495 research outputs found
Nutritive Levels in Plants from Stripmined Areas in Eastern Ohio
Author Institution: Ohio Cooperative Wildlife Research Unit, The Ohio State UniversityData on nutritive quality of vegetation for stripmined lands were obtained in 1972-73 from 2 Ohio counties, one having generally acidic spoil banks and the other having calcareous spoils. Proximate analysis of water, ash, crude protein, ether extract, cell-wall constituents, and nitrogen-free extract revealed few significant differences between plants growing on stripped and undisturbed (control) plots. Plants also were analyzed for 6 essential elements by emission spectrography. Levels of potassium were significantly higher in plants from control plots. Calcium levels were higher in plants from alkaline spoils, and manganese levels were higher in plants from acidic mined plots. Manganese levels exceeded 600 ppm in some plant samples from acidic spoil banks. Even when plants from stripped plots contained significantly less of a given element, levels were generally not low enough to indicate nutrient deficiency
Cluster Ellipticities as a Cosmological Probe
We investigate the dependence of ellipticities of clusters of galaxies on
cosmological parameters using large-scale cosmological simulations. We
determine cluster ellipticities out to redshift unity for LCDM models with
different mean densities and amplitudes of mass fluctuation
. The mean ellipticity increases monotonically with redshift for
all models. Larger values of , i.e., earlier cluster formation
time, produce lower ellipticities. The dependence of ellipticity on
is relatively weak in the range for high mass
clusters. The mean ellipticity decreases linearly with the
amplitude of fluctuations at the cluster redshift , nearly independent of
; on average, older clusters are more relaxed and are thus less
elliptical. The distribution of ellipticities about the mean is approximated by
a Gaussian, allowing a simple characterization of the evolution of ellipticity
with redshift as a function of cosmological parameters. At , the mean
ellipticity of high mass clusters is approximated by . This relation opens up the
possibility that, when compared with future observations of large cluster
samples, the mean cluster ellipticity and its evolution could be used as a new,
independent tool to constrain cosmological parameters, especially the amplitude
of mass fluctuations, .Comment: 16 pages, 4 figure
Simultaneous X-ray and radio observations of Young Stellar Objects in NGC 1333 and IC 348
Young Stellar Objects (YSOs) and in particular protostars are known to show a
variety of high-energy processes. Observations in the X-ray and centimetric
radio wavelength ranges are thought to constrain some of these processes, e.g.,
coronal-type magnetic activity. There is a well-known empirical correlation of
radio and X-ray luminosities in active stars, the so-called Guedel-Benz
relation. Previous evidence whether YSOs are compatible with this relation
remains inconclusive for the earliest evolutionary stages. The main difficulty
is that due to the extreme variability of these sources, simultaneous
observations are essential. Until now, only few YSOs and only a handful of
protostars have been observed simultaneously in the X-ray and radio range. To
expand the sample, we have obtained such observations of two young clusters
rich in protostars, NGC 1333 and IC 348. While the absolute sensitivity is
lower for these regions than for more nearby clusters like CrA, we find that
even in deep continuum observations carried out with the NRAO Very Large Array,
the radio detection fraction for protostars in these clusters is much lower
than the X-ray detection fraction. Very few YSOs are detected in both bands,
and we find the radio and X-ray populations among YSOs to be largely distinct.
