The interaction of high energy photons with matter: ionization, bremsstrahlung, Compton scattering, electron-positron pair production, Cerenkov radiation; photon spectra resulting from these processes; nuclear interactions, cosmic rays and their interactions in the atmosphere; dynamics and diffusion of charged particles in magnetic fields, synchrotron radiation, magnetic flux pinning, magnetic diffusion; gases and magnetic fields in the nterstellar medium, acceleartion mechanisms for charged particles, the energy spectra of electrons, protons and nuclei in the Galaxy.