This study utilizes the Dynamic Conditional Correlation-Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model to investigate the dynamic relationship between Chinese and U.S. stock markets amid t...This study utilizes the Dynamic Conditional Correlation-Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model to investigate the dynamic relationship between Chinese and U.S. stock markets amid the COVID-19 pandemic. Initially, a univariate GARCH model is developed to derive residual sequences, which are then used to estimate the DCC model parameters. The research reveals a significant rise in the interconnection between the Chinese and U.S. stock markets during the pandemic. The S&P 500 index displayed higher sensitivity and greater volatility in response to the pandemic, whereas the CSI 300 index showed superior resilience and stability. Analysis and model estimation suggest that the market’s dependence on historical data has intensified and its sensitivity to recent shocks has heightened. Predictions from the model indicate increased market volatility during the pandemic. While the model is proficient in capturing market trends, there remains potential for enhancing the accuracy of specific volatility predictions. The study proposes recommendations for policymakers and investors, highlighting the importance of improved cooperation in international financial market regulation and investor education.展开更多
The use of food additives in industrial production has the advantage of improving sensory properties, technological quality and extending the shelf life of foods. Among the most widely used additives are antioxidants,...The use of food additives in industrial production has the advantage of improving sensory properties, technological quality and extending the shelf life of foods. Among the most widely used additives are antioxidants, which prevent oxidation, browning and rancidity reactions in foods. However, the strong presence of these additives on the market is not without risks for human health, and should be controlled to guarantee food safety. Analysis of the risks associated with consumption of foods containing these additives requires, among other things, information on the frequency of use of these additives in various consumer products. The aim of this study is therefore to identify the antioxidants present in industrial food products distributed in Dakar. The methodology adopted consists of a qualitative analysis based on the identification of additives from food labels. Investigations were carried out in 9 stores, 4 superettes and 2 supermarkets located in different districts of Dakar. The results revealed the presence of 12 antioxidant additives, dominated by citric acid (53%) and ascorbic acid (29%). These studies have also highlighted the simultaneous use of several antioxidants in the same food product. Moreover, for some artificial antioxidants identified antioxydant such as BHA and BHT, health risks are associated with their consumption. The results of this study open up prospects for the development of information databases on food additives.展开更多
Introduction: Noise is the second leading cause of hearing loss in adults after presbycusis. The objective of this work was to study hearing loss induced by the noise of mills in the markets of Parakou. Methods: This ...Introduction: Noise is the second leading cause of hearing loss in adults after presbycusis. The objective of this work was to study hearing loss induced by the noise of mills in the markets of Parakou. Methods: This was a descriptive and analytical cross-sectional study, conducted from February 3 to June 3, 2021 in the markets of Parakou. It concerned millers and sellers located within a 5 meter radius around the mills and among whom pure-tone audiometry was performed to detect a hearing loss. Subjects with no particular medical health history, under 55 years of age and having been working in these markets since more than 12 months, were included. Results: In this study, 103 subjects were selected, including 43 millers and 61 sellers. Their average age was 29 ± 13 years. The sex ratio was 0.49. The average length of service in the profession was 8 years with the extremes of 3 months and 47 years. They were exposed to noise on average 10 hours per day and 6 days a week. The average duration of weekly noise exposure was 23 h 28 min ± 13 h 32 min with the extremes of 5 h 00 min and 52 h 30 min. The average level of noise exposure was 90 dB with the extremes of 72 and 110 dB. 24 subjects reported symptoms related to noise such as headache, tinnitus, and hearing loss, with respective proportions of 22.33%, 20.39% and 06.80%. The prevalence of noise-related hearing loss was 26.21% (n = 27/103). Subjects with a notch at 4000 Hz and normal Average Hearing Loss (AHL) (20.39%) had a seven-time greater risk of developing noise-induced hearing loss (OR = 6.58;95% CI [2.54 - 18.8], p Conclusion: Hearing loss related to the noise of mills affected both millers and sellers near the mills in markets, hence the importance of regulating mills.展开更多
