834 research outputs found
Brachial Artery Vasculitis and Associated Stenosis Presenting as Elbow Pain in a 16-Year-Old Soccer Player: A Case Report
Chronic vascular occlusion in the upper extremity can result from repetitive trauma, atherosclerosis, proximal embolic events, hypercoagulable states, and systemic diseases such as collagen vascular disease and vasculitis. Considerable functional impairment can result from these maladies; however, sometimes the condition develops slowly with minimal effect on the patient. We describe a 16-year-old soccer player with slow-progressing elbow pain and loss of range in motion caused by brachial artery vasculitis and resultant brachial arterial stenosis. Although vascular insults and lesions rarely cause chronic vascular occlusion, physicians should consider this possibility in patients with localized pain or atrophy, especially if the condition develops slowly
An X-Ray View of the Jet-Cycle in the Radio Loud AGN 3C120
We present a study of the central engine in the broad-line radio galaxy 3C120
using a multi-epoch analysis of a deep XMM-Newton observation and two deep
Suzaku pointings (in 2012). In order to place our spectral data into the
context of the disk-disruption/jet-ejection cycles displayed by this object, we
monitor the source in the UV/X-ray bands, and in the radio band. We find three
statistically acceptable spectral models, a disk-reflection model, a jet-model
and a jet+disk model. Despite being good descriptions of the data, the
disk-reflection model violates the radio constraints on the inclination, and
the jet-model has a fine-tuning problem, requiring a jet contribution exceeding
that expected. Thus, we argue for a composite jet+disk model. Within the
context of this model, we verify the basic predictions of the jet-cycle
paradigm, finding a truncated/refilling disk during the Suzaku observations and
a complete disk extending down to the innermost stable circular orbit (ISCO)
during the XMM-Newton observation. The idea of a refilling disk is further
supported by the detection of the ejection of a new jet knot approximately one
month after the Suzaku pointings. We also discover a step-like event in one of
the Suzaku pointings in which the soft band lags the hard band. We suggest that
we are witnessing the propagation of a disturbance from the disk into the jet
on a timescale set by the magnetic field.Comment: 14 pages, 10 figures, accepted for publication in Ap
Comparative transcriptomic analysis of Porphyromonas gingivalis biofilm and planktonic cells
<p>Abstract</p> <p>Background</p> <p><it>Porphyromonas gingivalis </it>in subgingival dental plaque, as part of a mature biofilm, has been strongly implicated in the onset and progression of chronic periodontitis. In this study using DNA microarray we compared the global gene expression of a <it>P. gingivalis </it>biofilm with that of its planktonic counterpart grown in the same continuous culture.</p> <p>Results</p> <p>Approximately 18% (377 genes, at 1.5 fold or more, <it>P</it>-value < 0.01) of the <it>P. gingivalis </it>genome was differentially expressed when the bacterium was grown as a biofilm. Genes that were down-regulated in biofilm cells, relative to planktonic cells, included those involved in cell envelope biogenesis, DNA replication, energy production and biosynthesis of cofactors, prosthetic groups and carriers. A number of genes encoding transport and binding proteins were up-regulated in <it>P. gingivalis </it>biofilm cells. Several genes predicted to encode proteins involved in signal transduction and transcriptional regulation were differentially regulated and may be important in the regulation of biofilm growth.</p> <p>Conclusion</p> <p>This study analyzing global gene expression provides insight into the adaptive response of <it>P. gingivalis </it>to biofilm growth, in particular showing a down regulation of genes involved in growth and metabolic activity.</p
Techno-Economic Feasibility Analysis of a Fully Mobile Radiation Oncology System using Monte Carlo Simulation
