196,519 research outputs found
Lagrange Model for the Chiral Optical Properties of Stereometamaterials
We employ a general Lagrange model to describe the chiral optical properties
of stereometamaterials. We derive the elliptical eigenstates of a twisted
stacked split-ring resonator, taking phase retardation into account. Through
this approach, we obtain a powerful Jones matrix formalism which can be used to
calculate the polarization rotation, ellipticity, and circular dichroism of
transmitted waves through stereometamaterials at any incident polarization. Our
experimental measurements agree well with our model.Comment: 10 pages, 3 figures, Theory and experimen
Holographic Heat Current as Noether Current
We employ the Noether procedure to derive a general formula for the radially
conserved heat current in AdS planar black holes with certain transverse and
traceless perturbations, for a general class of gravity theories. For Einstein
gravity, the general higher-order Lovelock gravities and also a class of
Horndeski gravities, we derive the boundary stress tensor and show that the
resulting boundary heat current matches precisely the bulk Noether current.Comment: Latex, 27 pages, typos corrected, comments added, references adde
Thermodynamics of Einstein-Proca AdS Black Holes
We study static spherically-symmetric solutions of the Einstein-Proca
equations in the presence of a negative cosmological constant. We show that the
theory admits solutions describing both black holes and also solitons in an
asymptotically AdS background. Interesting subtleties can arise in the
computation of the mass of the solutions and also in the derivation of the
first law of thermodynamics. We make use of holographic renormalisation in
order to calculate the mass, even in cases where the solutions have a rather
slow approach to the asymptotic AdS geometry. By using the procedure developed
by Wald, we derive the first law of thermodynamics for the black hole and
soliton solutions. This includes a non-trivial contribution associated with the
Proca "charge." The solutions cannot be found analytically, and so we make use
of numerical integration techniques to demonstrate their existence.Comment: 35 pages, Improved discussion of cases with logarithmic asymptotic
fall off
Generalised Smarr Formula and the Viscosity Bound for Einstein-Maxwell-Dilaton Black Holes
We study the shear viscosity to entropy ratio in the boundary field
theories dual to black hole backgrounds in theories of gravity coupled to a
scalar field, and generalisations including a Maxwell field and non-minimal
scalar couplings. Motivated by the observation in simple examples that the
saturation of the bound is correlated with the existence
of a generalised Smarr relation for the planar black-hole solutions, we
investigate this in detail for the general black-hole solutions in these
theories, focusing especially on the cases where the scalar field plays a
non-trivial role and gives rise to an additional parameter in the space of
solutions. We find that a generalised Smarr relation holds in all cases, and in
fact it can be viewed as the bulk gravity dual of the statement of the
saturation of the viscosity to entropy bound. We obtain the generalised Smarr
relation, whose existence depends upon a scaling symmetry of the planar
black-hole solutions, by two different but related methods, one based on
integrating the first law of thermodynamics, and the other based on the
construction of a conserved Noether charge.Comment: Latex, 36 pages, references added, typos corrected, to appear in PR
The Numerical Solution of Scalar Field for Nariai Case in 5D Ricci-flat SdS Black String Space with Polynomial Approximation
As one exact candidate of the higher dimensional black hole, the 5D
Ricci-flat Schwarzschild-de Sitter black string space presents something
interesting. In this paper, we give a numerical solution to the real scalar
field around the Nariai black hole by the polynomial approximation. Unlike the
previous tangent approximation, this fitting function makes a perfect match in
the leading intermediate region and gives a good description near both the
event and the cosmological horizons. We can read from our results that the wave
is close to a harmonic one with the tortoise coordinate. Furthermore, with the
actual radial coordinate the waves pile up almost equally near the both
horizons.Comment: 8 pages, 4 figure
Magnetically-Charged Black Branes and Viscosity/Entropy Ratios
We consider asymptotically-AdS -dimensional black brane solutions in a
theory of gravity coupled to a set of -form field strengths, in which
the field strengths carry magnetic charges. For appropriately chosen charges,
the metrics are isotropic in the transverse directions. However, in
general the field strength configurations break the full Euclidean symmetry of
the -dimensional transverse space. We then study the linearised equation
for transverse traceless metric perturbations in these backgrounds, and by
employing the Kubo formula we obtain expressions for , the ratio of
shear viscosity to entropy density. We find that the KSS bound on the ratio
is generally violated in these solutions. We also extend the
discussion by including also a dilatonic scalar field in the theory, leading to
solutions that are asymptotically Lifshitz with hyperscaling violation.Comment: References added. 21 page
Urban Regeneration of Industrial Areas: Affordable Housing for Low Income Populations in Cities
The UK-China Sustainable Development Dialogue (SDD) is a partnership between the UK and Chinese Governments to promote collaboration and good practice on sustainable development. It is framed by a 2004 joint Prime Ministerial declaration and was formally established in 2005 by an agreement signed by UK Deputy Prime Minister John Prescott and State Councillor Tang. The SDD was founded on the recognition that, in an interdependent world, international co-operation is needed to ensure that learning is shared and efforts are made collectively towards achieving common goals. This report is the 13th and Final Paper in the SDD (Urban Strand. It draws together the core conclusions from the previous twelve papers and offers recommendations for taking the dialogue forward
A VLSI architecture of JPEG2000 encoder
Copyright @ 2004 IEEEThis paper proposes a VLSI architecture of JPEG2000 encoder, which functionally consists of two parts: discrete wavelet transform (DWT) and embedded block coding with optimized truncation (EBCOT). For DWT, a spatial combinative lifting algorithm (SCLA)-based scheme with both 5/3 reversible and 9/7 irreversible filters is adopted to reduce 50% and 42% multiplication computations, respectively, compared with the conventional lifting-based implementation (LBI). For EBCOT, a dynamic memory control (DMC) strategy of Tier-1 encoding is adopted to reduce 60% scale of the on-chip wavelet coefficient storage and a subband parallel-processing method is employed to speed up the EBCOT context formation (CF) process; an architecture of Tier-2 encoding is presented to reduce the scale of on-chip bitstream buffering from full-tile size down to three-code-block size and considerably eliminate the iterations of the rate-distortion (RD) truncation.This work was supported in part by the China National High Technologies Research Program (863) under Grant 2002AA1Z142
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