1,593 research outputs found
Accessing High Momentum States In Lattice QCD
Two measures are defined to evaluate the coupling strength of smeared
interpolating operators to hadronic states at a variety of momenta. Of
particular interest is the extent to which strong overlap can be obtained with
individual high-momentum states. This is vital to exploring hadronic structure
at high momentum transfers on the lattice and addressing interesting phenomena
observed experimentally. We consider a novel idea of altering the shape of the
smeared operator to match the Lorentz contraction of the probability
distribution of the high-momentum state, and show a reduction in the relative
error of the two-point function by employing this technique. Our most important
finding is that the overlap of the states becomes very sharp in the smearing
parameters at high momenta and fine tuning is required to ensure strong overlap
with these states.Comment: 10 page
Empirical ugri-UBVRc Transformations for Galaxies
We present empirical color transformations between Sloan Digital Sky Survey
ugri and Johnson-Cousins UBVRc photometry for nearby galaxies (D < 11 Mpc). We
use the Local Volume Legacy (LVL) galaxy sample where there are 90 galaxies
with overlapping observational coverage for these two filter sets. The LVL
galaxy sample consists of normal, non-starbursting galaxies. We also examine
how well the LVL galaxy colors are described by previous transformations
derived from standard calibration stars and model-based galaxy templates. We
find significant galaxy color scatter around most of the previous
transformation relationships. In addition, the previous transformations show
systematic offsets between transformed and observed galaxy colors which are
visible in observed color-color trends. The LVL-based transformations
show no systematic color offsets and reproduce the observed color-color galaxy
trends.Comment: Accepted for publication in MNRAS (9 pages, 6 figures, 4 tables
Spitzer Local Volume Legacy (LVL) SEDs and Physical Properties
We present the panchromatic spectral energy distributions (SEDs) of the Local
Volume Legacy (LVL) survey which consists of 258 nearby galaxies (11 Mpc).
The wavelength coverage spans the ultraviolet to the infrared (1500
to 24 m) which is utilized to derive global physical
properties (i.e., star formation rate, stellar mass, internal extinction due to
dust.). With these data, we find color-color relationships and correlated
trends between observed and physical properties (i.e., optical magnitudes and
dust properties, optical color and specific star formation rate, and
ultraviolet-infrared color and metallicity). The SEDs are binned by different
galaxy properties to reveal how each property affects the observed shape of
these SEDs. In addition, due to the volume-limited nature of LVL, we utilize
the dwarf-dominated galaxy sample to test star formation relationships
established with higher-mass galaxy samples. We find good agreement with the
star-forming "main-sequence" relationship, but find a systematic deviation in
the infrared "main-sequence" at low luminosities. This deviation is attributed
to suppressed polycyclic aromatic hydrocarbon (PAH) formation in low
metallicity environments and/or the destruction of PAHs in more intense
radiation fields occurring near a suggested threshold in sSFR at a value of
log() 10.2.Comment: Accepted for publication in MNRAS (15 pages, 14 figures, 1 table
The Spitzer Local Volume Legacy (LVL) Global Optical Photometry
We present the global optical photometry of 246 galaxies in the Local Volume
Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D <
11 Mpc) galaxies whose absolute B-band magnitude span a range of -9.6 < M_B <
-20.7 mag. A composite optical (UBVR) data set is constructed from observed
UBVR and SDSS ugriz imaging, where the ugriz magnitudes are transformed into
UBVR. We present photometry within three galaxy apertures defined at UV,
optical, and IR wavelengths. Flux comparisons between these apertures reveal
that the traditional optical R25 galaxy apertures do not fully encompass
extended sources. Using the larger IR apertures we find color-color
relationships where later-type spiral and irregular galaxies tend to be bluer
than earlier-type galaxies. These data provide the missing optical emission
from which future LVL studies can construct the full panchromatic
(UV-optical-IR) spectral energy distributions.Comment: Accepted for publication in MNRAS (9 pages, 5 figures, 5 tables
Targeting alphas can make coyote control more effective and socially acceptable
Research at the UC Hopland Research and Extension Center (HREC) has improved our understanding of how to reduce sheep depredation while minimizing the impact on coyotes. Analysis of a 14-year data set of HREC coyote-control efforts found that sheep depredation losses were not correlated with the number of coyotes removed in any of three time scales analyzed (yearly, seasonally and monthly) during corresponding intervals for the next 2 years. Field research using radiotelemetry to track coyotes supported and explained this finding. For example, in 1995, dominant âalphasâ from four territories were associated with 89% of 74 coyote-killed lambs; âbetasâ and transients were not associated with any of these kills. Relatively few coyotes were killing sheep, and these animals were difficult to capture by conventional methods at the time of year when depredation was highest. However, selective removal of only the problem alpha coyotes effectively reduced losses at HREC