PURPOSEDisparities in radiation oncology (RO) can be attributed to geographic location, socioeconomic status, race, sex, and other societal factors. One potential solution is to implement a fully mobile (FM) RO system to bring radiotherapy to rural areas and reduce barriers to access. We use Monte Carlo simulation to quantify techno-economic feasibility with uncertainty, using two rural Missouri scenarios.METHODSRecently, a semimobile RO system has been developed by building an o-ring linear accelerator (linac) into a mobile coach that is used for temporary care, months at a time. Transitioning to a more FM-RO system, which changes location within a given day, presents technical challenges including logistics and quality assurance. This simulation includes cancer census in both northern and southeastern Missouri, multiple treatment locations within a given day, and associated expenditures and revenues. A subset of patients with lung, breast, and rectal diseases, treated with five fractions, was simulated in the FM-RO system.RESULTSThe FM-RO can perform all necessary quality assurance tests as suggested in national medical physics guidelines within 1.5 hours, thus demonstrating technological feasibility. In northern and southeastern Missouri, five-fraction simulations\u27 net incomes were, in US dollars (USD), 3.65 USD ± 0.25 million (approximately 98 patients/year), respectively. The number of patients seen had the highest correlation with net income as well as the ability to break-even within the simulation. The model does not account for disruptions in care or other commonly used treatment paradigms, which may lead to differences in estimated economic return. Overall, the mobile system achieved a net benefit, even for the most negative simulation scenarios.CONCLUSIONOur simulations suggest technologic success and economic viability for a FM-RO system within rural Missouri and present an interesting solution to address other geographic disparities in access to radiotherapy
High resolution Chandra HETG and RXTE observations of GRS 1915+105 : A hot disk atmosphere & cold gas enriched in Iron and Silicon
The time-averaged 30 ks Chandra HETGS observation of the micro-quasar GRS
1915+105 in the low hard state reveals for the first time in this source
neutral K absorption edges from Fe, Si, Mg, & S. Ionized resonance absorption
from H-, and He-like Fe (XXV, XXVI), Ca XX and possibly emission from neutral
Fe Kalpha and ionized Fe XXV (forbidden, or the resonance emission component of
a P-Cygni profile) are also seen. We report the tentative detection of the
first astrophysical signature of XAFS in the photoelectric edge of Si (and
possibly Fe and Mg), attributed to material in grains. The large column
densities measured from the neutral edges reveal anomalous Si and Fe
abundances. Scenarios for which the anomalous abundances can be attributed to
surrounding cold material associated with GRS 1915+105 and/or that the
enrichment may signify either a highly unusual supernova/hypernova, or external
supernova activity local to the binary are discussed. We attribute the ionized
features to a hot disk, disk-wind, or corona environment. These features allow
for constraints on the ionization parameter (log xi > 4.15), temperature (T >
2.4 x 10^6 K), and hydrogen equivalent number density (n > 10^{12} cm^{-3}) for
this region. Variability studies with simultaneous RXTE data show that the
light curve count rate tracks changes in the disk blackbody and the power-law
flux. Spectral changes in the Chandra data also track the behavior of the light
curve, and may point to changes in both the ionizing flux and density of the
absorber. A 3.69 Hz QPO and weak first harmonic is seen in the RXTE data.Comment: Accepted for publication in ApJ., 9 pages, 5 figure
The Far-Infrared Spectral Energy Distributions of X-ray-selected Active Galaxies
[Abridged] We present ISO far-infrared (IR) observations of 21 hard X-ray
selected AGN from the HEAO-1 A2 sample. We compare the far-IR to X-ray spectral
energy distributions (SEDs) of this sample with various radio and optically
selected AGN samples. The hard-X-ray selected sample shows a wider range of
optical/UV shapes extending to redder near-IR colors. The bluer objects are
Seyfert 1s, while the redder AGN are mostly intermediate or type 2 Seyferts.
