  Recent studies show the importance of feedback in the evolution of the star
formation rate in the Universe. However, the nature and physics of the feedback
are still pressing questions. Radio continuum observations can provide unique
dust-unbiased tracers of massive star formation and of the interstellar medium
(ISM) and hence are ideal to address the regulation of star formation in
galaxies. Our multi-frequency and multi-resolution radio surveys in nearby
galaxies enable us to trace various phases of star formation and dissect the
thermal and nonthermal ISM in galaxies. Mapping the cosmic ray electron energy
index and magnetic field strength, we have found observational evidence that
massive star formation significantly affects the energy balance in the ISM
through the injection and acceleration of cosmic rays and the amplification of
magnetic fields. How the next generation of stars could form in such a
magnetized and turbulent ISM will be addressed in our 'EVLA cloud-scale survey
of the local group galaxy M33' and in forthcoming surveys with the SKA.
