Stellar Oscillons

We study the weakly nonlinear evolution of acoustic instability of a plane- parallel polytrope with thermal dissipation in the form of Newton's law of cooling. The most unstable horizontal wavenumbers form a band around zero and this permits the development of a nonlinear pattern theory leading to a complex Ginzburg-Landau equation (CGLE). Numerical solutions for a subcritical, quintic CGLE produce vertically oscillating, localized structures that resemble the oscillons observed in recent experiments of vibrated granular material.Comment: 12 Latex pages using aasms4.sty, 2 postscript figures, submitted to the proceedings of the Florida Workshop in Nonlinear Astrophysics and Physic

Gravitational Screening

Calculations of the stopping power of a medium lead to divergent integrals in gravitational theory as they do in the analogous electromagnetic problem. In the em case, one introduces (normally in an arbitrary manner) the Debye length as a cutoff at large distances to remove the divergence. We show here that in the Newtonian gravitational analogue the distant cutoff problem is solved by including the self-gravity of the medium. Then the Jeans length appears naturally as a cutoff. Despite the different sign of the coupling constant from the case of the electric plasma, the same sort of theory works in both cases and removes the need of introducing ad hoc cutoffs from both of them.Comment: 9 pages, appearing in "A Festschrifft for Engelbert Schucking," ed. Alex Harvey, Springer-Verla

Gradualism and Chinese financial reforms

China ; Banks and banking - China ; Monetary policy - China