948 research outputs found

    User observations on information sharing (corporate knowledge and lessons learned)

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    The sharing of 'corporate knowledge' and lessons learned in the NASA aerospace community has been identified by Johnson Space Center survey participants as a desirable tool. The concept of the program is based on creating a user friendly information system that will allow engineers, scientists, and managers at all working levels to share their information and experiences with other users irrespective of location or organization. The survey addresses potential end uses for such a system and offers some guidance on the development of subsequent processes to ensure the integrity of the information shared. This system concept will promote sharing of information between NASA centers, between NASA and its contractors, between NASA and other government agencies, and perhaps between NASA and institutions of higher learning

    Mott Transition in Degenerate Hubbard Models: Application to Doped Fullerenes

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    The Mott-Hubbard transition is studied for a Hubbard model with orbital degeneracy N, using a diffusion Monte-Carlo method. Based on general arguments, we conjecture that the Mott-Hubbard transition takes place for U/W \propto \sqrt{N}, where U is the Coulomb interaction and W is the band width. This is supported by exact diagonalization and Monte-Carlo calculations. Realistic parameters for the doped fullerenes lead to the conclusion that stoichiometric A_3 C_60 (A=K, Rb) are near the Mott-Hubbard transition, in a correlated metallic state.Comment: 4 pages, revtex, 1 eps figure included, to be published in Phys.Rev.B Rapid Com

    The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples

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    We explore the cosmological implications of the angle-averaged correlation function, ξ(s), and the clustering wedges, ξ⊥(s) and ξ∥(s), of the LOWZ and CMASS galaxy samples from Data Releases 10 and 11 of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation from the standard Λ cold dark matter model. The combination of the information from our clustering measurements with recent data from the cosmic microwave background is sufficient to constrain the curvature of the Universe to Ωk = 0.0010 ± 0.0029, the total neutrino mass to ∑mν < 0.23 eV (95 per cent confidence level), the effective number of relativistic species to Neff = 3.31 ± 0.27 and the dark energy equation of state to wDE = −1.051 ± 0.076. These limits are further improved by adding information from Type Ia supernovae and baryon acoustic oscillations from other samples. In particular, this data set combination is completely consistent with a time-independent dark energy equation of state, in which case we find wDE = −1.024 ± 0.052. We explore the constraints on the growth rate of cosmic structures assuming f(z) = Ωm(z)γ and obtain γ = 0.69 ± 0.15, consistent with the predictions of general relativity of γ = 0.55.Publisher PDFPeer reviewe

    Anti-Black racism in clinical supervision:asynchronous simulated encounters facilitate reflective practice

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    Background: Racist interactions in clinical practice remain a pervasive reality for Black healthcare providers. We sought to develop a framework to inform supervisors' actions when confronting racism in clinical practice and protecting trainees under their oversight.Methods: We conducted a qualitative study in which experienced supervisors responded to seven short, videotaped interactions between: 1) Black trainees and a simulated patient (SP) in a racist role; 2) the trainees and their respective supervisors; and 3) the trainees and their supervisors together with the SP. The clinical exchanges exemplified different types of racist (entrenching) or antiracist (uprooting) behaviors by the supervisors. After viewing each clip, participants wrote their reflections confidentially; they later joined a structured debriefing together. We used thematic analysis to identify supervisors' behavioral patterns when confronting racist interactions.Results: Based on the input of 52 participants recruited into five two-hour-long sessions, we categorized the behaviors of supervisors facing anti-Black racial injuries involving learners under their oversight. We organized supervisor behaviors into five interlocking domains, each with a range of possible themes: 1) Joining: from conciliatory to confrontational in communicating with the aggressor; 2) Explicitness: from avoiding to naming racism; 3) Ownership: from individual to shared responsibility of the event and the response to it; 4) Involving: from excusing to including the aggrieved party when confronting the aggressor; and 5) Stance: from protective to paternalistic in supporting the learner's autonomy.Conclusions: Our qualitative findings can provide a framework for facilitated discussion toward reflective practice among healthcare providers who may have experienced, witnessed, or intervened in anti-Black racist interactions. They can also help medical educators to inform faculty development to fight anti-Black racism in clinical practice. The video materials we developed are available for viewing and download and can be used or adapted as springboards for reflective discussion or faculty development activities. </p

