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Time From Booking Until Appointment and Healthcare Utilization in Hand Surgery Patients With Discretionary Conditions
Delaying medical therapy for benign musculoskeletal conditions may allow patients to
develop coping strategies, resulting in less need for medical intervention and reduced cost.
Our primary question was whether time from booking until appointment is associated with
healthcare costs. Our secondary question was whether time from booking to appointment is
associated with healthcare utilizations, including imaging, injections, nerve conduction
studies, occupational therapy visits, surgery, referrals, and second opinions.
We identified 16,750 patients making a first clinic visit to a hand surgery practice from 2003
through 2012. Utilizations were determined until the patient’s second visit. Costs were
determined in Relative Value Units. In multivariable models, duration between booking and
office visit was not associated with higher cost. Duration between booking and office visit
was associated with a higher rate of nerve conduction studies (P < 0.001) and a lower rate
of occupational therapy (P < 0.001). We observed substantial variation in cost and
utilization based on treating surgeon. In a setting with relatively short wait times, greater
wait time was not therapeutic, but is associated with different diagnostic and treatment
measures. The variations by surgeon may make variations based on other factors including
time between booking and appointment difficult to discern
The Supernova Remnant G296.7-0.9 in X-rays
Aims: We present a detailed study of the supernova remnant (SNR) G296.7-0.9
in the 0.2-12 keV X-ray band.
Methods: Using data from XMM-Newton we performed a spectro-imaging analysis
of G296.7-0.9 in order to deduce the basic parameters of the remnant and to
search for evidence of a young neutron star associated with it.
Results: In X-rays the remnant is characterized by a bright arc located in
the south-west direction. Its X-ray spectrum can best be described by an
absorbed non-equilibrium collisional plasma model with a hydrogen density of
N_H=1.24_{-0.05}^{+0.07} x 10^{22} cm^{-2} and a plasma temperature of
6.2^{+0.9}_{-0.8} million Kelvin. The analysis revealed a remnant age of 5800
to 7600 years and a distance of 9.8_{-0.7}^{+1.1} kpc. The latter suggests a
spatial connection with a close-by HII region. We did not find evidence for a
young neutron star associated with the remnant.Comment: accepted by A&A, 5 pages, 2 figure
The Local Leo Cold Cloud and New Limits on a Local Hot Bubble
We present a multi-wavelength study of the local Leo cold cloud (LLCC), a
very nearby, very cold cloud in the interstellar medium. Through stellar
absorption studies we find that the LLCC is between 11.3 pc and 24.3 pc away,
making it the closest known cold neutral medium cloud and well within the
boundaries of the local cavity. Observations of the cloud in the 21-cm HI line
reveal that the LLCC is very cold, with temperatures ranging from 15 K to 30 K,
and is best fit with a model composed of two colliding components. The cloud
has associated 100 micron thermal dust emission, pointing to a somewhat low
dust-to-gas ratio of 48 x 10^-22 MJy sr^-1 cm^2. We find that the LLCC is too
far away to be generated by the collision among the nearby complex of local
interstellar clouds, but that the small relative velocities indicate that the
LLCC is somehow related to these clouds. We use the LLCC to conduct a shadowing
experiment in 1/4 keV X-rays, allowing us to differentiate between different
possible origins for the observed soft X-ray background. We find that a local
hot bubble model alone cannot account for the low-latitude soft X-ray
background, but that isotropic emission from solar wind charge exchange does
reproduce our data. In a combined local hot bubble and solar wind charge
exchange scenario, we rule out emission from a local hot bubble with an 1/4 keV
emissivity greater than 1.1 Snowdens / pc at 3 sigma, 4 times lower than
