地方文化景观意义探讨--对蛇山南楼文化的再认识

武昌蛇山南楼在其千年传承的历史中形成了深厚的人文底蕴，南楼文化是武汉地域文化的重要组成部分。但是目前南楼文化远远没有得到应有的开发，因此，有必要充分发掘其丰富的文化内涵，使其重展昔日风采，从而推动武汉地区旅游经济的发展。     

广西岩溶地区“神山”的生态经济效益探讨

神山是广西岩溶地区民族植物文化的重要组成部分。本文论述了“神山”在保护生物多样性、调节小气候、改善区域环境、控制土壤侵蚀等方面的作用以及它的经济效益，在此基础上，针对岩溶地区“神山”当前面临的形势，提出了保护“神山”，恢复岩溶地区植被的建议。     

Characterisation of extensive beef cattle systems: Disparities between opinions,practice and policy

Increasing pressure on extensive farming systems in marginal areas requires them to become more resilient and adaptable to extreme conditions brought about by climate change. Yet these rangeland areas must also be protected as refuges for biodiversity and as important carbon stores. Recent United Kingdom policy initiatives are encouraging the use of traditional or native breeds of livestock to preserve genetic diversity, due to their perceived adaption to harsh environments and their value for managing extensive habitats for conservation. It is not clear however, whether these benefits are based on scientific evidence or perhaps more on current opinion; nor whether farm system practices are likely to change in response to these initiatives. This study offers an approach that can support future empirical studies designed to better inform such policy decisions.A survey was carried out to provide insight into current opinions regarding the impacts of cattle on hill environments and the cattle breeds appropriate for hill environments, before more detailed farm interviews provided data for a characterisation of suckler beef farming systems in Scotland using a typological approach. Survey results indicated that the majority of respondents believed cattle have a positive effect on hill environments when carefully managed, yet there was wide diversity in opinion regarding the type of impacts and most suitable breeds. Interview results highlighted the diversity of management systems, decision making processes and cattle types present and indicated significant variation in farmers’ views regarding breed hardiness, suitability and reasons for their choice of breed. Three system groups: Traditionalists, Improvers and Production optimisers, were clearly defined by the typology, with significant variation observed in their management practices and views. This study suggests that hill beef farmers appear to not only adapt their production systems according to their current bio-physical and financial circumstances, but also from personal experience. Accumulation of this kind of evidence is long overdue and could provide support to the development of any future policies regarding cattle and hill environments.     

Multivariate Hill Estimators

We propose two classes of semi‐parametric estimators for the tail index of a regular varying elliptical random vector. The first one is based on the distance between a tail probability contour and the observations outside this contour. We denote it as the class of separating estimators. The second one is based on the norm of an arbitrary order. We denote it as the class of angular estimators. We show the asymptotic properties and the finite sample performances of both classes. We also illustrate the separating estimators with an empirical application to 21 worldwide financial market indexes.     

鲁奎山铁矿成因探讨

鲁奎山铁矿为分布于滇中地区中元古代早期昆阳裂谷中,位于康滇地轴南段,赋存于昆阳群大龙组的菱铁矿床。铁矿产于大龙口组底部条带状灰岩中,呈似层状分布,层控明显。该类型铁矿为目前已探明的昆阳群中最大的铁矿,占云南省内已探明铁矿的20%以上。本文通过对鲁奎山铁矿的区域构造、矿床地质、控矿因素的分析,确定矿床成因,为更好的开发利用此类铁矿提供基础。     

基于Hill估计的VaR计算——以次贷危机为例

对极值分布的尾部形式、Hill估计量、风险价值分析等进行了理论分析,应用极值理论中的Hill估计对2002-01-04至2008-09-18期间的上证综指、道琼斯指数、恒生指数等做了风险价值的计算,比较和分析各国面临的市场风险的大小：认为美国次贷危机的爆发给全球金融市场带来了巨大风险,对中国的影响尤为巨大。     

北京西山南大寨逆冲推覆构造的初步研究

南大寨逆冲推覆构造,为推土机式的双重逆冲构造。它的主干逆冲断系及其间断夹块,一起构成背形叠置双冲式;主逆冲岩席及断夹块叠在一起形成推覆体堆,如同一个推土机沿底冲断面向前位移,致使主断面下盘出现由一系列次级逆冲断层域交织而围限的透镜状断片域,类似于推土机前侧的堆积区,称为前积带。南大寨逆冲推覆构造的这种总体结构特征,可以与Boyer和Elliott所提出的理想冲断带模型相对比。     

Extreme observations and risk assessment in the equity markets of MENA region: Tail measures and Value-at-Risk

The standard “delta-normal” Value-at-Risk methodology requires that the underlying returns generating distribution for the security in question is normally distributed, with moments which can be estimated using historical data and are time-invariant. However, the stylized fact that returns are fat-tailed is likely to lead to under-prediction of both the size of extreme market movements and the frequency with which they occur. In this paper, we use the extreme value theory to analyze four emerging markets belonging to the MENA region (Egypt, Jordan, Morocco, and Turkey). We focus on the tails of the unconditional distribution of returns in each market and provide estimates of their tail index behavior. In the process, we find that the returns have significantly fatter tails than the normal distribution and therefore introduce the extreme value theory. We then estimate the maximum daily loss by computing the Value-at-Risk (VaR) in each market. Consistent with the results from other developing countries [see Gencay, R. and Selcuk, F., (2004). Extreme value theory and Value-at-Risk: relative performance in emerging markets. International Journal of Forecasting, 20, 287–303; Mendes, B., (2000). Computing robust risk measures in emerging equity markets using extreme value theory. Emerging Markets Quarterly, 4, 25–41; Silva, A. and Mendes, B., (2003). Value-at-Risk and extreme returns in Asian stock markets. International Journal of Business, 8, 17–40], generally, we find that the VaR estimates based on the tail index are higher than those based on a normal distribution for all markets, and therefore a proper risk assessment should not neglect the tail behavior in these markets, since that may lead to an improper evaluation of market risk. Our results should be useful to investors, bankers, and fund managers, whose success depends on the ability to forecast stock price movements in these markets and therefore build their portfolios based on these forecasts.     

Is the Risk Comparison Made by the Public Between EMF and Smoking or Asbestos a Valid One?

The possibility of adverse health effects from exposure to extremely low frequency (ELF) electric and magnetic fields (EMF) has caused considerable controversy in the scientific community and has received great attention in the media and among the general public with many comparing ELF EMF with tobacco smoking and asbestos. Although both smoking and asbestos are now classified by the International Agency for Research on Cancer (IARC) as Group 1 or “established” carcinogens, this was not always the case. In this paper the evidence for the carcinogenicity of ELF EMF is compared with that for smoking and asbestos using the Bradford Hill model for establishing causality between exposure and disease. Application of the model shows that present data are insufficient to demonstrate that exposure to ELF EMF poses a definite human health hazard. However, while the bulk of the evidence is weak, there are several epidemiological studies which have reported an association between prolonged exposure to magnetic fields at levels above what is normally encountered and an increased risk in childhood leukaemia. On this basis IARC has classified ELF magnetic fields as a Group 2B or “possible” carcinogen.