Application of scanning electron microscopy for pollution particle source determination in residential dust and soil

Many tons of electric furnace flue dust accumulated in an industrial area in Tifton, Georgia. Vehicles transporting the flue dust, classified as K061 hazardous waste because it contained lead and cadmium, initially dumped the material in a warehouse. Once the warehouse was full, the flue dust was dumped in uncovered piles. Run-off from the piles and wind-driven particles had the opportunity to contaminate nearby industries, residential buildings, and neighborhood soils over a period of many years. Scanning electron microscopy-energy dispersive x-ray spectrometry (SEM-EDS) was used to compare the morphology and chemical composition of fly ash dust from the suspect pile with samples collected from the surrounding buildings and soil. Adhesive samplers were used to collect dust that had accumulated in buildings surrounding the fly ash dump site. Suspect dust particles were analyzed by SEM-EDS and compared with known dust particles from the fly ash pile. Soil samples were dried, sieved, and the “fines” analyzed by SEM-EDS for comparison with samples from the fly ash pile. Fly ash particles similar in morphology and chemical composition to the fly ash in the suspect pile were identified in most of the buildings sampled surrounding the fly ash dump site and in all of the soil samples analyzed surrounding the dumpsite. This case study illustrates the usefulness of applying morphology and chemistry information acquired by SEM-EDS for pollution particle source determination.     

Prevalence rates and demographic characteristics associated with depression in pregnancy and the postpartum.

Examined the prevalence of depression in a heterogeneous sample of 360 pregnant women. Subjects were assessed with respect to both depressive symptomatology and diagnostic status during pregnancy and after delivery. At both assessments, approximately 25% of the sample reported elevated levels of depressive symptomatology. In contrast, 10% of the women met diagnostic criteria for depression during pregnancy, and 6.8% were depressed postpartum. However, only half of the cases of postpartum depression were new onset (3.4%); the remaining women receiving a diagnosis in the postpartum had also been depressed during pregnancy. Finally, depression during pregnancy was related to different sociodemographic variables than was postpartum depression, suggesting that depression at these two times may be associated with different psychological or etiological factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nodal probabilistic production cost simulation considering transmission system unavailabilty

A nodal probabilistic production cost simulation method is described for power system long-term expansion planning considering unavailability and delivery limitation constraints of the transmission system. This new nodal production cost simulation model includes capacity constraints and unavailabilities of generators as well as transmission lines. This simulation methodology comes from the nodal composite power system equivalent load duration curve (CMELDC), based on a new effective load model at load points developed by the authors. The nodal CMELDC can be obtained from convolution integral processing of the outage capacity probability distribution function of the fictitious generator and the original LDC. It is expected that the new simulation model based on the nodal CMELDC proposed here will provide solutions to many problems based on nodal and decentralised operation and control of electric power systems under a competition environment. The nodal CMELDC based on the new model at load points can extend application areas of nodal probabilistic production cost simulation, probabilistic congestion cost assessment, analytical outage cost assessment and nodal reliability evaluation and so on at load points. The characteristics and effectiveness of this new proposed methodology are illustrated by a small system case study using a network flow and enumeration method.     

An efficient k-means clustering algorithm: analysis andimplementation

In k-means clustering, we are given a set of n data points in d-dimensional space R^d and an integer k and the problem is to determine a set of k points in Rd, called centers, so as to minimize the mean squared distance from each data point to its nearest center. A popular heuristic for k-means clustering is Lloyd's (1982) algorithm. We present a simple and efficient implementation of Lloyd's k-means clustering algorithm, which we call the filtering algorithm. This algorithm is easy to implement, requiring a kd-tree as the only major data structure. We establish the practical efficiency of the filtering algorithm in two ways. First, we present a data-sensitive analysis of the algorithm's running time, which shows that the algorithm runs faster as the separation between clusters increases. Second, we present a number of empirical studies both on synthetically generated data and on real data sets from applications in color quantization, data compression, and image segmentation     

Efficient Randomized Algorithms for the Repeated Median Line Estimator

The problem of fitting a straight line to a finite collection of points in the plane is an important problem in statistical estimation. Recently there has been a great deal of interest is robust estimators, because of their lack of sensitivity to outlying data points. The basic measure of the robustness of an estimator is its breakdown point, that is, the fraction (up to 50%) of outlying data points that can corrupt the estimator. One problem with robust estimators is that achieving high breakdown points (near 50%) has proved to be computationally demanding. In this paper we present the best known theoretical algorithm and a practical subquadratic algorithm for computing a 50% breakdown point line estimator, the Siegel or repeated median line estimator. We first present an O(n\log n) randomized expected-time algorithm, where n is the number of given points. This algorithm relies, however, on sophisticated data structures. We also present a very simple O(n log ² n) randomized algorithm for this problem, which uses no complex data structures. We provide empirical evidence that, for many realistic input distributions, the running time of this second algorithm is actually O(n log n) expected time. Received January 25, 1995; revised May 17, 1996. Communciated by L. J. Guibas.     