We combine these new results with previous simultaneous Chandra and VLA
observations of star-forming regions and find that YSOs with detections in both
bands appear to be offset toward higher radio luminosities for given X-ray
luminosities when compared to the Guedel-Benz relation, although even in this
sensitive dataset most sources are too weak for the radio detections to provide
information on the emission processes. The considerably improved sensitivity of
the Expanded Very Large Array will provide a better census of the YSO radio
population as well as better constraints on the emission mechanisms.Comment: Accepted for publication in Ap
Housing Needs in Rural Communities
This study explored housing in small rural communities in an attempt to understand the available housing stock, perceptions of the need for housing, and perceived barriers to housing development. Data were collected through computer-assisted telephone interviews with key community informants. Interviews included forced-choice as well as open-ended questions. Housing issues are described through the words of community leaders with the goal of understanding communities\u27 needs and constraints. Lower cost housing for both renters and owners and housing options for elderly individuals continue to be areas of need in rural communities
Herschel Observations of the W43 "mini-starburst"
Aims: To explore the infrared and radio properties of one of the closest
Galactic starburst regions. Methods: Images obtained with the Herschel Space
Observatory at wavelengths of 70, 160, 250, 350, and 500 microns using the PACS
and SPIRE arrays are analyzed and compared with radio continuum VLA data and 8
micron images from the Spitzer Space Telescope. The morphology of the
far-infrared emission is combined with radial velocity measurements of
millimeter and centimeter wavelength transitions to identify features likely to
be associated with the W43 complex. Results: The W43 star-forming complex is
resolved into a dense cluster of protostars, infrared dark clouds, and ridges
of warm dust heated by massive stars. The 4 brightest compact sources with L >
1.5 x 10^4 Lsun embedded within the Z-shaped ridge of bright dust emission in
W43 remain single at 4" (0.1 pc) resolution. These objects, likely to be
massive protostars or compact clusters in early stages of evolution are
embedded in clumps with masses of 10^3 to 10^4 Msun, but contribute only 2% to
the 3.6 x 10^6 Lsun far-IR luminosity of W43 measured in a 16 by 16 pc box. The
total mass of gas derived from the far-IR dust emission inside this region is
~10^6 Msun. Cometary dust clouds, compact 6 cm radio sources, and warm dust
mark the locations of older populations of massive stars. Energy release has
created a cavity blowing-out below the Galactic plane. Compression of molecular
gas in the plane by the older HII region near G30.684-0.260 and the bipolar
structure of the resulting younger W43 HII region may have triggered the
current mini-star burst.Comment: 5 pages, 3 figures, accepted for A&A Special Issu
The Detection and Characterization of cm Radio Continuum Emission from the Low-mass Protostar L1014-IRS
Observations by the Cores to Disk Legacy Team with the Spitzer Space
Telescope have identified a low luminosity, mid-infrared source within the
dense core, Lynds 1014, which was previously thought to harbor no internal
source. Followup near-infrared and submillimeter interferometric observations
have confirmed the protostellar nature of this source by detecting scattered
light from an outflow cavity and a weak molecular outflow. In this paper, we
report the detection of cm continuum emission with the VLA. The emission is
characterized by a quiescent, unresolved 90 uJy 6 cm source within 0.2" of the
Spitzer source. The spectral index of the quiescent component is between 6 cm and 3.6 cm. A factor of two increase in 6 cm
emission was detected during one epoch and circular polarization was marginally
detected at the level with Stokes {V/I} % . We have
searched for 22 GHz H2O maser emission toward L1014-IRS, but no masers were
detected during 7 epochs of observations between June 2004 and December 2006.
L1014-IRS appears to be a low-mass, accreting protostar which exhibits cm
emission from a thermal jet or a wind, with a variable non-thermal emission
component. The quiescent cm radio emission is noticeably above the correlation
of 3.6 cm and 6 cm luminosity versus bolometric luminosity, indicating more
radio emission than expected. We characterize the cm continuum emission in
terms of observations of other low-mass protostars, including updated
correlations of centimeter continuum emission with bolometric luminosity and
outflow force, and discuss the implications of recent larger distance estimates
on the physical attributes of the protostar and dense molecular core.Comment: 14 pages. Accepted for publication in Ap
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples
