  Universal logarithmic terms in the entanglement entropy appear at quantum
critical points (QCPs) in one dimension (1D) and have been predicted in 2D at
QCPs described by 2D conformal field theories. The entanglement entropy in a
strip geometry at such QCPs can be obtained via the "Shannon entropy" of a 1D
spin chain with open boundary conditions. The Shannon entropy of the XXZ chain
is found to have a logarithmic term that implies, for the QCP of the
square-lattice quantum dimer model, a logarithm with universal coefficient $\pm
0.25$. However, the logarithm in the Shannon entropy of the transverse-field
Ising model, which corresponds to entanglement in the 2D Ising conformal QCP,
is found to have a singular dependence on replica or R\'enyi index resulting
from flows to different boundary conditions at the entanglement cut.
