食品中钙含量的测定

文章采用重量滴定法对食品中的钙含量进行了测定,并将结果与容量滴定法进行相比,准确度高,操作简单便捷,回收率高,重现性好。     

Can domestication of wildlife lead to conservation? The economics of tiger farming in China

Tigers are a threatened species that might soon disappear in the wild. Not only are tigers threatened by deteriorating and declining habitat, but poachers continue to kill tigers for traditional medicine, decoration pieces and so on. Although international trade in tiger products has been banned since 1987 and domestic trade within China since 1993, tigers continue to be poached and Chinese entrepreneurs have established tiger farms in anticipation of their demise. While China desires to permit sale of tiger products from captive-bred tigers, this is opposed on the grounds that it likely encourages illegal killing. Instead, wildlife conservationists lobby for more spending on anti-poaching and trade-ban enforcement. In this study, a mathematical bioeconomic model is used to investigate the issue. Simulation results indicate that, unless range states are characterized by institutions (rule of law and low corruption) similar to those found in the richest countries, reliance on enforcement alone is insufficient to guarantee survival of wild tigers. Likewise, even though conservation payments could protect wild tigers, the inability to enforce contracts militates against this. Our model indicates that wild tigers can be protected by permitting sale of products from tiger farms, although this likely requires the granting of an exclusive license to sellers. Finally, it is possible to tradeoff enforcement effort and sale of products from captive-bred animals, but such tradeoffs are worsened by deteriorating tiger habitat.     

An integrated decision-support approach in prioritizing risks of non-indigenous species in the face of high uncertainty

When evaluating the risks of future invasions, we often have sparse information on the likelihood that a species will arrive, establish and spread in a new environment, and on the potential impacts should this occur. Conventional risk assessment, therefore, is limited in providing guidance in managing the risk of non-indigenous species (NIS). However, risk management decisions must be made facing these uncertainties to avoid high and irreversible impacts.We develop an integrated ecological economic modeling and deliberative multi-criteria evaluation (DMCE) approach to support group decision-making in risk prioritization, using an example of ten NIS that could potentially impact Australian plant industries. This innovative approach seeks to combine the advantages of dynamic modeling with the benefits of DMCE in assessing and communicating uncertainty. The model unveils the complexity of the socio-ecological system of biological invasion, with a scenario analysis designed to interactively communicate scientific uncertainty to decision-makers. The DMCE provides a structured approach to identifying stakeholders' key concerns in addressing economic, social, and environmental dimensions of NIS risk explicitly. Functioning as a platform for risk communication, the DMCE also offers an opportunity for diverse views to enter the decision-making process and for the negotiation of consensus consensuses.     

Optimal detection strategies for an established invasive pest

We model optimal detection of sub-populations of invasive species that establish ahead of an advancing front. For many invaders, eradication of the main population is an untenable goal, yet it may be possible to treat and eradicate emerging sub-populations once these sub-populations are detected. We embed a dynamically optimal post-detection management plan of sub-populations into a model of optimal detection effort determination and find that optimal detection effort depends, in part, on the distance from the main front: locations closer to the front with shorter management horizons enjoy lower reductions in overall cost from intervention. The uninfested landscape is divided into two zones, characterized by different dynamically optimal management plans: a suppression zone and an eradication zone. In the suppression zone, optimal detection effort increases with distance from the front. At the distance where the suppression zone yields to the eradication zone, optimal detection effort plateaus at its maximum level.     

The Asian clam Corbicula fluminea in the European freshwater-dependent industry: A latent threat or a friendly enemy?

While the biofouler Corbicula fluminea (Müller, 1774) is known to cause great economic losses in North America, studies reporting the problem in Europe are much scarcer. This paper explores the industrial effects of the species in Portugal, the gateway by which the bivalve entered Europe around 30 years ago. National waterworks, major power stations, cement plants, pulp and paper mills and irrigation systems were surveyed. The industrial impacts of the pest were shown to remain relatively mild; irrigation systems are those that seem to be facing more significant economic losses due to infestation. Possible reasons for the apparent discrepancy between this result and the species dispersal in natural ecosystems are discussed, and recommendations on adequate responses to the latent threat are provided. This study may assist the implementation of integrated pest management policies in countries at risk of invasion or recently invaded, and contribute to an understanding of the species’ progression in industrial environments.     

新型农村社会养老保险风险评估指标体系的设计与运用

新农保风险评估指标体系能够对新农保制度面临的风险大小进行评估,反映制度的可持续发展状况。从制度建立和运行程序上来看,新农保风险包括制度设计风险、筹资风险、基金投资风险、操作风险和给付风险。从这五个方面选取合适的指标可以建立起新农保风险评估指标体系,然后利用层次分析法可以确定出各指标的权重。新农保风险评估指标体系运用的关键是新农保风险评估标准的确定以及指标实际风险值大小的判定。     

上市公司信息披露质量直接测度理论模式研究

在理论上,人们对“如何评价上市公司信息披露质量”并没有达成统一认识;在实践中,各机构的研究也各具特色。直接测度方法是理论界和实践部门评价信息披露质量的主流方法,但是其完善进程缓慢,还存在忽视概念内涵的界定、评价指标体系差异大、对于是否设置评价指标权重的意见不一、观点的论证缺乏坚实的理论基础等问题。评价指标争议,可通过依据测量理论的概念化和操作化程序的实施来解决;而指标权重的确定,可在综合评价理论的指导下比较各方案的优缺点,以评价目标为导向,择优选用。应依据测量理论与综合评价理论分析和确定信息披露质量的评价维度与指标,并重视上市公司信息披露质量评价的市场反应。     

松毛虫危害的生态经济损失内容及评估指标体系构建探析

在查阅现有相关文献的基础上,结合松毛虫危害发生的实际情况,首先对松毛虫危害所引发的生态与经济损失的主要内容进行了系统地分析和论证,包括林产品、景观价值、农业、畜牧业、渔业、人类健康、涵养水源、保持水土、防风固沙、净化空气、调节气候、固碳制氧、生物多样性保护等11个方面的损失;接着构建了松毛虫危害的生态经济损失评估指标体系,其中共包括2个一级指标、4个二级指标、13个三级指标和26个四级指标。     

Foot‐and‐mouth disease and the Mexican cattle industry

The objective of this article is to analyze the domestic and international effects of a hypothetical foot‐and‐mouth disease (FMD) outbreak in the Mexican cattle industry. A discrete time dynamic optimization model of the Mexican cattle sector is specified, and linked to domestic and international markets. Economic consequences of FMD outbreaks are simulated over time and under different scenarios. Specific findings and general policy recommendations are provided. The study reports a range of outbreaks from localized to large scale and suggests that changes in economic surplus due to FMD range from a positive net gain of $0.89 to $1.6 billion to a net loss of about $67 billion, depending on the specific mitigation strategy and outbreak scenario.     

区域土地资源安全评价研究——以广东省四会市为例

针对目前土地资源安全评价研究中的不足,构建了区域土地资源安全评价指标体系框架,重点分析各指标的含义、指标值获取方法和评价标准,探讨了区域土地资源安全评价方法,并以广东省四会市为例进行评价指标体系及方法的验证.