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91.
Steven J. Sackett James M. Kelley Peter P. Gillis 《Journal of The Franklin Institute》1977,304(1):47-63
Using our constitutive theory for polycrystalline plasticity, we have calculated characteristic yield conditions for several sample materials in which the dependence of the dislocation velocity on stress is given by an empirical power function. The shape of the yield surfaces for these materials varies resembling that of von Mises when the stress exponent is small and that of Tresca when the exponent is large. Additional examples illustrate the ability of the proposed theory to model such phenomena as the development of anisotropy during plastic deformation, material hardening and softening, the occurrence of upper and lower yield points, and a Bauschinger effect. 相似文献
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Epshteyn AA Maher S Taylor AJ Holton AB Borenstein JT Cuiffi JD 《Biomicrofluidics》2011,5(4):46501-465016
The design and fabrication of a membrane-integrated microfluidic cell culture device (five layers,≤500 μm total thickness) developed for high resolution microscopy is reported here. The multi-layer device was constructed to enable membrane separated cell culture for tissue mimetic in vitro model applications and pharmacodynamic evaluation studies. The microdevice was developed via a unique combination of low profile fluidic interconnect design, substrate transfer methodology, and wet silane bonding. To demonstrate the unique high resolution imaging capability of this device, we used oil immersion microscopy to image stained nuclei and mitochondria in primary hepatocytes adhered to the incorporated membrane 相似文献
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In this review, we examine the original obesity paradox phenomenon (i.e. in cardiovascular disease populations, obese patients survive better), as well as three other related paradoxes (pre-obesity, "fat but fit" theory, and "healthy" obesity). An obesity paradox has been reported in a range of cardiovascular and non-cardiovascular conditions. Pre-obesity (defined as a body mass index of 25.0-29.9 kg · m?2) presents another paradox. Whereas "overweight" implies increased risk, it is in fact associated with decreased mortality risk compared with normal weight. Another paradox concerns the observation than when fitness is taken into account, the mortality risk associated with obesity is offset. The final paradox under consideration is the presence of a sizeable subset of obese individuals who are otherwise healthy. Consequently, a large segment of the overweight and obese population is not at increased risk for premature death. It appears therefore that low cardiorespiratory fitness and inactivity are a greater health threat than obesity, suggesting that more emphasis should be placed on increasing leisure time physical activity and cardiorespiratory fitness as the main strategy for reducing mortality risk in the broad population of overweight and obese adults. 相似文献
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Journal of Science Education and Technology - In this paper, the effectiveness of training faculty in laboratory teaching (the teaching of science in a laboratory setting using experiments and... 相似文献
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Steven A. Yourstone Robert J. Tepper 《Decision Sciences Journal of Innovative Education》2014,12(4):321-338
Although originally designed for science courses, learning studios have been introduced at over 100 college campuses in a variety of disciplines. Our study focuses on the differences between classrooms designed as lecture spaces versus classrooms designed as learning studios. The impetus is the growing number of learning studios and proponents’ claim of better collaboration and learning within them. Given the substantial cost of a learning studio and greater demand at the authors’ university than supply, we questioned whether the university administration should be encouraged to build more. Learning studios are classrooms in which the seating arrangement places the students in a face‐to‐face orientation with one another. Our study measures the differences between learning studios and traditional classrooms both quantitatively and qualitatively. The learning studio did not result in higher retention rates (the percentage of students completing the course during the semester) or significant differences in total points earned by students in a learning studio compared to a traditional classroom. When examined by gender, however, a significant difference in total points is apparent. For all students in the study, the ability to interact with other students as well as the instructor was greater in the learning studio. 相似文献
100.
Steven W. Gilbert 《科学教学研究杂志》1989,26(4):315-327
Teaching materials with extensive analogies, similes, and metaphors were written for two high-school biology units. Their effect on learning and attitude was assessed by a comparison to students using a literal version of the same text. Little was found to support the contention that the use of these systems increases student achievement, and there was some indication that they may have a negative effect on student attitudes. 相似文献