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排序方式: 共有166条查询结果,搜索用时 687 毫秒
1.
Kristina L. Kendall David H. Fukuda Parker N. Hyde Abbie E. Smith-Ryan Jordon R. Moon Jeffrey R. Stout 《Journal of sports sciences》2017,35(7):624-633
The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers. METHODS: Twenty-three elite-level male rowers (mean± SD; age 24.6 ± 2.2 years; stature: 191.4 ± 7.2 cm; mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM. 相似文献
2.
Researchers in the field of gifted education are becoming increasingly aware that a variety of research approaches can make contributions to research on giftedness. This paper describes task analysis, a research methodology derived from counseling process research. Task analysis appears to be a useful research approach for building theoretical models of how therapeutic and educational interventions can facilitate positive changes in gifted children. The paper traces the historical development of task analysis methodology, describes the steps involved in conducting a rational‐empirical task analysis of change processes, and provides an example of how task analysis methodology might be applied to investigations of change processes in the field of gifted education. 相似文献
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Nancy L. Halliday Mary B. Moon Daniel L. O'Donoghue Britta M. Thompson Sheila M. Crow 《Anatomical sciences education》2019,12(4):399-406
The University of Oklahoma College of Medicine has conducted an annual Anatomical Donor Luncheon where families of the anatomical donors met anatomy dissection groups of medical students. The luncheon presented an opportunity for donor family members to share the life story of their loved one with the medical students prior to the start of the anatomy course. This study was designed to understand the impact of the Anatomical Donor Luncheon on families of the donors. Seven families in two different focus groups were included to explore the reactions and attitudes of the donor families to meeting the medical students. Conversations were digitally recorded and transcribed. Qualitative analysis of textual data were coded by three investigators using the Constant Comparative Method. To provide evidence of validity, a form of member checking was utilized. For further triangulation, an analyst not involved in conducting the focus groups or analyzing the data, re-coded all data. This analyst used categories and themes identified by the original analysts, ensuring validity of the themes and any negative cases (data not supporting or contradictory of the established categories and themes). One meta-theme and three sub-themes were identified. The meta-theme was Donor Family Participants Experience Transformation and Closure, and sub-themes were Motivators for Participation, Optimal Venue Factors, and Optimal Medical Student–Anatomical Donor Family Interactions. Study findings indicated the Anatomical Donor Luncheon facilitated closure on the death of their loved one, and transformed their apprehension about the luncheon and body donation into an attitude of gratitude and appreciation. 相似文献
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Equations for the calculation of radiant power F through two apertures in series are well known. A characteristic of these formulae is that they give F as a small difference between two large terms. Evidently, the flux through the apertures must decrease as the spacing between them increases; and for large spacing, the inverse-square relation must hold. Instead of exhibiting this behaviour in an obvious manner, however, the traditional equations give the specious impression of an increase in F with increase in spacing. The paper develops an approximate formulae that applies to apertures in the shape of any regular polygon and that shows clearly how the inverse square relation is approached for large separation. 相似文献
7.
Mass transport in porous materials is universal in nature, and its worth attracts great attention in many engineering applications. Plant leaves, which work as natural hydraulic pumps for water uptake, have evolved to have the morphological structure for fast water transport to compensate large water loss by leaf transpiration. In this study, we tried to deduce the advantageous structural features of plant leaves for practical applications. Inspired by the tissue organization of the hydraulic pathways in plant leaves, analogous double-layered porous models were fabricated using agarose hydrogel. Solute transport through the hydrogel models with different thickness ratios of the two layers was experimentally observed. In addition, numerical simulation and theoretical analysis were carried out with varying porosity and thickness ratio to investigate the effect of structural factors on mass transport ability. A simple parametric study was also conducted to examine unveiled relations between structural factors. As a result, the porosity and thickness ratio of the two layers are found to govern the mass transport ability in double-layered porous materials. The hydrogel models with widely dispersed pores at a fixed porosity, i.e., close to a homogeneously porous structure, are mostly turned out to exhibit fast mass transport. The present results would provide a new framework for fundamental design of various porous structures for effective mass transport. 相似文献
8.
In this study, we simulated deformation and surfactant distribution on the interface of a surfactant-covered droplet using optical tweezers as an external source. Two optical forces attracted a single droplet from the center to both sides. This resulted in an elliptical shape deformation. The droplet deformation was characterized as the change of the magnitudes of surface tension and optical force. In this process, a non-linear relationship among deformation, surface tension, and optical forces was observed. The change in the local surfactant concentration resulting from the application of optical forces was also analyzed and compared with the concentration of surfactants subjected to an extensional flow. Under the optical force influence, the surfactant molecules were concentrated at the droplet equator, which is totally opposite to the surfactants behavior under extensional flow, where the molecules were concentrated at the poles. Lastly, the quasi-equilibrium surfactant distribution was obtained by combining the effects of the optical forces with the extensional flow. All simulations were executed by the lattice Boltzmann method which is a powerful tool for solving micro-scale problems. 相似文献
9.
This paper completes our treatment of radiant flux through pairs of apertures. In Part II, we obtained approximate equations for rectangular apertures in parallel planes, with the restriction that two apertures be identical and that one be directly above the other. Here we generalize to the case of any apertures that fit into a rectangular grid. The idea for this generalization originated with Ondracek but it is here expressed in matrix notation, which allows coefficients Fij to be obtained rather simply. 相似文献
10.
Forward citations of patents have been used extensively to capture the impact of technological knowledge. However, our understanding of the factors shaping patent citation patterns remains limited. One of the main limitations is the lack of scholarly attention paid to the dynamic influences arising from the evolution of technology fields. From an evolutionary perspective, technological impact is not simply determined by the static attributes of a technology itself; it is also dynamically affected by changes in the external conditions. Drawing on this viewpoint, this study suggests a model for understanding patent citation patterns by reflecting the evolution of the technology fields to which each patent belongs. Four such factors are explored: technology cycle time, potential of technological convergence, popularity of the technology field, and technological novelty. Based on the proposed model, we show how expected citation patterns can change as a result of different scenarios for technology field evolution. We conduct a case study of patents in the information technology and healthcare industries to show citation patterns of patents across heterogeneous industries as well as those within an industry. Contributions to the innovation literature and research investment decisions are discussed. 相似文献