7,409 research outputs found
Bulk matter fields on two-field thick branes
In this paper we obtain a new solution of a brane made up of a scalar field
coupled to a dilaton. There is a unique parameter in the solution, which
decides the distribution of the energy density and will effect the localization
of bulk matter fields. For free vector fields, we find that the zero mode can
be localized on the brane. And for vector fields coupled with the dilaton via
, the condition for localizing the zero mode is
with with , which
includes the case . While the zero mode for free Kalb-Ramond fields can
not be localized on the brane, if only we introduce a coupling between the
Kalb-Ramond fields and the dilaton via .
When the coupling constant satisfies with or
with , the zero mode for the KR fields can
be localized on the brane. For spin half fermion fields, we consider the
coupling between the fermions
and the background scalars with positive Yukawa coupling . The effective
potentials for both chiral fermions have three types of shapes decided by the
relation between the dilaton-fermion coupling constant and the
parameter . For , the zero mode of left-chiral
fermion can be localized on the brane. While for with
or with , the zero mode for
left-chiral fermion also can be localized.Comment: 22 pages, 8 figures, improved version, accepted by Physical Review
First Principles Study of Adsorption of on Al Surface with Hybrid Functionals
Adsorption of molecule on Al surface has been a long standing puzzle
for the first principles calculation. We have studied the adsorption of
molecule on the Al(111) surface using hybrid functionals. In contrast to the
previous LDA/GGA, the present calculations with hybrid functionals successfully
predict that molecule can be absorbed on the Al(111) surface with a
barrier around 0.20.4 eV, which is in good agreement with
experiments. Our calculations predict that the LUMO of molecule is
higher than the Fermi level of the Al(111) surface, which is responsible for
the barrier of the adsorption.Comment: 14 pages, 5 figure
Domain Wall Brane in Eddington Inspired Born-Infeld Gravity
Recently, inspired by Eddington's theory, an alternative gravity called
Eddington-inspired Born-Infeld gravity was proposed by Baados
and Ferreira. It is equivalent to Einstein's general relativity in vacuum, but
deviates from it when matter is included. Interestingly, it seems that the
cosmological singularities are prevented in this theory. Based on the new
theory, we investigate a thick brane model with a scalar field presenting in
the five-dimensional background. A domain wall solution is obtained, and
further, we find that at low energy the four-dimensional Einstein gravity is
recovered on the brane. Moreover, the stability of gravitational perturbations
is ensured in this model.Comment: 16 pages, 2 figures, improved versio
Very large magnetoresistance in FeTaS single crystals
Magnetic moments intercalated into layered transition metal dichalcogenides
are an excellent system for investigating the rich physics associated with
magnetic ordering in a strongly anisotropic, strong spin-orbit coupling
environment. We examine electronic transport and magnetization in
FeTaS, a highly anisotropic ferromagnet with a Curie temperature
K. We find anomalous Hall data confirming a
dominance of spin-orbit coupling in the magnetotransport properties of this
material, and a remarkably large field-perpendicular-to-plane MR exceeding 60%
at 2 K, much larger than the typical MR for bulk metals, and comparable to
state-of-the-art GMR in thin film heterostructures, and smaller only than CMR
in Mn perovskites or high mobility semiconductors. Even within the
FeTaS series, for the current = 0.28 single crystals the MR is
nearly higher than that found previously in the commensurate
compound FeTaS. After considering alternatives, we argue that
the large MR arises from spin disorder scattering in the strong spin-orbit
coupling environment, and suggest that this can be a design principle for
materials with large MR.Comment: 8 pages, 8 figures, accepted in PR
Deterministic quantum teleportation between distant atomic objects
Quantum teleportation is a key ingredient of quantum networks and a building
block for quantum computation. Teleportation between distant material objects
using light as the quantum information carrier has been a particularly exciting
goal. Here we demonstrate a new element of the quantum teleportation landscape,
the deterministic continuous variable (cv) teleportation between distant
material objects. The objects are macroscopic atomic ensembles at room
temperature. Entanglement required for teleportation is distributed by light
propagating from one ensemble to the other. Quantum states encoded in a
collective spin state of one ensemble are teleported onto another ensemble
using this entanglement and homodyne measurements on light. By implementing
process tomography, we demonstrate that the experimental fidelity of the
quantum teleportation is higher than that achievable by any classical process.
