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Objective: To determine whether information retrieval might be enhanced by making each component of a structured abstract a separately searchable field. Design: Parallel searches on records arranged so that each abstract could either be searched in its entirety or as a collection of structured fields. Subjects: Records about cardiovascular disease downloaded from MEDLINE and tested against clinical questions derived from a concurrent survey of CD-ROM use in three health science libraries. Intervention: The investigators identified terms used to structure abstracts on MEDLINE and imported the abstracts into an Idealist database prior to searching using keywords from clinical questions. Measurements and main results: recall and precision rates are given for each question in the ‘structured’ and the ‘unstructured’ set of records. Conclusions: Use of structured, rather than unstructured, abstracts improves precision at the ex-pense of recall and places heavier demands upon the searcher’s skill in choosing the correct fields within the abstract to search. Further investigation requires more accurate simulation of MEDLINE software that utilizes features such as MeSH terms, explode, facilities and delimiters.  相似文献   
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ABSTRACT

The length of telomeres is an objective measure of biologic ageing. This study evaluated the extent minutes of walking per week are associated with leukocyte telomere length (LTL) in a random sample of 5,823 U.S. adults. The investigation was cross-sectional and data were obtained from the National Health and Nutrition Examination Survey (NHANES). LTL was measured by the quantitative polymerase chain reaction method. Walking minutes was calculated from walking frequency and duration measures. Results showed that for each year of chronological age, telomeres were 15.6 base pairs shorter (P < 0.0001). With walking minutes and LTL treated as continuous variables, the relationship was quadratic, not linear (F = 11.2, P = 0.0023). With walking time divided into three categories, adults who performed ≥ 150 minutes of walking per week had longer telomeres than those who did no regular walking, and those who did some, but less than the recommendation (F = 5.0, P = 0.0137). Regular walkers were estimated to have a biologic ageing advantage associated with 6.5–7.6 years less biologic ageing compared to non-walkers, after adjusting for covariates. Additional investigations designed to study causality and the mechanisms associated with the walking and LTL relationship are needed.  相似文献   
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The field of educational measurement has evolved considerably since the first doctoral programs were established. In response, programs have typically tacked on courses that address newly developed theories, methods, tools, and techniques. As our review of current programs evidences, this approach produces artificial distinctions among topics and techniques that are in fact a tightly coupled whole. This position paper advocates a redesign of the scope and sequence for doctoral programs focused on the preparation of the next generations of educational measurement specialists; a redesign that reflects the full life‐cycle of instrument development and use.  相似文献   
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Abstract

This paper involves a search for interracial entanglements in South African sport and considers how these experiences may be narrated. The paper comprises three sections. The first provides an overview of traditional narratives of apartheid and apartheid sport that focus on race as a perpetual marker of social division. The second section shifts attention to the gaps, blind spots, mistakes, paradoxes, ironies, anomalies, ambiguities and invisibilities in the structures of apartheid that allowed for racial encounters and entanglements. The paper concludes with a discussion about the methodological and political implications of incorporating racial entanglements into narratives of apartheid sport.  相似文献   
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Elementary and secondary students spend more hours outside of class than in formal school and thus have more time for interaction with everyday science. However, evidence from a large international survey, Program of International Student Assessment (PISA) (OECD 2012), found a negative relationship between number of hours attending after-school science and science assessment scores in many countries, raising questions about why. The secondary analysis of the 2006, 2009, and 2012 PISA surveys found that in most Western countries the longer students attended after-school science programs (in a typical week), the lower their PISA standardized science test score, but the higher their positive attitudes toward future science careers, interest in science, and self-confidence in science. Several potential hypotheses for this relationship are examined and rejected. Further analysis of a causal relationship between frequent attendance in after-school programs and student achievement and attitudes should clearly identify the content of the program so that the analysis could distinguish experiences closely related to regular school curricula from the informal science activities that are not. A new analysis also should include carefully designed longitudinal surveys to test the effectiveness of informal experiences on later life choices in career and study.  相似文献   
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This study describes one teacher's use of multimedia, specifically CD-ROM talking books, in the classroom. The goal of the investigation was to reveal and analyse how a primary (Grade 3) teacher integrated CD-ROM books into her curriculum. Issues emerging from the study included how features of the software interact with features of classrooms, how patterns of instruction are affected by the infusion of technology, and how students interact with the software, and each other, while reading the CD- ROM books  相似文献   
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The purpose of the study was to investigate faculty perceptions of student evaluative information collected by three methods: objective questionnaire items, open-ended questions, and group interviews. Faculty rated three simulated evaluation reports on their potential for accuracy, trustworthiness, usefulness, comprehensiveness, believability, interpretability, and value as information used for self-improvement and promotion purposes. Faculty, in general, regarded the evaluative information to be more credible, useful, and accurate for their own self-improvement than for promotion purposes. Faculty also desired more than one type of evaluative information regardless of the purpose of evaluation.  相似文献   
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