How to find an effective trading policy is still an open question mainly due to the nonlinear and non-stationary dynamics in a financial market.Deep reinforcement learning,which has recently been used to develop tradi...How to find an effective trading policy is still an open question mainly due to the nonlinear and non-stationary dynamics in a financial market.Deep reinforcement learning,which has recently been used to develop trading strategies by automatically extracting complex features from a large amount of data,is struggling to deal with fastchanging markets due to sample inefficiency.This paper applies the meta-reinforcement learning method to tackle the trading challenges faced by conventional reinforcement learning(RL)approaches in non-stationary markets for the first time.In our work,the history trading data is divided into multiple task data and for each of these data themarket condition is relatively stationary.Then amodel agnosticmeta-learning(MAML)-based tradingmethod involving a meta-learner and a normal learner is proposed.A trading policy is learned by the meta-learner across multiple task data,which is then fine-tuned by the normal learner through a small amount of data from a new market task before trading in it.To improve the adaptability of the MAML-based method,an ordered multiplestep updating mechanism is also proposed to explore the changing dynamic within a task market.The simulation results demonstrate that the proposed MAML-based trading methods can increase the annualized return rate by approximately 180%,200%,and 160%,increase the Sharpe ratio by 180%,90%,and 170%,and decrease the maximum drawdown by 30%,20%,and 40%,compared to the traditional RL approach in three stock index future markets,respectively.展开更多
With the deepening of globalization,the development speed of capital markets is constantly accelerating,presenting a trend of globalization.At the same time,the emergence of multiple forms of trading platforms and div...With the deepening of globalization,the development speed of capital markets is constantly accelerating,presenting a trend of globalization.At the same time,the emergence of multiple forms of trading platforms and diversified financial products further highlights the competitive relationship between security exchanges and other trading platforms.While promoting the transformation of security exchange forms in various countries,it also prompts governments to re-examine the financial regulatory system of securities markets.In this situation,it is very important to research the international financial market and financial regulatory system.This article explores the regulatory issues and countermeasures in the international financial market,intending to promote the stability and healthy development of the international financial market.展开更多
This study investigated the impact of China’s monetary policy on both the money market and stock markets,assuming that non-policy variables would not respond contemporaneously to changes in policy variables.Monetary ...This study investigated the impact of China’s monetary policy on both the money market and stock markets,assuming that non-policy variables would not respond contemporaneously to changes in policy variables.Monetary policy adjustments are swiftly observed in money markets and gradually extend to the stock market.The study examined the effects of monetary policy shocks using three primary instruments:interest rate policy,reserve requirement ratio,and open market operations.Monthly data from 2007 to 2013 were analyzed using vector error correction(VEC)models.The findings suggest a likely presence of long-lasting and stable relationships among monetary policy,the money market,and stock markets.This research holds practical implications for Chinese policymakers,particularly in managing the challenges associated with fluctuation risks linked to high foreign exchange reserves,aiming to achieve autonomy in monetary policy and formulate effective monetary strategies to stimulate economic growth.展开更多
Using VAR-DCC-GARCH model,the literature on commodity price was extended by exploring the co-movement between Chinese nonferrous metal prices and global nonferrous metal prices represented by the nonferrous metal pric...Using VAR-DCC-GARCH model,the literature on commodity price was extended by exploring the co-movement between Chinese nonferrous metal prices and global nonferrous metal prices represented by the nonferrous metal prices from London Metal Exchange(LME).The results show that LME nonferrous metals prices still have a greater impact on Chinese nonferrous metals prices.However,the impact of Chinese nonferrous metals prices on LME nonferrous metals prices is still weak except for lead price.The co-movement of nonferrous metal prices between LME and China presents hysteretic nature,and it lasts for 7-8trading days.Furthermore,the co-movement between LME nonferrous metals prices and Chinese nonferrous metals prices has the characteristics of time-varying,and the correlation of lead prices between LME and China is the more stable than all other nonferrous metals prices.展开更多
Objectives To study the migration of melamine into foods from plastic food packaging materials and dairy product containers commonly used in China. Methods 37 samples were collected from the market. The EU migration t...Objectives To study the migration of melamine into foods from plastic food packaging materials and dairy product containers commonly used in China. Methods 37 samples were collected from the market. The EU migration testing conditions were adopted with distilled water, 3% acetic acid, n-hexane and 15% ethanol being chosen as the simulating solutions. The HPLC method was used to detect melamine. Results No melamine was detected in 15 dairy product containers. Among the 22 plastic samples, 16 of polypropylene, and polycarbonate types had no detectable amount melamine while a low level of melamine was found in 3 of the 6 melamine resin containers. Conclusion Migration of melamine from food packaging materials in China market is in line with the requirements of EU.展开更多
