38,589 research outputs found
The stability of parallel-propagating circularly polarized Alfvén waves revisited
The parametric instability of parallel-propagating circularly polarized Alfven waves (pump waves) is revisited. The stability of these waves is determined by the linearized system of magnetohydrodynamic equations with periodic coefficients. The variable substitution that reduces this system of equations to a system with constant coefficients is suggested. The system with constant coefficients is used to derive the dispersion equation that was previously derived by many authors with the use of different approaches. The dependences of general stability properties on the dimensionless amplitude of the pump wave a and the ratio of the sound and Alfven speed b are studied analytically. It is shown that, for any a and b, there are such quantities k(1) and k(2) that a perturbation with the dimensionless wavenumber k is unstable if k(1)(2) 1, k(1) is a monotonically increasing function of a. For any b, k(1) tends to a limiting value approximately equal to 1.18 as a -> infinity
Changes in the Financial System: Implication for Monetary Policy
macroeconomics, monetary policy, financial system
DISSPLA plotting routines for the G-189A EC/LS computer program
Data from a G-189A execution is formatted and plotted. The plotting may be done at the time of execution of the program. DISSPLA plot packages are used. The user has the choice of FR80 or TEKTRONIX output
Semistability vs. nefness for (Higgs) vector bundles
According to Miyaoka, a vector bundle E on a smooth projective curve is
semistable if and only if a certain numerical class in the projectivized bundle
PE is nef. We establish a similar criterion for the semistability of Higgs
bundles: namely, such a bundle is semistable if and only if for every integer s
between 0 and the rank of E, a suitable numerical class in the scheme
parametrizing the rank s locally-free Higgs quotients of E is nef. We also
extend this result to higher-dimensional complex projective varieties by
showing that the nefness of the above mentioned classes is equivalent to the
semistability of the Higgs bundle E together with the vanishing of the
discriminant of E.Comment: Comments: 20 pages, Latex2e, no figures. v2 includes a generalization
to complex projective manifolds of any dimension. To appear in Diff. Geom.
App
- …