Classical dynamics on three dimensional fuzzy space: Connecting the short and long length scales

We derive the path integral action for a particle moving in three dimensional fuzzy space. From this we extract the classical equations of motion. These equations have rather surprising and unconventional features: They predict a cut-off in energy, a generally spatial dependent limiting speed, orbital precession remarkably similar to the general relativistic result, flat velocity curves below a length scale determined by the limiting velocity and included mass, displaced planar motion and the existence of two dynamical branches of which only one reduces to Newtonian dynamics in the commutative limit. These features place strong constraints on the non-commutative parameter and coordinate algebra to avoid conflict with observation and may provide a stringent observational test for this scenario of non-commutativity.Comment: 21 pages, 4 figure

The Meissner effect for weakly isolated horizons

Black holes are important astrophysical objects describing an end state of stellar evolution, which are observed frequently. There are theoretical predictions that Kerr black holes with high spins expel magnetic fields. However, Kerr black holes are pure vacuum solutions, which do not include accretion disks, and additionally previous investigations are mainly limited to weak magnetic fields. We prove for the first time in full general relativity that generic rapidly spinning black holes including those deformed by accretion disks still expel even strong magnetic fields. Analogously to a similar property of superconductors, this is called Meissner effect.Comment: 7 pages, 4 figure

EU Democracy Promotion in the European Neighborhood: Conditionality, Economic Development, and Linkage.

[From the introduction]. Enlargement is often called the most successful foreign policy of the European Union (EU). The attractiveness of EU membership and the strict conditionality attached to the accession process have vested the EU with considerable transformative power in the applicant countries (Grabbe 2005; Schimmelfennig and Sedelmeier 2005). After the breakdown of Soviet communism and hegemony in Eastern Europe, enlargement has been credited with having contributed significantly to economic recovery, peace and stability as well as democratization in the transition countries of the region. With the accession of Bulgaria and Romania in January 2007, the Fifth Enlargement of the EU has been completed. Whereas the Western Balkans and Turkey continue to have a membership perspective, the EU has devised the European Neighborhood Policy (ENP) for the remaining countries of Eastern Europe and the Mediterranean as an alternative to accession. It remains to be seen, however, whether ENP will be able to produce similarly positive effects as enlargement. This policy question provides the practical interest we have in this paper....In this paper, we address these potential sources of bias and uncertainty. On the one hand, we systematically include in our analysis core variables of modernization theory as well as several proxies for diffuse international and transnational influences beyond the specific incentives of the EU. Second, we extend the study to 36 countries of the “European neighborhood” and thus to almost all post-communist and Mediterranean countries from the late 1980s to the beginning of the 21st century. Finally, in order to deal with this expanded data set, we move from comparative case studies to a panel regression analysis

Development of a task analysis tool to facilitate user interface design

A good user interface is one that facilitates the user in carrying out his task. Such interfaces are difficult and costly to produce. The most important aspect in producing a good interface is the ability to communicate to the software designers what the user's task is. The Task Analysis Tool is a system for cooperative task analysis and specification of the user interface requirements. This tool is intended to serve as a guide to development of initial prototypes for user feedback

The Weyl-Heisenberg Group on the Noncommutative Two-Torus: A Zoo of Representations

In order to assess possible observable effects of noncommutativity in deformations of quantum mechanics, all irreducible representations of the noncommutative Heisenberg algebra and Weyl-Heisenberg group on the two-torus are constructed. This analysis extends the well known situation for the noncommutative torus based on the algebra of the noncommuting position operators only. When considering the dynamics of a free particle for any of the identified representations, no observable effect of noncommutativity is implied.Comment: 24 pages, no figure