Tail dependence structure model based on Copula theory and extreme value theory (EVT) is constructed to picture the tail correlation of financial time series more exact. The empirical research results show that the ...Tail dependence structure model based on Copula theory and extreme value theory (EVT) is constructed to picture the tail correlation of financial time series more exact. The empirical research results show that the Gumbel Copula can fit the upper and lower tail dependence structures of Shanghai A share index and Shenzhen A share index, and correlation of upper tails of both indices is stronger than that of lower-tails.展开更多
The discussion about smart grid (SG) implementation is mostly focused on pilot projects. These projects are necessary for mapping of particular technical devices of advanced metering management (AMM) which is need...The discussion about smart grid (SG) implementation is mostly focused on pilot projects. These projects are necessary for mapping of particular technical devices of advanced metering management (AMM) which is needed for successful SG and whole functional SG system operation. According to our opinion, for the next step of SG implementation, the participation of effective market design would be quite necessary. In other words, pilot project which is operated regardless to the market conditions and special SG tariff is incomplete and could be irrelevant for further evaluation of feasibility. With regard to above mentioned facts, the detailed cost-benefit-analysis (CBA) is needed to establish the correct methodology for evaluation of SG implementation effectiveness. Related aspects are mentioned and discussed in this paper, in which the particular cost and benefits as well as feedback that occurs as the reaction on implementation are summarized and quantified.展开更多
In the era of big data,there is an urgent need to establish data trading markets for effectively releasing the tremendous value of the drastically explosive data.Data security and data pricing,however,are still widely...In the era of big data,there is an urgent need to establish data trading markets for effectively releasing the tremendous value of the drastically explosive data.Data security and data pricing,however,are still widely regarded as major challenges in this respect,which motivate this research on the novel multi-blockchain based framework for data trading markets and their associated pricing mechanisms.In this context,data recording and trading are conducted separately within two separate blockchains:the data blockchain(DChain) and the value blockchain(VChain).This enables the establishment of two-layer data trading markets to manage initial data trading in the primary market and subsequent data resales in the secondary market.Moreover,pricing mechanisms are then proposed to protect these markets against strategic trading behaviors and balance the payoffs of both suppliers and users.Specifically,in regular data trading on VChain-S2D,two auction models are employed according to the demand scale,for dealing with users’ strategic bidding.The incentive-compatible Vickrey-Clarke-Groves(VCG)model is deployed to the low-demand trading scenario,while the nearly incentive-compatible monopolistic price(MP) model is utilized for the high-demand trading scenario.With temporary data trading on VChain-D2S,a reverse auction mechanism namely two-stage obscure selection(TSOS) is designed to regulate both suppliers’ quoting and users’ valuation strategies.Furthermore,experiments are carried out to demonstrate the strength of this research in enhancing data security and trading efficiency.展开更多
Live poultry markets(LPMs) are crucial places for human infection of influenza A(H7N9 virus).In Yangtze River Delta,LPMs were closed after the outbreak of human infection with avian influenza A(H7N9) virus,and t...Live poultry markets(LPMs) are crucial places for human infection of influenza A(H7N9 virus).In Yangtze River Delta,LPMs were closed after the outbreak of human infection with avian influenza A(H7N9) virus,and then reopened when no case was found.Our purpose was to quantify the effect of LPMs' operations in this region on the transmission of influenza A(H7N9) virus.We obtained information about dates of symptom onset and locations for all human influenza A(H7N9) cases reported from Shanghai,Jiangsu and Zhejiang provinces by May 31,2014,and acquired dates of closures and reopening of LPMs from official media.A two-phase Bayesian model was fitted by Markov Chain Monte Carlo methods to process the spatial and temporal influence of human cases.A total of 235 cases of influenza A(H7N9) were confirmed in Shanghai,Jiangsu and Zhejiang by May 31,2014.Using these data,our analysis showed that,after LPM closures,the influenza A(H7N9) outbreak disappeared within two weeks in Shanghai,one week in Jiangsu,and one week in Zhejiang,respectively.Local authorities reopened LPMs when there was no outbreak of influenza A(H7N9),which did not lead to reemergence of human influenza A(H7N9).LPM closures were effective in controlling the H7N9 outbreak.Reopening of LPM in summer did not increase the risk of human infection with H7N9.Our findings showed that LPMs should be closed immediately in areas where the H7N9 virus is confirmed in LPM.When there is no outbreak of H7N9 virus,LPMs can be reopened to satisfy the Chinese traditional culture of buying live poultry.In the long term,local authorities should take a cautious attitude in permanent LPM closure.展开更多
