1,397 research outputs found

    The H-alpha Luminosity Function and Star Formation Rate Volume Density at z=0.8 from the NEWFIRM H-alpha Survey

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    [Abridged] We present new measurements of the H-alpha luminosity function (LF) and SFR volume density for galaxies at z~0.8. Our analysis is based on 1.18μ\mum narrowband data from the NEWFIRM H-alpha Survey, a comprehensive program designed to capture deep samples of intermediate redshift emission-line galaxies using narrowband imaging in the near-infrared. The combination of depth (1.9×1017\approx1.9\times10^{-17} erg s1^{-1} cm2^{-2} in H-alpha at 3σ\sigma) and areal coverage (0.82 deg2^2) complements other recent H-alpha studies at similar redshifts, and enables us to minimize the impact of cosmic variance and place robust constraints on the shape of the LF. The present sample contains 818 NB118 excess objects, 394 of which are selected as H-alpha emitters. Optical spectroscopy has been obtained for 62% of the NB118 excess objects. Empirical optical broadband color classification is used to sort the remainder of the sample. A comparison of the LFs constructed for the four individual fields reveals significant cosmic variance, emphasizing that multiple, widely separated observations are required. The dust-corrected LF is well-described by a Schechter function with L*=10^{43.00\pm0.52} ergs s^{-1}, \phi*=10^{-3.20\pm0.54} Mpc^{-3}, and \alpha=-1.6\pm0.19. We compare our H-alpha LF and SFR density to those at z<1, and find a rise in the SFR density \propto(1+z)^{3.4}, which we attribute to significant L* evolution. Our H-alpha SFR density of 10^{-1.00\pm0.18} M_sun yr^{-1} Mpc^{-3} is consistent with UV and [O II] measurements at z~1. We discuss how these results compare to other H-alpha surveys at z~0.8, and find that the different methods used to determine survey completeness can lead to inconsistent results. This suggests that future surveys probing fainter luminosities are needed, and more rigorous methods of estimating the completeness should be adopted as standard procedure.Comment: 19 pages (emulate-ApJ format), 16 figures, 5 tables, published in ApJ. Modified to match ApJ versio

    The H-alpha Luminosity Function and Star Formation Rate Volume Density at z=0.8 from the NEWFIRM H-alpha Survey

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    [Abridged] We present new measurements of the H-alpha luminosity function (LF) and SFR volume density for galaxies at z~0.8. Our analysis is based on 1.18μ\mum narrowband data from the NEWFIRM H-alpha Survey, a comprehensive program designed to capture deep samples of intermediate redshift emission-line galaxies using narrowband imaging in the near-infrared. The combination of depth (1.9×1017\approx1.9\times10^{-17} erg s1^{-1} cm2^{-2} in H-alpha at 3σ\sigma) and areal coverage (0.82 deg2^2) complements other recent H-alpha studies at similar redshifts, and enables us to minimize the impact of cosmic variance and place robust constraints on the shape of the LF. The present sample contains 818 NB118 excess objects, 394 of which are selected as H-alpha emitters. Optical spectroscopy has been obtained for 62% of the NB118 excess objects. Empirical optical broadband color classification is used to sort the remainder of the sample. A comparison of the LFs constructed for the four individual fields reveals significant cosmic variance, emphasizing that multiple, widely separated observations are required. The dust-corrected LF is well-described by a Schechter function with L*=10^{43.00\pm0.52} ergs s^{-1}, \phi*=10^{-3.20\pm0.54} Mpc^{-3}, and \alpha=-1.6\pm0.19. We compare our H-alpha LF and SFR density to those at z<1, and find a rise in the SFR density \propto(1+z)^{3.4}, which we attribute to significant L* evolution. Our H-alpha SFR density of 10^{-1.00\pm0.18} M_sun yr^{-1} Mpc^{-3} is consistent with UV and [O II] measurements at z~1. We discuss how these results compare to other H-alpha surveys at z~0.8, and find that the different methods used to determine survey completeness can lead to inconsistent results. This suggests that future surveys probing fainter luminosities are needed, and more rigorous methods of estimating the completeness should be adopted as standard procedure.Comment: 19 pages (emulate-ApJ format), 16 figures, 5 tables, published in ApJ. Modified to match ApJ versio

    New portable tool to screen vestibular and visual function—National Institutes of Health Toolbox initiative

