Deriving reference values for nerve conduction studies from existing data using mixture model clustering

Objective: to obtain locally valid reference values (RVs) from existing nerve conduction study (NCS) data.Methods: we used age, sex, height and limb temperature-based mixture model clustering (MMC) to identify normal and abnormal measurements on NCS data from two university hospitals. We compared MMC-derived RVs to published data; examined the effect of using different variables; validated MMC-derived RVs using independent data from 26 healthy control subjects and investigated their clinical applicability for the diagnosis of polyneuropathy.Results: MMC-derived RVs were similar to published RVs. Clustering can be achieved using only sex and age as variables. MMC is likely to yield reliable results with fewer abnormal than normal measurements and when the total number of measurements is at least 300. Measurements from healthy controls fell within the 95% MMC-derived prediction interval in 97.4% of cases.Conclusions: MMC can be used to obtain RVs from existing data, providing a locally valid, accurate reflection of the (ab)normality of an NCS result.Significance: MMC can be used to generate locally valid RVs for any test for which sufficient data are available.¹     

Computer aided identification of eugonic gram-negative bacilli: Clustering for bacteriological screening

A system based on pattern recognition in terms of operationally meaningful criteria has been designed for the identification of eugonic gram-negative bacilli. It includes the selection of a battery of tests to be used as a screening. The results of these tests place each isolate in any one of a number of clusters. A second set of tests is used to identify the isolate as one of the species in the cluster. The system can identify most common species economically and can be used in clinical laboratories not equipped with computers.     

一个基于内容检索的医学图像数据库

介绍了一个基于图像内容检索的医学图像数据库系统。分别讨论了用于图像内容检索的颜色、纹理和形状特征以及在此特征集下的图像相似性度量 ;介绍了数据库的组织及该系统的界面     

To which chemical mixtures is the French population exposed? Mixture identification from the second French Total Diet Study

Through their diet, humans are exposed to a wide range of substances with possible adverse effects. Total diet studies (TDS) assess exposure and risk for many single substances or mixtures from the same chemical family.This research aims to identify from 440 substances in the second French TDS, the major mixtures to which the French population is exposed and their associated diet. Firstly, substances with a contamination value over the detection limit were selected. Secondly, consumption systems comprising major consumed foods were identified using non-negative matrix factorisation and combined with concentration levels to form the main mixture. Thirdly, individuals were clustered to identify “diet clusters” with similar consumption patterns and co-exposure profiles.Six main consumption systems and their associated mixtures were identified. For example, a mixture of ten pesticides, six trace elements and bisphenol A was identified. Exposure to this mixture is related to fruit and vegetables consumed by a diet cluster comprising 62% of women with a mean age of 51 years. Six other clusters are described with their associated diets and mixtures. Cluster co-exposures were compared to the whole population.This work helps prioritise mixtures for which it is crucial to investigate possible toxicological effects.     

集束化减压护理技术在糖尿病足神经性溃疡的应用研究

目的：探讨集束化减压护理技术在糖尿病足神经性溃疡愈合中的作用。方法：选取上海市某三级甲等医院糖尿病足专科门诊就诊的老年糖尿病神经性溃疡患者49例,应用集束化减压护理技术,评价其康复效果。对患者的性别、年龄、病程、是否首次发病、复发溃疡次数、Wagner分级、日常生活能力（ADL）、就诊时行走状态、畸形情况、溃疡部位以及愈合时间进行调查。结果：49例神经性溃疡愈合时间为44.86±15.44天,其中有19例为复发性溃疡,占38.77%;患者ADL水平与就诊时行走状态对溃疡愈合时间有影响,差异具有统计学意义（P＜0.05）。结论：神经性足溃疡具有高复发率,应给予全程管理和专业支持。集束化减压护理技术对神经性足溃疡愈合起到关键作用,应用过程中需要关注患者自理能力及行走状态,给予专业和家庭支持,促进愈合,预防足溃疡的复发。     

