分支格局、组份分析与中值淘汰法

文章简明介绍了现代分支系统学的分支格局原理和组份分析方法，并应用于李朝銮(1990，表2)的中国白粉藤属14种植物数据的分支分析。得出13个可能的最简约的二歧分支图，图长41步。这些分支图与李(1990)图2：13的比较表明，中值淘汰法不如组份分析方法有效，而且中值淘汰法有表相学和(或)进化系统学的疑问。     

一种概率密度的中值滤波算法

提出了一种新的图象噪声消除算法,该方法可以快速有效地去除图象中的脉冲噪声,并保留图象的细节.该算法主要通过利用象素点的值在滤波窗口出现的概率密度信息,进行噪声的判定及滤波过程的介绍,对本算法进行了分析仿真,结果表明该算法去除噪声与保留细节的效果好,且运算速度较快.     

基于偏微分方程的常用图像去噪方法比较研究

图像去噪在图像处理中极其重要。本文就几种常用的图像去噪方法进行了详细的综述,阐述了各方法的理论原理以及其优缺点,同时也给出了其对同一副测试图像的去噪效果。     

低对比度图像增强与边缘提取

针对低对比度图像增强和边缘检测问题，提出基于小波变换并结合中值滤波增强和Sobel算子边缘检测的变换处理方法，能获得尽可能完整的图像特征。     

Dyslipidemia in pregnancy may contribute to increased risk of neural tube defects -a pilot study in north Indian population

Neural tube defects are congenital structural abnormalities of the brain and vertebral column resulting from improper or non-timely closure of the neural tube. Prevalence of neural tube defects is reported to be higher among women with diabetes mellitus and obesity. This study was designed to investigate the relation between the presence of dyslipidemia in antenatal patients and the risk of fetal neural tube defects. The present study was an observational, cross-sectional study involving 129 pregnant women in 16 to 18 weeks gestation period. Of these, 80 women had normal pregnancies and 49 were clinically high-risk cases for neural tube defects. Fasting blood samples were analyzed for blood sugar and lipid profile by enzymatic assay and alpha-fetoprotein levels using Enzyme Immunoassay. Alpha-fetoprotein (AFP) values were converted to Multiples of Median (MoM) appropriate for the gestational age. Based on AFP values, women were labeled as screen negative (AFP <2 MoM, n= 102) and screen positive (AFP > 2 MoM, n =27). Screen positive women were further evaluated by ultrasound and 21 women were found to carry a neural tube defects positive pregnancy. Statistical analysis was done on SPSS software. Body weight of the women showed a significant positive correlation with serum triglycerides, plasma sugar and AFP MoM values. A significant difference was observed in serum cholesterol levels (p= 0.038), triglycerides (p=0.001) and plasma sugar levels (p=0.002) between normal women and those with neural tube defects positive pregnancy. The Odds ratio for neural tube defects risk in dyslipidemic cases was 24.23 (CI 4.73 − 148.60) with a relative risk of 12.12. Dyslipidemia especially hypertriglyceridemia was found to be significantly associated with fetal neural tube defects.     

柯西中值定理的复合证法

本文从柯西中值定理证明的基本思想出发,给出了引入辅助函数的六种思考方法。     

Understanding Student Attempts to Find a Line of Fit

The least squares method of fitting a line is not one that naturally occurs to students. We present three tasks to understand student views on how lines may be fit.     

Where do you stand? Notions of the statistical ‘centre’

We present a simple problem that can help highlight the decision-theoretic properties of various centrality measures. We also illustrate how the ‘centrality’parameters of the classical distributions in statistics would have to be modified if we were constrained to fewer defining principles.     

中值定理与拉格朗日插值函数

利用罗尔中值定理给出了函数与其拉格朗日插值函数间的关系,得到中值定理的另外一种形式,并给出了它的应用.     

Statistics Poker: Reinforcing Basic Statistical Concepts

Learning basic statistical concepts does not need to be tedious or dry; it can be fun and interesting through cooperative learning in the small‐group activity of Statistics Poker. This article describes a teaching approach for reinforcing basic statistical concepts that can help students who have high anxiety and makes learning and reinforcing these concepts more interesting and fun.