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Dengue fever is a mosquito-borne viral disease spread in tropical and subtropical regions caused by the dengue virus (DENV). DENV causes a febrile illness, severe forms including hemorrhagic fevers and shock with fatalities in humans. DENV-2 is frequently associated with severe dengue infections and epidemics. DENV-2 strains from Guangdong, China, have not been characterized to compare the phylogenetics and pathogenicity of different DENV-2 subgenotype strains in both vitro and vivo. A total of 22 patients tested to be DENV-2 positive and were enrolled in this study, 22 complete genomes were obtained by virus isolation and high-throughput sequencing. Phylogenetic and single amino polymorphism (SAP) analysis indicated that two major subgenotypes (A and C) of DENV-2 Cosmopolitan were prevalent in Guangdong in 2018. The apparent change of major subgenotypes of DENV-2 circulating in Guangdong indicated the diversity of DENV-2 strains, including endemic genotype and imported genotype. It alerted the risk of cross-border transmission of DENV. A significant difference in replication rate was observed in C6/36 between different DENV-2 strains, although growth kinetics comparison of different DENV-2 Cosmopolitan subgenotypes showed similar profiles. DENV-2 subgenotypes (A and C) replicated efficiently in IFNAR−/− C57BL/6 mice, and subgenotype A of Cosmopolitan infected mice showed increased weight loss and delayed viral clearance compared with the subgenotype C group. DENV-2 prevalent in Guangdong in 2018 showed apparent genetic and pathogenicity diversity in both vitro and vivo, indicating the necessity of molecular surveillance and exploration of the relationship between its pathogenicity and clinical characteristics.

This paper investigates the timing of Chinese ODI under exchange rate uncertainty by employing the Cox proportional hazards model. Using matched data this paper finds both exchange rate level and volatility are the important determinants, and RMB depreciation and greater volatility will deter ODI. Such adverse effect is found more striking for non-SOEs, firms in the eastern region, and non-exporting firms. With China’s recent exchange rate formation mechanism reform, the impact of exchange rate uncertainty is expected to be stronger. These findings have important implications for China’s exchange rate regime reform and its “Going Global” strategy.

Despite the claims that China has been implementing mercantilism policies to support its exports, recent studies argue that the dominant factor affecting China’s foreign exchange reserves is the precautionary motives. Apart from the economic uncertainty, political instability may be another risk source to consider by those motives. This study intends to empirically investigate how a particular factor originated in the US such as partisan conflict or economic uncertainty explains the foreign exchange reserves hoarding in China. Using SVAR models we find strong evidence suggesting that partisan conflict is positively associated with China’s reserve level, and has a primarily dominant role in predicting the surge in China’s foreign exchange reserves. In contrast, the impact of the US economic uncertainty is found negative and less persistent. The Forecast-error-variance decomposition (FEVD) analysis confirms partisan conflict’s dominant role in explaining the variations in China’s reserve accumulation, in comparison with other variables such as US exports to China and US economic policy uncertainty. The results are robust and consistent under different scenarios and robustness checks. The findings have important policy implications and contribute to the existing literature on the global impacts of US political instability.

This paper examines how news flow affects cross-market volatility spillovers and price discovery process in China’s stock market and index futures market. We find robust evidence confirming dominant predicting power of the stock market in the price discovery process, and presence of asymmetric and persistent volatility effects. The results show that volatility spillovers are bidirectional between stock index futures and spot prices, and news release has significant and positive association with the dynamic conditional correlation between the index spot and the index futures markets. These have important implications for effective hedging and portfolio management decision in emerging markets.

Using the comprehensive RavenPack Dow Jones News Analytics (DJNA) database that captures firm-specific news releases and their sentiment scores at high frequencies, we examine the contemporaneous correlation as well as the lead-lag relation between news and return volatility of major commercial banks listed on the Chinese stock market. Contrary to the Sequential Information Arrival Hypothesis (SIAH), most of the Chinese bank stocks do not exhibit significant lead-lag relations between news and volatility. However, there is substantial evidence that news is strongly correlated with return volatility in all the stocks, consistent with the Mixture of Distributions Hypothesis (MDH). Further analysis based on news sentiment scores suggests that positive news arrivals influence return volatility more strongly, compared with negative news. In addition, there is some evidence indicating that news arrivals contribute to the persistence in return volatility.