基于关联规则与熵聚类的清热类中成药组方规律研究

目的:探讨常用清热类中成药组方规律。方法:收录《新编国家中成药》中清热类中成药处方,采用关联规则Apriori算法和复杂系统熵聚类等方法,确定处方中药物的使用频次及药物之间的关联规则等。结果:高频次药物包括甘草、黄芩、冰片、金银花、大黄、连翘等;高频次药物组合包括"甘草、黄芩""甘草、桔梗""连翘、金银花"等;置信度较高的关联规则包括"牛黄->冰片""桔梗->甘草""朱砂->冰片""栀子->黄芩"等。结论:处方用药中除常见的清热类中药外,尚包括具有清热作用的部分开窍药、安神药、泻下药及其他类药物。     

基于SPSS的共现聚类分析参数选择的实例研究

以OHSUMED语料库内提供的明确相关提问对为金标准和研究材料,借助BICOMB软件生成主题词-来源文献矩阵和共词矩阵,并获得各种系数的相似（相异）矩阵,对比分析目前国内基于SPSS共现聚类分析过程中主题词-来源文献矩阵与共现矩阵、各种相似性参数和各种类间距离计算方法的聚类效果。结果表明：主题词-来源文献矩阵聚类结果优于共词矩阵,在聚类分析中应优先选择。共词矩阵选择相似系数时应结合实际矩阵数据性质,并注意聚类方法原理上的正确性。     

Improving cluster visualization in self-organizing maps: application in gene expression data analysis

Cluster analysis is one of the crucial steps in gene expression pattern (GEP) analysis. It leads to the discovery or identification of temporal patterns and coexpressed genes. GEP analysis involves highly dimensional multivariate data which demand appropriate tools. A good alternative for grouping many multidimensional objects is self-organizing maps (SOM), an unsupervised neural network algorithm able to find relationships among data. SOM groups and maps them topologically. However, it may be difficult to identify clusters with the usual visualization tools for SOM. We propose a simple algorithm to identify and visualize clusters in SOM (the RP-Q method). The RP is a new node-adaptive attribute that moves in a two dimensional virtual space imitating the movement of the codebooks vectors of the SOM net into the input space. The Q statistic evaluates the SOM structure providing an estimation of the number of clusters underlying the data set. The SOM-RP-Q algorithm permits the visualization of clusters in the SOM and their node patterns. The algorithm was evaluated in several simulated and real GEP data sets. Results show that the proposed algorithm successfully displays the underlying cluster structure directly from the SOM and is robust to different net sizes.     

北京市城乡结合部中老年人心血管疾病危险因素及聚集情况分析

目的分析北京市城乡结合部中老年人心血管疾病危险因素及其聚集情况。方法 2007年采用多阶段整群随机抽样方法对16371名35～74岁北京市城乡结合部居民进行横断面调查,通过问卷调查、体格检查和实验室检查收集资料进行分析。结果北京市城乡结合部中老年人超重或肥胖、糖尿病、高血压、血脂异常和吸烟等主要心血管疾病危险因素的患病率分别为36.2%,6.5%,36.9%,35.4%和36.3%。83.0%,47.2%和17.5%的中老年人分别具有≥1、≥2和≥3种心血管疾病危险因素聚集。男性≥1、≥2和≥3种心血管疾病危险因素聚集危险分别是女性的3.4、4.3和5.4倍。结论北京城乡结合部中老年人群主要心血管疾病危险因素及其聚集暴露率较高,有必要采取禁烟、健康饮食和增加体力活动等人群干预措施。     

云南玉龙雪山自然保护区小型兽类群落系统聚类分析与区系研究

1998年10月－1999年6月,对云南丽江玉龙雪山自然保护区五种森林植被带采用夹日法进行小型兽类的垂直分布调查,共获小兽5目8科17属27种,共1530只;中对各小兽群落结构、物种丰富度、物种多样性,均匀度和生态优势进行了测定和比较,认为群落稳定性最高是针阔叶混交林,而最低是农耕区。通过采用系统聚类和极点排序分析方法 对各植被带小兽类进行数值分类,明确了该山系两大动物区系的分界线和各垂直带小兽分布的区系范畴;研究认为,海线的温凉性针阔叶混交林小兽群落特征、区系特点进行了分析和讨论。