26,118 research outputs found
ELEMENTS OF CATTLE FEEDING PROFITABILITY IN MIDWEST FEEDLOTS
Conventional wisdom and earlier research have concluded that cattle feeding profitability is more determined by feeder and fed cattle prices than by animal performance. This study examined cross-sectional and time-series data from over 1600 pens of cattle in more than 220 feedlots in the upper Midwest where weather and lot conditions are thought to influence feedlot profitability. In addition to input and output prices and animal performance, other factors found to significantly impact cattle feeding profitability were sex, placement weight, facility design, and to a lesser extent placement season.cattle feedlots, probability, risk, Livestock Production/Industries,
Propagation of the 2012 March Coronal Mass Ejections from the Sun to Heliopause
In 2012 March the Sun exhibited extraordinary activities. In particular, the
active region NOAA AR 11429 emitted a series of large coronal mass ejections
(CMEs) which were imaged by STEREO as it rotated with the Sun from the east to
west. These sustained eruptions are expected to generate a global shell of
disturbed material sweeping through the heliosphere. A cluster of shocks and
interplanetary CMEs (ICMEs) were observed near the Earth, and are propagated
outward from 1 AU using an MHD model. The transient streams interact with each
other, which erases memory of the source and results in a large merged
interaction region (MIR) with a preceding shock. The MHD model predicts that
the shock and MIR would reach 120 AU around 2013 April 22, which agrees well
with the period of radio emissions and the time of a transient disturbance in
galactic cosmic rays detected by Voyager 1. These results are important for
understanding the "fate" of CMEs in the outer heliosphere and provide
confidence that the heliopause is located around 120 AU from the Sun.Comment: 13 pages, 5 figures, accepted for publication in ApJ Letter
On Sun-to-Earth Propagation of Coronal Mass Ejections: 2. Slow Events and Comparison with Others
As a follow-up study on Sun-to-Earth propagation of fast coronal mass
ejections (CMEs), we examine the Sun-to-Earth characteristics of slow CMEs
combining heliospheric imaging and in situ observations. Three events of
particular interest, the 2010 June 16, 2011 March 25 and 2012 September 25
CMEs, are selected for this study. We compare slow CMEs with fast and
intermediate-speed events, and obtain key results complementing the attempt of
\citet{liu13} to create a general picture of CME Sun-to-Earth propagation: (1)
the Sun-to-Earth propagation of a typical slow CME can be approximately
described by two phases, a gradual acceleration out to about 20-30 solar radii,
followed by a nearly invariant speed around the average solar wind level, (2)
comparison between different types of CMEs indicates that faster CMEs tend to
accelerate and decelerate more rapidly and have shorter cessation distances for
the acceleration and deceleration, (3) both intermediate-speed and slow CMEs
would have a speed comparable to the average solar wind level before reaching 1
AU, (4) slow CMEs have a high potential to interact with other solar wind
structures in the Sun-Earth space due to their slow motion, providing critical
ingredients to enhance space weather, and (5) the slow CMEs studied here lack
strong magnetic fields at the Earth but tend to preserve a flux-rope structure
with axis generally perpendicular to the radial direction from the Sun. We also
suggest a "best" strategy for the application of a triangulation concept in
determining CME Sun-to-Earth kinematics, which helps to clarify confusions
about CME geometry assumptions in the triangulation and to improve CME analysis
and observations.Comment: 37 pages, 13 figures, accepted for publication in ApJ Supplemen
Smoothing dynamic positron emission tomography time courses using functional principal components
A functional smoothing approach to the analysis of PET time course data is presented. By borrowing information across space and accounting for this pooling through the use of a nonparametric covariate adjustment, it is possible to smooth the PET time course data thus reducing the noise. A new model for functional data analysis, the Multiplicative Nonparametric Random Effects Model, is introduced to more accurately account for the variation in the data. A locally adaptive bandwidth choice helps to determine the correct amount of smoothing at each time point. This preprocessing step to smooth the data then allows Subsequent analysis by methods Such as Spectral Analysis to be substantially improved in terms of their mean squared error
Joint vector magnetograph observations at BBSO, Huairou Station and Mees Solar Observatory
Joint vector magnetograph observations were carried out at Big Bear Solar Observatory (BBSO), Huairou Solar Observing Station (Huairou), and Mees Solar Observatory (MSO) in late September 1989. Comparisons of vector magnetograms obtained at the three stations show a high degree of consistency in the morphology of both longitudinal and transverse fields. Quantitative comparisons show the presence of noise, cross-talk between longitudinal field and transverse field, Faraday rotation and signal saturation effects in the magnetograms. We have tried to establish how the scatter in measurements from different instruments is apportioned between these sources of error
Abell 2111: An Optical and Radio Study of the Richest Butcher-Oemler Cluster
We present an in-depth analysis of the Butcher-Oemler cluster A2111,
including new optical spectroscopy plus a deep Very Large Array (VLA) radio
continuum observation. These are combined with optical imaging from the Sloan
Digital Sky Survey (SDSS) to assess the activity and properties of member
galaxies. Prior X-ray studies have suggested A2111 is a head-on cluster merger,
a dynamical state which might be connected to the high level of activity
inferred from its blue fraction. We are able to directly assess this claim,
using our spectroscopic data to identify 95 cluster members among 196 total
galaxy spectra. These galaxy velocities do not themselves provide significant
evidence for the merger interpretation, however they are consistent with it
provided the system is viewed near the time of core passage and at a viewing
angle >~30 degrees different from the merger axis. The SDSS data allow us to
confirm the high blue fraction for A2111, f_b = 0.15 +/- 0.03 based on
photometry alone and f_b = 0.23 +/- 0.03 using spectroscopic data to remove
background galaxies. We are able to detect 175 optical sources from the SDSS in
our VLA radio data, of which 35 have redshift information. We use the SDSS
photometry to determine photometric redshifts for the remaining 140
radio-optical sources. In total we identify up to 26 cluster radio galaxies, 14
of which have spectroscopic redshifts. The optical spectroscopy and radio data
reveal a substantial population of dusty starbursts within the cluster. The
high blue fraction and prevalence of star formation is consistent with the
hypothesis that dynamically-active clusters are associated with more active
member galaxies than relaxed clusters.Comment: To appear in AJ; 53 pages including 10 figures and several long
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