Level dynamics in pseudointegrable billiards: an experimental study
  The level dynamics of pseudointegrable systems with different genus numbers $g$ is studied experimentally using microwave cavities. For higher energies the distribution of the eigenvalue velocities is Gaussian, as it is expected for chaotic systems with time-reversal symmetry, and shows no dependence on $g$. Also the curvature distribution $P(k)$ for large $k$ is decaying as it is expected for chaotic systems, i.e. $P(k) \sim |k|^{-3}$. For small $k$ an intermediate behavior is found, where $P(k)$ changes from integrable towards chaotic behavior with growing $g$. 
Yuriy Hlushchuk, Ulrich Kuhl, Stefanie Russ