Michael Levitin
michaellevitin.net
Spectra of Dirichlet-to-Neumann maps
The scripts for the paper Spectral properties of the Dirichlet-to-Neumann map for the Helmholtz equation (with Denis S. Grebenkov and Iosif Polterovich)
Eigenvalue curves for DtN maps for cuboids
Mathematica notebook
pdf printout of the Mathematica notebook (for those without access to Mathematica)