55 research outputs found

    Slit Mask Integral Field Units for the Southern African Large Telescope

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    Two fibre integral field units (IFU) are being built in the SAAO fibre-lab for the Robert Stobie Spectrograph's visible arm and the future red arm. Each IFU sits in its own slit-mask cassette and is referred to as a slit-mask IFU (SMI). They will be available some time in 2022. The smaller, 200 micron fibre IFU has 309 X 0.9 arcsec diameter spatial elements covering an elongated hexagonal footprint of 18 X 23 arcsec. The larger, 400 micron fibre IFU has 178 X 1.8 arcsec diameter spatial elements covering an on-sky area of 21 X 44 arcsec. In both cases there are two groups of 13 fibres offset by roughly 50 arcsec on either side of the primary array to sample sky. The 1.8 and 0.9 arcsec spatial resolution SMIs provide median spectral resolution of 1200 and 2400 respectively at H alpha wavelengths in the low resolution mode covering 320 to 740 nm bandpass. At a higher grating angle the SMI will deliver spectral resolution up to 5000 and 10000 with 400 and 200 micron core fibre respectively. A future red-arm will extend the simultaneous wavelength coverage up to 900 nm at a median resolution of 3000/6000 for the same flavors of IFUs. SMIs are inserted in the same fashion as the existing longslit cassettes at the SALT focal plane. Prismatic fold mirrors direct the focal plane into the fibre IFU and then back into the RSS collimator after the fibres are routed 180 deg within the cassette and formatted into a pseudo-slit. Fold prisms ensure that the spectrograph collimator continues to see the same focal plane. In this paper we describe the design, fabrication, assembly and characterization of Slit Mask IFUs

    Predictors of Occupational Competence in People Hospitalized with Chronic Conditions

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    Background: Chronic diseases limit participation in meaningful daily activities, roles, and routines, which can negatively impact occupational competence, a sense of self, and life satisfaction, especially when hospitalization is required to manage disease symptoms. Standardized measures of occupational competence and related functional, cognitive, and environmental factors may enhance occupational therapists’ ability to identify potential barriers to and make targeted recommendations for self- and health management in the community. Method: This cross-sectional study investigated occupational competence in patients hospitalized with chronic conditions. The participants completed measures of occupational competence, values, self-care function, environmental impact, and functional cognition while hospitalized. Results: The participants (n = 51) reported moderate to high levels of occupational competence. The overall regression model was significant. Values, self-care function, and environmental impact were significant predictors of occupational competence. Conclusion: Values, self-care function, and environmental impact predict occupational competence in people hospitalized with chronic conditions. Occupational therapists should incorporate standardized measures of occupational competence, values, self-care function, and environmental impact into current evaluation practices to support recommendations for follow-up care and community supports. Future research should include a larger sample that is more representative of an occupational therapy caseload and incorporate alternative measures of functional cognition to better measure this construct

    Predictors of Hospital Readmissions for People with Chronic Conditions

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    Background: Hospital readmissions remain prominent in health care. Functional, cognitive, and environmental factors predict hospital readmissions but may not be thoroughly measured or addressed prior to discharge. Method: In this cross-sectional study, people hospitalized with chronic conditions completed measures of self-care function, functional cognition, occupational competence, and environmental impact. They also participated in a phone call or medical records review to identify hospital readmissions within 30 days of discharge. In a group session, occupational therapists who work in acute care completed acceptability, appropriateness, and feasibility measures for the standardized assessments administered to hospital participants. Results: Occupational competence and functional cognition were significant predictors of hospital readmissions. Therapists rated the Activity Measure of Post-Acute Care (AM-PAC) as the most acceptable, appropriate, and feasible measure for acute care. Conclusions: Occupational competence and functional cognition are predictors of hospital readmissions in people with chronic conditions. Occupational therapists in acute care should consider supplementing current evaluation practices with standardized measures of functional cognition and occupational competence to identify client needs objectively and initiate post-acute referrals that help clients discharge home successfully. Standardized measures, such as the AM-PAC may be feasible in acute care. Further research on the efficacy of standardized measures in this setting is needed

