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See detailContribution à la résolution de la conjecture S-adique
Leroy, Julien UL

Doctoral thesis (2012)

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See detailSocial network analysis over dynamic graphs and application to urban mobile ad hoc networks
Herbiet, Guillaume-Jean UL

Doctoral thesis (2012)

Wireless mobile ad hoc networks (MANET) are composed of mobile communicating devices that self-organize to ubiquitously exchange information over the air. Envisioned applications for such networks cover ... [more ▼]

Wireless mobile ad hoc networks (MANET) are composed of mobile communicating devices that self-organize to ubiquitously exchange information over the air. Envisioned applications for such networks cover disaster relief situations, battlefield deployment and more generally any use-case that makes the deployment of wired or infrastructure-based networks too costly or simply unsuitable. Lately, new applications for MANETs are developing in the urban environment, namely mobile social networks and vehicular ad hoc networks. Despite this large spectrum of possible applications and the large number of wireless-capable devices available today, mobile ad hoc networks remain confidential. One important reason is the lack of reliability of wireless communications, especially on long path. In this thesis, we propose to cope with this problem by creating virtual structures that will group together limited set of users that are densely and reliably connected in order to favor the dynamic and robust exchange of information. Our proposal uses the concept of community, that first appeared in social network analysis. After reviewing the main concepts taken from this branch of graph theory and justifying the application by underlining the specificities of MANETs in the urban context, we formally present our contribution, based on epidemic propagation of community labels. Then we exhibit its applications on concrete communication systems and how it can benefit more generally to improve the management of wireless ad hoc networks topology. [less ▲]

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See detailBuild Operate and Transfer (BOT) Projects - Contribution à l’étude juridique d’une modalité de partenariat public-privé à la lumière de l'approche Law and Economics
Tatofie, Roger UL

Doctoral thesis (2012)

Infrastructures and utility services are fundamental to economic and human development. Therefore, investment in these areas is critical to economic growth, quality of life, poverty reduction, access to ... [more ▼]

Infrastructures and utility services are fundamental to economic and human development. Therefore, investment in these areas is critical to economic growth, quality of life, poverty reduction, access to education and health care and achieving many of the objectives of a robust economy. Yet, whereas the public sector provides the vast majority of financing for infrastructure services, investments have not matched demand, public funds or borrowings are insufficient and governments are seeking methods to improve the efficient procurement of infrastructure services. Private sector participation in public projects is increasingly becoming a reliable source of investment and, as far as public policies are concerned, an unavoidable feature of our contemporary society even in “core public policies” (for example, greater responsibility for financial planning and welfare provision is being increasingly shifted by the states to the private sector and individuals). In the area of infrastructures and utility services, Public-Private Partnerships (PPP), despite some of their challenging features, are one of the tools in a policy maker’s arsenal which help to increase investment in infrastructure services and improve its efficiency. One of the main advantages of PPP is that, unlike privatization, the government retains strategic control over the project and the ownership of its assets. PPP offers multiple options or structures. As shown in this study, Build, Operate and Transfer (BOT) Projects are one of the numerous options offered by PPP. In a BOT project, a private entity is given the right to design, finance, build and operate for a defined period (“concession period”) a facility that would normally be built by the government. The operation of the project generates revenues and the private entity uses these revenues to service debt and provide the investors with a return. At the end of the defined period, the private entity turns over the facility to the government. In practice, a number of parties - each with sometimes different interests, levels of sophistication and available resources - will be involved in a BOT project: the grantor/host government, the sponsors (generally throughout the project company), the lenders and the contractors (construction contractor, operator, offtake purchaser, input supplier) and the BOT approach can be used for different and various projects (power generation, water treatment, airports, roads, tunnels, bridges…) and, hence, has many variants such as BOO (Build, Own and Operate), BOOT (Build, Own, Operate and Transfer), BTO (Build, Transfer and Operate) etc. The BOT approach is not, however, a panacea for the host government and may involve some disadvantages. In effect, BOT projects are highly complex (from both financial and legal points of view), commercially driven projects, requiring extensive documentation and negotiation and a suitable political, legal, regulatory and economic environment. Nevertheless, it has many potential advantages and still is a viable alternative in most countries to the more traditional approach to public projects. For policy makers, practitioners, investors and, above all, the targeted populations to fully benefit from these advantages, the BOT concept must however be clarified and lifted from the fuzziness in which it has been plunged by commentators. There has actually been a dual view of the BOT concept: On one hand, some commentators consider the BOT concept as a simple public procurement modality, comparable to the concession model, and hence to be subjected to classical public law concepts, practices and requirements such as the public services, public ownership and standards and rules of public budget and accountancy. On the other hand, some other commentators view the BOT concept as a modality of project financing which should therefore be subjected to the requirements of profitability and risks sharing. However, if this dual view presents the BOT concept under two specialized lenses and tends to protect certain interests - i.e. public interests and private interests - it is in fact non satisfactory conceptually as well as practically. In fact, this dual view describes a unique reality which an economic cooperation characterized by harmony and conflict, change and equilibrium. The ambition and objective of this study is therefore to give a full understanding of the BOT concept and to shed light on its originality and its unity. The BOT concept is therefore considered as an economic cooperation device, demonstration made in this study principally under the light of law and economics approach. In effect, structuring a BOT project requires the use of (free) market tools (especially economic and financial tools), which render the law and economic approach perfectly suitable to analyze the BOT concept and reveal its rationality and coherence. Hence, the use of the (strategic) game theory to underline the mutual gains resulting from the cooperation between partners involved in a BOT project; the use of the incomplete contract theory to explain the special care needed to design the BOT contract and its possible adjustments; the use of the theory of the firm and financial contracting to explain the functions of coordination and integration of the project company; or also the use of the public choice theory to analyze the notion of general interest which has led to the conclusion that BOT projects are a combination of public and private interests in order to achieve optimality and mutual gains. More generally however, this study has adopted a pragmatic view, using various and different methods, because analyzing the relationships between State and market requires taking into account a great range of fields, considerations and expertise. This pragmatic approach suggested the study be carried out as a genealogic enterprise, such a process allowing a criticizing stance and a formulation of a new and global theoretical frame presenting the relics and the transformations of the current (dual) views of the BOT concept from which its originality and its unity derive. This study has therefore shown that the contractual, structural, economic and financial interdependence of the BOT project makes it an undeniable economic cooperation device. The BOT concept therefore acquires a conceptual unity which reinforces its functional and practical nature and adds a guarantee of legal security to its use. Besides, it has also been demonstrated that BOT is a signaling and an accountability tool for the partners involved in those operations. Ultimately, as regard to public projects, the BOT concept introduces a bit of rationality in equity and humanity to efficiency. [less ▲]

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See detailSuccess and well-being of young persons in Switzerland
Samuel, Robin UL

Doctoral thesis (2012)

Detailed reference viewed: 137 (12 UL)
See detailVerfahren der Studierendenauswahl für Masterstudiengänge aus Sicht der Bewerber
Herde, Christophe UL

Bachelor/master dissertation (2012)

Detailed reference viewed: 41 (1 UL)
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See detailLe Calcul Quantique
Bernard, Nicolas UL

Bachelor/master dissertation (2012)

Un ordinateur est un objet physique effectuant des opérations logiques, il a donc nécessairement besoin d’un substrat physique pour faire ces opérations. Aussi, si la théorie qui sous-tend l’informatique ... [more ▼]

Un ordinateur est un objet physique effectuant des opérations logiques, il a donc nécessairement besoin d’un substrat physique pour faire ces opérations. Aussi, si la théorie qui sous-tend l’informatique doit beaucoup aux mathématiciens (Turing pour n’en citer qu’un), c’est la physique qui a rendu la réalisation concrète des ordinateurs possible, qu’ils soient réalisés avec des relais électromécaniques, des tubes électroniques ou des transistors. Et cela ne s’arrête pas là : par exemple, d’une part la miniaturisation de ces derniers dans les processeurs fait que les phénomènes quantiques doivent être pris en compte (les électrons risquent de passer d’un fil à un autre par effet tunnel), d’autre part l’accroissement de la vitesse d’horloge rend concrète la barrière qu’est la vitesse de la lumière. Si les ordinateurs ne sont possibles qu’avec une théorie physique suffisamment évoluée, il y a une rétroaction qui se crée, car la physique a beaucoup bénéficié du développement des ordinateurs. Ceux-ci rendent en effet possibles des calculs – d’abord numériques, mais également symboliques – qu’il serait difficile de faire « à la main », pour des questions de temps et « d’erreurs humaines ». Cette possibilité a ouvert la voie à des simulations dans pratiquement toutes les branches de la physique, et ces simulations ont à leur tour pratique- ment créé de nouvelles branches, telle la théorie du chaos. En 1982, Richard Feynman déplorait cependant que les simulations informatiques de processus quantiques ne fussent pas efficaces, et suggérait qu’elles pourraient être bien plus rapides si l’ordinateur était lui-même « quantique » [2]. Dans ce document, nous allons d’abord revenir (chapitre 1) sur ce point et expliquer ce que pourrait faire différemment un ordinateur « quantique ». Nous décrirons ensuite (chapitre 2) les bases théoriques du calcul quantique tel que pourrait le pratiquer un ordinateur de ce type. Nous verrons finalement (chapitre 3) avec l’exemple de l’algorithme de Shor et de la Tranformation de Fourier Quantique qu’au-delà des simulations de processus quantiques, un ordinateur quantique pourrait accélérer dramatiquement d’autres opérations. Nous conclurons sur quelques approches possibles pour la réalisation d’un ordinateur quantique et sur l’existence d’autres applications de la mécanique quantique liées à l’informatique et à la communication qui ne nécessitent pas forcément un tel ordinateur, ainsi que sur des aspects plus philosophiques du calcul quantique. [less ▲]

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See detailReisen zu Pferde im Mittelalter - Semantik und Verwendung des passgehenden Zelter-Reitpferdes
Meiers, Fabienne UL

Bachelor/master dissertation (2012)

Detailed reference viewed: 124 (4 UL)
See detailDesign and Modeling of Privacy-Friendly Reputation
Schiffner, Stefan UL

Doctoral thesis (2012)

