9,920 research outputs found
Gravitational waves from binary systems in circular orbits: Convergence of a dressed multipole truncation
The gravitational radiation originating from a compact binary system in
circular orbit is usually expressed as an infinite sum over radiative multipole
moments. In a slow-motion approximation, each multipole moment is then
expressed as a post-Newtonian expansion in powers of v/c, the ratio of the
orbital velocity to the speed of light. The bare multipole truncation of the
radiation consists in keeping only the leading-order term in the post-Newtonian
expansion of each moment, but summing over all the multipole moments. In the
case of binary systems with small mass ratios, the bare multipole series was
shown in a previous paper to converge for all values v/c < 2/e, where e is the
base of natural logarithms. In this paper, we extend the analysis to a dressed
multipole truncation of the radiation, in which the leading-order moments are
corrected with terms of relative order (v/c)^2 and (v/c)^3. We find that the
dressed multipole series converges also for all values v/c < 2/e, and that it
coincides (within 1%) with the numerically ``exact'' results for v/c < 0.2.Comment: 9 pages, ReVTeX, 1 postscript figur
Scattering of 42 MeV /6.7-pJ/ alpha particles from even isotopes of cadmium. Supplement 1 - Absolute cross sections
Absolute cross sections for scattering of 42 MeV alpha particles from even isotopes of cadmiu
Elastic and inelastic scattering of 42-MeV alpha particles from even tellurium isotopes
Angular distributions of elastic and inelastic scattering of 42-MeV alpha particles measured for even tellurium isotope
Gamma ray angular correlations following inelastic scattering of 42-MeV alpha particles from magnesium 24
Angular correlation between inelastically scattered alpha particles and gamma rays emitted in subsequent nuclear decay of magnesium 2
Delay Induced Instabilities in Self-Propelling Swarms
We consider a general model of self-propelling particles interacting through
a pairwise attractive force in the presence of noise and communication time
delay. Previous work by Erdmann, et al. [Phys. Rev. E {\bf 71}, 051904 (2205)]
has shown that a large enough noise intensity will cause a translating swarm of
individuals to transition to a rotating swarm with a stationary center of mass.
We show that with the addition of a time delay, the model possesses a
transition that depends on the size of the coupling amplitude. This transition
is independent of the initial swarm state (traveling or rotating) and is
characterized by the alignment of all of the individuals along with a swarm
oscillation. By considering the mean field equations without noise, we show
that the time delay induced transition is associated with a Hopf bifurcation.
The analytical result yields good agreement with numerical computations of the
value of the coupling parameter at the Hopf point.Comment: 4 pages, 5 figures Final revision to appear in PRE Rapid
Communication
Edgeworth Expansion of the Largest Eigenvalue Distribution Function of GUE Revisited
We derive expansions of the resolvent
Rn(x;y;t)=(Qn(x;t)Pn(y;t)-Qn(y;t)Pn(x;t))/(x-y) of the Hermite kernel Kn at the
edge of the spectrum of the finite n Gaussian Unitary Ensemble (GUEn) and the
finite n expansion of Qn(x;t) and Pn(x;t). Using these large n expansions, we
give another proof of the derivation of an Edgeworth type theorem for the
largest eigenvalue distribution function of GUEn. We conclude with a brief
discussion on the derivation of the probability distribution function of the
corresponding largest eigenvalue in the Gaussian Orthogonal Ensemble (GOEn) and
Gaussian Symplectic Ensembles (GSEn)
Formation and stability of self-assembled coherent islands in highly mismatched heteroepitaxy
We study the energetics of island formation in Stranski-Krastanow growth
within a parameter-free approach. It is shown that an optimum island size
exists for a given coverage and island density if changes in the wetting layer
morphology after the 3D transition are properly taken into account. Our
approach reproduces well the experimental island size dependence on coverage,
and indicates that the critical layer thickness depends on growth conditions.
The present study provides a new explanation for the (frequently found) rather
narrow size distribution of self-assembled coherent islands.Comment: 4 pages, 5 figures, In print, Phys. Rev. Lett. Other related
publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm
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