131 research outputs found

    X-ray imaging of the Seyfert 2 galaxy Circinus with Chandra

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    We present results from the zeroth-order imaging of a Chandra HETGS observation of the nearby Seyfert 2 galaxy Circinus. Twelve X-ray sources were detected in the ACIS-S image of the galaxy, embedded in diffuse X-ray emission. The latter shows a prominent (~18arcsec) soft ``plume'' in the N-W direction, coincident with the [OIII] ionization cone. The radial profiles of the brightest X-ray source at various energies are consistent with an unresolved (FWHM ~0.8arcsec) component, which we identify as the active nucleus, plus two extended components with FWHMs ~ 2.3arcsec and 18arcsec, respectively. In a radius of 3arcsec, the nucleus contributes roughly the same flux as the extended components at the softest energies (< 2 keV). However, at harder energies (> 2 keV), the contribution of the nucleus is dominant. The zeroth-order ACIS spectrum of the nucleus exhibits emission lines at both soft and hard X-rays, including a prominent Fe Kalpha line at 6.4 keV, showing that most of the X-ray lines previously detected with ASCA originate in a compact region (<15 pc). Based on its X-ray spectrum, we argue that the 2.3arcsec extended component is scattered nuclear radiation from nearby ionized gas. The large-scale extended component includes the emission from the N-W plume and possibly from the outer starburst ring.Comment: Figure 1 in color. ApJ Letters, in pres

    Influence of harvest processes on pork loin and ham quality

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    The purpose of this study was to determine the specific effects of extending the interval between dwell time and the duration of scalding on pork quality attributes. Sixty-four Duroc × Yorkshire pigs were randomly assigned to a 2 × 2 factorial treatment arrangement. Treatments included extending the dwell duration from 5 to 10 min and extending the scald duration from 5 to 8 min. All carcasses entered the cooler 50 min after exsanguination. At exsanguination, blood was collected for three 1-min intervals and then for a final 2-min period. Temperature and pH of the LM and semimembranosus muscle (SM) were measured at 45 min, and at 2, 4, 6, and 24 h postmortem (PM). Hunter L*, a*, and b* values were determined on the LM, SM, and biceps femoris (BF). Purge loss was measured on the SM, BF, and the sirloin end of the loin. Drip loss was measured in duplicate from LM chops after 1 and 5 d of storage. Warner-Bratzler shear force (WBS) measurements were determined on LM chops aged 1, 3, 5, and 7 d PM. Over 99% of the collected blood was obtained during the first 3 min after sticking. Carcasses scalded for 8 min had greater (P \u3c 0.05) semi-membranosus 2 h temperature (28.8°C) than carcasses scalded 5 min (27.3°C). An 8-min scald process resulted in longissimus dorsi chops with lower hue angle and greater WBS values than the 5-min scald process. Increasing dwell time from 5 to 10 min resulted in biceps femoris chops with greater hue angle and loin chops with greater WBS values at 3 d PM. Harvest processes did not significantly affect subjective quality scores, Hunter L* values, purge or drip loss. Lengthening the duration of dwell and scalding may result in a more rapid PM pH decline. Reducing the duration of scalding may lead to increased time for manual removal of hair. Because of differences in facilities, it is recommended that individual facilities monitor dwell and scald durations to determine how to best minimize time of entry into the cooler

    A Chandra Observation of the Circinus Galaxy

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    We report on a recent Chandra ACIS-S observation of the Circinus galaxy. These observations confirm that the nuclear spectrum results from reflection of a hard X-ray continuum by ``neutral'' matter. The nuclear X-ray emission is extended by \sim 60 pc in the general direction of the optical ``ionization cone''. An image in the Fe K\alpha line has been made and shows that this emission extends up to 200 pc from the nucleus. There is also large-scale X-ray emission both along and perpendicular to the galaxy disk. Thermal plasma models for this extended gas indicate temperatures kT \sim 0.6 keV, though cooler photoionized gas is also possible. The X-ray emission from gas in the disk is probably associated with the starburst ring of radius 150--250 pc. The gas extending \sim 600 pc perpendicular to the disk is closely correlated with the high-excitation optical-line emission. In addition to its soft X-ray emission, we tentatively detect a hard component from the gas above the plane; this hard emission may represent nuclear X-rays scattered into our line of sight by electrons in the outflowing wind. Ten compact sources are found in the central kpc of the galaxy. The most luminous has an X-ray luminosity of \simeq 10^{40} erg s^{-1} and seems to be an X-ray binary in the Circinus galaxy with a black-hole mass exceeding 80 M_{\odot}.Comment: 25 pages, 13 figures. Accepted for publication in The Astrophysical Journa