In this paper the insurer's solvency ratio model with or without jump diffusion process in the presence of financial distress cost is constructed, where an insurer's solvency ratio is characterized by a Markov-modul...In this paper the insurer's solvency ratio model with or without jump diffusion process in the presence of financial distress cost is constructed, where an insurer's solvency ratio is characterized by a Markov-modulated dynamics. By Girsanov's theorem and the option pricing formula, the expected present value of shareholders' terminal payoff is provided.展开更多
Global tea consumption has risen significantly alongside rapid expansion of international trade in recent years.However,few studies have systematically examined the relationship among the major tea markets worldwide.U...Global tea consumption has risen significantly alongside rapid expansion of international trade in recent years.However,few studies have systematically examined the relationship among the major tea markets worldwide.Using weekly data from 2012-2019,this study empirically analyzed the price series of the world’s major black tea auction markets.The estimation results showed that these markets are connected,even though heterogeneities vary.This finding holds not only for regional markets but also for international markets.The findings offer important implications for tea-producing countries with millions of smallholder farmers.展开更多
High-frequency trading(HFT)practices in the global financial markets involve the use of information and communication technologies(ICT),especially the capabilities of high-speed networks,rapid computation,and algorith...High-frequency trading(HFT)practices in the global financial markets involve the use of information and communication technologies(ICT),especially the capabilities of high-speed networks,rapid computation,and algorithmic detection of changing information and prices that create opportunities for computers to effect low-latency trades that can be accomplished in milliseconds.HFT practices exist because a variety of new technologies have made them possible,and because financial market infrastructure capabilities have also been changing so rapidly.The U.S.markets,such as the National Association for Securities Dealers Automated Quote(NASDAQ)market and the New York Stock Exchange(NYSE),have maintained relevance and centrality in financial intermediation in financial markets settings that have changed so much in the past 20 years that they are hardly recognizable.In this article,we explore the technological,institutional and market developments in leading financial markets around the world that have embraced HFT trading.From these examples,we will distill a number of common characteristics that seem to be in operation,and then assess the extent to which HFT practices have begun to be observed in Asian regional financial markets,and what will be their likely impacts.We also discuss a number of theoretical and empirical research directions of interest.展开更多
China formally launched the carbon trading pilots in seven provinces and cities in 2013.Based on the operating situations of international carbon emission trading markets and that in China,this study compares and anal...China formally launched the carbon trading pilots in seven provinces and cities in 2013.Based on the operating situations of international carbon emission trading markets and that in China,this study compares and analyzes the potential risks in the European Union Emission Trading Scheme,California’s cap-and-trade system,and the seven regional carbon trading pilots in China.It mainly recognizes market operation risks,risks of uncertain policy expectation,and risks of uncertain mechanism designs existing in China's carbon trading pilots.The carbon market risks are not good for the formation of rational price signals,making it difficult to guide enterprises on how to make low-carbon technology in-vestments.Such risks also affect the effectiveness and functions of carbon markets,which can lead to the non-achievement of national emission reduction goals.China has launched the national carbon emission trading scheme on December 19,2017.While building the national carbon trading scheme,it is important to fully refer to the experiences of international carbon markets and China's carbon trading pilots apart from strengthening the recognition,control,and supervision of carbon market risks.Doing so can promote the healthy development of China's na-tional carbon trading scheme.展开更多
Supply chain traceability is key to reduce food safety risks,since it allows problems to be traced to their sources. Moreover,it allows regulatory agencies to understand where risk is introduced into the supply chain,...Supply chain traceability is key to reduce food safety risks,since it allows problems to be traced to their sources. Moreover,it allows regulatory agencies to understand where risk is introduced into the supply chain,and offers a major disincentive for upstream agricultural businesses engaging in economically motivated adulteration. This paper focuses on the aquatic supply chain in China,and seeks to understand the adoption of traceability both through an analytical model,and empirical analysis based on data collected through an extensive (largest ever) field survey of Chinese aquatic wholesale markets. The field survey includes 76 managers and 753 vendors,covering all aquatic wholesale markets in Zhejiang and Hunan provinces. The analytical and empirical results suggest that the adoption of traceability among wholesale market vendors is significantly associated with inspection intensity,their individual history of food safety problems,and their risk awareness. The effect of inspection intensity on traceability adoption is stronger in markets which are privately owned than in markets with state/collective ownership. The analysis offers insights into the current state of traceability in China. More importantly,it suggests several hypothesized factors that might affect the adoption of traceability and could be leveraged by regulatory organizations to improve it.展开更多
