3,382 research outputs found
The Mission Accessible Near-Earth Objects Survey: Four years of photometry
Over 4.5 years, the Mission Accessible Near-Earth Object Survey (MANOS)
assembled 228 Near-Earth Object (NEO) lightcurves. We report rotational
lightcurves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs,
lightcurves with no detected variability within the image signal to noise and
length of our observing block for 30 NEOs, and 10 tumblers. We uncovered 2
ultra-rapid rotators with periods below 20s; 2016MA with a potential rotational
periodicity of 18.4s, and 2017QG rotating in 11.9s, and estimate the
fraction of fast/ultra-rapid rotators undetected in our project plus the
percentage of NEOs with a moderate/long periodicity undetectable during our
typical observing blocks. We summarize the findings of a simple model of
synthetic NEOs to infer the object morphologies distribution using the measured
distribution of lightcurve amplitudes. This model suggests a uniform
distribution of axis ratio can reproduce the observed sample. This suggests
that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the
quantity of highly elongated objects (e.g., Itokawa), a result that can be
directly tested thanks to shape models from Doppler delay radar imaging
analysis. Finally, we fully characterized 2 NEOs as appropriate targets for a
potential robotic/human mission: 2013YS and 2014FA due to their
moderate spin periods and low .Comment: Accepted for Publication, The Astrophysical Journal Supplement Serie
Kepler Input Catalog: Photometric Calibration and Stellar Classification
We describe the photometric calibration and stellar classification methods
used to produce the Kepler Input Catalog (KIC). The KIC is a catalog containing
photometric and physical data for sources in the Kepler Mission field of view;
it is used by the mission to select optimal targets. We derived atmospheric
extinction corrections from hourly observations of secondary standard fields
within the Kepler field of view. Repeatability of absolute photometry for stars
brighter than magnitude 15 is typically 2%. We estimated stellar parameters
Teff, log(g), log (Z), E_{B-V} using Bayesian posterior probability
maximization to match observed colors to Castelli stellar atmosphere models. We
applied Bayesian priors describing the distribution of solar-neighborhood stars
in the color-magnitude diagram (CMD), in log (Z)$, and in height above the
galactic plane. Comparisons with samples of stars classified by other means
indicate that in most regions of the CMD, our classifications are reliable
within about +/- 200 K and +/- 0.4 dex in log (g). It is difficult to assess
the reliability of our log(Z) estimates, but there is reason to suspect that it
is poor, particularly at extreme Teff. Of great importance for the Kepler
Mission, for Teff <= 5400 K, the distinction between main-sequence stars and
giants has proved to be reliable with better than 98% confidence. The KIC is
available through the MAST data archive.Comment: 77 pages, 12 figures, 1 Table. Accepted by Astronomical Journal 24
July 201
MANURE MANAGEMENT FOR WATER QUALITY COSTS TO ANIMAL FEEDING OPERATIONS OF APPLYING MANURE NUTRIENTS TO LAND
Nutrients from livestock and poultry manure are key sources of water pollution. Ever-growing numbers of animals per farm and per acre have increased the risk of water pollution. New Clean Water Act regulations compel the largest confined animal producers to meet nutrient application standards when applying manure to the land, and USDA encourages all animal feeding operations to do the same. The additional costs for managing manure (such as hauling manure off the farm) have implications for feedgrain producers and consumers as well. This report's farm-level analysis examines on-farm technical choice and producer costs across major U.S. production areas for hauling manure to the minimum amount of land needed to assimilate manure nutrients. A regional analysis then focuses on off-farm competition for land to spread surplus manure, using the Chesapeake Bay region as a case study. Finally, a sectorwide analysis addresses potential long-term structural adjustments at the national level and ultimate costs to consumers and producers.manure management costs, price and quantity adjustments, water quality, animal waste, manure nutrients, excess nutrients, confined animals, CAFO, manure nitrogen, manure phosphorus, manure use, assimilative capacity, nutrient management plan, Environmental Economics and Policy, Livestock Production/Industries,
