21,159 research outputs found
Fermions Tunneling from Higher-Dimensional Reissner-Nordstr\"om Black Hole: Semiclassical and Beyond Semiclassical Approximation
Based on semiclassical tunneling method, we focus on charged fermions
tunneling from higher-dimensional Reissner-Nordstr\"{o}m black hole. We first
simplify the Dirac equation by semiclassical approximation, and then a
semiclassical Hamilton-Jacobi equation is obtained. Using the Hamilton-Jacobi
equation, we study the Hawking temperature and fermions tunneling rate at the
event horizon of the higher-dimensional Reissner-Nordstr\"{o}m black hole
spacetime. Finally, the correct entropy is calculation by the method beyond
semiclassical approximation.Comment: 7 page
Domain wall brane in a reduced Born-Infeld- theory
The Born-Infeld theory is reduced from the Born-Infeld determinantal
gravity in Weitzenb\"ock spacetime. We investigate a braneworld scenario in
this theory and obtain an analytic domain wall solution by utilizing the
first-order formalism. The model is stable against the linear tensor
perturbation. It is shown that the massless graviton is localized on the brane,
but the continuous massive gravitons are non-localized and will generate a tiny
correction with the behavior of to the Newtonian potential.
The four-dimensional teleparallel gravity is recovered as an effective infrared
theory on the brane. As a physical application, we consider the
(quasi-)localization property of spin-1/2 Dirac fermion in this model.Comment: 9 pages, 2 figures, published versio
Mechanism of PEDF promoting the proliferation of lens epithelial cells in human eyes
AbstractObjectiveTo investigate the regulation effect of pigment epithelium-derived factor (PEDF) on the growth of human lens endothelial cells (LECs) and related mechanisms in vivo and in vitro.MethodsIn the part of in vivo study, 82 eyes of 82 patients with age-related cataract were included to collect the central lens anterior capsule (diameter at 5.0–5.5 mm) with the informed consent of surgery for patients. The selected specimens were divided into the LECs low density group and high density group with 20 specimens for each group based on hematoxylin and eosin staining results. The relative expression level of PEDF mRNA in LECs was detected by reverse transcription PCR. In the part of in vitro study, LEC line (HLE-B3) was cultured and 50 ng/mL PEDF was added in media for 72 h in PEDF culture group, while normally cultured cells were used as the control group. The percentage of LECs at G0 and S phases and apoptotic rate of cells were assayed by using flow cytometry with annexin Ⅴ-FITC/7-AAD double staining method. Intracellular expression of vascular endothelial growth factor (VEGF) mRNA was detected by real-time fluorescence quantitative PCR.ResultsThe central anterior subcapsular LECs density and relative expression level of PEDF mRNA were lower than those of high density group. There were no significant differences between two groups (P = 0.168). The apoptotic rate in the PEDF culture group was significantly reduced in comparison with the control group (P < 0.001). In addition, the expression level of VEGF mRNA was lower in the PEDF culture group compared with the control group (P < 0.001).ConclusionsIn human eyes, PEDF may function as cytotropic factor to promote survival of LECs through anti-apoptosis and reducing-expression of VEGF. Decrease of PEDF content in LECs probably modulates the pathophysiological process of lens cells and further cataractogenesis
Dimensionless ratios: characteristics of quantum liquids and their phase transitions
Dimensionless ratios of physical properties can characterize low-temperature
phases in a wide variety of materials. As such, the Wilson ratio (WR), the
Kadowaki-Woods ratio and the Wiedemann\--Franz law capture essential features
of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases
of many-body interacting multi-component quantum liquids in one dimension (1D)
can be described by WRs based on the compressibility, susceptibility and
specific heat associated with each component. These WRs arise due to additivity
rules within subsystems reminiscent of the rules for multi-resistor networks in
series and parallel --- a novel and useful characteristic of multi-component
Tomonaga-Luttinger liquids (TLL) independent of microscopic details of the
systems. Using experimentally realised multi-species cold atomic gases as
examples, we prove that the Wilson ratios uniquely identify phases of TLL,
while providing universal scaling relations at the boundaries between phases.
Their values within a phase are solely determined by the stiffnesses and sound
velocities of subsystems and identify the internal degrees of freedom of said
phase such as its spin-degeneracy. This finding can be directly applied to a
wide range of 1D many-body systems and reveals deep physical insights into
recent experimental measurements of the universal thermodynamics in ultracold
atoms and spins.Comment: 12 pages (main paper), (6 figures
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