  The BRAHMS experiment at RHIC has measured the production of charged hadrons
as a function of pseudorapidity and transverse momentum in Au+Au, d+Au and p+p
collisions at a common energy of sqrt(s_NN)=200GeV, and from these spectra we
construct the nuclear modification factors for both ``hot'' and ``cold''
nuclear matter. In this contribution I will show how these factors evolve with
pseudorapidity and collision centrality. We see a Cronin-like enhancement in
d+Au collisions at midrapidity, going to a strong suppression at eta >= 2. In
central Au+Au collisions we find a suppression both at mid- and forward
rapidities that vanishes for peripheral collisions. We interpret this as signs
of several different medium related effects modifying bulk particle production
in Au+Au and d+Au collisions at RHIC energies.
