杨梅疏果量与经济效益关系分析

用比较分析法和多目标最优化法对不同的杨梅疏果量与投入、产量、产值、效益的关系进行比较、分析表明 :疏果措施可提高杨梅的品质 ,增加产值和收益 ,当疏果量达到 6 0 %时有最大的纯收益 ,疏果量达到 70 %时有最好的投资效果 ,6 0 %～ 70 %的疏果量是杨梅最佳疏果方案     

Application of real options theory to forestry investment analysis

This paper demonstrates the utility of the real options approach to forestry investment analysis. The main objectives are to discuss the real option theory and show how it can be adopted to model uncertainty and managerial flexibility in forest management and investment. Secondly, we show how to calculate the option values of selected options that may be available to managers of forest industry firms. The paper provides an empirical application, which compares a forestry investment using the static Faustmann model and the real options approach. Four management options are used for the real options approach: an option to delay reforestation, an option to expand the size of the wood processing plant, an option to abandon the processing plant if timber prices fall below a certain level or due to corporate take-over, and multiple options that evaluated all three options together. All options were evaluated using the binomial option-pricing model, where timber values are assumed to follow a multiplicative binomial process. The results show that the Faustmann analysis rejected the investments as unprofitable, while the option analysis showed that all three options were highly valuable if exercised. When real options are considered, the traditional Faustmann model for assessing the profitability of a forestry investment may fail to provide an adequate decision-making framework because it does not properly value management's ability to adjust to shocks in the economy, as well as risks and uncertainty.     

Determinants of equity-based entry mode choice in the forest sector: the case of China

The focus of foreign direct investment (FDI) in the global forest sector has shifted from developed to developing economies (currently accounting 73% of total) during the past two decades. China has been the main global driver with its annual FDI soaring from USD 130 million in 2002 to USD 550 million in 2010. In light of international economic and business theories, choice of foreign entry mode is considered the most critical issue in corporate expansion strategy, which, however, has not been empirically studied in the forest sector. To fill this gap, our paper focuses on modeling two equity-based entry mode choices (i.e. wholly owned subsidiary or joint ventures) of foreign investment projects in China based on data from 109 activities of the Top 100 forest, paper, and packaging industry companies. By using logistic modeling, the main determinants of corporate entry mode choice are found to be cultural and geographical distance between the corporate home country and China, duration of corporate presence in China, and spatial concentration of local-level forest industry. Instead, investment project size and local resource availability are found to have no significant impact on corporate entry mode choice in China.     

Latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (Sceloporus undulatus)

Geographic variation in life‐history traits among populations of wide‐ranging species is influenced by both spatial and temporal aspects of the environment. Rarely, however, are the effects of both aspects examined concurrently. We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi) and southern (Florida) populations, spanning nearly the full latitudinal range of the species, to examine amongpopulation differences in strategies of reproductive energy allocation. Adult females from the southern population were smaller, and produced fewer and smaller eggs in their first clutches than did females from the more northern populations. Southern females were more likely to produce a second clutch, and second clutches were smaller than first clutches for females from the 2 northern populations. Together these trends eliminated population differences in overall reproductive output after accounting for body size. The trend for greater reproductive energy to be allocated to first clutches at higher latitudes, and to later clutches at lower latitudes is corroborated by published data from field studies on multiple populations. Distributing reproductive effort by producing more clutches of smaller eggs may be an adaptive response to the long season available for egg incubation and lizard activity in sub‐tropical southern environments. In contrast, allocating greater resources to early reproduction may enhance maternal fitness in the relatively short activity seasons that characterize more northern sites.     

信阳高新技术产业开发区投资与经济增长关系研究

通过对信阳高新技术产业开发区投资和经济增长的关联度分析,指出投资是拉动信阳高新区经济增长的主要因素,经济增长会带来投资的迅速增加,两者存在着双向的因果关系,应使投资保持一定的增长速度,促进经济增长。     

农业科研单位科普旅游与休闲农业错位投入分析

试图从科普旅游和休闲农业的内涵特征入手,分析提出二者间的错位投入思路,旨在以较低的投入,获得促进二者间良性互动发展的实效.     

农村基础设施投资效益评价的关键指标遴选

农村基础设施对中国的农业增长、农村经济发展及脱贫意义重大。但中国目前尚没有完善相关设施的评价体系,尤其此类评价体系中的评价指标更是缺少。该研究旨在建立一套客观评价农村基础设施投资效益的关键指标体系（CAIs）。针对农村基础设施投资效益评价指标,通过对政府、高校和研究机构、咨询企业专家展开两轮问卷调查,进而采用蒙特卡罗模拟（MCS）分析问卷调查反馈的数据,并根据模拟结果运用模糊集合理论选取关键评价指标,总共选取了8个关键指标。研究表明,MCS可以有效克服数据源不足的缺陷,而模糊集合理论可以应对问卷调查中专家意见的模糊性。遴选出的8个关键指标与已有的零星研究相印证,为政府在农村基础设施投资提供依据。     

国内外农业科研投资经济效益实证研究的比较分析

对国内外农业科研投资水平及其投资回报率进行比较分析,得出如下结论：中国农业科研投资近年来增速较快,但农业科研投资强度仍很低;中国农业科研投资回报率一直保持较高的水平。中国农业科研投资的经济效益在研究方法和研究领域需要不断拓展与创新。     

From killer to carer: steroid hormones and paternal behaviour

Mammalian parental investment (i.e. care of descendant offspring) is largely biased towards maternal contributions due to the specific feeding needs of mammalian offspring; however, varying degrees of paternal investment have been reported in about 10% of all mammalian species. Within the order Carnivora, paternal contribution to rearing offspring is particularly high: an estimated 32% of all studied carnivore species exhibit direct paternal care. Despite the prominence of paternal investment in carnivores, the endocrine basis of this behaviour is not well understood. This review examines the current – highly constrained – state of knowledge about the endocrine basis of carnivore paternal investment. We attempt to link changes in androgen and glucocorticoid levels with variation in direct and indirect paternal care behaviour making specific predictions regarding the way forward. Well-studied species, such as bat-eared foxes (Otocyon megalotis), dwarf mongoose (Helogale parvula) and meerkats (Suricata suricatta), where social dynamics are relatively well understood, can act as ideal model systems through which we may further investigate the endocrine basis of paternal investment in carnivores.     

关于启动民间投资加快西部开发的思考

西部开发是一项世纪性的事关全局的战略决策 ,从西部地区经济落后的原因分析入手 ,阐明了民间投资在西部开发中的作用 ,并对西部地区引进民间资本的可行性进行了论证