  Continuing the discussion on negative entropy in Casimir-effect like
configurations, we consider two simple one-dimensional examples. One is the
s-wave contribution to a plasma sphere and the other a single delta function
potential. Some information on generic background potential is gained applying
Levinson's theorem. For the first example we find negative entropy. The
one-dimensional examples are especially interesting as these do not require the
subtraction of contributions growing with temperature faster than the classical
limit.