Summary COVID-19, caused by SARS-CoV-2, is a virulent pneumonia, with >4,000,000 confirmed cases worldwide and >290,000 deaths as of May 15, 2020. It is critical that vaccines and therapeutics be developed very rapidly. Mice, the ideal animal for assessing such interventions, are resistant to SARS-CoV-2. Here, we overcome this difficulty by exogenous delivery of human ACE2 with a replication-deficient adenovirus (Ad5-hACE2). Ad5-hACE2-sensitized mice developed pneumonia characterized by weight loss, severe pulmonary pathology, and high-titer virus replication in lungs. Type I interferon, T cells and, most importantly, signal transducer and activator of transcription 1 (STAT1) are critical for virus clearance and disease resolution in these mice. Ad5-hACE2-transduced mice enabled rapid assessments of a vaccine candidate, of human convalescent plasma, and of two antiviral therapies (poly I:C and remdesivir). In summary, we describe a murine model of broad and immediate utility to investigate COVID-19 pathogenesis, and to evaluate new therapies and vaccines., An adenoviral transduction-based mouse model that can be infected with SARS-CoV-2 provides a tool to understand host factors involved in viral infection and clearance as well as potential therapeutic modalities.

The Chinese renminbi (RMB) currency system has undergone several major developments in the past two decades, including the adoption of a managed floating system since July 2005, the expansion of an offshore RMB non-deliverable forward (NDF) market, and the relaxation of certain regulatory controls to promote the increased use of the RMB in the region. These developments have sparked intense debate on the potential of RMB internationalization and its pros and cons. In view of these developments, this paper provides a comprehensive analysis of the dynamics of the RMB in both the spot and NDF markets since 2005 by examining the role and significance of the RMB NDF in the price discovery process and in predicting the volatility dynamics of the RMB markets. The results indicate that asymmetric volatility effects are significant for several NDF contract maturities and the spot-NDF correlations are significantly time-varying. Moreover, shocks to the volatility levels are highly persistent. Causality tests on the spot and NDF volatilities further suggest that the NDF markets impact the future fluctuations of the spot market, but the spot market does not have predictive power for the volatility of the NDF markets. Public information flows are found to have a significantly positive impact on the spot-forward conditional correlations. These findings have important implications for market linkages and effective hedging strategies.

This paper studies the role and impact of credit constraints on firm’s export behavior. By using firm-level data from big data matching out of China’s Customs Database and Chinese Industrial Enterprise Database, we study the foreign market entry order strategy of the Chinese exporters and assess the role of credit constraints in the process of internationalization. The results confirm the negative effect of credit constraints on firms’ exporting behavior and entry-time decision. Firms with less credit constraints are more likely to be a pioneer in the foreign market, and those severely credit constrained firms are prevented from doing so because they lack sufficient liquidity. Our robustness tests with different product categories and ownership confirm the evidence. It is also found that a firm’s choice decision for being a pioneer or a follower in exporting each new product-market combination is jointly determined by the firm-level and host-country-level characteristics, and that firms with larger scale, higher productivity, lower production costs and more intense competition are more likely to be pioneers. We also find that the entry timing decision of the followers is influenced by the pioneers’ performance and product category. The results further confirm the existence of crowding out effect and spillover effect between pioneers and followers, and have important policy implications for China’s further financial (credit) market reform and for internationalizing Chinese MNEs.

This paper examines the dynamic relationship among stock illiquidity, corporate social responsibility (CSR) news release and media tone. Using news from 93 news publishers, we investigate the circumstance in which public news release is related to illiquidity by employing the EGARCH-M and the FIGARCH models. The results indicate that CSR news release has a negative and significant impact on stock illiquidity, and media tone effect is asymmetric. Both CSR news and other firm specific general news reduce the volatility persistence and long memory property of stock illiquidity. The sources of news releases matter in impacting stock illiquidity.

