Biomedical subjects

A V Zolotaryuk

Publications and source records attributed to A V Zolotaryuk.

7 recordsLinked to original sources

PubMed2004

Discrete kink dynamics in hydrogen-bonded chains: the two-component model.

We study discrete topological solitary waves (kinks and antikinks) in two nonlinear diatomic chain models that describe the collective dynamics of proton transfers in one-dimensional hydrogen-bonded networks. The essential ingredients of the models are (i) a realistic (anharmonic) ion-proton interaction in the hydrogen bond, (ii) a harmonic coupling between the protons in adjacent hydrogen bonds, and (iii) a harmonic coupling between the nearest-neighbor heavy ions (an isolated diatomic chain with the lowest acoustic band) or instead a harmonic on-site potential for the heavy ions (a diatomic chain subject to a substrate with two optical bands), both providing a bistability of the hydrogen-bonded proton. Exact two-component (kink and antikink) discrete solutions for these models are found numerically. We compare the soliton solutions and their properties in both the one- (when the heavy ions are fixed) and two-component models. The effect of stability switchings, discovered previously for a class of one-component kink-bearing models, is shown to exist in these two-component models as well. However, the presence of the second component, i.e., the softness of the heavy-ion sublattice, brings principal differences, like a significant difference in the stability switchings behavior for the kinks and the antikinks. Water-filled carbon nanotubes are briefly discussed as possible realistic systems, where topological discrete (anti)kink states might exist.

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PubMed2003

Existence and stability of discrete gap breathers in a diatomic beta Fermi-Pasta-Ulam chain.

We study the existence and stability of discrete breathers in a chain consisting of alternating light and heavy particles, with nearest-neighbor coupling containing quartic soft or hard anharmonicity. This study is focused on breathers with frequency in the gap that separates the acoustic and optical bands of the phonon spectrum. Simple analytical and physical results obtained through explicit solutions of algebraic equations demonstrate the possibility of the existence of gap breathers with both types of symmetry, i.e., symmetric and antisymmetric. The specific pattern depends on the type of anharmonicity present, i.e., soft or hard, and whether the center of the breather is on a light or a heavy particle. These analytical results are verified systematically through the use of a numerically exact procedure from the anticontinuous limit.

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PubMed2002

Discrete kink dynamics in hydrogen-bonded chains: the one-component model.

We study topological solitary waves (kinks and antikinks) in a nonlinear one-dimensional Klein-Gordon chain with the on-site potential of a double-Morse type. This chain is used to describe the collective proton dynamics in quasi-one-dimensional networks of hydrogen bonds, where the on-site potential plays the role of the proton potential in the hydrogen bond. The system supports a rich variety of stationary kink solutions with different symmetry properties. We study the stability and bifurcation structure of all these stationary kink states. An exactly solvable model with a piecewise "parabola-constant" approximation of the double-Morse potential is suggested and studied analytically. The dependence of the Peierls-Nabarro potential on the system parameters is studied. Discrete traveling-wave solutions of a narrow permanent profile are shown to exist, depending on the anharmonicity of the Morse potential and the cooperativity of the hydrogen bond (the coupling constant of the interaction between nearest-neighbor protons).

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PubMed2002

Heat conduction in one-dimensional systems with hard-point interparticle interactions.

Results of extensive and accurate numerical studies on heat transfer in a system of particles with unequal masses, interacting through hard-point potentials with two types of symmetry, are reported. The particles are confined in a one-dimensional box with fixed ends coupled to heat reservoirs at different temperatures. The study aims to throw light upon recent controversial results on thermal conductivity in one-dimensional systems. When the particles interact through elastic hard-point collisions (a standard asymmetric case), the system is shown to have always infinite (anomalous) thermal conductivity as follows from the Prosen-Campbell theorem.

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PubMed2001

Ratchet due to broken friction symmetry.

A ratchet mechanism that occurs due to asymmetric dependence of the friction of a moving system on its velocity or a driving force is reported. For this kind of ratchet, instead of a particle moving in a periodic potential, the dynamics of which have broken space-time symmetry, the system must be provided with some internal structure realizing such a velocity- or force-friction dependence. For demonstration of a ratchet mechanism of this type, an experimental setup (gadget) that converts longitudinal oscillating or fluctuating motion into a unidirectional rotation has been built and experiments with it have been carried out. In this device, an asymmetry of friction dependence on an applied force appears, resulting in rectification of rotary motion. In experiments, our setup is observed to rotate only in one direction, which is in accordance with given theoretical arguments. Despite the setup being three dimensional, the ratchet rotary motion is proved to be described by one dynamical equation. This kind of motion is a result of the interplay of friction and inertia. We also consider a case with viscous friction, which is irrelevant to this gadget, but it can be a possible mechanism of rotary unidirectional motion of some swimming organisms in a liquid.

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PubMed1999

Dependence of thermal conductivity on discrete breathers in lattices.

We study the properties of heat conduction in chains of coupled particles subjected to different anharmonic on-site potentials. Particular emphasis is placed on the role of breathers in saturation of the thermal conductivity for chains with hard anharmonicity. When the chain particles are subject to on-site potentials with soft anharmonicity, we find a characteristic temperature, below which the conductivity decreases but while above which it increases.

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PubMed1999

Soliton-breather reaction pathways.

We use a collective coordinate approach to investigate corpuscular properties of breathers in nonlinear lattice systems. We calculate the breather internal energy and inertial mass and use them to analyze the reaction pathways of breathers with kinks that are preformed in the lattice. We find that there is an effective kink-breather intraction potential that, under some circumstances, is attractive and has a double well shape. Furthermore, we find that in some cases the internal energy of a moving breather can be released during the reaction with the kink and subsequently transformed to kink translational energy. These breather properties seem to be model independent.

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