Detailed reference viewed: 45 (2 UL)
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See detailViral regulation of nutrient assimilation by algae and prokaryotes
Sheik, Abdul UL

Doctoral thesis (2012)

Detailed reference viewed: 150 (14 UL)
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See detailProactive Dynamic Community of Practice
Dobrican, Remus-Alexandru UL

Bachelor/master dissertation (2012)

The main purpose of this Master Thesis was to invent and design Proactive Scenarios that could help students from the University of Luxembourg to improve their social experience on the Moodle™ e-learning ... [more ▼]

The main purpose of this Master Thesis was to invent and design Proactive Scenarios that could help students from the University of Luxembourg to improve their social experience on the Moodle™ e-learning platform through the automatic perception of who the user is, where does he/her come from, what are his/her online activities or what do users have in common, and through constant help, guidance and assistance generated by the system with the help of Proactivity. The first part of this work was dedicated to reading, analyzing and comparing stateof- the-art papers, articles and tools in research fields like Proactivity, Communities of Practice, Situation/Context Awareness and Learning Management Systems, followed by the creation and validation of the Proactive Cycle meant to group students, which are inscribed in the same study program or coming from the same city, into social communities where the practice can take multiple shapes. [less ▲]

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See detailSociality and Self-Organisation in Next-Generation Distributed Environments
Botev, Jean UL

Doctoral thesis (2011)

The proliferation of computationally powerful, interconnected devices entails a new generation of networked applications and social utilities characterized by a strong growth in scale and dynamics.<br ... [more ▼]

The proliferation of computationally powerful, interconnected devices entails a new generation of networked applications and social utilities characterized by a strong growth in scale and dynamics.<br />Distributed virtual environments constitute a privileged example, involving a high degree of interactivity as well as tightened constraints and requirements. As a response to these issues, this dissertation explores and substantiates sociality as a fundamental principle both in and for the design of such systems.<br />A specialized, dual peer-to-peer architecture is introduced, combining a highly-structured backbone overlay with a loosely-structured geometric client overlay synergistically complementing each other. To enable a global-scale, single-instanced environment, it is imperative to include as many client-side resources as possible and unburden the backbone. The focus of this dissertation therefore lies upon the latter, geometric overlay.<br />By taking an interdisciplinary perspective and leveraging different aspects of sociality, a series of self-organized approaches addressing major problem areas are proposed: a collaborative filtering mechanism for the handling of information overload created from the soaring amounts of users and objects; a confidentiality framework for the protection of sensitive data more likely exposed due to an increased interactivity; and two resource allocation schemes for fairly distributing surplus capacities in the face of critical regional surges.<br />Detailed evaluations show that these decentralized algorithms operate robustly and effectively, while yielding well-converging results in comparison to optimal, global-knowledge scenarios. [less ▲]

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See detailThe reading and mathematics performance of language-minority children in Luxembourg, Serbia and Europe: Is school instruction in their mother tongue important?
Aleksic, Gabrijela UL

Doctoral thesis (2011)

In order to explore the complex reality of the importance of mother tongue for the reading and mathematics performance of language-minority children, I conducted three studies. The aims of the studies ... [more ▼]

In order to explore the complex reality of the importance of mother tongue for the reading and mathematics performance of language-minority children, I conducted three studies. The aims of the studies were threefold: a) to investigate the reading and mathematics performance of language-minority preschool children in Luxembourg and Serbia (Study I). b) to identify predictors for early reading performance in the majority language (Study II). c) to conduct a meta-analysis on the effectiveness of bilingual as opposed to submersion programs in promoting the academic achievement of language-minority children (Study III). All three studies were theoretically anchored in the psycholinguistic constructs of Jim Cummins, as in OECD (2006, 2010) results reporting the underachievement of minority students in Europe. On the strength of this theory and drawing from empirical evidence, I propose three hypotheses: a) Hypothesis 1: language-minority children will score significantly lower in both reading and mathematics than language-majority children (Study I). b) Hypothesis 2: the significant predictors for early reading will be whether the test was conducted in the child’s mother tongue or not, the child’s gender, the level of education of the child’s parents, the child’s range of vocabulary, the child’s phonological awareness, competence in mathematics and the child’s behaviour (Study II). c) Hypothesis 3: bilingual education programs that include language-minority children’s mother tongue in school instruction are superior to submersion programs that exclude the children’s mother tongue in school instruction in promoting their academic achievement (Study III). International data show that those language-minority students who do not speak the school language of instruction at home are, on average, one year behind their native peers (Stanat & Christensen, 2007). This gap hampers student’s academic achievement, which in turn restrict the student’s opportunities in the labour market. The purpose of Study I was, therefore, to investigate the performance in reading and mathematics of language-minority preschool children in Luxembourg (N=174) and Serbia (N=159). MANOVA results showed that in Luxembourg, Portuguese children performed significantly lower than both native Luxembourgish children and other minority children. However, with regard to the testing of vocabulary and rhyming words - sections of the test which are evidently loaded with Luxembourgish-specific words - Portuguese and other minority children scored significantly lower than Luxembourgish children. I speculate that language of instruction can be one of the reasons for their possible low performance. In Serbia, Roma performed significantly lower than Hungarians, Serbs and other minority children. This finding may suggest that there are other variables, such as the socio-economic backgrounds of the children that may contribute to the low performance of both the Portuguese and Roma as language-minority groups at school. Thus, Hypothesis 1 is partly confirmed. Reading skills provide a crucial foundation for children’s success at school (Lonigan, Burgess, & Anthony, 2000) and beyond (Miles & Stipek, 2006). Good progress in reading and mathematics in the earliest years constitute the most important factors which continue to play a role at the age of 11 (Tymms, Jones, Albone, & Henderson, 2007). Study II, involving preschool children from Serbia (N=159) and Luxembourg (N=174), examines the predictive value of the child’s gender, the child’s mother tongue, the level of education of the child’s parents, the child’s range of vocabulary, the child’s phonological awareness, competence in mathematics and the child’s behaviour for early reading skills. For the Serbian sample, multilevel models showed that whether the test was administered in the child’s mother tongue at the age of 5 or not and competence in mathematics were the most significant predictors for early reading at the age of 7 after controlling for age, gender, vocabulary, phonics and behaviour. For the Luxembourgish sample, gender, vocabulary, phonological awareness and competence in mathematics at the age of 5 were significant predictors for reading at the same age, after controlling for age and the mother tongue. The level of parental education in the Serbian sample and the children’s behaviour in both samples proved not to be significant. Thus, Hypothesis 2 is partly confirmed. The education of language-minority children becomes increasingly important in today’s society. Five previous meta-analyses investigated the effectiveness of bilingual programs in promoting academic achievement of language-minority children in the United States. The present meta-analysis (Study III) investigates seven European studies on the topic. Results indicate a small positive effect (g=0.23) for bilingual over submersion programs on the academic achievement of language-minority children (also see Rolstad, Mahoney & Glass, 2005, 2008). This meta-analysis, therefore, appears to support bilingual education in Europe, the education that includes the mother tongue of language-minority children in the school instruction. Thus, Hypothesis 3 is confirmed. However, the results are restricted due to the small number of studies. More published studies in bilingual education in Europe are needed. [less ▲]

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See detailAnalysis of resynchronization mechanisms of stream ciphers
Priemuth-Schmid, Deike UL

Doctoral thesis (2011)

Stream ciphers are cryptographic primitives belonging to symmetric key cryptography to ensure data confidentiality of messages sent through an insecure communication channel. This thesis presents attacks ... [more ▼]

Stream ciphers are cryptographic primitives belonging to symmetric key cryptography to ensure data confidentiality of messages sent through an insecure communication channel. This thesis presents attacks on several stream ciphers, especially against their initialization methods. The first targets are the stream ciphers Salsa20 and Trivium. For both ciphers slid pairs are described. Salsa20 can be distinguished from a random function using only the slid pair relation. When a slid pair is given for Salsa20 both secret keys can be recovered immediately if the nonces and counters are known. Also an efficient search for a hidden slid pair in a large list of ciphertexts is shown. The efficiency of the birthday attack can be increased twice using slid pairs. For the cipher Trivium a large related-key class which produces identical keystreams up to a shift is presented. Then the resynchronization mechanism of the stream ciphers SNOW 3G and SNOW 2.0 is analyzed. Both ciphers are simplified by replacing all additions modulo 32 with XORs. A known IV key-recovery attack is presented for SNOW 3G and SNOW 2.0 where both ciphers have no feedback from the FSM. This attack works for any amount of initialization clocks. Then in both ciphers the feedback from the FSM is restored and the number of 33 initialization clocks is reduced. Chosen IV key-recovery attacks on SNOW 3G with 12 to 16 initialization clocks and SNOW 2.0 with 12 to 18 initialization clocks are shown. In a similar way versions of the stream cipher K2 are attacked. This cipher is simplified by replacing all additions modulo 32 with XORs as well. Chosen IV key-recovery attacks on versions with reduced initialization clocks from five to seven out of 24 are presented. For the version with seven initialization clocks also a chosen IV distinguishing attack is shown. The last part deals with a linear key-IV setup and known feedback polynomials of the shrinking generator. It is shown that this linear initialization results in a very weak cipher as only a few known IVs are required to recover the secret key. The original design of the shrinking generator does not include any initialization method so the initial state was assumed to be the secret key. [less ▲]

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See detailAn Alternative approach to extreme-risk management
Laube, Falk UL

Doctoral thesis (2011)

Detailed reference viewed: 53 (1 UL)
See detailDe Bonn à Berlin : territoires, mémoires et échelles du politique
Laporte, Antoine UL

Doctoral thesis (2011)

Detailed reference viewed: 37 (3 UL)
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See detailInhomogeneities of epitaxial chalcopyrites studied by photoluminescence
Larsen, Jes K. UL

Doctoral thesis (2011)

Detailed reference viewed: 224 (41 UL)
See detailLipid and Immune Functions of the Liver X Receptors in Human Macrophages
Diwo, Janine UL

Doctoral thesis (2011)

Detailed reference viewed: 53 (2 UL)
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See detailParallel hybrid optimization methods for permutation based problems
Mehdi, Malika UL

Doctoral thesis (2011)

Solving efficiently large benchmarks of NP-hard permutation-based problems requires the development of hybrid methods combining different classes of optimization algorithms. The key challenge here is how ... [more ▼]

