多种群遗传算法在微震震源定位中的应用

微震震源的精确和快速定位对坑道安全的预测至关重要。在设定均质均速模型条件下,两两检波器的观测走时和计算走时的拟合差绝对值之和为适应度函数,把微震震源定位转换为求解优化问题。采用格雷码对震源位置进行编码,提高了遗传算法的局部搜索能力;同时采用两个群体独立进化,分别利用轮盘和排序方法从两个群体中选择优秀个体,将各种群中的优秀个体进行交叉运算和变异产生新的个体,从而提高了遗传算法的全局搜索能力。通过实验证实优化后的遗传算法在微震震源定位中具有较高的性能和精度。     

iMole,a web based image retrieval system from biomedical literature

iMole is a platform that automatically extracts images and captions from biomedical literature. Images are tagged with terms contained in figure captions by means of a sophisticate text‐mining tool. Moreover, iMole allows the user to upload directly their own images within the database and manually tag images by curated dictionary. Using iMole the researchers can develop a proper biomedical image database, storing the images extracted from paper of interest, image found on the web repositories, and their own experimental images. In order to show the functioning of the platform, we used iMole to build a 2DE database. Briefly, tagged 2DE gel images were collected and stored in a searchable 2DE gel database, available to users through an interactive web interface. Images were obtained by automatically parsing 16 608 proteomic publications, which yielded more than 16 500 images. The database can be further expanded by users with images of interest trough a manual uploading process. iMole is available with a preloaded set of 2DE gel data at http://imole.biodigitalvalley.com .     

Heavy Metal Accumulation in Woodland Moss (Pleurozium Schreberi) in the Area Around a Chromium Opencast Mine at Kemi,and in the Area Around the Ferrochrome and Stainless Steel Works at Tornio,Northern Finland

Abstract

Woodland moss (Pleurozium schreberi) samples were collected at 52 sampling sites around a chromium opencast mine and around a ferrochrome and stainless steels works. The samples were dried, homogenized and digested with a mixture of concentrated nitric and perchloric acids. The Cr, Ni and Zn concentrations in the moss samples were determined by FAAS in order to clarify the aerial distribution of heavy metals from both the opencast chromium mine and the ferrochrome and stainless steel works. This study, carried out in 2000, compares the heavy metal (Cr, Ni, Zn) concentrations in mosses to the results of previous studies in 1995 and in 1990. According to the results, the average Ni concentrations (mean) in mosses have increased since 1990 along with increased Ni emissions from point sources, but the average Cr concentrations (mean) in mosses have increased despite the decrease in Cr emissions from point sources have decreased. The results have been discussed from various point of view, as well as depicted out the low deposition of Zn on mosses.     

Locally centred Mahalanobis distance: A new distance measure with salient features towards outlier detection

Outlier detection is a prerequisite to identify the presence of aberrant samples in a given set of data. The identification of such diverse data samples is significant particularly for multivariate data analysis where increasing data dimensionality can easily hinder the data exploration and such outliers often go undetected. This paper is aimed to introduce a novel Mahalanobis distance measure (namely, a pseudo-distance) termed as locally centred Mahalanobis distance, derived by centering the covariance matrix at each data sample rather than at the data centroid as in the classical covariance matrix. Two parameters, called as Remoteness and Isolation degree, were derived from the resulting pairwise distance matrix and their salient features facilitated a better identification of atypical samples isolated from the rest of the data, thus reflecting their potential application towards outlier detection. The Isolation degree demonstrated to be able to detect a new kind of outliers, that is, isolated samples within the data domain, thus resulting in a useful diagnostic tool to evaluate the reliability of predictions obtained by local models (e.g. k-NN models).     

Automatic knowledge extraction from chemical structures: the case of mutagenicity prediction

This work proposes a new structure–activity relationship (SAR) approach to mine molecular fragments that act as structural alerts for biological activity. The entire process is designed to fit with human reasoning, not only to make the predictions more reliable but also to permit clear control by the user in order to meet customized requirements. This approach has been tested on the mutagenicity endpoint, showing marked prediction skills and, more interestingly, bringing to the surface much of the knowledge already collected in the literature as well as new evidence.     

粗糙集方法及其在化学模式分类规则挖掘中的应用

简要介绍了粗糙集的基本概念,决策系统的约简步骤和分类规则的挖掘原理,提出了基于信息熵的数据离散化方法,使之充分结合粗糙集特性,具有良好的推广性。又以经典的橄榄油产地判别为例,采用粗糙集方法,无需先验知识,不用设定参数,即能消除冗余的属性和属性值,约简化学系统,从样本数据中挖掘出简明直接、易于理解的产生式分类规则,构建专业意义明确的化学模式分类模型,其预报性能良好,效果令人满意。     

基于熵学习机的恒星光谱分类

数据挖掘被广泛应用于恒星光谱分类。为了提高传统光谱分类方法性能,提出熵学习机(Entropy-based Learning Machine, ELM)。在该方法中,熵用来刻画分类的不确定性。为了得到理想的分类结果,分类的不确定性应最小,基于此,可得ELM的最优化问题。ELM在处理二分类问题和稀有光谱发现等方面具有一定优势。SDSS中K型、F型、G型恒星光谱数据集上的比较实验表明：ELM在进行恒星光谱分类时,其分类性能优于k近邻(k Nearest Neighbor)和支持向量机(Support Vector Machine)等传统分类方法。     

基于多层次模糊关联算法的通用航空产业知识挖掘研究

为挖掘通用航空产业领域知识的类型与发展规律,明确产业规划、推动产业健康发展,利用采集的3869份通用航空产业主题相关的网页资料,根据主题信息的关键词对通用航空产业领域知识进行分类,并基于多层次模糊关联算法进行知识挖掘分析.结果表明,通用航空产业领域知识中的通用航空产业主体与通用航空产业产品存在着紧密的联系和规则,而且采...     

Lone Pair…π Contacts and Structure Signatures of r(UNCG) Tetraloops,Z-Turns,and Z-Steps: A WebFR3D Survey

Z-DNA and Z-RNA have long appeared as oddities to nucleic acid scientists. However, their Z-step constituents are recurrently observed in all types of nucleic acid systems including ribosomes. Z-steps are NpN steps that are isostructural to Z-DNA CpG steps. Among their structural features, Z-steps are characterized by the presence of a lone pair…π contact that involves the stacking of the ribose O4′ atom of the first nucleotide with the 3′-face of the second nucleotide. Recently, it has been documented that the CpG step of the ubiquitous r(UNCG) tetraloops is a Z-step. Accordingly, such r(UNCG) conformations were called Z-turns. It has also been recognized that an r(GAAA) tetraloop in appropriate conditions can shapeshift to an unusual Z-turn conformation embedding an ApA Z-step. In this report, we explore the multiplicity of RNA motifs based on Z-steps by using the WebFR3D tool to which we added functionalities to be able to retrieve motifs containing lone pair…π contacts. Many examples that underscore the diversity and universality of these motifs are provided as well as tutorial guidance on using WebFR3D. In addition, this study provides an extensive survey of crystallographic, cryo-EM, NMR, and molecular dynamics studies on r(UNCG) tetraloops with a critical view on how to conduct database searches and exploit their results.