中国城市土地市场有效性的实证研究

将有效市场假说应用于我国城市土地市场中,利用全国土地交易价格指数,采用序列相关检验、游程检验和方差比检验3种方法分别对我国城市土地市场的弱式有效性进行了实证检验,一致得出我国城市土地市场尚未达到弱式有效的结论.提出了对策建议:①营造公平、公开、公正的土地市场环境,发挥市场在配置土地资源方面的基础性作用.②打破对一级土地市场的垄断,构建城乡一体化的土地市场.③构建完善的土地市场指数系统,强化信息基础平台建设.     

国家生态工业示范园对企业绿色创新的影响研究

国家生态工业示范园是中国工业绿色转型的主要载体。本文基于创建国家生态工业示范园为切入点,采用多期双重差分法（difference-in-differences, DID）和2002-2017年上市公司的面板数据,实证考察了国家生态工业示范园对企业绿色创新的影响。研究发现：①创建国家生态工业示范园显著促进了企业绿色创新,平均提升了上市公司绿色发明专利0.883项,绿色实用专利0.465项;②事件分析表明,国家生态工业示范园与企业绿色创新之间存在着“先增后降”的倒“U”形关系;③国家生态工业示范园显著增加了企业环保投资,抑制了企业排污费,但与政府环保补助之间没有必然联系;④国家生态工业示范园更有助于非国有企业、经营状况比较好的企业以及东部经济发达地区的企业绿色创新,并且其绿色创新效应不集中于特定行业（如重污染行业）。本文从微观企业层面为理解创建国家生态工业示范园的经济社会效益提供了启发。     

基于正态分布假设检验的湖泊营养盐浓度分级评价方法研究

目前湖泊营养盐浓度级别评价常采用的平均值法忽视了变量的不确定性.本文据此提出一种基于正态分布总体均值假设检验的级别评价方法,并结合我国地表水环境质量标准(GB3838—2002)对营养盐浓度的分类,提出了简便快捷的图示法.结果发现,该方法能体现营养盐浓度变量的不确定性,融合先验级别假设,将决策风险定量化,可提供较为广阔的决策空间.同时,采用该方法对滇池外海观音山监测断面氨氮浓度的水质级别进行评价,发现先验级别假设、样本容量和决策偏好对评价结果有显著影响;与平均值法的比较发现,假设检验法具有更小的错误概率(例如,样本容量13时,风险0.21),评价结果具有更高的可信度,验证了假设检验法的适用性.     

Heterogeneous effects of urbanization and environment Kuznets curve hypothesis in Africa

This work explores the heterogeneous effect of urbanization and nonrenewable energy consumption on the environment in 54 African nations. Panel data were used from 1996 to 2019. For estimation, panel quantile regression analysis, augmented mean group, panel threshold regression, and the environment Kuznets curve hypothesis were applied to check the relationship between income and carbon emissions. The study's outcome demonstrates that urbanization and nonrenewable energy consumption degrade the environment in Africa. Furthermore, an inverted U-shape relationship exists between economic growth and CO₂ emissions, confirming the environmental Kuznets curve hypothesis. The findings indicate that urbanization should be planned; otherwise, urbanization can cause environmental degradation. African countries must adopt green urbanization and use renewable energy and clean manufacturing technologies. The institutions are encouraged to execute the standard, regulatory environment, and policies to reduce carbon emissions. Countries throughout the African continent should actively respond to the issues by charting a separate and diverse route for urban development.     

Trophic Cascades Following the Disease‐Induced Decline of an Apex Predator,the Tasmanian Devil

As apex predators disappear worldwide, there is escalating evidence of their importance in maintaining the integrity and diversity of the ecosystems they inhabit. The largest extant marsupial carnivore, the Tasmanian devil (Sarcophilus harrisii) is threatened with extinction from a transmissible cancer, devil facial tumor disease (DFTD). The disease, first observed in 1996, has led to apparent population declines in excess of 95% in some areas and has spread to more than 80% of their range. We analyzed a long‐term Tasmania‐wide data set derived from wildlife spotlighting surveys to assess the effects of DFTD‐induced devil decline on populations of other mammals and to examine the relative strength of top–down and bottom–up control of mesopredators between 2 regions with different environmental conditions. Collection of the data began >10 years before DFTD was first observed. A decrease in devil populations was immediate across diseased regions following DFTD arrival, and there has been no indication of population recovery. Feral cats (Felis catus) increased in areas where the disease was present the longest, and feral cat occurrence was significantly and negatively associated with devils. The smallest mesopredator, the eastern quoll (Dasyurus viverrinus), declined rapidly following DFTD arrival. This result suggests the species was indirectly protected by devils through the suppression of larger predators. Rainfall deficiency was also a significant predictor of their decline. Environmental variables determined the relative importance of top–down control in the population regulation of mesopredators. In landscapes of low rainfall and relatively higher proportions of agriculture and human settlement, top–down forces were dampened and bottom–up forces had the most effect on mesopredators. For herbivore prey species, there was evidence of population differences after DFTD arrival, but undetected environmental factors had greater effects. The unique opportunity to assess population changes over extensive temporal and spatial scales following apex predator loss further demonstrated their role in structuring ecosystems and of productivity in determining the strength of top–down control. Cascadas Tróficas Después de la Declinación Inducida por Enfermedad de un Depredador Apical, el Demonio de Tasmania     

Effects of maternal nutrition on post-weaning growth in two North American rodents

