It may be said that signal processing is the coin of the electronic realm, and here contributors examine topics as hyperbolic geometry, Nehari's theorem, electronic circuits and analog signal processing, engineering applications of the Motion-Group Fourier transform, fast x-ray and beamlet transforms for 3D data, Fourier analysis and phylogenetic trees, diverse tomography, matrix-valued spherical functions, image resolution for MRI, image compression, integrating sensing and processing for statistical pattern recognition, sampling of functions and sections for compact groups, the Cooley-Tukey FFT and group theory, signal processing in optic fibers, and the generalized spike process.