    The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering

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    With the largest spectroscopic galaxy survey volume drawn from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological constraints from the measurements of redshift and geometric distortions at quasi-linear scales (e.g. above 50 h1h^{-1}Mpc). We analyze the broad-range shape of the monopole and quadrupole correlation functions of the BOSS Data Release 12 (DR12) CMASS galaxy sample, at the effective redshift z=0.59z=0.59, to obtain constraints on the Hubble expansion rate H(z)H(z), the angular-diameter distance DA(z)D_A(z), the normalized growth rate f(z)σ8(z)f(z)\sigma_8(z), and the physical matter density Ωmh2\Omega_mh^2. We obtain robust measurements by including a polynomial as the model for the systematic errors, and find it works very well against the systematic effects, e.g., ones induced by stars and seeing. We provide accurate measurements {DA(0.59)rs,fid/rs\{D_A(0.59)r_{s,fid}/r_s Mpc\rm Mpc, H(0.59)rs/rs,fidH(0.59)r_s/r_{s,fid} kms1Mpc1km s^{-1} Mpc^{-1}, f(0.59)σ8(0.59)f(0.59)\sigma_8(0.59), Ωmh2}\Omega_m h^2\} = {1427±26\{1427\pm26, 97.3±3.397.3\pm3.3, 0.488±0.0600.488 \pm 0.060, 0.135±0.016}0.135\pm0.016\}, where rsr_s is the comoving sound horizon at the drag epoch and rs,fid=147.66r_{s,fid}=147.66 Mpc is the sound scale of the fiducial cosmology used in this study. The parameters which are not well constrained by our galaxy clustering analysis are marginalized over with wide flat priors. Since no priors from other data sets, e.g., cosmic microwave background (CMB), are adopted and no dark energy models are assumed, our results from BOSS CMASS galaxy clustering alone may be combined with other data sets, i.e., CMB, SNe, lensing or other galaxy clustering data to constrain the parameters of a given cosmological model. The uncertainty on the dark energy equation of state parameter, ww, from CMB+CMASS is about 8 per cent. The uncertainty on the curvature fraction, Ωk\Omega_k, is 0.3 per cent. We do not find deviation from flat Λ\LambdaCDM.Comment: 15 pages, 11 figures. The latest version matches and the accepted version by MNRAS. A bug in the first version has been identified and fixed in the new version. We have redone the analysis with newest data (BOSS DR12

    The Green Bank Ammonia Survey (GAS): First Results of NH3 mapping the Gould Belt

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    We present an overview of the first data release (DR1) and first-look science from the Green Bank Ammonia Survey (GAS). GAS is a Large Program at the Green Bank Telescope to map all Gould Belt star-forming regions with AV7A_V \gtrsim 7 mag visible from the northern hemisphere in emission from NH3_3 and other key molecular tracers. This first release includes the data for four regions in Gould Belt clouds: B18 in Taurus, NGC 1333 in Perseus, L1688 in Ophiuchus, and Orion A North in Orion. We compare the NH3_3 emission to dust continuum emission from Herschel, and find that the two tracers correspond closely. NH3_3 is present in over 60\% of lines-of-sight with AV7A_V \gtrsim 7 mag in three of the four DR1 regions, in agreement with expectations from previous observations. The sole exception is B18, where NH3_3 is detected toward ~ 40\% of lines-of-sight with AV7A_V \gtrsim 7 mag. Moreover, we find that the NH3_3 emission is generally extended beyond the typical 0.1 pc length scales of dense cores. We produce maps of the gas kinematics, temperature, and NH3_3 column densities through forward modeling of the hyperfine structure of the NH3_3 (1,1) and (2,2) lines. We show that the NH3_3 velocity dispersion, σv{\sigma}_v, and gas kinetic temperature, TKT_K, vary systematically between the regions included in this release, with an increase in both the mean value and spread of σv{\sigma}_v and TKT_K with increasing star formation activity. The data presented in this paper are publicly available.Comment: 33 pages, 27 figures, accepted to ApJS. Datasets are publicly available: https://dataverse.harvard.edu/dataverse/GAS_DR

    Prevalence of long COVID-19 among healthcare workers: a systematic review and meta-analysis protocol

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    Introduction A proportion of those who survive the acute phase of COVID-19 experience prolonged symptoms, commonly known as long COVID-19. Given that healthcare workers (HCWs) face an elevated risk of acute COVID-19 compared with the general population, the global burden of long COVID-19 in HCWs is likely to be large; however, there is limited understanding of the prevalence of long COVID-19 in HCWs, or its symptoms and their clustering. This review will aim to estimate the pooled prevalence and the symptoms of long COVID-19 among HCWs infected with SARS-CoV-2 globally, and investigate differences by country, age, sex, ethnicity, vaccination status and occupation. Methods and analysis A systematic review and meta-analysis will be conducted. Medline (via Ovid), CINAHL (via EBSCO), Embase (via Ovid), PsycINFO (via EBSCO),OpenGrey(grey literature) andmedRxiv(preprint server) will be searched from the 31 December 2019 onward. All research studies and preprint articles reporting any primary data on the prevalence and/or the symptoms of long COVID-19 among adult HCWs will be included. Methodological quality will be assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data. Outcomes are anticipated to be the prevalence of long COVID-19 among HCWs around the world and trajectory of symptoms. Data synthesis will include random-effect meta-analysis for studies reporting prevalence data of long COVID-19 following SARS-CoV-2 infection among HCWs. The results will be presented with a 95% CI as an estimated effect across studies. Heterogeneity will be assessed using I² statistic. Where meta-analysis is inappropriate, a narrative synthesis of the evidence will be conducted. Ethics and dissemination Ethical approval is not needed as data will be obtained from published articles. We will publish our findings in a peer-reviewed journal and disseminate the results of our review at conferences. PROSPERO registration number CRD42022312781
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