previous estimates. This result dramatically changes our perspective on our
local interstellar medium.Comment: 13 pages, 12 figures. Accepted for publication in the Astrophysical
Journal. Vector figure version available at
http://www.astro.columbia.edu/~jpeek
The Chandra ACIS Survey of M33 (ChASeM33): The final source catalog
This study presents the final source catalog of the Chandra ACIS Survey of
M33 (ChASeM33). With a total exposure time of 1.4 Ms, ChASeM33 covers ~70% of
the D25 isophote (R\approx4kpc) of M33 and provides the deepest, most complete,
and detailed look at a spiral galaxy in X-rays. The source catalog includes 662
sources, reaches a limiting unabsorbed luminosity of ~2.4x10^(34) erg/s in the
0.35-8.0keV energy band, and contains source positions, source net counts,
fluxes and significances in several energy bands, and information on source
variability. The analysis challenges posed by ChASeM33 and the techniques
adopted to address these challenges are discussed. To constrain the nature of
the detected X-ray source, hardness ratios were constructed and spectra were
fit for 254 sources, followup MMT spectra of 116 sources were acquired, and
cross-correlations with previous X-ray catalogs and other multi-wavelength data
were generated. Based on this effort, 183 of the 662 ChASeM33 sources could be
identified. Finally, the luminosity function for the detected point sources as
well as the one for the X-ray binaries in M33 is presented. The luminosity
functions in the soft band (0.5-2.0 keV) and the hard band (2.0-8.0 keV) have a
limiting luminosity at the 90% completeness limit of 4.0x10^(34) erg/s and
1.6x10^(35) erg/s (for D=817kpc), respectively, which is significantly lower
than what was reported by previous X-ray binary population studies in galaxies
more distant than M33. The resulting distribution is consistent with a dominant
population of high mass X-ray binaries as would be expected for M33.Comment: 186 pages, 11 figures, 10 tables. Accepted for publication in the
ApJS. For a high resolution version of the paper, see
http://hea-www.harvard.edu/vlp_m33_public
A statistical mechanical description of metastable states and hysteresis in the 3D soft-spin random-field model at T=0
We present a formalism for computing the complexity of metastable states and
the zero-temperature magnetic hysteresis loop in the soft-spin random-field
model in finite dimensions. The complexity is obtained as the Legendre
transform of the free-energy associated to a certain action in replica space
and the hysteresis loop above the critical disorder is defined as the curve in
the field-magnetization plane where the complexity vanishes; the nonequilibrium
magnetization is therefore obtained without having to follow the dynamical
evolution. We use approximations borrowed from condensed-matter theory and
based on assumptions on the structure of the direct correlation functions (or
proper vertices), such as a local approximation for the self-energies, to
calculate the hysteresis loop in three dimensions, the correlation functions
along the loop, and the second moment of the avalanche-size distribution.Comment: 28 pages, 12 figure
A Hard X-ray Study of the Normal Star-Forming Galaxy M83 with NuSTAR
We present results from sensitive, multi-epoch NuSTAR observations of the
late-type star-forming galaxy M83 (d=4.6 Mpc), which is the first investigation
to spatially resolve the hard (E>10 keV) X-ray emission of this galaxy. The
nuclear region and ~ 20 off-nuclear point sources, including a previously
discovered ultraluminous X-ray (ULX) source, are detected in our NuSTAR
observations. The X-ray hardnesses and luminosities of the majority of the
point sources are consistent with hard X-ray sources resolved in the starburst
galaxy NGC 253. We infer that the hard X-ray emission is most likely dominated
by intermediate accretion state black hole binaries and neutron star low-mass
X-ray binaries (Z-sources). We construct the X-ray binary luminosity function
(XLF) in the NuSTAR band for an extragalactic environment for the first time.
