13,562 research outputs found

    Compressible flow structures interaction with a two-dimensional ejector: a cold-flow study

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    An experimental study has been conducted to examine the interaction of compressible flow structures such as shocks and vortices with a two-dimensional ejector geometry using a shock-tube facility. Three diaphragm pressure ratios ofP4 =P1 = 4, 8, and 12 have been employed, whereP4 is the driver gas pressure andP1 is the pressure within the driven compartment of the shock tube. These lead to incident shock Mach numbers of Ms = 1:34, 1.54, and 1.66, respectively. The length of the driver section of the shock tube was 700 mm. Air was used for both the driver and driven gases. High-speed shadowgraphy was employed to visualize the induced flowfield. Pressure measurements were taken at different locations along the test section to study theflow quantitatively. The induced flow is unsteady and dependent on the degree of compressibility of the initial shock wave generated by the rupture of the diaphragm

    Does the transition to grandparenthood influence the health and well-being of older people? Evidence from the CHARLS study in China.

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    •Transitioning to grandmotherhood was associated with a higher probability of reporting ≥1 functional limitations in ADLs.•Transitioning to grandparenthood was associated with higher life satisfaction.•Role enhancement and role strain may generate mixed impacts of transitioning to grandparenthood on older adults' health

    Systematic review of grounded theory studies in physiotherapy

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    Aim: This systematic review aimed at appraising the methodological rigor of grounded theory research published in the field of physiotherapy to assess how the methodology is understood and applied. A secondary aim was to provide research implications drawn from the findings to guide future grounded theory methodology research. Methods: A systematic search was conducted in MEDLINE, CINHAL, SPORT Discus, Science Direct, PubMed, Scopus and Web of Science to identify studies in the field of physiotherapy that reported using grounded theory methodology and/or methods in the study title and/or abstract. The descriptive characteristics and methodological quality of eligible studies were examined using the assessment guidelines developed by Hutchison, Johnston and Breckon (2011). Findings: The review included sixty-eight studies conducted between 1998 and 2017. The findings showed that grounded theory methodology is becoming increasingly used by physiotherapy researchers. Thirty-six studies (53%) demonstrated a good understanding and appropriate application of grounded theory methodology. Thirty-two studies (47%) presented descriptive findings and were considered to be of poor methodological quality. Conclusions: There are several key tenets of grounded theory methodology that are integral to the iterative process of qualitative theorizing and need to be applied throughout all research practices including sampling, data collection and analysis

    Electronic Instrumentation

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    Contains reports on status of research and three research projects.National Institutes of Health (Grant 1 505 FR07047-01)Electronic Instrumentation Group of the Research Laboratory of Electronics in research under NIH Grant 1 505 FR07047-0

    Assessment of economic factors affecting the satellite power system. Volume 2: The systems implications of rectenna siting issues

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    The feasibility was evaluated of finding potential sites for Solar Power Satellite (SPS) receiving antennas (rectennas) in the continental United States, in sufficient numbers to permit the SPS to make a major contribution to U.S. generating facilities, and to give statistical validity to an assessment of the characteristics of such sites and their implications for the design of the SPS system. It is found that the cost-optimum power output of the SPS does not depend on the particular value assigned to the cost per unit area of a rectenna and its site, as long as it is independent of rectenna area. Many characteristics of the sites chosen affect the optimum design of the rectenna itself

    Development and evaluation of an intervention to improve further education students' understanding of higher education assessment criteria: three studies

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    Three studies about helping Further Education students prepare for study at universityThis paper reports three studies about preparing Further Education (FE) students for the transition to Higher Education (HE) by improving their understanding of HE assessment criteria. In study 1, students and tutors in both FE and HE were interviewed for a qualitative analysis of their understandings and expectations about assessment criteria. In study 2, students in FE and HE completed questionnaires measuring self-rated understanding and ability about assessment criteria, and beliefs about essay writing. Studies 1 and 2 both showed that FE students were more confident than HE students about their understanding and ability in relation to assessment criteria, but FE students’ understandings suggested more surface approaches to learning and more naïve epistemological beliefs. In study 3, a workshop intervention to improve FE students’ understandings of HE assessment criteria was evaluated in a comparative longitudinal trial. The intervention reduced FE students’ self-rated understanding and ability, and promoted more sophisticated beliefs about essay writing, by comparison with students who received standard tuition. We concluded that interventions to develop more realistic understandings of what is required in academic writing could be used to prepare FE students more effectively for the transition to HE

    Tube Width Fluctuations in F-Actin Solutions

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    We determine the statistics of the local tube width in F-actin solutions, beyond the usually reported mean value. Our experimental observations are explained by a segment fluid theory based on the binary collision approximation (BCA). In this systematic generalization of the standard mean-field approach effective polymer segments interact via a potential representing the topological constraints. The analytically predicted universal tube width distribution with a stretched tail is in good agreement with the data.Comment: Final version, 5 pages, 4 figure

    Precision characterisation of two-qubit Hamiltonians via entanglement mapping

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    We show that the general Heisenberg Hamiltonian with non-uniform couplings can be characterised by mapping the entanglement it generates as a function of time. Identification of the Hamiltonian in this way is possible as the coefficients of each operator control the oscillation frequencies of the entanglement function. The number of measurements required to achieve a given precision in the Hamiltonian parameters is determined and an efficient measurement strategy designed. We derive the relationship between the number of measurements, the resulting precision and the ultimate discrete error probability generated by a systematic mis-characterisation, when implementing two-qubit gates for quantum computing.Comment: 6 Pages, 3 figure
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