Outlier Treatment and Robust Approaches for Modeling Electricity Spot Prices

We investigate the effects of outlier treatment on the estimation of the seasonal component and stochastic models in electricity markets. Typically, electricity spot prices exhibit features like seasonality, mean-reverting behavior, extreme volatility and the occurrence of jumps and spikes. Hence, an important issue in the estimation of stochastic models for electricity spot prices is the estimation of a component to deal with trends and seasonality in the data. Unfortunately, in regression analysis, classical estimation routines like OLS are very sensitive to extreme observations and outliers. Improved robustness of the model can be achieved by (a) cleaning the data with some reasonable procedure for outlier rejection, and then (b) using classical estimation and testing procedures on the remainder of the data. We examine the effects on model estimation for different treatment of extreme observations in particular on determining the number of outliers and descriptive statistics of the remaining series after replacement of the outliers. Our findings point out the substantial impact the treatment of extreme observations may have on these issues.Electricity; price modeling; seasonal decomposition; price spike

German Expellee Organizations between “Homeland” and “At Home”: A Case Study of the Politics of Belonging

Since the expulsion of more than ten million ethnic Germans from Central and Eastern Europe after the end of the Second World War, the political and cultural organizations of the expellees have advocated the interests of this segment of the Federal Republic’s population. The article examines the various ways in which activists in the expellee organizations have used the ambiguity of homeland and belonging in the political process in Germany and increasingly in Europe to further a political agenda that, while it has undergone major changes, remains deeply problematic in some of its objectives and many of its implications.Depuis l’expulsion de plus de 10 millions de personnes d’ethnie allemande d’Europe Centrale et d’Europe de l’Est après la fin de la deuxième Guerre mondiale, les organisations politiques et culturelles des expulsés ont milité en faveur de cette section de la population de la République Fédérale. L’article examine comment les activistes appartenant aux organisations des expulsés ont profité de l’ambiguïté entourant les concepts de patrie et d’appartenance dans le cadre des processus politiques en Allemagne et, de plus en plus, dans le reste de l’Europe, pour faire avancer un agenda politique qui, même s’il a connu des changements majeurs, reste toujours extrêmement problématique par rapport à certains de ses objectifs et plusieurs de ses implications

Design and implementation of a workflow for quality improvement of the metadata of scientific publications

In this paper, a detailed workflow for analyzing and improving the quality of metadata of scientific publications is presented and tested. The workflow was developed based on approaches from the literature. Frequently occurring types of errors from the literature were compiled and mapped to the data-quality dimensions most relevant for publication data – completeness, correctness, and consistency – and made measurable. Based on the identified data errors, a process for improving data quality was developed. This process includes parsing hidden data, correcting incorrectly formatted attribute values, enriching with external data, carrying out deduplication, and filtering erroneous records. The effectiveness of the workflow was confirmed in an exemplary application to publication data from Open Researcher and Contributor ID (ORCID), with 56\% of the identified data errors corrected. The workflow will be applied to publication data from other source systems in the future to further increase its performance

Banking and sovereign risk in the euro area

We study the determinants of sovereign bond spreads in the euro area since the introduction of the euro. We show that an aggregate risk factor is a main driver of spreads. This factor also plays an important indirect role for risk spreads through its interaction with the size and structure of national banking sectors. When aggregate risk increases, countries with large banking sectors and low equity ratios in the banking sector experience greater widening in yield spreads, suggesting that financial markets perceive a larger risk that governments will have to rescue banks, increasing public debt and therefore sovereign risk. Moreover, government debt levels and forecasts of future fiscal deficits are also significant determinants of sovereign spreads. --Sovereign bond markets,banking,liquidity,EMU

Dynamics of Open Quantum Systems

Remarkable experimental progress and theoretical advancements in the study of strongly corre- lated systems have opened up new doors towards a better understanding of interesting states of matter. Such states could possibly be used to develop novel technological applications based on the principles of quantum mechanics. In recent years, the investigation of both complex solid state and ultracold atom systems has lead to a number of fascinating discoveries with regards to their non-equilibrium properties. One route to probe non-equilibrium physics is to consider the evolution of open systems defined by the coupling to an external environment introducing dissipation. Engineering the environment according to predefined requirements can then be used to dynamically prepare states which are difficult to access otherwise. This thesis explores the dynamics of many-body open quantum systems aiming at under- standing the effects resulting from the interplay of kinetic motion, interactions and dissipation in different physical settings. First, we build upon recent developments concerning the coupling of ultracold atoms to optical resonators which are subject to photon losses. We show how the dissipation can trigger an attractor dynamics towards a topologically non-trivial steady state that is robust against perturbations. The numerically obtained full open system evolution en- ables us to not only characterize in detail the steady state but also to analyze the features of the approaching dynamics. Second, we study the propagation of two-time correlation functions in interacting quantum spin-1/2 chains in contact with an environment causing dephasing. Pro- vided with the numerically exact full time-evolution, we identify an algebraic scaling regime where time-translation invariance breaks down and uncover the emergence of aging dynam- ics. Finally, we study a system of interacting fermionic atoms in a one-dimensional lattice with particle loss at the central site. There we report on the dissipation-induced deceleration of the non-equilibrium dynamics known as the quantum Zeno effect. As in the majority of cases quantum many-body systems are not solvable analytically, another central aspect of this thesis deals with adapting numerical methods based on matrix product state algorithms to investigate open quantum systems dynamics