Figure 3.

CDF of squared step size at increased time lag. For both groups, only displacements used to calculate $\text{MSD}\left(t_{lag}=1.254s\right)$ are included. Bin size is $\delta r^2=0.04\mu m^2$. CDF (solid circles) is fit to Eq. 3 (solid curves). Also shown for comparison is a fit to a simple exponential $P\left(\Delta r^2,t_{lag}\right)=1-\text{exp}\left(-\Delta r^2/r_o^2\right)$ (dashed curves). (A) A fit to the untreated group using Eq. 3 gives $r_o^2-\Delta =0.250\mu m^2$ and $\varepsilon =0.575$. (B) A fit to the MβCD-treated group using Eq. 3 gives $r_o^2-\Delta =0.288\mu m^2$ and $\varepsilon =0.685$. Because the diffusive portion of the MβCD group fits perfectly with free diffusion, it is appropriate to obtain the diffusion constant. We obtain $D=0.0615\mu m^2/s$. The variance of the fit to the MβCD-treated group ($S^2=2.67\times {10}^{-3}$) is more than a factor of 10 smaller than the variance of the fit to the untreated group ($S^2=2.76\times {10}^{-2}$).