Active elastic dimers: self-propulsion and current reversal on a featureless track

Area of Science:

• Physics
• Biophysics
• Statistical Mechanics

Background:

• Self-propelled particles exhibit complex behaviors driven by internal mechanisms and external forces.
• Understanding the fundamental principles of nonequilibrium systems is crucial for explaining biological motility.

Purpose of the Study:

• To introduce a novel Brownian inchworm model for a self-propelled elastic dimer.
• To elucidate the propulsion mechanism driven by nonequilibrium noise and stretch-dependent damping.
• To connect key nonequilibrium features like position-velocity correlations, internal forces, and drift velocity.

Main Methods:

• Development of a theoretical Brownian inchworm model for an elastic dimer.
• Analytical derivation of model properties.
• Comparison of analytical results with numerical simulations.

Main Results:

• The model successfully explains self-propulsion in the absence of external potentials.
• Demonstrated connection between position-velocity correlations, nonzero mean internal force, and drift velocity.
• Observed current reversals, validated by numerical simulations.

Conclusions:

• The Brownian inchworm model provides a unified framework for diverse propulsion mechanisms, including DNA helicases, polar rods, keratocytes, and Myosin VI.
• The model offers insights into the fundamental physics of active matter and biological motors.
• Experimental validation and further testing of the model are proposed.