排序方式: 共有23条查询结果,搜索用时 0 毫秒
21.
Wallerstein LF Barroso R Tricoli V Mello MT Ugrinowitsch C 《Journal of aging and physical activity》2010,18(4):390-400
Ramp isometric contractions determine peak torque (PT) and neuromuscular activation (NA), and ballistic contractions can be used to evaluate rate of torque development (RTD) and electrical mechanical delay (EMD). The purposes of this study were to assess the number of sessions required to stabilize ramp and ballistic PT and to compare PT and NA between contractions in older adults. Thirty-five older men and women (age 63.7 ± 3.7 yr, body mass 64.3 ± 10.7 kg, height 159.2 ± 6.6 cm) performed 4 sessions of unilateral ramp and ballistic isometric knee extension, 48 hr apart. PT significantly increased (main time effect p < .05) from the first to the third session, with no further improvements thereafter. There was a trend toward higher PT in ballistic than in ramp contractions. No difference between contraction types on EMG values was observed. Therefore, the authors suggest that 3 familiarization sessions be performed to correctly assess PT. In addition, PT, NA, RTD, and EMD can be assessed with ballistic contraction in older adults. 相似文献
22.
Michelle M. Mello J.D. Ph.D. M.Phil. Brian R. Clarridge Ph.D. David M. Studdert LL.B. Sc.D. M.P.H. 《Accountability in research》2013,20(3):163-191
We conducted a mail survey of 884 U.S. medical school faculty active in clinical research to elicit their views about the acceptability of provisions in contracts for industry-sponsored clinical trials that would restrict investigators’ academic freedom and control over trials. We compared their responses to results from a similar survey of research administrators at 107 medical schools. There was substantial variation among clinical researchers in their acceptability judgments, with a relatively large proportion of clinical trial investigators willing to accept provisions that give industry sponsors considerable control over the dissemination of research results. There were significant differences in the perceptions of clinical trial investigators versus other recently published clinical researchers; investigators with a high versus low percentage of research support from industry; junior versus senior faculty; and investigators at institutions with high versus low National Institute of Health (NIH) funding ranks. There was also a significant divergence of views in a number of areas between clinical trialists and research administrators who negotiate clinical trial contracts on their behalf. Medical school faculty could benefit from additional guidance about what their institution views as acceptable parameters for industry-sponsored clinical trial agreements. 相似文献
23.
Estimating the sizes of hard-to-count populations is a challenging and important problem that occurs frequently in social science, public health, and public policy. This problem is particularly pressing in HIV/AIDS research because estimates of the sizes of the most at-risk populations-illicit drug users, men who have sex with men, and sex workers-are needed for designing, evaluating, and funding programs to curb the spread of the disease. A promising new approach in this area is the network scale-up method, which uses information about the personal networks of respondents to make population size estimates. However, if the target population has low social visibility, as is likely to be the case in HIV/AIDS research, scale-up estimates will be too low. In this paper we develop a game-like activity that we call the game of contacts in order to estimate the social visibility of groups, and report results from a study of heavy drug users in Curitiba, Brazil (n = 294). The game produced estimates of social visibility that were consistent with qualitative expectations but of surprising magnitude. Further, a number of checks suggest that the data are high-quality. While motivated by the specific problem of population size estimation, our method could be used by researchers more broadly and adds to long-standing efforts to combine the richness of social network analysis with the power and scale of sample surveys. 相似文献