Observational and theoretical cosmology (dark energy, dark matter, modified gravity, inflation, neutrinos, etc.), cosmological probes (galaxy cluster mass function, cluster gas-mass fraction, redshifted hyperfine 21-cm transition from neutral hydrogen, cosmic microwave background, supernovae, clustering of galaxies and clusters, baryon acoustic oscillations, etc.), first stars, galaxies and black holes, and epoch of reionization, cluster astrophysics and observable-mass scaling relations, Bayesian statistics and inference.