298 research outputs found

    Effects of Tillage and Grass Filter Strips on Surface Runoff of Water, Nitrate, Sediment, and Atrazine

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    The contamination of streams and other natural bodies of water through agricultural runoff has become a very important environmental issue. Surface water runoff can contain heavy loads of sediment and/or agricultural chemicals, such as nitrogen and atrazine. Conservation tillage methods with vegetative filter strips downslope from cropped fields help· to combat this problem. Conservation tillage has proven effective in decreasing erosion by decreasing exposure of the soil surface to rainfall. Vegetative filter strips provide an area where sediment and agricultural chemicals from cropland can be deposited before the runoff reaches a body of water

    A Robust 43-GHz VCO in CMOS for OC-768 SONET Applications

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    In this paper, we present a 43-GHz LC-VCO in 0.13-/spl mu/m CMOS for use in SONET OC-768 optical networks. A tuned output buffer is used to provide 1.3 V/sub p-p/ (single-ended) into a 90-fF capacitive load as is required when the VCO is used in typical clock and data recovery (CDR) circuits. Phase noise is -90 dBc/Hz at a 1-MHz offset from the carrier; this meets SONET jitter specifications. The design has a tune range of 4.2%. The VCO, including output buffers, consumes 14 mA from a 1-V supply and occupies 0.06 mm/sup 2/ of die area. Modern CMOS process characteristics and the high center frequency of this design mean that the tank loss is not dominated by the integrated inductor, but rather by the tank capacitance. An area-efficient inductor design that does not require any optimization is used

    Soil Erosion with Different Tillage and Cropping Systems

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    Corn and soybeans are produced on approximately three million acres of Kentucky farmland each year. L 1ttle soil loss occurs when these crops are grown on nearly level or gently sloping land. However, much of the grain production is on sloping land that is cultivated every year and often excessive soil erosion occurs. If a field is allowed to erode excessively for several years, the soil usually becomes less productive. Soil removed in runoff may pollute lakes and streams or cover highly productive soil with low quality sediments

    The Ursinus Weekly, November 7, 1974

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    The Great Pumpkin comes to U.C. • Course Directory Catalogue Committee formed by U.S.G.A. • Antigone is ProTheatre\u27s production • Union does it again • Criminal law featured as Forum topic • Letters to the editor: Epitaph on an Ursinus transfer • Pages from Ursinus past: A legend • Perusing Pfahler\u27s pigeons • New Economics head • Equus reviewed • Concerts: Bizarre and sublime • Record review • Nate DuPree: Can a black man find happiness at Ursinus? • Martha Franklin: A half century of service to our students and campus • Readin\u27, ritin\u27 and new math • Introducing campus leaders • Football wrapup: Swarthmore; Widener • Hockey teams win the big games! • Harriers 6-4 on seasonhttps://digitalcommons.ursinus.edu/weekly/1024/thumbnail.jp

    Scope for Credit Risk Diversification

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    This paper considers a simple model of credit risk and derives the limit distribution of losses under different assumptions regarding the structure of systematic risk and the nature of exposure or firm heterogeneity. We derive fat-tailed correlated loss distributions arising from Gaussian risk factors and explore the potential for risk diversification. Where possible the results are generalised to non-Gaussian distributions. The theoretical results indicate that if the firm parameters are heterogeneous but come from a common distribution, for sufficiently large portfolios there is no scope for further risk reduction through active portfolio management. However, if the firm parameters come from different distributions, then further risk reduction is possible by changing the portfolio weights. In either case, neglecting parameter heterogeneity can lead to underestimation of expected losses. But, once expected losses are controlled for, neglecting parameter heterogeneity can lead to overestimation of risk, whether measured by unexpected loss or value-at-risk

    Cytosine-5 RNA methylation links protein synthesis to cell metabolism.

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    Posttranscriptional modifications in transfer RNA (tRNA) are often critical for normal development because they adapt protein synthesis rates to a dynamically changing microenvironment. However, the precise cellular mechanisms linking the extrinsic stimulus to the intrinsic RNA modification pathways remain largely unclear. Here, we identified the cytosine-5 RNA methyltransferase NSUN2 as a sensor for external stress stimuli. Exposure to oxidative stress efficiently repressed NSUN2, causing a reduction of methylation at specific tRNA sites. Using metabolic profiling, we showed that loss of tRNA methylation captured cells in a distinct catabolic state. Mechanistically, loss of NSUN2 altered the biogenesis of tRNA-derived noncoding fragments (tRFs) in response to stress, leading to impaired regulation of protein synthesis. The intracellular accumulation of a specific subset of tRFs correlated with the dynamic repression of global protein synthesis. Finally, NSUN2-driven RNA methylation was functionally required to adapt cell cycle progression to the early stress response. In summary, we revealed that changes in tRNA methylation profiles were sufficient to specify cellular metabolic states and efficiently adapt protein synthesis rates to cell stress.This work was funded by a Cancer Research UK Senior Fellowship (C10701/A15181), the European Research Council (ERC; 310360), and the Medical Research Council UK (MR/M01939X/1). Part of this work was carried out in the framework of the European COST action EPITRAN 16120. SK receives funding from the DFG (KE1943/3-1). The funders had no role in study design, data collection, and analysis, decision to publish, 5 or preparation of the manuscript

    The scene of the crime: inventing the serial killer

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    This article examines the meanings of the crime scene in serial killings, and the tensions between the real and the imagined in the circulation of those meanings. Starting with the Whitechapel Murders of 1888 it argues that they, as well as forming an origin for the construction of the identity of 'the serial killer', initiate certain ideas about the relationship of subjects to spaces and the existence of the self in the modern urban landscape. It suggests that these ideas come to play an integral part in the contemporary discourse of serial killing, both in the popular imagination and in professional analysis. Examining the Whitechapel Murders, more recent cases and modern profiling techniques, it argues that popular and professional representations of crime scenes reveal more of social anxieties about the nature of the public and the private than they do about serial killers. It suggests that 'the serial killer' is not a coherent type, but an invention produced from the confusions of persons and places. Copyright 2006 SAGE Publications. All rights reserved. Not for commercial use or unauthorized distribution
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