Low-palmitic,low-linolenic soybean development

Plant breeding research efforts are currently focused on developing breeding procedures to decrease the saturated FA palmitic acid (16∶0) and the PUFA linolenic acid (18∶3) in U.S. soybean cultivars. Soybean oil with lower 16∶0 may provide cardiovascular benefits to health-conscious consumers, and lower 18∶3 could contribute to better flavor and stability of the oil. The purpose of this study was to determine genetic parameters that indicate the potential for breeding success and to characterize the correlated effect of the incorporation of the modified oil traits on the agronomic and seed quality traits of a soybean breeding population formed from a cross between the soybean cultivar Anand (normal) and germplasm N97-3708-13 (low 16∶0, low 18∶3). Although lines with only one modified oil quality trait (low 16∶0 or 18∶3) are useful as parents, commercial utilization requires productive cultivars with the combination of both oil traits. This paper shows the ease with which they may be combined with seed yield and other traits. Measurements were obtained from 179 F₂ single plants grown in 1999 and 121 F_2∶4 lines grown in replicated plots in 2000. Modified FA lines were developed with ca. 4% 16∶0 and 18∶3, respectively. Very weak positive correlations were found between 16∶0 concentration and seed yield (r=0.12) and between 16∶0 and seed oil concentration (r=0.13). No correlation was found between 18∶3 levels and seed yield, or between 18∶3 levels and seed oil concentration. These results indicate that breeding for reduced 16∶0 and 18∶3 should not have a negative impact on seed yield or oil concentration. 16∶0 and 18∶3 had moderately high heritabilities of 0.65 and 0.73, respectively. This indicates that breeders using low 16∶0, low 18∶3 germplasm in crosses with normal, elite lines can expect to recover low 16∶0 and low 18∶3 in pure line progenies via selection and generation advancement of F₂ individuals that express low levels of these FA.     

Method for testing the aquatic toxicity of sediment extracts for use in identifying organic toxicants in sediments

Biologically directed fractionation techniques are a fundamental tool for identifying the cause of toxicity in environmental samples, but few are available for studying mixtures of organic chemicals in aquatic sediments. This paper describes a method for extracting organic chemicals from sediments and then re-introducing them into water column toxicity tests in a way that mimics, at least in part, the partitioning processes that govern bioavailability in sediment. This involves transferring solvent extracts of sediment into triolein and then placing the mixture inside low-density polyethylene dialysis tubing in a configuration similar to semipermeable membrane devices (SPMDs) used for environmental monitoring. For four model compounds, SPMDs were shown to effectively maintain water column exposure in static systems for 10-14 d, with partition coefficients similar to K(OW). Toxicity tests indicated that the SPMDs were compatible with four of five freshwater organisms tested and could be used to measure both lethal and sublethal end points. An example application showed good correspondence between organism responses in intactsediment and extracts in SPMDsfor both field-collected and spiked sediments. The SPMD-based method offers a simple, flexible test design, amenable to several different test organisms, and the ability to work with complex mixtures of contaminants while maintaining partitioning behavior similar to that within intact sediments.     

The wear of copper in single-pass sliding

Copper pins were worn in single passes against glass countersurfaces. By observation through the glass it could be seen that direct interaction between the pin and the countersurface occurred only very close to the leading edge of the pins. Wear particles formed in this region were typically 30 nm in diameter and not more than 17 nm thick. Away from the leading edge wear took place by a series of processes involving first metallic and then oxide wear debris. To aid in the separation of these processes pins were worn from sharp wedges whereupon the wear stages developed sequentially from the trailing edge. The wear rate and coefficient of friction decreased progressively with increasing size of the pin in the direction of sliding and these values were used to calculate local wear constants, coefficients of friction and loading. In spite of appearances to the contrary, wear debris was found to reduce the severity of the interaction between the wearing surfaces.     

Plasticity of tonotopic maps in auditory midbrain following partial cochlear damage in the developing chinchilla

In order to analyze the immunopathologic mechanisms of Beh?et's disease, the gene (bes-1) encoding a streptococcal antigen correlated with the disease was cloned and sequenced, and protein produced by this clone was identified by Western immunoblotting using serum antibody from the patient. Cellular DNA of Streptococcus (S.) sanguis serotype KTH-1 (uncommon serotype 1, strain 113-20) from the patient was extracted and digested with EcoRI. The digested fragments were cloned into the cloning vector lambda gt11, and then the resulting DNA library was immunoscreened using the patient's serum antibody to serotype KTH-1. The immunopositive clone of the 1.5 kbp fragment was subcloned into pUC 118 plasmid (pU8BeS1-1) and sequenced. The sequence showed that the 3'-terminal half side region of this insert contained 962bp of open-reading frame (ORF) discontinued at the EcoRI restriction site, and the stop codon was not found. The nucleotide sequence of the remaining additional 3'-terminal region of this gene encoding whole BES-1 was determined by genome walking. The whole ORF of bes-1 consisted of 849 amino acid residues with a calculated molecular mass of 95 kDa. The residues in a portion of the amino acid sequence showed a 60% correspondence to those of the human intraocular peptide Brn-3b.     

Ballistic response of polymer composites

A new microvelocity sensor unit was developed to measure the instantaneous velocity of a projectile during the penetration process. The concept of this device is based on the induced current generated in a coil resulting from the passage of a magnet. A special digital circuit was designed to yield a spatial resolution of better than 2.5 mm by elimiating the problem of signal overlap. The time delays obtained from these signals were used to determine the slowing down or energy loss of a high velocity projectile. A light gas gun was used to propel aluminum projectiles to velocities up to 320 m/s. Energy loss of these high velocity projectiles in composites reinforced with polyethylene, polyester, and graphite fabrics was investigated. Two distinct energy loss mechanisms were detected, one due to the actual fracture process and the other to the generation of frictional heat. Extensive delamination was observed in the more ductile PE and PET composites, but not in graphite. Low velocity instrumented drop-tower impact tests were also conducted, using identical specimens and similar impact geometries.