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Amador García-Ramos Belén Feriche Alejandro Pérez-Castilla Paulino Padial Slobodan Jaric 《European Journal of Sport Science》2017,17(6):690-698
This study aimed to explore the strength of the force–velocity (F–V) relationship of lower limb muscles and the reliability of its parameters (maximum force [F0], slope [a], maximum velocity [V0], and maximum power [P0]). Twenty-three men were tested in two different jump types (squat and countermovement jump: SJ and CMJ), performed under two different loading conditions (free weight and Smith machine: Free and Smith) with 0, 17, 30, 45, 60, and 75?kg loads. The maximum and averaged values of F and V were obtained for the F–V relationship modelling. All F–V relationships were strong and linear independently whether observed from the averaged across the participants (r?≥?0.98) or individual data (r?=?0.94–0.98), while their parameters were generally highly reliable (F0 [CV: 4.85%, ICC: 0.87], V0 [CV: 6.10%, ICC: 0.82], a [CV: 10.5%, ICC: 0.81], and P0 [CV: 3.5%, ICC: 0.93]). Both the strength of the F–V relationships and the reliability of their parameters were significantly higher for (1) the CMJ over the SJ, (2) the Free over the Smith loading type, and (3) the maximum over the averaged F and V variables. In conclusion, although the F–V relationships obtained from all the jumps tested were linear and generally highly reliable, the less appropriate choice for testing the F–V relationship could be through the averaged F and V data obtained from the SJ performed either in a Free weight or in a Smith machine. Insubstantial differences exist among the other combinations tested. 相似文献
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Elizabeth Shaunessy Patricia Alvarez McHatton Claire Hughes Alejandro Brice Mary Ann Ratliff 《Roeper Review》2013,35(3):174-182
Eight gifted and eight general‐education students engaged in discussions regarding their observations of, experiences in, and recommendations for education. Six categories emerged through qualitative analysis of their conversations. These categories include: problem solving, task commitment, self‐perceptions, education, communication, and discrimination. Content within each category provides a glimpse into the students’ perceptions of their schooling experiences. The roles of ethnic identity development, identification with majority culture, adolescence, and gifted‐ness are examined and recommendations for future research are provided. 相似文献
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Méndez A Pérez C Montañéz JC Martínez G Aguilar CN 《Journal of Zhejiang University. Science. B》2011,12(12):961-968
The combined effects of pH and temperature on red pigment production and fungal morphology were evaluated in a submerged culture
of Penicillium purpurogenum GH2, using Czapek-Dox media with d-xylose as a carbon source. An experimental design with a factorial fix was used: three pH values (5, 7, and 9) and two temperature
levels (24 and 34 °C) were evaluated. The highest production of red pigment (2.46 g/L) was reached with a pH value of 5 and
a temperature of 24 °C. Biomass and red pigment production were not directly associated. This study demonstrates that P. purpurogenum GH2 produces a pigment of potential interest to the food industry. It also shows the feasibility of producing and obtaining
natural water-soluble pigments for potential use in food industries. A strong combined effect (p<0.05) of pH and temperature was associated with maximal red pigment production (2.46 g/L). 相似文献
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Alejandro Tiana 《Journal of Educational Change》2008,9(4):391-394
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Susan Clayton Jerry Luebke Carol Saunders Jennifer Matiasek Alejandro Grajal 《Environmental Education Research》2014,20(4):460-475
Societal response to climate change has been inadequate. A perception that the issue is both physically and temporally remote may reduce concern; concern may also be affected by the political polarization surrounding the issue in the USA. A feeling of connection to nature or to animals may increase personal relevance, and a supportive social context may counteract political tensions. Zoos may provide opportunities for both sense of connection and social support. We surveyed over 7000 zoo and aquarium visitors to examine the ways in which a feeling of personal connection among zoo visitors may encourage concern about climate change. Results show that feeling connected to animals at the zoo is significantly associated with cognitive and emotional responses to climate change, as well as with other social groupings and social responses. Overall, the zoo seems to present a supportive social context for considering the topic. 相似文献
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Alejandro Torrejón Carlos Balsalobre-Fernández G. Gregory Haff 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(3):245-255
This study aimed to determine the suitability of the load-velocity relationship to prescribe the relative load (%1RM) in women, as well as to compare the load-velocity profile between sexes and participants with different strength levels. The load-velocity relationship of 14 men (1RM: 1.17 ± 0.19) and 14 women (1RM: 0.66 ± 0.13) were evaluated in the bench press exercise. The main findings revealed that: (I) the load-velocity relationship was always strong and linear (R2 range: 0.987–0.993), (II) a steeper load-velocity profile was observed in men compared to women (Effect size [ES]: 1.09), with men showing higher velocities for light loads (ES: ? 0.81 and ? 0.40 for the y-intercept and 30%1RM, respectively), but women reporting higher velocities for the heavy loads (ES: 1.14 and 1.50 at 90%1RM and 100%1RM, respectively); and (III) while the slope of the load-velocity profile was moderately steeper for weak men compared to their strong counterpart (ES: 1.02), small differences were observed between strong and weak women (ES: ? 0.39). While these results support the use of the individual load-velocity relationship to prescribe the %1RM in the bench press exercise for women, they also highlight the large disparities in their load-velocity profile compared to men. 相似文献
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Paulo Volante Sergio Valenzuela Alejandro Díaz Magdalena Fernández Antonio Mladinic 《School Leadership & Management》2019,39(1):26-47
This study seeks to develop and validate an Assessment Centre (AC) tool for the evaluation and selection of school leaders, focusing on the identification of competencies that influence teaching and learning outcomes. International research supports the creation of Assessment Centres to select candidates for these roles, due to their superior predictive capacity over traditional methods. In this research, a model composed of four face-to-face instruments (an interview to assess competencies, a human resources exercise, a class observation exercise, and a strategic analysis exercise) was designed and validated which simulated the key tasks of a school principal. To establish the desired performance outcomes, three competencies and 15 indicators were selected, based on international and local standards. The analysis of performance results was obtained from a sample of 164 participants made up of teachers, school leaders and principals. The results suggest positive evidence for construct validity, concurrent criteria validity, and reliability between evaluators. Moreover, the data obtained from a sub-sample of principals, with three or more years of experience in their role, allowed for the association of their AC scores with the results of their school organisations, as measured by the National System for the Measurement of Educational Quality in the years 2013 and 2016. 相似文献