67,410 research outputs found
Comment on “Does the Hydrated Electron Occupy a Cavity?” [Science 329, 65, (2010)]
Exact quantum mechanical calculations examining a recently implemented pseudopotential show that the results reported by Larsen et al. are based on a model that contains inaccuracies. We illustrate that, in contrast to the model used, the true electron-water interaction is repulsive in the region relevant to the reported extended electron distribution, consistent with the cavity model. The reported simulated properties of the hydrated electron are shown to be very sensitive to this problem
Origin of the roughness exponent in elastic strings at the depinning threshold
Within a recently developed framework of dynamical Monte Carlo algorithms, we
compute the roughness exponent of driven elastic strings at the
depinning threshold in 1+1 dimensions for different functional forms of the
(short-range) elastic energy. A purely harmonic elastic energy leads to an
unphysical value for . We include supplementary terms in the elastic
energy of at least quartic order in the local extension. We then find a
roughness exponent of , which coincides with the one
obtained for different cellular automaton models of directed percolation
depinning. The quartic term translates into a nonlinear piece which changes the
roughness exponent in the corresponding continuum equation of motion. We
discuss the implications of our analysis for higher-dimensional elastic
manifolds in disordered media.Comment: 4 pages, 2 figure
Representation of SO(3) Group by a Maximally Entangled State
A representation of the SO(3) group is mapped into a maximally entangled two
qubit state according to literatures. To show the evolution of the entangled
state, a model is set up on an maximally entangled electron pair, two electrons
of which pass independently through a rotating magnetic field. It is found that
the evolution path of the entangled state in the SO(3) sphere breaks an odd or
even number of times, corresponding to the double connectedness of the SO(3)
group. An odd number of breaks leads to an additional phase to the
entangled state, but an even number of breaks does not. A scheme to trace the
evolution of the entangled state is proposed by means of entangled photon pairs
and Kerr medium, allowing observation of the additional phase.Comment: 4 pages, 3 figure
Directed percolation depinning models: Evolution equations
We present the microscopic equation for the growing interface with quenched
noise for the model first presented by Buldyrev et al. [Phys. Rev. A 45, R8313
(1992)]. The evolution equation for the height, the mean height, and the
roughness are reached in a simple way. The microscopic equation allows us to
express these equations in two contributions: the contact and the local one. We
compare this two contributions with the ones obtained for the Tang and
Leschhorn model [Phys. Rev A 45, R8309 (1992)] by Braunstein et al. [Physica A
266, 308 (1999)]. Even when the microscopic mechanisms are quiet different in
both model, the two contribution are qualitatively similar. An interesting
result is that the diffusion contribution, in the Tang and Leschhorn model, and
the contact one, in the Buldyrev model, leads to an increase of the roughness
near the criticality.Comment: 10 pages and 4 figures. To be published in Phys. Rev.
Observation of polarization domain wall solitons in weakly birefringent cavity fiber lasers
We report on the experimental observation of two types of phase-locked vector
soliton in weakly birefringent cavity erbium-doped fiber lasers. While a
phase-locked dark-dark vector soliton was only observed in fiber lasers of
positive dispersion, a phase-locked dark-bright vector soliton was obtained in
fiber lasers of either positive or negative dispersion. Numerical simulations
confirmed the experimental observations, and further showed that the observed
vector solitons are the two types of phase-locked polarization domain-wall
solitons theoretically predicted.Comment: 14 pages, 4 Figure
Comment on: Kinetic Roughening in Slow Combustion of Paper
We comment on a recent Letter by Maunuksela et al. [Phys. Rev. Lett. 79, 1515
(1997)].Comment: 1 page, 1 figure, http://polymer.bu.edu/~hmakse/Home.htm
Production mechanisms and single-spin asymmetry for kaons in high energy hadron-hadron collisions
Direct consequences on kaon production of the picture proposed in a recent
Letter and subsequent publications are discussed. Further evidence supporting
the proposed picture is obtained. Comparison with the data for the inclusive
cross sections in unpolarized reactions is made. Quantitative results for the
left-right asymmetry in single-spin processes are presented.Comment: 10 pages, 2 Postscript figure
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