1,899 research outputs found
Microwave ISM Emission in the Green Bank Galactic Plane Survey: Evidence for Spinning Dust
We observe significant dust-correlated emission outside of H II regions in
the Green Bank Galactic Plane Survey (-4 < b < 4 degrees) at 8.35 and 14.35
GHz. The rising spectral slope rules out synchrotron and free-free emission as
majority constituents at 14 GHz, and the amplitude is at least 500 times higher
than expected thermal dust emission. When combined with the Rhodes (2.326 GHz),
and WMAP (23-94 GHz) data it is possible to fit dust-correlated emission at
2.3-94 GHz with only soft synchrotron, free-free, thermal dust, and an
additional dust-correlated component similar to Draine & Lazarian spinning
dust. The rising component generally dominates free-free and synchrotron for
\nu >~ 14 GHz and is overwhelmed by thermal dust at \nu > 60 GHz. The current
data fulfill most of the criteria laid out by Finkbeiner et al. (2002) for
detection of spinning dust.Comment: ApJ in press. 26 pages, 11 figures, figures jpeg compressed to save
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Aeroelastic model helicopter rotor testing in the Langley TDT
Wind-tunnel testing of a properly scaled aeroelastic model helicopter rotor is considered a necessary phase in the design development of new or existing rotor systems. For this reason, extensive testing of aeroelastically scaled model rotors is done in the Transonic Dynamics Tunnel (TDT) located at the NASA Langley Research Center. A unique capability of this facility, which enables proper dynamic scaling, is the use of Freon as a test medium. A description of the TDT and a discussion of the benefits of using Freon as a test medium are presented. A description of the model test bed used, the Aeroelastic Rotor Experimental System (ARES), is also provided and examples of recent rotor tests are cited to illustrate the advantages and capabilities of aeroelastic model rotor testing in the TDT. The importance of proper dynamic scaling in identifying and solving rotorcraft aeroelastic problems, and the importance of aeroelastic testing of model rotor systems in the design of advanced rotor systems are demonstrated
An experimental study of the sensitivity of helicopter rotor blade tracking to root pitch adjustment in hover
The sensitivity of blade tracking in hover to variations in root pitch was examined for two rotor configurations. Tests were conducted using a four bladed articulated rotor mounted on the NASA-Army aeroelastic rotor experimental system (ARES). Two rotor configurations were tested: one consisting of a blade set with flexible fiberglass spars and one with stiffer (by a factor of five in flapwise and torsional stiffnesses) aluminum spars. Both blade sets were identical in planform and airfoil distribution and were untwisted. The two configurations were ballasted to the same Lock number so that a direct comparison of the tracking sensitivity to a gross change in blade stiffness could be made. Experimental results show no large differences between the two sets of blades in the sensitivity of the blade tracking to root pitch adjustments. However, a measurable reduction in intrack coning of the fiberglass spar blades with respect to the aluminum blades is noted at higher rotor thrust conditions
Constraints on changes in fundamental constants from a cosmologically distant OH absorber/emitter
We have detected the four 18cm OH lines from the gravitational
lens toward PMN J0134-0931. The 1612 and 1720 MHz lines are in conjugate
absorption and emission, providing a laboratory to test the evolution of
fundamental constants over a large lookback time. We compare the HI and OH main
line absorption redshifts of the different components in the
absorber and the lens toward B0218+357 to place stringent
constraints on changes in . We obtain
,
consistent with no evolution over the redshift range . The
measurements have a sensitivity of or to fractional
changes in and over a period of Gyr, half the age of
the Universe. These are among the most sensitive current constraints on changes
in .Comment: 4 pages, 3 figures. Final version, with minor changes to match the
version in print in Phys. Rev. Let
Therapies to Slow, Stop, or Reverse Parkinson's Disease
Our understanding of PD pathophysiology is vastly improved compared to the situation 20 years ago. We have identified the major genetic risks for PD, we now have far more representative animal models of the disease, and we can be inspired by the early successes of others using Antisense Oligonucleotide and vaccination approaches in other neurodegenerative diseases. We also have a broad range of repurposed drugs showing the first signals of potential efficacy in the translational pipeline which are being driven forward through the various clinical trial stages. We believe we can be optimistic that the next 20 years will be a time for major breakthroughs towards the discovery of therapies that may slow, stop, or reverse PD
Constraints on changes in fundamental constants from a cosmologically distant OH absorber or emitter
We have detected the four 18 cm OH lines from the z∼0.765 gravitational lens toward PMN J0134–0931. The 1612 and 1720 MHz lines are in conjugate absorption and emission, providing a laboratory to test the evolution of fundamental constants over a large lookback time. We compare the HI and OH main line absorption redshifts of the different components in the z∼0.765 absorber and the z∼0.685 lens toward B0218+357 to place stringent constraints on changes in F≡gp[α2/μ]1.57. We obtain [ΔF/F]=(0.44±0.36stat±1.0syst)×10-5, consistent with no evolution over the redshift range 0<z≲0.7. The measurements have a 2σ sensitivity of [Δα/α]<6.7×10-6 or [Δμ/μ]<1.4×10-5 to fractional changes in α and μ over a period of ∼6.5 G yr, half the age of the Universe. These are among the most sensitive constraints on changes in μ