Solving efficiently large benchmarks of NP-hard permutation-based problems requires the development of hybrid methods combining different classes of optimization algorithms. The key challenge here is how to find connections between the divergent search strategies used in each class of methods in order to build efficient hybridization strategies. Genetic algorithms (GAs) are very popular population-based metaheuristics based on stochastic evolutionary operators. The hybridization of GAs with tree-based exact methods such as Branch-and-Bound is a promising research trend. B&B algorithms are based on an implicit enumeration of the solution space represented as a tree. Our hybridization approach consists in providing a common solution and search space coding and associated search operators enabling an efficient cooperation between the two methods. The tree-based representation of the solution space is traditionally used in B&B algorithms to enumerate the solutions of the problem at hand. In this thesis, this special representation is adapted to metaheuristics. The encoding of permutations as natural numbers, which refer to their lexicographic enumeration in the tree, is proposed as a new way to represent the solution space of permutation problems in metaheuristics. Mapping functions between the two representations and special search operators are defined for general permutation problems. This common representation allows the design of efficient cooperation strategies between GAs and B&B algorithms. The proposed hybrid schemes have been parallelized and validated on standard benchmarks of the 3D quadratic assignment problem (Q3AP) using the computational grid Grid5000. [less ▲]

Detailed reference viewed: 63 (11 UL)
See detailThe principle of equality of arms in international criminal justice
Bengüsu, Özge UL

Doctoral thesis (2011)

Detailed reference viewed: 45 (8 UL)
See detailLie-admissible structures on Witt type algebras and automorphic algebras
Chopp, Mikael UL

Doctoral thesis (2011)

Detailed reference viewed: 39 (1 UL)
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See detailApplication of the Storing Matter technique to organic samples: fundamentals, applications, and evaluation of the analytical potential
Becker, Nora UL

Doctoral thesis (2011)

SIMS is a sensitive surface analysis method that is commonly used for a wide range of applications in various domains. Its major drawback is the so-called matrix effect, which is due to a change of the ... [more ▼]

SIMS is a sensitive surface analysis method that is commonly used for a wide range of applications in various domains. Its major drawback is the so-called matrix effect, which is due to a change of the ionization efficiency as a function of the chemical environment of the considered atom or molecule and which makes quantitative analysis very difficult. The Storing Matter technique was developed in order to circumvent the matrix effect while still keeping an excellent sensitivity: in a first step, the sample surface is sputtered by an ion beam and the emitted matter is deposited at sub-monolayer level onto a dedicated collector. Then the collector is transferred under UHV conditions to a SIMS instrument where the deposit is analyzed. If the deposit coverage is in the sub-monolayer range, all the deposited particles are surrounded by the same matrix, i.e. the collector material. The main goal of this work was the study and setup of experimental conditions for the application of the Storing Matter technique to organic samples. In this case, it is particularly important that molecular information is preserved. The key parameters of the technique were studied in detail and the optimal conditions with regard to high ionization efficiency and low fragmentation could be defined. [less ▲]

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See detailSecurity of RFID protocols
Van Deursen, Ton UL

Doctoral thesis (2011)

Radio-frequency identification (RFID) is a technology that uses radio waves to exchange data between RFID readers and tags. The low manufacturing costs and small size and the lack of need of a power ... [more ▼]

Radio-frequency identification (RFID) is a technology that uses radio waves to exchange data between RFID readers and tags. The low manufacturing costs and small size and the lack of need of a power source make RFID tags useful in many applications, but also impose a strong need for secure RFID protocols. The first part of this thesis considers the analysis of untraceability of RFID protocols. We start by designing a formal syntax and semantics for security protocols. We define untraceability as a property on the traces of a protocol. We find new untraceability flaws in a number of RFID protocols. Furthermore, we show that indistinguishability-based proof models are incomparable to unpredictability-based proof models. The second part of this thesis is concerned with authentication of RFID protocols. Authentication ensures that agents can not be impersonated. We categorize new authentication attacks into algebraic replay attacks, man-in-the-middle attacks, compositionality attacks, and cryptanalytic attacks. The third part of this thesis deals with formalizing ownership in RFID systems and related security properties. In dynamic environments where RFID tags are exchanged, sold, or traded, the owner of a tag may change. We define secure ownership, exclusive ownership, secure ownership transfer, and desynchronization resistance. The fourth part of this thesis describes the problem of recovering memory structures of systems. We define the carving problem as recovering the structure of the memory, based on an attributed dump set. We design and implement algorithms to find commonalities and dissimilarities and apply them to a deployed RFID system.   [less ▲]

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See detailDesign and Implementation of a Reliable Distributed Energy Management System
Hoben, Ralf UL

Doctoral thesis (2011)

Detailed reference viewed: 60 (6 UL)
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See detailHachage vers les courbes elliptiques et cryptanalyse de schémas RSA
Tibouchi, Mehdi UL

Doctoral thesis (2011)

This thesis consists of two independent parts, devoted to both aspects of cryptology: construction and analysis. Contributions to cryptography proper, on the one hand, address open questions in algebraic ... [more ▼]

This thesis consists of two independent parts, devoted to both aspects of cryptology: construction and analysis. Contributions to cryptography proper, on the one hand, address open questions in algebraic curve-based cryptography, particularly the problem of encoding and hashing to elliptic curves. We derive some quantitative results on curve-valued encoding functions, and give a satisfactory construction of hash functions based on those encodings, using a range of mathematical techniques from function field arithmetic, the algebraic geometry of curves and surfaces, and character sums. We also worked on a more implementation-related problem in elliptic curve cryptography, namely the construction of fast addition and doubling formulas. Our cryptanalytic work, on the other hand, focuses on RSA-based cryptosystems—mostly encryption and signature schemes. We have obtained and carried out new attacks on standardized padding schemes that remain in widespread use, including ISO/IEC 9796-2 for signatures and PKCS#1 v1.5 for encryption. We also propose new physical fault attacks on RSA signature schemes using the Chinese Remainder Theorem, and a stronger attack on RSA schemes relying on small hidden-order subgroups. The tools involved include index calculus, lattice reduction techniques and efficient arithmetic of large degree polynomials. [less ▲]

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See detailLe rapatriement prématuré: analyse des déterminants psychosociaux, de la qualité de vie, des compétences relatives à l'employabilité et des capacités à gérer des problèmes auprès des militaires des Forces canadiennes stationnés en Europe. De la conception à l'évaluation d'une intervention psychosociale pour le prévenir
Blackburn, Dave UL

Doctoral thesis (2011)

Introduction. Early repatriation of Canadian Forces personnel deployed to Europe, mainly to NATO, defines military members unable to complete their postings. This is a recent problem and its reoccurrence ... [more ▼]

Introduction. Early repatriation of Canadian Forces personnel deployed to Europe, mainly to NATO, defines military members unable to complete their postings. This is a recent problem and its reoccurrence and prohibitive costs have a psychological and social impact at individual, family and institutional levels and therefore, have become a research priority. This thesis includes a group of doctorate studies whose innovative character undoubtedly helps understand this phenomenon and the factors contributing to its persistence or continuity. Goals. 1) Identify the determining factors (personal, interpersonal, environmental, institutional and social) involved with early repatriation; 2) Analyze over a period of three months the connection between quality of life, employability skills and problem management capabilities; secondly, identify the links between psychological quality of life and the factors that are mentioned, as well as the sense of belonging and socio-demographic characteristics; 3) Develop a program of preventive psychosocial actions for CF members serving in Europe (Programme d’actions préventives psychosociales destiné aux militaires des FC affectés en Europe (PAPFCE)); 4) Assess, with a group of participants, the quality and usefulness of the different components involved in the psychosocial intervention program and analyze over a three month period, the relationship between quality of life, employability skills and problem management capabilities for one group of participants and two groups not participating in the program. Method. In order to reach our goals, 343 CF members were invited to participate in various investigations. 1) Comments from soldiers that repatriated to Canada were analyzed. 2) A questionnaire based on previously established scales, was built to measure quality of life, employability skills, ability to manage problems and sense of belonging for newcomers of summer 2009. 3) Creation of the PAPFCE was designed and submitted to the newcomers of summer 2010. 4) A data comparison was carried out between the non participating military members and those who participated in the psychosocial intervention. Furthermore, using an evaluation grid, military members subjected to psychosocial intervention were questioned about the usefulness and quality of the different parts of the program. Results. A total of 74 military members participated in the project (participation rate 22%). The participants were men (81.1%), average age of 41.8 years [from 23 years to 56 years], using English at home (59.5%) and reported living as married (81.1%). Their job profile is as follows: 20.7 years of service in the CF [from 5 years to 38 years], non commissioned officers (52.7%) and Germany as place of employment (54.1%). The main contributing factors to early repatriation are: 1) deficiencies in the military selection process and its application, 2) occurrence or development of psychosocial problems, 3) application of disciplinary or administrative actions (such as revealing psychosocial imbalance), 4) expectations that were unfulfilled by the posting. After the first three months of deployment, quality of life, employability skills and capability to manage problems have not changed. The military member’s psychological quality of life is positively associated with "physical" and "social" aspects, the extent of "acquisition of social support" and the "restructuring" of the capability to manage problems. A data comparison between military personnel who participated in the PAPFCE and the non participants neither confirms its effectiveness nor significant contribution. However, for most participants, the quality of components and their satisfaction with the program were positively assessed, although the program did not seem to be able to prevent the occurrence of psychosocial problems, major factors for premature repatriation. Conclusion. The analysis of the determining factors involved in the success or failure of a military posting to Europe has led to a better understanding of the complexity of the cultural and professional adjustment process necessary by the members and their families. This work provides site specific realities to reflect upon and possible intervention methods that can be adopted to improve the posting or deployment support and encourages a more critical observation of challenges and issues that may have an impact on the future of the CF. [less ▲]

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See detailResource-Aware routing in delay and disruption tolerant networks
Sandulescu, Gabriel UL

Doctoral thesis (2011)

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to ... [more ▼]