We explore the cosmological implications of the angle-averaged correlation function, ξ(s), and the clustering wedges, ξ⊥(s) and ξ∥(s), of the LOWZ and CMASS galaxy samples from Data Releases 10 and 11 of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation from the standard Λ cold dark matter model. The combination of the information from our clustering measurements with recent data from the cosmic microwave background is sufficient to constrain the curvature of the Universe to Ωk = 0.0010 ± 0.0029, the total neutrino mass to ∑mν < 0.23 eV (95 per cent confidence level), the effective number of relativistic species to Neff = 3.31 ± 0.27 and the dark energy equation of state to wDE = −1.051 ± 0.076. These limits are further improved by adding information from Type Ia supernovae and baryon acoustic oscillations from other samples. In particular, this data set combination is completely consistent with a time-independent dark energy equation of state, in which case we find wDE = −1.024 ± 0.052. We explore the constraints on the growth rate of cosmic structures assuming f(z) = Ωm(z)γ and obtain γ = 0.69 ± 0.15, consistent with the predictions of general relativity of γ = 0.55.Publisher PDFPeer reviewe
Ameliorating Systematic Uncertainties in the Angular Clustering of Galaxies: A Study using SDSS-III
We investigate the effects of potential sources of systematic error on the
angular and photometric redshift, z_phot, distributions of a sample of redshift
0.4 < z < 0.7 massive galaxies whose selection matches that of the Baryon
Oscillation Spectroscopic Survey (BOSS) constant mass sample. Utilizing over
112,778 BOSS spectra as a training sample, we produce a photometric redshift
catalog for the galaxies in the SDSS DR8 imaging area that, after masking,
covers nearly one quarter of the sky (9,913 square degrees). We investigate
fluctuations in the number density of objects in this sample as a function of
Galactic extinction, seeing, stellar density, sky background, airmass,
photometric offset, and North/South Galactic hemisphere. We find that the
presence of stars of comparable magnitudes to our galaxies (which are not
traditionally masked) effectively remove area. Failing to correct for such
stars can produce systematic errors on the measured angular auto-correlation
function, w, that are larger than its statistical uncertainty. We describe how
one can effectively mask for the presence of the stars, without removing any
galaxies from the sample, and minimize the systematic error. Additionally, we
apply two separate methods that can be used to correct the systematic errors
imparted by any parameter that can be turned into a map on the sky. We find
that failing to properly account for varying sky background introduces a
systematic error on w. We measure w, in four z_phot slices of width 0.05
between 0.45 < z_phot < 0.65 and find that the measurements, after correcting
for the systematic effects of stars and sky background, are generally
consistent with a generic LambdaCDM model, at scales up to 60 degrees. At
scales greater than 3 degrees and z_phot > 0.5, the magnitude of the
corrections we apply are greater than the statistical uncertainty in w.Comment: Accepted by MNRA
The SDSS-III Baryon Oscillation Spectroscopic Survey: Quasar Target Selection for Data Release Nine
The SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), a five-year
spectroscopic survey of 10,000 deg^2, achieved first light in late 2009. One of
the key goals of BOSS is to measure the signature of baryon acoustic
oscillations in the distribution of Ly-alpha absorption from the spectra of a
sample of ~150,000 z>2.2 quasars. Along with measuring the angular diameter
distance at z\approx2.5, BOSS will provide the first direct measurement of the
expansion rate of the Universe at z > 2. One of the biggest challenges in
achieving this goal is an efficient target selection algorithm for quasars over
2.2 < z < 3.5, where their colors overlap those of stars. During the first year
of the BOSS survey, quasar target selection methods were developed and tested
to meet the requirement of delivering at least 15 quasars deg^-2 in this
redshift range, out of 40 targets deg^-2. To achieve these surface densities,
the magnitude limit of the quasar targets was set at g <= 22.0 or r<=21.85.
While detection of the BAO signature in the Ly-alpha absorption in quasar
spectra does not require a uniform target selection, many other astrophysical
studies do. We therefore defined a uniformly-selected subsample of 20 targets
deg^-2, for which the selection efficiency is just over 50%. This "CORE"
subsample will be fixed for Years Two through Five of the survey. In this paper
we describe the evolution and implementation of the BOSS quasar target
selection algorithms during the first two years of BOSS operations. We analyze
the spectra obtained during the first year. 11,263 new z>2.2 quasars were
spectroscopically confirmed by BOSS. Our current algorithms select an average
of 15 z > 2.2 quasars deg^-2 from 40 targets deg^-2 using single-epoch SDSS
imaging. Multi-epoch optical data and data at other wavelengths can further
improve the efficiency and completeness of BOSS quasar target selection.
[Abridged]Comment: 33 pages, 26 figures, 12 tables and a whole bunch of quasars.
Submitted to Ap
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