17,919 research outputs found

    Development of an image converter of radical design

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    A long term investigation of thin film sensors, monolithic photo-field effect transistors, and epitaxially diffused phototransistors and photodiodes to meet requirements to produce acceptable all solid state, electronically scanned imaging system, led to the production of an advanced engineering model camera which employs a 200,000 element phototransistor array (organized in a matrix of 400 rows by 500 columns) to secure resolution comparable to commercial television. The full investigation is described for the period July 1962 through July 1972, and covers the following broad topics in detail: (1) sensor monoliths; (2) fabrication technology; (3) functional theory; (4) system methodology; and (5) deployment profile. A summary of the work and conclusions are given, along with extensive schematic diagrams of the final solid state imaging system product

    The APM Survey for Cool Carbon Stars in the Galactic Halo - II The Search for Dwarf Carbon Stars

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    We present proper motion measurements for carbon stars found during the APM Survey for Cool Carbon Stars in the Galactic Halo (Totten & Irwin, 1998). Measurements are obtained using a combination of POSSI, POSSII and UKST survey plates supplemented where necessary by CCD frames taken at the Isaac Newton Telescope. We find no significant proper motion for any of the new APM colour-selected carbon stars and so conclude that there are no dwarf carbon stars present within this sample. We also present proper motion measurements for three previously known dwarf carbon stars and demonstrate that these measurements agree favourably with those previously quoted in the literature, verifying our method of determining proper motions. Results from a complimentary program of JHK photometry obtained at the South African Astronomical Observatory are also presented. Dwarf carbon stars are believed to have anomalous near-infrared colours, and this feature is used for further investigation of the nature of the APM carbon stars. Our results support the use of JHK photomtery as a dwarf/giant discriminator and also reinforce the conclusion that none of the new APM-selected carbon stars are dwarfs. Finally, proper motion measurements combined with extant JHK photometry are presented for a sample of previously known Halo carbon stars, suggesting that one of these stars, CLS29, is likely to be a previously unrecognised dwarf carbon star.Comment: 13 pages, 5 figures, accepted for publication in MNRAS, Also available at http://www.astro.keele.ac.uk/~ejt/publications.htm

    Using Regression Discontinuity Design to Identify the Effect of Zoning

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    We test the effect of minimum lot zoning on rural-to-urban land use conversion using Regression Discontinuity Design (RDD), a technique that exploits natural discontinuities in the data to identify causal effects. Observations are drawn from either size of a discontinuous minimum lot size zoning boundary. Using these selected sub-samples, a binary discrete choice model of residential land use change is estimated using parcel-level data and other spatially explicit data from an exurban county that lies on the fringes of Cleveland, Ohio. Results show that controlling for unobserved correlation in the data clearly identifies a negative and significant effect of larger minimum lot size zoning on the probability of conversion to a residential use.Land Economics/Use,

    THE VALUE OF CLEAN DAIRY AIR: ACCOUNTING FOR ENDOGENEITY AND SPATIALLY CORRELATED ERRORS IN A HEDONIC ANALYSES OF THE IMPACT OF ANIMAL OPERATIONS ON LOCAL PROPERTY VALUES

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    We study the effect of livestock operations on property values using a hedonic analysis in five Ohio townships. Unlike previous studies, we account for endogenous livestock location variables and spatially correlated errors. Results suggest failure to correct for these problems results in biased estimates of livestock impacts on property values.Land Economics/Use,

    THE PRIVATE SECTOR APPROACH TO GRAIN MARKETING: THE CASE OF AGRICULTURAL MARKET ADVISORY SERVICES

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    The purpose of this paper is to investigate the pricing performance and behavior of market advisory services in corn and soybeans. Data on corn and soybean net price received for advisory services, as reported by the AgMAS Project, are available for the 1995, 1996 and 1997 marketing years. Performance test results suggest that, on average, market advisory services exhibit a small ability to "beat the market". This conclusion is somewhat sensitive to the type of performance test and market benchmark considered. The predictability results provide little evidence that future advisory service pricing performance can be predicted from past performance. Marketing profiles identify three marketing "styles": i) "scale-up" sales, ii) selective hedging and iii) "speculative" hedging. Advisory services tend to follow the same approach across crop years.Agribusiness,

    Chandra Observations of Low Mass X-ray Binaries and Diffuse Gas in the Early-Type Galaxies NGC 4365 and NGC 4382 (M85)

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    (Abridged) We used the Chandra X-ray Observatory ACIS S3 to image the X-ray faint elliptical galaxy NGC 4365 and lenticular galaxy NGC 4382. The observations resolve much of the X-ray emission into 99 and 58 sources, respectively, most of which are low-mass X-ray binaries (LMXBs) associated with each of the galaxies. We identify 18 out of the 37 X-ray sources in a central field in NGC 4365 with globular clusters. The luminosity functions of the resolved sources for both galaxies are best fit with cutoff power-laws whose cutoff luminosity is 0.93.1×1039\approx 0.9 - 3.1 \times 10^{39} ergs s1^{-1}. These luminosities are much larger than those previously measured for similar galaxies; we do not find evidence for a break in the luminosity function at the Eddington luminosity of a 1.4 MM_\odot neutron star. The spatial distributions of the resolved sources for both galaxies are broader than the distribution of optical stars. In both galaxies, a hard power-law model fits the summed spectrum of all of the sources. The unresolved emission is best fit by the sum of a soft mekal model representing emission from diffuse gas, and a hard power-law, presumed to be from unresolved LMXBs. A standard beta model fits the radial distribution of the diffuse gas in both galaxies. In the elliptical NGC 4365, the best-fit core radius is very small, while the S0 galaxy NGC 4382 has a larger core radius. This may indicate that the gas in NGC 4382 is rotating significantly.Comment: Astrophysical Journal, accepted: 38 pages with 20 embedded reduced resolution Postscript figure

    1995 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

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    The purpose of this research report is to present an evaluation of advisory service pricing performance in 1995 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1995. The average net advisory price across all 25 corn programs is 3.04perbushel.Therangeofnetadvisorypricesforcornisquitelarge,withaminimumof3.04 per bushel. The range of net advisory prices for corn is quite large, with a minimum of 2.34 per bushel and a maximum of 3.81perbushel.Theaveragenetadvisorypriceacrossall25soybeanprogramsis3.81 per bushel. The average net advisory price across all 25 soybean programs is 6.61 per bushel. As with corn, the range of net advisory prices for soybeans is substantial, with a minimum of 5.75perbushelandamaximumof5.75 per bushel and a maximum of 7.92 per bushel.Agricultural Market Advisory Service (AgMAS) Project, D4, D7, D8, G1, G2, H4, H8, Q1, Z1, Marketing,
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