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Search Results: 1 - 10 of 84491 matches for " Harland W. Epps "
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A New Solution for the Dispersive Element in Astronomical Spectrographs
Harland W. Epps,Judith G. Cohen,J. Christopher Clemens
Physics , 2009, DOI: 10.1086/650547
Abstract: We present a new solution for the dispersive element in astronomical spectrographs, which in many cases can provide an upgrade path to enhance the spectral resolution of existing moderate-resolution reflection-grating spectrographs. We demonstrate that in the case of LRIS-R at the Keck 1 Telescope a spectral resolution of 18,000 can be achieved with reasonable throughput under good seeing conditions.
The Location of the Nucleus and the Morphology of Emission-Line Regions in NGC 1068
Rodger I. Thompson,Ranga-Ram Chary,Michael R. Corbin,Harland Epps
Physics , 2001, DOI: 10.1086/323637
Abstract: This paper presents NICMOS images of the nucleus and emission line regions in NGC 1068. The location of the nucleus relative to the emission line features is established and the physics underlying the morphology is discussed.
The role that oilseeds, including new hi-oleic varieties can play in improving the profile of fat intake by the UK population  [PDF]
Janice Irene Harland
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.53024
Abstract:


The production in the EU of the oilseeds, rapeseed and sunflower, has increased dramatically over the last 20 years. Much of the oil produced after crushing is used for culinary purposes; this enhanced intake of vegetable oil has led to a substantial change of fatty acid (FA) supply. This has been conclusively demonstrated by taking the UK oil supply data and by use of the FA profile of the key oils converting the supply data into a FA profile of the UK market place for 2008-2012. The most marked changes are a reduction in saturated fat (SFA) and an increase in monounsaturated fatty acids (MUFA) available for consumption. Furthermore the introduction of varieties of hi-oleic sunflower oil can further affect the market FA profile. The fat profiles of rapeseed and sunflower oils are considered healthy and they can have a positive impact when included in the diet, particularly as a replacement for oils or fats rich in SFA. In the UK and much of Europe, adult SFA intake continues to exceed recommendations. While reductions in the UK population’s SFA intake have occurred over the last 20 years, these are modest and it may be timely to identify ways in which SFA intake can be further reduced. To do this, the UK market FA supply data has been analysed alongside the profile of FA intake from adults recording their intake in national dietary surveys in order to identify if the market supply affects overall FA consumption. There is an indication that market oil supply is reflected in adults dietary intake of the main groups of FA. Consequently changes made to the oil profile of oilseeds by plant breeders and use of the resulting healthier oils by food manufacturers could have important roles to play in helping adults to achieve the recommended intake of SFA and also improve the overall fat quality in their diet leading to enhanced long-term health and well-being. Thus changes made in pri

The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
Stephen Smee,James E. Gunn,Alan Uomoto,Natalie Roe,David Schlegel,Constance M. Rockosi,Michael A. Carr,French Leger,Kyle S. Dawson,Matthew D. Olmstead,Jon Brinkmann,Russell Owen,Robert H. Barkhouser,Klaus Honscheid,Paul Harding,Dan Long,Robert H. Lupton,Craig Loomis,Lauren Anderson,James Annis,Mariangela Bernardi,Vaishali Bhardwaj,Dmitry Bizyaev,Adam S. Bolton,Howard Brewington,John W. Briggs,Scott Burles,James G. Burns,Francisco Castander,Andrew Connolly,James R. Davenport,Garrett Ebelke,Harland Epps,Paul D. Feldman,Scott Friedman,Joshua Frieman,Timothy Heckman,Charles L. Hull,Gillian R. Knapp,David M. Lawrence,Jon Loveday,Edward J. Mannery,Elena Malanushenko,Viktor Malanushenko,Aronne Merrelli,Demitri Muna,Peter Newman,Robert C. Nichol,Daniel Oravetz,Kaike Pan,Adrian C. Pope,Paul G. Ricketts,Alaina Shelden,Dale Sandford,Walter Siegmund,Audrey Simmons,D. Smith,Stephanie Snedden,Donald P. Schneider,Michael Strauss,Mark SubbaRao,Christy Tremonti,Patrick Waddell,Donald G. York
Physics , 2012, DOI: 10.1088/0004-6256/146/2/32
Abstract: We present the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999 on the 2.5-m aperture Sloan Telescope at Apache Point Observatory, the spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II surveys, enabling a wide variety of Galactic and extra-galactic science including the first observation of baryon acoustic oscillations in 2005. The spectrographs were upgraded in 2009 and are currently in use for BOSS, the flagship survey of the third-generation SDSS-III project. BOSS will measure redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyman-alpha absorption of 160,000 high redshift quasars over 10,000 square degrees of sky, making percent level measurements of the absolute cosmic distance scale of the Universe and placing tight constraints on the equation of state of dark energy. The twin multi-object fiber spectrographs utilize a simple optical layout with reflective collimators, gratings, all-refractive cameras, and state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in two channels over a bandpass covering the near ultraviolet to the near infrared, with a resolving power R = \lambda/FWHM ~ 2000. Building on proven heritage, the spectrographs were upgraded for BOSS with volume-phase holographic gratings and modern CCD detectors, improving the peak throughput by nearly a factor of two, extending the bandpass to cover 360 < \lambda < 1000 nm, and increasing the number of fibers from 640 to 1000 per exposure. In this paper we describe the original SDSS spectrograph design and the upgrades implemented for BOSS, and document the predicted and measured performances.
