1,724,165 research outputs found
The Age of the Inner Halo Globular Cluster NGC 6652
Get PDFHubble Space Telescope (V, I) photometry has been obtained for the inner halo globular cluster NGC 6652. The photometry reaches ~4 mag below the turnoff and includes a well-populated horizontal branch. This cluster is located close to the Galactic center, at RGC 2.0 kpc, with a reddening of E(V-I) = 0.15 ± 0.02, and has a metallicity of [Fe/H] -0.85. Based upon ΔV, NGC 6652 is 11.7 ± 1.6 Gyr old. Using ΔV, precise differential ages for 47 Tuc (a thick disk globular cluster), M107, and NGC 1851 (both halo clusters) were obtained. NGC 6652 appears to be the same age as 47 Tuc and NGC 1851 (within ±1.2 Gyr), while there is a slight suggestion that M107 is older than NGC 6652 by 2.3 ± 1.5 Gyr. As this is a less than 2 σ result, this issue needs to be investigated further before a definitive statement regarding the relative age of M107 and NGC 6652 may be made
S1 OPM 6652.pdf
No full textInteractive 3D PDF of Pickett Mammoth tusk (OPM 6652), digitized by Joseph E. Peterson and Ashley Boegh
Variability of the Pulsed Radio Emission from the Large Magellanic Cloud Pulsar PSR J0529-6652
Get PDFWe have studied the variability of PSR J0529–6652, a radio pulsar in the Large Magellanic Cloud (LMC), using observations conducted at 1390 MHz with the Parkes 64 m telescope. PSR J0529–6652 is detectable as a single pulse emitter, with amplitudes that classify the pulses as giant pulses. This makes PSR J0529–6652 the second known giant pulse emitter in the LMC, after PSR B0540–69. The fraction of the emitted pulses detectable from PSR J0529–6652 at this frequency is roughly two orders of magnitude greater than it is for either PSR B0540–69 or the Crab pulsar (if the latter were located in the LMC). We have measured a pulse nulling fraction of 83.3% ± 1.5% and an intrinsic modulation index of 4.07 ± 0.29 for PSR J0529–6652. The modulation index is significantly larger than values previously measured for typical radio pulsars but is comparable to values reported for members of several other neutron star classes. The large modulation index, giant pulses, and large nulling fraction suggest that this pulsar is phenomenologically more similar to these other, more variable sources, despite having spin and physical characteristics that are typical of the unrecycled radio pulsar population. The large modulation index also does not appear to be consistent with the small value predicted for this pulsar by a model of polar cap emission outlined by Gil & Sendyk. This conclusion depends to some extent on the assumption that PSR J0529–6652 is exhibiting core emission, as suggested by its simple profile morphology, narrow profile width, and previously measured profile polarization characteristics
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
New Variable Stars in NGC 6652 and Its Background Sagittarius Stream
No full textWe conducted a variable star search on the metal-rich Galactic globular cluster NGC 6652 using archival Gemini-S/Gemini Multiobject Spectrograph data. We report the discovery of nine new variable stars in the NGC 6652 field, of which we classify six as eclipsing binaries and one as an SX Phoenicis star, leaving two variables without classification. Using proper motions from Gaia DR2 and Hubble Space Telescope, albeit with some uncertainties, we find that the cluster, the field, and the background Sagittarius stream each have three of these variables. We also reassess the membership of known variables based on the Gaia proper motions, confirming the existence of one RR Lyrae star in the cluster
5-6652-01: Shear Behavior of Spliced Post-tensioned Girders With Ungrouted Tendons
No full textUS Transportation Collection2022PDFBriefBayrak, OguzhanHan, SangyoungZaborac, JarrodWebb, Zachary DChoi, JongkwonFerche, Anca CUniversity of Texas at Austin. Center for Transportation ResearchTexas. Dept. of Transportation. Research and Technology Implementation OfficeUnited States. Department of Transportation. University Transportation Centers (UTC) ProgramUniversity of Texas at Austin. Center for Transportation ResearchUnited StatesBridgesCalibrationGirdersShear propertiesTendonsAASHTO LRFDGrouted DuctNominal Shear ResistancePost-Tensioned MemberPost-TensioningSpliced Precast GirderUngrouted Duct5-6652-01The spliced girder research program conducted as part of TxDOT Project 0-6652 investigated the implications of spliced girder technology and resulted in updating the AASHTO LRFD Bridge Design Specification\u2019s (AASHTO LRFD) General Procedure for shear design, which was originally developed based on the results of small-scale panel tests. However, TxDOT Project 0-6652 evaluated large-scale post-tensioned members with grouted ducts only. Thus, the AASHTO LRFD general shear design provisions are currently based on an incomplete database of specimens and could result in potentially poorly designed spliced girders with the ungrouted ducts. Thus, large-scale testing was necessary to investigate the response of ungrouted post-tensioning systems.143
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