355 research outputs found

    The FLASHES Survey I: Integral Field Spectroscopy of the CGM around 48 z=2.33.1z=2.3-3.1 QSOs

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    We present the pilot study component of the Fluorescent Lyman-Alpha Structures in High-z Environments (FLASHES) Survey; the largest integral-field spectroscopy survey to date of the circumgalactic medium at z=2.33.1z=2.3-3.1. We observed 48 quasar fields between 2015 and 2018 with the Palomar Cosmic Web Imager (Matuszewski et al. 2010). Extended HI Lyman-α\mathrm{\alpha} emission is discovered around 42/48 of the observed quasars, ranging in projected, flux-weighted radius from 21-71 proper kiloparsecs (pkpc), with 26 nebulae exceeding 100 pkpc100\mathrm{~pkpc} in effective diameter. The circularly averaged surface brightness radial profile peaks at a maximum of 1×1017 erg s1 cm2 arcsec2\mathrm{1\times 10^{-17}~erg~s^{-1}~cm^{-2}~arcsec^{-2}} (2×1015 erg s1 cm2 arcsec22\times10^{-15}~\mathrm{erg~s^{-1}~cm^{-2}~arcsec^{-2}} adjusted for cosmological dimming) and luminosities range from 1.9×1043 erg s11.9\times10^{43}~\mathrm{erg~s^{-1}} to 14.1×1043 erg s1-14.1\times10^{43}~\mathrm{erg~s^{-1}}. The emission appears to have a highly eccentric morphology and a maximum covering factor of 50%50\% (60%60\% for giant nebulae). On average, the nebular spectra are red-shifted with respect to both the systemic redshift and Lyα\alpha peak of the quasar spectrum. The integrated spectra of the nebulae mostly have single or double-peaked line shapes with global dispersions ranging from 167 km s1167~\mathrm{km~s^{-1}} to 690 km s1690~\mathrm{km~s^{-1}}, though the individual (Gaussian) components of lines with complex shapes mostly appear to have dispersions 400\leq 400 km s1\mathrm{km~s^{-1}}, and the flux-weighted velocity centroids of the lines vary by thousands of km s1 \mathrm{km~s^{-1}} with respect to the systemic QSO redshifts. Finally, the root-mean-square velocities of the nebulae are found to be consistent with gravitational motions expected in dark matter halos of mass Mh1012.5M\mathrm{M_h \simeq10^{12.5} M_\odot}. We compare these results to existing surveys at both higher and lower redshift

    Simulated LSST Survey of RR Lyrae Stars throughout the Local Group

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    We report on a study to determine the efficiency of the Large Synoptic Survey Telescope (LSST) to recover the periods, brightnesses, and shapes of RR Lyrae stars' light curves in the volume extending to heliocentric distances of 1.5 Mpc. We place the smoothed light curves of 30 type ab and 10 type c RR Lyrae stars in 1007 fields across the sky, each of which represents a different realization of the LSST sampling cadences, and that sample five particular observing modes. A light curve simulation tool was used to sample the idealized RR Lyrae stars' light curves, returning each as it would have been observed by LSST, including realistic photometric scatter, limiting magnitudes, and telescope downtime. We report here the period, brightness, and light curve shape recovery as a function of apparent magnitude and for survey lengths varying from 1 to 10 years. We find that 10 years of LSST data are sufficient to recover the pulsation periods with a fractional precision of ~10^(–5) for ≥90% of ab stars within ≈360 kpc of the Sun in Universal Cadence fields and out to ≈760 kpc for Deep Drilling fields. The 50% completeness level extends to ≈600 kpc and ≈1.0 Mpc for the same fields, respectively. For virtually all stars that had their periods recovered, their light curve shape parameter φ_31 was recovered with sufficient precision to also recover photometric metallicities to within 0.14 dex (the systematic error in the photometric relations). With RR Lyrae stars' periods and metallicities well measured to these distances, LSST will be able to search for halo streams and dwarf satellite galaxies over half of the Local Group, informing galaxy formation models and providing essential data for mapping the Galactic potential. This study also informs the LSST science operations plan for optimizing observing strategies to achieve particular science goals. We additionally present a new [Fe/H]-φ_31 photometric relation in the r band and a new and generally useful metric for defining period recovery for time domain surveys

    FIREBall-2: advancing TRL while doing proof-of-concept astrophysics on a suborbital platform

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    Here we discuss advances in UV technology over the last decade, with an emphasis on photon counting, low noise, high efficiency detectors in sub-orbital programs. We focus on the use of innovative UV detectors in a NASA astrophysics balloon telescope, FIREBall-2, which successfully flew in the Fall of 2018. The FIREBall-2 telescope is designed to make observations of distant galaxies to understand more about how they evolve by looking for diffuse hydrogen in the galactic halo. The payload utilizes a 1.0-meter class telescope with an ultraviolet multi-object spectrograph and is a joint collaboration between Caltech, JPL, LAM, CNES, Columbia, the University of Arizona, and NASA. The improved detector technology that was tested on FIREBall-2 can be applied to any UV mission. We discuss the results of the flight and detector performance. We will also discuss the utility of sub-orbital platforms (both balloon payloads and rockets) for testing new technologies and proof-of-concept scientific ideas

