Fig. 4.

Model predictions for filament force buildup. (a) Black line: steady-state filament force f_∞, as a function of motor spacing ℓ₀ [Eq. (6)]. For ${\ell }_0\ll {\ell }_0^{\ast }$ and ${\ell }_0\gg {\ell }_0^{\ast }$, $f_{\infty }\propto {\ell }_0^{-1/2}$ and ${\ell }_0^{-9/2}$, respectively. Colored straight lines: buckling force $F_B\propto {\ell }_0^{-2}$. (b) Typical filament force ${(\overline{\langle f^2\rangle })}^{1/2}$ as a function of time [Eq. (6)]. (c) Contractile unit size ℓ_B as a function of ℓ₀ as in Eq. (8) (ℓ_f ≃ 5 μm).