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Variations of the Albanese Morphism
No full textWe estimate the number of moduli of an n-dimensional variety X through the variation of its Albanese morphism. Refining upon our methods, we work out the classical Castelnuovo bound concerning the number m of moduli of irregular surfaces with birational Albanese map. We interpret our variation by means of higher Abel-Jacobi mappings theory and under the only hypothesis that X has a generically finite morphism to an Abelian variety A, we can bound from below the geometrical genus pg(X) in terms of the dimensions of A and X. Using the same framework, we characterize the hyperelliptic locus in Mg as the only close subvariety H inside the moduli space of curves with dim H ≥ 2g - 1 and torsion Abel-Jacobi image of the Ceresa cycle at its generic point
A new curve algebraically but not rationally uniformized by radicals
Full text linkWe give a new example of a curve C algebraically, but not rationally, uniformized by radicals. This means that C has no map onto P1 with solvable Galois group, while there exists a curve C′ that maps onto C and has a finite morphism to P1 with solvable Galois group. We construct such a curve C of genus 9 in the second symmetric product of a general curve of genus 2. It is also an example of a genus 9 curve that does not satisfy condition S(4,2,9) of Abramovich and Harris
Parametrization of rational maps on a variety of general type, and the finiteness theorem
No full textIn a previous paper we provided some update in the treatment of
the finiteness theorem for rational maps of finite degree from a fixed variety to
varieties of general type. In the present paper we present another improvement,
introducing the natural parametrization of maps by means of the space of linear
projections in a suitable projective space, and this leads to some new insight
into the geometry of the finiteness theorem
On the finiteness theorem for rational maps on a variety of general type
No full textThe dominant rational maps of finite degree from a fixed variety
to varieties of general type, up to birational isomorphisms, form a finite set. This has been known as the Iitaka-Severi conjecture, and is nowdays an established result, in virtue of some recent advances in the theory of pluricanonical maps. We study the question of finding some effective estimate for the finite number of maps, and to this aim we provide some update and refinement of the classical treatment of the subject
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
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