Output-sensitive autocompletion search     

Holger Bast  Christian W. Mortensen  Ingmar Weber 《Information Retrieval》2008,11(4):269-286

We consider the following autocompletion search scenario: imagine a user of a search engine typing a query; then with every keystroke display those completions of the last query word that would lead to the best hits, and also display the best such hits. The following problem is at the core of this feature: for a fixed document collection, given a set D of documents, and an alphabetical range W of words, compute the set of all word-in-document pairs (w, d) from the collection such that w ∈ W and d ∈ D. We present a new data structure with the help of which such autocompletion queries can be processed, on the average, in time linear in the input plus output size, independent of the size of the underlying document collection. At the same time, our data structure uses no more space than an inverted index. Actual query processing times on a large test collection correlate almost perfectly with our theoretical bound.

Ingmar WeberEmail:

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Radicalism in composition pedagogy     

Axel Polleres  Holger Lausen  Rubén Lara 《Academic Questions》1992,5(2):76-80

For the Record

Radicalism in composition pedagogy  相似文献   

Einstellungen,Motivation und Selbstwirksamkeit von Lehrkräften     

Britta Oerke  Nele McElvany  Annika Ohle-Peters  Holger Horz  Mark Ullrich 《Zeitschrift für Erziehungswissenschaft》2018,21(4):793-815

Teachers’ attitudes, motivation and self-efficacy are aspects of their professional competence affecting students’ motivation and learning via instructional behavior. In the present study, school type-specific differences in these teacher competencies and their relation to instruction when teaching with texts and integrated pictures are analyzed, further focusing on effects of school subject and teaching experience. Teachers (N?=?265) of primary school, lower and upper track secondary school filled in questionnaires. Primary school teachers were less intrinsically motivated to teach text-picture integration than secondary school teachers. They showed more negative attitudes towards texts with pictures than upper track teachers and avoided discussing the picture to a higher degree. All teacher characteristics predicted instructional behavior, further school type-specific effects of the subject occurred. The results provide starting points for teacher training and the potential for further research concerning the support of students in class.  相似文献   

Letter to the editor concerning the article “Effects of acoustic feedback training in elite-standard Para-Rowing” by Schaffert and Mattes (2015)     

Holger Hill 《Journal of sports sciences》2015,33(15):1637-1638

In a case study, Schaffert and Mattes reported the application of acoustic feedback (sonification) to optimise the time course of boat acceleration. The authors attributed an increased boat speed in the feedback condition to an optimised boat acceleration (mainly during the recovery phase). However, in rowing it is biomechanically impossible to increase the boat speed significantly by reducing the fluctuations in boat acceleration during the rowing cycle. To assess such a, potentially small, optimising effect experimentally, the confounding variables must be controlled very accurately (that is especially the propulsive forces must be kept constant between experimental conditions or the differences in propulsive forces between conditions must be much smaller than the effects on boat speed resulting from an optimised movement pattern). However, this was not controlled adequately by the authors. Instead, the presented boat acceleration data show that the increased boat speed under acoustic feedback was due to increased propulsive forces.  相似文献   

Improved Student Reasoning About Carbon-Transforming Processes Through Inquiry-Based Learning Activities Derived from an Empirically Validated Learning Progression     

J. W. Schramm  H. Jin  E. G. Keeling  M. Johnson  H. J. Shin 《Research in Science Education》2018,48(5):887-911

This paper reports on our use of a fine-grained learning progression to assess secondary students’ reasoning through carbon-transforming processes (photosynthesis, respiration, biosynthesis). Based on previous studies, we developed a learning progression with four progress variables: explaining mass changes, explaining energy transformations, explaining subsystems, and explaining large-scale systems. For this study, we developed a 2-week teaching module integrating these progress variables. Students were assessed before and after instruction, with the learning progression framework driving data analysis. Our work revealed significant overall learning gains for all students, with the mean post-test person proficiency estimates higher by 0.6 logits than the pre-test proficiency estimates. Further, instructional effects were statistically similar across all grades included in the study (7th–12th) with students in the lowest third of initial proficiency evidencing the largest learning gains. Students showed significant gains in explaining the processes of photosynthesis and respiration and in explaining transformations of mass and energy, areas where prior research has shown that student misconceptions are prevalent. Student gains on items about large-scale systems were higher than with other variables (although absolute proficiency was still lower). Gains across each of the biological processes tested were similar, despite the different levels of emphasis each had in the teaching unit. Together, these results indicate that students can benefit from instruction addressing these processes more explicitly. This requires pedagogical design quite different from that usually practiced with students at this level.  相似文献   

International research networks: Determinants of country embeddedness     

Holger Graf  Martin Kalthaus 《Research Policy》2018,47(7):1198-1214

Research activities are increasingly global so that embeddedness in international knowledge networks is decisive for inventive and innovative performance. We analyze determinants of countries’ embeddedness in the global photovoltaics knowledge network for the period 1980–2015 and argue that positions in this network are determined by the structure and functionality of national research systems and by instruments within the policy-mix for renewable energies. We show that cohesion and connectedness of the national research system positively affect international embeddedness, whereas centralized systems are detrimental to embeddedness. This indicates that a diffusion oriented research system allows better access to international knowledge flows. Policy instruments, especially demand side instruments, show a positive effect on embeddedness.  相似文献