1,721,145 research outputs found
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
Varieties over special fields
No full textIn the previous chapter we dealt with algebraic and geometric objects over arbitrary fields. In this chapter we explain additional properties of these objects when considered over special fields. We concentrate on varieties over the complex numbers and finite fields
Background on Weil descent
No full textWeil descent — or, as it is alternatively called — scalar restriction, is a well-known technique in algebraic geometry. It is applicable to all geometric objects like curves, differentials, and Picard groups, if we work over a separable field L of degree d of a ground field K. It relates t-dimensional objects over L to td-dimensional objects over K. As guideline the reader should use the theory of algebraic curves over C, which become surfaces over R. This example, detailed in Section 5.1.2, already shows that the structure of the objects after scalar restriction can be much richer: the surfaces we get from algebraic curves carry the structure of a Riemann surface and so methods from topology and Kähler manifolds can be applied to questions about curves over C.
This was the reason to suggest that Weil descent should be studied with respect to (constructive and destructive) applications for DL systems [FRE 1998]. We shall come to such applications in Sections 15.3 and 22.3.
In the next two sections we give a short sketch of the mathematical properties of Weil descent. The purpose is to provide a mathematical basis for the descent and show how to construct it. For a thorough discussion in the frame of algebraic geometry and using the language of schemes, we refer to [Die 2001
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
Complex multiplication
No full textIn this chapter we present a method for finding a curve and the group order of its Jacobian which can be seen as complementary to those in Sections 17.2 and 17.3. Instead of trying several random curves over a fixed finite field until a good one is found and determining the group order by computing the characteristic polynomial of the Frobenius endomorphism, we start with the endomorphism ring and vary the prime until one with a good group order is found. These checks can be computed relatively fast. Only the last step of actually computing the equation of the curve requires some effort, but at that time one knows already that the result is the desired one. On the other hand the curves one can construct are somewhat special as the running time depends on the discriminant of the CM-field and thus only small discriminants are possible. The approach works in general for curves of arbitrary genus but the implementation has to be done for each genus separately. We first detail it for elliptic curves as it is easier to understand there. In genus g = 2 we can efficiently compute curves with the CM method. This is in contrast to the fact that point counting over fields of large characteristic as described in Section 17.2 is still rather
inefficient and to date needs about one week to determine the order of the Jacobian of a genus two curve over the prime field with p = 5× 1024 + 8503491 [GASC 2004a].
For larger genera the constructions are possible in principle, but the difficulty is that hyperelliptic curves become very rare. We give some indications on what is possible and which difficulties have to be dealt with. For genus g = 3 we give examples of curves with additional automorphisms
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
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