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to mention a few. This thesis studies the resource-aware routing problem in DTNs along four lines. First, the thesis presents the design and comparative evaluation of a delay-tolerant routing protocol (ORWAR) which optimises message transmission and bandwidth usage during opportunistic encounters. This is done through the estimation of contact duration between nodes, selection of the most suitable message to forward at any contact opportunity, and message differentiation. Second, the thesis proposes a hybrid scheme whereby opportunistic and infrastructure-based communication can be combined to overcome network partitions and packet losses. Collaboration between two networks characterised by different capacities, costs, and performance levels has been shown to be not only cost-effective, but also capable of increasing network survivability in the combined network. Third, it proposes and evaluates a mathematical model that can be used to compute the optimal level of redundancy and replication of a routing protocol as a function of message characteristics. Fourth, a holistic approach to resources is proposed, where variations in the spatial and temporal distribution of various resources can feed strategies to reduce resource consumption. Using estimates of vicinity resources, a routing protocol may not only use up fewer resources overall, but may also consume resources preferentially from nodes with higher resource levels, sparing whenever possible those with limited supplies. [less ▲]

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See detailEnergieeffizienz neuer Schul-und Bürogebäude in Luxemburg basierend auf Verbrauchsdaten und Simulationen
Thewes, Andreas UL

Doctoral thesis (2011)

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a ... [more ▼]

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a comprehensive data basis with real consumption figures that are not yet available. One focus of this study was to create a priori a detailed energy consumption database for new “School and Administrative Buildings” for Luxembourg. These are both groups cover a major part of the building and housing sector in Luxembourg besides residential buildings. Based on the samples collected, it was able to expand the figures to the entire country using mathematical methods and the medium heat and electricity consumption of these two types of buildings could determined. After collecting some details about each object, it was able to analyze the influence of different parameters, such as building age, size, type, glass fraction etc., on energy consumption using multivariate statistical methods. A posteriori, the results from the database were verified using parameter studies to existing objects and one object still under construction. Based on this, important key parameters relevant for both energy savings and thermal comfort could be found. This knowledge are necessary to understand energy flows within buildings better and, based on this, to be able meeting the nearly zero energy buildings requirements as set out by the EU Directive in the years to come. As conclusion, the central-European climatic zone provides opportunities to design energy-saving office and school buildings (primary energy consumption < 100 kWh/m2a) without mechanical cooling and ventilation systems that still guarantee appropriate degrees of thermal comfort. Unfortunately, the real average primary energy consumption figures of new school (187 kWh/m2a) and office buildings (677 kWh/m2a) in Luxemburg are still significantly higher. [less ▲]

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See detailPhysical Security of Cryptographic Algorithm Implementations
Kizhvatov, Ilya UL

Doctoral thesis (2011)

This thesis deals with physical attacks on implementations of cryptographic algorithms and countermeasures against these attacks. Physical attacks exploit properties of an implementation to recover secret ... [more ▼]

This thesis deals with physical attacks on implementations of cryptographic algorithms and countermeasures against these attacks. Physical attacks exploit properties of an implementation to recover secret cryptographic keys. Particularly vulnerable to physical attacks are embedded devices. In the area of side-channel analysis, this thesis addresses attacks that exploit observations of power consumption or electromagnetic leakage of the device and target symmetric cryptographic algorithms. First, this work proposes a new combination of two well-known attacks that is more efficient than each of the attacks individually. Second, this work studies attacks exploiting leakage induced by microprocessor cache mechanism, suggesting an algorithm that can recover the secret key in the presence of uncertainties in cache event detection from side-channel acquisitions. Third, practical side-channel attacks are discovered against the AES engine of the AVR XMEGA, a recent versatile microcontroller. In the area of fault analysis, this thesis extends existing attacks against the RSA digital signature algorithm implemented with the Chinese remainder theorem to a setting where parts of the signed message are unknown to the attacker. The new attacks are applicable in particular to several widely used standards in modern smart card applications. In the area of countermeasures, this work proposes a new algorithm for random delay generation in embedded software. The new algorithm is more efficient than the previously suggested algorithms since it introduces more uncertainty for the attacker with less performance overhead. The results presented in this thesis are practically validated in experiments with general-purpose 8-bit AVR and 32-bit ARM microcontrollers that are used in many embedded devices. [less ▲]

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See detailLa détresse financière des entreprises: trajectoire du déclin et traitement judiciaire du défaut
Fimayer, Agnès UL

Doctoral thesis (2011)

This thesis aims to evaluate the efficiency of bankruptcy laws on an ex ante and ex post point of view according to three criteria: their financial efficiency, their social efficiency and their ... [more ▼]

This thesis aims to evaluate the efficiency of bankruptcy laws on an ex ante and ex post point of view according to three criteria: their financial efficiency, their social efficiency and their macroeconomic coherence. First, we analyze the economic and financial path of default and its legal treatment in order to determine the potential costs induced by the social objectives (employment preservation) of French bankruptcy law in terms of recoveries for creditors. We find that the legal treatment of default is in France implemented in the spirit of the objectives defined and hierarchized by the law, and that the court undertakes measures in order to also protect financial interests; this result invalidates our hypothesis that these two objectives are incompatible. Subsequently, we adopt a Law and Finance approach in order to bind bankruptcy codes to national environments. We offer an appreciation of the macroeconomic degree of coherence of default, which is in our opinion an element of its efficiency. [less ▲]

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See detailZur Anwendung der statistischen Formanalyse
Giebel, Stefan UL

Doctoral thesis (2011)

In the following work we propose an introduction to Statistical Shape Analysis and adapt the procedures to three and four dimensional objects. Especially, in the case of four dimensional objects we show ... [more ▼]

In the following work we propose an introduction to Statistical Shape Analysis and adapt the procedures to three and four dimensional objects. Especially, in the case of four dimensional objects we show one possible approach of Dynamical Shape Analysis. In Shape Analysis we use parameters of the distribution as the mean shape, a representative shape of a group, to test the possibility of discriminating different kind of groups of objects. First-time we are using in the concept of Shape Analysis the variance. Furthermore we combine the Neural Networks with the Shape Analysis and also the tests used for discriminating groups with Answer Tree. To classify the objects well known procedures as Logistic Regression, Neural Networks, Discriminant Analysis and Answer Tree are used. For the application more than one hundred renal tumors in childhood, also more than one hundred electronic nose sensor data for different kind of odor quality and concentration as well as the behaviour of around fifty sexual serial murderer are measured and used. In all the disciplines a new approach in measurement of data is shown. The work shows furthermore, that all three fields Shape Analysis is applicable. The results of Shape Analysis and the classification afford the discrimination of different kind of objects. Shape Analysis could be one answer for classifying image data in the light of increasing image data. [less ▲]

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See detailSelf-Adaptive Honeypots Coercing and Assessing Attacker Behaviour
Wagener, Gerard UL

Doctoral thesis (2011)

Information security communities are always talking about "attackers" or "blackhats", but in reality very little is known about their skills. The idea of studying attacker behaviors was pioneered in the ... [more ▼]

Information security communities are always talking about "attackers" or "blackhats", but in reality very little is known about their skills. The idea of studying attacker behaviors was pioneered in the early nineties. In the last decade the number of attacks has increased exponentially and honeypots were introduced in order to gather information about attackers and to develop early-warning systems. Honeypots come in different flavors with respect to their interaction potential. A honeypot can be very restrictive, but this implies only a few interactions. However, if a honeypot is very tolerant, attackers can quickly achieve their goal. Choosing the best trade-off between attacker freedom and honeypot restrictions is challenging. In this dissertation, we address the issue of self-adaptive honeypots that can change their behavior and lure attackers into revealing as much information as possible about themselves. Rather than being allowed simply to carry out attacks, attackers are challenged by strategic interference from adaptive honeypots. The observation of the attackers' reactions is particularly interesting and, using derived measurable criteria, the attacker's skills and capabilities can be assessed by the honeypot operator. Attackers enter sequences of inputs on a compromised system which is generic enough to characterize most attacker behaviors. Based on these principles, we formally model the interactions of attackers with a compromised system. The key idea is to leverage game-theoretic concepts to define the configuration and reciprocal actions of high-interaction honeypots. We have also leveraged machine learning techniques for this task and have developed a honeypot that uses a variant of reinforcement learning in order to arrive at the best behavior when facing attackers. The honeypot is capable of adopting behavioral strategies that vary from blocking commands or returning erroneous messages, right up to insults that aim to irritate the intruder and serve as a reverse Turing Test distinguishing human attackers from machines. Our experimental results show that behavioral strategies are dependent on contextual parameters and can serve as advanced building blocks for intelligent honeypots. The knowledge obtained can be used either by the adaptive honeypots themselves or to reconfigure low-interaction honeypots. [less ▲]

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See detailRisk Management in the petrochemical industry - a game theoretic approach
Hansen, Michael UL

Doctoral thesis (2011)

The thesis studies risk management and the complex human interactions in the petrochemical industry using game theoretic methods. In a first step, the risk management problem is described as a ... [more ▼]

The thesis studies risk management and the complex human interactions in the petrochemical industry using game theoretic methods. In a first step, the risk management problem is described as a simultaneous inspection game, in which the management of a model petrochemical company makes a decision of safety rule enforcement and the worker faces a trade-off between not violating or violating these rules. Violating leads to a gain if rules are not enforced, and to a loss if enforced. In this simple model, comparative statics analyses show how increased punishment and increased management commitment increase safety standards in the company. The cost and benefit parameters of the analysis are adapted from the “real world”. In a second step, the risk management problem is described as an enhanced, sequential inspection game in which incident risks are considered. The equilibrium results are used to develop a graphical risk management tool, the “Petrochemical Organisation Risk Triangle” (PORT). The PORT demonstrates how an enhancement of safety culture in the industry decreases the risk of incident. Comparative statics analyses including the effects of technological progress, safety culture incentives, increased punishment, management commitment and external contractors are then discussed using the PORT. It is concluded that in improving a company’s safety culture, management commitment is more effective than increased punishment and that contractors are key players in achieving good safety performance. Finally, the thesis presents an economic cost and benefit analysis of a model company to quantify and evaluate current risk management practices based on industrial data. [less ▲]

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See detailDynamic modelling of ground antennas
Breyer, Laurent UL

Doctoral thesis (2011)

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See detailDas Verhältnis von Lebenswelt und Wissenschaft
Primc, Nadia UL

Doctoral thesis (2011)