A habitat-use model to determine essential fish habitat for juvenile brown shrimp (Farfantepenaeus aztecus) in Galveston Bay, Texas
A density prediction model for juvenile brown shrimp (Farfantepenaeus aztecus) was developed by using three bottom types, five salinity zones, and four seasons to quantify patterns of habitat use in Galveston Bay, Texas. Sixteen years of quantitative density data were used. Bottom types were vegetated marsh edge, submerged aquatic vegetation, and shallow nonvegetated bottom. Multiple regression was used to develop density estimates, and the resultant formula was then coupled with a geographical information system (GIS) to provide a spatial mosaic (map) of predicted habitat use. Results indicated that juvenile brown shrimp (0.50. These results indicate that this model may have a broader geographic application and is a plausible approach in refining current EFH designations for all Gulf of Mexico estuaries with similar geomorphological and hydrological characteristics
Detection of CI in absorption towards PKS 1830-211 with the eSMA
We report the first science observations and results obtained with the
"extended" SMA (eSMA), which is composed of the SMA (Submillimeter Array), JCMT
(James Clerk Maxwell Telescope) and CSO (Caltech Submillimeter Observatory).
Redshifted absorptions at z=0.886 of CI (^3P_1 - ^3P_0) were observed with the
eSMA with an angular resolution of 0.55"x0.22" at 1.1 mm toward the
southwestern image of the remarkable lensed quasar PKS 1830-211, but not toward
the northeastern component at a separation of ~1". Additionally, SMA
observations of CO, 13CO and C18O (all J=4-3) were obtained toward this object:
CO was also detected toward the SW component, but none of the isotopologues
were. This is the first time [CI] is detected in this object, allowing the
first direct determination of relative abundances of neutral atomic carbon to
CO in the molecular clouds of a spiral galaxy at z>0.1. The [CI] and CO
profiles can be decomposed into two and three velocity components respectively.
We derive C/CO column density ratios ranging from <0.5 (representative of dense
cores) to ~2.5 (close to translucent clouds values). This could indicate that
we are seeing environments with different physical conditions or that we are
witnessing chemical evolution of regions where C has not completely been
converted into CO.Comment: 6 pages using emulateapj, 3 tables, 2 figures ; accepted for
publication in ApJ
The eSMA: description and first results
The eSMA ("extended SMA") combines the SMA, JCMT and CSO into a single
facility, providing enhanced sensitivity and spatial resolution owing to the
increased collecting area at the longest baselines. Until ALMA early science
observing (2011), the eSMA will be the facility capable of the highest angular
resolution observations at 345 GHz. The gain in sensitivity and resolution will
bring new insights in a variety of fields, such as protoplanetary/transition
disks, high-mass star formation, solar system bodies, nearby and high-z
galaxies. Therefore the eSMA is an important facility to prepare the grounds
for ALMA and train scientists in the techniques.
Over the last two years, and especially since November 2006, there has been
substantial progress toward making the eSMA into a working interferometer. In
particular, (i) new 345-GHz receivers, that match the capabilities of the SMA
system, were installed at the JCMT and CSO; (ii) numerous tests have been
performed for receiver, correlator and baseline calibrations in order to
determine and take into account the effects arising from the differences
between the three types of antennas; (iii) first fringes at 345 GHz were
obtained on August 30 2007, and the array has entered the science-verification
stage.