    The Changing Role of Digital Tools and Academic Libraries in Scholarly Workflows: A Review

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    In this paper, we review the literature on how information literacies are manifested in scholarly workflows for undergraduates, graduate students, and scholars, and the need to support integrating library resources into their knowledge practices, and how available tools support their needs. We argue that research is needed on how libraries and digital tools both support, and indeed teach, knowledge-building practices across the entire lifecycle of knowledge. Finally, we advocate for studying researcher and student workflows as a way to both improve the tools we make available, and more importantly, to inform us on the role(s) libraries can play in the shifting practices of research in an information-rich world

    The role of libraries in teaching doctoral students to become information-literate researchers:A review of existing practices and recommendations for the future

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    Purpose This paper aims to review current literature pertaining to information literacy and digital literacy skills and practices within the research workflow for doctoral students and makes recommendations for how libraries (and others) can foster skill-sets for graduate student research workflows for the twenty-first century scholarly researcher. Design/methodology/approach A review of existing information literacy practices for doctoral students was conducted, and four key areas of knowledge were identified and discussed. Findings The findings validate the need for graduate students to have training in information literacy, information management, knowledge management and scholarly communication. It recommends empirical studies to be conducted to inform future practices for doctoral students. Practical implications This paper offers four areas of training to be considered by librarians and faculty advisers to better prepare scholars for their future. Originality/value This paper presents a distinctive synthesis of the types of information literacy and digital literacy skills needed by graduate students

    Intratumor Heterogeneity of the Estrogen Receptor and the Long-term Risk of Fatal Breast Cancer.

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    Background:Breast cancer patients with estrogen receptor (ER)-positive disease have a continuous long-term risk for fatal breast cancer, but the biological factors influencing this risk are unknown. We aimed to determine whether high intratumor heterogeneity of ER predicts an increased long-term risk (25 years) of fatal breast cancer. Methods:The STO-3 trial enrolled 1780 postmenopausal lymph node-negative breast cancer patients randomly assigned to receive adjuvant tamoxifen vs not. The fraction of cancer cells for each ER intensity level was scored by breast cancer pathologists, and intratumor heterogeneity of ER was calculated using Rao's quadratic entropy and categorized into high and low heterogeneity using a predefined cutoff at the second tertile (67%). Long-term breast cancer-specific survival analyses by intra-tumor heterogeneity of ER were performed using Kaplan-Meier and multivariable Cox proportional hazard modeling adjusting for patient and tumor characteristics. Results:A statistically significant difference in long-term survival by high vs low intratumor heterogeneity of ER was seen for all ER-positive patients (P < .001) and for patients with luminal A subtype tumors (P = .01). In multivariable analyses, patients with high intratumor heterogeneity of ER had a twofold increased long-term risk as compared with patients with low intratumor heterogeneity (ER-positive: hazard ratio [HR] = 1.98, 95% confidence interval [CI] = 1.31 to 3.00; luminal A subtype tumors: HR = 2.43, 95% CI = 1.18 to 4.99). Conclusions:Patients with high intratumor heterogeneity of ER had an increased long-term risk of fatal breast cancer. Interestingly, a similar long-term risk increase was seen in patients with luminal A subtype tumors. Our findings suggest that intratumor heterogeneity of ER is an independent long-term prognosticator with potential to change clinical management, especially for patients with luminal A tumors

    Comparison of Airborne and Ground-Based Function Allocation Concepts for NextGen Using Human-In-The-Loop Simulations

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    This paper presents an air/ground functional allocation experiment conducted by the National Aeronautics and Space Administration (NASA) using two human-in-the-Loop simulations to compare airborne and ground-based approaches to NextGen separation assurance. The approaches under investigation are two trajectory-based four-dimensional (4D) concepts; one referred to as "airborne trajectory management with self-separation" (airborne) the other as "ground-based automated separation assurance" (ground-based). In coordinated simulations at NASA's Ames and Langley Research Centers, the primary operational participants -controllers for the ground-based concept and pilots for the airborne concept - manage the same traffic scenario using the two different 4D concepts. The common scenarios are anchored in traffic problems that require a significant increase in airspace capacity - on average, double, and in some local areas, close to 250% over current day levels - in order to enable aircraft to safely and efficiently traverse the test airspace. The simulations vary common independent variables such as traffic density, sequencing and scheduling constraints, and timing of trajectory change events. A set of common metrics is collected to enable a direct comparison of relevant results. The simulations will be conducted in spring 2010. If accepted, this paper will be the first publication of the experimental approach and early results. An initial comparison of safety and efficiency as well as operator acceptability under the two concepts is expected
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