This paper examines the impact of public information flows on the volatility of the bilateral Chinese Renminbi–US dollar (RMB–USD) exchange rates in the spot, non-deliverable forward (NDF) and futures markets. By using the comprehensive RavenPack Dow Jones News Analytics database that captures Chinese and US macroeconomic news releases and their sentiment scores at high frequencies, we investigate the circumstances in which public news sentiment is related to the volatility of the above exchange rates. To account for the possibility of different volatility regimes in the RMB–USD volatility, a two-state Regime-Switching EGARCH-in-mean (RS-EGARCH-M) model that incorporates the effects of news sentiment is proposed. Our model suggests that news sentiment has a greater impact on reducing volatility persistence in the low-volatility regime (calm state) for all the NDF and futures exchange rates; in contrast, the impact is greater in the high-volatility regime (turbulent state) for the spot rate. Furthermore, depending on the news sources and sentiment, the marginal effects of news on these exchange rates can vary significantly. In particular, compared with the USD news releases, the RMB news releases have a stronger influence on the RMB–USD volatility. Moreover, the impact of negative news sentiment is greater than that of positive news sentiment. However, the effects of RMB–USD volatility on contemporaneous returns are mostly insignificant. Our RS-EGARCH-M model indicates that the estimated smoothing probability of the RMB–USD spot rate can produce consistent identification of the different economic states arising from changes in the macroeconomic and exchange rate policies of the Chinese government. These findings have important implications for China’s exchange rate regime and the process of RMB internationalization.

This paper examines the democracy-growth nexus and its interactive effect on human development by using cross-national panel data spanning over 20 years incorporating the effect of democratization process. We find evidence that the effect from democracy to human development is nonlinear and varies depending on the levels of growth and democracy. The results confirm that the interaction effect of democracy-growth nexus has a positive impact on human development but the effect is sensitive to democratization process and the level of a country's economic development. It is established that democracy is more crucial in developed countries, whereas economic growth is vital in developing countries. The findings imply that the role of democracy in enhancing human development should not be overemphasized as economic growth is vital in the developing countries.

The current study focused on the Bortala River - a typical inland river located in an oasis of arid area in northwestern China. The sediment and soil samples were collected from the river and drainage basin. Results showed that: (1) the particle size of the sand fraction of the sediments was 78-697 µm, accounting for 78.82% of the total samples; the average concentrations of eight heavy metals fell within the concentration ranges recommended by the Secondary National Standard of China, while the maximum concentrations of Pb, Cd, and Hg exceeded these standards; (2) results from multivariate statistical analysis indicated that Cu, Ni, As, and Zn originated primarily from natural geological background, while Cd, Pb, Hg and Cr in the sediments originated from human activities; (3) results of the enrichment factor analysis and the geo-accumulation index evaluation showed that Cd, Hg, and Pb were present in the surface sediments of the river at low or partial serious pollution levels, while Zn, Cr, As, Ni, and Cu existed at zero or low pollution levels; (4) calculation of the potential ecological hazards index showed that among the eight tested heavy metals, Cd, Pb, Hg, and Cr were the main potential ecological risk factors, with relative contributions of 25.43%, 22.23%, 21.16%, and 14.87%, respectively; (5) the spatial distribution of the enrichment factors (EF(S)), the Geo-accumulation index (I(geo)), and the potential ecological risk coefficient (E(r)(i)) for eight heavy metals showed that there was a greater accumulation of heavy metals Pb, Cd, and Hg in the sediments of the central and eastern parts of the river. Results of this research can be a reference for the heavy metals pollution prevention, the harmony development of the ecology protection and the economy development of the oases of inland river basin of arid regions of China, Central Asia and also other parts of the world.

