2,943 research outputs found

    Nuclear star formation on 100 parsec scales: 10" resolution radio continuum, HI and CO observations

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    A program of radio line and continuum studies of star formation in nearby spiral galaxies is reported. The objective is a search for hot gas and peculiar dynamics in spiral nuclei with 10" to 30" angular resolution. Vigorous star formation is found to be a common phenomenon in the inner kpc of spirals. Arcsecond resolution observations of radio continuum emission at 6 and 2 cm were used to separate the thermal and nonthermal radio components. It was found that thermal and nonthermal emission are well mixed even on sizescales of 10 pc. To understand the reason for the increased level of star formation activity in spiral nuclei, HI and CO emission in these galaxies is studied. The CO transition was detected in M51, M82, NGC 253, NGC 6946 and IC 342 with T sub a approx. 0.5 to 2.0 K, at 20" angular resolution. The dynamics and spatial distribution of nuclear gas are being studied using VLA HI maps with 30" synthesized beams. Evidence for noncircular motions in HI was found in the nucleus of IC 342

    Theoretically-Driven Infrastructure for Supporting Health Care Teams Training at a Military Treatment Facility

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    Designated a Department of Defense Team Resource Center (TRC) in 2008, Naval Medical Center Portsmouth (NMCP) currently hosts three tri-service health care teams training courses annually. Each consists of didactic learning coupled with simulation-based training exercises to provide an interactive educational experience for health care professionals. Simulated cases are developed to reinforce specific teamwork skills and behaviors, and to incorporate a variety of technologies including standardized patients, manikins, and virtual reality. The course is also the foundation of a research program designed to explore applications of modeling and simulation for enhanced team training in health care. The TRC has adopted two theoretical frameworks for evaluating training efficacy and outcomes, and has used these frameworks to guide a systematic reconfiguration of the infrastructure supporting health care teams training at NMCP

    Theoretically-Driven Infrastructure for Supporting Healthcare Teams Training at a Military Treatment Facility

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    The Team Resource Center (TRC) at Naval Medical Center Portsmouth (NMCP) currently hosts a tri-service healthcare teams training course three times annually . The course consists of didactic learning coupled with simulation exercises to provide an interactive educational experience for healthcare professionals. The course is also the foundation of a research program designed to explore the use of simulation technologies for enhancing team training and evaluation. The TRC has adopted theoretical frameworks for evaluating training readiness and efficacy, and is using these frameworks to guide a systematic reconfiguration of the infrastructure supporting healthcare teams training and research initiatives at NMCP

    The Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission

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    The Lunar Atmosphere and Dust Environment Explorer (LADEE) is a Lunar science orbiter mission currently under development to address the goals of the National Research Council decadal surveys and the recent "Scientific Context for Exploration of the Moon" (SCEM) [1] report to study the pristine state of the lunar atmosphere and dust environment prior to significant human activities. LADEE will determine the composition of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions. LADEE will also determine whether dust is present in the lunar exosphere, and reveal the processes that contribute to its sources and variability. These investigations are relevant to our understanding of surface boundary exospheres and dust processes throughout the solar system, address questions regarding the origin and evolution of lunar volatiles, and have potential implications for future exploration activities. LADEE employs a high heritage science instrument payload including a neutral mass spectrometer, ultraviolet spectrometer, and dust sensor. In addition to the science payloads, LADEE will fly a laser communications system technology demonstration that could provide a building block for future space communications architectures. LADEE is an important component in NASA's portfolio of near-term lunar missions, addressing objectives that are currently not covered by other U.S. or international efforts, and whose observations must be conducted before large-scale human or robotic activities irrevocably perturb the tenuous and fragile lunar atmosphere. LADEE will also demonstrate the effectiveness of a low-cost, rapid-development program utilizing a modular bus design launched on the new Minotaur V launch vehicle. Once proven, this capability could enable future lunar missions in a highly cost constrained environment. This paper describes the LADEE objectives, mission design, and technical approach

    The Sunburst Arc: Direct Lyman {\alpha} escape observed in the brightest known lensed galaxy

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    We present rest-frame ultraviolet and optical spectroscopy of the brightest lensed galaxy yet discovered, at redshift z = 2.4. This source reveals a characteristic, triple-peaked Lyman {\alpha} profile which has been predicted by various theoretical works but to our knowledge has not been unambiguously observed previously. The feature is well fit by a superposition of two components: a double-peak profile emerging from substantial radiative transfer, and a narrow, central component resulting from directly escaping Lyman {\alpha} photons; but is poorly fit by either component alone. We demonstrate that the feature is unlikely to contain contamination from nearby sources, and that the central peak is unaffected by radiative transfer effects apart from very slight absorption. The feature is detected at signal-to-noise ratios exceeding 80 per pixel at line center, and bears strong resemblance to synthetic profiles predicted by numerical models.Comment: Accepted for publication in Astronomy & Astrophysics. 4 pages, 5 figure

