STORRE
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The STORRE digital repository system captures, stores, indexes, preserves, and distributes digital research material.2019-08-25T12:16:15ZNESTs: Disconnections between theory, research and practice
http://hdl.handle.net/1893/30025
Title: NESTs: Disconnections between theory, research and practice
Author(s): Copland, Fiona; Mann, Steve; Garton, Sue
Abstract: First paragraph: Native speakerism is an ideology positing that native speakers provide the best models of the target language and for this reason make the best teachers of the language (e.g., Pennycook, 1994; Holliday, 2005). The ideology has been robustly criticised by scholars on a number of grounds, for example, the fallacy of the native speaker (e.g., Piller, 2001), race (e.g., Kubota & Lin, 2009); prejudice and discrimination (Houghton & Rivers, 2013) and linguistic imperialism (e.g., Phillipson, 1992; 2016). Native speaker English teachers (NESTs) are considered, by default, one of the conduits through which English language and its teaching methodology have been exported globally. It is not surprising, therefore, that discussions are generally unenthusiastic about NESTs and their influence (e.g., Bunce, 2016; Machida & Walsh, 2015; Wong et al. 2016), which has resulted in the term often exuding negative associations.Query Filtering with Low-Dimensional Local Embeddings
http://hdl.handle.net/1893/30024
Title: Query Filtering with Low-Dimensional Local Embeddings
Author(s): Chávez, Edgar; Connor, Richard; Vadicamo, Lucia
Abstract: The concept of local pivoting is to partition a metric space so that each element in the space is associated with precisely one of a fixed set of reference objects or pivots. The idea is that each object of the data set is associated with the reference object that is best suited to filter that particular object if it is not relevant to a query, maximising the probability of excluding it from a search. The notion does not in itself lead to a scalable search mechanism, but instead gives a good chance of exclusion based on a tiny memory footprint and a fast calculation. It is therefore most useful in contexts where main memory is at a premium, or in conjunction with another, scalable, mechanism. In this paper we apply similar reasoning to metric spaces which possess the four-point property, which notably include Euclidean, Cosine, Triangular, Jensen-Shannon, and Quadratic Form. In this case, each element of the space can be associated with two reference objects, and a four-point lower-bound property is used instead of the simple triangle inequality. The probability of exclusion is strictly greater than with simple local pivoting; the space required per object and the calculation are again tiny in relative terms. We show that the resulting mechanism can be very effective. A consequence of using the four-point property is that, for m reference points, there arèarè m 2 ´ pivot pairs to choose from, giving a very good chance of a good selection being available from a small number of distance calculations. Finding the best pair has a quadratic cost with the number of references ; however, we provide experimental evidence that good heuristics exist. Finally, we show how the resulting mechanism can be integrated with a more scalable technique to provide a very significant performance improvement, for a very small overhead in build-time and memory cost. Keywords: metric search · extreme pivoting · supermetric space · four-point property · pivot based index 2 Chávez et al.SPLX-Perm: A Novel Permutation-Based Representation for Approximate Metric Search
http://hdl.handle.net/1893/30023
Title: SPLX-Perm: A Novel Permutation-Based Representation for Approximate Metric Search
Author(s): Vadicamo, Lucia; Connor, Richard; Falchi, Fabrizio; Gennaro, Claudio; Rabitti, Fausto
Abstract: Many approaches for approximate metric search rely on a permutation-based representation of the original data objects. The main advantage of transforming metric objects into permutations is that the latter can be efficiently indexed and searched using data structures such as inverted-files and prefix trees. Typically, the permutation is obtained by ordering the identifiers of a set of pivots according to their distances to the object to be represented. In this paper, we present a novel approach to transform metric objects into permutations. It uses the object-pivot distances in combination with a metric transformation, called n-Simplex projection. The resulting permutation-based representation , named SPLX-Perm, is suitable only for the large class of metric space satisfying the n-point property. We tested the proposed approach on two benchmarks for similarity search. Our preliminary results are encouraging and open new perspectives for further investigations on the use of the n-Simplex projection for supporting permutation-based indexing.Compensation of Trial-to-Trial Latency Jitter Reveals the Parietal Retrieval Success Effect to be Both Variable and Thresholded in Older Adults
http://hdl.handle.net/1893/30022
Title: Compensation of Trial-to-Trial Latency Jitter Reveals the Parietal Retrieval Success Effect to be Both Variable and Thresholded in Older Adults
Author(s): Murray, Jamie G; Ouyang, Guang; Donaldson, David I
Abstract: Although the neural mechanism supporting episodic recollection has been well characterized in younger adults, exactly how recollection is supported in older adults remains unclear. The electrophysiological correlate of recollection-the parietal retrieval success effect-for example, has been shown to be sensitive to both the amount of information recollected and the accuracy of remembered information in younger adults. To date, there is mixed evidence that parietal effect also scales with the amount of information remembered in older adults whilst there is little evidence that the same mechanism is sensitive to the accuracy of recollected information. Here, we address one potential concern when investigating Event Related Potentials (ERPs) among older adults-namely, the greater potential for single-trial latency variability to smear and reduces the amplitudes of averaged ERPs. We apply a well-established algorithm for correcting single-trial latency variability, Residual Iteration Decomposition Analysis (RIDE), to investigate whether the parietal retrieval success effect among older adults is sensitive to retrieval accuracy. Our results reveal that similar to younger adults, older adult parietal retrieval success effects scale with the accuracy of recollected information-i.e., is greater in magnitude when recollected information is of high accuracy, reduced in magnitude when accuracy is low, and entirely absent when guessing. The results help clarify the functional significance of the neural mechanism supporting recollection in older adults whilst also highlighting the potential issues with interpreting average ERPs in older adult populations.2019-07-23T00:00:00Z