Speaker: Pasquale Blasi, Osservatorio Astrofisico di Arcetri (Florence, Italy)
Abstract: Present observations, especially in the gamma ray band, appear to confirm the need for source spectra of cosmic rays steeper than suggested by current theories. This trend is also required by observations of the anisotropy on large scales which in the TeV range is at the level of $sim 10^{-3}$ and appear to stay roughly constant with energy up to around the knee region. Steep spectra are very difficult to explain unless one invokes poorly understood effects in particle scattering or probably the presence of neutrals in the medium where the shock propagates. I will discuss these issues with particular emphasis on the process of particle acceleration in partially ionized media.