The PhD thesis aims at the clarification of the relationship between our commonsense experience and the scientific explanation of the world around us. The sciences claim to provide knowledge of a special ... [more ▼]

The PhD thesis aims at the clarification of the relationship between our commonsense experience and the scientific explanation of the world around us. The sciences claim to provide knowledge of a special quality. The indication ‘scientifically proven’ for instance refers to the outstanding reliability of the findings and the verification procedures of the sciences. If this claim is not to be taken as an empty promise, it has to be shown wherein this particular quality of the scientific knowledge consists and in which way it differs from our ‘everyday’ knowledge. In conclusion, the thesis argues for the following view of the relationship between commonsense and scientific knowledge: Our everyday conceptions take their origin in the different practices that are pursued within our life-world. They are to be judged according their ability to back our everyday practices. The adequacy of these concepts does not reside in some correspondence to reality but in their appropriateness to the realisation of the different ends and practices that constitute our everyday business. The sciences have to be judged as well according their ability to back practices, namely the experimental and laboratory practices. The sciences are in addition subjected to the demand of a distinct and situation-invariant reproducibility of their results. For this purpose a standardisation of the scientific concepts is needed, which can rely on commonsense distinctions and concepts as its methodological starting point. As the particular quality of the sciences is located in this claim to distinctness and situation-invariance they cannot be regarded as per definition superior to our everyday knowledge. [less ▲]

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See detailPhotoluminescence measurements on solar cell materials: chalcopyrites and kesterites
Hones, Katja UL

Doctoral thesis (2011)

The chalcopyrite Cu(In,Ga)Se2 is by now an established semiconductor for thin film solar cells. Its electrical properties is governed by native defects as for example copper vacancies VCu. However despite ... [more ▼]

The chalcopyrite Cu(In,Ga)Se2 is by now an established semiconductor for thin film solar cells. Its electrical properties is governed by native defects as for example copper vacancies VCu. However despite the good efficiencies, not much is known about the chemical nature of the defects responsible for the doping. The symmetry of the defects might be one way to determine their chemical nature. The symmetry of the defects will be investigated in this Ph.D. thesis by polarisation dependent photoluminescence measurements on epitaxial CuInSe2 and CuGaSe2 samples and on a CuInSe2 crystal. One major concern in fabricating thin film solar cells from the chalcopyrite Cu(In,Ga)Se2 is the indium price. One possibility to overcome this drawback is to replace the group III element indium by isoelectrical substitution by more abundant elements like zinc and tin, from the second and fourth group of the periodic table. This leads from the chalcopyrite CuInSe2 to the kesterite Cu2ZnSnSe4. However, synthesizing a quaternary compound, additional secondary and ternary phases become an important issue. In this Ph.D. thesis photoluminescence and X-ray diffraction results will be presented and their strengths and limits in the identification of secondary and ternary phases will be discussed. As kesterite is expected to be, similar to the chalcopyrites, a natively doped semiconductor, the defects will play a crucial role for the device properties. Therefore, in the third part of the Ph.D. thesis photoluminescence results on defects in kesterites, measured on PVD grown kesterite samples, will be discussed. [less ▲]

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See detailJustice distributive: La question des brevets entre libéralisme et libertarisme
Lasalle, Matthieu UL

Doctoral thesis (2011)

The patent system as we know it is the only legal monopolistic system in the world. If collusion between different corporations in order to control the price of some ressources or produces is illegal ... [more ▼]

The patent system as we know it is the only legal monopolistic system in the world. If collusion between different corporations in order to control the price of some ressources or produces is illegal, there is almost nothing on the opposite side that exists in order to control the monopolistic system of the patents. When it comes to entertainment or inventions that aren't necessaries to our survival, the patent system, though failed, is not as problematic as when one owns for over 20 years the exclusivity on something that is vital to the survival of many. The knot of the problem is located between the patent that protects the creative minds from getting their ideas stolen and the problem that this protection causes by its monopolistic system. The aim of this work was to scrutinize deeper this complex problematic through a libertarian approach that claims that one shall dispose of what he wants the way he wants it and a rawlsian type of liberal approach that claims that we should consider patents as wealth that should be as well be subdued under some conditions to a form of redistribution as well. [less ▲]

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See detailInsider dealing and criminal law: les liaisons dangereuses?
Seredynska, Iwona UL

Doctoral thesis (2011)

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See detailEnhancing Project Robustness: A Risk Management Perspective
Gericke, Kilian UL

Doctoral thesis (2011)

Product development projects are challenging management tasks. The complexity and dynamics of requirements and goals, the novelty of design tasks, and polytely (striving for multiple goals) can all affect ... [more ▼]

Product development projects are challenging management tasks. The complexity and dynamics of requirements and goals, the novelty of design tasks, and polytely (striving for multiple goals) can all affect the course of a project. Frequent consequences of these boundary conditions are unwanted events which inhibit a successful project. This work shall provide a better understanding of project robustness, its barriers and enablers. To achieve this goal, the work was conducted following a research approach based on the Design Research Methodology proposed by Blessing and Chakrabarti. The work is based on a comprehensive literature study which resulted in a model describing the causality of project failures. The underlying assumption of the project failure causality model, that companies which treat risks preventively and proactively are more likely to successfully finish their product development projects than other companies, is examined by an analysis of data from 141 small and medium sized enterprises (SMEs). Design methodologies, project management, risk management and maturity models such as the Capability Maturity Model Integration (CMMI) are proposed in order to support product development. The study validates the importance of the use of these systematic approaches to support product development projects, but none of the considered approaches on its own will secure project success. This suggests that the expected benefit (a robust project) can only be achieved using different approaches conjointly. While design methodologies and project management offer a rich support for development activities, risk management supports the project specific selection of appropriate risk treatment measures. A result of this work is a support for the pre-selection of risk treatment strategies based on the project failure causality model and its link to the proposed categorisation of risk treatment strategies. In this dissertation it is shown that the proposed categorisation of risk treatment strategies, the categorisation of the risk impact evolvement, and the question based support were easily understood by industrial experts. Their feedback validates the applicability and acceptance of the question based support as helpful for risk treatment strategy pre-selection, but also lead to a revision of the proposed support. The result is a matrix based support, intended to contribute to an enhancement of project robustness by supporting the process of risk treatment strategy selection which is currently only insufficiently supported. The matrix based support considers, in addition to traditional risk characteristics (likelihood of occurrence and severity of impact) the time-dependent evolvement of risk impacts. [less ▲]

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See detailCryptanalysis and design of symmetric primitives
Nicolic, Ivica UL

Doctoral thesis (2011)

Cryptographic primitives are the basic building blocks of various cryptographic systems and protocols. Their application is based on their well established properties. The security of a crypto system is ... [more ▼]

Cryptographic primitives are the basic building blocks of various cryptographic systems and protocols. Their application is based on their well established properties. The security of a crypto system is proven under the assumption that the underlying cryptographic primitives provide some specific security levels. Therefore it is critical to use primitives that can meet these requirements. However, there is no general approach of constructing fast and provably secure primitives. Rather, the primitives undergo years of thorough cryptanalysis and only after no attacks have been found, they can be considered for real world applications. This PhD thesis deals with the two main cryptographic primitives: block ciphers and cryptographic hash functions. The main contribution lies in presenting attacks on these algorithms. The analysis ranges from finding ad-hoc differential trails that are used for collision search and distinguishers on specific hash functions to automatic search tools that give the optimal differential trails for block ciphers. Weaknesses are shown for a number of SHA-3 candidates in the framework of rotational distinguishers and meet in-the-middle based preimage attacks. [less ▲]

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See detailEssays on corporate default process: UK and France
Nigam, Nirjhar UL

Doctoral thesis (2011)

The thesis has been conducted upon a unique and primary database manually collected through courts and various reliable sources (governmental and non-governmental offices). This is the major strength of ... [more ▼]

