1,721,176 research outputs found
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
Analytical method development for measurement of unregulated organic contaminants in aqueous samples using liquid chromatography - tandem mass spectrometry
No full textOrganic wastewater contaminants (OWCs) such as pharmaceuticals, hormones, and perfluorinated compounds (PFCs) are of growing environmental and public health concern. These OWCs were found in U.S. drinking water supplies according to nationwide studies by the U.S. Geological Survey. Many OWCs are not, however, regulated or routinely monitored in drinking water. The objective of this dissertation was to develop and optimize analytical methods for trace analysis of unregulated organic contaminants in drinking water sources. Furthermore, household water treatment-processes were studied to measure the efficacy of removal of these unregulated organic contaminants from drinking water samples. Two liquid chromatography-ion trap mass spectrometry systems (LC-IT-MS/MS) were compared for rapid, reliable and sensitive detection of the most abundant PFCs, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). An ultra performance LC-linear IT-MS/MS achieved the lowest detection limits measured, 0.03pg and 0.24pg for PFOA and PFOS respectively, which were approximately two orders of magnitude more sensitive than an LC-IT-MS/MS. With the increased sensitivity, the direct analysis of PFOA/S without solid phase extraction pre-concentration steps was also demonstrated. In addition, MS methods using Full Scan, Single Ion Monitoring, and MS/MS were compared and optimized for a sensitive analysis of PFCs. A novel rapid method was created by switching polarity for the simultaneous analysis of twenty unregulated compounds, including pharmaceuticals. Sensitive method detection limits were achieved in the range of sub ng/L to hundreds ng/L for all target compounds. An optimized analytical method was applied to quantify low ng/L levels of these target compounds in field water samples from regions throughout New Jersey. Eight target compounds were measured below 1µg/L and two target compounds (i.e. metformin and estradiol) were measured slightly above 1µg/L in the field water samples. Finally, granular activated carbon (GAC) and ion resin (Brita™) filtration, ozonation, and microwave heating were tested for efficacy at removing 20 target compounds in drinking water samples. The GAC/ion resin mechanism with adsorption properties demonstrated greater removal of the target compounds than the other two mechanisms. Even this water treatment-process only partially removed these target compounds with its mean removal of ≤ 66%.Ph.D.Includes abstractVitaIncludes bibliographical referencesby Min K. Yoo
자원 활용을 고려한 맵리듀스 기반 멀티웨이 조인 처리
No full textWith a growing demand of hidden insights from the large scale of data, multi-way join operations become the key of many OLAP-style data analytic tasks for not only relational data analysis, but also various scientific applications. To process OLAP-style data analytic tasks with cost-efficiency, shared-nothing distributed system, such as MapReduce, gets its popularity in both academic field and enterprises. However, due to various lacks in support of MapReduce such as processing data from multiple sources and data skew handling, join operation is inefficient operation in MapReduce. Specifically, generation of query execution plan in MapReduce does not consider the dominantly utilized resources that affect the performance of a query processing significantly. Our work is based on a counter observations from traditional wisdoms of query processing in MapReduce: reducing the number of MapReduce job does not guarantee the performance benefit, and growing intermediate data does not always triggers the performance degradation.
