1,833 research outputs found
Recent Outbursts from the Transient X-Ray Pulsar Cep X-4 (GS 2138+56)
We report on X-ray observations of the 66 s period transient X-ray pulsar Cep
X-4 (GS 2138+56) with the Burst and Transient Source Experiment (BATSE) on the
Compton Gamma-Ray Observatory (CGRO) and with the Rossi X-ray Timing Explorer
(RXTE). Two outbursts from Cep X-4 were observed with BATSE in 1993 June-July
and 1997 July. Pulse frequencies of 15.0941 +/- 0.0002 mHz on 1993 June 25 (MJD
49,163) and 15.0882 +/- 0.0002 mHz on 1997 July 12 (MJD 50,641) were each
measured from 2 day spans of BATSE data near each outburst's peak. Cep X-4
showed an average spin down rate of (-4.14 +/- 0.08)*10^(-14) Hz/s between the
1993 and 1997 outbursts. After BATSE could no longer detect Cep X-4, public
observations were performed on 1997 July 18 & 25 with the Proportional Counter
Array (PCA) on RXTE. A pulse frequency of 15.088 +/- 0.004 mHz was measured
from observations on 1997 July 18 (MJD 50,647). Significant aperiodic noise,
with an rms variance of ~18% in the frequency range 0.01-1.0 Hz was observed on
both days. Energy and intensity dependent pulse shape variations were also seen
in these data. Recently published optical observations associate Cep X-4 with a
Be companion star. If all 4 outbursts observed from Cep X-4 are assumed to
occur at the same orbital phase, we find that the orbital period is between 23
days and 147.3 days.Comment: 19 pages (LaTeX) including 9 figures. Accepted for publication in the
Astrophysical Journa
Preliminary Feeding Assessments for Asiatic Garden Beetle, Maladera formosae (Coleoptera: Scarabaeidae), Grubs and Adults
The Asiatic garden beetle, Maladera formosae (Brenske) (syn. M. castanea [Arrow]), is an annual white grub species that was unintentionally introduced from east Asia to North America in 1921 in New Jersey, and has since spread to at least 25 states and two Canadian provinces. Grub populations in the Great Lakes region have recently emerged as significant early-season pests of field crops, particularly field corn, grown in sandy soils. Asiatic garden beetle has also recently become established in other regions including Alabama. Prior research on this species was conducted mainly in the 1930s in horticultural and turfgrass systems of New York and New Jersey. In this study, we document Asiatic garden beetle preference and performance on previously un-investigated food resources, in populations from Ohio and Alabama. The objectives of these experiments were to a) understand if grubs show preference to potential diet choices present in a typical Ohio corn-soybean rotation, and gained mass when provided a single diet, and b) to conduct a preliminary assessment on the development, survival, and fecundity of field-collected beetles on different diets present in suburban Alabama. In general, grubs were more likely to be found at corn and marestail and they significantly increased in body mass when subjected to those diets. However, they were also able to survive and gain mass when provided soybean, crop residues or bare soil. Adults consumed more rose flower petals than floral tissue of white clover and Queen Anne’s lace. In no-choice trials, only females that were fed a diet of rose petals laid eggs, and diet consumption rates were similar among males and females. These findings provide insight into the feeding behaviors of Asiatic garden beetle grubs and adults collected from novel environments
Public Health Governance and Population Health Outcomes
Research reviews have identified a gap in understanding the diversity of health department governance structures and in understanding how the variations in governing relates to health outcomes. This report details the categorization of local public health governance and reveals that certain governance types may be better suited to achieve better population health outcomes. State systems achieve the poorest health outcomes, but the best health outcomes are achieved when the political branches have a key role in local public health governance. Public health systems should consider greater local control and involvement in governance; but local governance should include the political branches -- and even the state -- to achieve more positive health outcomes
Cerium-Based Spontaneous Coating Process for Corrosion Protection of Aluminum Alloys
A cerium-based coating for corrosion resistance is applied by exposing a cleaned aluminum-based component to a corrosion-inhibiting cerium solution containing cerium ions in the presence of an oxidizing agent. The coating deposits spontaneously without an external source of electrons
RXTE Observations of the Anomalous Pulsar 4U 0142+61
We observed the anomalous X-ray pulsar 4U 0142+61 using the Proportional
Counter Array (PCA) aboard the Rossi X-ray Timing Explorer (RXTE) in March
1996. The pulse frequency was measured as f = 0.11510039(3) Hz with an upper
limit of df/dt < 4 * 10^(-13) Hz/s upon the short term change in frequency over
the 4.6 day span of the observations. A compilation of all historical
measurements showed an overall spin-down trend with slope df/dt = (-3.0 +/-
0.1) * 10^(-14) Hz/s. Searches for orbital modulations in pulse arrival times
yielded an upper limit of a_x sin i < 0.26 lt-s (99% confidence) for the period
range 70 s to 2.5 days. These limits combined with previous optical limits and
evolutionary arguments suggest that 4U 0142+61 is probably not a member of a
binary system.Comment: 20 pages (LaTeX) including 7 figures. Accepted for publication in the
Astrophysical Journa
BLAST Observations of the South Ecliptic Pole field: Number Counts and Source Catalogs
We present results from a survey carried out by the Balloon-borne Large
Aperture Submillimeter Telescope (BLAST) on a 9 deg^2 field near the South
Ecliptic Pole at 250, 350 and 500 {\mu}m. The median 1{\sigma} depths of the
maps are 36.0, 26.4 and 18.4 mJy, respectively. We apply a statistical method
to estimate submillimeter galaxy number counts and find that they are in
agreement with other measurements made with the same instrument and with the
more recent results from Herschel/SPIRE. Thanks to the large field observed,
the new measurements give additional constraints on the bright end of the
counts. We identify 132, 89 and 61 sources with S/N>4 at 250, 350, 500 {\mu}m,
respectively and provide a multi-wavelength combined catalog of 232 sources
with a significance >4{\sigma} in at least one BLAST band. The new BLAST maps
and catalogs are available publicly at http://blastexperiment.info.Comment: 25 pages, 6 figures, 4 tables, Accepted by ApJS. Maps and catalogs
available at http://blastexperiment.info
Use of small animal PET-CT imaging for in vivo assessment of tendon-to-bone healing: A pilot study.