This paper examines the dynamics of the liquidity premium in the Chinese stock market by adopting a multivariate decomposition approach to measure the individual contributions of various driving forces of the premium (such as firm size, idiosyncratic volatility, and market liquidity betas). By employing a wide range of liquidity measures, we show that liquidity premium is generally significant in the Chinese stock market. Furthermore, this premium is increasing in recent years starting from 2011; this observation is different from the United States market, in which the premium has declined over the years. Moreover, the multivariate decomposition approach highlights several asset pricing factors as the main driving forces of the premium. Based on the Amihud liquidity measure, the decomposition approach indicates that the size factor contributes 45–65% to the liquidity premium. However, the measure based on turnover suggests that idiosyncratic volatility accounts for at least 60% of the liquidity premium. In contrast, the global market liquidity beta does not significantly contribute to the premium. However, there is some evidence that the local market liquidity beta has become more significant in its impact on the premium during the period from 2011 to 2015. Our results imply that the findings on the liquidity premium in the Chinese stock market could be sensitive to the liquidity measure used and period of analysis.

In this study, we first reviewed the current research progress regarding the presence of environmental microplastics (MPs) in environment in China from 2010 to 2019. Results showed that: (1) current research has primarily focused on river and marine environments rather than soils and dusts, mainly located in eastern China, i.e., the Yangtze river, Poyang lake, Dongting lake, Yellow sea, and Bohai sea; (2) the abundance of MPs found in water bodies (sediments) of the rivers in China ranged from 3.9 to 7900 items·m−3 (19.0 × 103-13600.5 × 103 items·km−2), and 20–24300 items·kg−2 (170–5500 × 106 items·km−2) in the sediments, respectively; in lake water the range was 340–8900 items·m−3 (5 × 103-340 × 105 items·km−2) and 8 to 1200 items·m−2/25–300 items·kg−1 in the sediments, respectively; in marine water the range was 0.003–540 items·m−3 (0–380,100 item·km−2) and 1.3–14700 item·kg−1 in the sediments, respectively; in fish, shellfish, and natural planktons from ocean and freshwater, the range was 0–57 items·individuals−1 (0–168 items·g−1); (3) The absorption and toxicological effects of MPs in freshwater and oceans have mainly focused on polyethylene (PE), polypropylene (PP), and polystyrene (PS); (4) the sources of microplastics in soils and dusts primarily come from urban/town activities; for rivers and lakes (estuary), they primarily come from urban activities; for coastal waters, fishing gear and nets, and the maritime activities were the main sources.

This paper examines the conditional time-varying currency betas from five developed markets and four emerging markets. We employ a modified trivariate BEKK-GARCH-in-mean model of Engle and Kroner (1995) to estimate the time-varying conditional variance and covariance of returns of stock index, the world market portfolio and changes in bilateral exchange rate between the US dollar and the local currency. It is found that currency betas are more volatile than those of the world market betas. Currency betas in emerging markets are more volatile than those in the developed markets. Moreover, we find evidence of long-memory in currency betas. The usefulness of time-varying currency betas are illustrated by two applications.

This paper examines the conditional time-varying currency betas from five developed and six emerging financial markets with contagion and spillover effects. We employ a trivariate asymmetric BEKK-type GARCH-in-Mean (MGARCH-M) approach to estimate the time-varying conditional variance and covariance of returns of stock market index, the world market portfolio and bilateral exchange rate between the US dollar and the local currency. The results show that the world market and currency risks are not only priced in the stock markets, but also time-varying. It is found that currency betas are much more volatile than the world market betas, and currency betas in the emerging markets are more volatile than those in the developed markets. We find empirical evidence of contagion effect and spillovers between stock market and foreign exchange market during the recent global financial crisis, and the effect is stronger in the emerging markets than that in the developed markets. Two applications are provided to illustrate the usefulness of time-varying currency betas.

In recent years the Chinese stock market has experienced an astonishing growth and unprecedented development, but is also viewed as one of the most volatile markets, which has been called by many observers a “casino”. This study intends to examine the presence of heteroskedasticity and the leverage effect in the Chinese stock markets, and to capture the dynamics of conditional correlation between returns of China's stock markets and those of the U.S. in a bivariate VC-MGARCH framework. The results show that the leverage effect is significant in these markets during the sample period in 2000–2013, and the conditional correlation between mainland China's and the U.S. stock markets is quite low and highly volatile. The Chinese stock markets are found to be highly regimes persistent. These findings have important implication for investors seeking opportunity of portfolio diversification.

