729 research outputs found
An unexpected diagnosis of methicillin-resistant Staphylococcus aureus septic arthritis
Hand infections can result in serious tissue damage and gross functional impairment. This is particularly true in the case of septic arthritis, the most destructive of all joint disease. We report the first case of methicillin-resistant Staphylococcus aureus septic arthritis of the distal interphalangeal joint to have occurred in a patient devoid of all risk factors traditionally associated with a hospital-associated infection (HA-MRSA). The afflicted patient's only exposure to the pathogen was during her role as a community carer for an asymptomatic carrier. Delayed treatment allowed the infection to rapidly destroy surrounding soft tissue and necessitate in the need for arthrodesis. It is, therefore imperative that clinicians maintain a low index of suspicion for methicillin-resistant Staphylococcus aureus as the causative pathogen in similar cases. Consequently, consideration of empirical antibiotic therapy for this patient subgroup is discussed
The Bolocam Galactic Plane Survey. XII. Distance Catalog Expansion Using Kinematic Isolation of Dense Molecular Cloud Structures With 13CO(1-0)
We present an expanded distance catalog for 1,710 molecular cloud structures
identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing
a nearly threefold increase over the previous BGPS distance catalog. We
additionally present a new method for incorporating extant data sets into our
Bayesian distance probability density function (DPDF) methodology. To augment
the dense-gas tracers (e.g., HCO+(3-2), NH3(1,1)) used to derive line-of-sight
velocities for kinematic distances, we utilize the Galactic Ring Survey
13CO(1-0) data to morphologically extract velocities for BGPS sources. The
outline of a BGPS source is used to select a region of the GRS 13CO data, along
with a reference region to subtract enveloping diffuse emission, to produce a
line profile of 13CO matched to the BGPS source. For objects with a HCO+(3-2)
velocity, \approx 95% of the new 13CO(1-0) velocities agree with that of the
dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution,
based on a validated formalism for associating molecular cloud structures with
known objects from the literature, is presented. We demonstrate this prior
using catalogs of masers with trigonometric parallaxes and HII regions with
robust KDA resolutions. The distance catalog presented here contains
well-constrained distance estimates for 20% of BGPS V2 sources, with typical
distance uncertainties \lesssim 0.5 kpc. Approximately 75% of the
well-constrained sources lie within 6 kpc of the Sun, concentrated in the
Scutum-Centarus arm. Galactocentric positions of objects additionally trace out
portions of the Sagittarius, Perseus, and Outer arms in the first and second
Galactic quadrants, and we also find evidence for significant regions of
interarm dense gas.Comment: 28 pages, 19 figures. Accepted for publication in ApJ.
Distance-Omnibus code available at https://github.com/BGPS/distance-omnibu
The Bolocam Galactic Plane Survey. XIII. Physical Properties and Mass Functions of Dense Molecular Cloud Structures
We use the distance probability density function (DPDF) formalism of
Ellsworth-Bowers et al. (2013, 2015) to derive physical properties for the
collection of 1,710 Bolocam Galactic Plane Survey (BGPS) version 2 sources with
well-constrained distance estimates. To account for Malmquist bias, we estimate
that the present sample of BGPS sources is 90% complete above 400 and
50% complete above 70 . The mass distributions for the entire sample
and astrophysically motivated subsets are generally fitted well by a lognormal
function, with approximately power-law distributions at high mass. Power-law
behavior emerges more clearly when the sample population is narrowed in
heliocentric distance (power-law index for sources nearer
than 6.5 kpc and for objects between 2 kpc and 10 kpc).
The high-mass power-law indices are generally for
various subsamples of sources, intermediate between that of giant molecular
clouds and the stellar initial mass function. The fit to the entire sample
yields a high-mass power-law . Physical
properties of BGPS sources are consistent with large molecular cloud clumps or
small molecular clouds, but the fractal nature of the dense interstellar medium
makes difficult the mapping of observational categories to the dominant
physical processes driving the observed structure. The face-on map of the
Galactic disk's mass surface density based on BGPS dense molecular cloud
structures reveals the high-mass star-forming regions W43, W49, and W51 as
prominent mass concentrations in the first quadrant. Furthermore, we present a
0.25-kpc resolution map of the dense gas mass fraction across the Galactic disk
that peaks around 5%.Comment: Accepted for publication in ApJ; 32 pages, 21 figure
The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension
We present a re-reduction and expansion of the Bolocam Galactic Plane Survey,
first presented by Aguirre et al. (2011) and Rosolowsky et al. (2010). The BGPS
is a 1.1 mm survey of dust emission in the Northern galactic plane, covering
longitudes -10 < \ell < 90 and latitudes |b| < 0.5 with a typical 1-\sigma RMS
sensitivity of 30-100 mJy in a 33" beam. Version 2 of the survey includes an
additional 20 square degrees of coverage in the 3rd and 4th quadrants and 2
square degrees in the 1st quadrant. The new data release has improved angular
recovery, with complete recovery out to 80" and partial recovery to 300", and
reduced negative bowls around bright sources resulting from the atmospheric
subtraction process. We resolve the factor of 1.5 flux calibration offset
between the v1.0 data release and other data sets and determine that there is
