A single-frequency test for one-parameter models of the linear   thermo-visco-elastic response of glass-forming liquids
  A master equation description of the inherent dynamics is used to calculate the frequency-dependent linear thermo-visco-elastic response functions of a glass-forming liquid. From the imaginary parts of the isobaric specific heat, isothermal bulk modulus, and isobaric thermal expansion coefficient, we define a quantity $\Lambda_{Tp}(\omega)$ with the property that $\Lambda_{Tp}(\omega)=1$ is equivalent to having a one-parameter description of the linear thermo-visco-elastic response. This provides an alternative to the well-known criterion based on the Prigogine-Defay ratio. 
N. L. Ellegaard, T. Christensen, N. B. Olsen, and J. C. Dyre