  Predictions of the existence of well-defined deeply bound pionic atom states
for heavy nuclei and the eventual observation of such states by the (d,3He)
reaction have revived interest in the pion-nucleus interaction at threshold and
in its relation to the corresponding pion-nucleon interaction. Explanation of
the 'anomalous' s-wave repulsion in terms of partial restoration of chiral
symmetry and/or in terms of energy-dependence effects have been tested in
global fits to pionic atom data and in a recent dedicated elastic scattering
experiment. The role of neutron density distributions in this context is
discussed in detail for the first time.
