1,721,034 research outputs found
A COMPARATIVE ANALYSIS OF SOME STATISTICAL PROPERTIES OF THE HIPPARCOS CATALOGUE B. Bucciarelli
No full textDue to the unprecedented astrometric quality of the Hipparcos Catalogue, presently available astrometric catalogues cannot be used to independently assess its statistical properties. However, a relatively inexpensive way to address systematic errors at the sub-mas level is to intercompare the FAST and NDAC results before their merging. Moreover, by means of an empirical covariance analysis it is possible to study the presence of residual signals in the Hipparcos sphere solution. This papers presents some results of these investigations. Key words: astrometry; reference catalogues; statistics. 1. SYSTEMATIC ERRORS ANALYSIS 1.1. Catalogue-to-Catalogue Reduction Prior to this analysis, the FAST and NDAC catalogues have been put onto the same reference system (H30, i.e. approximately FK5). Then, the method of infinitely overlapping circles (IOC) has been used to analyse the high angular frequency systematics, following the prescriptions of a similar study performed on the FAST/NDAC 30-mon..
A comparison between two strategies of data reduction for the Hipparcos project
No full textTwo different strategies for reducing HIPPARCOS data are directly compared and their respective impact on the final precision of the HIPPARCOS Catalog is evaluated. These strategies are the FAST (Fundamental Astronomy by Space Techniques) Consortium's Baseline and GLOBUS procedures. The Baseline is already operating on satellite data; GLOBUS was invented as an alternative and more rigorous approach to the adjustment of the HIPPARCOS astrometric network. At present, FAST is supporting a possible introduction of GLOBUS in its data reduction chain. In order to make a true comparison, the two methods were applied to the same 1-year simulation of HIPPARCOS mission data. The comparison shows that the overall precision of the solution given by the GLOBUS approach is ∼ 20% better than the Baseline one
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
Information and communication:two special issues for Geomatics
Full text linkInformation Systems may be considered as a part of universal media. The survey and mapping disciplines, particularly Photogrammetry, Remote sensing and GIS, can give very important contribution to many human activities, but they can also be negatively used to support, in very sophisticated ways, the escalation of armies, wars and destruction: in many cases of warfare, information is vital, regardless for the aim.. So some form of control is mandatory on the part of right-minded scientists and technicians: Human Sciences may be of great help for a better interpretation of information
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
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