1,721,149 research outputs found

    Bounds on the Constrained Capacity for the Diffusive Poisson Molecular Channel with Memory

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    This letter focuses on the analysis of a diffusion-based molecular communication (MC) system where the received signal is approximated as a Poisson random variable. Concentration shift keying (CSK) is used as the modulation technique for encoding information in the system. In particular, this work aims to study the performance of the MC system in terms of reliable information exchange for the channel with finite-state memory, which introduces intersymbol interference (ISI). The main objective is the derivation of analytical expressions for the upper and the lower bound of the constrained channel capacity for a range of values of the modulated symbols, i.e., for a number of different sets of amplitude levels of CSK modulation, and for various levels of ISI. In addition, the numerical evaluation of the derived expressions is presented. Results allow discussing the relationship between ISI level and achievable channel capacity. Moreover, numerical outcomes highlight how the estimation of the bounds is not affected by the presence of ISI in the case of binary CSK modulation, as the bounds remain quite tight

    An Iterative Approach for Estimating Information Exchange in Cell-to-cell Molecular Communication

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    The characterization of biological systems in terms of communication performance is currently limited. In this paper, an iterative method is presented for evaluating mutual information in molecular communication systems composed of genetically engineered cells, based on an indirect non-parametric estimation of probability density functions. Results are presented based on the application of this method to proof-of-concept in-silico data generated via stochastic simulation

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

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    “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

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    We 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

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    We 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

    Author Index

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