The thesis has been conducted upon a unique and primary database manually collected through courts and various reliable sources (governmental and non-governmental offices). This is the major strength of this thesis. With such a database, we built individual statistics on the corporate bankruptcies process in for two major European countries (France and United Kingdom). The collected data deals with the causes of financial default, the recovery rates of creditors, the process of decision making at the time of default, the efficiency of such decisions, etc. Such research project helps in distinguishing the origins of corporate financial default: are they independent from the national bankruptcy code or not? In order to test the effect of legal environment, we computed the most comprehensive legal indexes till date. Our legal indexes consist of more than 300 questions that explain the particular function of bankruptcy. We merge these indexes with the hand collected database for France and UK. This makes this thesis really unique as it is composed of original hand collected databases. To the best of our knowledge the UK database has no equivalence as for the first time we manage to include liquidations which constitute more than 85% of bankruptcies in UK. Even the scholars in UK lack such information. Such empirical work is completed by a microeconomic theoretical analysis and would yield interesting results that will be discussed in detail in the rest of the chapters of the thesis and also open avenues for future research work. Chapter 1 presents a brief introduction to the topic, explaining the research aims and research methodology. Chapter 2 presents the detailed survey of literature on bankruptcy. It starts by explaining the basic concept associated with bankruptcy, need of bankruptcy laws, the main objective of bankruptcy, the main processes associated with bankruptcy, classification of bankruptcy regimes and the law and finance approach to understand legal environment affecting bankruptcy. It explores the previous literature and findings and provides our contribution to the pre-existing literature and justifies our research goals and our approach. Chapter 3 empirically investigates the choice between informal and formal (court-supervised) restructuring of small and medium French firms in default. The procedure is depicted as a sequential game in which stakeholders first decide whether or not to engage in an informal negotiation. Then, conditional on opting for an informal workout, the creditors and the debtor can succeed or fail in reaching an agreement in order to restructure the firm’s capital structure. Based on a sample of 735 credit lines allocated to 386 French distressed firms, we test different hypotheses which captures i) coordination vs. bargaining power issues, ii) informational problems, iii) firms’ characteristics, and iv) loan characteristics. Using a sequential LOGIT approach, we first find that the probability for opting for an informal workout i) decreases when the bank is the debtor’s main creditor and ii) increases with the size of the loan. In addition, the likelihood of success of an informal workout i) decreases when the management of a badly rated firm is considered as incompetent, and ii) decreases when the bank is the debtor’s main creditor. The result concerning the bank as being the main creditor suggests that “bargaining power” argument dominates the “coordination” argument. Finally, we find no evidence of the impact of collateral on the decision between informal and formal restructuring. Chapter 4 describes the prevalent bankruptcy procedure of UK and France; in general it provides an entire macro view of the bankruptcy laws in given two countries. It presents the various formal and informal procedures, explains their functioning, how they are triggered and the underlying specificities about each process. It is very crucial to understand the working of each procedure as this forms the basis for the future chapters where we related the result of our summary statistics and econometrics to specificities of these procedure and come up with useful conclusions and insights. In chapter 5 the focus returns to the micro economic analysis. We explore the two unique hand coded databases, collected through different sources. Our database consists of 264 small and medium sized enterprises representing France and 564 small and medium sized enterprises representing UK. These countries represent two major legal systems prevailing in Europe: common law and civil law. Both legislations have features that are of interest for research. Based on are datasets we provide summary statistics on both the countries. Our descriptive statistics explains the average profile of our sample company, it provides us with the reasons that lead the company into bankruptcy, it provides us the detailed asset and liability structures of the firms and the detailed claim structure and recovery structure. In addition it also provides us with the duration of the procedure and the costs involved in the process. We also perform multivariate analysis to test the choice between continuation and liquidation for France and to test the factors that increase or decrease the chances of receivership (procedure made for the benefits of banks) and administration (regarded as reorganization procedure) in UK. The main aim of the chapter 6 is to find the legal characteristics that impact on the recovery rates. Previous studies (LLSV, Doing Business Report, World Bank) have usefully used a set of legal indexes to rank the bankruptcy law prevalent within the country. But they fail to identify the characteristics of bankruptcy procedures that create more recoveries. We give here elements of answer by taking into consideration two countries that are good representatives of the two main legal systems prevailing in Europe: France (Civil Law) and United Kingdom (Common Law). To enable this, we built original legal indexes comprising of 158 binary questions that highlight ten major dimensions of corporate bankruptcy procedures: (1) accessibility, (2) exclusivity, (3) bankruptcy costs, (4) production of information, (5) protection of the debtor’s assets, (6) protection of claims, (7) coordination of creditors, (8) decision power, (9) sanction of faulty management, and (10) inclination towards liquidation / reorganization. We then propose a mapping of procedures that shows a clear specialization between them. The French procedures (“redressement judiciaire” and “liquidation judiciaire”) are more protective of the debtor’s assets and favor more the coordination of secured claims, public claims, and unsecured claims. In UK, we find strong opposition between the procedures oriented to liquidation and the other procedures. [less ▲]

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See detailExpertise und diagnostische Urteilsbildung : ein sozial-kognitiver Ansatz
Böhmer, Matthias UL

Doctoral thesis (2011)

In this thesis experts’ diagnostic judgment formation is seen as a social cognitive process: It is analyzed as a person-related judgment and is investigated according to the social cognition paradigm. The ... [more ▼]

In this thesis experts’ diagnostic judgment formation is seen as a social cognitive process: It is analyzed as a person-related judgment and is investigated according to the social cognition paradigm. The theoretical foundation is provided by dual process models (e.g. continuum model), which assume two different strategies of person-related information processing in order to form a judgment. The heuristic strategy is characterized by a categorization process and the corresponding activation of a specific person category. The information integrating strategy focuses on individual characterization of a person and the corresponding collection and integration of individual person attributes. A judge’s expertise is acknowledged to have an essential influence on the process of judgment formation. Experts, in contrast to laymen, are able to switch between the two strategies. The degree to which diagnostic judgment formation can be described by means of dual process models is investigated in a series of four quasi-experiments including psychotherapists and teachers as experts and students and staff members of Saarland University as laymen. Thus, social judgment formation is compared in two different domains. Two experiments focus on judgment itself by measuring judgmental data. The two other experiments focus on attention allocation and person memory by measuring self-paced reading time and free recall. Results show the expected pattern in both professional domains. Both psychotherapists and teachers are able to switch between the two strategies. So experts’ diagnostic judgment formation can be described by means of dual process models. [less ▲]

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See detailBeing a newcomer in a multilingual school : a case study
Gómez Fernández, Roberto UL

Doctoral thesis (2011)

The present thesis aims at understanding the process of becoming a member in a diverse and multilingual primary school in Luxembourg. It is a case study about one child belonging to one of the ethnic and ... [more ▼]

The present thesis aims at understanding the process of becoming a member in a diverse and multilingual primary school in Luxembourg. It is a case study about one child belonging to one of the ethnic and linguistic communities most affected by school failure. ‘Romanophones’ or romance-language speaking students in Luxembourg are touched by low achievement rates of school success. Also newcomers find themselves in challenging situations and are also affected by this problem. By following this child during one academic year an epistemological conflict between ‘agentivity’ and ‘structure’ is proposed. The seven-year old child, Nuno, had to follow lessons in German and Luxembourgish when he had no knowledge of these languages at all at his arrival in November from another primary school in Brazil. A close look at his interactions and identity processes with his peers and teachers revealed a re-evaluation of Nuno’s capital and resources which affected his academic progress as well as his identity during the year. This re-evaluation resulted in a “decapitalization” (Martín Rojo, 2008; 2010) of some of Nuno’s pre-existing resources (e.g., Portuguese language), which could otherwise be used as a positive resource in his progression towards “full membership”, and the eventual formation of a “community of practice”. Nuno’s initial agentivity resisted categorizations and also what could be classified as gatekeeping practices towards him. Along the academic year some major changes took place (a change of teacher and teaching philosophies, the arrival of another Brazilian newcomer) which affected Nuno’s behaviour, learning and identity. The interview data and the audio-visual recordings provide insights into the difficulties a ‘romanophone’ newcomer must confront as well as the fact that a community of practice is in constant construction. [less ▲]

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See detailL’accès du public aux documents des institutions européennes: le développement d’un droit et sa mise en application (1973-2004)
Bagias, Andreas UL

Doctoral thesis (2011)

Access to official documents is a key outcome of the concept of transparency as applied to the institutions of the European Union. In the 1990s, transparency offered the promise of a cure to the ... [more ▼]

Access to official documents is a key outcome of the concept of transparency as applied to the institutions of the European Union. In the 1990s, transparency offered the promise of a cure to the “democratic deficit” from which these European institutions suffered. Key factors that underpinned progress towards greater transparency and the right of access to documents are identified as: the influence of globalization and the gradual adoption of national legislations of the various member states, the “Citizens Europe” movement, the legal evolution concerning access to environmental information, the institutional evolution of the European decision-making process, the difficulties encountered during the ratification of the Maastricht Treaty and, the accession of Sweden and Finland in 1995 to the European Union. These developments culminated with the insertion of article 255 to the Amsterdam Treaty and, under the 2001 presidency of Sweden, the adoption of Regulation (EC) No 1049/2001. Official statistics reveal, however, that the right of access to documents, produced and received by the European institutions, is rarely applied by European citizens. This right, like a working knowledge of the functioning of the European Union, remains the preserve of a small circle of professionals, usually established in Brussels. It seems that transparency and the right of access to documents does not bring the citizen closer to the European institutions and it does not solve the stated “democratic deficit”. Rather, this research finds that it has been used as an instrument in an institutional struggle to limit the power of the Council and the Commission. [less ▲]

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See detailGenetic Algorithm based roadmapping: A method for product innovation
Suzianti, Amalia UL

Doctoral thesis (2011)

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See detailElectronic structure and optical properties of III-N nanowires
Molina-Sanchez, Alejandro UL

Doctoral thesis (2011)

The term III-N nanowire (NW) will refer throughout this work to the free-standing nanowires made of group-III-nitrides semiconductors, namely InN, GaN and AlN. These nanostructures have a large length ... [more ▼]

The term III-N nanowire (NW) will refer throughout this work to the free-standing nanowires made of group-III-nitrides semiconductors, namely InN, GaN and AlN. These nanostructures have a large length/diameter ratio, of the order of 100 (sev- eral micrometers versus tenths of nanometers). The term free-standing highlights the fact that the NWs are not embedded in another material. The improvement of the epitaxial techniques, and in particular, those based on III-N semiconductors, has lead an important part of the Solid State Physics community to concentrate the attention in the last years towards a better understanding of the physical properties of those NWs. Nanowires present several di erences with respect to the still widely investi- gated two-dimensional layers and the zero-dimensional nanostructures (quantum dots). We would like to highlight the following: (i) Nanowires grow strain-free (except maybe at their base), and thus with a minimal presence of dislocations or defects along the main structure. This fact opens the possibility of growing high- quality materials with an important lattice mismatch with the substrate, contrary to the situation found in quantum dots or superlattices. (ii) Depending on the NW lateral dimensions, two types of NWs can be distinguished. When the diameter is larger than 20 nm, the electronic properties of the NWs can be considered as that of a bulk material, thus making them a suitable platform to study the bulk optical and transport properties, which can be hardly investigated in bulk samples (thin lms), that grow with a high density of defects, when there is a high lattice mismatch with the substrate. (iii) For NWs of smaller diameters (. 20 nm), on the other hand, the e ects of quantum con nement can lead to important changes in the optical and transport properties, which can open the possibility of tuning the NW properties by controlling their size. One can roughly classify the investigations on nanowires into three main re- search lines. The rst one concerns the fabrication, being the molecular beam epitaxy or/and the metal organic chemical vapor deposition (MOCVD) the two techniques that allow the growth of higher quality NWs. This research area is in 2 constant development, and is not limited only to the growth of pure compound NWs, but also alloy-based NWs, which extend the possibilities of allowing beyond those possible in standard bulk growth, or axially and radially structured NWs. New physical phenomena arise which must be tacked by the physical community, in particular the e ect of the surface in the optical and transport properties of the NWs. Another focus of research is based on applications to optoelectronics devices and photovoltaic cells. In particular, III-N NWs, as InN, GaN and AlN, have attracted a special interest of the scienti c community, due to the band gap engineering. InN has a band gap of 0.67 eV (1852 nm), in the infrared, whereas GaN and AlN have a band gap of 3.5 eV (355 nm) and 6.2 eV (200 nm), respec- tively, in the ultraviolet. This opens the possibility of covering the whole solar spectrum by an appropriate alloying. In this context, the theory and numerical simulations play a crucial role in the explanation of NWs properties and a better understanding of the observed phenomena. The predictions o ered by the theory can also drive the fabrication of new heterostructures and the design of devices. In this work, we have studied theoretically by using several models, the fundamental aspects of the electronic structure and optical properties of the III-N bulk semiconductors in the rst place, and have applied afterwards such models to the investigation of the III-N nanowires physical properties. [less ▲]

