285 research outputs found

    Spinning particle in an external linearized gravitational wave field

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    We study the interaction of a scalar and a spinning particle with a coherent linearized gravitational wave field treated as a classical spin two external field. The spin degrees of freedom of the spinning particle are described by skew-commuting variables. We derive the explicit expressions for the eigenfunctions and the Green's functions of the theory. The discussion is exact within the approximation of neglecting radiative corrections and we prove that the result is completely determined by the semiclassical contribution.Comment: 11 page

    A Re-Evaluation of the Abundance of Lutetium in the Sun

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    Lutetium is one of the few nonvolatile elements whose solar photospheric abundance departs significantly from that derived from CI chondrites. We have applied the Cowan code to compute new oscillator strengths for Luii, and have included a correction for core polarization. The results have been used in a synthesis of the solar spectrum in the vicinity of features at 3397.062 and 6221.72. We find that the majority of the absorption in the ultraviolet feature is due to NH, making it unsuitable for extracting a reliable lutetium abundance. Our best fit to the low-noise Jungfraujoch spectrum for the weak, nine-component hyperfine Luii line at λ 6221.87 yields an abundance of +0.06 on a scale where log(H) = 12.00. This value is within 0.07 dex of the meteoritic result (+0.13). (These figures reflect the note added in proof below.)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43714/1/11207_2004_Article_146254.pd

    JCV GCN in a Natalizumab-Treated MS Patient is Associated With Mutations of the VP1 Capsid Gene

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    Objective: To describe the clinical, neuroimaging, immunologic, and virologic characteristics of JC virus-associated granule cell neuronopathy (JCV GCN) in a natalizumab-treated patient with multiple sclerosis (MS) who developed immune reconstitution inflammatory syndrome (IRIS) after natalizumab withdrawal. Methods: We obtained longitudinal clinical data as well as MRI and proton magnetic resonance spectroscopy from this patient with MS. We measured JCV-specific cellular immune response in his peripheral blood by intracellular cytokine staining and sequenced a fragment of JCV VP1 capsid gene detected in his CSF. We contrast our findings with the first recently reported case. Results: This patient presented with worsening cerebellar symptoms and progressive cerebellar atrophy without new MS lesions on MRI after 63 months of natalizumab monotherapy. JCV DNA was detected in his CSF by PCR and harbored novel GCN-type mutations in the VP1 gene. He developed IRIS upon discontinuation of natalizumab and plasma exchange, which manifested itself by a worsening of clinical symptoms and contrast enhancement in the cerebellum on MRI. Treatment with corticosteroids resulted in resolution of IRIS, as demonstrated by proton magnetic resonance spectroscopy. The patient had a strong JCV-specific T-cell response in his peripheral blood and remains alive after 15 months from onset of symptoms, although with significant disability. He did not have MS relapse on glatiramer acetate. Conclusions: JCV GCN should be considered in patients on natalizumab presenting with progressive cerebellar symptoms and cerebellar atrophy, and is associated with mutations in the JCV VP1 gene. Natalizumab withdrawal may be complicated by JCV GCN IRIS, and require treatment with corticosteroids

    An Atlas of K-line Spectra for Cool Magnetic CP Stars: The Wing-Nib Anomaly (WNA)

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    We present a short atlas illustrating the unusual Ca {\sc ii} K-line profiles in upper main sequence stars with anomalous abundances. Slopes of the profiles for 10 cool, magnetic chemically peculiar (CP) stars change abruptly at the very core, forming a deep "nib." The nibs show the same or nearly the same radial velocity as the other atomic lines. The near wings are generally more shallow than in normal stars. In three magnetic CP stars, the K-lines are too weak to show this shape, though the nibs themselves are arguably present. The Ca {\sc ii} H-lines also show deep nibs, but the profiles are complicated by the nearby, strong HÏ”\epsilon absorption. The K-line structure is nearly unchanged with phase in ÎČ\beta CrB and α\alpha Cir. Calculations, including NLTE, show that other possibilities in addition to chemical stratification may yield nib-like cores.Comment: 6 pages, 2 figures, and 8 figures; accepted for publication in ApJ

    Lessons from Love-Locks: The archaeology of a contemporary assemblage

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    This document is the Accepted Manuscript version. The final, definitive version of this paper has been published in Journal of Material Culture, November 2017, published by SAGE Publishing, All rights reserved.Loss of context is a challenge, if not the bane, of the ritual archaeologist’s craft. Those who research ritual frequently encounter difficulties in the interpretation of its often tantalisingly incomplete material record. Careful analysis of material remains may afford us glimpses into past ritual activity, but our often vast chronological separation from the ritual practitioners themselves prevent us from seeing the whole picture. The archaeologist engaging with structured deposits, for instance, is often forced to study ritual assemblages post-accumulation. Many nuances of its formation, therefore, may be lost in interpretation. This paper considers what insights an archaeologist could gain into the place, people, pace, and purpose of deposition by recording an accumulation of structured deposits during its formation, rather than after. To answer this, the paper will focus on a contemporary depositional practice: the love-lock. This custom involves the inscribing of names/initials onto a padlock, its attachment to a bridge or other public structure, and the deposition of the corresponding key into the water below; a ritual often enacted by a couple as a statement of their romantic commitment. Drawing on empirical data from a three-year diachronic site-specific investigation into a love-lock bridge in Manchester, UK, the author demonstrates the value of contemporary archaeology in engaging with the often enigmatic material culture of ritual accumulations.Peer reviewe