This is consistent with a modified unification model in which the amount of
obscuring material increases with viewing angle and may be clumpy. Such a
scenario, already suggested by differing optical/near-IR spectroscopic and
X-ray AGN classifications, allows for different amounts of obscuration of the
continuum emission in different wavebands and of the broad emission line region
which results in a mixture of behaviors for AGN with similar optical emission
line classifications. The resulting limits on the column density of obscuring
material through which we are viewing the redder AGN are 100 times lower than
for the standard optically thick torus models. The resulting decrease in
optical depth of the obscuring material allows the AGN to heat more dust at
larger radial distances. We show that an AGN-heated, flared, dusty disk with
mass 10^9 solar and size of few hundred pc is able to generate optical-far-IR
SEDs which reproduce the wide range of SEDs present in our sample with no need
for an additional starburst component to generate the long-wavelength, cooler
part of the IR continuum.Comment: 40 pages, 14 figures, accepted for publication in Astrophysical
Journal, V. 590, June 10, 200
The high-speed X-ray camera on AXIS
AXIS is a Probe-class mission concept that will provide high-throughput,
high-spatial-resolution X-ray spectral imaging, enabling transformative studies
of high-energy astrophysical phenomena. To take advantage of the advanced
optics and avoid photon pile-up, the AXIS focal plane requires detectors with
readout rates at least 20 times faster than previous soft X-ray imaging
spectrometers flying aboard missions such as Chandra and Suzaku, while
retaining the low noise, excellent spectral performance, and low power
requirements of those instruments. We present the design of the AXIS high-speed
X-ray camera, which baselines large-format MIT Lincoln Laboratory CCDs
employing low-noise pJFET output amplifiers and a single-layer polysilicon gate
structure that allows fast, low-power clocking. These detectors are combined
with an integrated high-speed, low-noise ASIC readout chip from Stanford
University that provides better performance than conventional discrete
solutions at a fraction of their power consumption and footprint. Our
complementary front-end electronics concept employs state of the art digital
video waveform capture and advanced signal processing to deliver low noise at
high speed. We review the current performance of this technology, highlighting
recent improvements on prototype devices that achieve excellent noise
characteristics at the required readout rate. We present measurements of the
CCD spectral response across the AXIS energy band, augmenting lab measurements
with detector simulations that help us understand sources of charge loss and
evaluate the quality of the CCD backside passivation technique. We show that
our technology is on a path that will meet our requirements and enable AXIS to
achieve world-class science.Comment: 17 pages, 11 figures, submitted to Proceedings of SPIE Optics +
Photonics 202
Amygdala and Ventrolateral Prefrontal Cortex Function during Anticipated Peer Evaluation in Pediatric Social Anxiety
1. Context. Amygdala and ventrolateral prefrontal cortex dysfunction manifests in adolescents with anxiety disorders when they view negatively-valenced stimuli in threatening contexts. Such fear-circuitry dysfunction may also manifest when anticipated social evaluation leads socially anxious adolescents to misperceive peers as threatening. 2. Objective. To determine whether photographs of negatively-evaluated smiling peers, viewed during anticipated evaluation, engage the amygdala and ventrolateral prefrontal cortex differentially in adolescents with and without social anxiety. 3. Design. Case-control study. 4. Setting. Government clinical research institute. 5. Participants. Fourteen adolescents with anxiety disorders associated with marked social concerns and 14 diagnosis-free adolescents, matched on sex, age, IQ, and socio-economic status. 6. Main Outcome Measure(s). Blood oxygenation level-dependent signal measured with event-related functional magnetic resonance imaging. Before and during neuroimaging scans, participants anticipating social evaluation completed peer- and self-appraisals. Event-related analyses were tailored to participants’ ratings of specific peers. 7. Results. Participants classified 40 pictures of same-age peers as ones they wanted to engage or not engage with for a social interaction. Anxious adolescents showed greater amygdala activation than healthy adolescents when anticipating evaluation from peers rated as undesired for an interaction. Viewing undesired peers engaged stronger positive amygdala-ventrolateral-prefrontal-cortex connectivity in anxious vs. healthy adolescents. 8. Conclusions. Anticipating social evaluation from negatively-perceived peers modulates amygdala and ventrolateral prefrontal cortex engagement differentially in anxious and healthy 3 adolescents. Amygdala and ventrolateral prefrontal cortex abnormalities in adolescent anxiety disorders are heightened in specific contexts of potential peer evaluation
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