Microstructure of He II in the presence of boundaries
  We have studied the microstructure of a system of interacting Bose particles under zero boundary conditions and have found two possible orderings. One ordering is traditional and is characterized by the Bogolyubov dispersion law E^2 = (h^2 k^2/2m)^{2} + qn\nu(k)[h^2 k^2/m] (with q=1) at a weak interaction. The second one is new and is characterized by the same dispersion law, but with q=2^{-f}, where $f$ is the number of noncyclic coordinates. At a weak interaction, the ground-state energy is less for the new solution. The boundaries affect the bulk microstructure due to the difference of the topologies of closed and open systems. 
Maksim D. Tomchenko
cond-mat.other