    Linking goniometer measurements to hyperspectral and multi-sensor imagery for retrieval of beach properties and coastal characterization

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    In June 2011, a multi-sensor airborne remote sensing campaign was flown at the Virginia Coast Reserve Long Term Ecological Research site with coordinated ground and water calibration and validation (cal/val) measurements. Remote sensing imagery acquired during the ten day exercise included hyperspectral imagery (CASI-1500), topographic LiDAR, and thermal infra-red imagery, all simultaneously from the same aircraft. Airborne synthetic aperture radar (SAR) data acquisition for a smaller subset of sites occurred in September 2011 (VCR\u2711). Focus areas for VCR\u2711 were properties of beaches and tidal flats and barrier island vegetation and, in the water column, shallow water bathymetry. On land, cal/val emphasized tidal flat and beach grain size distributions, density, moisture content, and other geotechnical properties such as shear and bearing strength (dynamic deflection modulus), which were related to hyperspectral BRDF measurements taken with the new NRL Goniometer for Outdoor Portable Hyperspectral Earth Reflectance (GOPHER). This builds on our earlier work at this site in 2007 related to beach properties and shallow water bathymetry. A priority for VCR\u2711 was to collect and model relationships between hyperspectral imagery, acquired from the aircraft at a variety of different phase angles, and geotechnical properties of beaches and tidal flats. One aspect of this effort was a demonstration that sand density differences are observable and consistent in reflectance spectra from GOPHER data, in CASI hyperspectral imagery, as well as in hyperspectral goniometer measurements conducted in our laboratory after VCR\u2711

    Maintenance of UK bread baking quality: Trends in wheat quality traits over 50 years of breeding and potential for future application of genomic-assisted selection

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    Improved selection of wheat varieties with high end-use quality contributes to sustainable food systems by ensuring productive crops are suitable for human consumption end-uses. Here, we investigated the genetic control and genomic prediction of milling and baking quality traits in a panel of 379 historic and elite, high-quality UK bread wheat (Triticum eastivum L.) varieties and breeding lines. Analysis of the panel showed that genetic diversity has not declined over recent decades of selective breeding while phenotypic analysis found a clear trend of increased loaf baking quality of modern milling wheats despite declining grain protein content. Genome-wide association analysis identified 24 quantitative trait loci (QTL) across all quality traits, many of which had pleiotropic effects. Changes in the frequency of positive alleles of QTL over recent decades reflected trends in trait variation and reveal where progress has historically been made for improved baking quality traits. It also demonstrates opportunities for marker-assisted selection for traits such as Hagberg falling number and specific weight that do not appear to have been improved by recent decades of phenotypic selection. We demonstrate that applying genomic prediction in a commercial wheat breeding program for expensive late-stage loaf baking quality traits outperforms phenotypic selection based on early-stage predictive quality traits. Finally, trait-assisted genomic prediction combining both phenotypic and genomic selection enabled slightly higher prediction accuracy, but genomic prediction alone was the most cost-effective selection strategy considering genotyping and phenotyping costs per sample

    Artillery Shells over Circinus

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    The recently identified Circinus Galaxy is the nearest (about 4 Mpc) Seyfert 2 galaxy known and we now demonstrate to be one of the best laboratories for studying the effects of nuclear activity on the surrounding environment. Here we present new imaging Fabry-Perot observations of Circinus which confirm the existence of an ionization cone in this object but also show for the first time a complex of ionized filaments extending radially from the nucleus out to distances of 1 kpc. Arcs suggestive of bow shocks are observed at the terminus of some of these filamentary structures. Most spectacular of all, one of the structures appears to be a scaled-up version of a Herbig-Haro jet. The velocity field of the filaments confirms that they represent material expelled from the nucleus (possibly in the form of `bullets') or entrained in a wide-angle wind roughly aligned with the polar axis of the galaxy. The motions observed across the ionization cone are highly supersonic, so high-velocity shocks are likely to contribute to the ionization of the line emitting gas. However, it is not clear at present whether shock ionization dominates over photoionization by the Seyfert 2 nucleus. Extrapolation of the filaments to smaller radii comes to within 1 arcsec (about 20 pc) of the infrared nucleus, therefore suggesting a AGN or nuclear starburst origin to these features. The complex of radial filaments detected in the Circinus galaxy is unique among active galaxies. The frequency of such events is unknown since only a handful of galaxies have been observed at the sensitivity level of our present observations. The event in the Circinus galaxy may represent a relatively common evolutionary phase in the lives of gas-rich active galaxies during which the dusty cocoon surrounding the nucleus is expelled by the action of jet or wind phenomena.Comment: 22 pages including 5 figures, Latex, requires aasms4.sty. To appear in ApJ Letters 479 (1997
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