不同条件下Percoll密度梯度离心分离组织细胞浮游生物的比较

目的实验评估不同条件下Percoll密度梯度离心分离组织中浮游生物的效果。方法大白兔肝组织匀浆后与3种藻类混合物混匀,分为混匀高速分离组、混匀低速分离组、叠加高速分离组、叠加低速分离组和未分离组(对照组)进行Percoll密度梯度离心分离浮游生物,镜检并提取其DNA,用PCR技术分别检测浮游生物16S rDNA和叶绿素基因特异性片段。结果混匀高速分离组有较多浮游生物呈分层条纹状分布于离心管中部,叠加高速分离组浮游生物紧邻组织细胞层下,低速分离组见较少浮游生物紧邻于组织细胞层之下,未分离组见浮游生物和组织细胞混杂沉于管底;经DNA检测,各分离组组织细胞层下液体均可检出浮游生物的1条447bp 16S rDNA片段及1条194bp叶绿体/叶绿素脱辅基蛋白基因片段,未分离组均未检出扩增产物且背景较深。结论混匀加样方式进行高速Percoll密度梯度离心,合并收集组织细胞层下所有液体,是分离浮游生物的最有效方法。     

梯度洗脱反相高效液相色谱法测定粉萆薢与绵萆薢中薯蓣皂苷含量

目的 建立粉萆薢和绵萆薢中薯蓣皂苷含量的高效液相色谱测定方法。方法 色谱柱：Gemini C18（250 mm×4.60 mm，5 μm）；流动相：乙腈-0.1%磷酸水溶液，梯度洗脱；检测波长：203 nm；流速：0.8 ml/min；柱温：30 ℃。结果 薯蓣皂苷与其他成分分离良好，色谱峰面积与浓度呈良好的线性关系，线性范围为7.8～156.0 μg/ml（r=0.999 4），平均回收率分别为97.99%、97.82%。结论 梯度洗脱反相高效液相色谱法准确、简便、重现性好，可用于萆薢类药材的质量评价。     

北京市经济持续增长下的城-近郊人口分布合理性研究

本文利用北京市城区人口密度与近郊区人口密度的比作为反映人口分布的指标，通过对城近郊区人口密度及其变动与经济发展、城市交通、人均居住面积、绿地面积等因素的相关分析，阐明了人口分布变动主要取决于经济发展水平，城市交通、人均居住面积、绿地面积等因素是通过经济变量作用于人口因素，或人口因素通过经济变量作用于其他。最后，本文利用城近郊人口密度梯度与GDP的logistic曲线估计，对人口分布的合理性做进一步的分析。     

Comparison between Temperature Gradient Gel Electrophoresis of Bacterial 16S rDNA and Diatom Test for Diagnosis of Drowning

When a body is discovered in water, it is difficult to conclude whether the cause of death was drowning, even today. Although diatom testing by the digestive method is classical, we hypothesized that aquatic bacteria, as well as diatoms, might be detected in drowned bodies, and conducted temperature gradient gel electrophoresis (TGGE)‐targeting 16S rDNA. DNA was extracted from the site water, and from heart blood and liver samples from 27 bodies concluded as drowning deaths by autopsy and subjected to TGGE after amplification of 16S rDNA by polymerase chain reaction. We observed whether the feature point of each 16S rDNA from the site water and blood or liver samples matched. Considerably higher correspondence was observed in drowned bodies, and the rate was higher than that achieved with the digestive method. Moreover, TGGE is safer than the digestive method. Our study suggests that this method can aid diagnosis of drowning.     

人精浆SDS-聚丙烯酰胺梯度凝胶电泳谱型研究

本文采用SDS-聚丙烯酰胺梯度凝胶电泳(SDS-PAGGE)研究了102例中国正常男子精浆蛋白的电泳谱型,得到了具有精液特征性的,可与人阴道液、唾液、初乳及血清进行鉴别的人精浆蛋白电泳谱型,并可作为精斑的确证。另发现一种-83kd 变异型。频率为8. 82±2. 81%。提高了精斑的个人识别机率,在实际应用中取得了初步成效。     

