Document retrieval on repetitive string collections     

Travis Gagie  Aleksi Hartikainen  Kalle Karhu  Juha Kärkkäinen  Gonzalo Navarro  Simon J. Puglisi  Jouni Sirén 《Information Retrieval》2017,20(3):253-291

Most of the fastest-growing string collections today are repetitive, that is, most of the constituent documents are similar to many others. As these collections keep growing, a key approach to handling them is to exploit their repetitiveness, which can reduce their space usage by orders of magnitude. We study the problem of indexing repetitive string collections in order to perform efficient document retrieval operations on them. Document retrieval problems are routinely solved by search engines on large natural language collections, but the techniques are less developed on generic string collections. The case of repetitive string collections is even less understood, and there are very few existing solutions. We develop two novel ideas, interleaved LCPs and precomputed document lists, that yield highly compressed indexes solving the problem of document listing (find all the documents where a string appears), top-k document retrieval (find the k documents where a string appears most often), and document counting (count the number of documents where a string appears). We also show that a classical data structure supporting the latter query becomes highly compressible on repetitive data. Finally, we show how the tools we developed can be combined to solve ranked conjunctive and disjunctive multi-term queries under the simple \({\textsf{tf}}{\textsf{-}}{\textsf{idf}}\) model of relevance. We thoroughly evaluate the resulting techniques in various real-life repetitiveness scenarios, and recommend the best choices for each case.  相似文献   

Open access megajournals: The publisher perspective (Part 1: Motivations)          下载免费PDF全文

Simon Wakeling  Valérie Spezi  Jenny Fry  Claire Creaser  Stephen Pinfield  Peter Willett 《Learned Publishing》2017,30(4):301-311

This paper is the first of two Learned Publishing articles in which we report the results of a series of interviews with senior publishers and editors exploring open access megajournals (OAMJs). Megajournals (of which PLoS One is the best known example) represent a relatively new approach to scholarly communication and can be characterized as large, broad‐scope, open access journals that take an innovative approach to peer review, basing acceptance decisions solely on the technical or scientific soundness of the article. This model is often said to support the broader goals of the open science movement. Based on in‐depth interviews with 31 publishers and editors representing 16 different organizations (10 of which publish a megajournal), this paper reports how the term ‘megajournal’ is understood and publishers’ rationale and motivations for launching (or not launching) an OAMJ. We find that while there is general agreement on the common characteristics of megajournals, there is not yet a consensus on their relative importance. We also find seven motivating factors that were said to drive the launch of an OAMJ and link each of these factors to potential societal and business benefits. These results suggest that the often polarized debate surrounding OAMJs is a consequence of the extent to which observers perceive publishers to be motivated by these societal or business benefits.  相似文献   

Regression Models with Errors in the Predictor Variable     

Simon J. Day 《Teaching Statistics》1989,11(2):50-51

In this article Simon Day describes a computer simulation exploring one of the fundamental assumptions of regression analysis which causes students difficulties.  相似文献   

ENGLISH JOKES     

Simon 《今日中学生》2008,(36)

(A)Ned:Why do you always wear two watches?Ted:I need to see how slow the other one is.(B)Passenger1:Excuse me,does this train stop at New Town?Passenger2:Yes,just watch me and get off one station beforeme.(C)Diner:Waiter,your finger is in my soup.Waiter:That's all right.It's so used to(惯常)the heat,I hardlynotice it.(D)Customer:I'd like to try on(试穿)that dress in the window(橱窗).Salesgirl:Sorry,madam,but you'll have to use the dressingroom(试衣间).(E)  相似文献   

Measuring the quality of e‐learning     

David B. Hay  Caroline Kehoe  Marc E. Miquel  Stylianos Hatzipanagos  Ian M. Kinchin  Steve F. Keevil  Simon Lygo‐Baker 《British journal of educational technology : journal of the Council for Educational Technology》2008,39(6):1037-1056

This paper shows how concept mapping can be used to measure the quality of e‐learning. Six volunteers (all of them 3rd‐year medical students) took part in a programme of e‐learning designed to teach the principles of magnetic resonance imaging (MRI). Their understanding of MRI was measured before and after the course by the use of concept mapping. The quality of change in individuals' maps was assessed using criteria developed to distinguish between meaningful and rote‐learning outcomes. Student maps were also scored for evidence of conceptual richness and understanding. Finally, each map was compared directly with the content of the electronic teaching material. The results show that many of the student misconceptions were put right in the course of their learning but that many of the key concepts introduced in the teaching were ignored (or sometimes learnt by rote) by the students. This was because the teaching material locked these new ideas in structures and terminology that precluded meaning‐making among non‐experts. Our data suggest that students' prior knowledge is a key determinant of meaningful learning. We suggest that this must be acknowledged if the design and use of electronic teaching material is also to be meaningful. Ultimately, measures of student learning are the only authentic indicators of the quality of teaching through technology.  相似文献   

Romantic Partner Selection and Socialization During Early Adolescence     

Valerie A. Simon  Julie Wargo Aikins  Mitchell J. Prinstein 《Child development》2008,79(6):1676-1692

This prospective study examined romantic partner selection and socialization among a sample of 78 young adolescents (6th–8th graders). Independent assessments of adolescent and romantic partner adjustment were collected before and after relationships initiated via peer nomination and self‐report. Prior to their relationship, adolescents and partners were significantly alike on popularity, physical attraction, and depressive symptoms. Controlling for initial similarity, partners’ popularity, depressive symptoms, relational aggression, and relational victimization significantly predicted changes in adolescents’ functioning in these areas over time. However, the magnitude and direction of change varied according to adolescents’ and partners’ prerelationship functioning. In general, adolescents who dated high‐functioning partners changed more than those who dated low‐functioning partners, and partner characteristics predicted greater change among low‐ versus high‐functioning adolescents. Results were consistent even when controlling for best friend characteristics. The current findings are among the first to demonstrate unique contributions of romantic partner characteristics to adolescents’ psychosocial functioning.  相似文献   

The Development of Chemical Language Usage by “Non-traditional” Students: the Interlanguage Analogy     

Rees  Simon  Kind  Vanessa  Newton  Douglas 《Research in Science Education》2021,51(2):419-438

Research in Science Education - Students commonly find specialist scientific language problematic. This study investigated developments in chemical language usage by six non-traditional students...  相似文献   

Richard Yeo,Science in the Public Sphere: Natural Knowledge in British Culture 1800–1860     

Schaffer  Simon 《Metascience》2003,12(1):133-137

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National and global competition in higher education   总被引：4，自引：0，他引：4  

Simon Marginson 《The Australian Educational Researcher》2004,31(2):1-28

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Computer-assisted foreign language learning: Effects of text,context, and gender on listening comprehension and motivation     

Solveig Jakobsdóttir  Simon Hooper 《Educational technology research and development : ETR & D》1995,43(4):43-59

A computer-based foreign language lesson was developed to study the effects of text, context, and gender on listening comprehension and motivation. A total of 109 fifth grade students responded to spoken commands, with text and a story absent or present. Presenting spoken language with text appeared to assist the development of listening skills. When text was present, students made fewer errors on the subsequent comprehension test and gave higher relevance and confidence motivation ratings than when text was absent. Girls demonstrated higher achievement than did boys and rated the lesson higher, indicating that girls tend to like different kinds of software than do boys. An interaction between context and gender regarding achievement was significant: Girls, but not boys, made fewer errors after a story-embedded lesson.  相似文献