Comparison of Three Volatility Forecasting Models

Although forecasting volatility is an important component of assessing financial risks, it is difficult for many investors because most methods require advanced mathematical knowledge. However, there are two types of time-series models, generalized autoregressive conditional heteroskedasticity (GARCH) (1,1) and exponentially weighted moving average (EWMA), that can be used by investors with only basic training. Furthermore, the implied volatility indexes launched by the Chicago Board Options Exchange (CBOE) provide investors with a direct assessment of market volatility. However, it is unclear which of these three models is best for individual investors. To find out which of these three is the best forecasting method for investors to use, this research first checks whether implied volatility indexes can provide more accurate forecasts than GARCH (1,1) and EWMA by comparing the predictive ability of 11 implied volatility indexes (namely, VIX, VXST, VIX3M, VXMT, VXO, VXD, RVX, VXN, VFTSE, VHSI, and VHSI) with that of GARCH (1,1) and EWMA for the underlying stock indexes. Second, this research focuses on comparing in detail the volatility forecasting ability of GARCH (1,1) and that of EWMA to find which is the best method when volatility indexes are not available or volatility indexes are not good to use. The root mean-square error (RMSE) is used to examine the predictive ability of the three volatility forecasting methods mentioned and the results show that the implied volatility indexes perform better than the GARCH (1,1) and EWMA models for stock indexes in most situations. Additionally, it is shown that GARCH (1,1) has stronger forecasting powers than EWMA for stock indexes. Overall, most implied volatility indexes can be regarded as good forecasts of future volatility to be used by investors in the markets. If an implied volatility index is unavailable or not suitable for a particular case, averaging the forecasts from GARCH (1,1) and EWMA would be a good way to ensure investors get relatively accurate forecasts.No embargoAcademic Major: Economics - BusinessAcademic Major: Financial Mathematic

A calcium ion-imprinted porous film prepared from a cellulose-alginate composite

An ion-imprinted (IIP) film has been successfully prepared in this work. Firstly, mixture solution of cellulose and alginate was obtained by dissolving those polymers in a NaOH/urea aqueous solution. Then the mixture solution was cast onto glass plate and coagulated in CaCl2 aqueous solution bath to prepare a composite film. The matrix of the film was further fixed by cross-linking. Finally, the chelated Ca2+ in the matrix was removed to obtain the IIP film. The IIP film was characterized to show satisfactory mechanical properties, and to exhibit porous mesh network microstructure. The equilibrium swelling ratio of the IIP film was determined to be 700?%. The IIP film was immersed into Ca2+, Ca2+/Cu2+, Ca2+/Zn2+ and Ca2+/Mg2+ solutions to check the adsorption behavior, respectively. The results indicate that the IIP film displayed highly selective Ca2+ recognition, and the presence of additional cations had little effect on the Ca2+ recognition. Thus prepared Ca2+ imprinted film have potential applications in fields such as hard water softening, and Ca2+ enrichment or recognition

Structural and Functional Insights into an Archaeal Lipid Synthase

The UbiA superfamily of intramembrane prenyltransferases catalyzes an isoprenyl transfer reaction in the biosynthesis of lipophilic compounds involved in cellular physiological processes. Digeranylgeranylglyceryl phosphate (DGGGP) synthase (DGGGPase) generates unique membrane core lipids for the formation of the ether bond between the glycerol moiety and the alkyl chains in archaea and has been confirmed to be a member of the UbiA superfamily. Here, the crystal structure is reported to exhibit nine transmembrane helices along with a large lateral opening covered by a cytosolic cap domain and a unique substrate-binding central cavity. Notably, the lipid-bound states of this enzyme demonstrate that the putative substrate-binding pocket is occupied by the lipidic molecules used for crystallization, indicating the binding mode of hydrophobic substrates. Collectively, these structural and functional studies provide not only an understanding of lipid biosynthesis by substrate-specific lipid-modifying enzymes but also insights into the mechanisms of lipid membrane remodeling and adaptation

Correction:Structural and Functional Insights into an Archaeal Lipid Synthase

(Cell Reports 33, 108294-1–9.e1–e4; October 20, 2020) In the originally published version of this article, the supplemental information file containing Figures S1–S7 and Table S1 was inadvertently removed. The complete supplemental information file is now included with the paper online. The production team regrets this error

