Biomedical subjects

A J Lichtenberg

Publications and source records attributed to A J Lichtenberg.

2 recordsLinked to original sources

PubMed1999

Streaminglike diffusion in the low-dimensional stochastic pump model.

In this paper we analyze a diffusion phenomenon in a few-dimensional Hamiltonian system of coupled mappings in which the principal component of diffusion occurs along resonances. The result is that the diffusion can have power-law dependence in coupling parameter mu and be independent of the stochastic parameter K. For the same range of parameters, the usual analytical Arnold diffusion across resonances is dependent on K and can be much smaller than resonance streaming diffusion. The results are used to qualitatively explain recent results in multidimensional coupled standard maps.

Journal Article↗

PubMed1999

Finite times to equipartition in the thermodynamic limit.

We study the time scale T to equipartition in a 1D lattice of N masses coupled by quartic nonlinear (hard) springs (the Fermi-Pasta-Ulam beta model). We take the initial energy to be either in a single mode gamma or in a package of low-frequency modes centered at gamma and of width deltagamma, with both gamma and deltagamma proportional to N. These initial conditions both give, for finite energy densities E/N, a scaling in the thermodynamic limit (large N), of a finite time to equipartition which is inversely proportional to the central mode frequency times a power of the energy density (E/N). A theory of the scaling with (E/N) is presented and compared to the numerical results in the range 0.03<or=E/N<or=0.8.

Journal Article↗