Graphical interpretation of water quality data

Management of our nation's water resources through planning and control of water pollution hinges on the availability and interpretation of water quality data on which to base management decisions. This paper is aimed at exploring graphical methods which allow rapid and informative analysis of water quality data. The graphical methods presented in this paper fall into two main categories. The first category relates to graphical procedures which are developed as part of a statistical test, such as discriminant analysis. The second category involves approximation of multivariate water quality data into two dimensions. The methods for accomplishing the latter are canonical decomposition and high-dimensional plotting. Each of these methods is developed and used on an example set of data to demonstrate their utility. These methods seek to not only present a graphical representation of the data, but also to explain variations and interrelationships within the data itself.     

Analysis of toxicology data with covariates specific to each observation

The standard approach for analysis of teratology studiesis to use a population-averaged model with primary interest on evaluating dose-response effects. For example, generalized estimating equations (GEEs) have become popular for analysis of both developmental toxicity and reproducti vestudies (Ryan 1992). Such an approach is typically appropriate since the covariate of interest—exposure level—is constant for each litter of animals. Recently, however, there has been growing interest in evaluating effects of covariates that can vary between individuals within a cluster. This article explores several opportunities generated by teratology studies with individual-level covariates both in terms of modeling approaches and in decomposition of litter effects into genetic and environmental components.     

Analysis of water quality data using spectral analysis

Considerable effort has been expended by many State, Federal and private agencies in collecting data by installing automatic water quality monitoring stations on many streams and estuaries. This work discusses techniques for analyzing the data and presents some results based on the analysis of monitoring stations along the Ohio, Detroit, Missouri, and Coosa Rivers. Autocorrelation, spectral estimates, cross correlation, amplitude of transfer function and coherence square have been evaluated to correlate a water quality variable measured at different positions or different variables measured at the same location. Results from the different rivers have been compared and some conclusions have been drawn.     

An application of ranked set sampling for mean and median estimation using USDA crop production data

Ranked set sampling (RSS) is a sampling approach that leads to improved statistical inference in situations where the units to be sampled can be ranked (either through some subjective judgment or via the use of an auxiliary variable) relative to each other prior to formal measurement. It has the most promise for leading to improved methodology in situations where ranking of the items to be sampled can be carried out relatively easily and cheaply compared to the effort and expense required for actual quantification of the characteristic of interest. Although the theoretical benefits of RSS in estimation and statistical inference have been extensively demonstrated in the literature, the methodology has not yet been widely adopted by practitioners. The aim of this study is to use a crop production dataset from the United States Department of Agriculture to demonstrate the practical benefits of RSS relative to the more commonly used simple random sampling in estimation of the mean and median of a population. The results of our study provide clear evidence that the use of RSS can lead to substantial gains in precision of estimation for both of these situations.     

基于粗糙集和突变级数法的区域水资源可持续利用评价

为减少评价过程中指标信息筛选和权重赋予的人为主观影响,提出粗糙集和突变级数相耦合的区域水资源可持续利用评价方法.以福建省为例,以9个设区市为研究单元,从水资源条件、开发利用、生态环境和经济社会等方面,构建由4大准则20项指标组成的指标体系,进行水资源可持续利用评价.结果表明：1）应用粗糙集约简冗余指标,依据属性重要度对指标排序,并耦合突变级数法进行水资源可持续利用评价是可行的,不仅可筛除冗余指标信息,而且无需过多人工干预,可很大程度地减少人为主观影响;2）福建省各设区市水资源可持续利用水平排序为龙岩＞三明＞宁德＞南平＞漳州＞福州＞泉州＞莆田＞厦门,呈现自西向东、西北向东南可持续利用水平递减的空间格局,且根据评价结果划分的4个可持续利用分区,可为水资源分区开发利用和管理保护提供理论依据.     

基于SQLServer的二进制文件存储技术

文章分析了文件系统存储技术和SQLSERVER数据库存储的优缺点,阐述了企业进行商品推广时,二进制数据文件特别是图像文件的存储于SQLSERVER中的设想,并给出数据存储的例子     

A minimum data set for soil quality assessment of wheat and maize cropping in the highlands of Mexico

