2010年欧盟RASFF通报中国食品接触金属制品安全问题分析

根据2010年度欧盟食品和饲料快速预警系统（RASFF）向公众通报进口中国食品及饲料的安全问题的情况,本文针对其中的食品接触金属制品,总结通报国家的分布、产品涉及的风险因素,并分析问题产生的原因,探讨应对的措施,充分发挥风险预警作用,从而减少或避免类似情况发生。     

城市扩张与集约农业背景下浅层地下水重金属污染特征空间分析

地下水是城乡结合部和农村地区的重要饮用水源之一,城市的扩张和农业集约经营对地下水的影响日益明显。本文以典型区—沈阳沈北新区为例,以地下水重金属为评价指标,采用经典统计和地统计的方法,分析城乡交错地区地下水污染程度和空间分异性特征,旨在为类似地区土地利用规划和地下水环境管理提供科学依据。结果显示:Fe、Mn超标率较高,分布范围较广;Cd、Hg分布集中,受城镇化的影响较为明显;Pb与集中养殖产业分布关系密切;As的分布与当地化工企业有关;Fe、Mn空间变异性强,空间异质性主要受自然条件等结构性因素控制;Cd、Pb、Hg空间变异性中等,As空间变异性弱,Cd、Pb、Hg、As这四种元素空间异质性的形成主要受人为活动等随机因素的影响;初步发现Fe和Mn,Mn和As有相似的来源。     

Growth Optimal Investment Strategy: The Impact of Reallocation Frequency and Heavy Tails

The strategy to maximize the long‐term growth rate of final wealth (maximum expected log strategy, maximum geometric mean strategy, Kelly criterion) is based on probability theoretic underpinnings and has asymptotic optimality properties. This article reviews the allocation of wealth in a two‐asset economy with one risky asset and a risk‐free asset. It is also shown that the optimal fraction to be invested in the risky asset (i) depends on the length of the basic return period and (ii) is lower for heavy‐tailed log returns than for light‐tailed log returns.     

Distribution of parallel exchange rates in African countries

This paper investigates the distribution of parallel exchange rates in African countries using exploratory data analysis techniques and model fitting. Stable laws are fitted to empirical distributions using the maximum likelihood estimation method. Empirical evidence supports the stable hypothesis these distributions are positively skewed and have tails that are much heavier than Gaussian counterparts. The stable hypothesis is further supported by the “converging variance test,” which suggests that these distributions have infinite variance.     

Cross-ownership as a structural explanation for over- and underestimation of default probability

Based on the work of Suzuki, we consider a generalization of Merton’s asset valuation approach in which two firms are linked by cross-ownership of equity and liabilities. Suzuki’s results then provide no arbitrage prices of firm values, which are derivatives of exogenous asset values. In contrast to the Merton model, the assumption of lognormally distributed assets does not result in lognormally distributed firm values, which also affects the corresponding probabilities of default. In a simulation study we see that, depending on the type of cross-ownership, the lognormal model can lead to both over- and underestimation of the actual probability of default of a firm under cross-ownership. In the limit, i.e. if the levels of cross-ownership tend to their maximum possible value, these findings can be shown theoretically as well. Furthermore, we consider the default probability of a firm in general, i.e. without a distributional assumption, and show that the lognormal model is often able to yield only a limited range of probabilities of default, while the actual probabilities may take any value between 0 and 1.     

南充市米粉中重金属污染物调查与分析

为调查南充市米粉中重金属污染物情况,评价食用米粉摄入重金属对消费者的健康危害,采集南充市辖区不同类型、不同来源米粉样品200个,采用国家标准方法对米粉中5种重金属进行检测。结果表明:米粉中铅超标率为1.00%,镉超标率为0.5%,铬超标率为2.00%,砷、汞未超标,米粉中重金属综合污染指数为0.380,污染程度为安全,米粉综合健康危害指数为0.562,南充市米粉中重金属总体处于安全范围,不会对食用者造成健康危害。     

Is television advertising being placed to reach product users?

Several textbooks, journal articles, and advertising practitioners indicate that the advertising for many products should be directed toward the heavy users of the product category. Other works suggest that advertising should be directed at current users of a brand to retain them or to users of competitive brands in an effort to attract them. The purpose of this article is to compare these directions for how advertising should be placed with data showing how advertising is being placed. The comparison is made using supermarket scanner panel data and household advertising exposure data. Examples are also provided to indicate the extent to which advertising could be targeted to heavy users of the product category and users of a brand, given the actual viewing and consumption patterns. Several implications for the placement of advertising are discussed.     

环北部湾重化工港口经济发展策略

发展重化工港口经济是环北部湾经济建设的重要组成部分。文章从地理位置、港口资源、市场潜力、竞争压力、资金引进、项目审批以及面临机遇等方面,分析环北部湾发展重化工港口经济的条件,最后提出有关发展策略。     

Farmers’ attitude towards the policy of remediation during fallow in soil fertility declining and heavy metal polluted area of China

Numerous countries and regions face soil fertility decline and heavy metal pollution, and China implements a policy of remediation during fallow (PRF) to deal with such challenges. In this study, we examine the evolution of PRF and surveys of farmers’ attitudes in China. We present suggestions which can be used as reference for other countries and regions. The Chinese government implemented the policy of remediation during production (PRP) to control the heavy metal pollution of land in 2014. The effect was unsatisfactory due to the lack of cooperation amongst farmers. Therefore, the Chinese government implemented PRF in 2016. Our investigation of 247 farmers shows that farmers’ comprehensive assessment of PRF is positively influenced by the cognition of government implementation, the cognition of policy function and the evaluation of value perception, and the PRF still faces several problems, such as low cognitive level of policy function, incomplete regulations of supervision and poor supporting system. Hence, we suggest that government should educate and train farmers, improve the supervision and set up the supporting system of PRF.     

Statistical estimate of the proportional hazard premium of loss

The well known Proportional Hazard Premium Principle, introduced by Wang (1996), depends upon the survival function of the insured risk and a risk aversion index. Using this premium principle, we propose an asymptotically normal semi-parametric estimator for the net-premium of a high-excess loss layer of heavy-tailed claim amounts. An algorithm to compute confidence bounds is given. Moreover, a comparison between this estimator and the non-parametric estimator, proposed by Necir & Boukhetala (2004), is carried out.