We report on the characteristics of the eSMA and its measured performance at
230 GHz and that expected at 345 GHz. We also present the results of the
commissioning and some initial science-verification observations, including the
first absorption measurement of the C/CO ratio in a galaxy at z=0.89, located
along the line of sight to the lensed quasar PKS1830-211, and on the imaging of
the vibrationally excited HCN line towards IRC+10216.Comment: 12 pages, 7 figures, paper number 7012-12, to appear in Proceedings
of SPIE vol. 7012: "Ground-based and Airborne Telescopes II", SPIE conference
on Astronomical Instrumentation, Marseille, 23-28 June 200
Kepler-432: a red giant interacting with one of its two long period giant planets
We report the discovery of Kepler-432b, a giant planet ()
transiting an evolved star with an orbital period of days. Radial velocities (RVs) reveal that
Kepler-432b orbits its parent star with an eccentricity of , which we also measure independently with
asterodensity profiling (AP; ), thereby confirming
the validity of AP on this particular evolved star. The well-determined
planetary properties and unusually large mass also make this planet an
important benchmark for theoretical models of super-Jupiter formation.
Long-term RV monitoring detected the presence of a non-transiting outer planet
(Kepler-432c; days), and adaptive optics imaging revealed a nearby
(0\farcs87), faint companion (Kepler-432B) that is a physically bound M dwarf.
The host star exhibits high signal-to-noise asteroseismic oscillations, which
enable precise measurements of the stellar mass, radius and age. Analysis of
the rotational splitting of the oscillation modes additionally reveals the
stellar spin axis to be nearly edge-on, which suggests that the stellar spin is
likely well-aligned with the orbit of the transiting planet. Despite its long
period, the obliquity of the 52.5-day orbit may have been shaped by star-planet
interaction in a manner similar to hot Jupiter systems, and we present
observational and theoretical evidence to support this scenario. Finally, as a
short-period outlier among giant planets orbiting giant stars, study of
Kepler-432b may help explain the distribution of massive planets orbiting giant
stars interior to 1 AU.Comment: 22 pages, 19 figures, 5 tables. Accepted to ApJ on Jan 24, 2015
(submitted Nov 11, 2014). Updated with minor changes to match published
versio
Regulation of virulence gene expression resulting from Streptococcus pneumoniae and nontypeable Haemophilus influenzae interactions in chronic disease
Chronic rhinosinusitis (CRS) is a common inflammatory disease of the sinonasal cavity mediated, in part, by polymicrobial communities of bacteria. Recent molecular studies have confirmed the importance of Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) in CRS. Here, we hypothesize that interaction between S. pneumoniae and NTHi mixed-species communities cause a change in bacterial virulence gene expression. We examined CRS as a model human disease to validate these polymicrobial interactions. Clinical strains of S. pneumoniae and NTHi were grown in mono- and coculture in a standard biofilm assay. Reverse transcriptase real-time PCR (RTqPCR) was used to measure gene expression of key virulence factors. To validate these results, we investigated the presence of the bacterial RNA transcripts in excised human tissue from patients with CRS. Consequences of physical or chemical interactions between microbes were also investigated. Transcription of NTHi type IV pili was only expressed in co-culture in vitro, and expression could be detected ex vivo in diseased tissue. S. pneumoniae pyruvate oxidase was up-regulated in co-culture, while pneumolysin and pneumococcal adherence factor A were down-regulated. These results were confirmed in excised human CRS tissue. Gene expression was differentially regulated by physical contact and secreted factors. Overall, these data suggest that interactions between H. influenzae and S. pneumoniae involve physical and chemical mechanisms that influence virulence gene expression of mixed-species biofilm communities present in chronically diseased human tissue. These results extend previous studies of population-level virulence and provide novel insight into the importance of S. pneumoniae and NTHi in CRS
TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
Data from the newly-commissioned \textit{Transiting Exoplanet Survey
Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf
located 15 pc away. The planet has a radius of and
orbits the star every 11 hours. Although the existence of an atmosphere around
such a strongly irradiated planet is questionable, the star is bright enough
(, ) for this possibility to be investigated with transit and
occultation spectroscopy. The star's brightness and the planet's short period
will also facilitate the measurement of the planet's mass through Doppler
spectroscopy.Comment: 10 pages, 4 figures. Submitted to ApJ Letters. This letter makes use
of the TESS Alert data, which is currently in a beta test phase, using data
from the pipelines at the TESS Science Office and at the TESS Science
Processing Operations Cente
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