Critical numbers of attractive Bose-condensed atoms in asymmetric traps
  The recent Bose-Einstein condensation of ultracold atoms with attractive interactions led us to consider the novel possibility to probe the stability of its ground state in arbitrary three-dimensional harmonic traps. We performed a quantitative analysis of the critical number of atoms through a full numerical solution of the mean field Gross-Pitaevskii equation. Characteristic limits are obtained for reductions from three to two and one dimensions, in perfect cylindrical symmetries as well as in deformed ones. 
A. Gammal, L. Tomio, T. Frederico