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Examining Stock Volatility in the Segmented Chinese Stock Markets: A SWARCH Approach
ZHUO QIAO,WEIWEI QIAO,Wing-Keung Wong 연세대학교 동서문제연구원 2010 Global economic review Vol.39 No.3
This study adopts the SWARCH model to examine the volatile behavior and volatility linkages among the four major segmented Chinese stock indices.We find strong evidence of a regime shift in the volatility of the four markets, and the SWARCH model appears to outperform standard generalized autoregressive conditional heteroskedasticity (GARCH) family models. The evidence suggests that, compared with the A-share markets, B-share markets stay in a high-volatility state longer and are more volatile and shift more frequently between high- and low-volatility states. In addition, the relative magnitude of the high-volatility compared with that of the low-volatility state in the B-share markets is much greater than the case in the two A-share markets. B-share markets are found to be more sensitive to international shocks, while A-share markets seem immune to international spillovers of volatility. Finally, analyses of the volatility spillover effect among the four stock markets indicate that the A-share markets play a dominant role in volatility in Chinese stock markets.
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ZHUO QIAO,WEIWEI QIAO,Wing-Keung Wong 연세대학교 동서문제연구원 2011 Global economic review Vol.40 No.3
Many researchers have investigated the existence of day-of-the-week effects in different financial markets. However, they have usually adopted a parametric approach, which is known to have a few limitations. This paper adopts a non-parametric stochastic dominance (SD) approach to examine the day-of-the-week effects in Chinese stock markets. In contrast to the extensive evidence of day-of-the-week effects disclosed by a parametric mean-variance (MV) approach, our SD tests show that the day-of-the-week effect is much weaker. We find that there are only Wednesday effects in Chinese A-share and B-share stock markets.
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Structural evolution of the thermal conversion products of modified coal tar pitch
Qi Li,Dongyun Han,Haiyan Qiao,Weiwei Shi,Yuqi Zhang,Zubin Cao 한국탄소학회 2023 Carbon Letters Vol.33 No.1
Coal tar pitch is a product with high carbon content and aromatic compounds. Modified coal tar pitch is a high quality raw material for the preparation of intermediate phase pitch, needle coke, carbon microspheres, et al. In this paper, modified coal tar pitch was used as raw material, nitrogen was used as protective gas, and thermal conversion was carried out at constant temperatures (370, 390, 410, 420 °C). Polarized light microscopy, SEM, elemental analysis, FTIR spectroscopy, Raman spectroscopy and XRD diffraction combined with split-peak fitting were used to characterize the microstructures of the thermal transformation products. The results showed that the Iar and CH3/ CH2 contents of the products increased with the gradual increase of the thermal conversion temperature, and the aromatic content increased. And the higher the temperature at the same heating rate, the more the ideal graphite microcrystal content, and the defective graphite microcrystals are converted into ideal graphite microcrystals during the thermal conversion process. When the reaction temperature exceeds 390 °C, the microstructure of the thermal transformation products is anisotropic spheres, and the small spheres fuse with each other and tend to be basin-like and mosaic structure as the temperature increases.
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Qiang Feng,Shenggang Fu,Chengxiang Wang,Weiwei Liu,Ying Wang,Weiguo Qiao 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.9
There is an increasing trend of tunnel infrastructure construction in cold regions due to the advance of a western development strategy. To reduce the frost damage sustained by a tunnel, it is important to consider the mechanical properties of frost heave in the surrounding rock by analyzing the anisotropic frost heave of a cold-region tunnel. This paper elaborates on the behavior of anisotropic frost heave in the rock surrounding a cold-region tunnel, and the coefficient of displacement relief is adopted to indirectly quantify the influence of the tunnel construction process. The analytical elasto-plastic solutions of the stress and deformation in the surrounding rock are derived with Drucker-Prager criteria (hereinafter referred to as the D-P criteria) by modifying the constitutive equation for the frozen surrounding rock. Finally, an example is given to obtain the influence law of the distribution of stress and deformation in the surrounding rock. The results indicate that the plastic radius and frost force calculated by considering isotropic frost heave are greater than those obtained by considering anisotropic frost heave. The influence of the related parameters also analyzed. Some useful insights are provided for future numerical simulations and the design and construction of cold-region tunnels.
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Yehui Wu,Jing Li,Mengfan Qiao,Dan Meng,Qingling Meng,Jun Qiao,Xingxing Zhang,Lixia Wang,Kuojun Cai,Jinsheng Zhang,Zaichao Zhang,Weiwei Yu,Xuepeng Cai 대한수의학회 2019 Journal of Veterinary Science Vol.20 No.6
As an important zoonotic pathogen, Staphylococcus aureus (S. aureus) infection has led to serious mastitis and endometritis in infected dairy cows. HereIn this study, a total of 164 strains of S. aureus were isolated from dairy cows in Xinjiang Province, China, and subjected to assays to determine of drug susceptibility and biofilm (BF) formation ability. The eEnterotoxin-related genes were detected, and then the transcription levels of genes related to BF formation were also determined by using reverse transcription-quantitative polymerase chain reactionPCR. Moreover, the pathogenicity of these isolates with different BF formation abilities was determined via by measuring their hemolysis activity, half lethal dose (LD50) and organ bacterial load, respectively. The results showed that 83.4 % of S. aureus isolates could form BF. Among them, 40.8 % of the strains had weak BF formation ability, and most strains with a strong BF formation ability were ica gene carriers. The S. aureus isolates displayed multidrug resistance and their drug resistance was positively correlated with their BF formation ability. Moreover, 96.3 % of the S. aureus isolates carried enterotoxin genes. Among them, the detection rates of the novel enterotoxin genes were higher than thoseat of conventional enterotoxin genes. Furthermore, the isolates with a strong BF formation ability had higher LD50 but lower hemolysis ability and organ bacterial load than thoseat of the isolates with weak or no BF ability. However, those isolates without BF ability caused produced more severe pathological changes than thoseat of the isolates with strong BF formation ability. These findings suggested that higher frequencies of BF ability and presence of novel enterotoxin genes were are important characteristics of S. aureus isolates from dairy cows in Xinjiang Province, China, and such isolateswhich may posed potential threats to food safety.
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