The effects of static stretching on speed and agility: One or multiple repetition protocols?     

Alexandra Avloniti  Ioannis G. Fatouros  Maria Protopapa  Ioannis Athanailidis  Christina Avloniti 《European Journal of Sport Science》2016,16(4):402-408

Although static stretching (SS) is utilized during warm-up before training and competition, the results about its effects on performance remain controversial. We examined whether performing a stretch of short-to-moderate duration (<60 sec) in a single repetition produces a similar or different effect on speed and agility performance from the effect which is produced while performing the same stretch in multiple repetitions of the same total duration. According to a repeated measurement design, 40 trained males were randomly assigned to either (1) a single repetition group or (2) a multiple repetition group. The participants in each group performed five trials: a control trial (no stretches were performed) and four experimental trials of SS protocols consisting of five exercises performed at either 20 sec (2 × 10 in the second group), 30 sec (3 × 10 in the second group), 40 sec (4 × 10 in the second group) or 60 sec (6 × 10 in the second group) of total duration. A two-way repeated measures analysis of variance showed that the participants in both group improved their speed performance in response to the 20-sec trial, whereas agility remained unaffected. Data analysis also revealed that the repetition number did not affect speed and agility performance. These data suggest that SS of short duration (<30 sec) may actually improve acute speed performance, whereas SS of moderate duration may not hamper speed and agility performance. Moreover, the effects of SS protocols are related to the total duration of each exercise and not to the number of repetitions in which each exercise is performed.  相似文献   

One hundred and fifty years of sprint and distance running – Past trends and future prospects     

Martin Weiss  Alexandra Newman  Ceri Whitmore  Stephan Weiss 《European Journal of Sport Science》2016,16(4):393-401

Sprint and distance running have experienced remarkable performance improvements over the past century. Attempts to forecast running performances share an almost similarly long history but have relied so far on relatively short data series. Here, we compile a comprehensive set of season-best performances for eight Olympically contested running events. With this data set, we conduct (1) an exponential time series analysis and (2) a power-law experience curve analysis to quantify the rate of past performance improvements and to forecast future performances until the year 2100. We find that the sprint and distance running performances of women and men improve exponentially with time and converge at yearly rates of 4% ± 3% and 2% ± 2%, respectively, towards their asymptotic limits. Running performances can also be modelled with the experience curve approach, yielding learning rates of 3% ± 1% and 6% ± 2% for the women's and men's events, respectively. Long-term trends suggest that: (1) women will continue to run 10–20% slower than men, (2) 9.50 s over 100 m dash may only be broken at the end of this century and (3) several middle- and long-distance records may be broken within the next two to three decades. The prospects of witnessing a sub-2 hour marathon before 2100 remain inconclusive. Our results should be interpreted cautiously as forecasting human behaviour is intrinsically uncertain. The future season-best sprint and distance running performances will continue to scatter around the trends identified here and may yield unexpected improvements of standing world records.  相似文献   

Theory of mind in dogs?: examining method and concept     

Horowitz A 《Learning & behavior》2011,39(4):314-317

In line with other research, Udell, Dorey, and Wynne’s (in press) finding that dogs and wolves pass on some trials of a putative theory-of-mind test and fail on others is as informative about the methods and concepts of the research as about the subjects. This commentary expands on these points. The intertrial differences in the target article demonstrate how critical the choice of cues is in experimental design; the intersubject-group differences demonstrate how life histories can interact with experimental design. Even the best-designed theory-of-mind tests have intractable logical problems. Finally, these and previous research results call for the introduction of an intermediate stage of ability, a rudimentary theory of mind, to describe subjects’ performance.  相似文献   

Toward an Integrated Framework of Multiple Text Use     

Alexandra List 《教育心理学家》2019,54(1):20-39

We introduce the Integrated Framework of Multiple Texts to understand how students use and form connections between multiple texts to accomplish personal or task goals. The Integrated Framework of Multiple Texts conceptualizes students’ multiple text use as unfolding over the course of three stages—preparation, execution, and production. In the preparation stage of the framework, individual difference factors and students’ task analysis result in learners’ adoption of a default stance, or a general orientation, toward multiple text use. During the execution stage of the framework, students engage in a variety of behavioral, cognitive, and metacognitive/regulatory strategies to develop cross-textual links and to integrate information across multiple texts. The execution stage concludes with students’ development of a variety of affective and cognitive outcomes as a consequence of text access. Finally, in the production stage of the framework, students draw on these affective and cognitive outcomes to develop external, often written products.  相似文献   

