A Test of the Particle Paradigm in N-Body Simulations
  We present results of tests of the evolution of small ``fluid elements'' in cosmological N--body simulations, to examine the validity of their treatment as particles. We find that even very small elements typically collapse along one axis while expanding along another, often to twice or more their initial comoving diameter. This represents a possible problem for high--resolution uses of such simulations. 
B. Kuhlman, A.L. Melott, and S.F. Shandarin