中国优质基础教育资源空间格局形成机制及综合效应

Education is not only important for strengthening a country's population quality and comprehensive power but key in reshaping the "man-land" relations in a country. This article reviews studies on the distribution of educational resources in both Chinese and Anglophone literature and summarizes the research gaps in the Chinese literature, which include but are not limited to the downplay of the analysis of mechanism and comprehensive effects of the spatial structure of educational resources. Employing different map-making technologies and mechanism-analysis methods, this article dives into three findings. First, though spatial features are slightly different between primary school level and middle school level, eastern regions generally have higher quality educational resources than western regions. In addition, urban agglomeration, including Beijing-Tianjin-Hebei, Shanghai-Ningbo-Hangzhou, and the Pearl River Delta, have an advantage in attracting and cultivating high-quality educational resources. Second, the quantity of high-quality primary school resources is positively correlated with annual per capita disposable income of urban households and number of full-time primary school teachers. The quantity of high-quality middle school resources is positively correlated with the comprehensive economic and social performance of the city. Third, when affected by multiple mechanisms, the spatial structure of China's high-quality educational resources is dynamic and deeply intertwines with the interrelations between cities as well as between the societies within each city. This article contributes both to the understanding of the unequal spatial structure of high-quality educational resources in China and to the analysis of complex socio-political effects on this transforming structure. Its findings encourage further research on the connection between the spatial structure of a region's educational resources and its cooperation and geopolitics as well as on the resulting social mobility among different social strata. Study limitations include: place-related elements, such as local political resources, were not sufficiently considered when selecting factors; there is a lack of longitudinal analysis; and not enough attention is paid to the combination of number-based data and geo-information-based data in analyses

Genome-Wide Analysis of Coding and Long Non-Coding RNAs Involved in Cuticular Wax Biosynthesis in Cabbage (Brassica oleracea L. var. capitata)

Cuticular wax is a mixture of very long chain fatty acids (VLCFAs) and their derivatives, which determines vital roles for plant growth. In cabbage, the cuticular wax content of leaf blades is an important trait influencing morphological features of the head. Understanding the molecular basis of cuticular wax biosynthesis can help breeders develop high quality cabbage varieties. Here, we characterize a cabbage non-wax glossy (nwgl) plant, which exhibits glossy green phenotype. Cryo-scanning electron microscope analysis showed abnormal wax crystals on the leaf surfaces of nwgl plants. Cuticular wax composition analyzed by GC-MS displayed severely decreased in total wax loads, and individual wax components in nwgl leaves. We delimited the NWGL locus into a 99-kb interval between the at004 marker and the end of chromosome C08 through fine mapping. By high-throughput RNA sequencing, we identified 1247 differentially expressed genes (DEGs) and 148 differentially expressed lncRNAs in nwgl leaves relative to the wild-type. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the DEGs and cis-regulated target genes for differentially expressed lncRNAs were significantly enriched in wax and lipid biosynthetic or metabolic processes. Our results provide the novel foundation to explore the complex molecular basis of cuticular wax biosynthesis

Impact of Polymyxin Resistance on Virulence and Fitness among Clinically Important Gram-Negative Bacteria

Humanity is facing an enormous and growing worldwide threat from the emergence of multi-drug-resistant (MDR) Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii. Polymyxin B and E (colistin) constitute the last-line therapies for treating MDR Gram-negative bacteria. Polymyxin is a cationic antibacterial peptide that can destroy the outer membrane of Gram-negative bacteria. With the increasing clinical application of polymyxin, however, there have been many reports of the occurrence of polymyxin-resistant Gram-negative bacteria. This resistance is mainly mediated by the modification or complete loss of lipopolysaccharide (LPS). LPS is also a virulence factor of Gram-negative bacteria, and alterations of LPS may correlate with virulence. Although it is generally believed that the biological costs associated with drug resistance may enable benign susceptible bacteria to overcome resistant bacteria when antibiotic pressure is reduced, some studies have shown that polymyxin-resistant bacteria are associated with higher virulence and greater fitness compared with their susceptible counterparts. To predict the development of polymyxin resistance and evaluate interventions for its mitigation, it is important to understand the relative biological cost of polymyxin resistance compared with susceptibility. The impact of polymyxin resistance mechanisms on the virulence and fitness of these three Gram-negative bacteria are summarized in this review

The response of CD27+CD38+ plasmablasts, CD24hiCD38hi transitional B cells, CXCR5−ICOS+PD-1+ Tph, Tph2 and Tfh2 subtypes to allergens in children with allergic asthma

