Cloud computing has brought great benefits in cost and flexibility for provisioning services. The greatest challenge of cloud computing remains however the question of security. The current standard tools in access control mechanisms and cryptography can only partly solve the security challenges of cloud infrastructures. In the recent years of research in security and cryptography, novel mechanisms, protocols and algorithms have emerged that offer new ways to create secure services atop cloud infrastructures. This report provides introductions to a selection of security mechanisms that were part of the "Cloud Security Mechanisms" seminar in summer term 2013 at HPI. / Cloud Computing hat deutliche Kostenersparnisse und verbesserte Flexibilität bei der Bereitstellung von Computer-Diensten ermöglicht. Allerdings bleiben Sicherheitsbedenken die größte Herausforderung bei der Nutzung von Cloud-Diensten. Die etablierten Mechanismen für Zugriffskontrolle und Verschlüsselungstechnik können die Herausforderungen und Probleme der Sicherheit von Cloud-Infrastrukturen nur teilweise lösen. In den letzten Jahren hat die Forschung jedoch neue Mechanismen, Protokolle und Algorithmen hervorgebracht, welche neue Möglichkeiten eröffnen die Sicherheit von Cloud-Anwendungen zu erhöhen. Dieser technische Bericht bietet Einführungen zu einigen dieser Mechanismen, welche im Seminar "Cloud Security Mechanisms" im Sommersemester 2013 am HPI behandelt wurden.

Jacobi equations constitute a set of nonlinear partial differential equations which arise from the implementation in an arbitrary system of coordinates of a Poisson structure defined on a finite-dimensional smooth manifold. Certain skew-symmetric solutions of such equations are investigated in this dissertation. This is done from a twofold perspective including both the determination of new solution families as well as the construction of new global Darboux analyses of Poisson structures. The most general results investigated refer to the case of solutions of arbitrary dimension. The perspective thus obtained is of interest in view of the relatively modest number of solution families of this kind reported in the literature. In addition, the global Darboux analysis of structure matrices deals, in first place, with the global determination of complete sets of functionally independent distinguished invariants, thus providing a global description of the symplectic structure of phase space of any associated Poisson system; and secondly, with the constructive and global determination of the Darboux canonical form. Such kind of analysis is of interest because the construction of the Darboux coordinates is a task only known for a limited sample of Poisson structures and, in addition, the fact of globally performing such reduction improves the scope of Darboux' theorem, which only guarantees in principle the local existence of the Darboux coordinates. In this work, such reductions sometimes make use of time reparametrizations, thus in agreement with the usual definitions of system equivalence. In fact, time reparametrizations play a significant role in the understanding of the conditions under which the Darboux canonical form can be globally implemented, a question also investigated in detail in this dissertation. The implications of such results in connection with integrability issues are also considered in this context. The dissertation is structured as follows. Chapter 1 is devoted to the revision of diverse classical and well-known results that describe the basic framework of the investigation. The original contributions of the thesis are included in Chapters 2 to 4. Finally, the work ends in Chapter 5 with the presentation of some conclusions.

La problemática del cambio techno-tipológico durante el Paleolítico Medio es una cuestión debatida y no resuelta en los estudios de los comportamientos técnicos de los neandertales. El proyecto de esta tesis de doctorado tiene como objetivo contribuir a la discusión en curso añadiendo nuevos datos de dos yacimientos claves Europeos, Abric Romaní (España) (nivel O y M), y la Cueva de Fumane (Italia) (unidad A9 y A5+A6). El trabajo está enfocado en el cambio entre la tecnología Levallois y discoide, que ocurre en las secuencias arqueológicas de los dos yacimientos durante el MIS3. El estudio se ha llevado a cabo desde una perspectiva cuantitativa, teniendo en consideración los conceptos de Human Behavioral Ecology y los aspectos de costes y beneficios relacionados con el cambio de las estrategias de talla. / The problematic of the techno-typological change during the Middle Paleolithic is a debated and unresolved issue in the study of Neanderthals technical behaviors. The project of this Ph.D. thesis aims to contribute to the on-going discussion adding new data from two European key sites, Abric Romaní (Spain) (level O and M), and Fumane Cave (Italy) (unit A9 and unit A5+A6). The work is focused on the particular shift between Levallois and discoid technology that occurred in the archaeological sequences of the two sites during the MIS3. The study will be carried out with a quantitative perspective taking in considerations the concepts of the Human Behavioral Ecology and the aspects of costs and benefits related with the change of the knapping strategies