In this work, we propose efficient resource-aware multi-way join processing method by taking not only algorithmic approach, but also systemic approach. As an algorithmic approach, we propose in-memory streaming hash join method with careful consideration of memory constraint in a computing machine and a balanced workload of each join task. As a systemic approach, we propose a generation of efficient multi-way join query execution plan. In experimental results, our method improves the performance of multi-way join query processing, especially the latest version of Apache Hive[5], and AQUA[11]. In addition, our method shows better performance even if the aggregated intermediate data is larger than other method by exploiting major resources very efficiently. ⓒ 2015 DGISTⅠ. INTRODUCTION --
Ⅱ. BACKGROUND --
2.1 MapReduce --
2.2 SQL-on-Hadoop --
Ⅲ. JOIN PROCESSING USING MAPREDUCE --
3.1 Basic join algorithms in MapReduce --
3.2 Replicated join --
3.3 1-Bucket-Theta --
Ⅳ. RESOURCE-AWARE MULTI-WAY JOIN PROCESSING --
4.1 Problem description --
4.2 Cost model of operator pipeline in MapReduce --
4.3 In-memory streaming hash join --
4.4 Finding multi-way join group --
Ⅴ. EXPERIMENTS --
Ⅵ. RELATED WORK --
Ⅶ. CONCLUSIONS --
Ⅷ. REFERENCEShared-nothing 구조 기반의 분산 및 병렬 데이터 처리 시스템인 맵리듀스는 데이터베이스 분야에서 부터 기초과학 및 응용과학까지 매우 광범위한 분야에서 대규모 데이터에 대한 분석을 위해 사용되고 있다. 하지만 맵리듀스는 매우 단순 한 종류의 질의 처리를 위해 만들어졌기 때문에, 대규모 데이터 분석에 사용되는 매우 복잡한 형태의 질의는 잘 처리하지 못하는 단점이 있다. 특히 데이터 분석 질의에서 매우 빈번하게 사용되는 조인 연산 처리에서 기존의 RDBMS와 비교해 볼 때 매우 비효율적으로 처리하는 Data-flow를 가지고 있다. 이러한 단점에도 불구하고, 처리해야 하는 데이터의 크기가 폭발적으로 증가함에 따라, 기존의 RDBMS 기반의 scale-up 시스템의 한계점이 분명해진 이 시점에서, 맵리듀스를 이용한 다양한 형태의 질의처리 기술, 특히 조인에 대한 효율적인 처리 방법이 매우 필요하다. 여러 가지 종류의 조인 연산 중 멀티웨이 조인 연산은 데이터로부터 의미 있는 결과를 도출하기 위해 사용되는 복잡한 질의에 매우 빈번하게 사용되며, 질의를 효율적으로 표현할 수 있게 해준다. 따라서 맵리듀스 기반의 환경에서
효율적인 멀티웨이 조인 연산의 처리 방법은 활용가치가 매우 높은 기술이라 할 수 있다.
본 논문에서는 맵리듀스를 활용한 효율적인 멀티웨이 조인 처리 방법에 대해 다룬다. 특히, 조인 연산에서 매우 빈번하게 발생하는 메모리 오버플로우 (memory overflow) 문제와 멀티웨이 조인 연산의 느린 처리 속도를 개선하기 위해 알고리즘과 시스템 두 가지 관점에서 효율적인 방법을 제안한다. 첫째로, 알고리즘 적인 관점에서 본 논문은 인-메모리 기반의 스트리밍 조인 방법을 제안한다. 특히, 조인 연산 처리 중 발생하기 쉬운 메모리 오버플로우 문제를 해결하기 위한 데이터 파티셔닝 (data partitioning) 방법을 다룬다. 그리고 복잡질의를 처리하기 위한 일련의 맵리듀스 작업간의 데이터 이동을 최대한 줄이기 위해 최적화된 조인 순서를 생성하는 방법을 다룬다. 또한 시스템적인 관점에서 맵리듀스 연산 처리시의 시스템 자원간의 성능차이를 비용모델로 도출하고 이를 활용해 가장 빠른 자원을 최대한 활용할 수 있도록 하는 효율적인 복잡 질의 실행 계획 생성 방법을 제안한다. 여러 가지 TPC-H 질의와 생성 데이터를 사용한 실험에서 우리가 제안한 멀티웨이 조인 처리 방법이 가장 최신의 Apache Hive[5]와 AQUA [11]에서 제안한 질의 처리 계획을 사용하였을 때 보다 대부분의 경우에서 좋은 성능을 보이고 있으며, 주요 자원에 대한 효율적 사용으로 인해 합계된 중간데이터의 크기가 늘어나더라도 좋은 성능을 보인다. ⓒ 2015 DGISTMasterdCollectio
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
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