7,985 research outputs found

    Extending Romanovski polynomials in quantum mechanics

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    Some extensions of the (third-class) Romanovski polynomials (also called Romanovski/pseudo-Jacobi polynomials), which appear in bound-state wavefunctions of rationally-extended Scarf II and Rosen-Morse I potentials, are considered. For the former potentials, the generalized polynomials satisfy a finite orthogonality relation, while for the latter an infinite set of relations among polynomials with degree-dependent parameters is obtained. Both types of relations are counterparts of those known for conventional polynomials. In the absence of any direct information on the zeros of the Romanovski polynomials present in denominators, the regularity of the constructed potentials is checked by taking advantage of the disconjugacy properties of second-order differential equations of Schr\"odinger type. It is also shown that on going from Scarf I to Scarf II or from Rosen-Morse II to Rosen-Morse I potentials, the variety of rational extensions is narrowed down from types I, II, and III to type III only.Comment: 25 pages, no figure, small changes, 3 additional references, published versio

    Image Subtraction Reduction of Open Clusters M35 & NGC 2158 In The K2 Campaign-0 Super-Stamp

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    Observations were made of the open clusters M35 and NGC 2158 during the initial K2 campaign (C0). Reducing these data to high-precision photometric time-series is challenging due to the wide point spread function (PSF) and the blending of stellar light in such dense regions. We developed an image-subtraction-based K2 reduction pipeline that is applicable to both crowded and sparse stellar fields. We applied our pipeline to the data-rich C0 K2 super-stamp, containing the two open clusters, as well as to the neighboring postage stamps. In this paper, we present our image subtraction reduction pipeline and demonstrate that this technique achieves ultra-high photometric precision for sources in the C0 super-stamp. We extract the raw light curves of 3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for systematic effects. We compare our photometric results with the prior reductions published in the literature. For detrended, TFA-corrected sources in the 12--12.25 Kp\rm K_{p} magnitude range, we achieve a best 6.5 hour window running rms of 35 ppm falling to 100 ppm for fainter stars in the 14--14.25 Kp \rm K_{p} magnitude range. For stars with Kp>14\rm K_{p}> 14, our detrended and 6.5 hour binned light curves achieve the highest photometric precision. Moreover, all our TFA-corrected sources have higher precision on all time scales investigated. This work represents the first published image subtraction analysis of a K2 super-stamp. This method will be particularly useful for analyzing the Galactic bulge observations carried out during K2 campaign 9. The raw light curves and the final results of our detrending processes are publicly available at \url{http://k2.hatsurveys.org/archive/}.Comment: Accepted for publication in PASP. 14 pages, 5 figures, 2 tables. Light curves available from http://k2.hatsurveys.org/archive

    High-Energy Neutrinos from Photomeson Processes in Blazars

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    An important radiation field for photomeson neutrino production in blazars is shown to be the radiation field external to the jet. Assuming that protons are accelerated with the same power as electrons and injected with a -2 number spectrum, we predict that km^2 neutrino telescopes will detect about 1-to-several neutrinos per year from flat spectrum radio quasars (FSRQs) such as 3C 279. The escaping high-energy neutron and photon beams transport inner jet energy far from the black-hole engine, and could power synchrotron X-ray jets and FR II hot spots and lobes.Comment: revised paper (minor revisions), accepted for publication in PR

    Anti-Hispanic prejudice drives opposition to immigration in the U.S.

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    Last June, the U.S. Senate passed a comprehensive immigration bill that would give legal status to 11 million undocumented migrants, but this bill has remained stalled in the House of Representatives, reflecting the anti-immigration sentiments of many Americans. New research from Todd K. Hartman, Benjamin J. Newman, and C. Scott Bell investigates why so many are against immigration reform, and the role played by racial prejudice against Hispanics. Using surveys designed to detect anti-Hispanic prejudice, they find that white Americans react very differently to law-violating behaviors whether they are committed by Hispanic immigrants or not, suggesting a significant and persistent bias against them

    A near-NHEK/CFT correspondence

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    We consider excitations around the recently introduced near-NHEK metric describing the near-horizon geometry of the near-extremal four-dimensional Kerr black hole. This geometry has a U(1)_L x U(1)_R isometry group which can be enhanced to a pair of commuting Virasoro algebras. We present boundary conditions for which the conserved charges of the corresponding asymptotic symmetries are well defined and non-vanishing and find the central charges c_L=12J/hbar and c_R=0 where J is the angular momentum of the black hole. Applying the Cardy formula reproduces the Bekenstein-Hawking entropy of the black hole. This suggests that the near-extremal Kerr black hole is holographically dual to a non-chiral two-dimensional conformal field theory.Comment: 11 pages, v2: references updated, adde

