1,720,971 research outputs found
The effect of a superoutburst on the white dwarf and disk of VW Hydri as observed with FUSE
No full textWe have used Far Ultraviolet Spectroscopic Explorer (FUSE) to obtain a series of 13 observations of the nearby dwarf nova VW Hyi that cover the period from the end of a superoutburst through the following normal outburst of the system. Here, we present the quiescent spectra taken after each outburst event. The spectra obtained during quiescence contain at least three components. The dominant component over most of the FUSE wavelength range is the white dwarf (WD), which cools following the superoutburst. The amount of cooling is dependent on the WD models utilized. For log g of 8.0, the temperature drops from 24,000 K just after the outburst to 20,000 K just before the normal outburst. For this model, and for a distance of 65 pc, the radius of the WD is approximately 8 x 10(8) cm and nu sin (i) is similar to 420 km s(-1). The fact that the derived radius is smaller than expected for a WD with log g = 8 suggests a higher gravity WD or that VW Hyi is somewhat further than its canonical distance of 65 pc. Either is possible given the current uncertainty (+/- 20 pc) in the distance to VW Hyi. Earlier suggestions that the WD photosphere show evidence of CNO processed material are confirmed, but our analysis also highlights the fact that significant issues remain in terms of analyzing the spectra of WDs in such unusual physical situations. The second component is relatively featureless and shows substantial modulation on the orbital (and just after outburst, the superhump) period. The second component is most likely associated with the hot spot where material from the secondary encounters the disk, rather than emission from the boundary layer region between the inner disk and WD. This second component fades about 10 days after the superoutburst. There is also a third component, clearly visible in terms of broad emission lines of C III lambda 977, N III lambda 991, and a combination of Ly beta and O VI..1032, 1038, which appears to be accompanied by a flat continuum. The strength of the emission lines, which are almost surely associated with the accretion disk, appears relatively constant for the duration of the observations
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Unveiling unresolved stellar components from photometry: The case of TWA 23 and the importance of pre-whitening
Get PDFSpace-born missions designed to search for exo-planets are providing us with high-precision photometric time series very well suited to measure the rotation period of solar- and lower-mass stars. Considering the large number of stars monitored during the mission life, the possibility to inspect each periodogram is out of question and, therefore, each method to search for rotation periods applied either individually or in combination is designed to automatically select the best rotation period estimate. In the case of unresolved binary stars it is possible to measure the rotation period of both components, when these are both variable and have comparable magnitude. On the other hand, the detection of two different rotation periods from the same photometric timeseries can represents a tool to unveil the binary nature of the star. In this paper, we present the case of the star TWA 23, a member of the young TWA association, as just one example of numerous cases. These may occur when the star is an unresolved binary and the variability of the secondary component is present in the time series. However, the frequency of the primary and dominant power peak in the periodogram, originating from the primary component, needs to be pre-whitened to allow the frequency of the secondary component to be detected. Considering the possible presence of undiscovered close binaries in the input catalogs of various ongoing or future missions aimed at exoplanet search, it becomes advisable to follow routinely this filtering approach to prevent to miss relevant information on the true binary nature of stars
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
