5,087 research outputs found
Water Quality Trends across Select 319 Monitoring Sites in Northwest Arkansas
Northwest Arkansas contains two 319 priority watersheds that the Arkansas Natural Resources Commission has identified as being impacted by point source and nonpoint source pollution (i.e., phosphorus, nitrogen, and sediment). This project specifically focused on determining water quality trends at select sites within the Illinois River (HUC# 11110103) and Beaver Reservoir (HUC# 11010001) priority watersheds, including Ballard Creek, Osage Creek, Illinois River, White River, West Fork White River and the Kings River where sufficient constituent data were available. Water quality trends were analyzed using flowâadjusted constituent concentrations of phosphorus, nitrogen, sediment, sulfate and chloride, and parametric and nonâparametric statistical techniques to determine if constituent concentrations were increasing, decreasing or not significantly changing over time. Overall, flowâadjusted concentrations of phosphorus and sediment have been decreasing across these watersheds based upon both statistical approaches. The decrease in phosphorus was likely the most important observation, because most water quality concerns in this region have focused on elevated phosphorus concentrations in these transboundary watersheds. These trends can be used along with other watershed information to improve the knowledge of how past, current, and future management decisions have influenced the watershed
Bull management for efficient reproduction
"Superior herd sires properly managed are the greatest asset in a cow-calf operation. Generally, the herd bull contributes 50 percent of the total genetic variation of your calf crop annually. In most closed herds, however, the past three herd sires contribute 85 to 90 percent of the total genetic variation in the herd. This high percentage is due to selection intensity or replacement rate of cows and bull."--First page.John W. Massey and Homer B. Sewell (Department of Animal Science, College of Agriculture)New 8/82/10
The Period-Luminosity Relation of Red Supergiant Stars in the Small Magellanic Cloud
The characteristics of light variation of RSGs in SMC are analyzed based on
the nearly 8-10 year long data collected by the ASAS and MACHO projects. The
identified 126 RSGs are classified into five categories accordingly: 20 with
poor photometry, 55 with no reliable period, 6 with semi-regular variation, 15
with Long Secondary Period (LSP) and distinguishable short period and 30 with
only LSP. For the semi-regular variables and the LSP variables with
distinguishable short period, the Ks band period-luminosity (P-L) relation is
analyzed and compared with that of the Galaxy, LMC and M33. It is found that
the RSGs in these galaxies obey similar P-L relation except the Galaxy. In
addition, the P-L relations in the infrared bands, namely the 2MASS JHKs,
Spitzer/IRAC and Spitzer/MIPS 24 {\mu}m bands, are derived with high
reliability. The best P-L relation occurs in the Spitzer/IRAC [3.6] and [4.5]
bands. Based on the comparison with the theoretical calculation of the P-L
relation, the mode of pulsation of RSGs in SMC is suggested to be the first
overtone radial mode.Comment: 82 pages, 31 figures, 6 tables, accepted for publication in Ap
Searching for "monogenic diabetes" in dogs using a candidate gene approach
BACKGROUND: Canine diabetes is a common endocrine disorder with an estimated breed-related prevalence ranging from 0.005% to 1.5% in pet dogs. Increased prevalence in some breeds suggests that diabetes in dogs is influenced by genetic factors and similarities between canine and human diabetes phenotypes suggest that the same genes might be associated with disease susceptibility in both species. Between 1-5% of human diabetes cases result from mutations in a single gene, including maturity onset diabetes of the adult (MODY) and neonatal diabetes mellitus (NDM). It is not clear whether monogenic forms of diabetes exist within some dog breeds. Identification of forms of canine monogenic diabetes could help to resolve the heterogeneity of the condition and lead to development of breed-specific genetic tests for diabetes susceptibility. RESULTS: Seventeen dog breeds were screened for single nucleotide polymorphisms (SNPs) in eighteen genes that have been associated with human MODY/NDM. Six SNP associations were found from five genes, with one gene (ZFP57) being associated in two different breeds. CONCLUSIONS: Some of the genes that have been associated with susceptibility to MODY and NDM in humans appear to also be associated with canine diabetes, although the limited number of associations identified in this study indicates canine diabetes is a heterogeneous condition and is most likely to be a polygenic trait in most dog breeds. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2052-6687-1-8) contains supplementary material, which is available to authorized users
Radio Weak Gravitational Lensing with VLA and MERLIN
We carry out an exploratory weak gravitational lensing analysis on a combined
VLA and MERLIN radio data set: a deep (3.3 micro-Jy beam^-1 rms noise) 1.4 GHz
image of the Hubble Deep Field North. We measure the shear estimator
distribution at this radio sensitivity for the first time, finding a similar
distribution to that of optical shear estimators for HST ACS data in this
field. We examine the residual systematics in shear estimation for the radio
