431 research outputs found
Vector field theories in cosmology
Recently proposed theories based on the cosmic presence of a vectorial field
are compared and contrasted. In particular the so called Einstein aether theory
is discussed in parallel with a recent proposal of a strained space-time theory
(Cosmic Defect theory). We show that the latter fits reasonably well the cosmic
observed data with only one, or at most two, adjustable parameters, whilst
other vector theories use much more. The Newtonian limits are also compared.
Finally we show that the CD theory may be considered as a special case of the
aether theories, corresponding to a more compact and consistent paradigm.Comment: 19 pages, 1 figure, to appear on Phys. Rev.
Penerapan Model Pembelajaran Aktif Inquiring Minds Want to Know Guna Meningkatkan Prestasi Belajar Akuntansi Pad Siswa Kelas X Akuntansi Smk Murni 2 Surakarta Tahun Ajaran 2012/2013
The objective of research was to find out whether or not there is an improvement of Accounting learning achievement through inquiring minds want to know type of active learning model in the X Accounting graders of SMK Murni 2 Surakarta in the school year of 2012/2013. This study employed a Classroom Action Research (CAR). The subject of research was the X Accounting graders of SMK Murni 2 Surakarta consisting of 21 students. The result of research showed the increased percentage of affective, psychomotor, and cognitive ability levels among the students. The mean percentage affective level was 69.29% in cycle I and 78.10% in cycle II, increasing by 8.81%. The mean percentage of psychomotor ability was 70.24% in cycle I and 77.38% in cycle II, increasing by 7.14%. The mean percentage of cognitive ability was 69.42% in cycle I and 77.90% in cycle II, increasing by 8.48%. Considering the research conducted, it could be concluded that the inquiring minds want to know type of active learning model use could improve the accounting learning achievement (either process or product). It was reflected on several indicators of student ability assessment improving in each cycle
Photocatalytic-ready supraparticle lasers
A photocatalytic-ready supraparticle laser consisting of a micron-scale CdS x Se 1-x /ZnS quantum dot assembly and a titania shell is demonstrated. Such multifunctional supraparticles could find use in future defence, environment, energy and medical technologies
Relativistic Hydrodynamics with General Anomalous Charges
We consider the hydrodynamic regime of gauge theories with general triangle
anomalies, where the participating currents may be global or gauged, abelian or
non-abelian. We generalize the argument of arXiv:0906.5044, and construct at
the viscous order the stress-energy tensor, the charge currents and the entropy
current.Comment: 13 pages, Revte
Dispersive fields in de Sitter space and event horizon thermodynamics
When Lorentz invariance is violated at high energy, the laws of black hole
thermodynamics are apparently no longer satisfied. To shed light on this
observation, we study dispersive fields in de Sitter space. We show that the
Bunch-Davies vacuum state restricted to the static patch is no longer thermal,
and that the Tolman law is violated. However we also show that, for free fields
at least, this vacuum is the only stationary stable state, as if it were in
equilibrium. We then present a precise correspondence between dispersive
effects found in de Sitter and in black hole metrics. This indicates that the
consequences of dispersion on thermodynamical laws could also be similar.Comment: 19 pages. Black and White version on Phys.Rev.D serve
Black Hole Thermodynamics and Lorentz Symmetry
Recent developments point to a breakdown in the generalized second law of
thermodynamics for theories with Lorentz symmetry violation. It appears
possible to construct a perpetual motion machine of the second kind in such
theories, using a black hole to catalyze the conversion of heat to work. Here
we describe and extend the arguments leading to that conclusion. We suggest the
inference that local Lorentz symmetry may be an emergent property of the
macroscopic world with origins in a microscopic second law of causal horizon
thermodynamics.Comment: 4 pages; v2: Version to appear in Foundations of Physics. Potential
counterexamples addressed, argument given applying to LV theories where all
speeds (or horizons) coincide, and editing for clarit
The universal viscosity to entropy density ratio from entanglement
We present evidence that the universal Kovtun-Son-Starinets shear viscosity
to entropy density ratio of 1/4\pi can be associated with a Rindler causal
horizon in flat spacetime. Since there is no known holographic (gauge/gravity)
duality for this spacetime, a natural microscopic explanation for this
viscosity is in the peculiar properties of quantum entanglement. In particular,
it is well-known that the Minkowski vacuum state is a thermal state and carries
an area entanglement entropy density in the Rindler spacetime. Based on the
fluctuation-dissipation theorem, we expect a similar notion of viscosity
arising from vacuum fluctuations. Therefore, we propose a holographic Kubo
formula in terms of a two-point function of the stress tensor of matter fields
in the bulk. We calculate this viscosity assuming a minimally coupled scalar
field theory and find that the ratio with respect to the entanglement entropy
density is exactly 1/4\pi in four dimensions. The issues that arise in
extending this result to non-minimally coupled scalar fields, higher spins, and
higher dimensions provide interesting hints about the relationship between
entanglement entropy and black hole entropy.Comment: 30 pages; v2: footnote added, minor editin
Dietary n-3 fatty acids increase spleen size and postendotoxin circulating TNF in mice; role of macrophages, macrophage precursors, and colony-stimulating factor-1
Contains fulltext :
4891.pdf (publisher's version ) (Open Access
The holographic fluid dual to vacuum Einstein gravity
We present an algorithm for systematically reconstructing a solution of the
(d+2)-dimensional vacuum Einstein equations from a (d+1)-dimensional fluid,
extending the non-relativistic hydrodynamic expansion of Bredberg et al in
arXiv:1101.2451 to arbitrary order. The fluid satisfies equations of motion
which are the incompressible Navier-Stokes equations, corrected by specific
higher derivative terms. The uniqueness and regularity of this solution is
established to all orders and explicit results are given for the bulk metric
and the stress tensor of the dual fluid through fifth order in the hydrodynamic
expansion. We establish the validity of a relativistic hydrodynamic description
for the dual fluid, which has the unusual property of having a vanishing
equilibrium energy density. The gravitational results are used to identify
transport coefficients of the dual fluid, which also obeys an interesting and
exact constraint on its stress tensor. We propose novel Lagrangian models which
realise key properties of the holographic fluid.Comment: 31 pages; v2: references added and minor improvements, published
versio
From Petrov-Einstein to Navier-Stokes in Spatially Curved Spacetime
We generalize the framework in arXiv:1104.5502 to the case that an embedding
may have a nonvanishing intrinsic curvature. Directly employing the Brown-York
stress tensor as the fundamental variables, we study the effect of finite
perturbations of the extrinsic curvature while keeping the intrinsic metric
fixed. We show that imposing a Petrov type I condition on the hypersurface
geometry may reduce to the incompressible Navier-Stokes equation for a fluid
moving in spatially curved spacetime in the near-horizon limit.Comment: 17 pages, references added, generalizing the metric form in part 3,
version published in JHE
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