BACKGROUND
The availability of non-invasive means to evaluate and monitor tendon-bone healing processes in-vivo is limited. Micro Positron-Emission-Tomography (µPET) using 18F-Fluoride is a minimally invasive imaging modality, with which osteoblast activity and bone turnover can be assessed. The aim of this study was to investigate the use of serial in-vivo µPET/CT scans to evaluate bone turnover along the graft-tunnel interface in a rat ACL (anterior cruciate ligament) reconstruction model.
METHODS
Unilateral autograft ACL reconstruction was performed in six rats. µPET/CT-scans using 18F-Fluoride were performed 7, 14, 21, and 28 days postoperatively. Standard uptake values (SUV) were calculated for three tunnel regions (intraarticular aperture (IAA), mid-tunnel, and extraarticular aperture (EAA)) of the proximal tibia. Animals were sacrificed at 28 days and evaluated with µCT and histological analysis.
RESULTS
SUVs in both bone tunnels showed an increased 18F-Fluoride uptake at 7Â days when compared to 14, 21, and 28Â days. SUVs showed a gradient on the tibial side, with most bone turnover in the IAA and least in the EAA. At 7, 14, 21, and 28Â days, there were significantly higher SUV values in the IAA compared to the EAA (p = .01, < .01, < .01, < .01). SUVs positively correlated with new bone volumetric density obtained with ÎĽCT (r = 0.449, p = .013). Volumetric density of newly formed bone detected on ÎĽCT correlated with osteoblast numbers observed along the tunnels in histological sections (r = 0.452, p < .016).
CONCLUSIONS
Serial in-vivo µPET/CT-scanning has the potential to provide insight into bone turnover and therefore osteoblastic activity during the healing process. As a result, it allows us to directly measure the effect of interventional strategies in tendon-bone healing
Detecting the Companions and Ellipsoidal Variations of RS CVn Primaries: II. omicron Draconis, a Candidate for Recent Low-Mass Companion Ingestion
To measure the stellar and orbital properties of the metal-poor RS CVn binary
o Draconis (o Dra), we directly detect the companion using interferometric
observations obtained with the Michigan InfraRed Combiner at Georgia State
University's Center for High Angular Resolution Astronomy (CHARA) Array. The
H-band flux ratio between the primary and secondary stars is the highest
confirmed flux ratio (370 +/- 40) observed with long-baseline optical
interferometry. These detections are combined with radial velocity data of both
the primary and secondary stars, including new data obtained with the
Tillinghast Reflector Echelle Spectrograph on the Tillinghast Reflector at the
Fred Lawrence Whipple Observatory and the 2-m Tennessee State University
Automated Spectroscopic Telescope at Fairborn Observatory. We determine an
orbit from which we find model-independent masses and ages of the components
(M_A = 1.35 +\- 0.05 M_Sun, M_B = 0.99 +\- 0.02 M_Sun, system age = 3.0 -\+ 0.5
Gyr). An average of a 23-year light curve of o Dra from the Tennessee State
University Automated Photometric Telescope folded over the orbital period newly
reveals eclipses and the quasi-sinusoidal signature of ellipsoidal variations.
The modeled light curve for our system's stellar and orbital parameters confirm
these ellipsoidal variations due to the primary star partially filling its
Roche lobe potential, suggesting most of the photometric variations are not due
to stellar activity (starspots). Measuring gravity darkening from the average
light curve gives a best-fit of beta = 0.07 +\- 0.03, a value consistent with
conventional theory for convective envelope stars. The primary star also
exhibits an anomalously short rotation period, which, when taken with other
system parameters, suggests the star likely engulfed a low-mass companion that
had recently spun-up the star.Comment: 14 pages, 13 figures, Accepted to Ap
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