SimFil is a program designed to demonstrate how a lumped-parameter model of a flexible cytoskeletal filament can capture several key biophysical features of real filaments: deflection under static load, relaxation time-constant, and thermal writhing.

This code was extracted and simplified from research oriented simulations of complex cell biology behaviors in which very many flexible filaments polymerize and interact through forces with each other and with other objects.

This tutorial will briefly discuss the biophysics of each tuning criteria and show you how to determine good tuning coefficients for any set of filament, environmental, and simulation properties. In addition, pre-tuned parameter sets are provided for actin filaments and microtubules under typical cellular conditions.

To start a simulation, do the following two things..

• Choose a TuningTask or StabilityDemo from those menus
• Start the simulation with Program -> Run

Explore the menus... you can Pause, Restart, Write Jpegs, turn Brownian motion on/off, etc

On Windows, or any machine with a 3-button mouse, use the center and right-click buttons to zoom and translate. On Macs, try using the option and open-apple key in conjunction with the mouse button to zoom and translate. If the view gets confusing, use View -> Reset View from the top menu.