1,721,162 research outputs found
Near-infrared photometry and spectroscopy of NGC 6539 and UKS 1: two intermediate metallicity bulge globular clusters
No full textUsing the `son of ISAAC' (Infrared Spectrometer And Array Camera) imager at the European Southern Observatory New Technology Telescope and the near-infrared spectrographs on Keck II, we have obtained J, K images and echelle spectra covering the range 1.5-1.8mum for the intermediate metallicity bulge globular clusters NGC 6539 and UKS 1. We find [Fe/H]=-0.76 and -0.78, respectively, and an average alpha-enhancement of ~+0.44 and ~+0.31 dex, consistent with previous measurements of metal-rich bulge clusters, and favouring the scenario of rapid chemical enrichment. We also measure very low 12C/13C ~ 4.5 +/- 1 isotopic ratios in both clusters, suggesting that extra-mixing mechanisms due to cool bottom processing are at work during evolution along the red giant branch. Finally, we measure accurate radial velocities of =+31 +/- 4 and =+57 +/- 6 km s-1 and velocity dispersions of ~8 and ~11 km s-1 for NGC 6539 and UKS 1, respectivel
High-Resolution Infrared Spectroscopy of the Old Open Cluster NGC 6791
No full textWe report abundance analysis for six M giant members of the old open cluster NGC 6791, based on infrared spectroscopy (1.5-1.8 mum) at R=25,000, using the NIRSPEC spectrograph at the Keck II telescope. We find the iron abundance =+0.35+/-0.02, confirming the supersolar metallicity of this cluster as derived from optical medium-high resolution spectroscopy. We also measure C, O, and other alpha-element abundances, finding a roughly solar value of [alpha/Fe] and =-0.35. Our approach constrains [O/Fe] especially well, on the basis of the measurement of a number of OH lines near 1.6 mum we find [O/Fe]=-0.07+/-0.03. The solar value of [alpha/Fe] is in contrast to the composition of similar stars in the Galactic bulge. We also find a low value of 12C/13C~10, confirming the presence of extramixing processes during the red giant phase of evolution, up to supersolar metallicities
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
The Evolution of Oxygen and Magnesium in the Bulge and Disk of the Milky Way
No full textWe show that the Galactic bulge and disk share a similar, strong, decline in [O/Mg] ratio with [Mg/H]. The similarity of the [O/Mg] trend in these markedly different populations suggests that the strong decline is due to a metallicity-dependent modulation of the stellar yields from massive stars by mass loss from winds, related to the Wolf-Rayet phenomenon, as proposed by McWilliam & Rich in 2004. We have modified existing models for the chemical evolution of the Galactic bulge and the solar neighborhood with the inclusion of metallicity-dependent oxygen yields from theoretical predictions for massive stars that include mass loss by stellar winds. Our results significantly improve the agreement between predicted and observed [O/Mg] ratios in the bulge and disk above solar metallicity; however, a small zero-point normalization problem remains to be resolved. The zero-point shift indicates that either the semi-empirical yields of François et al. obtained in 2004 need adjustment, or that the bulge initial mass function (IMF) is not quite as flat as found by Ballero et al. in 2007. Our result removes a previous inconsistency between the interpretation of [O/Fe] and [Mg/Fe] ratios in the bulge, and confirms the conclusion that the bulge formed more rapidly than the disk, based on the overabundances of elements produced by massive stars. We also provide an explanation for the long-standing difference between [α/Fe] and [O/Fe] trends among disk stars more metal rich than th
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