Furthermore, we demonstrate the benefits of deterministic teleportation by
teleporting a dynamically changing sequence of spin states from one distant
object onto another
Localization of Bulk Matters on a Thick Anti-de Sitter Brane
In this paper, we investigate the localization and the mass spectra of
gravity and various bulk matter fields on a thick anti-de Sitter (AdS) brane,
by presenting the mass-independent potentials of the Kaluza-Klein (KK) modes in
the corresponding Schr\"{o}dinger equations. For gravity, the potential of the
KK modes tends to infinity at the boundaries of the extra dimension, which
leads to an infinite number of the bound KK modes. Although the gravity zero
mode cannot be localized on the AdS brane, the massive modes are trapped on the
brane. The scalar perturbations of the thick AdS brane have been analyzed, and
the brane is stable under the scalar perturbations. For spin-0 scalar fields
and spin-1 vector fields, the potentials of the KK modes also tend to infinity
at the boundaries of the extra dimension, and the characteristic of the
localization is the same as the case of gravity. For spin-1/2 fermions, by
introducing the usual Yukawa coupling with the
positive coupling constant , the four-dimensional massless left-chiral
fermion and massive Dirac fermions are obtained on the AdS thick brane.Comment: 23 pages, 9 figure
Approximating the monomer-dimer constants through matrix permanent
The monomer-dimer model is fundamental in statistical mechanics. However, it
is #P-complete in computation, even for two dimensional problems. A
formulation in matrix permanent for the partition function of the monomer-dimer
model is proposed in this paper, by transforming the number of all matchings of
a bipartite graph into the number of perfect matchings of an extended bipartite
graph, which can be given by a matrix permanent. Sequential importance sampling
algorithm is applied to compute the permanents. For two-dimensional lattice
with periodic condition, we obtain , where the exact value is
. For three-dimensional lattice with periodic condition,
our numerical result is , {which agrees with the best known
bound .}Comment: 6 pages, 2 figure
Controlling complex networks: How much energy is needed?
The outstanding problem of controlling complex networks is relevant to many
areas of science and engineering, and has the potential to generate
technological breakthroughs as well. We address the physically important issue
of the energy required for achieving control by deriving and validating scaling
laws for the lower and upper energy bounds. These bounds represent a reasonable
estimate of the energy cost associated with control, and provide a step forward
from the current research on controllability toward ultimate control of complex
networked dynamical systems.Comment: 4 pages paper + 5 pages supplement. accepted for publication in
Physical Review Letters;
http://link.aps.org/doi/10.1103/PhysRevLett.108.21870
Understanding Lung Carcinogenesis from a Morphostatic Perspective:Prevention and Therapeutic Potential of Phytochemicals for Targeting Cancer Stem Cells
Lung cancer is still one of the deadliest cancers, with over two million incidences annually. Prevention is regarded as the most efficient way to reduce both the incidence and death figures. Nevertheless, treatment should still be improved, particularly in addressing therapeutic resistance due to cancer stem cells—the assumed drivers of tumor initiation and progression. Phytochemicals in plant-based diets are thought to contribute substantially to lung cancer prevention and may be efficacious for targeting lung cancer stem cells. In this review, we collect recent literature on lung homeostasis, carcinogenesis, and phytochemicals studied in lung cancers. We provide a comprehensive overview of how normal lung tissue operates and relate it with lung carcinogenesis to redefine better targets for lung cancer stem cells. Nine well-studied phytochemical compounds, namely curcumin, resveratrol, quercetin, epigallocatechin-3-gallate, luteolin, sulforaphane, berberine, genistein, and capsaicin, are discussed in terms of their chemopreventive and anticancer mechanisms in lung cancer and potential use in the clinic. How the use of phytochemicals can be improved by structural manipulations, targeted delivery, concentration adjustments, and combinatorial treatments is also highlighted. We propose that lung carcinomas should be treated differently based on their respective cellular origins. Targeting quiescence-inducing, inflammation-dampening, or reactive oxygen species-balancing pathways appears particularly interesting
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