毛竹水溶性多糖提取工艺的优化及结构表征

采用响应面法优化毛竹水溶性多糖的提取工艺,分析其成分,并进行结构表征。研究结果表明,优化的毛竹多糖(BSP)提取条件为:料液比1∶27(g/mL)、提取温度78 ℃、提取时间4 h,该条件下BSP提取率为(5.18±0.07)%,提取物中多糖含量为(72.14±0.02)%,糖醛酸含量为(9.76±0.03)%;BSP具有酸性多糖典型的官能团特征吸收峰,其单糖组成及摩尔比为n_甘露糖∶n_葡萄糖∶n_阿拉伯糖∶n_木糖∶n_鼠李糖∶n_半乳糖=62.52∶23.05∶10.35∶2.78∶0.79∶0.51;BSP由两个主峰组成,相对分子质量分别为91.11、4.55 kDa。BSP是一种混合酸性多糖。     

Do environmental regulations hamper small enterprises' market entry? Evidence from China

Due to the serious increase of environmental pollution in China, environmental regulations have become significantly stringent. Such regulations are playing an increasingly important role in the development of small enterprises (SEs) in China, especially in SEs' market entry. However, existing studies pay little attention to this issue. This paper investigates for the first time the effect of environmental regulations on SEs' market entry and the mechanism of environmental regulation effects in China. We consider two sets of panel data for the periods 2003–2010 and 2012–2015 in China. We also use the fixed effect model and the instrumental variable method to explore the role of environmental regulations in SEs' market entry. The results show that, overall, environmental regulations play a significantly positive and robust role in SEs' market entry. However, the mechanisms associated with the effect of environmental regulations on different innovative types of SEs differ. Environmental regulations promote the market entry of SEs with product innovation, but this impact is not significant for SEs with research and development (R&D) activities and R&D institutions. Our findings indicate that China's SEs prefer product innovation, which is a lower level innovative type, over R&D innovation, as a means to avoid the negative impact of stringent environmental regulations.     

The effects of COVID-19 containment measures on the Asia-Pacific region

As the COVID-19 pandemic spread across the world, governments introduced significant containment measures to control the spread of the virus. In this paper, we leverage inputs from IMF desk economists to construct a novel narrative index of containment measures for 11 countries in the Asia-Pacific region. A key innovation in our index is that it distinguishes between economic sectors (services, industry, retail), thus providing a more granular view of restrictions related to economic activity. Using this index, along with other high-frequency data, we find that containment measures have been successful in reducing the spread of the virus (though with some heterogeneity) but have also been associated with large short-term economic costs. Furthermore, exploiting the granularity of our index, we find that differences in strategies across countries regarding the closing of the industrial sector have mattered: imposing less severe restrictions on industry has been associated with lower economic costs without leading to worse health outcomes, possibly reflecting the less contact intensive nature of industrial activity.     

Rewriting China’s Recent History: Fluctuations in State Economic Control, 1949–1984

China's political and economic systems are often discussed in combination. It is generally believed that under the political system of centralization, the economic system had to be a state monopoly. This article challenges that view by providing an economic perspective. The period 1949–1984 is selected to explore the causes of successive periods of strengthening and weakening of the state's monopoly power over the economy. Scholars have generally assumed that the period of state monopoly originated from socialist ideology or the personal will of the leaders. But economic conditions severely limited the options available. After the new China was established, the Chinese Communist Party (CCP) did not try to create a fully socialist economy in the short run. Instead, the CCP formulated a New Democracy platform that pragmatically allowed many types of enterprise to function side by side, including private industry, household ventures, and state‐owned enterprises. The original plan of the CCP was to allow private enterprise to develop in order to build up capital to rebuild the war‐damaged economy so that a strong foundation could be established for creating a socialist economy. But the Korean War from 1950 to 1953 and an influx of Soviet capital caused a shift from a mixed economy to state capitalism by 1956. From that point on, Mao Zedong and other Chinese leaders had to change course again and again as fiscal crises limited available options. A reversal occurred in 1958 when the Soviets withdrew both their advisors and their capital subsidies, leaving the state capitalist system weakened. The crisis in the Chinese economy from 1959 to 1961 required decentralization of economic authority and efforts to promote rural capital formation. The next shift occurred after 1963 as the economy was organized to prepare for a possible military invasion. The required mobilization of industrial resources in remote regions of China inevitably reinforced state management of the economy. The final reversal occurred in the late 1970s, when imports of Western technology and equipment created another fiscal crisis for the central government, which then had to shift the burden of capital formation from the state to private entities. The reform of the rural household contract system, the adjustment of economic structures, and an increase in exports to gain foreign exchange all took place as part of “de‐monopolization” reforms. The reforms that occurred after 1979 were not an aberration or a radical break from the past. They were part of a pattern that evolved from 1949 to 1984, with fluctuations dependent on the weakening and strengthening status of state finances. The shifts that occurred during this period have either been ignored by observers, or they have been misinterpreted as being motivated by ideology. In fact, new policies were created to enable the government to adjust to changes in the internal and external environment.     

