Repairing Spiral Springs

ESCRT Filaments as Spiral Springs.

In a recent issue of Cell, Chiaruttini et al. (2015) reveal the mechanical properties of the mysterious spiral filaments formed by the yeast ESCRT-III protein Snf7. The spirals are shown to be springs whose bending drives membrane deformation and perhaps membrane scission.

Relaxation of Loaded ESCRT-III Spiral Springs Drives Membrane Deformation

ESCRT-III is required for lipid membrane remodeling in many cellular processes, from abscission to viral budding and multi-vesicular body biogenesis. However, how ESCRT-III polymerization generates membrane curvature remains debated. Here, we show that Snf7, the main component of ESCRT-III, polymerizes into spirals at the surface of lipid bilayers. When covering the entire membrane surface, the...

[university of Colorado at Colorado Springs,colorado Springs, Colorado]

Spiral length design

On the circular curve, lateral acceleration affects comfort. On the spiral, both lateral acceleration and jerk affect comfort.  The determination of maximum curving speed on the basis of lateral acceleration only is not critical because the lateral acceleration is proportional to the square of speed whereas jerk is proportional to cubic power of speed. The maximum speed on a curve is thus signi...

Koopmans' springs to life.

The meaning of orbital energies (OOEs) in Kohn-Sham (KS) density functional theory (DFT) is subject to a longstanding controversy. In local, semilocal, and hybrid density functionals (DFs) a Koopmans' approach, where OOEs approximate negative ionization potentials (IPs), is unreliable. We discuss a methodology based on the Baer-Neuhauser-Livshits range-separated hybrid DFs for which Koopmans' a...