1,721,161 research outputs found
Crackling Noise : Statistical Physics of Avalanche Phenomena
No full textThe response of materials and the functioning of devices is often associated with noise. In this book, Stefano Zapperi concentrates on a particular type of noise, known as crackling noise, which is characterized by an intermittent series of broadly distributed pulses. While representing a nuisance in many practical applications, crackling noise can also tell us something useful about the microscopic processes ruling the materials behavior. Each crackle in the noise series usually corresponds to a localized impulsive event, an avalanche, occurring inside the material. A distinct statistical feature of crackling noise, and of the underlying avalanche behavior, is the presence of scaling, observed as power-law distributed noise pulses, long-range correlation, and scale free spectra. These are the hallmarks of critical phenomena and phase transitions.
This work summarizes the current understanding of crackling noise, reviewing research undertaken in the past 30 years, from the early and influential ideas on self-organized criticality in sandpile models, to more modern studies on disordered systems. Crackling Noise covers the main theoretical models used to investigate avalanche phenomena, describes the statistical tools needed to analyze crackling noise, and provides a detailed discussion of a set of relevant examples of crackling noise in materials science. These include acoustic emission in fracture, strain bursts in amorphous and crystal plasticity, granular avalanches, magnetic noise in ferromagnets and superconductors, and fluid flow in porous media. The book concludes by considering the wider application of these models in the natural sciences
T. Pievani and F. Sanguettoli, The evolution of exaptation, and how exaptation survived Dennett's criticism
No full textPhase transitions in cell migration
Full text linkCaterina La Porta and Stefano Zapperi discuss how a suitable identification of the control and order parameters can shed light on the nature of phase transitions in cell migration.
Phase transitions from a static to a moving phase are observed in a variety of physical systems and are thought to play a key role in cellular assemblies such as healthy and cancerous tissue. Caterina La Porta and Stefano Zapperi discuss how a suitable identification of the control and order parameters can shed light on the nature of phase transitions in cell migration
Comment on “first-order transition in the breakdown of disordered media”
No full textA Comment on the Letter by Stefano Zapperi, et al., Phys. Rev. Lett. 78, 1408 (1997). The authors of the Letter offer a Reply. © 1999 The American Physical Society
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
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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