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Urn models Markov chains and random walks in cosmological topologically massive gravity at the critical point
No full textFragmented perspective of self-organized criticality and disorder in log gravity
No full textAbstract We use a statistical model to discuss nonequilibrium fragmentation phenomena taking place in the stochastic dynamics of the log sector in log gravity. From the canonical Gibbs model, a combinatorial analysis reveals an important aspect of the n-particle evolution previously shown to generate a collection of random partitions according to the Ewens distribution realized in a disconnected double Hurwitz number in genus zero. By treating each possible partition as a member of an ensemble of fragmentations, and ensemble averaging over all partitions with the Hurwitz number as a special case of the Gibbs distribution, a resulting distribution of cluster sizes appears to fall as a power of the size of the cluster. Dynamical systems that exhibit a distribution of sizes giving rise to a scale-invariant power-law behavior at a critical point possess an important property called self-organized criticality. As a corollary, the log sector of log gravity is a self-organized critical system at the critical point μl = 1. A similarity between self-organized critical systems, spin glass models and the dynamics of the log sector which exhibits aging behavior reminiscent of glassy systems is pointed out by means of the Pòlya distribution, also known to classify various models of (randomly fragmented) disordered systems, and by presenting the cluster distribution in the log sector of log gravity as a distinguished member of this probability distribution. We bring arguments from a probabilistic perspective to discuss the disorder in log gravity, largely anticipated through the conjectured AdS3/LCFT2 correspondence
Shannon information entropy, soliton clusters and Bose-Einstein condensation in log gravity
Get PDFWe give a probabilistic interpretation of the configurational partition
function of the logarithmic sector of critical cosmological topologically
massive gravity, in which the Hurwitz numbers considered in our previous works
assume the role of probabilities in a distribution on cycles of permutations.
In particular, it is shown that the permutations are distributed according to
the Ewens sampling formula which plays a major role in the theory of partition
structures and their applications to diffusive processes of fragmentation, and
in random trees. This new probabilistic result together with the previously
established evidence of solitons in the theory provide new insights on the
instability originally observed in the theory. We argue that the unstable
propagation of a seed soliton at single particle level induces the generation
of fragments of defect soliton clusters with rooted tree configuration at
multiparticle level, providing a disordered landscape. The Shannon information
entropy of the probability distribution is then introduced as a measure of the
evolution of the unstable soliton clusters generated. Finally, based on
Feynman's path integral formalism on permutation symmetry in the
-transition of liquid helium, we argue that the existence of
permutation cycles in the configurational log partition function indicates the
presence of Bose-Einstein condensates in log gravity.Comment: Minor changes to match published versio
Moduli space of logarithmic states in critical massive gravities
Get PDFWe take new algebraic and geometric perspectives on the combinatorial results
recently obtained on the partition functions of critical massive gravities
conjectured to be dual to Logarithmic CFTs throught the AdS/LCFT
correspondence. We show that the partition functions of logarithmic states can
be expressed in terms of Schur polynomials. Subsequently, we show that the
moduli space of the logarithmic states is the symmetric product . As the quotient of an affine space by the symmetric
group, this orbifold space is shown to be described by Hilbert series that have
palindromic numerators. The palindromic properties of the Hilbert series
indicate that the orbifolds are Calabi-Yau, and allow for a new interpretation
of the logarithmic state spaces in critical massive gravities as Calabi-Yau
singular spaces.Comment: Minor changes to match published versio
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
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
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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