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While bookstores play the vital role in book distribution, little attention has been paid to concentration and conglomerate ownership in the retail book trade. In 1958, one-store book firms accounted for nearly 80 percent of book sales; by 1982 that figure had fallen to 26 percent even though single-store retailers continue to account for a majority of all bookstore outlets. Today the chains control at least 54 percent of bookstore sales. Buoyed by discriminatory discounts and publisher-subsidized advertising campaigns, the chains’ dramatic growth seems likely to continue despite the fact that they are less profitable than independent booksellers. The chains’ marketing orientation fits well with changes in the broader publishing industry, as publishers seek to rationalize operations in order to improve the bottom line. As books become just another commodity, sold through increasingly centralized and monopolized channels, access for alternative and minority voices is being for-closed.  相似文献   
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Searching online information resources using mobile devices is affected by small screens which can display only a fraction of ranked search results. In this paper we investigate whether the search effort can be reduced by means of a simple user feedback: for a screenful of search results the user is encouraged to indicate a single most relevant document. In our approach we exploit the fact that, for small display sizes and limited user actions, we can construct a user decision tree representing all possible outcomes of the user interaction with the system. Examining the trees we can compute an upper limit on relevance feedback performance. In this study we consider three standard feedback algorithms: Rocchio, Robertson/Sparck-Jones (RSJ) and a Bayesian algorithm. We evaluate them in conjunction with two strategies for presenting search results: a document ranking that attempts to maximize information gain from the user’s choices and the top-D ranked documents. Experimental results indicate that for RSJ feedback which involves an explicit feature selection policy, the greedy top-D display is more appropriate. For the other two algorithms, the exploratory display that maximizes information gain produces better results. We conducted a user study to compare the performance of the relevance feedback methods with real users and compare the results with the findings from the tree analysis. This comparison between the simulations and real user behaviour indicates that the Bayesian algorithm, coupled with the sampled display, is the most effective. Extended version of “Evaluating Relevance Feedback Algorithms for Searching on Small Displays, ” Vishwa Vinay, Ingemar J. Cox, Natasa Milic-Frayling, Ken Wood published in the proceedings of ECIR 2005, David E. Losada, Juan M. Fernández-Luna (Eds.), Springer 2005, ISBN 3-540-25295-9  相似文献   
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This article arises from a four week study of a class of 14‐15 year old students. The study explored students’ perception of themselves as writers and the effects of a variety of teaching and learning strategies on their creative writing responses. The aim of the project was to enhance the students’ creative writing, whilst ascertaining whether there were particular activities or types of writing that would lead to students perceiving more satisfactory outcomes in their writing. It answers the research question: What do I observe, and what do my students say, about the experience of different classroom based creative writing tasks?  相似文献   
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