    A note on Kerr/CFT and free fields

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    The near-horizon geometry of the extremal four-dimensional Kerr black hole and certain generalizations thereof has an SL(2,R) x U(1) isometry group. Excitations around this geometry can be controlled by imposing appropriate boundary conditions. For certain boundary conditions, the U(1) isometry is enhanced to a Virasoro algebra. Here, we propose a free-field construction of this Virasoro algebra.Comment: 10 pages, v2: comments and references adde

    On the CFT duals for near-extremal black holes

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    We consider Kerr-Newman-AdS-dS black holes near extremality and work out the near-horizon geometry of these near-extremal black holes. We identify the exact U(1)_L x U(1)_R isometries of the near-horizon geometry and provide boundary conditions enhancing them to a pair of commuting Virasoro algebras. The conserved charges of the corresponding asymptotic symmetries are found to be well defined and non-vanishing and to yield central charges c_L\neq0 and c_R=0. The Cardy formula subsequently reproduces the Bekenstein-Hawking entropy of the black hole. This suggests that the near-extremal Kerr-Newman-AdS-dS black hole is holographically dual to a non-chiral two-dimensional conformal field theory.Comment: 11 page

    An R- and I-Band Photometric Variability Survey of the Cygnus OB2 Association

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    We present a catalog of photometrically variable stars discovered within two 21'.3 X 21'.3 fields centered on the Cygnus OB2 association. There have hitherto been no deep optical variability studies of Cyg OB2 despite it being replete with early-type massive stars, perhaps due to the high and variable extinction (up to A_V ~ 20) that permeates much of the region. Here we provide results of the first variability study with this combination of spatial coverage (~ 0.5 deg) and photometric depth (R ~ 21 mag). We find 121 stars to be variable in both R- and I-band, 116 of them newly discovered. Of the 121 variables, we identify 27 eclipsing binaries (EBs) and eclipsing binary candidates, 20 potential Herbig Ae/Be stars, and 52 pulsating variables. Confirming both the status and the cluster membership of the Herbig Ae/Be stars would address the uncertainty regarding the age and star formation history of Cyg OB2. We match our catalog to known variables and binaries in the region, 2MASS near-IR (NIR) data, and Chandra X-ray observations to find counterparts to new variables in other wavelengths.Comment: 34 pages, 12 figures, submitted to Ap

    Kettle test efficacy in predicting cognitive and functional outcomes in geriatric rehabilitation

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    Background/aim: Limited research has been available to support the use of the Kettle Test in a subacute rehabilitation setting with patients diagnosed with a variety of medical conditions. The Kettle Test is an occupation based performance measure designed to detect cognitive processes and function. The aim of this research was to measure the correlation between three cognitive tests, the Mini-Mental State Examination (MMSE), Cognitive Functional Independence Measure (Cognitive FIM) and the Kettle Test. Secondly, to assess the efficacy of these tests in predicting functional outcomes via the motor subscale of the Functional Independence Measure (mFIM). Methods: A prospective single-centre cohort study in a subacute rehabilitation setting of 97 patients. Results: Correlation coefficients between the tests were statistically significant and moderately strong, with values ranging from 0.593 to _0.589. Significant positive correlations were seen between admission MMSE, Cognitive FIM and the mFIM and significant negative correlations between Kettle Test scores and the mFIM. The Kettle Test score had a stronger relationship with mFIM (r = _0.40; P \u3c 0.01) compared to the Cognitive FIM (r = 0.33; P \u3c 0.01) and MMSE (r = 0.26; P \u3c 0.05). The Kettle Test variance is significantly associated with the MMSE and Cognitive FIM at admission and discharge measures. Modelling identified that age and gender significantly contribute to this relationship. When adjusted for age and gender the MMSE and Cognitive FIM both explained the 47% of the variance at discharge. Conclusion: There were statistically significant inter-test correlations between the MMSE, Cognitive FIM and Kettle Test. The Kettle Test had the strongest relationship to patient functional outcomes
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