Data skeletons: simultaneous estimation of multiple quantiles for massive streaming datasets with applications to density estimation

We consider the problem of density estimation when the data is in the form of a continuous stream with no fixed length. In this setting, implementations of the usual methods of density estimation such as kernel density estimation are problematic. We propose a method of density estimation for massive datasets that is based upon taking the derivative of a smooth curve that has been fit through a set of quantile estimates. To achieve this, a low-storage, single-pass, sequential method is proposed for simultaneous estimation of multiple quantiles for massive datasets that form the basis of this method of density estimation. For comparison, we also consider a sequential kernel density estimator. The proposed methods are shown through simulation study to perform well and to have several distinct advantages over existing methods.     

Generalized inferences on the common mean vector of several multivariate normal populations

The hypothesis testing and confidence region are considered for the common mean vector of several multivariate normal populations when the covariance matrices are unknown and possibly unequal. A generalized confidence region is derived using the concepts of generalized method based on the generalized p$p$-value. The generalized confidence region is illustrated with two numerical examples. The merits of the proposed method are numerically compared with those of existing methods with respect to their expected area or expected d-dimensional volumes and coverage probabilities under different scenarios.     

文化视野下的汉语民族性特点

汉语的民族性特点是在与其他民族语长期接触和融合过程中形成的.文章立足于中西文化和中华文化广阔视域,从语词类聚、句法组织、修辞方式、表达习惯等角度对汉语的民族性特点进行了全面描写,同时结合民族历史、政治制度、社会背景、价值观念、认知心理等诸因素,给予了发生学解释.     

几种传输线的场分布

求开放平板线、外正三角形內圆同轴线、外方內圆同轴线、外正六边形內圆同轴线的特性阻抗而建立的精确保角变换的基础上,本文进一步讨论了显式逆变换函数,从而求得了这几种传输线的场分布的闭合表达式。由于所用保角变换的精确性,所得的显式场分布在内导体和外导体的内接圆尺寸之比小于0.5in。基本上是准确的,在这个尺寸比稍大些时也可作为参考。这些场分布对于了解传输线的功率容量,计算衰减常数,考虑功率耦合,设计有关的有源器件等都是必不可少的。文中获得的几种传输线的场分布的显著特点是计算方便,在一般实用范围內有足够的精度。     

Topics in Microbial Risk Assessment: Dynamic Flow Tree Process

Microbial risk assessment is emerging as a new discipline in risk assessment. A systematic approach to microbial risk assessment is presented that employs data analysis for developing parsimonious models and accounts formally for the variability and uncertainty of model inputs using analysis of variance and Monte Carlo simulation. The purpose of the paper is to raise and examine issues in conducting microbial risk assessments. The enteric pathogen Escherichia coli O157:H7 was selected as an example for this study due to its significance to public health. The framework for our work is consistent with the risk assessment components described by the National Research Council in 1983 (hazard identification; exposure assessment; dose-response assessment; and risk characterization). Exposure assessment focuses on hamburgers, cooked a range of temperatures from rare to well done, the latter typical for fast food restaurants. Features of the model include predictive microbiology components that account for random stochastic growth and death of organisms in hamburger. For dose-response modeling, Shigella data from human feeding studies were used as a surrogate for E. coli O157:H7. Risks were calculated using a threshold model and an alternative nonthreshold model. The 95% probability intervals for risk of illness for product cooked to a given internal temperature spanned five orders of magnitude for these models. The existence of even a small threshold has a dramatic impact on the estimated risk.     

四川盆地西北部蕈菌资源

1986年以来在四川盆地西北部采集到205种草菌,其中包括省内新记录种60种,国内新记录种4种。根据G.C.Ainsworth等(1973)的分类系统分类并命名。所有标本保藏在四川锦阳农业专科学校真菌标本室。     

深圳十年规划建设理论与实践初探

本文根据深圳十年规划与建设经验,对市场经济条件下的城市规划理论、乡镇城市化、开放型城市的交通与电讯网络、城市生态环境的保护、投资软硬环境的建设,以及如何提高城市规划的科学水平等问题作了探讨。     

Reference priors for a product of normal means when variances are unknown

The reference priors of Berger and Bernardo (1992) are derived for normal populations with unknown variances when the product of means is of interest. The priors are also shown to be Tibshirani's (1989) matching priors.     

1998年狮子座流星暴的一些预测

1998年狮子座流星暴是本年度最重要的天象之一。而广东省处于观测的最有利位置,为了不错过这次十分难得的机会,本文叙述了狮子座流量暴的本质及其观测工作的意义,求出了该流星暴母体的部分轨道根数;对1998年狮子座流星暴作了一些预测;对观测方法提出了一些建议,本次预测虽用的是天文专业的方法,但为了使更多的观测员理解,本文尽可能使用最基础的知识。     

多方发挥物理实验教学的职能作用

当前我国医学教育中物理实验教学存在弱点:对物理教育不重视,实验条件差,仪器、设备陈旧,实验选项过时,实验课时少.针对存在的问题及现状,在现有的条件之内,我们提出了物理实验课的改进措施:认真做好实验准备,发挥教师的主导作用,督查学生亲自动手,利用现有仪器设备,不断改善实验条件,重视教学情况的反馈信息.