4,744 research outputs found

    Relativistic symmetry breaking in light kaonic nuclei

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    As the experimental data from kaonic atoms and KNK^{-}N scatterings imply that the KK^{-}-nucleon interaction is strongly attractive at saturation density, there is a possibility to form KK^{-}-nuclear bound states or kaonic nuclei. In this work, we investigate the ground-state properties of the light kaonic nuclei with the relativistic mean field theory. It is found that the strong attraction between KK^{-} and nucleons reshapes the scalar and vector meson fields, leading to the remarkable enhancement of the nuclear density in the interior of light kaonic nuclei and the manifest shift of the single-nucleon energy spectra and magic numbers therein. As a consequence, the pseudospin symmetry is shown to be violated together with enlarged spin-orbit splittings in these kaonic nuclei.Comment: 15 pages, 7 figure

    VLBI imaging of M81* at 3.4 mm with source-frequency phase-referencing

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    We report on the first VLBI image of the M81 nucleus (M81*) at a wavelength of 3.4 mm, obtained with the source-frequency phase-referencing (SFPR) technique. Thanks to the SFPR calibration, the coherent integration time could be eventually increased by more than an order of magnitude, which enabled the detection of fringes at the level of 45 mJy beam-1 with a dynamic range higher than 130:1. This paves the way toward future mm/sub-mm VLBI observations of weaker sources. From the analysis of the M81* visibilities, a core size of ~50 uas at 3.4 mm was estimated. This follows the power-law relationship with wavelength lambda^0.88, reported previously at lower frequencies. These results constrain the core size (at 3.4 mm) to a minimum of ~80 Schwarzschild radii of M81*.Comment: 10 pages, 5 figures,accepted by ApJ Lette

    Cardioprotective effects of the total flavonoids of Polygonum cuspidatum Sieb. et Zucc. Root extract on experimental myocardial infarction in mice

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    Purpose: To study the cardioprotective effects of the total flavonoids from the roots of Polygonum cuspidatum Sieb. et Zucc. (FHZ) on experimental myocardial infarction in mice.Methods: Ultrasonic-assisted extraction of FHZ was optimized by response surface methodology (RSM) to obtain a higher extraction yield. Myocardial infarction (MI) was established by ligation of the left anterior descending (LAD) branch of the coronary artery in mice. Cardiac troponin T (cTnT), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), lipid peroxide (LPO), malondialdehyde (MDA) and superoxide dismutase (SOD) levels in the serum of mice were assessed by enzyme-linked immunosorbent assay. Furthermore, myocardial infarction size (MIS) was examined by Masson’s Trichrome staining on heart tissues.Results: Optimum extraction conditions of FHZ were as follows: an ethanol concentration of 69.03 %, a liquid-solid ratio of 27.14 g/mL and an extraction time of 30.30 min. The obtained extraction conditions were proven to be accurate and reliable. After treatment with FHZ for 3 and 7 days, the serum level of cTnT in MI mice decreased significantly. Also, the serum levels of CPK, LPO, MDA, and LDH were significantly decreased while SOD level increased in MI mice treated with FHZ. Furthermore, after treatment with FHZ for two weeks, the MIS of MI mice decreased (p < 0.01).Conclusion: RSM is a useful tool to optimize the ultrasonic-assisted extraction conditions for FHZ. Furthermore, FHZ possesses significant cardioprotective effects on experimental myocardial infarction in mice and thus may find application in the clinical management of myocardial infarction.Keywords: Polygonum cuspidatum, Flavonoids, Response surface methodology, Myocardial infarction, Cardioprotectiv

    Constructing Media-based Enterprise Networks for Stock Market Risk Analysis

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    Stock comovement analysis is essential to understand the mechanism of stock markets. Previous studies focus on the comovement from the perspectives of fundamentals or preferences of investors. In this article, we propose a framework to explore the comovements of stocks in terms of their relationships in Web media. This is achieved by constructing media-based enterprise networks in terms of the co-exposure in news reports of stocks and mutual attentions among them. Our experiments based on CSI 300 listed firms show the significant comovements of stocks brought out by their behaviors in Web media. Furthermore, utilizing media based enterprise networks can help us identify the most influential firms which can stir up the stock markets
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