  Data taken over the last several years have demonstrated that RHIC has
created a hot, dense medium with partonic degrees of freedom. Identified
particle spectra at high transverse momentum ($p_T$) and heavy flavor are
thought to be well calibrated probes thus serve as ideal tools to study the
properties of the medium. We present $p_T$ distributions of particle ratios in
p+p collisions from STAR experiment to understand the particle production
mechanisms. These measurements will also constrain fragmentation functions in
hadron-hardon collisions. In heavy ion collsions, we highlight: 1) recent
measurements of strange hadrons and heavy flavor decay electrons up to high
$p_T$ to study jet interaction with the medium and explore partonic energy loss
mechanisms; and 2) $\Upsilon$ and high $p_T$ $J/\psi$ measurements to study the
effect of color screening and other possible production mechanisms.