    HexPak and GradPak: variable-pitch dual-head IFUs for the WIYN 3.5m Telescope Bench Spectrograph

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    We describe the design, construction, and expected performance of two new fiber integral field units (IFUs) --- HexPak and GradPak --- for the WIYN 3.5m Telescope Nasmyth focus and Bench Spectrograph. These are the first IFUs to provide formatted fiber integral field spectroscopy with simultaneous sampling of varying angular scales. HexPak and GradPak are in a single cable with a dual-head design, permitting easy switching between the two different IFU heads on the telescope without changing the spectrograph feed: the two heads feed a variable-width double-slit. Each IFU head is comprised of a fixed arrangement of fibers with a range of fiber diameters. The layout and diameters of the fibers within each array are scientifically-driven for observations of galaxies: HexPak is designed to observe face-on spiral or spheroidal galaxies while GradPak is optimized for edge-on studies of galaxy disks. HexPak is a hexagonal array of 2.9 arcsec fibers subtending a 40.9 arcsec diameter, with a high-resolution circular core of 0.94 arcsec fibers subtending 6 arcsec diameter. GradPak is a 39 by 55 arcsec rectangular array with rows of fibers of increasing diameter from angular scales of 1.9 arcsec to 5.6 arcsec across the array. The variable pitch of these IFU heads allows for adequate sampling of light profile gradients while maintaining the photon limit at different scales.Comment: 10 pages, 4 figures, presented at SPIE, Astronomical Telescopes and Instrumentation, 1 - 6 July 2012, Amsterdam, Netherland

    Development and Characterization of a Precisely Adjustable Fiber Polishing Arm

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    The development of bare fiber or air-gapped microlens-fiber coupled Integral Field Units (IFUs) for astronomical applications requires careful treatment of the fiber end-faces (terminations). Previous studies suggest that minimization of fiber end face irregularity leads to better optical performance in terms of the diminishing effect of focal ratio degradation. Polishing has typically been performed using commercial rotary polishers with multiple gradually decreasing grit sizes. These polishers generally lack the ability to carefully adjust angular position and polishing force. Control of these parameters vastly help in getting a repeatable and controllable polish over a variety of glass/epoxy/metal matrices that make up integral filed units and fiber slits. A polishing arm is developed to polish the fiber terminations (IFU, mini-bundles and v-grooves) of the NIR Fiber System for the RSS spectrograph at SALT. The polishing arm angular adjustments ensure the correct position and orientation of each termination on the polishing surface during the polish. Various studies have indicated that the fiber focal ratio also degrades if the fiber end face comes under excessive stress. The polishing arm is fitted with a load cell to enable control of the polishing force. We have explored the minimal applicable end stress by applying different loads while polishing. The arm is modular to hold a variety of fiber termination styles. The polishing arm is also designed to access a fiber inspection microscope without removing the fiber termination from the arm. This enables inspection of the finish quality at various stages through polishing process

    The NIR Upgrade to the SALT Robert Stobie Spectrograph

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    The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT), RSS/NIR, extends the spectral coverage of all modes of the visible arm. The RSS/NIR is a low to medium resolution spectrograph with broadband imaging, spectropolarimetric, and Fabry-Perot imaging capabilities. The visible and NIR arms can be used simultaneously to extend spectral coverage from approximately 3200 A to 1.6 um. Both arms utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera is designed around a 2048x2048 HAWAII-2RG detector housed in a cryogenic dewar. The Epps optical design of the camera consists of 6 spherical elements, providing sub-pixel rms image sizes of 7.5 +/- 1.0 um over all wavelengths and field angles. The exact long wavelength cutoff is yet to be determined in a detailed thermal analysis and will depend on the semi-warm instrument cooling scheme. Initial estimates place instrument limiting magnitudes at J = 23.4 and H(1.4-1.6 um) = 21.6 for S/N = 3 in a 1 hour exposure well below the sky noise.Comment: 12 pages, 10 figures, presented at SPIE, Astronomical Telescopes and Instrumentation, 24 - 31 May 2006, Orlando, Florida US

