  Nucleus-nucleus collisions at RHIC produce high temperature and high energy
density matter which exhibits partonic degrees of freedom. We will discuss
measurements of nuclear modification factors for light hadrons and non-photonic
electrons from heavy quark decays, which reflect the flavor dependence of
energy loss of high momentum partons traversing the dense QCD medium. The
hadronization of bulk partonic matter exhibits collectivity in effective
partonic degrees of freedom. Nuclear collisions at RHIC provide an intriguing
environment, where many constituent quark ingredients are readily available for
possible formation of exotic particles through quark coalescences or
recombinations.
