Agentenbasierende Finanzmarktmodelle

In this thesis we look at different models of financial markets whose dynamic is based on the herding behaviour of the agents trading on the market. Kirman introduced the first model of this kind in the year 1991. We also consider another model that is introduced by Alfarano et al. in the year 2007. The basic assumptions of these models are that there is a fixed number of agents N, who trade on the market. These agents can be divided into two groups. We call them optimists and pessimists. The dynamic of these models is based on the fact that the agents switch between the two groups. Important for the state of the system is not the membership of each agent in one of the groups but the relation between optimistic and pessimistic agents. Due to the fact that the number of agents is constant, it is sufficient to look at the number of optimistic agents. In the two models mentioned above, the number of optimistic agents is modelled as a birth and death process. At first, we look at the behaviour of these birth and death processes in the case that the number of agents N tends to infinity. After that, we extend the model with another agent, representing further influences for the behaviour of the optimists and pessimists whom we call “super agent” and look at different limiting cases for this new model.In dieser Arbeit betrachten wir verschiedene Finanzmarktmodelle, deren Dynamik auf dem Kommunikationsverhalten der am Markt handelnden Agenten basiert. Das erste Modell dieser Art hat der Ökonom Kirman im Jahr 1991 beschrieben. Ein weiteres Modell, das wir betrachten, stammt aus einem Artikel von Alfarano et al. Aus dem Jahr 2007. Die Modelle basieren im Wesentlichen auf den folgenden Annahmen: Es gibt eine feste Anzahl Agenten N, die am Markt handeln. Diese Agenten lassen sich in zwei Gruppen aufteilen. Diese Gruppen werden wir als Optimisten und Pessimisten bezeichnen. Die Dynamik des Modells entsteht daraus, dass die Agenten zwischen diesen beiden Gruppen hin und her wechseln. In den beiden oben genannten Modellen wird die Dynamik des Modells durch einen Geburts- und Todesprozess modelliert. Zunächst betrachten wir das Verhalten dieser Geburts- und Todesprozesse für den Fall betrachten, dass die Anzahl der Agenten N gegen unendlich strebt. Danach erweitern wir das Modell und betrachten verschiedene Grenzverhalten im erweiterten Modell

A statistical equilibrium model of competitive firms

We find that the empirical density of firm profit rates, measured as returns on assets, is markedly non-Gaussian and reasonably well described by an exponential power (or Subbotin) distribution. We start from a statistical equilibrium model that leads to a stationary Subbotin density in the presence of complex interactions among competitive heterogeneous firms. To investigate the dynamics of firm profitability, we construct a diffusion process that has the Subbotin distribution as its stationary probability density. This leads to a phenomenologically inspired interpretation of variations in the shape parameter of the Subbotin distribution, which essentially measures the competitive pressure in and across industries. Our findings have profound implications both for the previous literature on the ‘persistence of profits’ as well as for understanding competition as a dynamic process. Our main formal finding is that firms' idiosyncratic efforts and the tendency for competition to equalize profit rates are two sides of the same coin, and that a ratio of these two effects ultimately determines the dispersion of the equilibrium distribution

2019 Proceedings of the 2nd International Conference on Trauma Surgery Technology in Giessen (Germany)

It is now for a second time that we can invite researchers to come to Giessen for an international exchange of the latest research and a discussion of ideas. This year again, the Deutsche Forschungsgemeinschaft (DFG) is sponsoring the event. The main topic for 2019 is 'Vibration in antibacterial and oncological therapy'. Many effects of mechanical vibration on tissue have been discovered so far. Clinical applications relying on vibration exist for a variety of conditions. The intracellular processes, however, are still largely not understood. And reproducibility remains a matter of potential for improvement. DFG funds for the 3rd conference in 2020 have already been approved for a focus on multifunctional trauma surgery implants.Deutsche Forschungsgemeischaft (DFG), German

