1,721,236 research outputs found
Instanton bundles on the Segre threefold with Picard number three
Full text linkWe study instanton bundles E on P1×P1×P1. We construct two different monads which are the analog of the monads for instanton bundles on P3 and on the flag threefold F(0, 1, 2). We characterize the Gieseker semistable cases and we prove the existence of μ-stable instanton bundles generically trivial on the lines for any possible C2(E). We also study the locus of jumping lines
H-instanton bundles on three-dimensional polarized projective varieties
Full text linkWe propose a notion of instanton bundle (called H-instanton bundle) on any projective variety of dimension three polarized by a very ample divisor H, that naturally generalizes the ones on P3 and on the flag threefold F(0,1,2). We briefly discuss the cases of Veronese and Fano threefolds. Then we deal with H-instanton bundles E on three-dimensional rational normal scrolls S(a0,a1,a2). We give a monadic description of H-instanton bundles and we prove the existence of μ-stable H-instanton bundles on S(a0,a1,a2) for any admissible charge k=c2(E)H. Then we deal in more detail with S(a,a,b) and S(a0,a1,a2) with a0+a1>a2 and even degree. Finally we describe a nice component of the moduli space of μ-stable bundles whose points represent H-instantons
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
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