aims to emphasise the importance of designing a coherent multidisciplinary methodological framework, which is initially based on the expertise of two research fields, computer science and cognitive science domains. The main composite aspects of our methodological structure are based on the specific multidisciplinary techniques from both research fields. We investigate the proactive computing paradigm within the defining principles of deterministic and probabilistic approach orientations, where we additionally apply the techniques of the cognitive modelling approach. All designed and implemented computational mechanisms, together with the realised empirical studies, collectively aim to formalise the concept characteristics of the proactive system. Ultimately, an effective validation of the employed methodological frameworks and their underlying computational techniques provide our system with the necessary, scientifically rationalised proof of concept. [less ▲]

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See detailSUPPORTING INTERDISCIPLINARY SYSTEM DEVELOPMENT THROUGH INTEGRATED FUNCTION MODELLING
Eisenbart, Boris UL

Doctoral thesis (2014)

Industry is confronted with ever-changing and increasing demand of customers on global markets for integration of diverse functions into newly developed products and systems. As a consequence, companies ... [more ▼]

Industry is confronted with ever-changing and increasing demand of customers on global markets for integration of diverse functions into newly developed products and systems. As a consequence, companies increasingly often combine different engineering technologies into their products necessitating close collaboration of experts from various disciplines. New types of products, such as Product-Service Systems (PSS), which have become increasingly important in the recent past and combine (multi-disciplinary) products with associated services, extend interdisciplinary system development by including further disciplines. Problems in the (cross-disciplinary) exchange of information between the involved designers are considered one of the central risks posed to the success of interdisciplinary system development. Function modelling is expected to provide suitable means for the integration of different disciplines, as it addresses solution finding early in the design process and results in a first abstract representation of the system under consideration. However, a large variety of different and often incompatible function models can be found in the different disciplines, which hampers shared, cross-disciplinary function modelling. The research project presented in this thesis provides comprehensive insights into central barriers and enablers for cross-disciplinary function modelling in the development of mechatronic systems and PSS. Conducted research comprises comprehensive literature reviews of diverse function models and function modelling approaches proposed in disciplinary and interdisciplinary design approaches. The derived insights are complemented by empirical studies in ten companies active in diverse market areas, such as machine design, automotive, aerospace, and consumer product development. The empirical studies provide compelling insights into the actual application of function modelling in different disciplines and design departments, as well as into specific needs and preferences of practicing designers from different disciplines. A central contribution resulting from this research is the ”Integrated Function Modelling framework”, which is intended to address the identified needs and provide practicing designers with a flexible and generic modelling approach supporting interdisciplinary conceptual design. The project is concluded with an initial evaluation of the developed framework in industry and academia. [less ▲]

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See detailCu2ZnSnSe4 polymorphs and secondary phases: characterization by Raman spectroscopy and photoluminescence
Djemour, M'hamed Rabie UL

Doctoral thesis (2014)

Cu2ZnSn(S,Se)4 (CZTS/Se)has the necessary properties to be suitable as a thin film solar cell absorber. The reported record e ciencies for pure CZTSe are measured on CZTSe absorbers of di erent band gaps ... [more ▼]

Cu2ZnSn(S,Se)4 (CZTS/Se)has the necessary properties to be suitable as a thin film solar cell absorber. The reported record e ciencies for pure CZTSe are measured on CZTSe absorbers of di erent band gaps (0.96 eV and 1 eV as extracted from photoluminescence (PL), for example) although they were supposed to be the same material. This di fference in band gaps is usually explained by a diff erent order of the composing elements leading to crystal structures from other space groups (polymorphs) which have di erent band gaps. Various polymorphs and secondary phases are possible. This implies the importance of possessing tools to discernate the phases that tend to form whilst CZTSe is grown. This is one main goal of this thesis. The main measurement techniques employed during this thesis are Photoluminescence (PL) and Raman spectroscopy. Both are optical, contact-less and non-destructive characterization techniques. Following on from the first chapter which provides relevant background information about the di fferent polymorphs, secondary phases and measurement techniques used, the second chapter introduces the setup and the sample preparation techniques. The third chapter reports the fi rst results of this thesis: the discrimination of secondary phases encountered during the growth of CZTSe solar cell absorbers by Raman and PL. Chapter four discusses the Raman spectrum of CZTSe, especially focusing on the asymmetry of the mode of highest intensity, looking at the origins of this broadening. Additionally, a polarization and orientation Raman study is presented assigning the modes to their symmetry, therefore allowing the di erentiation between crystals from various polymorphs. The next chapter examines the luminescences attributed to CZTSe. An intensity dependent PL study assigns the various luminescences encountered to a mixture of band gaps. In the fi nal chapter, the findings reported on in this thesis are briefly summarized and discussed in the context of the ongoing research on the subject matter. [less ▲]

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See detailPhase segregation in Cu2ZnSnSe4 thin films for photovoltaic applications. The effects of precursor microstructure and selenium activity during selenization of electrodeposited metallic precursors.
Arasimowicz, Monika UL

Doctoral thesis (2014)

This thesis develops the synthesis of thin film copper-zinc-tin-selenide kesterite absorber layers, Cu2ZnSnSe4 (CZTSe), suitable for solar cell applications. The kesterites are highly sensitive to ... [more ▼]

This thesis develops the synthesis of thin film copper-zinc-tin-selenide kesterite absorber layers, Cu2ZnSnSe4 (CZTSe), suitable for solar cell applications. The kesterites are highly sensitive to stoichiometry deviations and most of the kesterite growth technologies suffer from the segregation of secondary phases, which can be detrimental to the performance of the solar cell. This thesis examines the phase segregation occurring during CZTSe absorber growth during a two-step electrodeposition – annealing process. A method towards reducing phase segregation in the CZTSe absorber is developed by manipulating the microstructure of Cu-Sn-Zn precursors and the annealing conditions. A power conversion efficiency improvement from 0 % to 5.94 % was possible by changing the microstructure of the metallic precursor from a bi-layered with Zn-rich alloy on the top to a matrix-type. This is explained by the higher reactivity of Zn with selenium vapour than Cu or Sn. The synthesis route used in this study consisted of three stages: sequential electrodeposition of Cu, Sn and Zn layers, soft pre-alloying of the resulting metallic stacks, and thermal annealing in the presence of selenium vapour. The pre-alloying step is introduced in order to develop uniform microstructure to the precursors by formation of Cu-Sn and Cu-Zn alloys. Depending on the stacking order of the metals in the electrodeposited precursors, two types of microstructure are developed during the pre-alloying process: a bi-layered structure with the Cu-Zn alloy on the top and the Cu-Sn alloy on the bottom and a matrix-type microstructure with the Zn-rich phase in the Sn-rich matrix. It is shown that the precursor microstructure determines the further segregation of phases during CZTSe growth. Using a rapid thermal annealing system (RTP) it is possible to resolve the mechanism of CZTSe formation at short time intervals. Identification and location of secondary phases is studied by four characterization techniques: XRD, Raman spectroscopy, SEM/EDX and SIMS. The influence of the partial pressure of selenium above the precursor on the CZTSe growth is investigated by theoretical computation and compared to experimental results. It is shown that the rate-limiting step of kesterite formation is the arrival of selenium species from the source to the precursor sample. This is correlated to the thermodynamic feasibility of the metal- vapour phase selenium reactions, since the selenium partial pressure above the sample will determine which phases are prone to form. The studies of the CZTSe formation mechanism show that Zn is the first metal to react with selenium vapour. This explains why the presence of Zn on the precursor surface enhances the ZnSe phase segregation during the CZTSe growth. [less ▲]

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See detailCertiCloud and JShadObf. Towards Integrity and Software Protection in Cloud Computing Platforms
Bertholon, Benoit UL

Doctoral thesis (2013)

A simple concept that has emerged out of the notion of heterogeneous distributed computing is that of Cloud Computing (CC) where customers do not own any part of the infrastructure; they simply use the ... [more ▼]

A simple concept that has emerged out of the notion of heterogeneous distributed computing is that of Cloud Computing (CC) where customers do not own any part of the infrastructure; they simply use the available services and pay for what they use. This approach is often viewed as the next ICT revolution, similar to the birth of the Web or the e-commerce. Indeed, since its advent in the middle of the 2000's, the CC paradigm arouse enthusiasm and interest from the industry and the private sector, probably because it formalizes a concept that reduces computing cost at a time where computing power is key to reach competitiveness. Despite the initiative of several major vendors to propose CC services (Amazon, Google, Microsoft etc.), several security research questions remain open to transform the current euphoria into a wide acceptance. Moreover, these questions are not always tackled from the user's point of view. In this context, the purpose of this thesis is to investigate and design novel mechanisms to cover the following domains: - Integrity and confidentiality of Infrastructure-as-a-Service (IaaS) infrastructures, to provide guarantees on programs and data running in a virtualised environment, either before, during or after a deployment on the CC platform. - Software protection on Software-as-a-Service (SaaS) and Platform-as-a-Service (PaaS) architectures, using code obfuscation techniques. This dissertation details thus two main contributions. The first one is the development and implementation of CertiCloud, a CC framework which relies on the concepts developed in the Trusted Computing Group (TCG) together with hardware elements, i.e., Trusted Platform Module (TPM) to offer a secured and reassuring environment within IaaS platforms. At the heart of CertiCloud reside two protocols: TCRR and VerifyMyVM. When the first one asserts the integrity of a remote resource and permits to exchange a private symmetric key, the second authorizes the user to detect trustfully and on demand any tampering attempt on its running VM. These protocols being key components in the proposed framework, their analysis against known cryptanalytic attacks has been deeply analysed and testified by their successful validation by AVISPA [1] and Scyther [66], two reference tools for the automatic verification of security protocols. The second major contribution proposed in this manuscript is an obfuscation framework named JShadObf, designed to improve the protection of Javascript-based software running typically on SaaS and PaaS platforms. This framework combines obfuscation transformations, code complexity measurements and Multi-Objective Evolutionary Algorithms (MOEAs) to protect Javascript code, the most ubiquitous programming language at the heart of most modern web services deployed over those CC infrastructures such as Google Office Apps, Dropbox or Doodle. [less ▲]

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See detailStates of Education: Reflections on the Relationship between Welfare State and Education in Finland and the Federal Republic of Germany
Gardin, Matias UL

Doctoral thesis (2013)

This PhD thesis examines the impact of political ideologies on the welfare state developments of the Republic of Finland and Federal Republic of Germany. It explores the issue by asking whether different ... [more ▼]

