2,361 research outputs found

    An investigation into wear characteristics of a direct drilling coulter (opener) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Agricultural Mechanisation at Massey University

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    Wear on a promising chisel coulter, developed at Massey University, was considered to be marginally unacceptable. A functional lifespan of approximately 20 hectares for non-rolling blade components necessitated relatively frequent coulter replacement, and thereby incurred increased costs for components and machine downtime. Three experiments were carried out with an improved version of the Massey University chisel coulter concept. The respective objectives were as follows: 1. To determine whether soil particles were passing between the rotating disc and stationary coulter blade components during normal field machine operation. 2. To determine the patterns of coulter blade wear. 3. To compare several selected blade treatments in their abilities to prolong functional coulter blade life. In the first (laboratory) experiment, a stationary test rig was constructed. This closely simulated coulter assembly operation in the field. Measurements of changes in soil particle size with time for "soil" and "no soil" introduction to the disc/blade interface did not detect any soil breakdown which might have indicated a soil "lubrication" effect at that interface. However, observations of the patterns of abrasion and of photographs did indicate that some form of soil "lubrication" had occurred. In the second experiment, a hard-facing welded (Hardcraft 700 over mild steel) and a control treatment (mild steel) were evaluated to establish patterns of wear on a three row field-operating test rig. The former treatment displayed potential for resisting dimensional changes at various stages throughout blade life. The rotating action of the disc against the inner shank of the blade was responsible, in the prevailing conditions, for wear at the inside lower leading edge/wing intersection of the blade. This action eventually accelerated wing wear. The weld bead pattern was modified for use in Run A of Experiment 3 (top pattern); and another pattern (bottom pattern) was designed to prevent possible increased penetration forces associated with the original weld pattern. The third experiment involved evaluation of selected treatments during routine field drilling operations, using a pre-production prototype direct drill. Carbonitrided mild steel blades offered an almost three-fold increase in relative wear resistance (in terms of metal weightloss per hectare) compared to the standard mild steel blades. The carbonitrided treatment also resisted dimensional changes more effectively, and was more cost effective than all other treatments. The influence on wing and shank dimensions exerted by left and right side blade positioning on each coulter assembly, appeared to reflect continual anti-clockwise machine cornering during operation and seed/fertiliser dispersal differences. Coulter wings on the outside of field turns were subjected to greatest wear, as were the shank regions of blades dispersing fertiliser. Lateral and fore/aft positioning of coulter assemblies appeared to have no effects on blade life

    The bear circadian clock doesn’t ‘sleep’ during winter dormancy

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    Most biological functions are synchronized to the environmental light:dark cycle via a circadian timekeeping system. Bears exhibit shallow torpor combined with metabolic suppression during winter dormancy. We sought to confirm that free-running circadian rhythms of body temperature (Tb) and activity were expressed in torpid grizzly (brown) bears and that they were functionally responsive to environmental light. We also measured activity and ambient light exposures in denning wild bears to determine if rhythms were evident and what the photic conditions of their natural dens were. Lastly, we used cultured skin fibroblasts obtained from captive torpid bears to assess molecular clock operation in peripheral tissues. Circadian parameters were estimated using robust wavelet transforms and maximum entropy spectral analyses

    San Francisco Delta Risk Assessment Year 1 Report Appendices

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    The Relative Contributions of Contaminants to Environmental Risk in the Upper San Francisco Estuary: Progress Report Year 1: Appendices Prepared for: The Metropolitan Water District of Southern California Prepared by: Wayne G. Landis, Steven R. Eikenbary, Ethan A. Brown, Colter P. Lemons, Emma E. Sharpe, and April J. Markiewicz Institute of Environmental Toxicology, Huxley College of the Environment Western Washington University Bellingham, WA 98225 June 30, 202

    San Francisco Delta Risk Assessment Year 1 Report

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    The Relative Contributions of Contaminants to Environmental Risk in the Upper San Francisco Estuary: Progress Report Year 1 Prepared for: The Metropolitan Water District of Southern California Prepared by: Wayne G. Landis, Steven R. Eikenbary, Ethan A. Brown, Colter P. Lemons, Emma E. Sharpe, and April J. Markiewicz Institute of Environmental Toxicology, Huxley College of the Environment Western Washington University Bellingham, WA 98225 June 30, 202

    Ischemic stroke risk, smoking, and the genetics of inflammation in a biracial population: the stroke prevention in young women study

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    <p>Abstract</p> <p>Background</p> <p>Although cigarette smoking is a well-established risk factor for vascular disease, the genetic mechanisms that link cigarette smoking to an increased incidence of stroke are not well understood. Genetic variations within the genes of the inflammatory pathways are thought to partially mediate this risk. Here we evaluate the association of several inflammatory gene single nucleotide polymorphisms (SNPs) with ischemic stroke risk among young women, further stratified by current cigarette smoking status.</p> <p>Methods</p> <p>A population-based case-control study of stroke among women aged 15–49 identified 224 cases of first ischemic stroke (47.3% African-American) and 211 age-comparable control subjects (43.1% African-American). Several inflammatory candidate gene SNPs chosen through literature review were genotyped in the study population and assessed for association with stroke and interaction with smoking status.</p> <p>Results</p> <p>Of the 8 SNPs (across 6 genes) analyzed, only <it>IL6 </it>SNP rs2069832 (allele C, African-American frequency = 92%, Caucasian frequency = 55%) was found to be significantly associated with stroke using an additive model, and this was only among African-Americans (age-adjusted: OR = 2.2, 95% CI = 1.0–5.0, p = 0.049; risk factor adjusted: OR = 2.5, 95% CI = 1.0–6.5, p = 0.05). When stratified by smoking status, two SNPs demonstrated statistically significant gene-environment interactions. First, the T allele (frequency = 5%) of <it>IL6 </it>SNP rs2069830 was found to be protective among non-smokers (OR = 0.30, 95% CI = 0.11–.082, p = 0.02), but not among smokers (OR = 1.63, 95% CI = 0.48–5.58, p = 0.43); genotype by smoking interaction (p = 0.036). Second, the C allele (frequency = 39%) of <it>CD14 </it>SNP rs2569190 was found to increase risk among smokers (OR = 2.05, 95% CI = 1.09–3.86, p = 0.03), but not among non-smokers (OR = 0.93, 95% CI = 0.62–1.39, p = 0.72); genotype by smoking interaction (p = 0.039).</p> <p>Conclusion</p> <p>This study demonstrates that inflammatory gene SNPs are associated with early-onset ischemic stroke among African-American women (<it>IL6</it>) and that cigarette smoking may modulate stroke risk through a gene-environment interaction (<it>IL6 and CD14</it>). Our finding replicates a prior study showing an interaction with smoking and the C allele of <it>CD14 </it>SNP rs2569190.</p

    Review of quantitative empirical evaluations of technology for people with visual impairments

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    Addressing the needs of visually impaired people is of continued interest in Human Computer Interaction (HCI) research. Yet, one of the major challenges facing researchers in this field continues to be how to design adequate quantitative empirical evaluation for these users in HCI. In this paper, we analyse a corpus of 178 papers on technologies designed for people with visual impairments, published since 1988, and including at least one quantitative empirical evaluation (243 evaluations in total). To inform future research in this area, we provide an overview, historic trends and a unified terminology to design and report quantitative empirical evaluations. We identify open issues and propose a set of guidelines to address them. Our analysis aims to facilitate and stimulate future research on this topic

    Report from UCSF.

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    Table S1. Body weights (kg) of captive bears just prior to entering winter dormancy. (PDF 630 kb

    LSST Science Book, Version 2.0

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    A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo
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