10,665 research outputs found
Time-Dependent Density-Functional Theory for the Stopping Power of an Interacting Electron Gas for Slow Ions
Based on the time-dependent density-functional theory, we have derived a
rigorous formula for the stopping power of an {\it interacting} electron gas
for ions in the limit of low projectile velocities. If dynamical correlation
between electrons is not taken into account, this formula recovers the
corresponding stopping power of {\it noninteracting} electrons in an effective
Kohn-Sham potential. The correlation effect, specifically the excitonic one in
electron-hole pair excitations, however, is found to considerably enhance the
stopping power for intermediately charged ions, bringing our theory into good
agreement with experiment.Comment: 4 pages, 1 figure, Accepted to Phys. Rev. B (Rapid Communication
Draft Genome Sequence of Magnetovibrio blakemorei Strain MV-1, a Marine Vibrioid Magnetotactic Bacterium.
We report here the genome sequence of Magnetovibrio blakemorei MV-1, a marine vibrioid magnetotactic bacterium with a single polar flagellum. The current assembly consists of 91 contigs with a combined size of 3,638,804 bp (54.3% G+C content). This genome allows for further investigations of the molecular biomineralization mechanisms of magnetosome formation
Chern-Simons Solitons, Chiral Model, and (affine) Toda Model on Noncommutative Space
We consider the Dunne-Jackiw-Pi-Trugenberger model of a U(N) Chern-Simons
gauge theory coupled to a nonrelativistic complex adjoint matter on
noncommutative space. Soliton configurations of this model are related the
solutions of the chiral model on noncommutative plane. A generalized
Uhlenbeck's uniton method for the chiral model on noncommutative space provides
explicit Chern-Simons solitons. Fundamental solitons in the U(1) gauge theory
are shaped as rings of charge `n' and spin `n' where the Chern-Simons level `n'
should be an integer upon quantization. Toda and Liouville models are
generalized to noncommutative plane and the solutions are provided by the
uniton method. We also define affine Toda and sine-Gordon models on
noncommutative plane. Finally the first order moduli space dynamics of
Chern-Simons solitons is shown to be trivial.Comment: latex, JHEP style, 23 pages, no figur
Harmonic Superspaces in Low Dimensions
Harmonic superspaces for spacetimes of dimension are constructed.
Some applications are given.Comment: 16, kcl-th-94-15. Two further references have been added (12 and 13)
and a few typographical errors have been correcte
Transformation Optics for Plasmonics
A new strategy to control the flow of surface plasmon polaritons at metallic
surfaces is presented. It is based on the application of the concept of
Transformation Optics to devise the optical parameters of the dielectric medium
placed on top of the metal surface. We describe the general methodology for the
design of Transformation-Optical devices for surface plasmons and analyze, for
proof-of-principle purposes, three representative examples with different
functionalities: a beam shifter, a cylindrical cloak and a ground-plane cloak.Comment: 15 pages, 3 figure
The Dynamical Cluster Approximation: Non-Local Dynamics of Correlated Electron Systems
We recently introduced the dynamical cluster approximation(DCA), a new
technique that includes short-ranged dynamical correlations in addition to the
local dynamics of the dynamical mean field approximation while preserving
causality. The technique is based on an iterative self-consistency scheme on a
finite size periodic cluster. The dynamical mean field approximation (exact
result) is obtained by taking the cluster to a single site (the thermodynamic
limit). Here, we provide details of our method, explicitly show that it is
causal, systematic, -derivable, and that it becomes conserving as the
cluster size increases. We demonstrate the DCA by applying it to a Quantum
Monte Carlo and Exact Enumeration study of the two-dimensional Falicov-Kimball
model. The resulting spectral functions preserve causality, and the spectra and
the CDW transition temperature converge quickly and systematically to the
thermodynamic limit as the cluster size increases.Comment: 19 pages, 13 postscript figures, revte
Twistor theory of hyper-K{\"a}hler metrics with hidden symmetries
We briefly review the hierarchy for the hyper-K\"ahler equations and define a
notion of symmetry for solutions of this hierarchy. A four-dimensional
hyper-K\"ahler metric admits a hidden symmetry if it embeds into a hierarchy
with a symmetry. It is shown that a hyper-K\"ahler metric admits a hidden
symmetry if it admits a certain Killing spinor. We show that if the hidden
symmetry is tri-holomorphic, then this is equivalent to requiring symmetry
along a higher time and the hidden symmetry determines a `twistor group' action
as introduced by Bielawski \cite{B00}. This leads to a construction for the
solution to the hierarchy in terms of linear equations and variants of the
generalised Legendre transform for the hyper-K\"ahler metric itself given by
Ivanov & Rocek \cite{IR96}. We show that the ALE spaces are examples of
hyper-K\"ahler metrics admitting three tri-holomorphic Killing spinors. These
metrics are in this sense analogous to the 'finite gap' solutions in soliton
theory. Finally we extend the concept of a hierarchy from that of \cite{DM00}
for the four-dimensional hyper-K\"ahler equations to a generalisation of the
conformal anti-self-duality equations and briefly discuss hidden symmetries for
these equations.Comment: Final version. To appear in the August 2003 special issue of JMP on
`Integrability, Topological Solitons, and Beyond
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