    Auditory In-Vehicle Technologies to Support Older Drivers

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    OBJECTIVES Population aging, in combination with improved health care and more active lifestyles well into advanced age, have resulted in an increased number of older adults driving more miles than ever before. Unfortunately, these older drivers are over-represented in motor vehicle crashes and crash-related fatalities. Rather than the risk-tasking behaviors observed in young drivers, the collisions of older drivers frequently involve perceptual-cognitive errors. Advanced in-vehicle technologies have the potential to function as sensory-cognitive aids and may offset the negative impact of age-related changes in sensory and cognitive abilities. Collision Avoidance Systems (CASs) function as sensory aids to augment hazard detection capabilities, and therefore may be of particular benefit to older drivers. Navigation aids can offset the working memory requirements of wayfinding, and auditory guidance directions may reduce the visual demands of searching for street signs and reading maps. However, these advanced systems also have the potential to increase the information processing demands of the driving task or distract drivers, particularly if they are not designed in accordance with the sensory and perceptual capabilities of older adults. A series of experiments aimed at examining the impact of sensory-cognitive characteristics of auditory navigational aids on driver wayfinding, performance on a visual peripheral detection task, and neurophysiological, behavioral and subjective indices of driver mental workload and performance were conducted. METHODS Results of two investigations will be discussed. The first investigation examined the impact of amplitude level on working memory. Older adults frequently exhibit reduced complex working memory span. However, recent evidence indicates that increasing a sound’s amplitude increases its duration in echoic memory (Baldwin, in press). Based on these findings, we hypothesized that increasing the amplitude of verbal material would improve working memory efficiency. RESULTS In support of this hypothesis, a strong positive correlation between the amplitude level at which the verbal material was presented and complex working memory span as measured by a version of Daneman and Carpenter’s (1980) Listening span task was observed. This positive relationship OBJECTIVES Population aging, in combination with improved health care and more active lifestyles well into advanced age, have resulted in an increased number of older adults driving more miles than ever before. Unfortunately, these older drivers are over-represented in motor vehicle crashes and crash-related fatalities. Rather than the risk-tasking behaviors observed in young drivers, the collisions of older drivers frequently involve perceptual-cognitive errors. Advanced in-vehicle technologies have the potential to function as sensory-cognitive aids and may offset the negative impact of age-related changes in sensory and cognitive abilities. Collision Avoidance Systems (CASs) function as sensory aids to augment hazard detection capabilities, and therefore may be of particular benefit to older drivers. Navigation aids can offset the working memory requirements of wayfinding, and auditory guidance directions may reduce the visual demands of searching for street signs and reading maps. However, these advanced systems also have the potential to increase the information processing demands of the driving task or distract drivers, particularly if they are not designed in accordance with the sensory and perceptual capabilities of older adults. A series of experiments aimed at examining the impact of sensory-cognitive characteristics of auditory navigational aids on driver wayfinding, performance on a visual peripheral detection task, and neurophysiological, behavioral and subjective indices of driver mental workload and performance were conducted. METHODS Results of two investigations will be discussed. The first investigation examined the impact of amplitude level on working memory. Older adults frequently exhibit reduced complex working memory span. However, recent evidence indicates that increasing a sound’s amplitude increases its duration in echoic memory (Baldwin, in press). Based on these findings, we hypothesized that increasing the amplitude of verbal material would improve working memory efficiency. RESULTS In support of this hypothesis, a strong positive correlation between the amplitude level at which the verbal material was presented and complex working memory span as measured by a version of Daneman and Carpenter’s (1980) Listening span task was observed. This positive relationshi

    X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180

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    The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days with ASCA and RXTE (and EUVE for Ton S180). The short time scale (hours-days) variability patterns were very similar across energy bands, with no evidence of lags between any of the energy bands studied. The fractional variability amplitude was almost independent of energy band. It is difficult to simultaneously explain soft Seyferts stronger variability, softer spectra, and weaker energy-dependence of the variability relative to hard Seyferts. The soft and hard band light curves diverged on the longest time scales probed, consistent with the fluctuation power density spectra that showed relatively greater power on long time scales in the softest bands. The simplest explanation is that a relatively hard, rapidly-variable component dominates the total X-ray spectrum and a slowly-variable soft excess is present in the lowest energy channels of ASCA. Although it would be natural to identify the latter with an accretion disk and the former with a corona surrounding it, a standard thin disk could not get hot enough to radiate significantly in the ASCA band, and the observed variability time scales are much too short. The hard component may have a more complex shape than a pure power-law. The most rapid factor of 2 flares and dips occurred within ~1000 sec in Ark 564 and a bit more slowly in Ton S180. The speed of the luminosity changes rules out viscous or thermal processes and limits the size of the individual emission regions to <~15 Schwarzschild radii (and probably much less), that is, to either the inner disk or small regions in a corona

    XO-2b: a hot Jupiter with a variable host star that potentially affects its measured transit depth