data, and give cosmological constraints from radio-optical shear
cross-correlation functions. We emphasize the utility of cross-correlating
shear estimators from radio and optical data in order to reduce the impact of
systematics. Unexpectedly we find no evidence of correlation between optical
and radio intrinsic ellipticities of matched objects; this result improves the
properties of optical-radio lensing cross-correlations. We explore the
ellipticity distribution of the radio counterparts to optical sources
statistically, confirming the lack of correlation; as a result we suggest a
connected statistical approach to radio shear measurements.Comment: 16 pages with 19 figures, accepted for publication in MNRAS; Minor
corrections to section 6.3; 2 references adde
Red Supergiant Stars in the Large Magellanic Cloud: I. The Period-Luminosity Relation
From previous samples of Red Supergiants (RSGs) by various groups, 191
objects are assembled to compose a large sample of RSG candidates in LMC. For
189 of them, the identity as a RSG is verified by their brightness and color
indexes in several near- and mid-infrared bands related to the 2MASS JHKs bands
and the Spitzer/IRAC and Spitzer/MIPS bands. From the visual time-series
photometric observations by the ASAS and MACHO projects which cover nearly 8-10
years, the period and amplitude of light variation are analyzed carefully using
both the PDM and Period04 methods. According to the properties of light
variation, these objects are classified into five categories: (1) 20 objects
are saturated in photometry or located in crowded stellar field with poor
photometric results, (2) 35 objects with too complex variation to have any
certain period, (3) 23 objects with irregular variation, (4) 16 objects with
semi-regular variation, and (5) 95 objects with Long Secondary Period (LSP)
among which 31 have distinguishable short period, and 51 have a long period
shorter than 3000 days that can be determined with reasonable accuracy. For the
semi-regular variables and the LSP variables with distinguishable short period,
the period-luminosity relation is analyzed in the visual, near-infrared and
mid-infrared bands. It is found that the P-L relation is tight in the infrared
bands such as the 2MASS JHKs bands and the Spitzer/IRAC bands, in particular in
the Spitzer/IRAC [3.6] and [4.5] bands; meanwhile, the P-L relation is
relatively sparse in the V band which may be caused by the inhomogeneous
interstellar extinction. The results are compared with others' P-L
relationships for RSGs and the P-L sequences of red giants in LMC.Comment: 41 pages, 14 figures, 4 tables, accepted by Ap
Chen-Ruan cohomology of ADE singularities
We study Ruan's \textit{cohomological crepant resolution conjecture} for
orbifolds with transversal ADE singularities. In the -case we compute both
the Chen-Ruan cohomology ring and the quantum corrected
cohomology ring . The former is achieved in general, the
later up to some additional, technical assumptions. We construct an explicit
isomorphism between and in the -case,
verifying Ruan's conjecture. In the -case, the family
is not defined for . This implies that
the conjecture should be slightly modified. We propose a new conjecture in the
-case which we prove in the -case by constructing an explicit
isomorphism.Comment: This is a short version of my Ph.D. Thesis math.AG/0510528. Version
2: chapters 2,3,4 and 5 has been rewritten using the language of groupoids; a
link with the classical McKay correpondence is given. International Journal
of Mathematics (to appear
Spitzer SAGE-SMC Infrared Photometry of Massive Stars in the Small Magellanic Cloud
We present a catalog of 5324 massive stars in the Small Magellanic Cloud
(SMC), with accurate spectral types compiled from the literature, and a
photometric catalog for a subset of 3654 of these stars, with the goal of
exploring their infrared properties. The photometric catalog consists of stars
with infrared counterparts in the Spitzer, SAGE-SMC survey database, for which
we present uniform photometry from 0.3-24 um in the UBVIJHKs+IRAC+MIPS24 bands.
We compare the color magnitude diagrams and color-color diagrams to those of
the Large Magellanic Cloud (LMC), finding that the brightest infrared sources
in the SMC are also the red supergiants, supergiant B[e] (sgB[e]) stars,
luminous blue variables, and Wolf-Rayet stars, with the latter exhibiting less
infrared excess, the red supergiants being less dusty and the sgB[e] stars
being on average less luminous. Among the objects detected at 24 um are a few
very luminous hypergiants, 4 B-type stars with peculiar, flat spectral energy
distributions, and all 3 known luminous blue variables. We detect a distinct Be
star sequence, displaced to the red, and suggest a novel method of confirming
Be star candidates photometrically. We find a higher fraction of Oe and Be
stars among O and early-B stars in the SMC, respectively, when compared to the
LMC, and that the SMC Be stars occur at higher luminosities. We estimate
mass-loss rates for the red supergiants, confirming the correlation with
luminosity even at the metallicity of the SMC. Finally, we confirm the new
class of stars displaying composite A & F type spectra, the sgB[e] nature of
2dFS1804 and find the F0 supergiant 2dFS3528 to be a candidate luminous blue
variable with cold dust.Comment: 23 pages, 17 figures, 5 tables, accepted for publication in the
Astronomical Journa
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