This PhD thesis examines the impact of political ideologies on the welfare state developments of the Republic of Finland and Federal Republic of Germany. It explores the issue by asking whether different ideas of ruling parties mattered in these developments or were there other factors, such as the level of economic strength, which became more influential in explaining cross-national welfare variations. Whereas mainstream analysts of comparative social policy since the early 1990s have taken for granted that politics mattered in the immediate post-war era reflecting the more pronounced left-right, catholic-protestant and other historical cleavages, this research moves beyond the oversimplified traditional welfare regime typologies and instead considers how welfare systems became intertwined with other more control-focused aspects of state development: in effect, whether and how they became instruments of discipline through educating citizens. Drawing on the Foucauldian idea of power of normalisation – and using educational expansion of the 1960s as a case study – it is suggested that there are aspects of the development of Finnish and West German policing which had a direct bearing on the emergence of the welfare state. [less ▲]

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See detailComputational Tools for Mass Spectrometry Based Metabolic Profiling
Wegner, André UL

Doctoral thesis (2013)

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See detailRegulation and activity of the tumor suppressor protein Tes
Hadzic, Ermin UL

Doctoral thesis (2013)

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See detail(How) can formal modelling improve educational achievement judgments?
Kovacs, Carrie UL

Doctoral thesis (2013)

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See detailLes marques modales dans les chats: étude sémiotique et pragmatique des interjections et des émoticônes dans un corpus de conversations synchrones en ligne
Halté, Pierre UL

Doctoral thesis (2013)

The purpose of this thesis is to study subjectivity markers in an online chat corpus : interjections and emoticons. First, we will study the semiotic and pragmatic specificities of this type of online ... [more ▼]

The purpose of this thesis is to study subjectivity markers in an online chat corpus : interjections and emoticons. First, we will study the semiotic and pragmatic specificities of this type of online conversation ; then we will propose a semiotic and pragmatic approach of interjections and emoticons. We will show that, even if there are a few differences between those two types of signs – interjections are definitely part of verbal language, whereas emoticons are iconic imitations of gestures and mimics – they share numerous traits. The study of those signs will lead us to wonder about their semiotic status, from icon to index, but also about their pragmatic functions : how they allow to perform, to show instead of describing, how they allow the users to express their subjectivity regarding a propositional content, etc. We hope that this study will contribute to enlarge the knowledge we have of emoticons, but also the views researchers have on the relationships between language and gestures / mimics, which, according to us, should be brought closer, and not further apart. [less ▲]

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See detailPour un droit des sociétés coopératives et mutualistes en OHADA. Contribution à l'élaboration d'un droit de l'économie sociale et solidaire
Tadjudje, Willy UL

Doctoral thesis (2013)

Legislation plays a very important role in the economic and social development. This is why the Law must be constantly adjusted to suit the particular circumstances of its recipients. This statement ... [more ▼]

Legislation plays a very important role in the economic and social development. This is why the Law must be constantly adjusted to suit the particular circumstances of its recipients. This statement applies to all branches of law, including the law of social and solidarity economy organizations. For a long time, they have been neglected. But in recent years, due to their contribution to the fight against the problems faced by Africa (unemployment, poverty, financial and social exclusion, etc.), these organizations are increasingly considered by legislators. There were legislations applicable to cooperatives in all States Parties to the OHADA Treaty, both before and after the independences. Similarly, in some countries, in the 1990s, the first laws governing mutual societies were adopted. However, these frameworks were generally described as inadequate or insufficient. That was precisely why OHADA decided to integrate cooperatives and mutual societies in its legislative agenda. Its task was to modernize the cooperative law and to fill legislative gaps in mutual society's law. The project was launched in 2001. But between 2004 and 2007, a lively discussion took place and led to the exclusion of mutual society from the OHADA legislation. Therefore, on 15th December 2010, was adopted a OHADA Uniform Act on cooperatives law only. Following the rejection of mutual societies by OHADA, the UEMOA continued its draft law on the same subject, which was adopted in 2009. The objective of this research is to criticize the withdrawal of mutual societies from the OHADA legislation and to plead for a reintroduction of a uniform act on cooperatives and mutual societies. At the time, the OHADA had relied on three main reasons to oust mutual societies: the difficulty to build rules applicable to two legal forms of organization in a single text, the fact that mutual societies are not part of business law that OHADA is supposed to harmonize and the initiation of a legislation on mutual societies in the UEMOA zone at the same period. Throughout the first part of this research, we show that cooperatives and mutual societies share a broad consensus, which is sufficient to demonstrate that they can be treated together under a unique law. In the second part, we note that mutual societies can take the legal form of society, which integrates them in the OHADA law. Also, because of the symbolic supremacy of the OHADA over the UEMOA, we explain how the OHADA legislator could consult his counterpart from the UEMOA in the perspective to avoid duplicative legislations. Once the establishment of this framework, we discussed the process of building such a uniform act. We found that the context is difficult because of the failure of previous experiences, and the need to build a suitable law. Despite this difficult environment, rules can be explored. The appropriate way is to first set the common provisions and then the particular ones, knowing that all of them may help to pave the way for a law of social and solidarity economy. [less ▲]

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See detailLiquidity risk in capital markets
Busch, Thomas UL

Doctoral thesis (2013)

This thesis focuses on liquidity risk in capital markets. The main aim is to help practitioners to better understand and manage liquidity risk by analyzing the following three topics: modeling ... [more ▼]

This thesis focuses on liquidity risk in capital markets. The main aim is to help practitioners to better understand and manage liquidity risk by analyzing the following three topics: modeling correlations in a Liquidity Adjusted VaR (L − VaR) (Chapter Three), impact of regulatory interventions on stock liquidity (Chapter Four) and liquidity commonality and option prices (Chapter Five). The first topic focuses on an appropriate way to measure expected stock losses by considering liquidity risk (see Chapter Three). The need for a new measure, which also includes stock liquidity, is based on the concern of investors only being able to sell stock at a huge discount or not at all. In reaction, various papers with new methodologies have been published, including the liquidity adjusted Value at Risk (L − VaR) models proposed by Bangia et al. (1998) and Ernst et al. (2012). Based on their approach, we analyze different ways to extend these models and to optimize performance. This is done using advanced conditional volatility models like AR − GARCH and AR − GJR models and by considering correlations between spread and return data. The new model is called correlation and liquidity adjusted VaR (CL – VaR) and shows (based on a five-year observation period) better performance compared to the models by Bangia et al. (1998) and Ernst et al. (2012). The models are calculated and back-tested using unique data called Xetra Liquidity Measure (XLM) provided by Deutsche Börse. The collapse of Lehman Brothers in 2008 marked the beginning of a financial crisis affecting the entire world of finance. This period is characterized by increasing fear of further defaults by corporations (including banks) or even by countries. In reaction, investors began shifting their assets to more stable and secure investments and this resulted in stock market crashes. Various interventions were made by government institutions to restore stability. The target of the second topic is to analyze the impact of these interventions on liquidity (measured by volume-weighted bid-ask spreads) and market reaction (measured by returns) at the announcement date (see Chapter Four). In the event, we study abnormal changes of stocks listed on the Dax. The interventions which we consider are published by the Federal Reserve Bank (FED) in the form of a crisis time-line. Here they are further combined to the following categories: bank liability guarantees, liquidity and rescue interventions, unconventional monetary policy and other market intervention. The results show that, for example, the market reacts positively to liquidity and rescue interventions, whereas bank liability guarantees reduce liquidity. In addition, we show that international events have a significant impact on the domestic market in a "spillover effect". By analyzing the spreads of different traded volumes, an asymmetric increase can be detected at the announcement date. The last topic focuses on the link between equity and option markets (see Chapter Five). There we analyze, on one hand, the link between stock market liquidity and option prices and, on the other hand, the impact of liquidity commonality in equity and option markets. We can show that systematic liquidity (rather than idiosyncratic liquidity) gives a better explanation of changes in “at-the-money” implied volatility. This effect was especially strong during the financial crisis in 2008. Another result is that liquidity risk of higher traded stock volumes is not properly reflected in the option price. This can result in higher hedging costs, as mentioned by Certin et al. (2006). To shed more light into liquidity commonality within the stock market we calculate the LiqCom measure as mentioned by Chordia et al. (2000). The results show a continuously changing liquidity commonality which decreases with increasing traded volume. This is because the market maker focuses for bigger stock positions more on the idiosyncratic liquidity risks while for smaller stock positions the systematic liquidity risk is more important. We confirmed our findings with a robustness check. [less ▲]

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See detailImpact des glucocorticoïdes plasmatiques sur la maturation et le fonctionnement de l'inhibition spinale GABAergique
Zell, Vivien UL

Doctoral thesis (2013)

Glucocorticoids (GC) such as corticosterone (CORT) in rats are synthetized following stress and HPA axis activation and are part of organisms response to homeostasis perturbations. Furthermore, GC can ... [more ▼]

Glucocorticoids (GC) such as corticosterone (CORT) in rats are synthetized following stress and HPA axis activation and are part of organisms response to homeostasis perturbations. Furthermore, GC can also alter pain perception. [less ▲]

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See detailEnforced privacy: from practice to theory
Dong, Naipeng UL

Doctoral thesis (2013)

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See detailPaysages silencieux dans le roman réaliste (1850-1900)
Thiltges, Sébastian UL

Doctoral thesis (2013)

En Europe et depuis le romantisme, les arts et la littérature font apparaître le paysage silencieux comme une représentation esthétique, une création culturelle ou un espace reflétant une expérience ... [more ▼]