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    The transiting hot Jupiter XO-2b is an ideal target for multi-object photometry and spectroscopy as it has a relatively bright (VV-mag = 11.25) K0V host star (XO-2N) and a large planet-to-star contrast ratio (Rp_{p}/Rs0.015_{s}\approx0.015). It also has a nearby (31.21") binary stellar companion (XO-2S) of nearly the same brightness (VV-mag = 11.20) and spectral type (G9V), allowing for the characterization and removal of shared systematic errors (e.g., airmass brightness variations). We have therefore conducted a multiyear (2012--2015) study of XO-2b with the University of Arizona's 61" (1.55~m) Kuiper Telescope and Mont4k CCD in the Bessel U and Harris B photometric passbands to measure its Rayleigh scattering slope to place upper limits on the pressure-dependent radius at, e.g., 10~bar. Such measurements are needed to constrain its derived molecular abundances from primary transit observations. We have also been monitoring XO-2N since the 2013--2014 winter season with Tennessee State University's Celestron-14 (0.36~m) automated imaging telescope to investigate stellar variability, which could affect XO-2b's transit depth. Our observations indicate that XO-2N is variable, potentially due to {cool star} spots, {with a peak-to-peak amplitude of 0.0049±0.00070.0049 \pm 0.0007~R-mag and a period of 29.89±0.1629.89 \pm 0.16~days for the 2013--2014 observing season and a peak-to-peak amplitude of 0.0035±0.00070.0035 \pm 0.0007~R-mag and 27.34±0.2127.34 \pm 0.21~day period for the 2014--2015 observing season. Because of} the likely influence of XO-2N's variability on the derivation of XO-2b's transit depth, we cannot bin multiple nights of data to decrease our uncertainties, preventing us from constraining its gas abundances. This study demonstrates that long-term monitoring programs of exoplanet host stars are crucial for understanding host star variability.Comment: published in ApJ, 9 pages, 11 figures, 3 tables; updated figures with more ground-based monitoring, added more citations to previous work

    Interferometry of ϵ\epsilon Aurigae: Characterization of the asymmetric eclipsing disk

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    We report on a total of 106 nights of optical interferometric observations of the ϵ\epsilon Aurigae system taken during the last 14 years by four beam combiners at three different interferometric facilities. This long sequence of data provides an ideal assessment of the system prior to, during, and after the recent 2009-2011 eclipse. We have reconstructed model-independent images from the 10 in-eclipse epochs which show that a disk-like object is indeed responsible for the eclipse. Using new 3D, time-dependent modeling software, we derive the properties of the F-star (diameter, limb darkening), determine previously unknown orbital elements (Ω\Omega, ii), and access the global structures of the optically thick portion of the eclipsing disk using both geometric models and approximations of astrophysically relevant density distributions. These models may be useful in future hydrodynamical modeling of the system. Lastly, we address several outstanding research questions including mid-eclipse brightening, possible shrinking of the F-type primary, and any warps or sub-features within the disk.Comment: 105 pages, 57 figures. This is an author-created, un-copyedited version of an article accepted for publication in Astrophysical Journal Supplement Series. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

    Standardized Patient Encounters Periodic Versus Postencounter Evaluation of Nontechnical Clinical Performance

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    Introduction: Standardized patients are a beneficial component of modern healthcare education and training, but few studies have explored cognitive factors potentially impacting clinical skills assessment during standardized patient encounters. This study examined the impact of a periodic (vs. traditional postencounter) evaluation approach and the appearance of critical verbal and nonverbal behaviors throughout a standardized patient encounter on scoring accuracy in a video-based scenario. Methods: Forty-nine standardized patients scored either periodically or at only 1 point in time (postencounter) a healthcare provider\u27s verbal and nonverbal clinical performance during a videotaped standardized patient encounter. The healthcare provider portrayed in this study was actually a standardized patient delivering carefully scripted verbal and nonverbal behaviors in their portrayal of an actual physician. The encounter itself was subdivided into 3 distinct segments for the purpose of supporting periodic evaluation, with the expectation that both verbal and nonverbal cues occurring in the middle segment would be more challenging to accurately report for participants in the postscenario evaluation group as a result of working memory decay. Results: Periodic evaluators correctly identified a significantly greater number of critical verbal cues midscenario than postencounter evaluators (P \u3c 0.01) and correctly identified a significantly greater number of critical nonverbal cues than their postscenario counterparts across all 3 scenario segments (P \u3c 0.001). Further, postscenario evaluations exhibited a performance decrement in terms of midscenario correct identifications that periodic evaluators did not (P \u3c 0.01). Also, periodic evaluators exhibited fewer verbal cue false-positives during the first segment of the scenario than postscenario evaluators (P \u3c 0.001), but this effect did not extend to other segments regardless of the cue type (ie, verbal or nonverbal). Discussion: Pausing lengthier standardized patient encounters periodically to allow for more frequent scoring may result in better reporting accuracy for certain clinical behavioral cues. This could enable educators to provide more specific formative feedback to individual learners at the session\u27s conclusion. The most effective encounter design will ultimately depend on the specific goals and training objectives of the exercise itself
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