7,322 research outputs found
Chiral symmetry breaking in a uniform external magnetic field II. Symmetry restoration at high temperatures and chemical potentials
Chiral symmetry is dynamically broken in quenched, ladder QED at weak gauge
couplings when an external magnetic field is present. In this paper, we show
that chiral symmetry is restored above a critical chemical potential and the
corresponding phase transition is of first order. In contrast, the chiral
symmetry restoration at high temperatures (and at zero chemical potential) is a
second order phase transition.Comment: Latex; 12 pages; 8 postscript figures include
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Characterization of silicon nanowire by use of full-vectorial finite element method.
We have carried out a rigorous H-field-based full-vectorial modal analysis and used it to characterize, more accurately, the abrupt dielectric discontinuity of a high index contrast optical waveguide. The full-vectorial H and E fields and the Poynting vector profiles are described in detail. It has been shown through this work that the mode profile of a circular silicon nanowire is not circular and also contains a strong axial field component. The single-mode operation, vector field profiles, modal hybridness, modal ellipticity, and group velocity dispersion of this silicon nanowire are also presented
Electron Mass Operator in a Strong Magnetic Field and Dynamical Chiral Symmetry Breaking
The electron mass operator in a strong magnetic field is calculated. The
contribution of higher Landau levels of virtual electrons, along with the
ground Landau level, is shown to be essential in the leading log approximation.
The effect of the electron dynamical mass generation by a magnetic field is
investigated. In a model with N charged fermions, it is shown that some
critical number N_{cr} exists for any value of the electromagnetic coupling
constant alpha, such that the fermion dynamical mass is generated with a
doublet splitting for N < N_{cr}, and the dynamical mass does not arise at all
for N > N_{cr}, thus leaving the chiral symmetry unbroken.Comment: 4 pages, REVTEX4, 3 figure
Interplay between multiple scattering, emission, and absorption of light in the phosphor of a white light-emitting diode
We study light transport in phosphor plates of white light-emitting diodes
(LEDs). We measure the broadband diffuse transmission through phosphor plates
of varying YAG:Ce density. We distinguish the spectral ranges where
absorption, scattering, and re-emission dominate. Using diffusion theory, we
derive the transport and absorption mean free paths from first principles. We
find that both transport and absorption mean free paths are on the order of the
plate thickness. This means that phosphors in commercial LEDs operate well
within an intriguing albedo range around 0.7. We discuss how salient parameters
that can be derived from first principles control the optical properties of a
white LED.Comment: 14 pages, 9 figure
Perturbative Approach to the Quasinormal Modes of Dirty Black Holes
Using a recently developed perturbation theory for uasinormal modes (QNM's),
we evaluate the shifts in the real and imaginary parts of the QNM frequencies
due to a quasi-static perturbation of the black hole spacetime. We show the
perturbed QNM spectrum of a black hole can have interesting features using a
simple model based on the scalar wave equation.Comment: Published in PR
Predicting phase transition pressure in solids: a semiclassical possibility
This is a short review of the physical ideas,algorithm for calculations and
some results of a semiclassical theory of the behaviour of materials under high
pressure,proposed by P.Savic and R.Kasanin.The theory has found applications
from DAC experiments to studies of planetary interior structure.Comment: PDF file,no figure
Small-molecule suppressors of proteoglycan catabolism in degenerative disc cells
INTRODUCTION: Proteoglycans (PGs) occupy the predominant extracellular matrix (ECM) components in cartilages and intervertebral discs (IVDs). Large numbers of compositional glycosaminoglycans (GAGs) render PG highly hydrophilic for providing water retention capacity and swelling pressure to the connective tissues to neutralize the axial mechanical loads [1]. Its loss of content is tightly associated with the tissue degeneration. In the intervertebral disc degeneration (IDD), a reduction of PGs in central gelatinous nucleus pulposus (NP) was characterized as the first event, which consequently leads to a replacement of fibrocartilaginous ...postprin
Z Boson Propagator Correction in Technicolor Theories with ETC Effects Included
We calculate the Z boson propagator correction, as described by the S
parameter, in technicolor theories with extended technicolor interactions
included. Our method is to solve the Bethe-Salpeter equation for the requisite
current-current correlation functions. Our results suggest that the inclusion
of extended technicolor interactions has a relatively small effect on S.Comment: 15pages, 8 figure
Fog Radio Access Networks: Mobility management, interference mitigation and resource optimization
In order to make Internet connections ubiquitous and autonomous in our daily lives, maximizing the
utilization of radio resources and social information is one of the major research topics in future mobile
communication technologies. Fog radio access network (FRAN) is regarded as a promising paradigm
for the fifth generation (5G) of mobile networks. FRAN integrates fog computing with RAN and makes
full use of the edge of networks. FRAN would be different in networking, computing, storage and
control as compared with conventional radio access networks (RAN) and the emerging cloud RAN.
In this article, we provide a description of the FRAN architecture, and discuss how the distinctive
characteristics of FRAN make it possible to efficiently alleviate the burden on the fronthaul, backhaul
and backbone networks, as well as reduce content delivery latencies. We will focus on the mobility management, interference mitigation, and resource optimization in FRAN. Our simulation results show
that the proposed FRAN architecture and the associated mobility and resource management mechanisms
can reduce the signaling cost and increase the net utility for the RAN
Matrix metalloproteinase MMP12 is associated with intervertebral disc degeneration
INTRODUCTION: Intervertebral disc (IVD) degeneration is associated with low back pain. However, the molecular changes during the degeneration process is not entirely clear. The loss of nucleus pulposus (NP) integrity is one of the early events of the degeneration. Chondrogenic markers, such as SOX9 and aggrecan, have been commonly used to assess the degree of IVD degeneration. Recent transcriptomic studies have proposed several other candidates that may mark IVD degeneration. These include cartilage oligomeric matrix protein (COMP), matrix gla protein (MGP)[1], fibulin 1 (FBLN1) [2], cytokeratin 18 (KRT18) [3], cadherin-2 (CDH2) [3], cytokeratin 19 (KRT19) [2], and Runt-related transcription factor 2 (RUNX2) [4]. Studies also demonstrated that degenerated NP attains a fibrocartilaginous phenotype [5,6] with increased ...postprin
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