Mode fluctuations as fingerprint of chaotic and non-chaotic systems

The mode-fluctuation distribution $P(W)$ is studied for chaotic as well as for non-chaotic quantum billiards. This statistic is discussed in the broader framework of the $E(k,L)$ functions being the probability of finding $k$ energy levels in a randomly chosen interval of length $L$, and the distribution of $n(L)$, where $n(L)$ is the number of levels in such an interval, and their cumulants $c_k(L)$. It is demonstrated that the cumulants provide a possible measure for the distinction between chaotic and non-chaotic systems. The vanishing of the normalized cumulants $C_k$, $k\geq 3$, implies a Gaussian behaviour of $P(W)$, which is realized in the case of chaotic systems, whereas non-chaotic systems display non-vanishing values for these cumulants leading to a non-Gaussian behaviour of $P(W)$. For some integrable systems there exist rigorous proofs of the non-Gaussian behaviour which are also discussed. Our numerical results and the rigorous results for integrable systems suggest that a clear fingerprint of chaotic systems is provided by a Gaussian distribution of the mode-fluctuation distribution $P(W)$.Comment: 44 pages, Postscript. The figures are included in low resolution only. A full version is available at http://www.physik.uni-ulm.de/theo/qc/baecker.htm

Die Schweizer Gemeinden im Wandel : Konvergenz oder Divergenz?

Switzerland is currently going through a phase of political restructuring. The numerous reform activities at the beginning of the twenty-first century leave almost no area of political life untouched. The reforms are particularly abundant in the 2′867 municipalities, spanning from amalgamations, intermunicipal co-operation, New Public Management, to reforms of the political systems. Accounting for the fact that there are big socio-economic differences between the municipalities as well as their political systems, we investigate whether the municipalities are headed for divergence or convergence as a result of these reforms. The empirical results are derived from three surveys of the local authorities conducted in 1988, 1994, and 1998. The results indicate that the communes do convergence in regard to their administrative and political structure. However, the convergence appears to be limited to the single cantons and observable only among certain types of municipalities

The equation of state of neutron matter, symmetry energy, and neutron star structure

We review the calculation of the equation of state of pure neutron matter using quantum Monte Carlo (QMC) methods. QMC algorithms permit the study of many-body nuclear systems using realistic two- and three-body forces in a nonperturbative framework. We present the results for the equation of state of neutron matter, and focus on the role of three-neutron forces at supranuclear density. We discuss the correlation between the symmetry energy, the neutron star radius and the symmetry energy. We also combine QMC and theoretical models of the three-nucleon interactions, and recent neutron star observations to constrain the value of the symmetry energy and its density dependence.Comment: 11 pages, 11 figure

Stellar archeology of the nearby LINER galaxies NGC 4579 and NGC 4736

Stellar archeology of nearby LINER galaxies may reveal if there is a stellar young population that may be responsible for the LINER phenomenon. We show results for the classical LINER galaxies NGC 4579 and NGC 4736 and find no evidence of such populations.Comment: 2 pages, 2 figures, to be published in the Proceedings of the IAU Symposium no. 26