The annual output of China ' s silica brick amounts up to over 300 thousand tons, which accounts for more than 10% of the total output of silica bricks in the world. Besides satisfying domestic markets , China s s...The annual output of China ' s silica brick amounts up to over 300 thousand tons, which accounts for more than 10% of the total output of silica bricks in the world. Besides satisfying domestic markets , China s silica bricks have been exported to many countries and regions such as Japan, USA etc. In this paper, the situation of silica bricks production, technology, sales and exporting have been described. Also suggestions on improvement of silica bricks quality and exporting, corporation with foreign partners have been put forward in order to win larger market share both at home and abroad.展开更多
文摘This study utilizes the Dynamic Conditional Correlation-Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model to investigate the dynamic relationship between Chinese and U.S. stock markets amid the COVID-19 pandemic. Initially, a univariate GARCH model is developed to derive residual sequences, which are then used to estimate the DCC model parameters. The research reveals a significant rise in the interconnection between the Chinese and U.S. stock markets during the pandemic. The S&P 500 index displayed higher sensitivity and greater volatility in response to the pandemic, whereas the CSI 300 index showed superior resilience and stability. Analysis and model estimation suggest that the market’s dependence on historical data has intensified and its sensitivity to recent shocks has heightened. Predictions from the model indicate increased market volatility during the pandemic. While the model is proficient in capturing market trends, there remains potential for enhancing the accuracy of specific volatility predictions. The study proposes recommendations for policymakers and investors, highlighting the importance of improved cooperation in international financial market regulation and investor education.
文摘The use of food additives in industrial production has the advantage of improving sensory properties, technological quality and extending the shelf life of foods. Among the most widely used additives are antioxidants, which prevent oxidation, browning and rancidity reactions in foods. However, the strong presence of these additives on the market is not without risks for human health, and should be controlled to guarantee food safety. Analysis of the risks associated with consumption of foods containing these additives requires, among other things, information on the frequency of use of these additives in various consumer products. The aim of this study is therefore to identify the antioxidants present in industrial food products distributed in Dakar. The methodology adopted consists of a qualitative analysis based on the identification of additives from food labels. Investigations were carried out in 9 stores, 4 superettes and 2 supermarkets located in different districts of Dakar. The results revealed the presence of 12 antioxidant additives, dominated by citric acid (53%) and ascorbic acid (29%). These studies have also highlighted the simultaneous use of several antioxidants in the same food product. Moreover, for some artificial antioxidants identified antioxydant such as BHA and BHT, health risks are associated with their consumption. The results of this study open up prospects for the development of information databases on food additives.
文摘Introduction: Noise is the second leading cause of hearing loss in adults after presbycusis. The objective of this work was to study hearing loss induced by the noise of mills in the markets of Parakou. Methods: This was a descriptive and analytical cross-sectional study, conducted from February 3 to June 3, 2021 in the markets of Parakou. It concerned millers and sellers located within a 5 meter radius around the mills and among whom pure-tone audiometry was performed to detect a hearing loss. Subjects with no particular medical health history, under 55 years of age and having been working in these markets since more than 12 months, were included. Results: In this study, 103 subjects were selected, including 43 millers and 61 sellers. Their average age was 29 ± 13 years. The sex ratio was 0.49. The average length of service in the profession was 8 years with the extremes of 3 months and 47 years. They were exposed to noise on average 10 hours per day and 6 days a week. The average duration of weekly noise exposure was 23 h 28 min ± 13 h 32 min with the extremes of 5 h 00 min and 52 h 30 min. The average level of noise exposure was 90 dB with the extremes of 72 and 110 dB. 24 subjects reported symptoms related to noise such as headache, tinnitus, and hearing loss, with respective proportions of 22.33%, 20.39% and 06.80%. The prevalence of noise-related hearing loss was 26.21% (n = 27/103). Subjects with a notch at 4000 Hz and normal Average Hearing Loss (AHL) (20.39%) had a seven-time greater risk of developing noise-induced hearing loss (OR = 6.58;95% CI [2.54 - 18.8], p Conclusion: Hearing loss related to the noise of mills affected both millers and sellers near the mills in markets, hence the importance of regulating mills.