    Reverberation Mapping Results for Five Seyfert 1 Galaxies

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    We present the results from a detailed analysis of photometric and spectrophotometric data on five Seyfert 1 galaxies observed as a part of a recent reverberation mapping program. The data were collected at several observatories over a 140-day span beginning in 2010 August and ending in 2011 January. We obtained high sampling-rate light curves for Mrk 335, Mrk 1501, 3C120, Mrk 6, and PG2130+099, from which we have measured the time lag between variations in the 5100 Angstrom continuum and the H-beta broad emission line. We then used these measurements to calculate the mass of the supermassive black hole at the center of each of these galaxies. Our new measurements substantially improve previous measurements of MBH and the size of the broad line-emitting region for four sources and add a measurement for one new object. Our new measurements are consistent with photoionization physics regulating the location of the broad line region in active galactic nuclei.Comment: 45 pages, 5 figures. Accepted for publication in ApJ. For a brief video explaining the key results of this paper, see http://www.youtube.com/user/OSUAstronom

    Reverberation Mapping of the Seyfert 1 Galaxy NGC 7469

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    A large reverberation mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hbeta 4861 and He II 4686 and a central black hole mass measurement of about 10 million solar masses, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of recovering velocity-delay maps from the data, but with the new Hbeta measurement, NGC 7469 is no longer an outlier in the relationship between the size of the Hbeta-emitting broad-line region and the AGN luminosity. It was necessary to detrend the continuum and Hbeta and He II 4686 line light curves and those from archival UV data for different time-series analysis methods to yield consistent results.Comment: 9 Pages, 7 figures, 6 tables. Accepted for publication in The Astrophysical Journa

    A Reverberation Lag for The High-Ionization Component of the Broad-Line Region in the Narrow-Line Seyfert 1 Mrk 335

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    We present the first results from a detailed analysis of photometric and spectrophotometric data on the narrow-line Seyfert 1 (NLS1) galaxy Mrk 335, collected over a 120 day span in the fall of 2010. From these data we measure the lag in the He ii λ 4686 broad emission line relative to the optical continuum to be 2.7 °Ê 0.6 days and the lag in the HÎČλ 4861 broad emission line to be 13.9 °Ê 0.9 days. Combined with the line width, the He ii lag yields a black hole mass MBH = (2. 6 °Ê 0. 8) °Þ 107M . This measurement is consistent with measurements made using the HÎČλ 4861 line, suggesting that the He ii emission originates in the same structure as HÎČ , but at a much smaller radius. This constitutes the first robust lag measurement for a high-ionization line in an NLS1 galaxy and supports a scenario in which the He ii emission originates from gas in virial motion rather than outflow

    The magnetic Bp star 36 Lyncis, I. Magnetic and photospheric properties

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    This paper reports the photospheric, magnetic and circumstellar gas characteristics of the magnetic B8p star 36 Lyncis (HD 79158). Using archival data and new polarised and unpolarised high-resolution spectra, we redetermine the basic physical properties, the rotational period and the geometry of the magnetic field, and the photospheric abundances of various elements.}{Based on magnetic and spectroscopic measurements, we infer an improved rotational period of 3.83475±0.000023.83475\pm 0.00002 d. We determine a current epoch of the longitudinal magnetic field positive extremum (HJD 2452246.033), and provide constraints on the geometry of the dipole magnetic field (i\geq 56\degr, 3210G≀Bd≀39303210 {\rm G}\leq B_{\rm d}\leq 3930 G, ÎČ\beta unconstrained). We redetermine the effective temperature and surface gravity using the optical and UV energy distributions, optical photometry and Balmer line profiles (Teff=13300±300T_{\rm eff}=13300\pm 300 K, log⁥g=3.7−4.2\log g=3.7-4.2), and based on the Hipparcos parallax we redetermine the luminosity, mass, radius and true rotational speed (L=2.54±0.16L⊙,M=4.0±0.2M⊙,R=3.4±0.7R⊙,veq=45−61.5L=2.54\pm 0.16 L_\odot, M=4.0\pm 0.2 M_\odot, R=3.4\pm 0.7 R_\odot, v_{\rm eq}=45-61.5 \kms). We measure photospheric abundances for 21 elements using optical and UV spectra, and constrain the presence of vertical stratification of these elements. We perform preliminary Doppler Imaging of the surface distribution of Fe, finding that Fe is distributed in a patchy belt near the rotational equator. Most remarkably, we confirm strong variations of the Hα\alpha line core which we interpret as due to occultations of the star by magnetically-confined circumstellar gas.Comment: Accepted by Astronomy and Astrophysic

    The Penny’s Dropped: Renegotiating the contemporary coin deposit

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    This is the Accepted Manuscript of the following article: Ceri Houlbrook, “The penny’s dropped: Renegotiating the contemporary coin deposit”, Journal of Material Culture, Vol. 20(2): 173-189, March 2015. The final published version is available at: http://journals.sagepub.com/doi/pdf/10.1177/1359183515577120#articleCitationDownloadContainer © 2015, © SAGE Publications.This article examines the status of coins as contemporary deposits in the British Isles. With a focus on both historical and contemporary sites, from the Neolithic long barrow of Wayland’s Smithy, Oxfordshire, to the plethora of wishing-wells and coin-trees distributed across the British Isles, it demonstrates the popularity of coins as ritual deposits. The author considers how they are perceived and treated by site custodians, and concludes with a case study of an archaeological excavation, the 2013 Ardmaddy Wishing-Tree Project, which recovered a large amount of contemporary coin deposits. This article does not aim to locate itself within the debates of site custodianship and accessibility, nor does it propose to address the broader dilemmas of a site’s ritual continuity or resurgence. Instead, its aim is to encourage archaeologists to consider the contemporary deposit as an integral part of the ritual narrative of a site, rather than as disposable ‘ritual litter’.Peer reviewedFinal Accepted Versio
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