1,720,991 research outputs found
Mobile geometric graphs:Detection, coverage and percolation
Full text linkWe consider the following dynamic Boolean model introduced by van den Berg et al. (Stoch. Process. Appl. 69:247–257, 1997). At time 0, let the nodes of the graph be a Poisson point process in Rd with constant intensity and let each node move independently according to Brownian motion. At any time t, we put an edge between every pair of nodes whose distance is at most r. We study three fundamental problems in this model: detection (the time until a target point—fixed or moving—is within distance r of some node of the graph); coverage (the time until all points inside a finite box are detected by the graph); and percolation (the time until a given node belongs to the infinite connected component of the graph). We obtain precise asymptotics for these quantities by combining ideas from stochastic geometry, coupling and multi-scale analysis
Mixing and hitting times for Markov chains - 3
No full textMixing and hitting times are fundamental parameters of a Markov chain. In this mini-course I will discuss connections between them for reversible Markov chains.Non UBCUnreviewedAuthor affiliation: University of CambridgePostdoctora
Total variation cutoff in a tree
No full textNon UBCUnreviewedAuthor affiliation: University of CambridgePostdoctora
Uniformity of late points of random walk in for d>2
No full textNon UBCUnreviewedAuthor affiliation: University of CambridgePostdoctora
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
Logarithmic corrections to scaling in the four-dimensional uniform spanning tree
Full text linkWe compute the precise logarithmic corrections to mean-field scaling for
various quantities describing the uniform spanning tree of the four-dimensional
hypercubic lattice . We are particularly interested in the
distribution of the past of the origin, that is, the finite piece of the tree
that is separated from infinity by the origin. We prove that the probability
that the past contains a path of length is of order ,
that the probability that the past contains at least vertices is of order
, and that the probability that the past reaches the
boundary of the box is of order . An
important part of our proof is to prove concentration estimates for the
capacity of the four-dimensional loop-erased random walk which may be of
independent interest.
Our results imply that the Abelian sandpile model also exhibits non-trivial
polylogarithmic corrections to mean-field scaling in four dimensions, although
it remains open to compute the precise order of these corrections.Comment: 80 pages. V2: Minor revisions. Accepted version, to appear in CM
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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