Phase Transition in Pulsar Timing
  A phase transition in the nature of matter in the core of a neutron star, such as quark deconfinement or Bose condensation, can cause the spontaneous spin-up of a solitary millisecond pulsar. The spin-up epoch for our model lasts for $2\times 10^7$ years or 1/50 of the spin-down time (Glendenning, Pei and Weber in Ref. \cite{glen97:a}). The possibility exists also for future measurements on X-ray neutron stars with low-mass companions for mapping out the tell-tale ``backbending'' behavior of the moment of inertia. Properties of phase transitions in substances such as neutron star matter, which have more than one conserved charge, are reviewed. 
Norman K. Glendenning (Nuclear Science Division & Institute for   Nuclear and Particle Astrophysics, Lawrence Berkeley Natio...