My work is centered on particle acceleration, magnetic field generation, and the associated radiation from gamma-ray bursts (GRBs) and Active Galactic Nuclei (AGN). The GRB are thought to be associated with the most energetic explosions in the Universe and the AGN are associated with massive black holes at the center of galaxies. Along with national and international collaborators, I am investigating both macroscopic magnetohydrodynamic (MHD) processes and microscopic plasma processes associated with the relativistic jets that are thought to account for the properties of GRB and AGN emission. In particular, we are studying the processes associated with velocity shears, internal and external shocks, and magnetic reconnection that should be associated with the relativistic jets. Our research studies use both 3-D relativistic MHD (RMHD) and 3-D relativistic particle-in-cell (RPIC) numerical simulations. Internal and external shocks are currently the leading models for interpreting the observed spectra and light curves associated with GRB prompt and afterglow emission. Internal shocks are currently the leading model for the Blazars associated with relativistic AGN jets viewed nearly along the line of sight. Additional current interests are the GRB relation to the stellar progenitor and host environment, including the collapsar/supernova scenario, the production mechanisms of X-ray lines and continuum, electron-positron-proton jet composition, jet structure and collimation, the role of ultra-high (> TeV) energy neutrinos and GeV-TeV photons from GRBs and AGN. The following link gives a snapshot view of Gamma-Ray Astrophysics Team (the Fermi GRB, X-Ray Astronomy, Solar Physics Group, and Space Plasma Physics Group at NSSTC. Past and current NSF Astrophysics and NASA ATP awards support our investigation of the microscopic and macroscopic processes associated with jet formation, propagation and radiation using general relativistic MHD (GRMHD), RMHD and RPIC simulations. A brief overview of the main research areas and some details related to specific projects can be found under the links to gamma-ray bursts, RMHD simulations of relativistic jets, RPIC simulations of particle acceleration, and Magnetospheric plasmas.