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See detailThe (Mis-)Measure of Children’s Cognitive Abilities.
Baudson, Tanja Gabriele UL

Doctoral thesis (2011)

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See detailTraining und Transfer des komplexen Problemlösens
Kretzschmar, André UL

Bachelor/master dissertation (2011)

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See detailNarrateur, personnage et leceur virtuel: vers une méthode d'analyse intra-relationnelle
Goin, Emilie UL

Bachelor/master dissertation (2011)

[fr] Dans l'étude d'un possible dialogisme entre les instances internes au récit que sont le narrateur, le personnage et le lecteur virtuel (soit l'instance de lecture présupposée par le texte), ce ... [more ▼]

[fr] Dans l'étude d'un possible dialogisme entre les instances internes au récit que sont le narrateur, le personnage et le lecteur virtuel (soit l'instance de lecture présupposée par le texte), ce travail pose notamment les questions des subjectivèmes, de leur assemblage en point de vue et des articulations de points de vue hétérogènes: comment peut-on les repérer, identifier différentes formes d'assemblage/articulation et déterminer leur force illocutoire? [less ▲]

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See detailBeing a Newcomer in a Multilingual School: A Case Study
Gomez-Fernandez, Roberto UL

Doctoral thesis (2011)

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See detailReservoir Computing Architectures for Modeling Robot Navigation Systems
Antonelo, Eric Aislan UL

Doctoral thesis (2011)

This thesis proposes a new efficient and biologically inspired way of modeling navigation tasks for autonomous mobile robots having restrictions on cost, energy consumption, and computational complexity ... [more ▼]

This thesis proposes a new efficient and biologically inspired way of modeling navigation tasks for autonomous mobile robots having restrictions on cost, energy consumption, and computational complexity (such as household and assistant robots). It is based on the recently proposed Reservoir Computing approach for training Recurrent Neural Networks. Robot Navigation Systems Autonomous mobile robots must be able to safely and purposefully navigate in complex dynamic environments, preferentially considering a restricted amount of computational power as well as limited energy consumption. In order to turn these robots into commercially viable domestic products with intelligent, abstract computational capabilities, it is also necessary to use inexpensive sensory apparatus such as a few infra-red distance sensors of limited accuracy. Current state-of-the-art methods for robot localization and navigation require fully equipped robotic platforms usually possessing expensive laser scanners for environment mapping, a considerable amount of computational power, and extensive explicit modeling of the environment and of the task. This thesis The research presented in this thesis is a step towards creating intelligent autonomous mobile robots with abstract reasoning capabilities using a limited number of very simple raw noisy sensory signals, such as distance sensors. The basic assumption is that the low-dimensional sensory signal can be projected into a high-dimensional dynamic space where learning and computation is performed by linear methods (such as linear regression), overcoming sensor aliasing problems commonly found in robot navigation tasks. This form of computation is known in the literature as Reservoir Computing (RC), and the Echo State Network is a particular RC model used in this work and characterized by having the high-dimensional space implemented by a discrete analog recurrent neural network with fading memory properties. This thesis proposes a number of Reservoir Computing architectures which can be used in a variety of autonomous navigation tasks, by modeling implicit abstract representations of an environment as well as navigation behaviors which can be sequentially executed in the physical environment or simulated as a plan in deliberative goal-directed tasks. Navigation attractors A navigation attractor is a reactive robot behavior defined by a temporal pattern of sensory-motor coupling through the environment space. Under this scheme, a robot tends to follow a trajectory with attractor-like characteristics in space. These navigation attractors are characterized by being robust to noise and unpredictable events and by having inherent collision avoidance skills. In this work, it is shown that an RC network can model not only one behavior, but multiple navigation behaviors by shifting the operating point of the dynamical reservoir system into different \emph{sub-space attractors} using additional external inputs representing the selected behavior. The sub-space attractors emerge from the coupling existing between the RC network, which controls the autonomous robot, and the environment. All this is achieved under an imitation learning framework which trains the RC network using examples of navigation behaviors generated by a supervisor controller or a human. Implicit spatial representations From the stream of sensory input given by distance sensors, it is possible to construct implicit spatial representations of an environment by using Reservoir Computing networks. These networks are trained in a supervised way to predict locations at different levels of abstraction, from continuous-valued robot's pose in the global coordinate's frame, to more abstract locations such as small delimited areas and rooms of a robot environment. The high-dimensional reservoir projects the sensory input into a dynamic system space, whose characteristic fading memory disambiguates the sensory space, solving the sensor aliasing problems where multiple different locations generate similar sensory readings from the robot's perspective. Hierarchical networks for goal-directed navigation It is possible to model navigation attractors and implicit spatial representations with the same type of RC network. By constructing an hierarchical RC architecture which combines the aforementioned modeling skills in two different reservoir modules operating at different timescales, it is possible to achieve complex context-dependent sensory-motor coupling in unknown environments. The general idea is that the network trained to predict the location and orientation of the robot in this architecture can be used to select appropriate navigation attractors according to the current context, by shifting the operating point of the navigation reservoir to a sub-space attractor. As the robot navigates from one room to the next, a corresponding context switch selects a new reactive navigation behavior. This continuous sequence of context switches and reactive behaviors, when combined with an external input indicating the destination room, leads ultimately to a goal-directed navigation system, purely trained in a supervised way with examples of sensory-motor coupling. Generative modeling of environment-robot dynamics RC networks trained to predict the position of the robot from the sensory signals learns forward models of the robot. By using a generative RC network which predicts not only locations but also sensory nodes, it is possible to use the network in the opposite direction for predicting local environmental sensory perceptions from the robot position as input, thus learning an inverse model. The implicit map learned by forward models can be made explicit, by running the RC network in reverse: predict the local sensory signals given the location of the robot as input (inverse model). which are fed back to the reservoir, it is possible to internally predict future scenarios and behaviors without actually experiencing them in the current environment (a process analogous to dreaming), constituting a planning-like capability which opens new possibilities for deliberative navigation systems. Unsupervised learning of spatial representations In order to achieve a higher degree of autonomy in the learning process of RC-based navigation systems which use implicit learned models of the environment for goal-directed navigation, a new architecture is proposed. Instead of using linear regression, an unsupervised learning method which extracts slowly-varying output signals from the reservoir states, called Slow Feature Analysis, is used to generate self-organized spatial representations at the output layer, without the requirement of labeling training data with the desired locations. It is shown experimentally that the proposed RC-SFA architecture is empowered with an unique combination of short-term memory and non-linear transformations which overcomes the hidden state problem present in robot navigation tasks. In addition, experiments with simulated and real robots indicate that spatial activations generated by the trained network show similarities to the activations of CA1 hippocampal cells of rats (a specific group of neurons in the hippocampus). [less ▲]

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See detailRobust topology management in DT-MANETs: An efficient tree-based decentralized and multi-objective approach
Piyatumrong, Apivadee UL

Doctoral thesis (2010)

Delay-tolerant mobile ad hoc network (DT-MANETs) feature frequent and long duration partitioned MANETs. It is a challenged environment where end-to-end connectivity cannot always be obtained. Furthermore ... [more ▼]

Delay-tolerant mobile ad hoc network (DT-MANETs) feature frequent and long duration partitioned MANETs. It is a challenged environment where end-to-end connectivity cannot always be obtained. Furthermore, communication in such network is heavily relying on collaboration between nodes since there is no central authority. Limited resources of communication nodes present another facet of problems in such network. Moreover, the communication is typically done using wireless technologies which are sharing among communication nodes. In order to provide a better quality of service in such environment, topology management technique is used to help controlling network topology. The aim is to manage network resource and to enhance efficiency of communication. In this work, we proposed to do it by constructing an efficient and robust tree-based topology. We model the environment using dynamic and partitioned graph. Under such circumstances, protocols must withstand topology and condition changing. In summary, doing topology management in DT-MANETs encounters the following issues: cooperation among nodes, limitation of resources of mobile node, sharing medium, dynamic and partitioned topology and unrealistic and unscalable approach of centralized algorithm in such environment. This study focuses on managing tree-based topology in DT-MANETs. A set of active links is managed such that the deterioration of network is avoid and the quality of service in DT-MANETs is enhanced. Efficiency and robustness metrics are proposed accordingly. This work proposed to use different quality criteria based on communication node and edge for the selection topology. Both single- and multi-objectives tree-based topology are studied. Algorithms for managing tree-based topology are proposed according to different objectives. All proposed algorithms are purely decentralized, asynchronous algorithm and use one-hop information. [less ▲]

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See detailModalités du développement professionnel d'enseignants du préscolaire et du primaire, dans le domaine du plurilinguisme: conception et évaluation d'une formation continue dans un pays plurilingue (Luxembourg)
Elcheroth, Sylvie UL

Doctoral thesis (2010)

This action-research consists in designing, implementing and evaluating the continuous teacher education programme ‘Ecole multilingue’. The programme is aimed at preschool and primary school teachers and ... [more ▼]

This action-research consists in designing, implementing and evaluating the continuous teacher education programme ‘Ecole multilingue’. The programme is aimed at preschool and primary school teachers and concerns the pedagogy of multilingualism. During the programme, video excerpts showing language learning practices at school were studied, multilingual projects were designed and implemented in the classes of the participants and discussions and exchanges took place within ten monthly meetings. The research questions are the following: What is the professional development that is realised throughout the programme? What are the characteristics of the programme that have afforded this development? The research positions itself within the framework of socio-constructivist and socio-cultural theories. The chosen methodology draws upon thematic analysis, grounded theory, analysis of interactions and analysis of practice. It implies the collection of different types of data: questionnaire, videotapes and transcriptions of the training meetings, logbook of the trainer-researcher, videotapes and descriptions of innovative practices. During the research process, description and analysis grids are used and designed, and research results are cut across. A reflexion about the double role of a trainer and a researcher is developed. The analysis reveals the representations about language learning, multilingual practices and institutional context, as well as the ways of analysing pupils’ learning processes, co-constructed by the participants. It characterises the innovative multilingual practices that the participants have developed in their classes, and it shows the process of accompanying-challenging by the trainer. It furthermore brings out the ways in which the different elements of the programme have contributed to the teachers’ development. It finally may inform a prospective, improved training programme. [less ▲]

