  The impact of uniaxial and hydrostatic stress on the ballistic thermal
conductance ($\kappa_{l}$) and the specific heat ($C_{v}$) of [100] and [110]
Si nanowires are explored using a Modified Valence Force Field phonon model. An
anisotropic behavior of $\kappa_{l}$ and isotropic nature of $C_{v}$ under
strain are predicted for the two wire orientations. Compressive (tensile)
strain decreases (increases) $C_{v}$. The $C_{v}$ trend with strain is
controlled by the high energy phonon sub-bands. Dominant contribution of the
low/mid (low/high) energy bands in [100] ([110]) wire and their variation under
strain governs the behavior of $\kappa_{l}$.