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This cross-sectional postal survey explores the relationship between musculoskeletal painand level of education in Ullensaker municipality. We used a Standard Nordic Questionnaire(SNQ) to register self-reported musculoskeletal pain in 3325 persons in 2004 (participationrate 55 %). We registered educational level and a series of other demographic and life-stylevariables as well as functional ability and subjective health complaints. We found in thisstudy that educational level and musculoskeletal pain is associated. People with loweducational levels are prone to have more musculoskeletal pain than persons with highereducation. When it comes to musculoskeletal pain that is limiting persons in their daily tasksthe difference is even larger between persons with low educational level and persons withhigher education / I en postal tverrsnittstudie har vi undersøkt forholdet mellom muskelsmerter ogutdanningsnivå i Ullensaker kommune. Vi brukte et standardisert spørreskjema ommuskelsmerter (også kalt Ørebro-skjemaet) og fikk svar fra 3325 personer (svarprosent55%). Vi registrerte utdanningsnivå og en rekke andre demografiske- og livsstilsvariablesamt funksjonsevne og subjektive helseplager. Vi fant i denne studien ensammenheng mellom utdanningsnivå og muskelsmerter. Personer med lavtutdanningsnivå har mer muskelsmerter enn personer med høyere utdanning. Når detgjelder å bli hindret i sine daglige aktiviteter av smertene er forskjellene enda størremellom de med lav utdanning og de med høy utdanning / <p>ISBN 978-91-85721-43-6</p>

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In this thesis we use the GARCH(1,1) and GJR-GARCH(1,1) models to estimate the conditional variance for five equities from the OMX Nasdaq Stockholm (OMXS) stock exchange. We predict 95% and 99% Value-at-Risk (VaR) using one-day ahead forecasts, under three different error distribution assumptions, the Normal, Student’s t and the General Error Distribution. A 500 observations rolling forecast-window is used on the dataset of daily returns from 2007 to 2014. The empirical size VaR is evaluated using the Kupiec’s test of unconditional coverage and Christoffersen’s test of independence in order to provide the most statistically fit model. The results are ultimately filtered to correspond with the Basel (II) Accord Penalty Zones to present the preferred models. The study finds that the GARCH(1,1) is the preferred model when predicting the 99% VaR under varying distribution assumptions.

This thesis contributes to the under-researched field of political selection, namely one’s re-selection onto the party list after one has been elected in the previous term. The theoretical rationale is to introduce a broader concept of political selection to a field mostly focused on political recruitment, one’s first point of entry into Politics. We show that the framework developed to study political recruitment can be adapted to study any kind of political selection that involves a broad pool of aspirants from which successful candidates must be selected. To this end, we utilise a panel dataset containing data on 387 Czech legislators covering the period between 1996 and 2013. Using fixed- and random-effects panel models, we show that voting along the party line and preferential vote share at time t are strong predictors of getting a better party-list rank at t+1. Legislative experience, however, is negatively associated with how well one fares at the re-selection process. We also provide evidence that it is left-wing parties rather than their right-wing counterparts that discriminate against women at the re-selection stage. The study thus contributes, directly or otherwise, to debates on women’s representation, political careers and re-election.

This paper analyzes the effect of political and economic factors on the risk of regime change in countries between 1975 and 2010, using survival analysis with time-dependent covariates. The findings show that negative economic growth increases the risk of regime change in the following year, and that a higher level of GDP per Capita, as well as international trade, has an inhibiting effect on the risk of regime change in democracies. The results also show that countries with young regimes are more likely to experience a regime change, and that countries with a long tradition of democratic governance suffer virtually no risk of experiencing a regime failure. These findings lend heavy support to the democratic consolidation theory, while giving mixed support to other theories of economic and political causes of regime change. The more generalized approach to regime change used in this paper provides a stepping stone for opening up a greater understanding of the mechanisms which cause regime change in all types of governments, and regardless of the direction of the change in relation to democracy.