The objective was to establish a minimum soil quality dataset for a long-term tillage, residue management and rotation trial for wheat (Triticum aestivum L.) and maize (Zea mays L.) production systems. Based on this soil quality evaluation, sustainable management practices could be selected for transferring technologies to farmers in the region. A long-term experiment was conducted with 16 different crop management practices varying in: (1) rotation (continuous maize or wheat and both phases of the rotation of maize and wheat), (2) tillage (conventional and zero) and (3) crop residue management (full retention or removal for fodder). Superior soil quality was considered to represent the maintenance of high productivity without significant soil or environmental degradation. The pertinent, minimum soil quality data set included the following physical indicators: time-to-pond, aggregate stability, permanent wilting point, and topsoil penetration resistance. Chemical indicators were: soil C, N, K and Zn concentrations, measured in the 0–5 cm topsoil and C, N concentration in 5–20 cm. Multivariate analysis grouped the treatments into clusters: (1) zero tillage with retention of residue, (2) zero tillage with residue removal and (3) conventional tillage. Zero tillage combined with crop residue retention improved chemical and physical conditions of the soil. In contrast, zero tillage with removal of residues, led to high accumulation of Mn in the topsoil, low aggregate stability, high penetration resistance, surface slaking resulting in low time-to-pond values and high runoff. Finally, soil quality under conventional tillage was intermediate (irrespective of residue management), especially reflected in the physical status of the soil. The results provide a strong justification to promote zero tillage technology combined with appropriate residue management to farmers in the volcanic highlands of Central Mexico and other similar regions. The minimum data set and associated tools for careful monitoring and observation, will be essential for evaluating soil quality in farmer's fields.     

Soil sampling based on field spatial variability of soil microbial indicators

Microbial indicators exhibit a high spatial heterogeneity which often masks comparison of the effects of different soil management treatments. It is therefore desirable to use a proper sampling design which integrates spatial heterogeneity at field level. Thus, the objectives were: (1) to study the spatial heterogeneity of biological and chemical soil variables, and (2) with obtained maps of spatial variability to test different sampling strategies to assess the usefulness of this ‘new’ soil map unit. 63 soil samples were collected according to a 10 m × 10 m grid on a 0.48 ha plot. On each of these samples, 10 variables were measured: soil water content, cation exchange capacity (CEC), organic carbon (OC) and total nitrogen (N), C/N, soil microbial biomass (SMB), labile soil organic matter (LOM), mineralisable C (C_min) and N (N_min), inverse of specific respiratory activity (1/SRA = SBM/C_min). The spatial heterogeneity of each variable was charted with geostatistics. The biological variables exhibited spatial variability of the same order of magnitude as physicochemical parameters. From the maps, zones with different levels of organic matter, microbial biomass and specific respiratory activity were identified. The spatial patterns of SMB and SRA were related to CEC (positively for SMB and negatively for SRA), pointing out the effects of soil protection on microbial biomass and availability of organic substrates. The definition of these zones for a pool of variables (OC, N, SMB, LOM, CEC) is useful at 3 levels: (1) to record the initial values of the measured variables for each plot, (2) to integrate these zones as blocks in experimental design for future experiments, and (3) to focus analysis of specific biological mechanisms such as activity of micro-organisms.     

Bayesian estimation of cluster-level test accuracy based on different sampling schemes

We develop Bayesian models to estimate cluster-level test characteristics, sensitivity, specificity, prevalence, and predictive values, based on four different sampling schemes: a single test case and three sequential test cases. The corresponding cluster-level characteristics are calculated and compared for different sample sizes, sampling schemes, individual-level sensitivities, specificities, and cut-off values. We compared posterior estimates of individual-level and cluster-level characteristics for these four sampling schemes with simulated data. Two illustrations, one for Johne’s disease in cattle and another for Salmonella in pig herds, are used to demonstrate application of the methods.     

水氮运筹与强筋小麦产量和品质关系研究

研究结果表明：小麦的子粒产量和品质与氮肥的施用及氮肥和浇水的配合有密切关系，拔节和开花期追氮结合浇水对产量有明显增加作用；水氮配合施用可显著提高子粒品质，开花期追氮对子粒蛋白质作用明显，药隔期追氮稳定时间最长，拔节期大量浇水显著降低稳定时间，开花和药隔期追氮结合浇水对子粒品质作用最大。产量和子粒主要品质（蛋白质、湿面筋、稳定时间）表现最佳的结合点是拔节和开花期的水氮配合施用。     

Comparison of regulatory estimates of drinking water concentrations with monitoring data

Currently, regulatory practice in the United States is to estimate potential concentrations in drinking water from surface water by using an index reservoir scenario. This approach extrapolates results from the modeling of a single field with maximum application rates to the watershed scale, based on a percent crop area estimate. Since 1998, Bayer CropScience and its predecessor companies have conducted drinking water monitoring studies with a number of different compounds. The results from these studies show that the index reservoir scenario greatly overpredicts residues in surface water. The most important factor is the overestimation of use within a watershed. Other factors contributing to the overestimation of concentrations are the conservative procedures used to obtain the chemical fate related input parameters and the simplified hydrology. A new procedure based on the USGS WARP model, being developed by a group of scientists from the EPA, USGS, USDA, and industry, will provide more realistic estimates of concentrations of pesticides and their metabolites in drinking water.     