En Europe et depuis le romantisme, les arts et la littérature font apparaître le paysage silencieux comme une représentation esthétique, une création culturelle ou un espace reflétant une expérience singulière de communion avec la nature. D’une part, le paysage, qui se définit à partir du point de vue du sujet, est par essence subjectif. D’autre part, le silence paysager, dans son acception générale d’absence de bruit ou de son, est un phénomène théorique, non définissable et non mesurable objectivement. En réaction à ce qu’il dénonce comme une projection lyrique de la subjectivité humaine sur le monde contemplé, le réalisme propose l’exploration scientifique de la nature observée et vise une pratique descriptive basée de prime abord sur la représentation objective du paysage. Au silence romantique, dans lequel tout est langage, s’oppose un silence réaliste, musellement du créateur et constat du mutisme et de l’indifférence du monde environnant. Les influences de la science et du positivisme ont métamorphosé le regard de l’être humain sur le monde sensible et ont ouvert de nouveaux mondes qu’explorent les romanciers. Simultanément, la disparition de la figure humaine dans l’art paysager témoigne du bouleversement épistémique qui engendre une nouvelle révolution copernicienne dans laquelle l’homme n’est plus le centre du monde et de la connaissance. Le détournement réaliste du topos romantique est problématique en ce qu’il refuse la représentation subjective de la nature, qui pourtant s’est avérée être un modèle efficace, tout en butant sur l’impossible représentation objective d’un motif insaisissable. De ce double échec constitutif de la modernité du réalisme naît une poétique descriptive du paysage qui offre une vision nouvelle du monde, basée non seulement sur le positivisme et le déterminisme, mais également sur la contingence du monde, témoignant d’un certain scepticisme envers les signes. Dans le sillage de ces évolutions esthétiques et poétiques, le regard et l’horizon du lecteur sur le roman se transforment également. La description du paysage silencieux constitue un espace textuel dans lequel le sens est perpétuellement mis en suspens. Les analogies entre l’écoute du paysage et l’écoute du texte romanesque, entre le paysage silencieux et la lecture silencieuse, permettent de définir une phénoménologie de la description réaliste du paysage silencieux. La construction d’un paysage polysensoriel ainsi que l’association du paysage et du silence, deux concepts pluridisciplinaires, soulignent l’importance de la perception et mettent en exergue la figure de l’interprétant. Le lecteur reconnaît et comprend la référentialité de la description littéraire réaliste, tout en faisant l’expérience, au sein du silence de la page, de la face sonore du signifiant poétique. De la description du paysage silencieux se dégagent un modèle heuristique et un enseignement de lecture, tant au niveau diégétique – les personnages ou le narrateur tentant de percer le silence du paysage – que textuel – le lecteur déchiffrant la signifiance de la description romanesque. [less ▲]

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See detailNetwork analysis to model diseases and cellular reprogramming for therapeutic intervention
Crespo, Isaac UL

Doctoral thesis (2013)

Applications of network analysis to the study of disease can be divided into two main categories: disease description, including characterisation, diagnosis and prognosis; and disease treatment, including ... [more ▼]

Applications of network analysis to the study of disease can be divided into two main categories: disease description, including characterisation, diagnosis and prognosis; and disease treatment, including drug target discovery and cellular reprogramming, together with its applications to regenerative medicine. In this dissertation, I will critically discuss some research projects on which I have been working during my PhD program. In correspondence with the two aforementioned categories, these projects can be broken down into two different blocks of content, with the common goal of acquiring insights into the study of disease. In the first block of contents, corresponding with Chapter 2, I will explain and discuss novel strategies for network-based analysis and modelling which have been applied for disease description and characterisation in different case-studies, namely the metabolic syndrome, prion disease and the epithelial to mesenchymal transition in breast cancer. Indeed, these projects exploited the evolutionary conservation of motifs of regulatory interactions and consistency between computed and experimentally validated expression so as to reconstruct dynamical models and create a network-based characterisation of the corresponding systems. With regards the second block of content, corresponding with Chapter 3, I explain and discuss novel computational methods which have been developed during my PhD program to address the task of the artificial induction of cellular reprogramming; something with a wealth of potential applications when it comes to the creation of disease models and in the field of regenerative medicine. Within the general conclusion discussion focuses on the fact that, although the methodology explained in this work was developed in the context of disease study, one may find the application of some of these ideas and strategies fitting for other problems. Indeed, the same principles applied to detect driver genes capable of changing the cell phenotype when perturbed can also be applied to control biological living systems for basic research or industrial purposes. These principles could also be potentially extended to higher level systems than the cellular level (tissue or cell population level). [less ▲]

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See detailAttack-defense trees
Schweitzer, Patrick UL

Doctoral thesis (2013)

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See detailDevelopment of adhesives constitutive material laws for the assessment of bonded steel to glass partial composite beams
Dias, Vincent UL

Doctoral thesis (2013)

Glass products are widely employed in transparent facade and roof structures as tertiary non-structural elements despite their large in-plane compressive resistances. To structurally implement them in ... [more ▼]

Glass products are widely employed in transparent facade and roof structures as tertiary non-structural elements despite their large in-plane compressive resistances. To structurally implement them in building, tensile stresses must be consequently reduced or avoided. The later requirements would be fulfilled by realizing composite steel to glass connection, whose principal difficulty would arose from the connection mean which should be sufficiently rigid to transfer shear forces and sufficiently soft to not alter the glazing. Two possible jointing methods were envisaged and investigated to accomplish this assembly and overcome this problem, i.e. a linear adhesive bonding of the steel and glass parts and a mixed mechanical-adhesive connection. In consequence, two potential adhesives were selected, a silicone elastomer and a UV-curing acrylic thermoset. A lack of knowledge with regards to their mechanical properties implied the conduction of several series of quasi-static, cyclic and long-term relaxation tests. The possible influence of external parameters, such as temperature, humidity or UV-radiation, on their uniaxial tension/compression and shear behaviours was evaluated with the help of statistical methods applied on the results of Taguchi design of experiments tables. With the invariance of the silicone properties, a new hyperelastic quasi-incompressible constitutive material law accounting for the quasi-static and post Mullins effect behaviour was developed and validated with finite element analyzes of the small-scale experimental tests. The UV-acrylic was however found strongly dependent on the loading rate and one-dimensional models were suggested to describe the quasi-static tension and shear behaviour under specific rates. In reason of the poor long-term properties of the UV-acrylic, only the silicone was regarded for the construction of the two types of composite beams. Pre-evaluations issued from numerical simulations including the developed material law accommodated perfectly with theoretical data and approached the large-scale tests results by considering the manufacturing operations conducted on the steel beam. [less ▲]

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See detailTowards the Formal Verification of Model Transformations: An Application to Kermeta
Amrani, Moussa UL

Doctoral thesis (2013)

Model-Driven Engineering (MDE) is becoming a popular engineering methodology for developing large-scale software applications, using models and transformations as primary principles. MDE is now being ... [more ▼]

Model-Driven Engineering (MDE) is becoming a popular engineering methodology for developing large-scale software applications, using models and transformations as primary principles. MDE is now being successfully applied to domain-specific languages (DSLs), which target a narrow subject domain like process management, telecommunication, product lines, smartphone applications among others, providing experts high-level and intuitive notations very close to their problem domain. More recently, MDE has been applied to safety-critical applications, where failure may have dramatic consequences, either in terms of economic, ecologic or human losses. These recent application domains call for more robust and more practical approaches for ensuring the correctness of models and model transformations. Testing is the most common technique used in MDE for ensuring the correctness of model transformations, a recurrent, yet unsolved problem in MDE. But testing suffers from the so-called coverage problem, which is unacceptable when safety is at stake. Rather, exhaustive coverage is required in this application domain, which means that transformation designers need to use formal analysis methods and tools to meet this requirement. Unfortunately, two factors seem to limit the use of such methods in an engineer’s daily life. First, a methodological factor, because MDE engineers rarely possess the effective knowledge for deploying formal analysis techniques in their daily life developments. Second, a practical factor, because DSLs do not necessarily have a formal explicit semantics, which is a necessary enabler for exhaustive analysis. In this thesis, we contribute to the problem of formal analysis of model transformations regarding each perspective. On the conceptual side, we propose a methodological framework for engineering verified model transformations based on current best practices. For that purpose, we identify three important dimensions: (i) the transformation being built; (ii) the properties of interest ensuring the transformation’s correctness; and finally, (iii) the verification technique that allows proving these properties with minimal effort. Finding which techniques are better suited for which kind of properties is the concern of the Computer-Aided Verification community. Consequently in this thesis, we focus on studying the relationship between transformations and properties. Our methodological framework introduces two novel notions. A transformation intent gathers all transformations sharing the same purpose, abstracting from the way the transformation is expressed. A property class captures under the same denomination all properties sharing the same form, abstracting away from their underlying property languages. The framework consists of mapping each intent with its characteristic set of property classes, meaning that for proving the correctness of a particular transformation obeying this intent, one has to prove properties of these specific classes. We illustrate the use and utility of our framework through the detailed description of five common intents in MDE, and their application to a case study drawn from the automative software domain, consisting of a chain of more than thirty transformations. On a more practical side, we study the problem of verifying DSLs whose behaviour is expressed with Kermeta. Kermeta is an object-oriented transformation framework aligned with Object Management Group standard specification MOF (Meta-Object Facility). It can be used for defining metamodels and models, as well as their behaviour. Kermeta lacks a formal semantics: we first specify such a semantics, and then choose an appropriate verification domain for handling the analysis one is interested in. Since the semantics is defined at the level of Kermeta’s transformation language itself, our work presents two interesting features: first, any DSL whose behaviour is defined using Kermeta (more precisely, any transformation defined with Kermeta) enjoys a de facto formal underground for free; second, it is easier to define appropriate abstractions for targeting specific analysis for this full-fledged semantics than defining specific semantics for each possible kind of analysis. To illustrate this point, we have selected Maude, a powerful rewriting system based on algebraic specifications equipped with model-checking and theorem-proving capabilities. Maude was chosen because its underlying formalism is close to the mathematical tools we use for specifying the formal semantics, reducing the implementation gap and consequently limiting the possible implementation mistakes. We validate our approach by illustrating behavioural properties of small, yet representative DSLs from the literature. [less ▲]

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See detailDerived D-Geometry and Field Theory
Bonavolonta, Giuseppe UL

Doctoral thesis (2013)

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See detailThe relationship between intelligence and health in Luxembourg
Wrulich, Marius UL

Doctoral thesis (2013)

Even though the general health and life expectancies of Western societies have been consistently rising throughout the 20th century, socioeconomic health inequalities continue to persist. Individuals from ... [more ▼]