Development and Evolution of a Statewide Outpatient Consultation Service: Leveraging Telemedicine to Improve Access to Specialty Care
Despite a robust health care system in the United States, many Americans experience health care disparities as a result of poor access to medical care. Academic medicine plays an important role in addressing health care disparities by providing primary and specialty care for the poor and uninsured. In South Carolina, 43 of its 46 counties are designated as fully or partially Medically Underserved Areas (MUAs), defined as areas with a shortage of medical providers, high infant mortality, and either high elderly population or high poverty rates. To address these health care disparities, an academic medical center in South Carolina created a hub-and-spoke specialty care model using telemedicine in partnership with primary care providers across community settings. Initial private foundation grant funding enabled the development and dissemination of technology to provide remote teleconsultations by physicians at the academic medical center (hub) to patients in their primary care offices (spoke). This model, now supported by recurring state funding and professional billing, provides much-needed services, including psychiatry, nutrition counseling, and various surgical and medical subspecialties, to rural and underserved populations in the state. This manuscript provides a narrative review of the development of this statewide telemedicine service, with an emphasis on identification of stakeholders, technology issues, barriers to implementation, and future directions
Anomalous Microwave Emission from the HII region RCW175
We present evidence for anomalous microwave emission in the RCW175 \hii
region. Motivated by 33 GHz 13\arcmin resolution data from the Very Small
Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager
(CBI) at a resolution of 4\arcmin. The region consists of two distinct
components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise
ratio. The integrated flux density is Jy at 31 GHz, in good
agreement with the VSA. The 31 GHz flux density is Jy
() above the expected value from optically thin free-free emission
based on lower frequency radio data and thermal dust constrained by IRAS and
WMAP data. Conventional emission mechanisms such as optically thick emission
from ultracompact \hii regions cannot easily account for this excess. We
interpret the excess as evidence for electric dipole emission from small
spinning dust grains, which does provide an adequate fit to the data.Comment: 5 pages, 2 figures, submmited to ApJ Letter
Quasi-simultaneous multi-frequency observations of inverted-spectrum GPS candidate sources
Gigahertz-Peaked Spectrum (GPS) sources are probably the precursors of local
radio galaxies.Existing GPS source samples are small (<200). It is necessary to
extend the availabe sample of the Gigahertz-Peaked Spectrum (GPS) and High
Frequency Peaker (HFP) sources in order to study their nature with greater
details and higher statistical significance. A sample of 214 radio sources,
which were extracted from the SPECFIND catalog and show an inverted radio
spectrum, were observed quasi-simultaneously at 4.85, 10.45, and 32GHz with the
100-m Effelsberg radio telescope. Using the VLBA calibrator survey (VCS) we
have investigated the parsec-scale morphology of the sources. About 45% of the
sources in our sample are classified as GPS or HFP candidates. We add 65 new
GPS/HFP candidates to existing samples. We confirm the expected tendency that
HFP are more compact on milliarcsecond scale than the 'classical' GPS sources,
which peak at lower frequencies. The data mining of the SPECFIND database
represents a promising tool for the discovery of new GPS/HFP sources.Comment: 16 pages, 7 figures, accepted for publication in A&
A low H I column density filament in NGC 2403 : signature of interaction or accretion
Date of acceptance: 12/07/2014Observed H i accretion around nearby galaxies can only account for a fraction of the gas supply needed to sustain the currently observed star formation rates. It is possible that additional accretion occurs in the form of low column density cold flows, as predicted by numerical simulations of galaxy formation. To constrain the presence and properties of such flows, we present deep H i observations obtained with the NRAO Green Bank Telescope of an area measuring 4° × 4° around NGC 2403. These observations, with a 5σ detection limit of 2.4 × 1018 cm-2 over a 20 km s-1 linewidth, reveal a low column density, extended cloud outside the main H i disk, about 17′ (~ 16 kpc or ~ 2 R25) to the NW of the center of the galaxy. The total H i mass of the cloud is 6.3 × 106 M⊙, or 0.15 percent of the total H i mass of NGC 2403. The cloud is associated with an 8 kpc anomalous-velocity H i filament in the inner disk, that was previously observed in deep VLA observations. We discuss several scenarios for the origin of the cloud, and conclude that it is either accreting from the intergalactic medium, or is the result of a minor interaction with a neigboring dwarf galaxyPeer reviewe
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