基于关联规则数据挖掘算法的应用

数据挖掘,又称数据库中的知识发现,作为一门新兴的研究领域,主要目的是从数据集合中发现隐含的、事先未知的、对决策有潜在价值的用户感兴趣的知识,数据挖掘是当前数据库领域中最受瞩目的研究方向之一。在数据挖掘研究中,关联规则挖掘作为数据挖掘研究中的一个重要部分,引起了越来越多的关注。本文利用SQL Server 2005数据挖掘工具,对已测得的土壤数据,利用关联规则算法对土壤的地力等级进行了预测。     

二进制与十进制动态显示的关键技术

二进制是计算机中所采用的数据表示形式,在文章中介绍了基于VRML与JAVA的虚拟动态交互技术,分析了利用Java或JavaScript语言创建出新的内插节点和传感节点来驱动和控制整个虚拟空间的方法,研究了利用VRML和Java的技术去设计动态交互的场景,实现了二进制与十进制之间的动态交互显示,最后指出该系统已被成功运用于教学,文章的创新点在于利用PRO/E优化建模。     

Genetic diversity and sampling strategy of Scutellaria baicalensis germplasm resources based on ISSR

Destruction in wild resource and decline in genetic diversity of Scutellaria baicalensis are becoming a big problem urgently needed be dealt in China. To help efficiently utilize and conserve this medicinal plant resources, ISSR analysis was employed to reveal genetic diversity of 107 S. baicalensis accessions consisting of 82 wild and 25 cultivated germplasm resources from 6 populations in two main producing provinces in China. Only eighteen ISSR primers that resulted in accuracy and credibility, high polymorphism, well stability PCR products were selected. The maximal and minimal bands resulted from an ISSR primer are 35 and 18 respectively with a total of 480 bands were resolved in the agarose gels with an average of two alleles per locus. As indicated by the index of genetic diversity (Na = 1.96, Ne = 1.39, He = 0.25, I = 0.39), there were richness of genetic diversity in the collected samples and that the S. baicalensis germplasm had a large representativeness as primary collection. Cluster analysis by UPGMA and STRUCTURE placed the 107-germplasm resources into three linkage clusters. The samples from all the collection locations were clustered together, but the populations from one province were not clustered together. Compared to the RS and SW strategies, the LDSS proved to be more representative for core collection construct of S. baicalensis and the best sampling ratio was 10.3 % of the total germplasms. Finally, we found that the mini core collection by LDSS was composed of 11 accessions with high genetic diversity (Na = 1.82, Ne = 1.40, He = 0.25, I = 0.39). To verify the reliability of sampling strategy, the t test was used to evaluate the representativeness between core collections (constructed by LDSS), primary and reserve collection. Our results showed that no significant difference was found in the two important genetic parameters He and I (P > 0.05), thus suggesting that the LDSS will provide a rational sampling strategy for constructing a core collection of S. baicalensis germplasm resources in the future.     

中小型水利工程施工质量问题探讨

中小型水利工程具有规模小、投资少、工期短等特点,施工单位一般设备较差,技术队伍的整体水平较低,工程质量很难达到高标准。为了实现质量、投资、工期三大控制,监理工作应及早介入并贯穿于工程建设的全过程。     

Studies on bacteriological quality of nainital lake water in different seasons

The total coliform and E. coli load of Nainital lake water in different seasons has been studied. The variation of these organisms with season, rainfall and human activities in the catchment area were observed.     

基于JAVA的批量数据导入导出探讨

本文介绍在WEB应用系统中实现基于Java的数据导入导出的技术与方法,并给出该方法在中国农业大学学生体质测试系统中的具体应用,本方法主要采用了Java语言以及JXL,Spring等开源技术。     

Impact of irrigation water quality on soil nitrifying and total bacterial communities

Disturbance induced by two contrasting irrigation regimes (groundwater versus urban wastewater) was evaluated on a sandy agricultural soil through chemical and microbial analyses. Contrary to wastewater, groundwater displayed very high nitrate contents but small amounts of ammonium and organic matter. Despite these strong compositional shifts, soil organic carbon and nitrogen, nitrate and ammonium contents were not significantly different in both types of irrigated plot. Moreover, neither microbial biomass nor its activity, determined as fluorescein diacetate hydrolysis activity, was influenced by irrigation regimes. Bacterial community structure, assessed by denaturing gradient gel electrophoresis (DGGE) of 16S ribosomal DNA fragments, was also weakly impacted as molecular fingerprints shared an overall similarity of 85%. Ammonia-oxidizing bacterial community (AOB) was monitored by DGGE of the functional molecular marker amoA gene (alpha subunit of the ammonia monooxygenase). Surprisingly, no amoA signals were obtained from plots irrigated with groundwater, whereas signal intensities were high in all plots under wastewater. Among the last, compositional shifts of the AOB community were weak. Overall, impact of irrigation water quality on soil chemistry could not be evidenced, whereas effects were low on the total bacterial compartment but marked on the AOB community.