Biomedical subjects

Mykhaylo Evstigneev

Publications and source records attributed to Mykhaylo Evstigneev.

4 recordsLinked to original sources

PubMed2005

Probability densities of periodically driven noisy systems: an approximation scheme incorporating linear-response and adiabatic theory.

We consider periodically driven noisy systems in the limit of long times. To deduce their asymptotic time-periodic probability distributions, two approaches are commonly used: adiabatic theory, valid if driving is very slow, and linear-response theory, applicable when driving is weak. We introduce an approximation scheme that combines these two approaches to yield the driven probability distribution even when driving is strong and moderately fast, so that both linear-response and adiabatic approximations break down. The high accuracy of this scheme is demonstrated on a driven overdamped noisy oscillator in a bistable quartic potential.

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PubMed2005

Rate description of the stick-slip motion in friction force microscopy experiments.

During the stick-slip motion of an atomic force microscope tip contacting with a uniformly moving atomically clean surface, the force developed in the cantilever spring performs random sawtoothlike oscillations resulting from the thermally activated transitions of the tip from one surface site to the next. Using escape rate theory, the probability distribution of forces is calculated numerically to deduce the time-average lateral force as a function of pulling velocity. A transcendental equation for the average force is proposed and its approximate solution is obtained. The accuracy of this analytic approximation is demonstrated via comparison with the numerical results. The analogous force-velocity relations existing in the literature are shown to be the limiting cases of low and high cantilever spring constants of our analytic approximation.

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PubMed2004

Nonmonotonic velocity dependence of atomic friction.

We propose a theoretical model for friction force microscopy experiments with special emphasis on the realistic description of dissipation and inertia effects. Its main prediction is a nonmonotonic dependence of the friction force upon the sliding velocity of the atomic force microscope tip relative to an atomically flat surface. The region around the force maximum can be approximately described by a universal scaling law and should be observable under experimentally realistic conditions.

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PubMed2003

Dynamic force spectroscopy: optimized data analysis.

The forced rupture of single chemical bonds in biomolecular compounds (e.g., ligand-receptor systems) as observed in dynamic force spectroscopy experiments is addressed. An optimized method of data analysis is proposed. This method significantly outperforms the current standard one when applied to data from an idealized numerical computer simulation of an experiment with realistic parameter values. In particular, the force-free dissociation rate can be inferred with a considerably smaller statistical uncertainty and without the systematic overestimation of about 30%, which is shown to be inherent in the standard method.

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