  In this paper we investigate the conformation statistics of a Gaussian chain
embedded in a medium of finite size, in the presence of quenched random
obstacles. The similarities and differences between the case of random
obstacles and the case of a Gaussian random potential are elucidated. The
connection with the density of states of electrons in a metal with random
repulsive impurities of finite range is discussed. We also interpret the
results obtained in some previous numerical simulations.
