1,721,018 research outputs found
Optical Monitoring of bright Blazars with Automatic Telescopes
No full textWell sampled light curves of BL Lac objects are very useful to
understand the physical processes responsible for the highly variable
emission from this class of AGN. The best way to perform the necessary
high number of observations is the use of automatic small aperture
telescopes. We present some results of the Perugia-Roma monitoring
program concerning the recent active phase of BL Lac and the Intra-Day
Variability of S5 0716+714
YY ERI revisited
No full textThe RV Cass spectrograph at ESO has been used to observe the W UMa star YY Eri, in order to obtain the spectroscopic mass ratio of its components. A new technique has been successfully applied for the measure of radial velocities from intermediate dispersion spectra. The fit of the radial velocities has been done using a Roche lobe model of stellar surfaces which takes into account the distortion of the radial velocity curves due to tidal effects. As a by-product of the procedure a new photometric solution of YY Eri has been obtained through a simultaneous treatment of B and V bands data
The TACOR educational telescope and the Italian RemoteLab Project-Learning tools for the International Year of Astronomy 2009
No full text
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
Spectral slope variability of BL Lacertae objects in the optical band
No full textLight curves of eight BL Lac objects in the BVRI bands have been analyzed. All of the objects tend to be bluer when brighter. However, spectral slope changes differ quantitatively from those of a sample of QSOs analyzed in a previous paper by Trevese & Vagnetti and appear to be consistent with a different nature of the optical continuum. A simple model representing the variability of a synchrotron component can explain the spectral changes. Constraints on a possible thermal accretion disk component contributing to the optical luminosity 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
- …