Covariance breakdowns and connectedness of crude oil futures markets with non-synchronous data

ABSTRACT

This article identifies the breakdowns in the covariance of three benchmark crude oil futures markets (WTI, Brent and Dubai) and investigates the changes of market connectedness across the breakdown periods. As the crude oil futures are traded in different regions, this article eliminates the non-synchronous trading data by employing the Vector Moving Average structure and the Bayesian data augmentation approach, which keeps the integrity of original data without changing its properties. The results show that there are significant breaks in the covariance structure of crude oil futures markets. The breakdown periods are consistent with the periods when the market volatilities are at high level and the returns are volatile. The changes of market connectedness are independent of the covariance states, which supports the globalization hypothesis for the crude oil market. The results also suggest that there is more information flow out of the WTI than to the WTI during the sample period, particularly during the breakdown periods in 2008–2009.     

乡村振兴背景下乡村旅游环境正义实现途径

［目的］为改变乡村旅游非生态化发展的现状，全面实现乡村振兴。［方法］结合使用文献综述法和实地调研法，基于环境正义理论，将环境问题与社会正义结合起来分析乡村旅游环境问题产生的根源。［结果］一直以来，乡村旅游作为实现乡村振兴的重要方式都过于追求经济效益，而忽视了给乡村旅游地及其周边区域带来的环境污染和生态破坏，造成乡村旅游种际环境非正义和人际环境非正义。［结论］代内人际环境正义的实现是解决乡村旅游环境问题的关键，确保未来乡村旅游发展的环境正义导向和矫正当前存在的环境非正义是必须同时兼顾的两个方面。实现乡村旅游环境正义，一方面应增强主体的环境正义意识、构建公正的环境相关制度以确保乡村旅游未来发展的环境公正导向，另一方面应探索建立乡村旅游生态补偿制度对已经造成或现阶段无法避免的环境非正义结果进行矫正，实现补偿正义。     

An inexact l2-norm penalty method for cardinality constrained portfolio optimization

Abstract

We analyze and solve a single-period portfolio optimization problem with non-convex constraints, which address practical concerns of investment such as the active share weights of sectors and the number of stocks held in a portfolio. We reformulate the problem to simplify the computation and propose an inexact l₂-norm penalty method to solve the problem.     

Volatility of volatility is (also) rough

Using high-frequency data for major volatility indexes, we compute the volatility of volatility and show that its logarithm follows a fractional Brownian motion with Hurst parameter smaller than 1/2 thereby extending to the volatility asset class the recent findings obtained for the equity index markets. The results confirm that the volatility of volatility is a rough process and it possesses the long memory property. We also show that the correlation between the volatility and the volatility of volatility is positive, consistent with observations in the volatility option market. Lastly, a robustness check using volatility futures confirms the findings.     

多创新方法集成与融合应用的LCUE矩阵法研究及实施

在日益复杂的产品需求和生产环境下，企业面临的生产难题也更加复杂，如何科学系统地使用创新方法解决企业生产难题，是长期困扰企业的问题。研究多个创新方法集成与融合应用概念模型，构建以企业生产难题为导向的多创新方法集成与融合应用理论体系，并基于多创新方法集成与融合应用过程，提出从多个维度指导企业实施多创新方法集成与融合应用的“LCUE矩阵法”。最后，结合某空调装配企业生产实际，以价值流方法为模板，基于LCUE矩阵实施多创新方法集成与融合应用，有效解决了企业生产难题，验证了多创新方法集成与融合应用及LCUE矩阵法的可行性。