Cover's universal portfolio,stochastic portfolio theory,and the numéraire portfolio

Cover's celebrated theorem states that the long‐run yield of a properly chosen “universal” portfolio is almost as good as that of the best retrospectively chosen constant rebalanced portfolio. The “universality” refers to the fact that this result is model‐free, that is, not dependent on an underlying stochastic process. We extend Cover's theorem to the setting of stochastic portfolio theory: the market portfolio is taken as the numéraire, and the rebalancing rule need not be constant anymore but may depend on the current state of the stock market. By fixing a stochastic model of the stock market this model‐free result is complemented by a comparison with the numéraire portfolio. Roughly speaking, under appropriate assumptions the asymptotic growth rate coincides for the three approaches mentioned in the title of this paper. We present results in both discrete and continuous time.     

申遗背景下的中国自然遗产潜力评估

参照世界自然遗产地学、美学、生物生态过程和濒危物种栖息地4项申遗评选标准,依据地貌景观、生物景观等价值构成,建立美学价值评估方法;依据世界遗产13类地学主题评价框架、地质演化过程、典型类型地貌等价值构成,建立地学价值评估方法;依据生态系统过程、物种多样性、栖息地等价值构成,建立生物生态学价值评估方法。利用全球对比的方法提取和评估突出普遍价值,将中国自然遗产潜力区分为青藏高原区、西北干旱区、东部季风区等生态环境基本单元,筛选我国世界自然遗产潜力区。重点提出海洋类世界自然遗产和西部北部地区申遗的可能性,提出中国申报世界自然遗产突出普遍价值的评估策略与优先原则。     

全民健保战略目标下的医疗救助理念研究——浙江省新型社会救助体系的启示

在全民健保的战略目标下,医疗救助的地位被弱化,只是对因病致贫人员和特殊群体实行的临时性救助。然而,以缴费型保险为主的医疗保障体系不能从根本上解决贫困人口的医疗费用问题。因此,从目前过渡到全民健保阶段,医疗救助的地位不应该被削弱。目前我国医疗救助的理念定位不清,没有充分化解贫困人口的疾病风险。本文以全民健保的战略目标和医改为背景,对基本风险、最低需求、政府责任这几个基本概念加以界定;并从医疗救助化解的社会风险出发,分析全民健保战略目标下仍需医疗救助处理的基本风险;再以浙江省分层分类的覆盖城乡的新型社会救助体系为例,阐述医疗救助理念定位需要重点解决的两个关键问题,反思医疗救助与社会医疗保险的关系和医疗救助水平,促进公平和效率。     

我国社会保险费改税的争议与改革路径探讨

在我国,随着社会保障事业的推进,如何保障社会保险的资金来源成为迫切需要解决的一道难题。对此,学界和实务界关于社会保险是否应当费改税一直存有争议;而2010年10月出台的《社会保险法》采取了保守做法,依然沿用了通过缴费筹集社会保险基金的方式。然而,从长远计,社会保险费改税的制度变迁既有深厚的理论基础,也有坚实的现实需要。因此,应积极面对我国当前社会保险费改税的现实障碍,寻求各方利益的平衡和制度之间的协调,适时地、渐进地推动社会保险费改税,以全面缓解和克服目前因社会保障缴费体制不合理所带来的问题,更好地推动我国“普惠型”社会保障制度的建设。     

农民工医疗保障制度的路径选择探析

结合我国农民工特点和权利诉求、农民工医疗保障存在的难题,运用社会保障的基本理论,提出建立我国农民工医疗保障有效供给制度的路径选择,完善农民工特殊医疗保障项目和医疗救助体系;建立农民工医疗保障中间代理组织;加快农民工医疗保障与其他医疗保障制度的衔接,逐步向城乡居民统一提供公共卫生服务。     

Consistency and asymptotic normality of maximum likelyhood estimators

Abstract

Let the random variable X denote the time taken in completion of a process. For a fixed a, if the observed value of X is less than a, the X is observable, but if X is greater than a, the process is tampered with and is accelerated or decelerated at time a by some unknown factor α, and Y=a+α(X-a) is observed. If the experimenter has only partial control over the experiment, it may be difficult to get several observations on Y corresponding to the same a value. Thus we have a set of independent but not identically distributed observations. The large sample behavior of m.l.e. of the unknown parameters based on tampered random variables Y ^b1 , ..., Y ^bn is studied. If X follows an exponential distribution with mean (1/--), ... the consistency and asymptotic normality of the m.l.e. of α and -- is established under mild conditions on a ^b1, a ^b2, ... The conditions needed for establishing the consistency of m.l.e. of lX are given when X follows a uniform distribution U(O, --) or when X has any known distributional form     

One for all and all for one: privatization and Universal Service provision in the postal sector

Universal Service provision has a special role for the public utilities sector in many Organization for Economic Co-operation and Development (OECD) countries. These public utilities have largely been subject to privatization during the last 3 decades. Efficiency effects of privatization are widely documented while the impacts on the quality and accessibility of the Universal Service are not much examined. By using a unique dataset on privatization for 21 countries over the period 1980–2007 for the postal sector, we are able to show that privatization, in particular formal privatization, has led to a decrease in the quality of the Universal Service.     

基于帕累托改进理论视阙下的校企融合思考

目前,高职院校在与企业进行校企合作的过程中,越来越容易产生合作深度、合作边界难以把握的问题。双方在利益着眼点上的差异加剧了这一问题的严重性。为妥善处理这一困难,校企业合作的双方都有必要采用帕累托改进理论来达到交换、生产(教学)和产品混合最优,从而提高校企作的水平与质量。     

On the optimality and sustainability of Turkey’s current account

We analyze Turkey’s current account optimality and sustainability between 1992 and 2004. Using the intertemporal benchmark model for Turkey’s current account we test for its intertemporal solvency. Based on traditional and alternative tests (which account for persistence in the current account), we conclude that Turkey breached the intertemporal solvency condition in the sample period. In addition, stationarity tests of the deviation between actual and optimal net external liabilities series confirm that Turkey’s current account deficit was unsustainable for that period. However, further econometric investigation and analysis of reforms causes us to question our conclusions of non-optimality and unsustainability of the Turkish current account for the latter part of the period. We are indebted to two anonymous referees for insightful comments and suggestions. We would also like to thank seminar participants at Middle Eastern Technical University, Ankara, Turkey, for comments on an earlier version of this paper. Responsibility for all errors remains with the authors.     

翻译和谐性的CIN阐释

从认知角度看,翻译实质上是一个建立在多个认知主体(原作者,译者,读者)心理空间之上的心理互动过程。翻译要实现和谐性就必须处理好各认知主体间的互动关系。Fauconnier和Turner提出的CIN(概念整合网络)机制,能较好地解释翻译活动中作者、译者、读者之间的心理互动及整合运作过程。