    G515, Revisited. I. Stellar Populations And Evidence Of Nuclear Activity In A Luminous "E+A" Galaxy

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    We present multiwavelength observations of the very luminous "E+A" galaxy known as G515 (J152426.55+080906.7), including deep K_s imaging, spatially resolved H-alpha spectroscopy, and radio observations. The data, together with detailed spectral synthesis of the galaxy's integrated stellar population, show that G515 is a ~1 Gyr old post-merger, post-starburst galaxy. We detect no Balmer line emission in the galaxy, although there is a small amount of [NII]6548,6583A emission. The galaxy's H I mass has a 2-sigma upper limit of 1.0 * 10^9 solar masses. IRAS detections in the 60-micron and 100-micron bands indicate a far infrared luminosity of ~5.8 * 10^10 solar luminosities. A small amount (~3 mJy) of radio continuum flux, which appears to be variable, has been detected. The data suggest that G515 may have once been an ultraluminous infrared galaxy, and may harbor a weak, dust-obscured active nucleus.Comment: 25 pages, 7 figures, accepted to Ap

    Solar Contamination in Extreme-precision Radial-velocity Measurements: Deleterious Effects and Prospects for Mitigation

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    Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ~10 cm s−1 sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s−1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments

    Which outcome domains are important in palliative care and when? An international expert consensus workshop, using the nominal group technique

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    © The Author(s) 2019. Background: When capturing patient-level outcomes in palliative care, it is essential to identify which outcome domains are most important and focus efforts to capture these, in order to improve quality of care and minimise collection burden. Aim: To determine which domains of palliative care are most important for measurement of outcomes, and the optimal time period over which these should be measured. Design: An international expert consensus workshop using nominal group technique. Data were analysed descriptively, and weighted according to ranking (1–5, lowest to highest priority) of domains. Participants’ rationales for their choices were analysed thematically. Setting/participants: In all, 33 clinicians and researchers working globally in palliative care outcome measurement participated. Two groups (n = 16; n = 17) answered one question each (either on domains or optimal timing). This workshop was conducted at the 9th World Research Congress of the European Association for Palliative Care in 2016. Results: Participants’ years of experience in palliative care and in outcome measurement ranged from 10.9 to 14.7 years and 5.8 to 6.4 years, respectively. The mean scores (weighted by rank) for the top-ranked domains were ‘overall wellbeing/quality of life’ (2.75), ‘pain’ (2.06), and ‘information needs/preferences’ (2.06), respectively. The palliative measure ‘Phase of Illness’ was recommended as the preferred measure of time period over which the domains were measured. Conclusion: The domains of ‘overall wellbeing/quality of life’, ‘pain’, and ‘information needs/preferences’ are recommended for regular measurement, assessed using ‘Phase of Illness’. International adoption of these recommendations will help standardise approaches to improving the quality of palliative care

    The NEID Precision Radial Velocity Spectrometer: Port Adapter Overview, Requirements, and Test Plan

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    The NEID spectrometer is an optical (380-930 nm), fiber-fed, precision Doppler spectrometer currently in development for the WIYN 3.5 m telescope at Kitt Peak National Observatory as part of the NN-EXPLORE partnership. Designed to achieve a radial velocity precision of < 30 cm/s, NEID will be sensitive enough to detect terrestrial-mass exoplanets around low-mass stars. Light from the target stars is focused by the telescope to a bent Cassegrain port at the edge of the primary mirror mechanical support. The specialized NEID "Port Adapter" system is mounted at this bent Cassegrain port and is responsible for delivering the incident light from the telescope to the NEID fibers. In order to provide stable, high-quality images to the science instrument, the Port Adapter houses several sub-components designed to acquire the target stars, correct for atmospheric dispersion, stabilize the light onto the science fibers, and calibrate the spectrometer by injecting known wavelength sources such as a laser frequency comb. Here we provide an overview of the overall opto-mechanical design and system requirements of the Port Adapter. We also describe the development of system error budgets and testplans to meet those requirements
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