乌桕的植物文化与经济价值

乌桕(Sapium sebiferum)是最早被我国先民所熟识和利用的经济树种之一,历代典籍中以乌桕为题的诗文屡见不鲜。探讨了乌桕的名称来源及种植历史,梳理了历代有关乌桕的诗文,总结了其代表的植物文化,简述了近现代关于乌桕的活性成分分析和综合利用研究进展。     

图解在英语语法教学中的应用

例证说明，图解法在英语教学中有奇妙的作用．英语教学中应用图解法、括号图解和树形图解讲解简单句、复合句、助动词和名词等可以使学生对英语语法结构及其规律有一个直觉认识。     

On the evaluation of steck's determinant for rectangle probabilities of uniform order statistics

An expeditious method is developed for systematically evaluating Steck’s determinant for rectangle probabilities of uniform order statistics as polynomials generated by a binary tree.     

An Extended Mixture Distribution Survival Tree for Patient Pathway Prognostication

Mixture distribution survival trees are constructed by approximating different nodes in the tree by distinct types of mixture distributions to improve within node homogeneity. Previously, we proposed a mixture distribution survival tree-based method for determining clinically meaningful patient groups from a given dataset of patients’ length of stay. This article extends this approach to examine the interrelationship between length of stay in hospital, outcome measures, and other covariates. We describe an application of this approach to patient pathway and examine the relationship between length of stay in hospital and/or treatment outcome using five-years’ retrospective data of stroke patients.     

TREE-BASED REGRESSION FOR A CIRCULAR RESPONSE

ABSTRACT

The application of conventional statistical methods to directional data generally produces erroneous results. Various regression models for a circular response have been presented in the literature, however these are unsatisfactory either in the limited relationships that can be modeled, or the limitations on the number or type of covariates admissible. One difficulty with circular regression is devising a meaningful regression function. This problem is exacerbated when trying to incorporate both linear and circular variables as covariates. Due to these complexities, circular regression is ripe for exploration via tree-based methods, in which a formal regression function is not needed, but where insight into the general structure and relationship between predictors and the response may be obtained. A basic framework for regression trees, predicting a circular response from a combination of circular and linear predictors, will be presented.     

Distance-Based Measures of Association with Applications in Relating Hyperspectral Images

We propose a distance-based method to relate two data sets. We define and study some measures of multivariate association based on distances between observations. The proposed approach can be used to deal with general data sets (e.g., observations on continuous, categorical or mixed variables). An application, using Hellinger distance, provides the relationships between two regions of hyperspectral images.     

论陕北汉画像圣树符号的宇宙论意义

作为汉代思想的物质载体,刻有圣树符号的陕北汉画像石造型多呈竖立型,反映了宇宙划分为天堂与人间,圣树为连接天堂与人间的唯一通道这样一种二分的垂直宇宙论。圣树图像并非为汉陕北汉画像石所独有,它普遍存在于世界各地的神话与仪式中,其原型为史前时代的宇宙树。圣树符号的史前图像探源表明,陕北汉画像石中的圣树图像并不是汉代升仙与厚葬思想的产物,其构图范式源自史前口传时代大传统以圣树为中心的神话宇宙论。     

猕猴桃产业演化发展探析

猕猴桃是原产我国的古老果树资源，曾长期处于野生状态。20世纪初，猕猴桃被引入西方国家并驯化形成新兴产业，以其非凡的营养价值享誉世界。我国猕猴桃产业起步于20世纪70年代，发展壮大于20世纪90年代，但与西方发达国家差距仍很大，主要归因于中西方饮食习惯等方面的不同。今后要科学地利用我国丰富的果树资源，并借鉴西方发达国家的成功经验，进一步充分发挥我国的劳动力优势，加入WTO后的中国果树产业是可以超越西方国家的，也能够创造享誉世界的中国品牌。     

Sample size selection in clinical trials when population means are subject to a partial order: one-sided ordered alternatives

The statistical methodology under order restriction is very mathematical and complex. Thus, we provide a brief methodological background of order-restricted likelihood ratio tests for the normal theoretical case for the basic understanding of its applications, and relegate more technical details to the appendices. For data analysis, algorithms for computing the order-restricted estimates and computation of p-values are described. A two-step procedure is presented for obtaining the sample size in clinical trials when the minimum power, say 0.80 or 0.90 is specified, and the normal means satisfy an order restriction. Using this approach will result in reduction of 14-24% in the sample size required when one-sided ordered alternatives are used, as illustrated by several examples.     

A nonparametric Bayesian approach to copula estimation

We propose a novel Dirichlet-based Pólya tree (D-P tree) prior on the copula and based on the D-P tree prior, a nonparametric Bayesian inference procedure. Through theoretical analysis and simulations, we are able to show that the flexibility of the D-P tree prior ensures its consistency in copula estimation, thus able to detect more subtle and complex copula structures than earlier nonparametric Bayesian models, such as a Gaussian copula mixture. Furthermore, the continuity of the imposed D-P tree prior leads to a more favourable smoothing effect in copula estimation over classic frequentist methods, especially with small sets of observations. We also apply our method to the copula prediction between the S&P 500 index and the IBM stock prices during the 2007–08 financial crisis, finding that D-P tree-based methods enjoy strong robustness and flexibility over classic methods under such irregular market behaviours.