395 research outputs found
Quantum quenches in a pseudo-Hermitian Chern insulator
We propose to uncover the topology of a pseudo-Hermitian Chern insulator by
quantum quench dynamics. The Bloch Hamiltonian of the pseudo-Hermitian Chern
insulator is defined in the basis of the q-deformed Pauli matrices, which are
related to the representation of the deformed algebras. We show the
bulk-surface duality of the pseudo-Hermitian phases, then further build a
concrete relation between the static band topology and quench dynamics, in
terms of the time-averaged spin textures. The results are also generalized into
a fully nonequilibrium case where the post quench evolution is governed by a
Floquet pseudo-Hermitian Hamiltonian. Furthermore, we propose a possible scheme
to realize the seemingly challenging model in a bilayer lattice and detect the
dynamics with a double-quench protocol.Comment: 9 pages, 6 figure
Transition Matrix Monte Carlo
Although histogram methods have been extremely effective for analyzing data
from Monte Carlo simulations, they do have certain limitations, including the
range over which they are valid and the difficulties of combining data from
independent simulations. In this paper, we describe an complementary approach
to extracting information from Monte Carlo simulations that uses the matrix of
transition probabilities. Combining the Transition Matrix with an N-fold way
simulation technique produces an extremely flexible and efficient approach to
rather general Monte Carlo simulations.Comment: Maui Conference on Statistical Physic
Stationary Light Pulses in Cold Atomic Media
Stationary light pulses (SLPs), i.e., light pulses without motion, are formed
via the retrieval of stored probe pulses with two counter-propagating coupling
fields. We show that there exist non-negligible hybrid Raman excitations in
media of cold atoms that prohibit the SLP formation. We experimentally
demonstrate a method to suppress these Raman excitations and realize SLPs in
laser-cooled atoms. Our work opens the way to SLP studies in cold as well as in
stationary atoms and provides a new avenue to low-light-level nonlinear optics.Comment: 4 pages, 4 figure
Repeated Electroacupuncture Persistently Elevates Adenosine and Ameliorates Collagen-Induced Arthritis in Rats
The aim of this paper was to investigate the effect of repeated electroacupuncture (EA) over 21 days on the adenosine concentration in peripheral blood of rats with collagen-induced arthritis (CIA). Wistar rats were divided into three groups of 6 animals each: sham-control, CIA-control, and CIA-EA. We determined the adenosine concentration in peripheral blood and assessed pathological changes of ankle joints. Quantitative reverse-transcription-polymerase chain reaction was used to determine mRNA levels of ecto-5′-nucleotidase (CD73), adenosine deaminase (ADA), and tumor necrosis factor-alpha (TNF-α). Immunohistochemical staining was used to detect expression of ADA and CD73 in synovial tissue. Repeated EA treatment on CIA resulted in the persistence of high concentrations of adenosine in peripheral blood, significantly reduced pathological scores, TNF-α mRNA concentrations, and synovial hyperplasia. Importantly, EA treatment led to a significant increase in CD73 mRNA levels in peripheral blood but was associated with a decrease of CD73 immunostaining in synovial tissue. In addition, EA treatment resulted in a significant decrease of both ADA mRNA levels in peripheral blood and ADA immunostaining in synovial tissue. Thus, repeated EA treatment exerts an anti-inflammatory and immunoregulatory effect on CIA by increasing the concentration of adenosine. The mechanism of EA action may involve the modulation of CD73 and ADA expression levels
Patchouli Alcohol Modulates the Pregnancy X Receptor/Toll-like Receptor 4/Nuclear Factor Kappa B Axis to Suppress Osteoclastogenesis
The incidence of osteoporosis, which is primarily characterized by plethoric osteoclast (OC) formation and severe bone loss, has increased in recent years. Millions of people worldwide, especially postmenopausal women, suffer from osteoporosis. The drugs commonly used to treat osteoporosis still exist many disadvantages, but natural extracts provide options for the treatment of osteoporosis. Therefore, the identification of cost-effective natural compounds is important. Patchouli alcohol (PA), a natural compound extracted from Pogostemon cablin that exerts anti-inflammatory effects, is used as a treatment for gastroenteritis. However, no research on the use of Patchouli alcohol in osteoporosis has been reported. We found that PA dose-dependently inhibited the receptor activator of nuclear factor kappa-B ligand (RANKL)-induced formation and function of OCs without cytotoxicity. Furthermore, these inhibitory effects were reflected in the significant effect of PA on the NF-κB signaling pathway, as PA suppressed the transcription factors NFATc1 and c-Fos. We also determined that PA activated expression of the nuclear receptor pregnane X receptor (PXR) and promoted the PXR/Toll-like receptor 4 (TLR4) axis to inhibit the nuclear import of NF-κB (p50 and p65). Additionally, PA exerted therapeutic effects against osteoporosis in ovariectomized (OVX) mice, supporting the use of PA as a treatment for osteoporosis in the future
Anapole mediated giant photothermal nonlinearity in nanostructured silicon
Featured with a plethora of electric and magnetic Mie resonances, high index
dielectric nanostructures offer a versatile platform to concentrate
light-matter interactions at the nanoscale. By integrating unique features of
far-field scattering control and near-field concentration from radiationless
anapole states, here, we demonstrate a giant photothermal nonlinearity in
single subwavelength-sized silicon nanodisks. The nanoscale energy
concentration and consequent near-field enhancements mediated by the anapole
mode yield a reversible nonlinear scattering with a large modulation depth and
a broad dynamic range, unveiling a record-high nonlinear index change up to 0.5
at mild incident light intensities on the order of MW/cm2. The observed
photothermal nonlinearity showcases three orders of magnitude enhancement
compared with that of unstructured bulk silicon, as well as nearly one order of
magnitude higher than that through the radiative electric dipolar mode. Such
nonlinear scattering can empower distinctive point spread functions in confocal
reflectance imaging, offering the potential for far-field localization of
nanostructured Si with an accuracy approaching 40 nm. Our findings shed new
light on active silicon photonics based on optical anapoles
Cerebellum Abnormalities in Idiopathic Generalized Epilepsy with Generalized Tonic-Clonic Seizures Revealed by Diffusion Tensor Imaging
Although there is increasing evidence suggesting that there may be subtle abnormalities in idiopathic generalized epilepsy (IGE) patients using modern neuroimaging techniques, most of these previous studies focused on the brain grey matter, leaving the underlying white matter abnormalities in IGE largely unknown, which baffles the treatment as well as the understanding of IGE. In this work, we adopted multiple methods from different levels based on diffusion tensor imaging (DTI) to analyze the white matter abnormalities in 14 young male IGE patients with generalized tonic-clonic seizures (GTCS) only, comparing with 29 age-matched male healthy controls. First, we performed a voxel-based analysis (VBA) of the fractional anisotropy (FA) images derived from DTI. Second, we used a tract-based spatial statistics (TBSS) method to explore the alterations within the white matter skeleton of the patients. Third, we adopted region-of-interest (ROI) analyses based on the findings of VBA and TBSS to further confirm abnormal brain regions in the patients. At last, considering the convergent evidences we found by VBA, TBSS and ROI analyses, a subsequent probabilistic fiber tractography study was performed to investigate the abnormal white matter connectivity in the patients. Significantly decreased FA values were consistently observed in the cerebellum of patients, providing fresh evidence and new clues for the important role of cerebellum in IGE with GTCS
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