1,720,964 research outputs found
Timely and cost-efficient data exploration through adaptive tuning
No full textModern applications accumulate data at an exponentially increasing rate and traditional database systems struggle to keep up.
Decision support systems used in industry, rely heavily on data analysis, and require real-time responses irrespective of data size.
To offer real-time support, traditional databases require long preprocessing steps, such as data loading and offline tuning. Loading transforms raw data into a format that reduces data access cost.
Through tuning, database systems build access paths (e.g., indexes) to improve query performance by avoiding or reducing unnecessary data access. The decision on what access paths to build depends on the expected workload, thus, the database system assumes knowledge of
future queries. However, decision support systems and data exploration applications have shifting requirements. As a consequence, an offline tuner with no a priori knowledge of the full workload is unable to decide on the optimal set of access paths.
Furthermore, access path size increases along with input data, thus, building precise access paths over the entire dataset limits the scalability of databases systems.
Apart from long database pre-processing, offering efficient data access despite increasing data volume becomes harder due to hardware architectural constraints such as memory size. To achieve low query latency, modern database systems store data in main memory. However, there is a physical limit on main memory size in a server. Thereby, applications must trade memory space for query efficiency.
To provide high performance efficiency, irrespective of dataset growth and query workload, a database system needs to
(i) shift the decision of tuning from off-line to query-time,
(ii) enable the query engine to exploit application properties in choosing fast access paths, and
(iii) reduce the size of access paths to limit storage cost.
In this thesis, we present techniques for query processing that are adaptive to workload, application requirements, and available storage resources. Specifically, to address dynamic workloads, we turn access path
creation into a continuous process which fully adapts to incoming queries. We assign all decisions on data access and access path materialization to the database optimizer at query time, and enable
access path materialization to take place as a by-product of query execution, thereby, removing requirements for long offline tuning processing steps.
Furthermore, we take advantage of application characteristics (precision requirements, resource availability) and we design a system which can adaptively trade precision and resources for
performance. By combining precise and approximate access paths, the database system reduces query response time and minimizes resource utilization. Approximate access paths (e.g., sketches) require less
space in comparison to their precise counterparts, and offer constant access time.
By improving data processing performance while reducing storage requirements through
(i) adaptive access path materialization and
(ii) using approximate and space-efficient access paths when appropriate, our work minimizes data access cost and provides real-time responses for data exploration applications irrespective of data growth.DIA
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
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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