Abstract Background Allergic asthma is a type I allergic reaction mediated by serum Immunoglobulin E (IgE). B cell-mediated humoral immune response to allergens in the pathophysiology of allergic asthma have not been thoroughly elucidated. Peripheral helper T cells (Tph) and follicular helper T cells (Tfh) promote B cell differentiation and antibody production in inflamed tissues. Objective To investigate the roles of B cell subsets, Tph cell subsets and Tfh cell subsets in allergic immune responses. Methods Circulating B cell subsets, Tph cell subsets and Tfh cell subsets in 33 children with allergic asthma and 17 healthy children were analyzed using multicolor flow cytometry. The level of serum total IgE was also assessed. Results Our study found that CD27+CD38+ plasmablasts and CD24hiCD38hi transitional B cells increased and were correlated with serum total IgE level, CD27− naive B cells and CD24hiCD27+ B cells decreased in children with allergic asthma. CXCR5− Tph, CXCR5−ICOS+ Tph, CXCR5−ICOS+PD-1+ Tph, CXCR5+ICOS+ Tfh and CXCR5+ICOS+PD-1+ Tfh increased in children with allergic asthma. Further analysis showed increased Tph2, Tph17, Tfh2 and Tfh17 subtypes while decreased Tph1 and Tfh1 subtypes in children with allergic asthma. Most interestingly, Tph2 or Tfh2 subtypes had a positive correlation with serum total IgE level. Conclusion Overall, these results provide insight into the allergens elicited B, Tph or Tfh cell response and identify heretofore unappreciated CD24hiCD38hi transitional B cells, CD24hiCD27+ B cells, CXCR5− Tph, CXCR5−ICOS+PD-1+ Tph, Tph2 subtypes and Tfh2 subtypes response to allergens

Haplotypic polymorphisms and forensic applications in Chinese Hunan Han population based on a series of Y-STR loci: a perspective of paternal inheritance

Background Hunan, a multinational province in China, possesses more than fifty ethnic groups, such as the Han, Yao, Tujia, Miao, and so on. Aims To evaluate the forensic efficiency of the novel panel and investigate the genetic relationships between Hunan Han population and 12 other reference populations from China. Subjects and methods Haplotypic data of 153 unrelated males of Hunan Han population were investigated using the AGCU Y SUPP Plus amplification system containing 27 Y-chromosomal short tandem repeat (STR) loci. Forensic parameters were calculated to evaluate the application efficiency of this panel in Hunan Han population. Results Haplotype diversity, discrimination capability, and match probability values were 0.9999999977, 1.0000, and 0.0065, respectively. Pairwise fixation index values demonstrated that the minimal genetic differentiation (0.0073) was found between Hunan Han population and Hunan Yao group, while the maximal genetic differentiation (0.0651) was observed between Hunan Han and Guangxi Yao group from the perspective of the patrilineal DNA analysis. Conclusions The haplotype distributions of 27 Y-STR loci in Hunan Han population exhibited remarkable polymorphisms. Moreover, this panel has potential advantages for the forensic applications regarding family investigations, paternity testing of the paternal line, and population genetics

Regional characteristics and spatial correlation of haze pollution: Interpretative system analysis in cities of Fenwei Plain in China.

Urban agglomeration is an important model for promoting global economic development and has made important contributions to global economic integration. However, as the core area of urbanization and industrialization, urban agglomerations also contribute to air pollutant emissions primarily due to the agglomeration of population and industry. The mutual influence of air pollution between different cities in urban agglomerations has brought significant challenges to global environmental governance. The Fenwei Plain is one of the most severely polluted areas in China. We collected daily average PM2.5 concentration data of 11 cities in the Fenwei Plain, China in 2019. We then developed an interpretive structural model to statistically analyze the spatial correlation and hierarchical transmission of haze pollution between the 11 cities. The results showed that haze pollution has a strong systematic correlation between the 11 cities, and a regional haze pollution community has formed throughout the region. Haze pollution also exhibits evident transmission and spatial correlations between the cities. The transmission starts from Baoji and ends at Sanmenxia, with mutual interactions between the cities of Xi'an, Xianyang, Weinan, Tongchuan, Jinzhong, Lvliang, Linfen, Yuncheng, and Luoyang. Thus, air pollution prevention and control in the Fenwei Plain should consider the spatial correlation of haze pollution between different cities, especially in autumn and winter, and should rationally be implemented in key urban cluster areas. We recommend building a coordinated governance between cities to improve the overall air quality. Our findings shed a light for coordinated pollution management in urban agglomerations worldwide