A Hybrid Technique for the Periodicity Characterization of Genomic Sequence Data
Julien Epps
EURASIP Journal on Bioinformatics and Systems Biology , 2009, DOI: 10.1155/2009/924601
Abstract: The detection of structure within the DNA sequence has long captivated the interest of the research community. Among the various statistical characterizations of sequence data, one measure of structure within sequences is the degree of correlation or periodicity at various displacements along the sequence. Periodicity characterization of sequence data provides a compact and informative representation that has been used in many studies of structure within genomic sequences, including DNA sequence analysis [1], gene and exon detection [2], tandem repeat detection [3], and DNA sequence search and retrieval [4].To measure such periodicity, autocorrelation has been widely employed [1, 5–11]. Similarly, Fourier analysis and its variants have been used for periodicity characterization of sequences [4, 9, 12–24]. In some cases [25, 26], the Fourier transform of the autocorrelation sequence has also been computed, however using existing symbolic-numeric mappings such as binary indicator sequences [27], this transform can also be calculated without first determining the autocorrelation. Other recent promising approaches to periodicity characterization for biological sequences include the periodicity transform [28], the exactly periodic subspace decomposition [3], and maximum-likelihood statistical periodicity [29], however these techniques have yet to be adopted by biologists for the purposes of sequence structure characterization.Studies of structure within sequences, such as those referenced above, have tended to use either the autocorrelation or the Fourier transform, and to the author's knowledge, the limitations of each have not been compared in this context. In this paper, the limitations of both approaches are investigated using synthetic symbolic sequences, and caveats to their characterization of sequence data are discussed. A hybrid approach to periodicity characterization of symbolic sequence data is introduced, and its use is illustrated in a comparative manner on
Who Works Where:
Brad Epps
Hispanic Issues On Line , 2006,
Abstract:
A Hybrid Technique for the Periodicity Characterization of Genomic Sequence Data
Epps Julien
EURASIP Journal on Bioinformatics and Systems Biology , 2009,
Abstract: Many studies of biological sequence data have examined sequence structure in terms of periodicity, and various methods for measuring periodicity have been suggested for this purpose. This paper compares two such methods, autocorrelation and the Fourier transform, using synthetic periodic sequences, and explains the differences in periodicity estimates produced by each. A hybrid autocorrelationa€”integer period discrete Fourier transform is proposed that combines the advantages of both techniques. Collectively, this representation and a recently proposed variant on the discrete Fourier transform offer alternatives to the widely used autocorrelation for the periodicity characterization of sequence data. Finally, these methods are compared for various tetramers of interest in C. elegans chromosome I.
The SIDE dual VIS-NIR fiber fed spectrograph for the 10.4 m Gran Telescopio Canarias
O. Rabaza,H. W. Epps,M. Ubierna,J. Sanchez,M. Azzaro,F. Prada
Physics , 2008, DOI: 10.1117/12.787357
Abstract: SIDE (Super Ifu Deployable Experiment) is proposed as second-generation, common-user instrument for the GTC. It will be a low and intermediate resolution fiber fed spectrograph, highly efficient in multi-object and 3D spectroscopy. The low resolution part (R = 1500, 4000) is called Dual VIS-NIR because it will observe in the VIS and NIR bands (0.4 ~V 1.7 microns) simultaneously. Because of the large number of fibers, a set of ~10 identical spectrographs is needed, each with a mirror collimator, a dichroic and two refractive cameras. The cameras are optimized for 0.4 - 0.95 microns (VIS) and 0.95 - 1.7 microns (NIR) respectively.
A New Observational Upper Limit to the Low Redshift Ionizing Background Radiation
R. J. Weymann,S. N. Vogel,S. Veilleux,H. W. Epps
Physics , 2001, DOI: 10.1086/323205
Abstract: We report a new Fabry-Perot search for Halpha emission from the intergalactic cloud HI 1225+01 in an attempt to measure the low redshift ionizing background radiation. We set a new 2 sigma upper limit on Halpha emission of 8 mR (5 x 10^{-20} ergs cm^{-2} s^{-1} arcsec^{-2}). Conversion of this limit to limits on the strength of the ionizing background requires knowledge of the ratio of the projected to total surface area of this cloud, which is uncertain. We discuss the plausible range of this ratio, and within this range find that the strength of the ionizing backround is in the lower range of, but consistent with, previous observational and theoretical estimates.
Topological energy bounds for the Skyrme and Faddeev models with massive pions
Derek Harland
Physics , 2013, DOI: 10.1016/j.physletb.2013.11.062
Abstract: A topological lower bound on the Skyrme energy which depends explicity on the pion mass is derived. This bound coincides with the previously best known bound when the pion mass vanishes, and improves on it whenever the pion mass is non-zero. The new bound can in particular circumstances be saturated. New energy bounds are also derived for the Skyrme model on a compact manifold, for the Faddeev-Skyrme model with a potential term, and for the Aratyn-Ferreira-Zimerman and Nicole models.
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