季节性冻土的分布与变化特征及对多样性农区农业生产的影响

[目的]研究季节性冻土的分布与变化对多样性农区农业生产的影响,对于合理利用气候资源,指导当地农业生产具有重要的意义。[方法]文章以临汾市为例,选用1960—2019年临汾市17个观测站逐日的冻土深度、温度、地温、降水量和蒸发量等资料数据,采用克里金空间插值法分析研究区冻土的空间分布,并运用M-K检验、一元线性回归、相关分析等方法分析研究区不同海拔高度季节性冻土的变化趋势及影响因素。[结果](1)临汾市季节性冻土深度山区大于盆地,北部大于南部,冻土深度与海拔高度正相关显著,相关系数为0.712 (P0.01)具有明显的垂直分布特征。(2)近年来最大冻土深度呈明显下降趋势,变化倾向率平均为-2.304cm/10年,高海拔地区变化趋势尤为显著,1982年冻土深度发生突变,突变后从一个相对偏深期跃变为相对较浅期。(3)冻土始冻日山区早于平川,北部早于南部,解冻日刚好相反,冻土持续期平均相差1个月左右;多年来临汾市土壤表面始冻日推迟,解冻日提前,冻土期明显减少,平均变化率分别为2.088d/10年、1.762d/10年和4.069d/10年,低海拔地区变化趋势更为明显。(4)相关分析表明,冻土深度受冬季地面最低气温影响极显著,其中1月的地面最低气温升高对冻土深度变化起到主要的促进作用,这种影响在高海拔地区更为明显;春、秋两季的地面最低气温升高,使研究区始冻日推迟,解冻日提前,相关系数分别为-0.741、-0.408 (P0.01),冻土期明显缩短,蒸发量的相对减少对冻土期和冻土深度变化起到一定抑制作用,降水量对冻土期和冻土深度影响甚微。[结论]临汾市冻土期缩短,冻土深度变浅,使越冬农作物干旱加剧,病虫害发生几率增加,同时增加了植物安全越冬系数,使作物生长季延长,对农业增产起到一定作用。     

The term structure of mutual fund herding

This paper investigates institutional herding behaviours in the U.S. Treasury market. We find that the level of herding is higher for bonds with a longer time to maturity and this pattern is significant only for buy herding, not sell herding. This term structure of herding is stronger for funds with a shorter investment horizon. These patterns remain strong for Treasury Inflation-Protected Securities and for Treasuries with high coupon rates. Overall, our findings support investors' short-termism as a channel for the term structure of herding and are inconsistent with other herding explanations, such as spurious herding, reputational concerns and information cascades.     

Pursuing opportunities in distance: the determinants of overseas R&D by Chinese multinationals

This study investigates two relevant dimensions of institutional distance – knowledge and economic distance – that influence the overseas research and development (R&D) intensity of emerging market multinational enterprises. We undertake a longitudinal analysis of 121 listed Chinese manufacturing multinational enterprises for the period 2011–2016. The results reveal that the enterprises' overseas R&D is more intense in host countries with greater knowledge and economic distance. Moreover, as the strength of intellectual property rights protection in host countries grows, the positive effects of knowledge and economic distance on the enterprises' overseas R&D intensity become weaker. We also find that political ties with home country governments strengthen the positive relationship between knowledge distance and the enterprises' overseas R&D intensity, while its moderating effect on the relationship between economic distance and overseas R&D intensity is insignificant.     

Unpredicted costly dividends and temporary short squeezes

We argue that cash dividend is a type of arbitraging cost that short sellers tend to avoid. We find that dividend announcements lead to temporary short squeezes, causing the prices of highly shorted stocks to overshoot and fully revert over time. These stocks also experience excessive buy-initiated trades and abnormal trading volume in response to dividend announcements. These results are driven mainly by stocks with unpredicted dividends, low lending fees, and high dividend yields. Overall, results suggest that news of a dividend distribution is magnified by short squeezes due to increased short costs and generates excessive nonfundamentals-driven price fluctuations.     

Disentangling the impact of temperature on consumers' attitudes toward nostalgic advertising

Although the effect of temperature on consumers is ubiquitous, little is known about how temperature affects consumers' attitudes toward nostalgic advertising. Drawing on embodied cognition theory, this study explores the effect of temperature on consumers' attitudes toward nostalgic advertising through the mediator of the affective system. Based on two experiments involving personal and historical nostalgic advertising, our results show that when exposed to comfortable temperature, consumers follow the “assimilative effect” of temperature; warm temperatures trigger more positive attitudes toward nostalgic advertising when compared with cool temperatures. However, when exposed to uncomfortable temperatures, consumers follow the “complementary effect” of temperatures; cold temperatures lead to more positive attitudes toward nostalgic advertising than hot temperatures. Furthermore, the affective system plays a mediating role between temperature and consumers' attitudes toward nostalgic advertising. This study contributes to the literature on temperature in marketing and provides a practical guide for companies to implement nostalgic advertising strategies.     

数字化转型与全要素生产率——基于A股上市公司的经验证据

数字化转型是把握时代方向赋能企业战略转型与变革的必然选择。在数字经济迭代更新的背景下，本文引入企业全要素生产率这一理论视角，选取2007—2020年A股上市公司数据，实证检验数字化转型对企业全要素生产率的影响效应。研究发现，第一，数字化转型显著提升企业全要素生产率水平，这一结论在选取历史数据作为工具变量及稳健性检验后仍然成立；第二，外部知识产权保护、组织内部冗余资源和管理者能力会强化数字化转型与企业全要素生产率之间的正向关系；进一步地，数字化转型对企业全要素生产率的激励效应得益于企业创新能力与企业专业化分工效率的提升，异质性分析表明在非国有和非高新技术企业样本中上述关系更加显著；最后，企业全要素生产率增长能够提升企业市场价值。本研究助推了全要素生产率动因以及数字经济赋能企业创新高质量发展的效应、机制和企业性质差异的理解，为更好的驱动企业数字化转型提供参考建议。