This paper examines the dynamic relationship between firm-level return volatility and public news sentiment. By using the new RavenPack News Analytics ⿿ Dow Jones Edition database that captures over 1200 types of firm-specific and macroeconomic news releases and their sentiment scores at high frequencies, we investigate the circumstances in which public news sentiment is related to the intraday volatility of the constituent stocks in the Dow Jones Composite Average (DJN 65). Two different conditionally heteroskedastic models are employed: the Fractionally Integrated Generalized Autoregressive Conditionally Heteroskedastic (FIGARCH) and the two-state Markov Regime-Switching GARCH (RS-GARCH) models. For most of the DJN 65 stocks, our results confirm the significant impact of firm-specific news sentiment on intraday volatility persistence, even after controlling for the potential effects of macroeconomic news. Compared with macroeconomic news sentiment, firm-specific news sentiment apparently accounts for a greater proportion of overall volatility persistence. Moreover, negative news has a greater impact on volatility than positive news. Furthermore, the results from the RS-GARCH model indicate that news sentiment accounts for a greater proportion of volatility persistence in the high-volatility regime (turbulent state) than in the low-volatility regime (calm state). In-sample forecasting performance and residual diagnostic tests suggest that FIGARCH generally outperforms RS-GARCH.

An important issue for exchange rate pass-through (ERPT) is the extent to which exchange rate changes affect the prices of imported goods and the consumer prices. The objectives of this study are to make a comparative study by exploring the literature relating pass-through for import prices and domestic prices in Australia, China and India. In particular, we test whether the exchange rate pass-through to import prices is complete, estimate the pass-through to consumer price index (CPI) to investigate whether there is any association between the pass-through and the average inflation rate across these countries. A structural VAR model is used to examine the exchange rate pass-through over the period 1990–2011. The impulse responses indicate that exchange rates have less effect in the rising domestic prices in China and India. This will have important policy implication for the monetary authorities.

In this paper a novel all-optical scheme is proposed to reduce fiber nonlinear distortions in high-speed dense wavelength division multiplexed (DWDM) optical fiber communication systems by applying time-domain fractional Fourier transform (FRFT) based on the time–space duality theory. The modulated optical pulses will be pre-distorted by an FRFT module before being launched into fiber links. It has been validated that the pre-distorted signal performs better fiber nonlinearity tolerance compared to that without pre-distortion. Simulation results show that the received bit error rate (BER) is improved by several orders of magnitude for a 40 Gbit/s carrier-suppressed return-to-zero on-off keying (CSRZ-OOK) DWDM system, which can be used in a current 40 Gbit/s system easily to improve the nonlinearity effect tolerance.

Most empirical investigations of the business cycles in the United States have excluded the dimension of asymmetric conditional volatility. This paper analyses the volatility dynamics of the US business cycle by comparing the performance of various multivariate generalised autoregressive conditional heteroskedasticity (GARCH) models. In particular, we propose two bivariate GARCH models to examine the evidence of volatility asymmetry and time-varying correlations concurrently, and then apply the proposed models to five sectors of Industrial Production of the United States. Our findings provide strong evidence of asymmetric conditional volatility in all sectors, and some support of time-varying correlations in various sectoral pairs. This has important policy implications for government to consider the effective countercyclical measures during recessions.

The issue of whether or not to form a monetary union in East Asia remains a hot issue in the study of the East Asian economies. Most of the existing studies apply a framework focusing on the symmetric issue of the fundamental shocks and the extent of correlations by applying the Blanchard and Quah [O.J. Blanchard, D. Quah, The dynamic effects of aggregate demand and supply disturbances, American Economic Review 79 (1989) 655-673] structural vector autoregression (VAR) technique, which includes first-differenced variables in the model and examines only the bilateral relationships. However, the shock symmetry does not necessarily require the co-movements of the real output variables between the countries concerned. The present paper employs the Johansen [S. Johansen, Statistical analysis of cointegration vectors, Journal of Economic Dynamics and Control 12 (1988) 231-254] cointegration approach to check the long-run co-movements of real outputs among the East Asian countries, Japan and the United States to draw some implications about forming a monetary union in the region. The results suggest that some groups of Asian NIEs plus the United States will be potential candidates to form a monetary union. Mainland China is not suggested as a member country of a monetary union with any of the grouped economies. More interestingly, the ASEAN countries alone are not a feasible group to form a monetary union unless Japan is included, which has important implications for the role of Japan towards the formation of a regional monetary union.

