2,521 research outputs found
Wave propagation and earth satellite radio emission studies
Radio propagation studies of the ionosphere using satellite radio beacons are described. The ionosphere is known as a dispersive, inhomogeneous, irregular and sometimes even nonlinear medium. After traversing through the ionosphere the radio signal bears signatures of these characteristics. A study of these signatures will be helpful in two areas: (1) It will assist in learning the behavior of the medium, in this case the ionosphere. (2) It will provide information of the kind of signal characteristics and statistics to be expected for communication and navigational satellite systems that use the similar geometry
Application of Fast Pressure Sensitive Paint in Hypervelocity Flow
The development of fast responding pressure sensitive paints for measurements in high-enthalpy, hypersonic flows is reported. Data are obtained for at plate boundary layers in
an impulse facility with typical test gas times on the order of hundreds of microseconds.
The fast pressure sensitive paint is found to have the required response time and sufficient
signal level to visualize vortical boundary layer structures in a Mach 5.12 freestream. The
flow behind protuberance strips with different geometries is evaluated with measurements
of the vortex frequency and diameter, as well as breakdown distance. Comparisons with
static pressure measurements made using pressure taps show differences of up to a factor
of three, and calibration sources as well as an alternative lifetime measurement method
remain to be investigated
Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti
We present ~0.4 resolution images of CO(3-2) and associated continuum
emission from the gas-bearing debris disk around the nearby A star 49 Ceti,
observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). We
analyze the ALMA visibilities in tandem with the broad-band spectral energy
distribution to measure the radial surface density profiles of dust and gas
emission from the system. The dust surface density decreases with radius
between ~100 and 310 au, with a marginally significant enhancement of surface
density at a radius of ~110 au. The SED requires an inner disk of small grains
in addition to the outer disk of larger grains resolved by ALMA. The gas disk
exhibits a surface density profile that increases with radius, contrary to most
previous spatially resolved observations of circumstellar gas disks. While ~80%
of the CO flux is well described by an axisymmetric power-law disk in Keplerian
rotation about the central star, residuals at ~20% of the peak flux exhibit a
departure from axisymmetry suggestive of spiral arms or a warp in the gas disk.
The radial extent of the gas disk (~220 au) is smaller than that of the dust
disk (~300 au), consistent with recent observations of other gas-bearing debris
disks. While there are so far only three broad debris disks with well
characterized radial dust profiles at millimeter wavelengths, 49 Ceti's disk
shows a markedly different structure from two radially resolved gas-poor debris
disks, implying that the physical processes generating and sculpting the gas
and dust are fundamentally different.Comment: 20 pages, 8 figures, accepted for publication in ApJ March 31, 2017
(submitted Nov 2016
Expression of Drug Targets in Patients Treated with Sorafenib, Carboplatin and Paclitaxel
Introduction: Sorafenib, a multitarget kinase inhibitor, targets members of the mitogen-activated protein kinase (MAPK) pathway and VEGFR kinases. Here we assessed the association between expression of sorafenib targets and biomarkers of taxane sensitivity and response to therapy in pre-treatment tumors from patients enrolled in ECOG 2603, a phase III comparing sorafenib, carboplatin and paclitaxel (SCP) to carboplatin, paclitaxel and placebo (CP). Methods: Using a method of automated quantitative analysis (AQUA) of in situ protein expression, we quantified expression of VEGF-R2, VEGF-R1, VEGF-R3, FGF-R1, PDGF-Rβ, c-Kit, B-Raf, C-Raf, MEK1, ERK1/2, STMN1, MAP2, EB1 and Bcl-2 in pretreatment specimens from 263 patients. Results: An association was found between high FGF-R1 and VEGF-R1 and increased progression-free survival (PFS) and overall survival (OS) in our combined cohort (SCP and CP arms). Expression of FGF-R1 and VEGF-R1 was higher in patients who responded to therapy ((CR+PR) vs. (SD+PD+ un-evaluable)). Conclusions: In light of the absence of treatment effect associated with sorafenib, the association found between FGF-R1 and VEGF-R1 expression and OS, PFS and response might reflect a predictive biomarker signature for carboplatin/paclitaxel-based therapy. Seeing that carboplatin and pacitaxel are now widely used for this disease, corroboration in another cohort might enable us to improve the therapeutic ratio of this regimen. © 2013 Jilaveanu et al
Streamlining screening of emotional function in Veterans with traumatic brain injury
ObjectivesThis study examined how depression, anxiety, and sleep items from the Neurobehavioral Symptom Inventory (NSI) predict results from longer inventories.MethodThis was a retrospective review from 484, predominantly male (96.1%) Veterans, mean age 29.7 years, who underwent brief neuropsychological screening during a comprehensive, multidisciplinary evaluation for mild traumatic brain injury (TBI). Participants completed the NSI, insomnia severity index (ISI), and hospital anxiety and depression scale (HADS).Results: Overall,97.1% who endorsed “severe”/“very severe” anxiety on the NSI had significant anxiety on the HADS; 85% reporting “severe”/“very severe” depression on the NSI, had significant depression on the HADS; and 97.7% reporting “severe”/“very severe” sleep problems on the NSI, had significant sleep difficulties on the ISI.ConclusionClose correspondence between “severe”/“very severe” symptoms on the NSI and lengthier checklists suggests additional checklists may be eliminated and individuals can be referred for mental health treatment. NSI reports of “mild”/“moderate” require further screening.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144598/1/jclp22595_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144598/2/jclp22595.pd
The Outburst of V1647 Ori Revealed by Spitzer
We present Spitzer Space Telescope observations of V1647 Ori, the outbursting
source lighting McNeil's nebula, taken near the optical peak of the outburst in
early March 2004. The source is easily detected in all Spitzer imaging bands
from 3.6 - 70 microns. The fluxes at all wavelengths are roughly a factor of 15
brighter than pre-outburst levels; we measure a bolometric luminosity of 44
Lsun. We posit that this event is due to an increase in the accretion
luminosity of the source. Simple models of an accretion disk plus tenuous
envelope can qualitatively explain the observed pre- and post-outburst spectral
energy distributions. The accretion activity implied by our results indicates
that the outburst may be intermediate between FUor and EXor-type events. We
also report the discovery of a previously unknown mid-infrared counterpart to
the nearby Herbig-Haro object HH 22.Comment: 12 pages, 3 figures, accepted by ApJ Letter
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