The Trivers-Willard hypothesis of sex-biased maternal investment in response to fluctuations in resource availability has provided a theoretical foundation for research on maternal investment for more than two decades. Their hypothesis holds that mothers in poor condition as a result of poor resource availability should bias parental investment towards offspring with the highest probability of reproducing. In the polygynous mating system of mammals where males compete for breeding access to females, the hypothesis predicts investment favoring females. Although data from many systems have supported this hypothesis, other systems do not follow the predicted patterns and have resulted in various alternative hypotheses. The present research was designed to test whether differences in body condition of young reared by nutritionally stressed dams relative to young reared by unstressed dams were maintained into adulthood, one of the fundamental assumptions underlying the Trivers-Willard hypothesis. Post-weaning growth in eastern woodrats (Neotoma floridana) and northern grasshopper mice (Onychomys leucogaster) was examined relative to maternal nutritional plane. Individuals from undernourished dams were lighter than their unrestricted counterparts at weaning but no difference was evident by the time they had reached adult size. Failure to maintain body condition differences into adulthood violates one of the assumptions essential for application of the Trivers-Willard hypothesis of maternal investment patterns. Although the Trivers-Willard model proposed that natural selection favors differential investment in the sexes over the entire course of parental investment, evidence from this and other studies suggests that the Trivers-Willard hypothesis might not be appropriate to address maternal investment questions in postnatally malnourished dams, but instead should be restricted to systems concerned with prenatal maternal condition or resource availability. Received: 22 February 1995/Accepted after revision: 30 December 1995     

The bottlenose dolphin community of Doubtful Sound features a large proportion of long-lasting associations

More than 12 studies of different bottlenose dolphin populations, spanning from tropical to cold temperate waters, have shown that the species typically lives in societies in which relationships among individuals are predominantly fluid. In all cases dolphins lived in small groups characterised by fluid and dynamic interactions and some degree of dispersal from the natal group by both sexes. We describe a small, closed population of bottlenose dolphins living at the southern extreme of the species' range. Individuals live in large, mixed-sex groups in which no permanent emigration/immigration has been observed over the past 7 years. All members within the community are relatively closely associated (average half-weight index>0.4). Both male–male and female–female networks of preferred associates are present, as are long-lasting associations across sexes. The community structure is temporally stable, compared to other bottlenose dolphin populations, and constant companionship seems to be prevalent in the temporal association pattern. Such high degrees of stability are unprecedented in studies of bottlenose dolphins and may be related to the ecological constraints of Doubtful Sound. Fjords are low-productivity systems in which survival may easily require a greater level of co-operation, and hence group stability. These conditions are also present in other cetacean populations forming stable groups. We therefore hypothesise that ecological constraints are important factors shaping social interactions within cetacean societies.Communicated by D. Watts     

Judicious Use of Multiple Hypothesis Tests

Abstract:  When analyzing a table of statistical results, one must first decide whether adjustment of significance levels is appropriate. If the main goal is hypothesis generation or initial screening for potential conservation problems, then it may be appropriate to use the standard comparisonwise significance level to avoid Type II errors (not detecting real differences or trends). If the main goal is rigorous testing of a hypothesis, however, then an adjustment for multiple tests is needed. To control the familywise Type I error rate (the probability of rejecting at least one true null hypothesis), sequential modifications of the standard Bonferroni method, such as Holm's method, will provide more statistical power than the standard Bonferroni method. Additional power may be achieved through procedures that control the false discovery rate (FDR) (the expected proportion of false positives among tests found to be significant). Holm's sequential Bonferroni method and two FDR-controlling procedures were applied to the results of multiple-regression analyses of the relationship between habitat variables and the abundance of 25 species of forest birds in Japan, and the FDR-controlling procedures provided considerably greater statistical power.     

Investigating the environmental Kuznets Curve and the role of green energy: Emerging and developed markets

In this study, the validity of the Environmental Kuznets Curve (EKC) hypothesis and the effect of green energy sources to decrease CO₂ emissions are examined for emerging and developed markets from 1990 to 2011 using a pooled mean group (PMG) estimator. Empirical findings of this study suggest that the EKC hypothesis is not confirmed by emerging markets; meanwhile, it is strongly supported by developed markets. The long-run elasticity results of per capita data may also imply a divergence between emerging markets and developed markets regarding CO₂ emissions. On the other hand, the findings of this study indicate that renewable energy sources will play an important role in reducing CO₂ emissions for both panel groups in the long run.     

Women infected with parasite Toxoplasma have more sons

The boy-to-girl ratio at birth (secondary sex ratio) is around 0.51 in most populations. The sex ratio varies between societies and may be influenced by many factors, such as stress and immunosuppression, age, primiparity, the sex of the preceding siblings and the socioeconomic status of the parents. As parasite infection affects many immunological and physiological parameters of the host, we analyzed the effect of latent toxoplasmosis on sex ratios in humans. Clinical records of 1,803 infants born from 1996 to 2004 contained information regarding the mother’s age, concentration of anti-Toxoplasma antibodies, previous deliveries and abortions and the sex of the newborn. The results of our retrospective cohort study suggest that the presence of one of the most common parasites (with a worldwide prevalence from 20 to 80%), Toxoplasma gondii, can influence the secondary sex ratio in humans. Depending on the antibody concentration, the probability of the birth of a boy can increase up to a value of 0.72, C.I.₉₅ = (0.636, 0.805), which means that for every 260 boys born, 100 girls are born to women with the highest concentration of anti-Toxoplasma antibodies. The toxoplasmosis associated with immunosuppression or immunomodulation might be responsible for the enhanced survival of male embryos. In light of the high prevalence of latent toxoplasmosis in most countries, the impact of toxoplasmosis on the human population might be considerable.