This paper examines whether forming an optimum currency area (OCA) is viable for the East Asian region by testing the symmetry of underlying structural shocks. A structural vector autoregression (VAR) method is used to identify the underlying shocks and to examine the correlation in shocks for specified sample periods. Decomposition of the variance of shocks and impulse response analysis are used to examine the size and the speed of adjustments to shocks. The results imply that some sub-regions are potential candidates for forming OCAs, as their shocks are correlated and small, and the economies adjust rapidly to such shocks.

By applying the combined endogenous growth/diffusion model, we find strong and robust evidence of the existence of multiple convergent equilibria across the 10 East Asian economies in 1960–1997. The main conclusion is that, with the assumption of the same source of technology diffusion for all economies, East Asia will have in the long run the same growth rate as that of the leader (Japan), but with two mutually exclusive convergence clubs. This has important implications for an economy when forming its development policy to catch up on its target leaders.

This paper examines the conditional time‐varying currency betas from five developed markets and four emerging markets. We employ a modified trivariate BEKK‐GARCH‐in‐mean model of Engle and Kroner (1995) to estimate the time‐varying conditional variance and covariance of returns of stock index, the world market portfolio and changes in bilateral exchange rate between the US dollar and the local currency. It is found that currency betas are more volatile than those of the world market betas. Currency betas in emerging markets are more volatile than those in the developed markets. Moreover, we find evidence of long‐memory in currency betas. The usefulness of time‐varying currency betas are illustrated by two applications.

This paper examines the conditional time-varying currency betas from five developed markets and four emerging markets. We employ BEKK multivariate GARCH models of Engle and Kroner (1995) to estimate the time-varying conditional variance and covariance of returns of stock index, the world market portfolio and changes in bilateral exchange rate between the US dollar and the local currency. It is found that currency betas are more volatile than those of the world market betas. Currency betas in emerging markets are more volatile than those in the developed markets. Moreover, we find evidence of long-memory in currency betas. The usefulness of time-varying currency betas are illustrated by two applications.

The objective of this paper is to examine the connection between international trade and foreign direct investment (FDI), by comparing some salient features of the Association of Southeast Asian Nations (ASEAN) FDI flows into China with those of FDI flows from the United States and other developed countries. This analysis should be especially instructive in light of the recent macroeconomic model of FDI pioneered by Kojima on the relationship between a country's comparative advantage and its outward direct investment. We postulate that the changing patterns of the ASEAN countries' comparative advantage and other macro-level factors play an important role in motivating firms to venture in China. Similarity of trade structure and lack of complementarity of the Chinese and ASEAN economies limit the absorptive capacity of each other's products, which further challenges the entrepreneurs of the ASEAN countries to a high commitment of direct investment into China.

It has been a hot debit whether a monetary union is feasible in the East Asian region. Most of the existing studies focus on the symmetric issue of the fundamental shocks and the extent of correlation by applying the Blanchard and Quah (1989) structural vector autoregression (VAR) technique, which includes the first-differenced variables in the model and examines only the bilateral relationship. However, the shock symmetry does not necessarily mean the co-movements of the real output variables (common business cycles) between the countries concerned. The present paper employs the Johansen (1988) cointegration test to check the long-run co-movements of real outputs and also conducts the Vahid and Engle (1993) common feature test to detect the short-term common business cycles. The novelty of this paper is twofold. First, whereas the structural VAR approach considers shocks correlation bilaterally, we use a multivariate VAR framework to allow for the relationships within a specific group of countries. Second, we employ the cointegration technique to examine both the long-run and the short-run dynamics of the real variables to determine the suitability and costs of forming a monetary union in the region.