Even though the general health and life expectancies of Western societies have been consistently rising throughout the 20th century, socioeconomic health inequalities continue to persist. Individuals from lower socioeconomic groups have substantially worse health and an increased mortality risk compared to individuals from higher socioeconomic groups. As external factors such as material resources cannot fully account for these health inequalities, personal factors such as intellectual abilities have been suggested as additional important explanatory factors. The research field concerned with the effects of intelligence on different health outcomes is called cognitive epidemiology. Results from this field of research have now established that childhood intelligence is an important predictor of different health outcomes in adulthood. Specifically, children with higher intelligence exhibit a lower mortality risk and enjoy better health in adulthood compared to children with lower childhood intelligence. Despite these findings, several open research questions remain: (1) Almost all previous studies on the relation between childhood intelligence and adult health have been conducted in English-speaking or Scandinavian countries. Can these findings be generalized to countries with different cultural backgrounds, health-care systems, or levels of social mobility? Specifically, Luxembourg offers universal access to quality health care, which may compensate for some of the effects of individual differences in intelligence on health, and as a result, intelligence may lose its impact. (2) Physical health is a multidimensional concept with three distinct subdimensions: a physical subdimension (e.g., presence of diagnosed diseases, number of doctor visits in a certain time period), a subjective subdimension (e.g., satisfaction with one’s own health), and a (social-)functional subdimension (e.g., unimpaired participation in social and occupational activities or performing household tasks). Most previous studies on the relation between intelligence and health outcomes have focused on the physical health subdimension. Hence, considerably less is known about the effects of intelligence on the functional and subjective subdimensions. This issue is of particular importance as childhood intelligence may be differentially related to different aspects of adult health. (3) It remains unclear whether different facets of childhood intelligence (e.g., general, fluid, or crystallized intelligence) predict adult health equally well, as most studies on the topic have used only global measures of childhood intelligence to predict later health. However, investigating different facets of childhood intelligence as predictors of adult health would provide insights into which facets of intelligence are important in personal health management and could be targeted by interventions. (4) Despite considerable evidence that has emphasized the relevance of education and further indicators of subsequent socioeconomic status (SES) as potential mediators between childhood intelligence and later health outcomes, previous research has yielded inconsistent results regarding the extent to which these relations are mediated. Some studies have reported pronounced mediation via education and subsequent SES, yet others have reported little or no mediation. However, knowing and understanding which mediational mechanisms underlie the intelligence-health relation and the extent to which they mediate this relation are crucial for applying findings from cognitive epidemiology to public health. (5) As is the case for studies on intelligence and health outcomes, most studies on the relation between intelligence and mortality risk have been conducted in English-speaking or Scandinavian countries. Thus, it remains unclear whether the results of these studies can be generalized to Luxembourg. Further, there is controversy about whether the effect of intelligence on mortality exists across the entire range of intelligence scores or whether individuals at the lower end of the intelligence distribution constitute a risk group with a particularly high mortality risk. Identifying potential risk groups is crucial for determining which groups should be targeted by interventions to reduce inequalities in health and mortality risk. The present Ph.D. thesis addressed these five research questions with three distinctive studies. Study I investigated whether childhood intelligence would predict adult physical, functional, and subjective health 40 years later even when controlling for the effects of childhood SES. Study I also investigated whether a global measure of childhood general intelligence or whether more specific facets such as fluid and crystallized intelligence would better predict adult health. Study II investigated whether and the extent to which educational attainment and SES in adulthood would mediate the effects of childhood intelligence on the three adult health dimensions. Study III investigated whether childhood intelligence would predict adult mortality risk when controlling for childhood SES and whether individuals at the lower end of the intelligence distribution would constitute a risk group with a particularly high mortality risk. All three studies were embedded in the general framework of the Luxembourgish MAGRIP project. This large-scale longitudinal study comprised two waves of measurement over a 40-year period. In the first wave of measurement in 1968, detailed intelligence and socioeconomic data were collected on a randomly selected nationally representative sample comprising 2,824 students at the end of their primary education (M = 11.9 years; SD = 0.6 years; 50.1% male). In the second wave conducted 40 years later, 745 participants (M = 51.7 years, SD = 0.6 years; 46.7% male) provided data on their educational careers, adult SES, and functional, subjective, and physical health. In addition, the mortality rate was established for the participants in the first wave of MAGRIP: 166 participants (69.9% male) had died. The results of the three studies demonstrated that childhood intelligence, particularly childhood fluid intelligence, showed a significant association with adult health: Lower childhood intelligence scores were associated with worse health outcomes on all three dimensions of physical, functional, and subjective health in adulthood, even when controlling for childhood SES. These effects were entirely mediated via educational attainment and adult SES, with educational attainment playing a crucial role in these mediational processes. Further, childhood intelligence showed a significant association with adult mortality such that lower childhood intelligence scores were associated with an increased mortality risk. This effect was particularly strong among men at the lower end of the intelligence distribution. These results suggest that even high-quality public health care cannot fully offset the cumulative effects of childhood intelligence on adult health. Intelligence may thus be an important explanatory factor for socioeconomic inequalities in health. Promising means for reducing these socioeconomic health inequalities consist of interventions that are designed to improve childhood intelligence, to improve environments for childhood physical and intellectual development, and to make public health care and preventive measures or treatments accessible to adults with lower intellectual abilities. [less ▲]

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See detailThe impact of childhood intelligence on subjective well-being in adulthood
Chmiel, Magda UL

Doctoral thesis (2013)

Detailed reference viewed: 65 (13 UL)
See detailGame-theory and Logic for Non-repudiation Protocols and Attack Analysis
Melissen, Matthijs UL

Doctoral thesis (2013)

Detailed reference viewed: 58 (11 UL)
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See detailModelling Metabolic Interactions in the Legume-Rhizobia Symbiosis
Pfau, Thomas UL

Doctoral thesis (2013)

With the emergence of “omics” techniques, it has become essential to develop tools to utilise the vast amount of data produced by these methods. Genome-scale metabolic models represent the mathematical ... [more ▼]

With the emergence of “omics” techniques, it has become essential to develop tools to utilise the vast amount of data produced by these methods. Genome-scale metabolic models represent the mathematical essence of metabolism and can easily be linked to the data from omics sources. Such models can be used for various analyses, including the investigation of metabolic responses to changing environmental conditions. Legumes are known for their ability to form a nitrogen-fixing symbiosis with rhizobia, a vital process that provides the biosphere with the majority of its nitrogen content. In the present thesis, a genome-scale metabolic model for the legume Medicago truncatula was reconstructed, based on the annotated genome sequence and the MedicCyc database. A novel approach was employed to define the compartmentalisation of the plant’s metabolism. The model was used to calculate the biosynthetic costs of biomass precursors (e.g. amino acids, sugars, fatty acids, nucleotides), and its capability to produce biomass in experimentally observed ratios was demonstrated using flux balance analysis. Further investigation was carried out into how the biosynthesis fluxes and costs change with respect to different nitrogen sources. The precise charge balancing of all reactions in the model allowed the investigation of the effects of charge transport over the cellular membrane. The simulations showed a good agreement with experimental data in using different sources of nitrogen (ammonium and nitrate) to minimise the charge transport of the membrane. To allow the investigation of the symbiotic relationship, two rhizobial models were used. The first model, for Sinorhizobium meliloti, was reconstructed from the MetaCyc database (MC-model); the second model was a recently published model for S. meliloti specialised for symbiotic nitrogen fixation (SNF-model). Combined models were created for both rhizobial networks using a specialised nodule submodel of the plant model. Potential interactions were extracted from the literature and investigated, with the analysis suggesting that oxygen availability is the main limitation factor in symbiotic nitrogen fixation. Within the analysis the SNF-model appeared to be too restricted and lacking the potential for sufficient nitrogen fixation; therefore, further analysis was carried out using the MC-model, upon which it was observed that the availability of oxygen can also influence how nitrogen is supplied to the plant. At high oxygen concentrations ammonia is the primary form of nitrogen supplied by the rhizobium. However, the simulations, in accordance with experimental data, show that at lower concentrations of oxygen, alanine takes precedence. The findings also support the concept of amino acid cycling as a potential way to improve nitrogen fixation. The more flexible MetaCyc based model has allowed other potential genetic engineering approaches for higher nitrogen fixation yields to be proposed. [less ▲]

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See detailZUM TRAGVERHALTEN VON VERBUNDDECKEN MIT HOLZLEICHTBETON IM HOCHBAU
May, Andreas UL

Doctoral thesis (2013)

Detailed reference viewed: 41 (9 UL)
See detailZum Tragverhalten von Verbunddecken mit Holzleichtbeton im Hochbau
May, Andreas UL

Doctoral thesis (2013)

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See detailMolecular Eco-Systems Biology of Lipid Accumulating Microbial Communities in Biological Wastewater Treatment Plants
Roume, Hugo UL

Doctoral thesis (2013)

Biological wastewater treatment is based on the use of microorganisms capable of intense metabolic activity that results in the removal of a large proportion of organic and inorganic contaminants. Given ... [more ▼]

Biological wastewater treatment is based on the use of microorganisms capable of intense metabolic activity that results in the removal of a large proportion of organic and inorganic contaminants. Given copious amounts of energy-dense organic molecules such as lipids accumulated by the microbial biomass, chemical energy may be directly harnessed from this for biofuel production. Here, lipid accumulating organism (LAO)-enriched microbial communities were studied using a molecular eco-systems biology approach. This involved the development of necessary methodologies including a new comprehensive biomolecular extraction method, yielding high-quality DNA, RNA, proteins and metabolites, as well as bioinformatic approaches for integrating and analysing the derived high-throughput genomic, transcriptomic, proteomic and metabolomic data. At the inception of the project, a full-scale wastewater treatment plant (WWTP) system with a strong presence of LAOs especially during winter months, i.e. the Schifflange WWTP (Esch-sur-Alzette, Luxembourg), was identified and selected for further study. 16S rRNA amplicon sequencing highlighted the presence of ubiquitous lipid accumulating bacteria closely related to Candidatus Microthrix parvicella which increase in abundance from autumn to winter over other highly abundant community members belonging to Alkanindiges spp. and Acinetobacter spp. In order to elucidate compositional, genetic and functional differences between autumn and winter LAO communities, a comparative integrative omic analysis was carried out on rationally selected autumn and winter LAO community samples. The results from metabolomic/lipidomic analyses between intra- and extracellular compartments support previous models of uptake of unprocessed long chain fatty acids (LCFAs) from the wastewater environment and their storage as triacyglycerols within LAOs. Furthermore, a tailored computational framework for the integration of multi-omic datasets into reconstructed community-wide metabolic networks and models was developed. The resulting networks provide overviews of functional capacity of the sampled LAO communities by incorporating gene copy numbers, transcript levels and protein frequency across the two studied environmental conditions. The identification of genes overexpressed, strongly associated with a specific season and/or possessing a high clustering coefficient suggests the existence of keystone genes, analogous to keystone species in species interaction networks. Examples of such keystone genes in the context of the LAO communities include genes coding for proteins involved in nitrogen and glycerolipid metabolism. The existence of such keystone genes opens up exciting possibilities for prediction and control strategies of microbial communities at the dawn of the field of Eco-Systems Biology. [less ▲]

