230,310 research outputs found
On the hydrostatic approximation of the Navier-Stokes equations in a thin strip
In this paper, we first prove the global well-posedness of a scaled
anisotropic Navier-Stokes system and the hydrostatic Navier-Stokes system in a
2-D striped domain with small analytic data in the tangential variable. Then we
justify the limit from the anisotropic Navier-Stokes system to the hydrostatic
Navier-Stokes system with analytic data
Electromagnetic energy storage and power dissipation in nanostructures
The processes of storage and dissipation of electromagnetic energy in
nanostructures depend on both the material properties and the geometry. In this
paper, the distributions of local energy density and power dissipation in
nanogratings are investigated using the rigorous coupled-wave analysis. It is
demonstrated that the enhancement of absorption is accompanied by the
enhancement of energy storage both for material at the resonance of its
dielectric function described by the classical Lorentz oscillator and for
nanostructures at the resonance induced by its geometric arrangement. The
appearance of strong local electric field in nanogratings at the
geometry-induced resonance is directly related to the maximum electric energy
storage. Analysis of the local energy storage and dissipation can also help
gain a better understanding of the global energy storage and dissipation in
nanostructures for photovoltaic and heat transfer applications
Resonant Tunneling through S- and U-shaped Graphene Nanoribbons
We theoretically investigate resonant tunneling through S- and U-shaped
nanostructured graphene nanoribbons. A rich structure of resonant tunneling
peaks are found eminating from different quasi-bound states in the middle
region. The tunneling current can be turned on and off by varying the Fermi
energy. Tunability of resonant tunneling is realized by changing the width of
the left and/or right leads and without the use of any external gates.Comment: 6 pages, 7 figure
Unitarity and Complete Reducibility of Certain Modules over Quantized Affine Lie Algebras
Let denote the quantized affine Lie algebra and
the quantized {\em nontwisted} affine Lie algebra. Let
be the category defined in section 3. We show that when
the deformation parameter is not a root of unit all integrable
representations of in the category are
completely reducible and that every integrable irreducible highest weight
module over corresponding to is equivalent to a
unitary module.Comment: 17 pages (minor errors corrected
Tunnelling Effect and Hawking Radiation from a Vaidya Black Hole
In this paper, we extend Parikh' work to the non-stationary black hole. As an
example of the non-stationary black hole, we study the tunnelling effect and
Hawking radiation from a Vaidya black hole whose Bondi mass is identical to its
mass parameter. We view Hawking radiation as a tunnelling process across the
event horizon and calculate the tunnelling probability. We find that the result
is different from Parikh's work because is the function of
Bondi mass m(v)
Updated Estimate of the Muon Magnetic Moment Using Revised Results from e+e- Annihilation
A new evaluation of the hadronic vacuum polarization contribution to the muon
magnetic moment is presented. We take into account the reanalysis of the
low-energy e+e- annihilation cross section into hadrons by the CMD-2
Collaboration. The agreement between e+e- and tau spectral functions in the pi
pi channel is found to be much improved. Nevertheless, significant
discrepancies remain in the center-of-mass energy range between 0.85 and 1.0
GeV, so that we refrain from averaging the two data sets. The values found for
the lowest-order hadronic vacuum polarization contributions are a_mu[had,LO] =
(696.3 +- 6.2[exp] +- 3.6[rad])e-10 (e+e- -based) and a_mu[had,LO] = (711.0 +-
5.0[exp] +- 0.8[rad] +- 2.8[SU2])e-10 (tau-based), where the errors have been
separated according to their sources: experimental, missing radiative
corrections in e+e- data, and isospin breaking. The corresponding Standard
Model predictions for the muon magnetic anomaly read a_mu = (11,659,180.9 +-
7.2[had] +- 3.5[LBL] +- 0.4[QED+EW])e-10 (e+e- -based) and a_mu = (11,659,195.6
+- 5.8[had] +- 3.5[LBL] +- 0.4[QED+EW])e-10 (tau-based), where the errors
account for the hadronic, light-by-light (LBL) scattering and electroweak
contributions. The deviations from the measurement at BNL are found to be (22.1
+- 7.2 +- 3.5 +- 8.0)e-10 (1.9 sigma) and (7.4 +- 5.8 +- 3.5 +- 8.0)e-10 (0.7
sigma) for the e+e- and tau-based estimates, respectively, where the second
error is from the LBL contribution and the third one from the BNL measurement.Comment: 14 pages, 7 figures (to be submitted to Phys Lett B
Evolving small-world networks with geographical attachment preference
We introduce a minimal extended evolving model for small-world networks which
is controlled by a parameter. In this model the network growth is determined by
the attachment of new nodes to already existing nodes that are geographically
close. We analyze several topological properties for our model both
analytically and by numerical simulations. The resulting network shows some
important characteristics of real-life networks such as the small-world effect
and a high clustering.Comment: 11 pages, 4 figure
Dimerization in a half-filled one-dimensional extended Hubbard model
We use a density matrix renormalization group method to study quantitatively
the phase diagram of a one-dimensional extended Hubbard model at half-filling
by investigating the correlation functions and structure factors. We confirm
the existence of a novel narrow region with long-rang bond-order-wave order
which is highly controversial recently between the charge-density-wave phase
and Mott insulator phase. We determined accurately the position of the
tricritical point , which is quite different
from previous studies
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