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See detailCUBA: Artificial conviviality and user-behaviour analysis in web-feeds
Kaufmann, Sascha UL

Doctoral thesis (2010)

Conviviality is a concept of great depth that plays an important role in any social interaction. A convivial relation between individuals is one that allows the participating individuals to behave and ... [more ▼]

Conviviality is a concept of great depth that plays an important role in any social interaction. A convivial relation between individuals is one that allows the participating individuals to behave and interact with each other following a set of conventions that are shared, commonly agreed upon, or at least understood. This presupposes an implicit or an explicit regulation mechanism based on consensus or social contracts and applies to the behaviours and interactions of participating individuals. With respect to an intelligent web-based system, an applicable social contribution is the give of assistance to other users in situations that are unclear and in guiding him to find the right decision whenever a conflict arises. Such a convivial social biotope deeply depends on both implicit and explicit co-operation and collaboration of natural users inside a community. Here, the individual conviviality may benefit from “The Wisdom of Crowds”, which fosters a dynamic understanding of the user’s behaviour and a strong influence of an individual’s well being to another person(s). The web-based system CUBA focus on such a behavioural analysis through profiling and demonstrates a convivial stay within a web-based feed system. [less ▲]

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See detailDT4BP: a Business Process Modelling Language for Dependable Time-Constrained Business Processes
Capozucca, Alfredo UL

Doctoral thesis (2010)

Today, numerous organisations rely on information software systems to run their businesses. The effectiveness of the information software system then, depends largely on the degree to which the ... [more ▼]

Today, numerous organisations rely on information software systems to run their businesses. The effectiveness of the information software system then, depends largely on the degree to which the organisation's business is accurately captured in the business model. The business model is an abstract description of the way an organisation's functions. Thus, the more precise the business model, the more accurate the requirement definition of the information software system to be engineered.There are an abundance of tools and notations available today to support the development of many types of business process. Many of these artifacts rely on the concept of a business process to describe a business model. A business process is commonly known as a set of one or more linked procedures or activities which collectively realise a business objective or policy goal, normally within the context of an organisational structure defining functional roles and relationships". This thesis is concerned with modelling business processes as a means to accurately capture an organisation's activities and thus, the requirements of the software system that supports these activities.Among the infinite set of possible business processes, this thesis targets only those characterized by the qualities of dependability, collaboration and time. Business processes having these specific dimensions are referred to as Dependable, Collaborative and Time-Constrained (DCTC) business processes. A dependable business process is one whose failures or the number of occurrences in which business process misses its goal are not unacceptably frequent or severe (from certain viewpoint). A collaborative business process is one that requires the interaction of multiple participants to attain its goal. A time-constrained business process is one that owns at least one property expressed in terms of an upper or lower time bound. This thesis investigates how DCTC business processes can be described such that the resulting model captures all the relevant aspects of each dimension of interest. In addition, the business model must be comprehensible to the stakeholders involved not only in its definition, but also in its further use throughout the software development life cycle.A revision and analysis of notations that exist for modelling business processes conducted in this thesis have revealed that today there does not exist any modelling language that provides comprehensible, suitable and sufficiently expressive support for the characteristics of dependability, collaboration and time in an integrated manner. Hence, a significant part of this thesis is devoted to the definition of a new business process modelling language named DT4BP. The aim of this new modelling language is to be comprehensible, suitable and expressive enough to describe DCTC business processes. The definition of this new modelling language implies that a concrete syntax, an abstract syntax, a semantic domain and a semantic mapping is provided. The definition of this new modelling language is given following the Model-Driven Engineering (MDE) approach, and in particular the metamodelling principles. Thus, meta-models and model transformations are used to precisely specify the abstract syntax and semantic mapping elements of the language definition, respectively. Since DT4BP is a textual modelling language, its concrete syntax is specified by a context-free grammar. The Coordinated Atomic Actions conceptual framework with real-time extensions (Timed-CaaFWrk) is used as the semantic domain as it covers a large part of the abstractions included in dependable collaborative time-constrained business processes. The formalisation of this semantic domain according to the metamodelling principles is also part of the material presented in this thesis. Since the business model is considered as a representation of the requirement document the software system to be developed, it is crucial to validate whether it captures the requirements as intended by the stakeholder before going further in the software development process. Hence, besides the comprehensibility, suitability and expressiveness of the modelling language with respect to the domain of interest, it is of special interest to provide a mechanism that allows modellers to ensure that the business model is correct with respect to the stakeholder's expectations. One way of achieving this goal is to provide the modelling language with an executable semantics. In this manner, any business model can be executed on sample input data, and its dynamic behaviour observed. The observation of the dynamic behaviour of the model may be considered as a simulation of the model based on the sample input data. By performing several simulations of the model, the modeller, in cooperation with the stakeholder, can judge whether the business model is correct. This thesis provides an executable semantics for Timed-CaaFWrk that, used in combination with the model transformation that defines the semantic mapping element of the language definition, allows DT4BP models to be validated by simulation. In this manner, the dynamic behaviour of a particular DT4BP model for a given sample input data can be observed by transforming it into a Timed-CaaFWrk model, which is then run thanks to the given executable semantics. [less ▲]

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See detailAdaptation cognitive et vieillissement : entre automatisme et flexibilité
Tournier, Isabelle UL

Doctoral thesis (2010)

L'objectif général de cette thèse est d'étudier l'évolution au cours du vieillissement des processus automatiques et contrôlés, nécessaires à une bonne adaptation cognitive quotidienne. Nous nous ... [more ▼]

L'objectif général de cette thèse est d'étudier l'évolution au cours du vieillissement des processus automatiques et contrôlés, nécessaires à une bonne adaptation cognitive quotidienne. Nous nous intéressons à l'influence de différentes variables cognitives (mémoire de travail, vitesse de traitement et vocabulaire) ainsi qu'aux préférences de routinisation sur l'expression de ce possible effet de l'âge. Des épreuves de fluidités sémantiques simples (Expérience 1) et alternées (Expériences 2 et 3) et des formats simples (Expériences 5a et 6a) et alternés (Expériences 5b et 6b) de la tâche de Hayling ont été réalisés par des adultes jeunes (18-30 ans), âgés (60-74 ans) et très âgés (75 ans et plus). Ces épreuves nous permettent d'étudier le processus automatique à travers la diffusion de l'activation en mémoire sémantique et les processus contrôlés par le biais de l'inhibition et de la flexibilité. L'activité cérébrale associée à l'exécution de fluidités simples et alternées est étudiée chez des participants âgés à l'aide de l'imagerie optique (Expérience 4). Les résultats obtenus sont en faveur d'une réduction avec l'âge de l'efficience des processus contrôlés alors que celle des processus automatiques semble conservée. Des phénomènes de compensation se mettraient en place au cours du vieillissement, s'appuyant sur les processus automatiques et les connaissances accumulées. [less ▲]

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See detailFunctions of hepatitis C virus non-structural protein 2
Dentzer, Thomas UL

Doctoral thesis (2010)

An estimated 170 million people are infected with hepatitis C virus (HCV). 15-30% of HCV-induced chronic hepatitis progresses to cirrhosis within years to decades after infection, and 3-4% of them will ... [more ▼]

An estimated 170 million people are infected with hepatitis C virus (HCV). 15-30% of HCV-induced chronic hepatitis progresses to cirrhosis within years to decades after infection, and 3-4% of them will develop hepatocellular carcinoma. There is no vaccine available, and current HCV therapy of pegylated interferon-! in combination with ribavirin leads to a sustained response only in about 50% of infected patients. The HCV non-structural protein NS2 (MW 23 kDa) is a dimeric multifunctional hydrophobic protein with an essential but poorly understood role in infectious virus production. The N terminal region of NS2 interacts with membranes whereas the Cterminal region, together with the N-terminal third of NS3, forms the NS2-3 protease. NS2 is not required for RNA synthesis, although cleavage at the NS2/3 junction is necessary for replication. Further, NS2 has been shown to interact with a number of viral and host proteins; it has been reported to activate transcription factors, inhibit apoptosis, and is a substrate for host kinase phosphorylation and proteosomic degradation. NS2 determinants and their respective function in the HCV life cycle were investigated. Based on the crystal structure of the post-cleavage form of the NS2 protease domain, we mutated conserved features and analyzed the effects of these changes on polyprotein processing, replication, and infectious virus production. We found that mutations around the protease active site inhibit viral RNA replication by preventing NS2/3 cleavage. Supplementary assays indicated a dimerization defect for these mutant constructs, which prevented cleavage and RNA replication. In contrast, alterations in the dimer interface and at the C-terminal region did not affect replication, NS2 stability, or NS2 protease activity, but decreased infectious virus production. Analysis of the NS2/3 cleavage site revealed an additional function for several residues besides cleavage, notably in infectious virus production. A more comprehensive deletion and mutagenesis analysis of the C-terminal end of NS2 revealed the importance of its C-terminal residue in infectious particle production. Structural data suggests that the C-terminal leucine is locked in the active site, and mutation or deletion of this residue could therefore alter the NS2 folding and disrupt potential protein-protein interactions important for infectious particle production. Further, we established an NS2- 3 interaction model based on the solved NS2pro and NS3 crystal structures and assessed the importance of proximal residues for viral propagation. We were able to show genetic interactions between the viral proteins NS2 and E1 as well as NS2 and NS3. Additionally a pull down assay of strep-tagged NS2 followed by a mass spectrometry analysis divulged the physical interactions between NS2-E2, and NS2- NS3. Numerous host cell proteins could be identified to interact with NS2, involved in various pathways such as membrane trafficking, actin/myosin interactions or actin polymerization. In this study we dissected the residues of NS2 involved in its multiple essential roles and interactions in the HCV life cycle and established NS2 as a new viable target for HCV-specific inhibitors for future anti-viral therapeutics. [less ▲]

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