The M83 XLF has a steeper XLF than the X-ray binary XLF in NGC 253, consistent
with previous measurements by Chandra at softer X-ray energies. The NuSTAR
integrated galaxy spectrum of M83 drops quickly above 10 keV, which is also
seen in the starburst galaxies NGC253, NGC 3310 and NGC 3256. The NuSTAR
observations constrain any AGN to be either highly obscured or to have an
extremely low luminosity of 10 erg/s (10-30 keV), implying it
is emitting at a very low Eddington ratio. An X-ray point source consistent
with the location of the nuclear star cluster with an X-ray luminosity of a few
times 10 erg/s may be a low-luminosity AGN but is more consistent with
being an X-ray binary.Comment: Accepted for publication in ApJ (25 pages, 17 figures
Direct ink writing of ultra-high temperature ceramics
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Chandra Observation of Luminous and Ultraluminous X-ray Binaries in M101
X-ray binaries in the Milky Way are among the brightest objects on the X-ray
sky. With the increasing sensitivity of recent missions, it is now possible to
study X-ray binaries in nearby galaxies. We present data on six luminous
sources in the nearby spiral galaxy, M101, obtained with the Chandra ACIS-S. Of
these, five appear to be similar to ultraluminous sources in other galaxies,
while the brightest source, P098, shows some unique characteristics. We present
our interpretation of the data in terms of an optically thick outflow, and
discuss implications.Comment: Accepted for publication in Astrophysical Journal (16 pages including
4 figures
Tidal interaction vs. ram pressure stripping effects as seen in X-rays. Hot gas in group and cluster galaxies
The hot intracluster/intragroup medium (ICM/IGM) and a high galaxy density
can lead to perturbations of the galactic interstellar medium (ISM) due to ram
pressure and/or tidal interaction effects. In radio polarimetry observations,
both phenomena may manifest similar features. X-ray data can help to determine
the real origin of the perturbation. We analyse the distribution and physical
properties of the hot gas in the Virgo cluster spiral galaxies NGC 4254 and NGC
4569, which indicate that the cluster environment has had a significant
influence on their properties. By performing both spatial and spectral analyses
of X-ray data, we try to distinguish between two major phenomena: tidal and ram
pressure interactions. We compare our findings with the case of NGC 2276, in
which a shock was reported, by analysing XMM-Newton X-ray data for this galaxy.
We use archival XMM-Newton observations of NGC 4254, NGC 4569, and NGC 2276.
Maps of the soft diffuse emission in the energy band 0.2 - 1 keV are obtained.
For the three galaxies, especially at the position of magnetic field
enhancements we perform a spectral analysis to derive gas temperatures and thus
to look for shock signatures. A shock is a signature of ram pressure resulting
from supersonic velocities; weak tidal interactions are not expected to
influence the temperature of the ionized gas. In NGC 4254, we do not observe
any temperature increase. This suggests tidal interactions rather than ram
pressure stripping. In NGC 4569 the radio polarized ridge shows a higher
temperature, which may indicate ram-pressure effects. For NGC 2276, we do not
find clear indications of a shock. The main driver of the observed distortions
is most likely tidal interaction. Determining gas temperatures via sensitive
X-ray observations seems to be a good method for distinguishing between ram
pressure and tidal interaction effects acting upon a galaxy.Comment: 13 pages, 13 figures, 8 tables, Accepted for publication in Astronomy
and Astrophysic
Evaluation of potential of high Si high C steel nanostructured bainite for wear and fatigue applications
The present study is concerned with the potential of high carbon, high silicon steel grades isothermally transformed to bainite at low temperature (<300 C). The first part gives an overview of the design principles, allowing very high strength and ductility to be achieved while minimising transformation duration. Wear and fatigue properties are then investigated for over 10 variants of such materials, manufactured in the laboratory or industrially. The results are discussed against published data. Tensile strengths above 2 GPa are routinely achieved, with, in one case, an exceptional and unprecedented total elongation of over 20%. Bainite plate thickness and retained austenite content are shown to be important factors in controlling the yield strength, though additional, non-negligible parameters remain to be quantified. Rolling-sliding wear performances are found to be exceptional, with as little as 1% of the specific wear rate of conventional 100Cr6 isothermally transformed to bainite. It is suggested that this results from the decomposition of retained austenite in the worn layer, which considerably increases hardness and presumably introduces compressive residual stresses. Fatigue performance was slightly improved over 100Cr6 for one of the two industrially produced materials but significantly lower otherwise. Factors controlling fatigue resistance require further investigations. © 2013 Institute of Materials, Minerals and Mining Published by Maney on behalf of the Institute.Peer Reviewe
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