2,002,060 research outputs found
Black Holes in (Quartic) Quasitopological Gravity
We construct quartic quasitopological gravity, a theory of gravity containing
terms quartic in the curvature that yields second order differential equations
in the spherically symmetric case. Up to a term proportional to the quartic
term in Lovelock gravity we find a unique solution for this quartic case, valid
in any dimensionality larger than 4 except 8. This case is the highest degree
of curvature coupling for which explicit black hole solutions can be
constructed, and we obtain and analyze the various black hole solutions that
emerge from the field equations in dimensions. We discuss the
thermodynamics of these black holes and compute their entropy as a function of
the horizon radius. We then make some general remarks about -th order
quasitopological gravity, and point out that the basic structure of the
solutions will be the same in any dimensionality for general apart from
particular cases.Comment: LaTex, 9 figures, 27 pages. A new section on holographic
hydrodynamics is added. Introduction and concluding remarks have been revise
Pair-tunneling resonance in the single-electron transport regime
We predict a new electron pair-tunneling (PT) resonance in non-linear
transport through quantum dots with positive charging energies exceeding the
broadening due to thermal and quantum fluctuations. The PT resonance shows up
in the single-electron transport (SET) regime as a peak in the derivative of
the non-linear conductance when the electrochemical potential of one electrode
matches the average of two subsequent charge addition energies. For a single
level quantum dot (Anderson model) we find the analytic peak shape and the
dependence on temperature, magnetic field and junction asymmetry and compare
with the inelastic cotunneling peak which is of the same order of magnitude. In
experimental transport data the PT resonance may be mistaken for a weak SET
resonance judging only by the voltage dependence of its position. Our results
provide essential clues to avoid such erroneous interpretation of transport
spectroscopy data.Comment: 5 pages, 2 figures, published versio
Durability testing at one atmosphere of advanced catalysts and catalyst supports for automotive gas turbine engine combustors, part 1
The durability of catalysts and catalyst supports in a combustion environment was experimentally demonstrated. A test of 1000 hours duration was completed with two catalysts, using diesel fuel and operating at catalytically supported thermal combustion conditions. The performance of the catalysts was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. The test catalysts proved to be capable of low emissions operation after 1000 hours diesel aging, with no apparent physical degradation of the catalyst support
Tiling models for metadislocations in AlPdMn approximants
The AlPdMn quasicrystal approximants xi, xi', and xi'_n of the 1.6 nm
decagonal phase and R, T, and T_n of the 1.2 nm decagonal phase can be viewed
as arrangements of cluster columns on two-dimensional tilings. We substitute
the tiles by Penrose rhombs and show, that alternative tilings can be
constructed by a simple cut and projection formalism in three dimensional
hyperspace. It follows that in the approximants there is a phasonic degree of
freedom, whose excitation results in the reshuffling of the clusters. We apply
the tiling model for metadislocations, which are special textures of partial
dislocations.Comment: 7 pages, 2 figures, Proceedings of International Conference on
Quasicrystals
Skyrme and Wigner crystals in graphene
At low-energy, the band structure of graphene can be approximated by two
degenerate valleys about which the electronic spectra of the
valence and conduction bands have linear dispersion relations. An electronic
state in this band spectrum is a linear superposition of states from the
and sublattices of the honeycomb lattice of graphene. In a quantizing
magnetic field, the band spectrum is split into Landau levels with level N=0
having zero weight on the sublattice for the valley.
Treating the valley index as a pseudospin and assuming the real spins to be
fully polarized, we compute the energy of Wigner and Skyrme crystals in the
Hartree-Fock approximation. We show that Skyrme crystals have lower energy than
Wigner crystals \textit{i.e.} crystals with no pseudospin texture in some range
of filling factor around integer fillings. The collective mode spectrum
of the valley-skyrmion crystal has three linearly-dispersing Goldstone modes in
addition to the usual phonon mode while a Wigner crystal has only one extra
Goldstone mode with a quadratic dispersion. We comment on how these modes
should be affected by disorder and how, in principle, a microwave absorption
experiment could distinguish between Wigner and Skyrme crystals.Comment: 14 pages with 11 figure
Literature Review of The Store Windows Display Influences on Consumers Attractiveness Through the Layout Design
Windows display is one of the important aspect in retail design in order to increase consumer product awareness. The store windows design had been varied especially with the creative visual merchandiser in managing a visual approach of store windows display. Flat type store windows display often used in Bandung Retail, and has characteristic of its own retail brand image to improve attractiveness. Layout design of a store windows display has an important role for the influence of consumer behavior especially in shopping attitudes. This research identify the effects of WAKAI and MANGO store windows display at Trans Studio Mall on consumer attractiveness through the implementation of layout design principles
Keywords Store Windows, Retail, Attractiveness, Layout design
Interplay between superconductivity and itinerant magnetism in underdoped BaKFeAs ( 0.2) probed by the response to controlled point-like disorder
The response of superconductors to controlled introduction of point-like
disorder is an important tool to probe their microscopic electronic collective
behavior. In the case of iron-based superconductors (IBS), magnetic
fluctuations presumably play an important role in inducing high temperature
superconductivity. In some cases, these two seemingly incompatible orders
coexist microscopically. Therefore, understanding how this unique coexistence
state is affected by disorder can provide important information about the
microscopic mechanisms involved. In one of the most studied pnictide family,
hole-doped BaKFeAs (BaK122), this coexistence occurs over a
wide range of doping levels, 0.16~~0.25. We used
relativistic 2.5 MeV electrons to induce vacancy-interstitial (Frenkel) pairs
that act as efficient point-like scattering centers. Upon increasing dose of
irradiation, the superconducting transition temperature decreases
dramatically. In the absence of nodes in the order parameter this provides a
strong support for a sign-changing pairing. Simultaneously, in the
normal state, there is a strong violation of the Matthiessen's rule and a
decrease (surprisingly, at the same rate as ) of the magnetic transition
temperature , which indicates the itinerant nature of the long-range
magnetic order. Comparison of the hole-doped BaK122 with electron-doped
Ba(FeCo)As (FeCo122) with similar 110~K,
0.02, reveals significant differences in the normal states, with no
apparent Matthiessen's rule violation above on the electron-doped
side. We interpret these results in terms of the distinct impact of impurity
scattering on the competing itinerant antiferromagnetic and
superconducting orders
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