3,146 research outputs found
An Infrared through Radio Study of the Properties and Evolution of IRDC Clumps
We examine the physical properties and evolutionary stages of a sample of 17
clumps within 8 Infrared Dark Clouds (IRDCs) by combining existing infrared,
millimeter, and radio data with new Bolocam Galactic Plane Survey (BGPS) 1.1 mm
data, VLA radio continuum data, and HHT dense gas (HCO+ and N2H+) spectroscopic
data. We combine literature studies of star formation tracers and dust
temperatures within IRDCs with our search for ultra-compact (UC) HII regions to
discuss a possible evolutionary sequence for IRDC clumps. In addition, we
perform an analysis of mass tracers in IRDCs and find that 8 micron extinction
masses and 1.1 mm Bolocam Galactic Plane Survey (BGPS) masses are complementary
mass tracers in IRDCs except for the most active clumps (notably those
containing UCHII regions), for which both mass tracers suffer biases. We find
that the measured virial masses in IRDC clumps are uniformly higher than the
measured dust continuum masses on the scale of ~1 pc. We use 13CO, HCO+, and
N2H+ to study the molecular gas properties of IRDCs and do not see any evidence
of chemical differentiation between hot and cold clumps on the scale of ~1 pc.
However, both HCO+ and N2H+ are brighter in active clumps, due to an increase
in temperature and/or density. We report the identification of four UCHII
regions embedded within IRDC clumps and find that UCHII regions are associated
with bright (>1 Jy) 24 micron point sources, and that the brightest UCHII
regions are associated with "diffuse red clumps" (an extended enhancement at 8
micron). The broad stages of the discussed evolutionary sequence (from a
quiescent clump to an embedded HII region) are supported by literature dust
temperature estimates; however, no sequential nature can be inferred between
the individual star formation tracers.Comment: 33 pages, 26 figures, 6 tables, accepted for publication in ApJ. Full
resolution version available here:
http://casa.colorado.edu/~battersb/Publications.htm
Peat Bog Wildfire Smoke Exposure in Rural North Carolina Is Associated with Cardiopulmonary Emergency Department Visits Assessed through Syndromic Surveillance
Background: In June 2008, burning peat deposits produced haze and air pollution far in excess of National Ambient Air Quality Standards, encroaching on rural communities of eastern North Carolina. Although the association of mortality and morbidity with exposure to urban air pollution is well established, the health effects associated with exposure to wildfire emissions are less well understood.
Objective: We investigated the effects of exposure on cardiorespiratory outcomes in the population affected by the fire.
Methods: We performed a population-based study using emergency department (ED) visits reported through the syndromic surveillance program NC DETECT (North Carolina Disease Event Tracking and Epidemiologic Collection Tool). We used aerosol optical depth measured by a satellite to determine a high-exposure window and distinguish counties most impacted by the dense smoke plume from surrounding referent counties. Poisson log-linear regression with a 5-day distributed lag was used to estimate changes in the cumulative relative risk (RR).
Results: In the exposed counties, significant increases in cumulative RR for asthma [1.65 (95% confidence interval, 1.25–2.1)], chronic obstructive pulmonary disease [1.73 (1.06–2.83)], and pneumonia and acute bronchitis [1.59 (1.07–2.34)] were observed. ED visits associated with cardiopulmonary symptoms [1.23 (1.06–1.43)] and heart failure [1.37 (1.01–1.85)] were also significantly increased.
Conclusions: Satellite data and syndromic surveillance were combined to assess the health impacts of wildfire smoke in rural counties with sparse air-quality monitoring. This is the first study to demonstrate both respiratory and cardiac effects after brief exposure to peat wildfire smoke
Supervising the Supervisors—Procedural Training and Supervision in Internal Medicine Residency
At teaching hospitals, bedside procedures (paracentesis, thoracentesis, lumbar puncture, arthrocentesis and central venous catheter insertion) are performed by junior residents and supervised by senior peers. Residents’ perceptions about supervision or how often peer supervision produces unsafe clinical situations are unknown.
To examine the experience and practice patterns of residents performing bedside procedures.
Cross-sectional e-mail survey of 653 internal medicine (IM) residents at seven California teaching hospitals.
Surveys asked questions in three areas: (1) resident experience performing procedures: numbers of procedures performed and whether they received other (e.g., simulator) training; (2) resident comfort performing and supervising procedures; (3) resident reports of their current level of supervision doing procedures, experience with complications as well as perceptions of factors that may have contributed to complications.
Three hundred sixty-seven (56%) of the residents responded. Most PGY1 residents had performed fewer than five of any of the procedures, but most PGY-3 residents had performed at least ten by the end of their training. Resident comfort for each procedure increased with the number of procedures performed (p < 0.001). Although residents reported that peer supervision happened often, they also reported high rates of supervising a procedure before feeling comfortable with proper technique. The majority of residents (64%) reported at least one complication and did not feel supervision would have prevented complications, even though many reported complications represented technique- or preparation-related problems.
Residents report low levels of comfort and experience with procedures, and frequently report supervising prior to feeling comfortable. Our findings suggest a need to examine best practices for procedural supervision of trainees
The \u3cem\u3eChlamydomonas\u3c/em\u3e Genome Reveals the Evolution of Key Animal and Plant Functions
Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the ∼120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella
UBVRI Light Curves of 44 Type Ia Supernovae
We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from
1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence
Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The
data set comprises 2190 observations and is the largest homogeneously observed
and reduced sample of SN Ia to date, nearly doubling the number of
well-observed, nearby SN Ia with published multicolor CCD light curves. The
large sample of U-band photometry is a unique addition, with important
connections to SN Ia observed at high redshift. The decline rate of SN Ia
U-band light curves correlates well with the decline rate in other bands, as
does the U-B color at maximum light. However, the U-band peak magnitudes show
an increased dispersion relative to other bands even after accounting for
extinction and decline rate, amounting to an additional ~40% intrinsic scatter
compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication
in the Astronomical Journal. Version with high-res figures and electronic
data at http://astron.berkeley.edu/~saurabh/cfa2snIa
Holographic Vitrification
We establish the existence of stable and metastable stationary black hole
bound states at finite temperature and chemical potentials in global and planar
four-dimensional asymptotically anti-de Sitter space. We determine a number of
features of their holographic duals and argue they represent structural
glasses. We map out their thermodynamic landscape in the probe approximation,
and show their relaxation dynamics exhibits logarithmic aging, with aging rates
determined by the distribution of barriers.Comment: 100 pages, 25 figure
Compressed representation of a partially defined integer function over multiple arguments
In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Pseudomonas aeruginosa in vitro Phenotypes Distinguish Cystic Fibrosis Infection Stages and Outcomes
Rationale: Pseudomonas aeruginosa undergoes phenotypic changes during cystic fibrosis (CF) lung infection. Although mucoidy is traditionally associated with transition to chronic infection, we hypothesized that additional in vitro phenotypes correlate with this transition and contribute to disease
An Analysis of the Systemic Risks Posed by Fannie Mae and Freddie Mac and an Evaluation of the Policy Options for Reducing those Risks
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