1,165 research outputs found

    Weak-lensing calibration of a stellar mass-based mass proxy for redMaPPer and Voronoi Tessellation clusters in SDSS Stripe 82

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    We present the first weak lensing calibration of μ⋆\mu_{\star}, a new galaxy cluster mass proxy corresponding to the total stellar mass of red and blue members, in two cluster samples selected from the SDSS Stripe 82 data: 230 redMaPPer clusters at redshift 0.1≤z<0.330.1\leq z<0.33 and 136 Voronoi Tessellation (VT) clusters at 0.1≤z<0.60.1 \leq z < 0.6. We use the CS82 shear catalog and stack the clusters in μ⋆\mu_{\star} bins to measure a mass-observable power law relation. For redMaPPer clusters we obtain M0=(1.77±0.36)×1014h−1M⊙M_0 = (1.77 \pm 0.36) \times 10^{14}h^{-1} M_{\odot}, α=1.74±0.62\alpha = 1.74 \pm 0.62. For VT clusters, we find M0=(4.31±0.89)×1014h−1M⊙M_0 = (4.31 \pm 0.89) \times 10^{14}h^{-1} M_{\odot}, α=0.59±0.54\alpha = 0.59 \pm 0.54 and M0=(3.67±0.56)×1014h−1M⊙M_0 = (3.67 \pm 0.56) \times 10^{14}h^{-1} M_{\odot}, α=0.68±0.49\alpha = 0.68 \pm 0.49 for a low and a high redshift bin, respectively. Our results are consistent, internally and with the literature, indicating that our method can be applied to any cluster finding algorithm. In particular, we recommend that μ⋆\mu_{\star} be used as the mass proxy for VT clusters. Catalogs including μ⋆\mu_{\star} measurements will enable its use in studies of galaxy evolution in clusters and cluster cosmology.Comment: Updated to be consistent with the published versio

    A Case Study of Low-Mass Star Formation

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    This article synthesizes observational data from an extensive program aimed toward a comprehensive understanding of star formation in a low-mass star-forming molecular cloud. New observations and published data spanning from the centimeter wave band to the near infrared reveal the high and low density molecular gas, dust, and pre-main sequence stars in L1551.Comment: 24 pages, 21 figures, ApJS accepte

    Optical and Infrared Analysis of Type II SN 2006BC

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    We present nebular phase optical imaging and spectroscopy and near/mid-IR imaging of the Type II SN 2006bc. Observations reveal the central wavelength of the symmetric Hα\alpha line profile to be red-shifted with respect to the host galaxy Hα\alpha emission by day 325. Such an phenomenon has been argued to result from an asymmetric explosion in the iron-peak elements resulting in a larger mass of 56^{56}Ni and higher excitation of hydrogen on the far side of the SN explosion. We also observe a gradual blue-shifting of this Hα\alpha peak which is indicative of dust formation in the ejecta. Although showing a normal peak brightness, V ∼\sim -17.2, for a core-collapse SN, 2006bc fades by ∼\sim6 mag during the first 400 days suggesting either a relatively low 56^{56}Ni yield, an increase in extinction due to new dust, or both. A short duration flattening of the light curve is observed from day 416 to day 541 suggesting an optical light echo. Based on the narrow time window of this echo, we discuss implications on the location and geometry of the reflecting ISM. With our radiative transfer models, we find an upper limit of 2 x 10−3^{-3} M⊙_{\odot} of dust around SN 2006bc. In the event that all of this dust were formed during the SN explosion, this quantity of dust is still several orders of magnitude lower than that needed to explain the large quantities of dust observed in the early universe.Comment: 6 pages, 10 figures, accepted for publication in Ap

    How to find an attractive solution to the liar paradox

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    The general thesis of this paper is that metasemantic theories can play a central role in determining the correct solution to the liar paradox. I argue for the thesis by providing a specific example. I show how Lewis’s reference-magnetic metasemantic theory may decide between two of the most influential solutions to the liar paradox: Kripke’s minimal fixed point theory of truth and Gupta and Belnap’s revision theory of truth. In particular, I suggest that Lewis’s metasemantic theory favours Kripke’s solution to the paradox over Gupta and Belnap’s. I then sketch how other standard criteria for assessing solutions to the liar paradox, such as whether a solution faces a so-called revenge paradox, fit into this picture. While the discussion of the specific example is itself important, the underlying lesson is that we have an unused strategy for resolving one of the hardest problems in philosophy

    Tuberculosis Microepidemics among Dispersed Migrants, Birmingham, UK, 2004-2013

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    MIRU-VNTR typing was supported by the Public Health England National TB Strain Typing Project. M.M. is funded by the UK Clinical Research Collaboration Modernising Medical Microbiology Consortium. C.B. is funded by the Heart of Birmingham Primary Care Trust and Public Health England

    Anatomy of a post-starburst minor merger: a multi-wavelength WFC3 study of NGC 4150

