Revisiting the cluster-based paradigm for implicit search result diversification

To cope with ambiguous and/or underspecified queries, search result diversification (SRD) is a key technique that has attracted a lot of attention. This paper focuses on implicit SRD, where the subtopics underlying a query are unknown. Many existing methods appeal to the greedy strategy for generating diversified results. A common practice is using a heuristic criterion for making the locally optimal choice at each round. As a result, it is difficult to know whether the failures are caused by the optimization criterion or the setting of parameters. Different from previous studies, we formulate implicit SRD as a process of selecting and ranking k exemplar documents through integer linear programming (ILP). The key idea is that: for a specific query, we expect to maximize the overall relevance of the k exemplar documents. Meanwhile, we wish to maximize the representativeness of the selected exemplar documents with respect to the non-selected documents. Intuitively, if the selected exemplar documents concisely represent the entire set of documents, the novelty and diversity will naturally arise. Moreover, we propose two approaches ILP4ID (Integer Linear Programming for Implicit SRD) and AP4ID (Affinity Propagation for Implicit SRD) for solving the proposed formulation of implicit SRD. In particular, ILP4ID appeals to the strategy of bound-and-branch and is able to obtain the optimal solution. AP4ID being an approximate method transforms the target problem as a maximum-a-posteriori inference problem, and the message passing algorithm is adopted to find the solution. Furthermore, we investigate the differences and connections between the proposed models and prior models by casting them as different variants of the cluster-based paradigm for implicit SRD. To validate the effectiveness and efficiency of the proposed approaches, we conduct a series of experiments on four benchmark TREC diversity collections. The experimental results demonstrate that: (1) The proposed methods, especially ILP4ID, can achieve substantially improved performance over the state-of-the-art unsupervised methods for implicit SRD. (2) The initial runs, the number of input documents, query types, the ways of computing document similarity, the pre-defined cluster number and the optimization algorithm significantly affect the performance of diversification models. Careful examinations of these factors are highly recommended in the development of implicit SRD methods. Based on the in-depth study of different types of methods for implicit SRD, we provide additional insight into the cluster-based paradigm for implicit SRD. In particular, how the methods relying on greedy strategies impact the performance of implicit SRD, and how a particular diversification model should be fine-tuned.     

Core issues in pricing models for scholarly journals: a qualitative overview

Rhetoric about the ideal pricing model for scholarly content is often both strident and ill‐informed. Recognition of the nature of the business model is sometimes overlooked in favour of slogans or blanket accusations. This paper reviews qualitatively some of the core issues surrounding the creation of a sustainable pricing model that will enable authors, readers, and publishers to coexist. No particular examples are recommended or rejected; what is important is that interested parties explore thoroughly the available options and make decisions based on available facts, instead of emotion or trends.     

Intra-task variability of trunk coordination during a rate-controlled bipedal dance jump

In this study, we investigated trunk coordination during rate-controlled bipedal vertical dance jumps. The aims of the study were to investigate the pattern of coordination and the magnitude of coordination variability within jump phases and relative to phase-defining events during the jump. Lumbar and thoracic kinematics were collected from seven dancers during a series of jumps at 95 beats per minute. The vector coding technique was used to quantify the pattern and variability of trunk coordination. Coordination was predominantly anti-phase during propulsion and landing. Mean coordination variability peaked just before the landing phase and at the transition from landing to propulsion phases, and was lowest during the propulsion phase just before toe-off. The results indicate that peaks in variability could be explained by task and phase-specific biomechanical demands.     

Between training and popularization: Regulating science textbooks in secondary education

Recruitment into the scientific community is one oft-stated goal of science education--in the post-Sputnik United States, for example--but this obscures the fact that science textbooks are often read by people who will never be scientists. It cannot be presupposed that science textbooks for younger audiences, students in primary and secondary schools, function in this way. For this reason, precollegiate-level science textbooks are sometimes discussed as a subset of literature popularizing science. The high school science classroom and the textbook are forums for exposing the public to science. The role of governments and educational institutions in regulating the consumption of these texts not only determines which books are used; it influences how they are written, read, and deemed authoritative. Therefore such science textbooks should not be seen as (at best) the disjunction of texts-for-training and books-for-popularization. A changing sense of what "textbooks" are compels a different understanding of their use in the history of science.     