文摘How to find an effective trading policy is still an open question mainly due to the nonlinear and non-stationary dynamics in a financial market.Deep reinforcement learning,which has recently been used to develop trading strategies by automatically extracting complex features from a large amount of data,is struggling to deal with fastchanging markets due to sample inefficiency.This paper applies the meta-reinforcement learning method to tackle the trading challenges faced by conventional reinforcement learning(RL)approaches in non-stationary markets for the first time.In our work,the history trading data is divided into multiple task data and for each of these data themarket condition is relatively stationary.Then amodel agnosticmeta-learning(MAML)-based tradingmethod involving a meta-learner and a normal learner is proposed.A trading policy is learned by the meta-learner across multiple task data,which is then fine-tuned by the normal learner through a small amount of data from a new market task before trading in it.To improve the adaptability of the MAML-based method,an ordered multiplestep updating mechanism is also proposed to explore the changing dynamic within a task market.The simulation results demonstrate that the proposed MAML-based trading methods can increase the annualized return rate by approximately 180%,200%,and 160%,increase the Sharpe ratio by 180%,90%,and 170%,and decrease the maximum drawdown by 30%,20%,and 40%,compared to the traditional RL approach in three stock index future markets,respectively.
文摘With the deepening of globalization,the development speed of capital markets is constantly accelerating,presenting a trend of globalization.At the same time,the emergence of multiple forms of trading platforms and diversified financial products further highlights the competitive relationship between security exchanges and other trading platforms.While promoting the transformation of security exchange forms in various countries,it also prompts governments to re-examine the financial regulatory system of securities markets.In this situation,it is very important to research the international financial market and financial regulatory system.This article explores the regulatory issues and countermeasures in the international financial market,intending to promote the stability and healthy development of the international financial market.
文摘This study investigated the impact of China’s monetary policy on both the money market and stock markets,assuming that non-policy variables would not respond contemporaneously to changes in policy variables.Monetary policy adjustments are swiftly observed in money markets and gradually extend to the stock market.The study examined the effects of monetary policy shocks using three primary instruments:interest rate policy,reserve requirement ratio,and open market operations.Monthly data from 2007 to 2013 were analyzed using vector error correction(VEC)models.The findings suggest a likely presence of long-lasting and stable relationships among monetary policy,the money market,and stock markets.This research holds practical implications for Chinese policymakers,particularly in managing the challenges associated with fluctuation risks linked to high foreign exchange reserves,aiming to achieve autonomy in monetary policy and formulate effective monetary strategies to stimulate economic growth.
基金Project(71073177)supported by the National Natural Science Foundation of ChinaProject(12JJ4077)supported by the Natural Science Foundation of Hunan Province of ChinaProject(2012zzts002)supported by the Fundamental Research Funds of Central South University,China
文摘Using VAR-DCC-GARCH model,the literature on commodity price was extended by exploring the co-movement between Chinese nonferrous metal prices and global nonferrous metal prices represented by the nonferrous metal prices from London Metal Exchange(LME).The results show that LME nonferrous metals prices still have a greater impact on Chinese nonferrous metals prices.However,the impact of Chinese nonferrous metals prices on LME nonferrous metals prices is still weak except for lead price.The co-movement of nonferrous metal prices between LME and China presents hysteretic nature,and it lasts for 7-8trading days.Furthermore,the co-movement between LME nonferrous metals prices and Chinese nonferrous metals prices has the characteristics of time-varying,and the correlation of lead prices between LME and China is the more stable than all other nonferrous metals prices.
文摘Objectives To study the migration of melamine into foods from plastic food packaging materials and dairy product containers commonly used in China. Methods 37 samples were collected from the market. The EU migration testing conditions were adopted with distilled water, 3% acetic acid, n-hexane and 15% ethanol being chosen as the simulating solutions. The HPLC method was used to detect melamine. Results No melamine was detected in 15 dairy product containers. Among the 22 plastic samples, 16 of polypropylene, and polycarbonate types had no detectable amount melamine while a low level of melamine was found in 3 of the 6 melamine resin containers. Conclusion Migration of melamine from food packaging materials in China market is in line with the requirements of EU.
基金The National Natural Science Foundation of China (No70331001)
文摘Tail dependence structure model based on Copula theory and extreme value theory (EVT) is constructed to picture the tail correlation of financial time series more exact. The empirical research results show that the Gumbel Copula can fit the upper and lower tail dependence structures of Shanghai A share index and Shenzhen A share index, and correlation of upper tails of both indices is stronger than that of lower-tails.