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    (Abridged) We present a spatially-resolved near-UV/optical study of NGC 4150, using the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. Previous studies of this early-type galaxy (ETG) indicate that it has a large reservoir of molecular gas, exhibits a kinematically decoupled core (likely indication of recent merging) and strong, central H_B absorption (indicative of young stars). The core of NGC 4150 shows ubiquitous near-UV emission and remarkable dusty substructure. Our analysis shows this galaxy to lie in the near-UV green valley, and its pixel-by-pixel photometry exhibits a narrow range of near-UV/optical colours that are similar to those of nearby E+A (post-starburst) galaxies. We parametrise the properties of the recent star formation (age, mass fraction, metallicity and internal dust content) in the NGC 4150 pixels by comparing the observed near-UV/optical photometry to stellar models. The typical age of the recent star formation (RSF) is around 0.9 Gyrs, consistent with the similarity of the near-UV colours to post-starburst systems, while the morphological structure of the young component supports the proposed merger scenario. The RSF metallicity, representative of the metallicity of the gas fuelling star formation, is around 0.3 - 0.5 Zsun. Assuming that this galaxy is a merger and that the gas is sourced mainly from the infalling companion, these metallicities plausibly indicate the gas-phase metallicity (GPM) of the accreted satellite. Comparison to the local mass-GPM relation suggests (crudely) that the mass of the accreted system is around 3x10^8 Msun, making NGC 4150 a 1:20 minor merger. A summation of the pixel RSF mass fractions indicates that the RSF contributes about 2-3 percent of the stellar mass. This work reaffirms our hypothesis that minor mergers play a significant role in the evolution of ETGs at late epochs.Comment: 28 pages, 2 tables, accepted for publication in Ap

    Probable delirium is a presenting symptom of COVID-19 in frail, older adults: a cohort study of 322 hospitalised and 535 community-based older adults

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    BACKGROUND: Frailty, increased vulnerability to physiological stressors, is associated with adverse outcomes. COVID-19 exhibits a more severe disease course in older, comorbid adults. Awareness of atypical presentations is critical to facilitate early identification. OBJECTIVE: To assess how frailty affects presenting COVID-19 symptoms in older adults. DESIGN: Observational cohort study of hospitalised older patients and self-report data for community-based older adults. SETTINGS: Admissions to St Thomas’ Hospital, London with laboratory-confirmed COVID-19. Community-based data for older adults using the COVID Symptom Study mobile application. SUBJECTS: Hospital cohort: patients aged 65 and over (n = 322); unscheduled hospital admission between 1 March 2020 and 5 May 2020; COVID-19 confirmed by RT-PCR of nasopharyngeal swab. Community-based cohort: participants aged 65 and over enrolled in the COVID Symptom Study (n = 535); reported test-positive for COVID-19 from 24 March (application launch) to 8 May 2020. METHODS: Multivariable logistic regression analysis performed on age-matched samples from hospital and community-based cohorts to ascertain association of frailty with symptoms of confirmed COVID-19. RESULTS: Hospital cohort: significantly higher prevalence of probable delirium in the frail sample, with no difference in fever or cough. Community-based cohort: significantly higher prevalence of possible delirium in frailer, older adults and fatigue and shortness of breath. CONCLUSIONS: This is the first study demonstrating higher prevalence of probable delirium as a COVID-19 symptom in older adults with frailty compared to other older adults. This emphasises need for systematic frailty assessment and screening for delirium in acutely ill older patients in hospital and community settings. Clinicians should suspect COVID-19 in frail adults with delirium

    An Examination of Celtic Craft and the Creative Consciousness as a Contribution to Marketing Creativity

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    Examination of the Celtic craft sector identifies a creative form of marketing which has its foundations in imagination, intuition and innovation, rather than the linear prescriptions of formal marketing frameworks and language which still dominate contemporary marketing management texts. The creative marketing competencies identified in the sector are also grounded within a wider creative marketing paradigm where experimental forms of marketing are encouraged, postmodern ideals are embraced and artistic philosophy and practice encouraged. The controlled Saxon influenced Marketing Establishment is challenged by the freer, more creative fringe of Celtic marketing as the avant garde

    A Study of the Quasi-elastic (e,e'p) Reaction on 12^{12}C, 56^{56}Fe and 97^{97}Au

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    We report the results from a systematic study of the quasi-elastic (e,e'p) reaction on 12^{12}C, 56^{56}Fe and 197^{197}Au performed at Jefferson Lab. We have measured nuclear transparency and extracted spectral functions (corrected for radiation) over a Q2^2 range of 0.64 - 3.25 (GeV/c)2^2 for all three nuclei. In addition we have extracted separated longitudinal and transverse spectral functions at Q2^2 of 0.64 and 1.8 (GeV/c)2^2 for these three nuclei (except for 197^{197}Au at the higher Q2^2). The spectral functions are compared to a number of theoretical calculations. The measured spectral functions differ in detail but not in overall shape from most of the theoretical models. In all three targets the measured spectral functions show considerable excess transverse strength at Q2^2 = 0.64 (GeV/c)2^2, which is much reduced at 1.8 (GeV/c)2^2.Comment: For JLab E91013 Collaboration, 19 pages, 20 figures, 3 table
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