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    As part of the National Institutes of Health Toolbox initiative, we developed a low-cost, easy-to-administer, and time-efficient test of vestibular and visual function. A computerized test of dynamic visual acuity (cDVA) was used to measure the difference in visual acuity between head still and moving in yaw. Participants included 318 individuals, aged 3 to 85 years (301 without and 17 with vestibular pathology). Adults used Early Treatment of Diabetic Retinopathy Study (ETDRS) optotypes; children used ETDRS, Lea, and HOTV optotypes. Bithermal calorics, rotational chair, and light box testing were used to validate the cDVA. Analysis revealed that the cDVA test is reliable for static (intraclass correlation coefficient [ICC] \u3e/= 0.64) and dynamic (ICC \u3e/= 0.43–0.75) visual acuity. Children younger than 6 years old were more likely to complete cDVA with Lea optotypes, but reliability and correlation with ETDRS was better using HOTV optotypes. The high correlation between static acuity and light box test scores (r = 0.795), significant difference of cDVA scores between those with and without pathology (

    The employee as 'Dish of the Day’:human resource management and the ethics of consumption

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    This article examines the ethical implications of the growing integration of consumption into the heart of the employment relationship. Human resource management (HRM) practices increasingly draw upon the values and practices of consumption, constructing employees as the ‘consumers’ of ‘cafeteria-style’ benefits and development opportunities. However, at the same time employees are expected to market themselves as items to be consumed on a corporate menu. In relation to this simultaneous position of consumer/consumed, the employee is expected to actively engage in the commodification of themselves, performing an appropriate organizational identity as a necessary part of being a successful employee. This article argues that the relationship between HRM and the simultaneously consuming/consumed employee affects the conditions of possibility for ethical relations within organizational life. It is argued that the underlying ‘ethos’ for the integration of consumption values into HRM practices encourages a self-reflecting, self-absorbed subject, drawing upon a narrow view of individualised autonomy and choice. Referring to Levinas’ perspective that the primary ethical relation is that of responsibility and openness to the Other, it is concluded that these HRM practices affect the possibility for ethical being

    Nebular Attenuation in H\alpha-selected Star-forming Galaxies at z=0.8 from the NewH\alpha\ Survey

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    We present measurements of the dust attenuation of H\alpha-selected emission-line galaxies at z=0.8 from the NewH\alpha\ narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong rest-frame optical emission lines from [OII] \lambda 3727 to [OIII] \lambda 5007. The spectroscopic sample used in this analysis consists of 341 confirmed H\alpha\ emitters. We place constraints on the AGN fraction using diagnostics which can be applied at intermediate redshift. We find that at least 5% of the objects in our spectroscopic sample can be classified as AGN and 2% are composite, i.e. powered by a combination of star-formation and AGN activity. We measure the dust attenuation for individual objects from the ratios of the higher order Balmer lines. The H\beta\ and H\gamma\ pair of lines is detected with S/N>5 in 55 individual objects and the H\beta\ and H\delta\ pair is detected in 50 individual objects. We also create stacked spectra to probe the attenuation in objects without individual detections. The median attenuation at H\alpha\ based on the objects with individually detected lines is A(H\alpha)=0.9+-1.0 magnitudes, in good agreement with the attenuation found in local samples of star-forming galaxies. We find that the z=0.8 galaxies occupy a similar locus of attenuation as a function of magnitude, mass and SFR as a comparison sample drawn from the SDSS DR4. Both the results from the individual z=0.8 galaxies and from the stacked spectra show consistency with the mass -- attenuation and SFR -- attenuation relations found in the local Universe, indicating that these relations are also applicable at intermediate redshift.Comment: Submitted to AJ. Revised per referee's comment

    Performance of Landscape Plants from Northern Japan in the North Central United States

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    In 1984 and 1985, 21 landscape plant introductions from northern Japan were distributed for testing in the NC-7 Regional Ornamental Plant Trials. Seventeen of these introductions were evaluated for 10 years at six to ten sites representing a cross-section of growing conditions in the north central United States. For these 17 introductions, first-year survival averaged 60%; however, by year 10, fewer than 20% of the original 425 plants were alive. Based on these evaluations, the populations could be divided into four groups. One population of Rosa rugosa was adapted to most trial sites; two populations (Alnus hirsuta and Lonicera chrysantha) were adapted to some sites; three populations were of poorly adapted dieback shrubs, and the remaining II populations included a diverse set of trees and shrubs unadapted to any, or nearly any, trial site. Temperature and moisture data from Japan and from trial sites were used to examine relationships between plant adaptation and climate. Statistically significant, multiple-regression models were calculated to describe the functional relationships between temperature and moisture conditions and plant adaptation at the various trial sites. Our models predict that plants from northern Japan are best adapted to sites in the northeastern United States where moisture surpluses exceed those typically found in the north central United States. These models also suggest criteria to evaluate sites throughout northeastern Asia for future exploration
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