黑土地保护性耕作发展的制约瓶颈和突破路径

保护性耕作是东北黑土地保护利用的有效途径,是落实"藏粮于地、藏粮于技"战略的重要抓手。新世纪以来,黑土地保护性耕作经历了从农机主导向农机农艺融合发展的历程,呈现出技术结构集成化、推广主体多元化、应用主体规模化的发展趋势。同时,在黑土地保护性耕作发展过程中,面临着来自于农户认知、技术结构、土地规模、推广体系、补偿机制等方面的现实障碍。因此,需要从提升农户认知水平、加强先进适用的技术研发与集成、推进农业生产经营方式创新、构建新型农技推广体系、加强政策引导与法制建设等方面营造黑土地保护性耕作的发展之路。     

Policies to support ethnic minority enterprise: the English experience

Using Global Entrepreneurship Monitor data for 29 countries this study investigates the (differential) impact of several factors on female and male entrepreneurship at the country level. These factors are derived from three streams of literature, including that on entrepreneurship in general, on female labour force participation and on female entrepreneurship. The paper deals with the methodological aspects of investigating (female) entrepreneurship by distinguishing between two measures of female entrepreneurship: the number of female entrepreneurs and the share of women in the total number of entrepreneurs. The first measure is used to investigate whether variables have an impact on entrepreneurship in general (influencing both the number of female and male entrepreneurs). The second measure is used to investigate whether factors have a differential relative impact on female and male entrepreneurship, i.e. whether they influence the diversity or gender composition of entrepreneurship. Findings indicate that – by and large – female and male entrepreneurial activity rates are influenced by the same factors and in the same direction. However, for some factors (e.g. unemployment, life satisfaction) we find a differential impact on female and male entrepreneurship. The present study also shows that the factors influencing the number of female entrepreneurs may be different from those influencing the share of female entrepreneurs. In this light it is important that governments are aware of what they want to accomplish (i.e. do they want to stimulate the number of female entrepreneurs or the gender composition of entrepreneurship) to be able to select appropriate policy measures.     

The Black Enterprise Magazine Ranking of Colleges for African Americans: A Structural Analysis

This paper assesses the Black Enterprise Magazine (BE) ranking of the “top 50 colleges for African Americans,” which it publishes biennially. Its principal objective is to evaluate the statistical consistency in the ranking over the distribution of institutions that compose it. The paper attempts to address two-related questions. Does the BE report provide an unbiased and consistent assessment of the educational value associated with the institutions included in their listing? Is the ranking method internally consistent? Two experiments were used to evaluate the consistency of the BE ranking. First, structural difference in the model used to rank the institutions in the upper and lower half of the distribution is tested. Second, structural difference in the model used to rank HBCU and non-HBCU institutions included in the BE listed ranking is tested. In both cases the null hypothesis of the same structure is rejected.     

虚拟仪器技术对知识创造的影响研究

仪器作为现代科学研究的核心组成部分,在很大程度上决定了科学知识的产出。虚拟仪器技术对知识创造产生了深远影响。“软件就是仪器”的理念使得传统仪器、测量观念以及仪器作为科技黑箱的内涵和功能发生了质的变化。虚拟仪器在集成大量编码知识的同时更多地集成了主体的隐性知识,虚拟仪器技术通过对主体知识体系的重塑影响了知识创造。主体只有通过长时间、复杂的学习和使用过程才能充分发挥虚拟仪器技术在知识创造中的优势,实现编码知识和隐性知识的共同增长。     

Women,Ecology and Economics,edited by Ellie Perkins

This paper finds that black women earn 7 percent less than similarly skilled white women because of their race. Even within the same occupational category, black women earn 3 percent less than similarly qualified white women. Black women receive lower pay primarily due to occupational segregation and because they are rewarded with lower earnings than white women for equivalent levels of education and other human capital characteristics.     

Dynamic volatility spillovers between industries in the US stock market: Evidence from the COVID-19 pandemic and Black Monday

We examine the volatility spillovers among various industries during the COVID-19 pandemic period. We measure volatility spillovers by defining the volatility of each sector in the S&P 500 index and implement a static and rolling-window analysis following the Diebold and Yilmaz (2012) approach. We find that the pandemic enhanced volatility spillovers, which reveals the financial contagion effects on the US stock market. Second, there were sudden, large changes in the dynamic volatility spillovers on Black Monday (March 9, 2020), much of it due to the energy sector shock. These findings have important implications for portfolio managers and policymakers.     

Economic impacts of the Black Sea Grain Initiative

In this research, we use econometric analysis to estimate the impacts of the Black Sea Grain Initiative on international wheat and corn prices. Using these results, we assess the economic value of the treaty to the global food system, as well as the regional distribution of the associated welfare savings. We find that the Russian Invasion created economic costs of approximately $116.05 billion in the global wheat and corn markets. In the international wheat market, the Black Sea Grain Initiative reduced prices by 7.9%, offsetting approximately $21.48 billion of these costs. The largest winners from the Initiative outside Ukraine are primarily in the developing world, particularly in the Middle East and North Africa. We do not observe any economically meaningful impacts of the Initiative in the international corn market.     

The impact of Saturday trading on stock returns: Evidence from the Tokyo stock exchange January 1976 to January 1989

This paper examines the impact of TSE Saturday trading on daily TOPIX returns and TSE trading volume over the January 1976 to January 1989 period. Saturday trading is shown to have no significant impact on mean stock returns for the other days of the week. However, a significant shift in the pattern of Monday and Tuesday TOPIX returns is documented in the post-August 1986 period. This shift does not appear to be related to Saturday trading. TSE Saturday trading is found to have a significant impact on the variance of stock returns on surrounding days. In addition, trading volume is significantly lower on trading days surrounding Saturday trading. These findings are relevant to the timing of portfolio adjustment decisions.