  Many biological regulatory systems process signals out of steady state and
respond with a physiological delay. A simple model of regulation which respects
these features shows how the ability of a delayed output to transmit
information is limited: at short times by the timescale of the dynamic input,
at long times by that of the dynamic output. We find that topologies of
maximally informative networks correspond to commonly occurring biological
circuits linked to stress response and that circuits functioning out of steady
state may exploit absorbing states to transmit information optimally.
