1,721,101 research outputs found
Unveiling the disk-jet system in the massive (proto)star IRAS 20126+4104
No full textWe present the results of line and continuum observations towards the source IRAS 20126+4104, performed at 1.3 mm and 3.5 mm with the Plateau de Bure interferometer, from 350 mu m to 2 mm with the James Clerk Maxwell telescope, and at 10 and 20 mu m with the United Kingdom infrared telescope. The results fully confirm the findings of Cesaroni et al. (\cite{cftwo}), namely that IRAS 20126+4104 is a very young stellar object embedded in a dense, hot core and lying at the centre of a rotating disk. The bipolar jet imaged by Cesaroni et al. (\cite{cftwo}) in the 2.122 mu m H_2 line is seen also in the SiO(2-1) transition, which allows to study the velocity field in the jet. A simple model is developed to obtain the inclination angle of the jet (and hence of the disk axis), which turns out to be almost perpendicular to the line of sight. By studying the diameter of the disk in different transitions and the corresponding line widths and peak velocities, one can demonstrate that the disk is Keplerian and collapsing, and thus compute the mass of the central object and the accretion luminosity. We show that if all the mass inducing the Keplerian rotation is concentrated in a single star, then this cannot be a ZAMS star, but more likely a massive protostar which derives its luminosity from accretion
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
POL-2: A Polarimeter for SCUBA-2
No full textSCUBA-2 is a bolometer array camera for use at the James Clerk Maxwell Telescope (JCMT) and is currently under development in the UK, Canada, and the USA. This new instrument will work in two wavelength bands, 850 and 450 microns, and is currently scheduled to start operation in 2006. Here we present current options for a polarimeter, POL-2, that is being built for SCUBA-2. The polarimeter will have an achromatic continuously rotating half-wave plate in order to modulate the signal at a rate faster than atmospheric transparency fluctuations. Such a modulation should improve significantly the reliability and accuracy of sub-mm polarimetric measurements. The signal will be analyzed by a wire-grid polarizer. For calibration, a removable polarizer will also be available. The components, in the order that the radiation will encounter them, are the calibration polarizer, the rotating wave plate, and the polarizer. The components will be mounted in a box fixed permanently in front of the entrance window of the main cryostat of SCUBA-2. All components will be mounted so that they can be taken in and out of the beam remotely, making it very easy and fast to start doing polarimetry at the telescope. Software will be provided to control all the basic functions of the polarimeter. A data reduction pipeline capable of producing near publication quality results will be provided for both on-line and off-line reduction of polarimetric data. This polarimeter will be the most sensitive instrument for the detection of polarized radiation in the submillimetre regime. This will be possible by taking advantage of the extra sensitivity, imaging speed, and improved image fidelity of the new SCUBA-2 camera
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