2,073 research outputs found

    A Catalogue of Galaxies Having Radial Velocities: Volume 15: Part 7

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    A tabulation of galaxies which have radial velocities is presented. The parameters of each galaxy are: (1) an abbreviation for the catalog designation, (2) RA(1950), (3) Dec. (1950), (4) new galactic longitude, (5) new galactic latitude, (6) morphological type, (7) magnitude, (8) observed radial velocity in kilometers per second (9) radial velocity corrected for solar motion, and (10) estimated error in radial velocity in kilometers per second

    Coherent network analysis for continuous gravitational wave signals in a pulsar timing array: Pulsar phases as extrinsic parameters

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    Supermassive black hole binaries are one of the primary targets for gravitational wave searches using pulsar timing arrays. Gravitational wave signals from such systems are well represented by parametrized models, allowing the standard Generalized Likelihood Ratio Test (GLRT) to be used for their detection and estimation. However, there is a dichotomy in how the GLRT can be implemented for pulsar timing arrays: there are two possible ways in which one can split the set of signal parameters for semi-analytical and numerical extremization. The straightforward extension of the method used for continuous signals in ground-based gravitational wave searches, where the so-called pulsar phase parameters are maximized numerically, was addressed in an earlier paper (Wang et al. 2014). In this paper, we report the first study of the performance of the second approach where the pulsar phases are maximized semi-analytically. This approach is scalable since the number of parameters left over for numerical optimization does not depend on the size of the pulsar timing array. Our results show that, for the same array size (9 pulsars), the new method performs somewhat worse in parameter estimation, but not in detection, than the previous method where the pulsar phases were maximized numerically. The origin of the performance discrepancy is likely to be in the ill-posedness that is intrinsic to any network analysis method. However, scalability of the new method allows the ill-posedness to be mitigated by simply adding more pulsars to the array. This is shown explicitly by taking a larger array of pulsars.Comment: 30 pages, 11 figures, revised version, published in Ap

    A coherent method for the detection and estimation of continuous gravitational wave signals using a pulsar timing array

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    The use of a high precision pulsar timing array is a promising approach to detecting gravitational waves in the very low frequency regime (10610910^{-6} -10^{-9} Hz) that is complementary to the ground-based efforts (e.g., LIGO, Virgo) at high frequencies (10103\sim 10 -10^3 Hz) and space-based ones (e.g., LISA) at low frequencies (10410110^{-4} -10^{-1} Hz). One of the target sources for pulsar timing arrays are individual supermassive black hole binaries that are expected to form in galactic mergers. In this paper, a likelihood based method for detection and estimation is presented for a monochromatic continuous gravitational wave signal emitted by such a source. The so-called pulsar terms in the signal that arise due to the breakdown of the long-wavelength approximation are explicitly taken into account in this method. In addition, the method accounts for equality and inequality constraints involved in the semi-analytical maximization of the likelihood over a subset of the parameters. The remaining parameters are maximized over numerically using Particle Swarm Optimization. Thus, the method presented here solves the monochromatic continuous wave detection and estimation problem without invoking some of the approximations that have been used in earlier studies.Comment: 33 pages, 10 figures, submitted to Ap

    Diagnosis and management of pneumonia in the emergency department.

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    Pneumonia is a condition that is often treated by emergency physicians. This article reviews the diagnosis and management of pneumonia in the emergency department and highlights dilemmas in diagnostic testing, use of blood and sputum cultures, hospital admission decisions, infection control, quality measures for pneumonia care, and empiric antimicrobial therapy

    Sensing Aesthetic Resonance in the Light of Hyperbolic Explication: An Exploration of Gulzar’s “Leaves in Autumn” and “The River”

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    This research paper intends to explore the aesthetic resonance of Gulzar’s “Leaves in Autumn” and “The River” in the light of hyperbole. Gulzar, India’s most respected director and screenwriter, has composed poems on nature and its relative subjects. The theme of the selected poems is mounted on nature. Gulzar has elevated the theme and style of the poems using imagination. “The River” portrays the river and the aesthetic changes that take place in him. In “Leaves in Autumn”, the poet has rendered human qualities to the tree, the primary character of the poem. Discovering the aesthetic beauty and the imaginative portrayal of nature are the principal aims of “Sensing Aesthetic Resonance in the Light of Hyperbolic Explication: An Exploration of Gulzar’s “Leaves in Autumn” and “The River””. This research paper has used aesthetic appreciation of beauty with reference to the tenets of hyperbole as its methodology to elicit the pulchritude of nature in the selected poems

    Facilitating Better Teamwork: Analyzing the Challenges and Strategies of Classroom-Based Collaboration

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    To help students develop teamwork skills, teachers should be aware of the strategies students already employ to assert authority and manage conflict. Researchers studying engineering students have identified two such approaches: transfer-of-knowledge sequences, in which students emulate teacher and pupil roles; and collaborative sequences, in which students use circular talk to reach consensus. As demonstrated in this article, these strategies are also used by students in professional communication courses. The second half of this article provides specific suggestions for designing team assignments, interacting effectively with student teams, and developing evaluations that value the process of teamwork

    Practicing Professional Communication Principles by Creating Public Service Announcements

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    A PRIMARY GOAL of most introductory business and technical communication courses is to introduce students to the idea that the professional communication most of them will engage in is different from the writing they do for academic purposes. This overall idea covers several principles concerning professional writing. First, in an academic essay, a student may tell all he or she knows about a topic to an expert reader (the instructor); in professional writing situations, however, writers are most likely sharing only a small part of the information they know with nonexpert readers. Second, when writing in professional situations, writers must actively envision audiences different from themselves, audiences that will have different concerns and purposes than the writers do. Finally, the audience, purpose, and medium of a professional communication situation drive the choices a writer will make. If students are to understand these principles, discussing them in class is insufficient; students must also practice them
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