1,720,960 research outputs found
Bicriteria data compression
Get PDFIn this paper we address the problem of trading optimally, and in a principled way, the compressed size/decompression time of LZ77 parsings by introducing what we call the Bicriteria LZ77-Parsing problem.
The goal is to determine an LZ77 parsing which minimizes the space occupancy in bits of the compressed file, provided that the decompression time is bounded by T. Symmetrically, we can exchange the role of the two resources and thus ask for minimizing the decompression time provided that the compressed space is bounded by a fixed amount given in advance.
We address this goal in three stages: (i) we introduce the novel Bicriteria LZ77-Parsing problem which formalizes in a principled way what data-compressors have traditionally approached by means of heuristics; (ii) we solve this problem efficiently, up to a negligible additive constant, in O(nlog2 n) time and optimal O(n) words of working space, by proving and deploying some specific structural properties of a weighted graph derived from the possible LZ77-parsings of the input file; (iii) we execute a preliminary set of experiments which show that our novel compressor is very competitive to all the highly engineered competitors (such as Snappy, lzma, bzip2), hence offering a win-win situation in theory&practice
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
Bicriteria Data Compression: Efficient and Usable
Get PDFLempel-Ziv's LZ77 algorithm is the de facto choice for compressing massive datasets (see e.g., Snappy in BigTable, Lz4 in Cassandra) because its algorithmic structure is flexible enough to guarantee very fast decompression speed at reasonable compressed-space occupancy. Recent theoretical results have shown how to design a bit-optimal LZ77-compressor which minimizes the compress size and how to deploy it in order to design a bicriteria data compressor, namely an LZ77-compressor which trades compressed-space occupancy versus its decompression time in a smoothed and principled way. Preliminary experiments were promising but raised many algorithmic and engineering questions which have to be addressed in order to turn these algorithmic results into an effective and practical tool. In this paper we address these issues by first designing a novel bit-optimal LZ77-compressor which is simple, cache-aware and asymptotically optimal. We benchmark our approach by investigating several algorithmic and implementation issues over many dataset types and sizes, and against an ample class of classic (LZ-based, PPM-based and BWT-based) as well as engineered compressors (Snappy, Lz4, and Lzma2). We conclude noticing how our novel bicriteria LZ77-compressor improves the state-of-the-art of fast (de)compressors Snappy and Lz4. © 2014 Springer-Verlag Berlin Heidelberg
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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