基金supported in part by the Department of Economics,Management and Humanities,Czech Technical University in Prague under Grant No. GS 10/269/OHK5/3T/13
文摘The discussion about smart grid (SG) implementation is mostly focused on pilot projects. These projects are necessary for mapping of particular technical devices of advanced metering management (AMM) which is needed for successful SG and whole functional SG system operation. According to our opinion, for the next step of SG implementation, the participation of effective market design would be quite necessary. In other words, pilot project which is operated regardless to the market conditions and special SG tariff is incomplete and could be irrelevant for further evaluation of feasibility. With regard to above mentioned facts, the detailed cost-benefit-analysis (CBA) is needed to establish the correct methodology for evaluation of SG implementation effectiveness. Related aspects are mentioned and discussed in this paper, in which the particular cost and benefits as well as feedback that occurs as the reaction on implementation are summarized and quantified.
基金partially supported by the Science and Technology Development Fund,Macao SAR (0050/2020/A1)the National Natural Science Foundation of China (62103411, 72171230)。
文摘In the era of big data,there is an urgent need to establish data trading markets for effectively releasing the tremendous value of the drastically explosive data.Data security and data pricing,however,are still widely regarded as major challenges in this respect,which motivate this research on the novel multi-blockchain based framework for data trading markets and their associated pricing mechanisms.In this context,data recording and trading are conducted separately within two separate blockchains:the data blockchain(DChain) and the value blockchain(VChain).This enables the establishment of two-layer data trading markets to manage initial data trading in the primary market and subsequent data resales in the secondary market.Moreover,pricing mechanisms are then proposed to protect these markets against strategic trading behaviors and balance the payoffs of both suppliers and users.Specifically,in regular data trading on VChain-S2D,two auction models are employed according to the demand scale,for dealing with users’ strategic bidding.The incentive-compatible Vickrey-Clarke-Groves(VCG)model is deployed to the low-demand trading scenario,while the nearly incentive-compatible monopolistic price(MP) model is utilized for the high-demand trading scenario.With temporary data trading on VChain-D2S,a reverse auction mechanism namely two-stage obscure selection(TSOS) is designed to regulate both suppliers’ quoting and users’ valuation strategies.Furthermore,experiments are carried out to demonstrate the strength of this research in enhancing data security and trading efficiency.
文摘Live poultry markets(LPMs) are crucial places for human infection of influenza A(H7N9 virus).In Yangtze River Delta,LPMs were closed after the outbreak of human infection with avian influenza A(H7N9) virus,and then reopened when no case was found.Our purpose was to quantify the effect of LPMs' operations in this region on the transmission of influenza A(H7N9) virus.We obtained information about dates of symptom onset and locations for all human influenza A(H7N9) cases reported from Shanghai,Jiangsu and Zhejiang provinces by May 31,2014,and acquired dates of closures and reopening of LPMs from official media.A two-phase Bayesian model was fitted by Markov Chain Monte Carlo methods to process the spatial and temporal influence of human cases.A total of 235 cases of influenza A(H7N9) were confirmed in Shanghai,Jiangsu and Zhejiang by May 31,2014.Using these data,our analysis showed that,after LPM closures,the influenza A(H7N9) outbreak disappeared within two weeks in Shanghai,one week in Jiangsu,and one week in Zhejiang,respectively.Local authorities reopened LPMs when there was no outbreak of influenza A(H7N9),which did not lead to reemergence of human influenza A(H7N9).LPM closures were effective in controlling the H7N9 outbreak.Reopening of LPM in summer did not increase the risk of human infection with H7N9.Our findings showed that LPMs should be closed immediately in areas where the H7N9 virus is confirmed in LPM.When there is no outbreak of H7N9 virus,LPMs can be reopened to satisfy the Chinese traditional culture of buying live poultry.In the long term,local authorities should take a cautious attitude in permanent LPM closure.
基金Supported by National Natural Science Foundation of China (10671182)Anhui Natural Science Foundation (090416225)+1 种基金Anhui Natural Science Foundation of Universities (KJ2010A037, KJ2010B026)Anhui Natural Science Foundation (10040606Q03)
文摘In this paper the insurer's solvency ratio model with or without jump diffusion process in the presence of financial distress cost is constructed, where an insurer's solvency ratio is characterized by a Markov-modulated dynamics. By Girsanov's theorem and the option pricing formula, the expected present value of shareholders' terminal payoff is provided.