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See detailDirect and Indirect Measures of Learning in Visual Search
Reuter, Robert UL

Doctoral thesis (2013)

In this thesis, we will explore direct and indirect measures of learning in a visual search task commonly called contextual cueing. In the first part, we present a review of the scientific literature on ... [more ▼]

In this thesis, we will explore direct and indirect measures of learning in a visual search task commonly called contextual cueing. In the first part, we present a review of the scientific literature on contextual cueing, in order to give the readers of this thesis a better general idea of existing evidence and open questions within this relatively new research field. The aims of our own experimental studies presented in the succeeding chapters are the following ones: (1) to replicate and extend the findings described in the various papers by Marvin Chun and various colleagues on contextual cueing of visual attention; (2) to explore the nature of memory representations underlying the observed learning effects, especially whether learning is actually implicit and whether memory representations are distinctive, episodic and instance-based or rather distributed, continuous and graded; (3) to extend the study of contextual cueing to more realistic visual stimuli, in order to test its robustness across various situations and validate its adaptive value in ecologically sound conditions; and (4) to investigate whether such knowledge about the association between visual contexts and “meaningful” locations can be (automatically) transferred to other tasks, namely a change detection task. In a first series of four experiments, we tried to replicate the documented contextual cueing effect using a wide range of various direct measures of learning (tasks that are supposed to be related to explicit knowledge) and we systematically varied the distinctiveness of context configurations to study its effect on both direct and indirect measures of learning. We also ran a series of neural network simulations (briefly described in the general discussion of this thesis), based on a very simple association-learning mechanism, that not only account for the observed contextual cueing effect, but also yield rather specific predictions about future experimental data: contextual cueing effects should also be observed when repetitions of context configurations are not perfect, i.e., the networks were able to react to slightly distorted versions of repeating contexts in a similar way than they did to completely identical contexts. Human participants, we conjectured, should therefore (if the simple connectionist model captures some relevant aspects of the contextual cueing effect) become faster at detecting targets surrounded by context configurations that are only partially identical from trial to trial compared to those trials where the context configurations were randomly generated. These predictions were tested in a second series of experiments using pseudo-repeated context configurations, where some distractor items were either displaced from trial to trial or their orientation changed, while conserving their global layout. In a third series of experiments, we used more realistic images of natural landscapes as background contexts to establish the robustness of the contextual cueing effect as well as its ecological relevance claimed by Chun and colleagues. We furthermore added a second task to these experiments to study whether the acquired knowledge about the background-target location associations would (automatically) transfer to another visual search task, namely a change detection task. If participants have learned that certain locations of the repeated images are “important”, since they contain the target item to look for, then changes occurring at those specific locations should lead to less “change blindness” than changes occurring at other irrelevant locations. We used two different types of instructions to introduce this second task after the visual search task, where we either stressed the link between the two tasks, i.e., telling them that remembering the “important” locations for each image could be used to find the changes faster, or we simply told them to perform the second task without any reference to the first one. We will close this thesis with a general discussion, combining findings based on our review of the existing research literature and findings based on our own experimental explorations of the contextual cueing effect. By this we will discuss the implications of our empirical studies for the scientific investigation of contextual cueing and implicit learning, in terms of theoretical, empirical and methodological issues. [less ▲]

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See detailHigher Lie and Leibniz algebras
Khudaverdyan, David UL

Doctoral thesis (2013)

Detailed reference viewed: 71 (9 UL)
See detailIl principio di proporzionalità nella disciplina del mandato d'arresto europeo
Marletta, Angelo UL

Doctoral thesis (2013)

This thesis deals with a current issue in the enforcement of the European Arrest Warrant. Surrender procedures were originally «designed with major criminals in mind», but in an increasing number of cases ... [more ▼]

This thesis deals with a current issue in the enforcement of the European Arrest Warrant. Surrender procedures were originally «designed with major criminals in mind», but in an increasing number of cases they involved minor offences and “trivial cases”. This has caused a great concern about keeping the mutual trust in the Area of freedom, security and justice. In 2011 a Report of the European Commission stressed the importance of the respect of proportionality principle in this highly sensitive field of EU law. This essay analyzes the possibility of applying the proportionality check to the European Arrest Warrant in a fundamental rights perspective. Specific attention is paid to the European Charter of Fundamental Rights and to the Art. 52 par. 1, as a binding constitutional norm establishing the proportionality principle for the whole EU legal order. [less ▲]

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See detailEntwicklungskindheit als Beobachtungsprojekt. Ethnographische Studien zu den Praktiken der Entwicklungsbeobachtung in kindermedizinischen Untersuchungen
Bollig, Sabine UL

Doctoral thesis (2013)

Diese publikationsbasierte Dissertationsschrift bündelt neun bereits veröffentlichte ethnographische und methodologische Studien zu den Praktiken der entwicklungsbezogenen Beobachtung von Kindern in ... [more ▼]

Diese publikationsbasierte Dissertationsschrift bündelt neun bereits veröffentlichte ethnographische und methodologische Studien zu den Praktiken der entwicklungsbezogenen Beobachtung von Kindern in Kindervorsorge‐ und Schuleingangsuntersuchungen. Den gemeinsamen Bezugspunkt finden die vorgelegten Studien in der Frage, wie in diesen medizinischen Beobachtungspraxen ‚Entwicklungskindheit‘ formiert wird. Unter ‚Entwicklungskindheit’ wird eine über das Entwicklungskonzept aufgespannte Konfigurierung von Kindheit gefasst, die nicht nur bestimmte Bilder von Kindern erzeugt, sondern auch die Unterscheidung zwischen Kindern und Erwachsenen bzw. Kindern und ihren Eltern normiert und relational reguliert. Insofern ist die ‚Entwicklungskindheit‘ als eine epistemische wie praktische Form ‚generationalen Ordnens‘ zu verstehen. An der Schnittstelle von erziehungswissenschaftlicher Kindheitsforschung, Medizin‐ und Präventionssoziologie wird mit diesem Bezugspunkt dann sowohl die Frage formulierbar, wie im Vollzug der Kindervorsorge‐ und Schuleingangsuntersuchungen deren ‚einheimischen‘ Entwicklungskonzepte ‚praktiziert‘ werden, als auch wie in diese Darstellungspraxis Ansatzpunkte für die ‚pädagogische Ordnung der Familie‘ eingewoben sind.Auf einer methodologischen Ebene wurde dieses Forschungsprogramm über einen praxistheoretische Modellierung der ‚Praktiken der Entwicklungsbeobachtung‘ konzeptualisiert und mit den Methoden der praxisanalytisch ausgerichteten Ethnographie realisiert. Gegenstandstheoretisch werden über die verschiedenen empirischen Studien hinweg vier Dimensionen dieser Praktiken der Entwicklungsbeobachtung ausdifferenziert: Beobachterkollektive, Beobachteroptionen, Beobachterprogramme und Beobachtungsbühnen. Die ethnographischen Studien zeigen auf, das im Vollzug der Kindervorsorge‐ und Schuleingangsuntersuchungen ‚Entwicklung‘ in dreifacher Weise als ein hybrides Beobachtungsobjekt konstituiert wird: erstens, da sich in den verteilten Praktiken der Entwicklungsbeobachtung sehr heterogene ‚Partizipanden‘ der entwicklungsdiagnostischen Praxis kollektivieren um Entwicklung als zeitlichen, sozialen, biologischen und räumlichen Prozess sichtbar zu mache und als ‚normale‘ oder ‚abweichende‘ Entwicklung beurteilen zu können. ‚Hybrid‘ auch zweitens, weil das Beobachtungsobjekt ‚Entwicklung‘ zwar an Kindern erarbeitet wird, gleichzeitig aber auch die Eltern und die Familie als Bedingungskontext und Bearbeitungsressource für Entwicklung in dieses Beobachtungsobjekt eingewoben werden. Dieses Beobachtungsobjekt ‚Entwicklung‘ ist, drittens, aber auch als hybrid zu bestimmen, weil es in den beiden Beobachtungsformaten Kindervorsorgen und Schuleingangsuntersuchungen, je spezifisch hervorgebracht wird, diese ‚einheimischen Entwicklungskonzepte‘ jedoch verschiedene Kontexte (Familie, Schule, Kita, etc.) miteinander vermitteln und in Form von weiteren Beobachtungsaufgaben auch in diese hinein reichen. Insofern ist das hybride Beobachtungsobjekt ‚Entwicklung‘ auch nicht einfach nur ein medizinisches Objekt, vielmehr ist es durch einen Verschnitt von medizinischen und pädagogischen Wissens‐ und Praxisformen aufgebaut. Mit Blick auf internationale Forschungsarbeiten, die herausarbeiten, dass die gesellschaftliche Konfigurierung der spätmodernen Familie maßgeblich über eine wissensbasierte Konzeption kompetenter Elternschaft aufgebaut ist, zeigen die hier eingereichten Studien auf, dass dieses erforderliche elterliche Wissen im praktischen Vollzug der Kindervorsorge‐und Schuleingangsuntersuchungen maßgeblich als Beobachtungswissen eingefordert und stimuliert wird. Und zwar sowohl mit Blick auf eine fortlaufende Entwicklungsbeobachtung der Kinder durch ihre Eltern, der Koordinierung von professionellen wie privaten Beobachtungspraxen zwischen Eltern und Professionellen, als auch über die Selbstbeobachtung der Eltern von sich selbst als Eltern. In den Kindervorsorge‐ und Schuleingangsuntersuchungen ‚materialisiert‘ sich die Entwicklung von Kindern somit als ein Beobachtungsprojekt, das nicht nur immer weitere Beobachtungen der kindlichen Entwicklung als notwendig erscheinen lässt, sondern in diese Konzeptualisierung von ‚Entwicklungskindheit‘ die Beobachtungskompetenz der Eltern als maßgebliches Kriterium für eine optimale Entwicklung einschreibt. Ihren ‚spätmodernen Charakter’ entfalten die Untersuchungen indem sie die Entwicklung der Kinder immanent als ‚riskant‘ entwerfen, womit der Projektcharakter der modernen Kindheitsidee sich gleichermaßen perpetuiert wie transformiert: als ein Projekt der Vervollkommnung, das sich darüber selbst plausibilisiert, dass es über seine ‚Kerntechnologie‘ der kontinuierlichen, präventiven Entwicklungsbeobachtung der Kinder, nicht nur deren Status als prekär definiert, sondern auch den ihrer Eltern. Neben diesen auf die Formierung von ‚Entwicklungskindheit‘ bezogenen empirischen Studien versammelt das Konvolut aber auch Studien, die sich zum einen mit methodologischen und methodischen Fragestellungen ethnographischen Forschens beschäftigen und zum anderen, das in dieser Dissertation entwickelte Modell der ‚verteilten Praktiken der Entwicklungsbeobachtung‘ auf einen weiteren zentralen Kontext der Dauerbeobachtung von Kindern beziehen, die fortlaufende Beobachtung kindlicher Entwicklungs‐ und Bildungsprozesse in Kindertageseinrichtungen. [less ▲]