Black School,White School: Racism and Educational (Mis)Leadership. Jeffrey S. Brooks. New York,NY: Teachers College Press, 2012, 153 pp., $28.95     

Lucy E. Bailey  Alexandra J. Holter 《Educational Studies A Journal of the American Educational Studies Association》2016,52(4):381-384

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Digital Work Practices: Affordances in Design Education     

Alexandra Crosby  Kane Pham  J. Fiona Peterson  Thomas Lee 《The International Journal of Art & Design Education》2020,39(1):22-37

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Ulla de Stricker, Jill Hurst-Wahl, Editors , The Information and Knowledge Professional's Career Handbook: Define and Create Your Success, Chandos Publishing, Oxford (2011)283 pp. $80.00.     

Alexandra Simons 《The Journal of Academic Librarianship》2011,37(5):450

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Evaluation of evidence-based medicine search skills in the clinical years     

Linton AM  Wilson PH  Gomes A  Abate L  Mintz M 《Medical reference services quarterly》2004,23(2):21-31

The librarians of the Health Sciences Library worked with the director of the Primary Care Clerkship to reinforce the principles of Evidence-Based Medicine (EBM) searching, taught during the first two years of medical school, through an intensive workshop. The purpose of the program was to ensure that students apply EBM principles in a timely and effective manner in clinical situations. Working in teams led by a resident and librarian, students researched real cases and then evaluated the effectiveness of their approach to the problems. This paper outlines the rationale for the team approach, reviews the administration of a computer-based workshop, and discusses the evaluation process. Evaluation focused on both the current workshop and its implications for the informatics program presented to students during years one and two.  相似文献   

Isolation and enrichment of low abundant particles with insulator-based dielectrophoresis     

Alexandra LaLonde  Maria F. Romero-Creel  Mario A. Saucedo-Espinosa  Blanca H. Lapizco-Encinas 《Biomicrofluidics》2015,9(6)

Isolation and enrichment of low-abundant particles are essential steps in many bio-analytical and clinical applications. In this work, the capability of an insulator-based dielectrophoresis (iDEP) device for the detection and stable capture of low abundant polystyrene particles and yeast cells was evaluated. Binary and tertiary mixtures of particles and cells were tested, where the low-abundant particles had concentration ratios on the order of 1:10 000 000 compared to the other particles present in the mixture. The results demonstrated successful and stable capture and enrichment of rare particles and cells (trapping efficiencies over 99%), where particles remained trapped in a stable manner for up to 4 min. A device with four reservoirs was employed for the separation and enrichment of rare particles, where the particles of interest were first selectively concentrated and then effectively directed to a side port for future collection and analysis. The present study demonstrates that simple iDEP devices have appropriate screening capacity and can be used for handling samples containing rare particles; achieving both enrichment and isolation of low-abundant particles and cells.  相似文献   

Constructing the academic category of teacher educator in universities’ recruitment processes in Aotearoa,New Zealand     

Alexandra C. Gunn  David Berg  Mary F. Hill  Mavis Haigh 《师资教育杂志》2015,41(3):307-320

An examination of recruitment materials and interviews with personnel involved in the employment of teacher educators to positions in university-based New Zealand initial teacher education (ITE) courses reveals three constructions of teacher educator as academic worker: the professional expert, the dually qualified, and the traditional academic. However, this study’s analysis shows how these constructions allow universities to pursue a bifurcated approach for the employment of teacher educators, an approach that maintains binaries within teacher education and hinders development in the field. Furthermore, as the spectre of a major cultural shift in the provision of New Zealand ITE arises, the extent to which the professional expert and traditional academic constructions of teacher educator might serve the scope of work required of postgraduate ITE going forth is questioned.  相似文献