\begin{center}
\includegraphics[width=0.9\textwidth]{figures/salt/2013-03-04-CaCl2}
\caption{I27 runs from 2013-03-04 with (red) and without (blue) an
- extra $0.5\U{m}$ \Ca. Clockwise from the upper left, we have
+ extra $0.5\U{M}$ \Ca. Clockwise from the upper left, we have
the distance (in nm) between peaks, the unfolding force (in pN),
and example force curve, and a scatter plot of unfolding force
(in pN) versus the distance between peaks. All of the pulls