Targeting alphas can make coyote control more effective and socially acceptable
Research at the UC Hopland Research and Extension Center (HREC) has improved our understanding of how to reduce sheep depredation while minimizing the impact on coyotes. Analysis of a 14-year data set of HREC coyote-control efforts found that sheep depredation losses were not correlated with the number of coyotes removed in any of three time scales analyzed (yearly, seasonally and monthly) during corresponding intervals for the next 2 years. Field research using radiotelemetry to track coyotes supported and explained this finding. For example, in 1995, dominant âalphasâ from four territories were associated with 89% of 74 coyote-killed lambs; âbetasâ and transients were not associated with any of these kills. Relatively few coyotes were killing sheep, and these animals were difficult to capture by conventional methods at the time of year when depredation was highest. However, selective removal of only the problem alpha coyotes effectively reduced losses at HREC
Subspecific Identification of Sharp-Tailed Grouse Samples from Montana
Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) historically occupied much of the shrub-steppe habitat of the intermountain west, ranging from interior British Columbia south to California and Colorado. The subspecies has been extirpated from most of its range and currently exists in only scattered isolated populations. The last remnant populations in western Montana were located in the Tobacco Valley near Eureka and the Blackfoot Valley near Helmville. However, those populations were extirpated during the previous decade and the subspecies can no longer be confirmed in the state. A rangewide genetic analysis of sharp-tailed grouse in 2006 documented restricted gene flow based on an analysis of 45 tissue samples taken from Montana birds east of the continental divide. We extended that earlier analysis with a total of 133 tissue samples, including samples from western Montana birds extracted from museum skins collected in 1897, and compared these samples to other genetic profiles reported from across the species range. We compared these samples to test for genetic differences in an area where the reported distribution of the Columbian subspecies is geographically near populations from the plains subspecies (T. p. jamesi). We were able to assign subspecies classification to 126 of the 133 Montana samples, including all samples from west of the Continental Divide. All Montana samples conclusively typed out to the Plains subspecies. Our analysis identified 3 similar genetic clusters across sharptail populations: (1) Alberta, Colorado, Montana, North Dakota, South Dakota and Nebraska, (2) Washington, British Columbia and western Idaho, and (3) Utah and southern Idaho. Both microsatellite and control region sequence data indicate that sharp-tailed grouse from all localities in Montana are molecularly most similar to populations from the plains regions of Alberta to Nebraska, indicating that Montana birds share a relatively recent molecular history. It does not appear that the Continental Divide is a current or historical barrier to gene flow in sharp-tailed grouse
Testing Diagnostics of Nuclear Activity and Star Formation in Galaxies at z>1
We present some of the first science data with the new Keck/MOSFIRE
instrument to test the effectiveness of different AGN/SF diagnostics at z~1.5.
MOSFIRE spectra were obtained in three H-band multi-slit masks in the GOODS-S
field, resulting in two hour exposures of 36 emission-line galaxies. We compare
X-ray data with the traditional emission-line ratio diagnostics and the
alternative mass-excitation and color-excitation diagrams, combining new
MOSFIRE infrared data with previous HST/WFC3 infrared spectra (from the 3D-HST
survey) and multiwavelength photometry. We demonstrate that a high [OIII]/Hb
ratio is insufficient as an AGN indicator at z>1. For the four X-ray detected
galaxies, the classic diagnostics ([OIII]/Hb vs. [NII]/Ha and [SII]/Ha) remain
consistent with X-ray AGN/SF classification. The X-ray data also suggest that
"composite" galaxies (with intermediate AGN/SF classification) host bona-fide
AGNs. Nearly 2/3 of the z~1.5 emission-line galaxies have nuclear activity
detected by either X-rays or the classic diagnostics. Compared to the X-ray and
line ratio classifications, the mass-excitation method remains effective at
z>1, but we show that the color-excitation method requires a new calibration to
successfully identify AGNs at these redshifts.Comment: 7 pages, 4 figures. Accepted to ApJ Letter
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