Accession Incentives for Institutional Change in Post-Socialist Countries – Cross-Section and Country Evidence from NATO Enlargement

This paper analyses the transformative power of NATO accession that gains in importance due to the enlargement fatigue of the EU, the EU’s rather weak neighbourhood incentives and the increasing importance of regional security as an incentive for compliance with the institutional standards of democracy and market economy. Econometric cross-country evidence from a hazard model reveals that the entry into NATO’s accession process is mainly driven by neighbourhood and strategic effects rather than foregoing institutional reforms in a candidate-country. While strategic interests also dominated the accession process of Macedonia initially, the case study results reveal the central role of the switch in NATO’s strategy from strategic interest only to a more balanced consideration of institutional reforms, which ‘turned Macedonia around’ in terms of institutional development. Clearly, after this turning point marked by the Ohrid agreement, the effectiveness of NATO’s accession conditionality could be revealed. The switch in NATO’s strategy, rather enforced externally than the result of a well structured debate among NATO members, is of special relevance for the peaceful transition of other post-socialist countries, e.g. Ukraine and GeorgiaNATO Enlargement, Democratization, Institutions, Transition, Conflict, FYR Macedonia

SWITCHING RATES AND THE ASYMPTOTIC BEHAVIOR OF HERDING MODELS

Markov chains have experienced a surge of economic interest in the form of behavioral agent-based models that aim at explaining the statistical regularities of financial returns. We review some of the relevant mathematical facts and show how they apply to agent-based herding models, with the particular goal of establishing their asymptotic behavior since several studies have pointed out that the ability of such models to reproduce the stylized facts hinges crucially on the size of the agent population (typically denoted by N), a phenomenon that is also known as N-dependence. Our main finding is that N-(in)dependence traces back to both the topology and the velocity of information transmission among heterogeneous financial agents.Markov chains, agent-based finance, herding, N-dependence, JEL Code: C10, JEL Code: D84, JEL Code: D85, JEL Code: G19, 02.50.Ga, 89.65.Gh

Switching Rates and the Asymptotic Behavior of Herding Models

Markov chains have experienced a surge of economic interest in the form of behavioral agent-based models that aim at explaining the statistical regularities of financial returns. We review some of the relevant mathematical facts and show how they apply to agent-based herding models, with the particular goal of establishing their asymptotic behavior because several studies have pointed out that the ability of such models to reproduce the stylized facts hinges crucially on the size of the agent population (typically denoted by n), a phenomenon that is also known as n-dependence. Our main finding is that n-(in)dependence traces back to both the topology and the velocity of information transmission among heterogeneous financial agentsMarkov chains, agent-based finance, herding, N-dependence

Spektrum Patholinguistik Band 14. Schwerpunktthema: Klick für Klick: Schritte in der digitalen Sprachtherapie

The Fourteenth Autumn Meeting Patholinguistics with its main topic »Click by click: Steps towards a digital speech/language therapy« took place online on the 14th of November 2020. This annual meeting has been organised since 2007 by the Association for Patholinguistics (vpl) in cooperation with the German Federal Association for Academic Speech/Language Therapy and Logopaedics (dbs) and the University of Potsdam. The present proceedings feature the keynote presentations on the main topic as well as articles from the poster session covering a broad range of areas in research and practice of speech/language therapy.Das 14. Herbsttreffen Patholinguistik mit dem Schwerpunktthema »Klick für Klick: Schritte in der digitalen Sprachtherapie« fand am 14.11.2020 als Online-Veranstaltung statt. Das Herbsttreffen wird seit 2007 jährlich vom Verband für Patholinguistik e.V. (vpl) in Kooperation mit dem Deutschen Bundesverband für akademische Sprachtherapie und Logopädie (dbs) und der Universität Potsdam durchgeführt. Der vorliegende Tagungsband beinhaltet die Hauptvorträge zum Schwerpunktthema sowie die Posterpräsentationen zu weiteren Themen aus der sprachtherapeutischen Forschung und Praxis