19,235 research outputs found
Self-organized critical behavior: the evolution of frozen spin networks model in quantum gravity
In quantum gravity, we study the evolution of a two-dimensional planar open
frozen spin network, in which the color (i.e. the twice spin of an edge)
labeling edge changes but the underlying graph remains fixed. The mainly
considered evolution rule, the random edge model, is depending on choosing an
edge randomly and changing the color of it by an even integer. Since the change
of color generally violate the gauge invariance conditions imposed on the
system, detailed propagation rule is needed and it can be defined in many ways.
Here, we provided one new propagation rule, in which the involved even integer
is not a constant one as in previous works, but changeable with certain
probability. In random edge model, we do find the evolution of the system under
the propagation rule exhibits power-law behavior, which is suggestive of the
self-organized criticality (SOC), and it is the first time to verify the SOC
behavior in such evolution model for the frozen spin network. Furthermore, the
increase of the average color of the spin network in time can show the nature
of inflation for the universe.Comment: 5 pages, 5 figure
Two-dimensional small-world networks: navigation with local information
Navigation process is studied on a variant of the Watts-Strogatz small world
network model embedded on a square lattice. With probability , each vertex
sends out a long range link, and the probability of the other end of this link
falling on a vertex at lattice distance away decays as .
Vertices on the network have knowledge of only their nearest neighbors. In a
navigation process, messages are forwarded to a designated target. For and , a scaling relation is found between the average actual
path length and , where is the average length of the additional long
range links. Given , dynamic small world effect is observed, and the
behavior of the scaling function at large enough is obtained. At and 3, this kind of scaling breaks down, and different functions of the
average actual path length are obtained. For , the average actual
path length is nearly linear with network size.Comment: Accepted for publication in Phys. Rev.
Gene Transfer of Calcitonin Gene-Related Peptide Inhibits Macrophages and Inflammatory Mediators in Vein Graft Disease
Vein graft disease is a chronic inflammatory disease and limits the late results of coronary revascularization. Calcitonin gene-related peptide (CGRP) inhibits macrophages infiltrated and inflammatory mediators, we hypothesized that transfected CGRP gene inhibits macrophages infiltrated and inflammatory mediators in vein graft disease. Autologous rabbit jugular vein grafts were incubated ex vivo in a solution of mosaic adeno-associated virus vectors containing CGRP gene (AAV2/1.CGRP) 、escherichia coli lac Z gene (AAV2/1.LacZ) or saline and then interposed in the carotid artery. Intima/media ratio were evaluated at postoperative 4 weeks, Macrophages were marked with CD68 antibody by immunocytochemistry. Inflammatory mediators were mensurated with real-time PCR. Neointimal thickening was significantly suppressed in AAV2/1.CGRP group. Macrophages infiltrated and inflammatory mediators monocyte chemoattractant protein-1 (MCP-1)、tumor necrosis factorα(TNF-α)、inducible nitricoxide synthase (iNOS)、matrix metalloproteinase-9 (MMP-9) was significantly suppressed in AAV2/1.CGRP group.Gene transfected AAV2/1.CGRP suppressed neointimal hyperplasia in vein graft disease by suppressed macrophages infiltrated and inflammatory mediators
Generation of Narrow-Band Polarization-Entangled Photon Pairs for Atomic Quantum Memories
We report an experimental realization of a narrow-band polarization-entangled
photon source with a linewidth of 9.6 MHz through cavity-enhanced spontaneous
parametric down-conversion. This linewidth is comparable to the typical
linewidth of atomic ensemble based quantum memories. Single-mode output is
realized by setting a reasonable cavity length difference between different
polarizations, using of temperature controlled etalons and actively stabilizing
the cavity. The entangled property is characterized with quantum state
tomography, giving a fidelity of 94% between our state and a maximally
entangled state. The coherence length is directly measured to be 32 m through
two-photon interference.Comment: 4 pages, 4 figure
- …