微量血痕的MN血型检验方法

本文介绍了两种微量血痕的 MN 血型检验方法。1.低温减压解离法的要点是:(1)剪取0.3～0.5cm 长的血痕纱线,用甲醇固定并分离;(2)置凹玻璃板凹内,加适合于检验血痕血型的抗 M、抗 N 血清;(3)在负压760mmHg 环境中吸收20分钟,再置4℃环境中吸收20～30分钟;(4)将凹玻璃板置冰块上用冷盐水洗涤血痕纱线;(5)吸干洗涤过的血痕纱线,滴加0.5～1%相应型的红细胞盐水悬液,减压解离20分钟;(6)用镊子夹起血痕纱线放在有两滴盐水的载玻片上,加盖玻片;(7)室温20分钟后,用显微镜观察。2.载片热解离法基本同第一法。不同点如下:(1)经洗涤后的纱线置载玻片上,加相应型的0.05%盐水红细胞悬液;(2)在56℃环境中解离10分钟。本文还测定了低温减压解离法的灵敏度,并对其室温解离原理进行了讨论。     

宁夏农村人口梯度转移模式和途径——基于主体功能区建设的视角

随着主体功能区建设进程的加快,宁夏需要从限制开发区转移出来的农村人口会越来越多,农村人口梯度转移模式就是适应这一变化的一种农村人口转移模式,它对促进农村人口职业转变和空间转移,加快农村工业化、农业产业化、地区城镇化步伐,实现城乡统筹发展具有重大的理论和现实意义。     

Automated Classification of Epiphyses in the Distal Radius and Ulna using a Support Vector Machine

The aim of this study was to automatically classify epiphyses in the distal radius and ulna using a support vector machine (SVM) and to examine the accuracy of the epiphyseal growth grades generated by the support vector machine. X‐ray images of distal radii and ulnae were collected from 140 Chinese teenagers aged between 11.0 and 19.0 years. Epiphyseal growth of the two elements was classified into five grades. Features of each element were extracted using a histogram of oriented gradient (HOG), and models were established using support vector classification (SVC). The prediction results and the validity of the models were evaluated with a cross‐validation test and independent test for accuracy (P_A). Our findings suggest that this new technique for epiphyseal classification was successful and that an automated technique using an SVM is reliable and feasible, with a relative high accuracy for the models.     

Classification of firing pin impressions using HOG-SVM

Crimes, such as robbery and murder, often involve firearms. In order to assist with the investigation into the crime, firearm examiners are asked to determine whether cartridge cases found at a crime scene had been fired from a suspect's firearm. This examination is based on a comparison of the marks left on the surfaces of cartridge cases. Firing pin impressions can be one of the most commonly used of these marks. In this study, a total of nine Ruger model 10/22 semiautomatic rifles were used. Fifty cartridges were fired from each rifle. The cartridge cases were collected, and each firing pin impression was then cast and photographed using a comparison microscope. In this paper, we will describe how one may use a computer vision algorithm, the Histogram of Orientated Gradient (HOG), and a machine learning method, Support Vector Machines (SVMs), to classify images of firing pin impressions. Our method achieved a reasonably high accuracy at 93%. This can be used to associate a firearm with a cartridge case recovered from a scene. We also compared our method with other feature extraction algorithms. The comparison results showed that the HOG-SVM method had the highest performance in this classification task.     

Tracking Movement and Temperature Selection of Larvae of Two Forensically Important Blow Fly Species Within a “Maggot Mass”

The current study responds to the lack of understanding about the temperatures experienced by individual blow fly larvae within “maggot masses.” The temperature selection of both aggregating (in a mass) and nonaggregating larvae was compared and their pattern of movement assessed. Infrared imaging determined the temperatures within a mass and in the vicinity of the constituent individual larvae, whose movements were tracked by dyeing their tissues red. Individual Chrysomya rufifacies larvae selected temperatures above 27°C, significantly higher than the temperature selected by Calliphora vicina larvae (24.5°C). However, this same difference was not seen within a mass, with both species selecting temperatures around 28°C. Larval movement in a mass was nonrandom, indicating that larvae actively select their position in a mass. Furthermore, larvae have a strong tendency to select the hottest part of a mass; therefore, maximum mass temperatures might provide a reliable proxy for the actual temperatures experienced by larvae.