Getting Generation Y to attend: Friends,interactivity and half-time entertainment

People from Generation Y, given their number and stage in the family life-cycle, represent a key emerging audience for major sports. The study focussed on the effect of friends and half time enhancements on likely attendance at matches. The sport domain was the Australian Football League (AFL), the elite Australian rules football competition. The enhancements being tested were half-time entertainments based on performers from well-known television talent shows, Australian Idol and It Takes Two. Scenarios with and without interactive participation, based on short messaging service (SMS) messages, were tested. The study used a general population sample of 909 Generation Y people in a traditional AFL market and one where AFL is not the major winter competition. Previous attendance and sport orientation were the major influences on attendance at major sports, including the AFL. Friends influenced likely attendance at a game, but no effects were found for half-time entertainments. People who attended matches with friends typically had social activities before and after the game. This suggested that one promotional strategy to expand existing markets was to find and engage the social networks of existing fans, making sport attendance a broader part of an overall social event.     

The Dedisciplining of Peer Review

The demand for greater public accountability is changing the nature of ex ante peer review at public science agencies worldwide. Based on a four year research project, this essay examines these changes through an analysis of the process of grant proposal review at two US public science agencies, the National Institutes of Health (NIH) and the National Science Foundation (NSF). Weaving historical and conceptual narratives with analytical accounts, we describe the ways in which these two agencies struggle with the question of incorporating considerations of societal impact into the process of peer review. We use this comparative analysis to draw two main conclusions. First, evaluation of broader societal impacts is not different in kind from evaluation of intellectual merit. Second, the scientific community may actually bolster its autonomy by taking a broader range of considerations into its peer review processes.     

Instructional Tasks and the Development of Student Capacity to Think and Reason: An Analysis of the Relationship between Teaching and Learning in a Reform Mathematics Project

Abstract

In the present study the relationship between teaching and learning was examined using a conceptual framework that links dimensions of instructional tasks with gains in student learning outcomes. The greatest student gains on a performance assessment consisting of tasks that require high levels of mathematical thinking and reasoning were related to the use of instructional tasks that engaged students in the “doing of mathematics” or the use of procedures with connections to meaning. In addition, student performance gains were greater for those sites whose tasks were both set up and implemented to encourage the use of multiple solution strategies, multiple representations, and explanations. Whereas, student performance gains were relatively small for those sites whose tasks tended to be both set up and implemented in a procedural manner and that required a single solution strategy, single representations, and little or no mathematical communication.     

Predicting Robust Learning With the Visual Form of the Moment-by-Moment Learning Curve

We present a new method for analyzing a student's learning over time for a specific skill: analysis of the graph of the student's moment-by-moment learning over time. Moment-by-moment learning is calculated using a data-mined model that assesses the probability that a student learned a skill or concept at a specific time during learning (Baker, Goldstein, & Heffernan, 2010 Baker, R. S. J. d., Goldstein, A. B. and Heffernan, N. T. 2010. “Detecting the moment of learning”. In Proceedings of the 10th Annual Conference on Intelligent Tutoring Systems 25–34. In V. Aleven, J. Kay, & J. Mostow (Eds.),pp.Heidelberg, Germany: Springer.[Crossref] , [Google Scholar], 2011). Two coders labeled data from students who used an intelligent tutoring system for college genetics. They coded in terms of 7 forms that the moment-by-moment learning curve can take. These labels are correlated to test data on the robustness of students’ learning. We find that different visual forms are correlated with very different learning outcomes. This work suggests that analysis of moment-by-moment learning curves may be able to shed light on the implications of students’ different patterns of learning over time.     

'I Caught the Sudden Look of Some Dead Master': Eliot's Tradition and Modern Materialism

This essay explores the relations between T. S. Eliot's concept of tradition and the ‘modern materialism’ of Walter Benjamin, Jacques Lacan and Louis Althusser, and considers the implications of this resonance for both Eliot's critical legacy and the Marxist tradition. Initially surveying the critical controversy surrounding the canonical figure of Eliot and recent attempts to reconcile his avant-garde poetics with his reactionary social thought, the essay traces the roots of Eliot's tradition in a Nietzschean critique of historicism and its development into a theory of culture. Eliot's persistent drive towards impersonality echoes (and problematises) the efforts of Benjamin, Lacan and Althusser to construct a model of the social process that incorporates the unconscious. Rather than ultimately determining a set of political positions, the ‘missed encounter’ between Eliot's tradition and ‘modern materialism’ draws to light the Hegelian historicisms that haunt materialist theories of culture.