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See detailEfficient Communication Protocols for ad hoc Networks
Ruiz Villalobos, Gracia Patricia UL

Doctoral thesis (2013)

Mobile ad hoc networks, also called MANETs, are self-organised networks spontaneously created between neighbouring devices that do not need any infrastructure. The possibility of deploying a communication ... [more ▼]

Mobile ad hoc networks, also called MANETs, are self-organised networks spontaneously created between neighbouring devices that do not need any infrastructure. The possibility of deploying a communication network at any moment and at any place opens a wide range of potential scenarios where the use of an ad hoc network is extremely important and useful. For example, we can imagine an area with no infrastructure, due to a natural disaster (flooding, earthquake, etc.), a war damage or simply a remote location. In such situations, the deployment of an ad hoc network for rescuing or evacuating people is key. %Allowing the communication between groups located in distant areas may be very helpful in critical situations in order to coordinate and reorganise them. However, ad hoc networks are not restricted to safety of disaster situations, they can also be used for gathering sensed data and send it to a remote server, exchanging safety road messages between vehicles or simply for infotainment, etc. Efficient communication protocols are very important for providing good services, but in ad hoc networks is very challenging. It is necessary to deal with packet loss, collisions, mobility, network partitions, fading, energy constraints, obstacles, etc. Due to the intrinsic broadcast nature of wireless medium, dissemination algorithms are one of the most appropriate protocols for communicating devices. Additionally, broadcasting is one of the main low level operation as many applications and even other protocols rely on its service. Therefore, in this thesis, we are proposing two different broadcasting algorithms for efficiently disseminate messages in the network. The first approach relays on an underlying tree topology, while the second is an energy aware algorithm that tries to reduce the energy consumption. In these unpredictable and changeable networks, protocols need to adapt to the current circumstances and this adaptability is usually obtained using thresholds. The values of these thresholds directly influence the behaviour of the algorithm. Finding them is a complex and critical task as protocols are usually very sensitive. We tackle this problem using approximation algorithms or metaheuristics, more specifically, we use a parallel iterative local search and two evolutionary algorithms. In order to ease this process, we have created a modular experimental framework for evaluating, validating and optimising any algorithm in MANETs. [less ▲]

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See detailErmüdungseigenschaften des Wabenkerns von sandwichpaneelen aus Aluminium
Wahl, Laurent UL

Doctoral thesis (2013)

In comparison to their weight, honeycomb composite structures have a high bending stiffness, which makes them very suited for every application where little weight is important, like airplanes, railway ... [more ▼]

In comparison to their weight, honeycomb composite structures have a high bending stiffness, which makes them very suited for every application where little weight is important, like airplanes, railway-cars and vehicles. These structures are subjected to cyclic loading. The sandwich panels consist of two thin and stiff aluminium face sheets, which are bonded to a thick and lightweight aluminium honeycomb core. The shear stresses in the core of these structures depend strongly on the angle of the load application, because the core is not homogeneous. The distribution and the level of the shear stresses are investigated using analytical calculations. The load direction which induces highest stresses in the honeycomb core is derived. This direction is not the W-direction, which is the most compliant one. In literature, there are few fatigue properties of the honeycomb core described. The fatigue properties of the core are investigated in this work using the finite element method and experiments. The experimental investigations consist of three-point bending tests, pulsating roller tests, Food-Cart Roller tests and several tests on real components. Depending on the load application, the honeycomb core fails either through core indentation or shear failure. Several fatigue tests were carried out at constant load amplitude and the failure mode is investigated. The sandwich structures were modeled with the ANSYS finite element software. The number of elements is reduced by replacing the honeycomb core with a homogeneous core with orthotropic properties. In order to get the stresses in the honeycomb core at the critical location, a submodel was created. In this work, some equations are derived in order to calculate the real shear stresses from the shear stresses of the homogeneous core. In addition, imperfections are included in the model. Furthermore, buckling analyses were used to examine core indentation failure. Based on these simulations, both failure modes described above can be explained. Core indentation occurs, when the honeycomb cells are buckling due to the load application. The buckling of the cells can be avoided by using a smoother load application. In this case, the core fails in the three-point bending test by shear failure. The fatigue life of the examined specimens is successfully approximated in this manuscript, with the lifetime analysis being based on the FKM-guideline. Every simulation is validated by experimental results. [less ▲]

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See detailStabilität wechselrichtergeführter Inselnetze
Jostock, Markus UL

Doctoral thesis (2013)

The PhD thesis develops a control model for island grids, where voltage source inverters with droop control adapt frequency and voltage amplitude and no classic rotating generators are present. The ... [more ▼]

The PhD thesis develops a control model for island grids, where voltage source inverters with droop control adapt frequency and voltage amplitude and no classic rotating generators are present. The presented linear, time invariant model is based on a state space control model of inverters and linearised power flow equations for the grid lines, the grid topology is captured in a node incidence matrix. Such a compound model for inverter driven island grids has not yet been developed to the author’s knowledge. Most existing models have been formulated for very small grids or inverter constellations. The presented control model allows to investigate grids with a very high number of inverters and with arbitrary grid structures and facilitates the calculation of the compound state space model and the MIMO transfer function matrix. No explicit re-formulation of the differential equations is necessary for different grid topologies, as this information is captured in the node incidence matrix. The thesis further investigates the stability of inverter driven island grids, i.e. power grids decoupled from the interconnected European power grid and in which most of the primary sources are renewable energy sources, injected via voltage source inverters. As inverters do not have rotating masses and thus no rotational inertia, they can be actuated much faster than classical synchronous generators. The effect of this property on the overall system stability is investigated in this work. The grid frequency is considered as a distributed parameter, where during transient phases, each grid node has its own valid phase angle speed. During transient phases, the inverters adjust injection frequency according to their droop, due to a local active power change. Until all inverters have adapted their injection frequencies, in each grid node a separate phase speed is valid. This behaviour could be verified with laboratory experiments and is integrated into the formal model with a graph theory approach. The power flow through grid lines due to voltage changes is a physical effect and practically immediate, while the adaptation of voltage amplitude and frequency through the inverters is a slower action depending on the inverter control algorithm. The separate modelling of inverters with their droop control on the one hand and the passive grid structure with the load flows on the other hand is justified by singular perturbation. An inverter driven island grid in droop mode can become unstable. Different parameters of the model have an influence on the system stability. A stability analysis is performed on simple grid structures as line, ring and lattice structure based on pole-zero plots. The influence of single parameters on the pole positions is investigated. Three pole regions appear for the compound model, their position and form is depending on the model parameters. For the model of the inverter two time constants are assumed: the smaller time constant Tm models the physically minimal possible delay in a PT1 element, while the larger time constant TWR can be adjusted arbitrarily by programming in an inverter. Both time constants determine more or less the position and form of one pole region each. If both time constants approach each other, conjugate complex poles appear. For large values of TWR the system can become unstable as poles move into the right half pane. This thesis reaches the following conclusions: Small rated power values of the inverters lead to potential instability as small power perturbations may cause large frequency changes. Since this effect is related to the value of the time constants, a stabilising effect can be observed when the time constants of the inverters are minimised, which enables the inverters to react more quickly to the frequency changes. An increasing number of inverters in the grid increases the system order and thus the number of poles. Under unfavourable conditions these poles may be badly damped and may develop into dominant complex conjugate poles. Similar effects can be observed for short grid lines: in systems with short grid connections, the inverters have a stronger electric coupling, bringing forward dominant pole pairs. The control of voltage and frequency by droops has been developed for in- ductive high voltage grids. In low voltage grids with ohmic line characteristics the droops lead to cross coupling between the voltage and frequency controller, causing an additional voltage reaction due to an active power change and an additional frequency reaction due to a reactive power change. This effect can be counteracted by the rotation of the measured P and Q coordinates in the droop control. The rotation angle is strongly related to the impedance angle at the point of connection of the inverter. Using P/Q rotation reduces the number of dominant pole pairs and fosters the integration of higher numbers of inverters without reaching the stability limits of the grid. Based on the laboratory results, a method for detection of the optimal P/Q rotation angle has been filed for patent. [less ▲]

Detailed reference viewed: 349 (17 UL)
See detailCrystallization in hard sphere systems
Radu, Marc UL

Doctoral thesis (2013)

Detailed reference viewed: 129 (15 UL)
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See detailSocially Augmented Content Distribution in Hybrid Networks
Klasen, Bernd UL

Doctoral thesis (2013)

Internet traffic is experiencing a great growth whose end cannot be foreseen. Whether it will always be possible to upgrade the infrastructure fast enough to keep up with the increasing demand is ... [more ▼]

Internet traffic is experiencing a great growth whose end cannot be foreseen. Whether it will always be possible to upgrade the infrastructure fast enough to keep up with the increasing demand is uncertain. On any account this undertaking will be expensive and the consequences that arise from the thereby growing complexity are hard to predict. For many files delivered via Internet a large degree of redundancy can be observed. Since such transfers use unicast transmission mode, the induced traffic increases linearly with the number of downloads. This is a challenge for the delivery network used and for the servers. This thesis argues that the peaks in Internet traffic can be truncated and the aggregated amount of bytes transferred be significantly reduced by shifting this redundant traffic to a broadcast network. Thereby the unicast and broadcast network are combined by means of a hybrid network that allows dynamic routing of data via either of them. Based on this infrastructure a socially augmented content distribution model relying on P2P technology is defined that manages the network selection and the delivery of data. It aims at delivering files to user caches prior to the demand and thus can level out the fluctuations in Internet and server load. Thereby it makes use of social networks by means of capitalizing information about social ties, similarities and mutual influence among individuals. It is shown that by this approach the Internet traffic can be significantly reduced while only requiring a comparatively small amount of broadcast network capacity. At the same time the user perceived quality of service is increased by means of a reduced delivery time. [less ▲]

