The analysis of incomplete data using stochastic covariates

In the development of many diseases there are often associated random variables which continuously reflect the progress of a subject towards the final expression of the disease (failure). At any given time these processes, which we call stochastic covariates, may provide information about the current hazard and the remaining time to failure. Likewise, in situations when the specific times of key prior events are not known, such as the time of onset of an occult tumour or the time of infection with HIV-1, it may be possible to identify a stochastic covariate which reveals, indirectly, when the event of interest occurred. The analysis of carcinogenicity trials which involve occult tumours is usually based on the time of death or sacrifice and an indicator of tumour presence for each animal in the experiment. However, the size of an occult tumour observed at the endpoint represents data concerning tumour development which may convey additional information concerning both the tumour incidence rate and the rate of death to which tumour-bearing animals are subject. We develop a stochastic model for tumour growth and suggest different ways in which the effect of this growth on the hazard of failure might be modelled. Using a combined model for tumour growth and additive competing risks of death, we show that if this tumour size information is used, assumptions concerning tumour lethality, the context of observation or multiple sacrifice times are no longer necessary in order to estimate the tumour incidence rate. Parametric estimation based on the method of maximum likelihood is outlined and is applied to simulated data from the combined model. The results of this limited study confirm that use of the stochastic covariate tumour size results in more precise estimation of the incidence rate for occult tumours.     

近代留美学生与中美教育交流研究

近代留美学生既是中美教育交流的产物,也是学习与回报美国教育、有组织交流的主要动力与媒介。他们推动的交流在实践中虽有种种局限,但在双向、平等、立体的进行中仍不失灵活、深刻而日趋完整。     

意识形态视角下的美国对华政策

作为一种系统的认识论或道德信念模式,意识形态在各国的外交政策中事实上起着世界观和方法论的作用。美国虽然号称最讲究“实用主义”,但它的对外政策同样也一直深受其意识形态的影响,尤其明显地反映在它的对华政策中。意识形态依然是美国决定其对华政策的一个重要原因。     

AN ALGORITHM FOR THE CONSTRUCTION OF OPTIMAL OR NEAR-OPTIMAL CHANGE-OVER DESIGNS

This paper presents an algorithm for the construction of optimal or near optimal change-over designs for arbitrary numbers of treatments, periods and units. Previous research on optimality has been either theoretical or has resulted in limited tabulations of small optimal designs. The algorithm consists of a number of steps:first find an optimal direct treatment effects design, ignoring residual effects, and then optimise this class of designs with respect to residual effects. Poor designs are avoided by judicious application of the (M, S)-optimality criterion, and modifications of it, to appropriate matrices. The performance of the algorithm is illustrated by examples.     

21世纪的美国社会保障:趋势与借鉴

美国社会保障的未来趋势是：预期寿命延长、劳动力数量增长缓慢、退休人数增加、退休年龄不断提前，这些共同加剧了社会保障收支不平衡状况，企业成为社会保障的生力军，社会保障事业出现私有化和私营化苗头。其借鉴意义：重视预期寿命延长对社会保障的压力，及早为延长退休年龄做好准备工作，重新定位企业在社会保障制度中的地位，改善社会保障的管理工作。     

Stochastic Modelling of Times to Temperature for Furnaces Supplying Titanium Blooms to a Rolling Mill at TIMET

In conjunction with TIMET at Waunarlwydd (Swansea, UK) a model has been developed that will optimise the scheduling of various blooms to their eight furnaces so as to minimise the time taken to roll these blooms into the finished mill products. This production scheduling model requires reliable data on times taken for the various furnaces that heat the slabs and blooms to reach the temperatures required for rolling. These times to temperature are stochastic in nature and this paper identifies the distributional form for these times using the generalised F distribution as a modelling framework. The times to temperature were found to be similarly distributed over all furnaces. The identified distributional forms were incorporated into the scheduling model to optimise a particular campaign that was run at TIMET Swansea. Amongst other conclusion it was found that, compared to the actual campaign, the model produced a schedule that reduced the makespan by some 35%.     

赛珍珠与中国文化

赛珍珠从小就接触到中国传统的文化,并且在不知不觉中培养了对这种文化的热爱。基于对中国文化的认识,赛珍珠对中国文化的走向提出了富有个人特色的思考。作为一个作家,赛珍珠的创作不可避免地受到中国文化的影响,她对中国文化的热爱使她摆脱了西方中心主义的束缚,在描写中国的作品上取得了比20世纪其他西方作家更高的成就和声誉。     

Estimating ordered parameters by linear programming

There are many models that require the estimation of a set of ordered parameters. For example, multivariate analysis of variance often is formulated as testing for the equality of the parameters versus an ordered alternative. This problem, referred to as isotonic inference, constrained inference, or isotonic regression, has led to the development of general solutions, not often easy to apply in special models. In this expository paper, we study the special case of a separable convex quadratic programming problem for which the optimality conditions lead to a readily solved linear complementarity problem in the Lagrange multipliers, and subsequently to an equivalent linear programming problem, whose solution can be used to recover the solution of the original isotonic problem. The method can be applied to estimating ordered correlations, ordered binomial probabilities, ordered Poisson parameters, ordered exponential scale parameters, or ordered risk differences.     

美国能源教育发展及其启示

美国从1980年启动了“美国能源教育开发”项目,从不同层面开展对国民的能源教育,由此构建了覆盖全国的能源教育体系,找到了应对能源危机的教育途径,在提高国民的能源意识、增强国民的节能技术和节能自觉性,化解能源危机等方面取得了显著成就。美国能源教育开发的经验值得我们借鉴。     

中国加入八国集团研究

八国集团对世界事务的影响举足轻重,中国对于是否加入八国集团表现的顾虑重重。究其原因,一是担心八国集团会架空联合国;二是中国考虑到自己是一个发展中国家,而八国集团从本质上来说是一个富国俱乐部;三是八国集团曾经在1989年制裁过我们。但是,我们加入八国集团却有许多好处:一是可以更好的改善中美关系;二是可以吸引和争取更多的投资和贷款;三是可以从八国集团的内部影响八国集团的决策;四是符合我们的大国外交战略。相反,如果我们长期远离八国集团,就可能在将来被边缘化。在加入的方式上,中国可以先以观察员的身份列席八国首脑会议,等待合适时机,正式加入。