The difficult early stages of embedded star clusters and the importance
  of the pre-gas expulsion virial ratio
  We examine the effects of gas-expulsion on initially substructured
distributions of stars. We perform N-body simulations of the evolution of these
distributions in a static background potential to mimic the gas. We remove the
static potential instantaneously to model gas-expulsion. We find that the exact
dynamical state of the cluster plays a very strong role in affecting a
cluster's survival, especially at early times: they may be entirely destroyed
or only weakly affected. We show that knowing both detailed dynamics and
relative star-gas distributions can provide a good estimate of the post-gas
expulsion state of the cluster, but even knowing these is not an absolute way
of determining the survival or otherwise of the cluster.