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See detailAn Investigation of Number-Space Associations: Exploring Developmental and Cognitive Influences
Hoffmann, Danielle UL

Doctoral thesis (2013)

In order to comprehend higher order arithmetic it is of crucial importance to get a thorough understanding of basic number processes. One of the basic characteristics of numerical representations is its ... [more ▼]

In order to comprehend higher order arithmetic it is of crucial importance to get a thorough understanding of basic number processes. One of the basic characteristics of numerical representations is its association to space. Empirical evidence for the number-space association is the SNARC effect (Spatial Numerical Associations of Response Codes, Dehaene et al., 1993): in binary classification judgments participants are faster responding to small/large digits on the left/right response side respectively. However, only 65-75% of participants display this signature effect of number-space associations (Wood et al., 2006a; 2006b). Although some influencing factors on the SNARC effect such as response speed and writing habits (Gevers et al., 2006; Shaki et al., 2009) have been identified, research on this issue remains scarce. Another question mark in the number-space research is the ontogenetic emergence and evolution of the numerical-spatial relationship. The present work gives a brief overview of what is known about the number-space association and adds empirical data to existing scientific knowledge. Specifically we found that number-space associations in the form of a SNARC effect emerge early in life (from age 5.5) and that its relationship to basic number knowledge at that age depends on the task at hand. Moreover, in adults, arithmetic proficiency, as well as interference inhibition capacities are related to the strength of the SNARC effect. A very strong relationship exists between the strength of the SNARC effect and chronological age, as the SNARC effect becomes stronger with increasing age. [less ▲]

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See detailStrukturen, Engagement und Motivation bei LAN-Gaming, Techno und Parkour. Eine qualitative Studie in jugendkulturellen Szene-Eliten in Luxemburg
Zeimet, Jean-Claude UL

Doctoral thesis (2013)

Politics and research in Luxembourg pay little attention to the local youth(sub)cultures despite their manifold activities and high visibility. In youth research und youth studies youth(sub)cultures were ... [more ▼]

Politics and research in Luxembourg pay little attention to the local youth(sub)cultures despite their manifold activities and high visibility. In youth research und youth studies youth(sub)cultures were mainly perceived in connection with leisure activities and delinquent behaviour but have never been a topic of their own. The present dissertation expands the existing data and supplements youth research in Luxembourg by adding a further and important element. It allows a first empirical view on Luxembourgish youth(sub)cultures and their scenes. The study is based on a field research project following a qualitative heuristic design (Kleining, 1982) and focussing on three youth(sub)cultures: LAN-gaming, Techno and Parkour. All collected data was subject to a computer aided data analysis on commonalities for the different research topics. Two research questions emerging from the field study were of main interest. The primarily focus is on the structure of the youth(sub)cultures, the way they are conceived and constituted. Knowledge of the structure is regarded as an essential and important starting point to understand youth(sub)cultures. The structure's analysis is led by the 'scene concept' by Hitzler and Niederbacher (2010b). It could be demonstrated, that the explored youth(sub)cultures can be considered as scenes in terms of the 'scene concept'. However, the analysis shows some further characteristics, e.g. requirements to join the scene, and the scene's way to deal with preconceptions. Scenes in Luxembourg seem to show tendencies to break with their informal structure and apparently approach more traditional and formal ways of association. Youth(sub)cultures seem to face some elementary changes and developments in the future. Identifying the framework of the three scenes allowed elaborating an appropriate and meaningful thematic depth. Already at an early stage of the field research it became apparent that few scene members invest considerable time and energy to create and establish the scene. By doing so they are practically also in charge of the scene's structure. According to the 'scene concept' these people could be described as organisational elite – the scene's motor. Using methods of the free field research concept (Girtler, 2001) the study asked for the motives lying behind this commitment by asking: What lies behind the fun? So the second research topic targeted first these members' commitment and could identify decision levels with assigned roles and fields of activity, e.g. the administrator, the organiser or the expert. The organisational elite's commitment shows two different stages of motives; motives to start and motives to continue the work. The Maynooth-model was developed to illustrate the findings of this research. It shows the interaction and the circuit of the members' motives and influencing framework factors. There is a rather enclosed and complex interaction system, which provides room and questions for further research within the field. There’s a lot more than fun to make a scene happen and work [less ▲]

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See detailDisplacement and Resettlement: The Livelihoods of Resettlers and Hosts Displacement and Resettlement: The Livelihoods of Resettlers and Hosts
Wayessa, Gutu Olana UL

Doctoral thesis (2013)

The study focuses on population displacement and the livelihood implications of state-planned resettlement schemes that have been implemented in Western Oromia, Ethiopia. It addresses the livelihoods of ... [more ▼]

The study focuses on population displacement and the livelihood implications of state-planned resettlement schemes that have been implemented in Western Oromia, Ethiopia. It addresses the livelihoods of both the resettlers and the hosts. Although such resettlements have been implemented in the country since the 1960s, this study addresses those carried out since 2003. The broad objective of the study was to explore the dynamics of displacement and resettlement, and their impacts on the livelihoods of resettler and host populations. The specific objectives were: (1) to assess the policies and practices of the resettlement program carried out during the tenure of the current government; (2) to analyze the livelihood outcomes of the resettlements for resettlers and hosts in terms of changes in access to livelihood resources and social services; and (3) to examine resettlers’ and hosts’ perceptions of and attitudes towards the resettlement program. The theory of impoverishment risks and livelihood reconstruction (IRLR), the sustainable livelihood framework (SLF), and political ecology constitute the pillars of the theoretical framework. Primary data were collected in 2009 through a survey of 630 households in eight resettlement sites, and 68 thematic (group and individual) interviews in 13 resettlement sites. Several interviews were also held with government officials. Households were selected for the survey through stratified random sampling, whereas informants were selected for the interviews purposively. The primary data were complemented with relevant secondary data. The study is interdisciplinary, and combines both qualitative and quantitative methods through a concurrent mixed-methods design. Qualitative methods were used to address how and why questions through thematic analysis of the interviews and policy documents, thereby illuminating the substantive significance of the issues at stake. Quantitative methods were employed to quantify changes and establish the statistical significance of variables of interest. The quantitative methods used include descriptive statistics, such as percentages, means and cross-tabulations, and inferential statistics, such as logistic regression, mean comparisons using non-parametric tests, factor analysis, Chi-square tests, and loglinear analysis. The complementary relation between the two methods has proved useful in understanding and explaining the processes and the outcomes of the resettlement scheme. The research illuminates the causes, the processes, and the outcomes of the current resettlement program in particular, and critically analyzes the assumptions underlying the resettlement policies of the current and the previous regimes in general. Multiple causes and assumptions underlay the resettlement scheme, most notably land and rainfall shortages in resettlers’ areas of origin, and the government’s claim of land abundance. This last assumption has been persistently made by regime after regime, despite empirical counter-evidence, as also shown in this study. By revealing that the scheme resulted in the displacement of the host population to make way for resettlement, that the resettlers were given less land than promised, and that the relocation led to serious conflicts and disputes over land between resettlers and hosts, the study challenges the state’s supposition and rhetoric of “ample land.” The evidence also illuminates the relocation’s glaring lack of inclusiveness of both resettlers and hosts, despite the benign principles of “voluntarism” and “consultation.” The outcomes were multiple, leaving some better-off, others worse-off, and still others with no noticeable livelihood deterioration or improvement. In cases where old problems were alleviated, new ones emerged in a context of little plan and capacity to meet contingencies. This calls into question government propagation of generalized “success” in the resettlement scheme. Although little is known about the sustainability of the improved outcomes for some resettlers in some resettlement sites, the evidence from this study also counteracts the depiction of the scheme as a general “failure.” The findings suggest that the relative importance of the risks experienced by the resettlers and the hosts varied between the two population groups, and among different resettlement sites. The resettlement sites were widely differentiated in terms of biophysical factors, notably soil fertility and the availability of grazing land. This has serious implications for the resettlers and the hosts as their livelihoods are almost entirely based on agricultural activities. Moreover, historical issues, wider socio-political structures, physical infrastructure, and resettler-host relations are crucial for the understanding of how people’s access to livelihood resources and social services is shaped. However, resettler-host relations should be seen in a broader context of state-society relations, as the state is a key actor in planning and implementing the resettlement programs. An important policy lesson from this study is that when one focuses on certain livelihood aspects, one also needs to be aware that other potential livelihood components not evident today may become vital in the future. This awareness should motivate adaptive planning and management to meet contingencies in a way that reflects the multifaceted nature of livelihoods. [less ▲]

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See detailRegulation of microRNA Expression by STAT1 Transcription Factors - Relevance for Melanoma Development
Schmitt, Martina UL

Doctoral thesis (2013)

The type-II-cytokine IFN-γ (interferon gamma) is not only a pivotal player in innate immune responses but also assumes functions in controlling tumor cell growth by orchestrating cellular responses ... [more ▼]

The type-II-cytokine IFN-γ (interferon gamma) is not only a pivotal player in innate immune responses but also assumes functions in controlling tumor cell growth by orchestrating cellular responses against neoplastic cells. It predominantly triggers cellular responses through the Janus Kinase (Jak)/ Signal Transducer and Activator of Transcription 1 (STAT1) pathway leading to STAT1 binding to the promoter region of target genes. As key regulators of mRNA and protein expression levels, microRNAs (small non-coding RNAs) take part in fine-tuning complex biological processes such as cell proliferation, neoplastic transformation, apoptosis, immune surveillance and differentiation. MiR-29, one of the most interesting miRNA families in humans to date, consists of three mature members miR-29a, miR-29b and miR-29c, which are encoded in two genetic clusters. In this PhD thesis, the miR-29 primary cluster pri-29a~b-1 was shown to be IFN-γ-induced and STAT1-dependently up-regulated in melanoma cell lines. Furthermore, expression levels of mature miR-29a and miR-29b were elevated in cell lines and in primary melanoma patient samples while the pri-29b-2~c cluster was almost undetectable in cell lines. Moreover, tumor-suppressing properties of miR-29 family members have been detected: inhibition of melanoma cell proliferation could be induced by miR-29a, which down-regulated CDK6 (cyclin-dependent kinase 6), an important player in cell cycle G1/S transition. Also, knockdown of CDK6 resulted in reduced proliferation of melanoma cells, suggesting that miR-29-mediated growth inhibitory effects may be brought about by CDK6-downregulation. These findings identify the pri-29a~b-1 cluster as a novel IFN-γ-regulated gene. Furthermore, a potential novel signaling pathway was identified: IFN-γ  Jaks  P-STAT1  miR-29  CDK6, which opens up new connections between miRNAs, interferon signaling and malignant melanoma, possibly clearing the way to novel concepts for new treatment options in the future. [less ▲]

