Thermodynamics of a collapsing shell in an expanding Universe
  We describe the quasi-static collapse of a radiating, spherical shell of matter in de Sitter space-time using a thermodynamical formalism. It is found that the specific heat at constant area and other thermodynamical quantities exhibit singularities related to phase transitions during the collapse. 
G.L. Alberghi, R. Casadio and G.Venturi