Studies of the influence of electromagnetic effects on turbulent transport in fusion plasmas have been carried out using GEM, a “delta-f” type particle-in-cell code for turbulence simulations which include kinetic electron dynamics and electromagnetic perturbations (Y. Chen and S.E. Parker, Journal of Comp. Phys. 189, 463 (2003)). This code has been recently extended to handle general toroidal equilibrium magnetic field configurations (Y. Chen and S.E. Parker, submitted to Journal of Comp. Phys.). In this presentation we will report on new results of applying the GEM code to the analysis of transport properties observed in the National Spherical Torus Experiment (NSTX). Linear simulations from GEM indicate that electromagnetic modes, such as the Kinetic Ballooning Modes or modes with tearing mode parity, can be unstable at the high beta values of NSTX plasmas. The small size of the device (minor radius about tens of ion Larmor radii) and the strongly shaped magnetic flux surfaces make it impossible to accurately capture the unstable mode structure in the simple flux-tube geometry based on the local approximation. We will also report new results from nonlinear simulations and make comparisons with experimental observations. With respect to verification/validation considerations, the gyrokinetic model used in the GEM code has previously been shown to recover the MHD equation for the shear Alfven modes, including the prominent Toroidicity-induced-Alfven-Eigenmdes (TAE), which are expected to be relevant to ITER. It is of great interest to study the linear stability of TAEs with a self-consistent, non-perturbative treatment of various damping mechanisms such as continuum damping and radiative damping. Progress and associated physics insights gained in this area will also be reported.