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See detailLa dynamique de la complexité en matière de relations extérieures des Etats membres de l'Union européenne
Lickova, Magdalena UL

Doctoral thesis (2013)

In its capacity of a member of the European Union, the State agrees to submit to a set of rules framing its autonomy in the field of external relations. While this set of rules can be assessed in terms of ... [more ▼]

In its capacity of a member of the European Union, the State agrees to submit to a set of rules framing its autonomy in the field of external relations. While this set of rules can be assessed in terms of categories of legal effects acting unilaterally upon the EU Member State, the present study attempts to go further by examining what we believe to be a dynamic chain of complexity, composed of actions, reactions, and retroactions of the actors involved. During our research, we indeed found that the manner in which the Union affects the EU Member States’ external relations is far from being a one-way process, but rather constitutes permanent and circular dynamics of interaction between what we shall call an integrated Member State and the Union, between the Union and what we shall call a global Member State, and between the respective Member State’s global and integrated faces. The integrated Member State may step aside to let the Union act in its stead, or act in conjunction with the Union, but ʽtaking the back seatʼ in this manner does not engage its global face, its alter ego, which will return to take center stage (if it did not simply stay there to begin with) to complete (or to compete with) the actions of the Union, or even to solicit the Unionʼs support with respect to the relations it established vis-à-vis third parties. As we proceed, we find that the Member State, who initially appeared to be a mere passive object of our research, is in fact an active agent, contributing, whether through retroaction or through the competing exercise of its sovereign competencies, to the face of the Unionʼs external relations. Accordingly, no research into the external relations of the EU can be complete without taking into account the impact of EU law on the integrated Member States, and the impact felt in turn by the EU as the result of the Member Statesʼ global actions. In the same way, such research should consider the impact of international law on the global Member States and the impact felt in turn by international law as a result of the actions of the integrated face of these same Member States [less ▲]

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See detailEssays on Dutch Disease and International Finance
Vermeulen, Wessel UL

Doctoral thesis (2013)

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See detailSuprarégionalisation transfrontalière? Grande Région Saar-Lor-Lux
Evrard, Estelle UL

Doctoral thesis (2013)

European Union integration policy has challenged traditional border functions resulting in regionalisation processes and policy makers facing diverse functional interdependencies across multiple scales ... [more ▼]

European Union integration policy has challenged traditional border functions resulting in regionalisation processes and policy makers facing diverse functional interdependencies across multiple scales and territories. Local and regional authorities participate in a European multi-level governance system. Within regions, cross-border cooperation institutionalises distinct forms of governance. This thesis investigates the regionalisation process launched across borders at a subnational level using the case study of the Greater Region Saar-Lor-Lux. Conceptually, this study defines regionalization as construction of a region. This analysis of cross-border cooperation in the Greater Region explains “cross-border supraregionalisation” through three processes. First, the discursive construction of a cross-border strategy illustrates the complexity of joint positioning. The metropolitan impetus advocated in the Greater Region reveals the ambivalent objectives of the partners and the dominance of the metropolitan discourse at the national and European level. Second, beyond the institutional cooperation space (“Vertragraum”), the space of the mandate (“Mandatsraum”) serves as a medium to territorialise the joint strategy. It results from the ideal projection of the strategy in space and thus, evokes a bordering process. This “soft space” is constantly negotiated between the partners and illustrates patterns of cross-border spatial empowerment. Third, the study analyses the extent to which cross-border partners delegate responsibilities and legitimacy to joint cross-border institutions, especially through the innovative legal instrument European Grouping for Territorial Cooperation. [less ▲]

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See detailWas bleibt… Literarische Zeugenschaft im Kontext des Holocaust
Wehming, Marie-Christine UL

Doctoral thesis (2013)

Detailed reference viewed: 115 (6 UL)
See detailSystems Engineering, Systems Thinking, and Learning: a Case Study in Space Industry
Moser, Hubert UL

Doctoral thesis (2013)

Systems thinking is a prerequisite of systems engineering, which is performed in multi-disciplinary teams, i.e. software engineers, mechanical engineers, electronic engineers, and others, work together to ... [more ▼]

Systems thinking is a prerequisite of systems engineering, which is performed in multi-disciplinary teams, i.e. software engineers, mechanical engineers, electronic engineers, and others, work together to develop, build, and test technical systems such as space systems. The more team members consider a systems perspective the less rework is expected and the less effort of systems engineers is required. How systems thinking evolves in practice is not sufficiently understood. Therefore, work activity of multi-disciplinary teams has been studied in an empirical study. Data from multiple sources and of different temporal resolution has been collected over four years in four studies in space systems engineering. These studies are a concept exploration project in a summer school, two concept exploration projects in a concurrent design facility, and five projects in several lifecycle stages in a small space systems company. An analytical framework has been developed based on an activity-theoretical analysis and a theme-and-key-event analysis. Contradicting multiple roles, differences in parameter definition and impact, differences in work approaches and ways of interacting, contradicting work standards, trust and doubts in extra-disciplinary decisions, awareness of diversity and orientation towards extra-disciplinary interactors, and velocity and availability of information are identified contradictions with learning potential. These contradictions provoke initiators of multi-disciplinary interaction. These are proactive provision of extra-disciplinary advice and three types of questions: critical questioning across disciplinary boundaries, asking for extra-disciplinary advice, and questioning the current work approach. The contradictions prompt the selection of themes that comprise several key events. These themes and key events are analysed on three levels (macro, meso, and micro) with a focus on systems thinking content and discourse features. Systems thinking evolves in interaction within a broad temporal range, from minutes to years. It evolves vertically, i.e. within a discipline, and horizontally, i.e. across disciplines. The evolution of systems thinking is influenced by the multi-disciplinary quality of interaction. This quality is defined by the diversity or multi-disciplinarity of the interaction, the awareness of the diversity, the orientation towards extra-disciplinary interactors, the differences in interactional responsiveness, and the cohesion of interaction. Improving the multi-disciplinary quality of interaction to foster the evolution of systems thinking is the major goal of the developed WAVES (Work Activity for a Versatile Evolution of Systems engineering and thinking) strategy. The WAVES strategy comprises two paths. The first path focuses on the introduction of employees into professional life, (space) industry, a company, a team, and a task. The second path focuses on the continuous improvement of the work activity. The implementation and evaluation of WAVES in a small space system company is the basic contribution to industry. The implementation within systems engineering departments of large space organisations has been prepared. The developed analytical framework contributes a new approach to analyse work activity in practice. Finally, the answers to the first part of the main research question contribute to a better understanding of systems engineering, systems thinking, and its learning in practice. [less ▲]

Detailed reference viewed: 254 (10 UL)
See detailResearch on DNA sequence assembly using graph approach
Gawron, Piotr UL

Doctoral thesis (2013)

Detailed reference viewed: 125 (18 UL)
See detailApplications of Combinatorial Optimization for Online Shopping
Musial, Jedrzej UL

Doctoral thesis (2013)

Detailed reference viewed: 62 (2 UL)
See detailDie Flexion der Nominalphrase im Luxemburgischen
Breckler, Christine UL

Doctoral thesis (2013)

Detailed reference viewed: 159 (16 UL)
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See detailMicroarchitectural Side-Channel Attacks
Gallais, Jean-Francois UL

Doctoral thesis (2013)

Cryptanalysis is the science which evaluates the security of a cryptosystem and detects its weaknesses and flaws. Initially confined to the black-box model, where only the input and output data were ... [more ▼]

Cryptanalysis is the science which evaluates the security of a cryptosystem and detects its weaknesses and flaws. Initially confined to the black-box model, where only the input and output data were considered, cryptanalysis is now broadened to the security evaluation of the physical implementation of a cryptosystem. The implementation attacks which compose physical cryptanalysis are divided into fault attacks, exploiting the effect of disruption of the normal functioning of the device, and side-channel attacks, exploiting the dependency between the instructions and data (including key bits) processed by a device and its physical characteristics (e.g. execution time, power consumption, electromagnetic (EM) radiations). In the scope of this thesis, we particularly focus on the latter attacks. “Every computation leaks information” and lowering the physical leakages of an implementation is indeed a complex task both from cryptographic and engineering viewpoints, especially when performance and cost enter the equation. The development of adequate countermeasures necessitates a thorough knowledge of the various vulnerabilities that the microcontroller induces. Although generic side-channel attacks such as Differential Power Analysis (DPA) can generally retrieve the key with weak assumptions on a cryptographic implementation, we show in this thesis that the focus on specific components and properties from the architecture of the target device may allow an adversary to yield better success in a key recovery and sometimes to thwart DPA countermeasures. First, we elaborate on attacks which deduce the cache activity of a device from single side-channel traces and algebraically exploit this information to recover the key. We propose different attacks against embedded software implementations of the Advanced Encryption Standard (AES) in the chosen- and known-plaintext scenarios and make them tolerant to environments where high noise or a partially preloaded cache would normally introduce errors in the key recovery. Second, we discuss the failure of standard DPA against the modular addition and propose a practical and generic approach to circumvent it. Third, we show that microarchitectural leakages and fault inductions can be exploited in a constructive way when induced by hardware Trojans implemented on general-purpose microprocessors. Such Trojans can either provide an adversary with a backdoor access to the trojanized device executing an arbitrary cryptographic software or serve to protect the Intellectual Property (IP) of the chip designer through digital watermarking. The last part concerns divide and conquer side-channel attacks such as DPA. Testing different combinations of key chunk candidates turns out to be very complex when the individual chunk recoveries are bounded in measurement complexity or performed in noisy environments. We address the so-called key enumeration problem with an efficient sorting method. [less ▲]

Detailed reference viewed: 139 (6 UL)
See detailOn Intersection Codes and Iterative Decoding
Franck, Christian UL

Doctoral thesis (2013)

Detailed reference viewed: 142 (26 UL)