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Age-dependent Dynamics of Locomotion in Caenorhabditis elegans: A Lyapunov Exponent Analysis

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Ranko Richert¹

¹Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA.

Physical Review Letters

|April 7, 2010

Summary

This summary is machine-generated.

Physical aging in glasses is heterogeneous, not homogeneous. However, fast relaxation modes age homogeneously, explaining apparent consistency with simple models at high frequencies.

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Area of Science:

Materials Science
Condensed Matter Physics
Physical Chemistry

Background:

Physical aging in glass-forming materials is typically described by heterogeneous dynamics, characterized by a dispersion of relaxation rates.
Homogeneous models, based on a single
inner clock
contradict this observed heterogeneity.
The apparent consistency of aging with homogeneous models suggests a need to reconcile these viewpoints.

Purpose of the Study:

To investigate the dynamics of physical aging in glass-forming materials.
To determine whether aging follows homogeneous or heterogeneous models.
To explain the observed consistency between experimental data and homogeneous aging models.

Main Methods:

Analysis of relaxation time dispersion in glass-forming materials.
Investigation of the relationship between fast relaxation modes and macroscopic properties.
Examination of aging behavior across different frequencies, particularly in the excess wing region.

Main Results:

Physical aging in glasses is fundamentally governed by heterogeneous dynamics.
Very fast relaxation modes exhibit homogeneous aging behavior, slaved to macroscopic softening.
A transition to homogeneous aging is observed at higher frequencies, within the excess wing.

Conclusions:

The apparent homogeneous nature of glass aging arises from the dominance of fast modes at high frequencies.
This study reconciles heterogeneous dynamics with observations consistent with homogeneous models.
The findings explain time-aging-time superposition in high-frequency observations of glass aging.