  We present molecular dynamics simulations of a model glass-forming liquid
(the binary Kob-Anderson Lennard-Jones model) and consider the distributions of
inherent energies and metabasins during aging. In addition to the typical
protocol of performing a temperature jump from a high temperature to a low
destination temperature, we consider the temporal evolution of the
distributions after an 'up-jump', i.e. from a low to a high temperature. In
this case the distribution of megabasin energies exhibits a transient two-peak
structure. Our results can qualitatively be rationalized in terms of a trap
model with a Gaussian distribution of trap energies. The analysis is performed
for different system sizes. A detailed comparison with the trap model is
possible only for a small system because of major averging effects for larger
systems.
