Biomedical subjects

Vitaly A Shneidman

Publications and source records attributed to Vitaly A Shneidman.

5 recordsLinked to original sources

PubMed2006

Collapse of transient nucleation fluxes in a cold Ising ferromagnet.

We report the time-dependent nucleation fluxes and associated nucleation rates in a metastable Ising ferromagnet on square lattice with Metropolis (Glauber-type) dynamics. It is discovered that, with lowering of the temperature, fluxes collapse into several representative transient curves corresponding to magic cluster sizes. Those can be associated with physical droplets, i.e., long-lived configurations which provide a link with the classical Becker-Döring picture.

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PubMed2005

Nucleation rates for high supersaturations.

A new asymptotic expression for the stationary nucleation flux is obtained. The result provides a nontrivial generalization of the classical expression attributed to Zeldovich, and has a much broader domain of applicability. For extremely high supersaturations when the critical cluster number does not exceed a few units, the preexponential of the nucleation rate exhibits an oscillatory behavior. The latter effect increases for systems with high interfacial tension.

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PubMed2004

On the critical cluster in the two-dimensional Ising model: computer-assisted exact results.

For a nearest-neighbor Ising model on a square lattice all cluster configurations with 17 or fewer spins are identified. In neglect of cluster-cluster interactions, critical sizes and barriers to nucleation are obtained as functions of temperature and magnetic field for two alternative definitions of a "critical cluster."

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PubMed2003

Nucleation preexponential in dynamic Ising models at moderately strong fields.

A dynamic Ising model on a two-dimensional square lattice with nearest neighbor interactions is considered in the metastable region at low temperatures. A large number of low-energy cluster configurations is identified, and for those configurations a system of kinetic equations is written. Solution is obtained using symbolic computational approaches. This allows one to identify the full expression for the nucleation rate, including the preexponential. The treatment generalizes the earlier study of a different, lattice-gas spin-flip dynamics [V. A. Shneidman and G. M. Nita, Phys. Rev. Lett. 89, 025701 (2002)], for the cases of Glauber and Metropolis dynamics and for a broader region of fields. In addition, connection with the lowest-energy nucleation paths (which can be studied analytically, without computer assistance) is examined.

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PubMed2002

Modulation of the nucleation rate preexponential in a low-temperature Ising system.

A metastable lattice gas with nearest-neighbor interactions and continuous-time dynamics is studied using a generalized Becker-Döring approach in the multidimensional space of cluster configurations. The preexponential of the metastable-state lifetime (inverse of nucleation rate) is found to exhibit distinct peaks at integer values of the inverse supersaturation. Peaks are unobservable (infinitely narrow) in the strict limit T-->0, but become detectable and eventually dominate at higher temperatures.

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