no offset between v2.0 and other data sets. The v2.0 pointing accuracy is
tested against other surveys and demonstrated to be accurate and an improvement
over v1.0. We present simulations and tests of the pipeline and its properties,
including measurements of the pipeline's angular transfer function. The Bolocat
cataloging tool was used to extract a new catalog, which includes 8594 sources,
with 591 in the expanded regions. We have demonstrated that the Bolocat 40" and
80" apertures are accurate even in the presence of strong extended background
emission. The number of sources is lower than in v1.0, but the amount of flux
and area included in identified sources is larger.Comment: 36 pages, 16 figures, accepted to ApJS. Data available from
http://irsa.ipac.caltech.edu/data/BOLOCAM_GPS
The Bolocam Galactic Plane Survey. XIV. Physical Properties of Massive Starless and Star Forming Clumps
We sort molecular clouds between from the
Bolocam Galactic Plane Survey based on observational diagnostics of star
formation activity: compact sources, mid-IR color-selected
YSOs, and masers, and UCHII regions. We also
present a combined -derived gas kinetic temperature and maser catalog for clumps from our own GBT 100m observations and
from the literature. We identify a subsample of () starless
clump candidates, the largest and most robust sample identified from a blind
survey to date. Distributions of flux density, flux concentration, solid angle,
kinetic temperature, column density, radius, and mass show strong ( dex)
progressions when sorted by star formation indicator. The median starless clump
candidate is marginally sub-virial () with of clumps
with known distance being gravitationally bound (). These samples
show a statistically significant increase in the median clump mass of M from the starless candidates to clumps associated with
protostars. This trend could be due to (i) mass growth of the clumps at
Msun Myr for an average free-fall Myr
time-scale, (ii) a systematic factor of two increase in dust opacity from
starless to protostellar phases, (iii) and/or a variation in the ratio of
starless to protostellar clump lifetime that scales as . By
comparing to the observed number of maser containing clumps we
estimate the phase-lifetime of massive ( M) starless clumps to
be ; the majority
( M) have phase-lifetimes longer than their average free-fall
time.Comment: Accepted for publication in ApJ; 33 pages; 22 figures; 7 table
The Spitzer c2d Survey of Nearby Dense Cores: III: Low Mass Star Formation in a Small Group, L1251B
We present a comprehensive study of a low-mass star-forming region,L1251B, at
wavelengths from the near-infrared to the millimeter. L1251B, where only one
protostar, IRAS 22376+7455, was known previously, is confirmed to be a small
group of protostars based on observations with the Spitzer Space Telescope. The
most luminous source of L1251B is located 5" north of the IRAS position. A
near-infrared bipolar nebula, which is not associated with the brightest object
and is located at the southeast corner of L1251B, has been detected in the IRAC
bands. OVRO and SMA interferometric observations indicate that the brightest
source and the bipolar nebula source in the IRAC bands are deeply embedded disk
sources.Submillimeter continuum observations with single-dish telescopes and
the SMA interferometric observations suggest two possible prestellar objects
with very high column densities. Outside of the small group, many young stellar
object candidates have been detected over a larger region of 12' x 12'.
Extended emission to the east of L1251B has been detected at 850 micron; this
"east core" may be a site for future star formation since no point source has
been detected with IRAC or MIPS. This region is therefore a possible example of
low-mass cluster formation, where a small group of pre- and protostellar
objects (L1251B) is currently forming, alongside a large starless core (the
east core).Comment: 35 pages, 15 figures, accepted for publication in ApJ, for the full
resolution paper, visit
"http://peggysue.as.utexas.edu/SIRTF/PAPERS/pap27.pub.pdf
Computational Ranking of Yerba Mate Small Molecules Based on Their Predicted Contribution to Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus
The aqueous extract of yerba mate, a South American tea beverage made from Ilex paraguariensis leaves, has demonstrated bactericidal and inhibitory activity against bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). The gas chromatography-mass spectrometry (GC-MS) analysis of two unique fractions of yerba mate aqueous extract revealed 8 identifiable small molecules in those fractions with antimicrobial activity. For a more comprehensive analysis, a data analysis pipeline was assembled to prioritize compounds for antimicrobial testing against both MRSA and methicillin-sensitive S.aureus using forty-two unique fractions of the tea extract that were generated in duplicate, assayed for activity, and analyzed with GC-MS. As validation of our automated analysis, we checked our predicted active compounds for activity in literature references and used authentic standards to test for antimicrobial activity. 3,4-dihydroxybenzaldehyde showed the most antibacterial activity against MRSA at low concentrations in our bioassays. In addition, quinic acid and quercetin were identified using random forests analysis and 5-hydroxy pipecolic acid was identified using linear discriminant analysis. We also generated a ranked list of unidentified compounds that may contribute to the antimicrobial activity of yerba mate against MRSA. Here we utilized GC-MS data to implement an automated analysis that resulted in a ranked list of compounds that likely contribute to the antimicrobial activity of aqueous yerba mate extract against MRSA
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