  The violations of the fluctuation-dissipation theorem are analyzed for a trap
model with a gausssian density of states. In this model, the system reaches
thermal equilibrium for long times after a quench to any finite temperature and
therefore all aging effect are of a transient nature. For not too long times
after the quench it is found that the so-called fluctuation-dissipation ratio
tends to a non-trivial limit, thus inicating the possibility for the definition
of a time scale dependent effective temperature. However, different definitions
of the effective temperature yield distinct results. In particular plots of the
integrated response versus the correlation function strongly depend on the way
they are constructed. Also the definition of effective temperatures in the
frequency domain is not unique for the model considered. This may have some
implications for the interpretation of results from computer simulations and
experimental determinations of effective temperatures.
