The Interstellar Medium and star formation on kpc size scales
  By resimulating a region of a global disc simulation at higher resolution, we
resolve and study the properties of molecular clouds with a range of masses
from a few 100's M$_{\odot}$ to $10^6$ M$_{\odot}$. The purpose of our paper is
twofold, i) to compare the ISM and GMCs at much higher resolution compared to
previous global simulations, and ii) to investigate smaller clouds and
characteristics such as the internal properties of GMCs which cannot be
resolved in galactic simulations. We confirm the robustness of cloud properties
seen in previous galactic simulations, and that these properties extend to
lower mass clouds, though we caution that velocity dispersions may not be
measured correctly in poorly resolved clouds. We find that the properties of
the clouds and ISM are only weakly dependent on the details of local stellar
feedback, although stellar feedback is important to produce realistic star
formation rates and agreement with the Schmidt-Kennicutt relation. We study
internal properties of GMCs resolved by $10^4-10^5$ particles. The clouds are
highly structured, but we find clouds have a velocity dispersion radius
relationship which overall agrees with the Larson relation. The GMCs show
evidence of multiple episodes of star formation, with holes corresponding to
previous feedback events and dense regions likely to imminently form stars. Our
simulations show clearly long filaments, which are seen predominantly in the
inter-arm regions, and shells.