基金supported by the National Natural Science Foundation of China(71773150 and 71934003)。
文摘Global tea consumption has risen significantly alongside rapid expansion of international trade in recent years.However,few studies have systematically examined the relationship among the major tea markets worldwide.Using weekly data from 2012-2019,this study empirically analyzed the price series of the world’s major black tea auction markets.The estimation results showed that these markets are connected,even though heterogeneities vary.This finding holds not only for regional markets but also for international markets.The findings offer important implications for tea-producing countries with millions of smallholder farmers.
文摘High-frequency trading(HFT)practices in the global financial markets involve the use of information and communication technologies(ICT),especially the capabilities of high-speed networks,rapid computation,and algorithmic detection of changing information and prices that create opportunities for computers to effect low-latency trades that can be accomplished in milliseconds.HFT practices exist because a variety of new technologies have made them possible,and because financial market infrastructure capabilities have also been changing so rapidly.The U.S.markets,such as the National Association for Securities Dealers Automated Quote(NASDAQ)market and the New York Stock Exchange(NYSE),have maintained relevance and centrality in financial intermediation in financial markets settings that have changed so much in the past 20 years that they are hardly recognizable.In this article,we explore the technological,institutional and market developments in leading financial markets around the world that have embraced HFT trading.From these examples,we will distill a number of common characteristics that seem to be in operation,and then assess the extent to which HFT practices have begun to be observed in Asian regional financial markets,and what will be their likely impacts.We also discuss a number of theoretical and empirical research directions of interest.
基金the National Key Researchand Development Program of China(2016YFA0602702)the National Natural Science Foundation of China(71673162,71173131,71673019,71273253)Major projects of the Na-tional Social Science Fund of China(18ZDA106).
文摘China formally launched the carbon trading pilots in seven provinces and cities in 2013.Based on the operating situations of international carbon emission trading markets and that in China,this study compares and analyzes the potential risks in the European Union Emission Trading Scheme,California’s cap-and-trade system,and the seven regional carbon trading pilots in China.It mainly recognizes market operation risks,risks of uncertain policy expectation,and risks of uncertain mechanism designs existing in China's carbon trading pilots.The carbon market risks are not good for the formation of rational price signals,making it difficult to guide enterprises on how to make low-carbon technology in-vestments.Such risks also affect the effectiveness and functions of carbon markets,which can lead to the non-achievement of national emission reduction goals.China has launched the national carbon emission trading scheme on December 19,2017.While building the national carbon trading scheme,it is important to fully refer to the experiences of international carbon markets and China's carbon trading pilots apart from strengthening the recognition,control,and supervision of carbon market risks.Doing so can promote the healthy development of China's na-tional carbon trading scheme.
基金The research was funded by the Fundamental Research Funds for the Central Universities,China and ZJU-IFPRI Center for International Development Studiesthe National Planning Office of Philosophy and Social Science of China (19ZDA106).
文摘Supply chain traceability is key to reduce food safety risks,since it allows problems to be traced to their sources. Moreover,it allows regulatory agencies to understand where risk is introduced into the supply chain,and offers a major disincentive for upstream agricultural businesses engaging in economically motivated adulteration. This paper focuses on the aquatic supply chain in China,and seeks to understand the adoption of traceability both through an analytical model,and empirical analysis based on data collected through an extensive (largest ever) field survey of Chinese aquatic wholesale markets. The field survey includes 76 managers and 753 vendors,covering all aquatic wholesale markets in Zhejiang and Hunan provinces. The analytical and empirical results suggest that the adoption of traceability among wholesale market vendors is significantly associated with inspection intensity,their individual history of food safety problems,and their risk awareness. The effect of inspection intensity on traceability adoption is stronger in markets which are privately owned than in markets with state/collective ownership. The analysis offers insights into the current state of traceability in China. More importantly,it suggests several hypothesized factors that might affect the adoption of traceability and could be leveraged by regulatory organizations to improve it.
文摘The annual output of China ' s silica brick amounts up to over 300 thousand tons, which accounts for more than 10% of the total output of silica bricks in the world. Besides satisfying domestic markets , China s silica bricks have been exported to many countries and regions such as Japan, USA etc. In this paper, the situation of silica bricks production, technology, sales and exporting have been described. Also suggestions on improvement of silica bricks quality and exporting, corporation with foreign partners have been put forward in order to win larger market share both at home and abroad.