Thermally activated particle motion in biased correlated Gaussian disorder potentials.

Thermally activated particle motion in disorder potentials is controlled by the large-ΔV tail of the distribution of height ΔV of the potential barriers created by the disorder. We employ the optimal fluctuation method to evaluate this tail for correlated quenched Gaussian potentials in one dimension in the presence of a small bias of the potential. We focus on the mean escape time (MET) of overdamped particles averaged over the disorder.

Spontaneous Vibrations and Stochastic Resonance of Short Oligomeric Springs.

There is growing interest in molecular structures that exhibit dynamics similar to bistable mechanical systems. These structures have the potential to be used as two-state operating units for various functional purposes. Particularly intriguing are the bistable systems that display spontaneous vibrations and stochastic resonance.

Spontaneous Synchronization of Two Bistable Pyridine-Furan Nanosprings Connected by an Oligomeric Bridge.

The intensive development of nanodevices acting as two-state systems has motivated the search for nanoscale molecular structures whose long-term conformational dynamics are similar to the dynamics of bistable mechanical systems such as Euler arches and Duffing oscillators. Collective synchrony in bistable dynamics of molecular-sized systems has attracted immense attention as a potential pathway to amplify the output signals of molecular nanodevices. Recently, pyridine-furan oligomers of helical shape that are a few nanometers in size and exhibit bistable dynamics similar to a Duffing oscillator have been identified through molecular dynamics simulations.

Oligomeric "Catastrophe Machines" with Thermally Activated Bistability and Stochastic Resonance.

The desire to create nanometer-scale switching devices has motivated an active search for bistate macromolecular systems allowing for sharp conformational transitions in response to stimuli. Using full-atomic simulations, we found particular oligomers of thermosensitive polymers, themselves only a few nanometers in size, that possessed conformational bistability and reacted to power loads as nonlinear mechanical systems, termed "catastrophe machines". We established the bifurcation and hysteresis effects, spontaneous vibrations, and stochastic resonance for these oligomers.

Anomalous one-dimensional fluctuations of a simple two-dimensional random walk in a large-deviation regime.

The following question is the subject of our work: could a two-dimensional (2D) random path pushed by some constraints to an improbable "large-deviation regime" possess extreme statistics with one-dimensional (1D) Kardar-Parisi-Zhang (KPZ) fluctuations? The answer is positive, though nonuniversal, since the fluctuations depend on the underlying geometry. We consider in detail two examples of 2D systems for which imposed external constraints force the underlying stationary stochastic process to stay in an atypical regime with anomalous statistics. The first example deals with the fluctuations of a stretched 2D random walk above a semicircle or a triangle.