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21.
Introduction
Although ependymoma is the third most common pediatric brain tumor, we know little about the genetic/epigenetic basis of its initiation, maintenance, or progression. This is due in part to the heterogeneity of the disease, as well as the small sample size of the cohorts analyzed in most studies. 相似文献22.
The Institute of Medicine distinguishes between programs based on who is targeted: the entire population (universal), those
at risk (selective), or persons exhibiting the early stages of use or related problem behavior (indicated). Evaluations suggest
that although universal programs can be effective in reducing and preventing substance use, selective and indicated programs
are both more effective and have greater cost-benefit ratios. This paper tests these assumptions by comparing the impact of
these program types in reducing and preventing substance use at the individual level (i.e., those exposed to intervention
services) and in the population (i.e., those exposed and not exposed to intervention services). A meta-analysis was performed
on 43 studies of 25 programs to examine program comparability across IOM categories. When examining unadjusted effect sizes
at the individual level, universal programs were modestly more successful in reducing tobacco use, but selective and indicated
programs were modestly more successful in reducing alcohol and marijuana use. When adjusted to the population level, the average
effect sizes for selective and indicated programs were reduced by approximately half. At the population level, universal programs
were more successful in reducing tobacco and marijuana use and selective and indicated programs were more successful in reducing
alcohol use. Editors’ Strategic Implications: The authors’ focus on the public health value of a prevention strategy is compelling and provides a model for analyses of
other strategies and content areas. 相似文献
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Scalp electrical recording during paralysis: quantitative evidence that EEG frequencies above 20 Hz are contaminated by EMG. 总被引:2,自引:0,他引:2
Emma M Whitham Kenneth J Pope Sean P Fitzgibbon Trent Lewis C Richard Clark Stephen Loveless Marita Broberg Angus Wallace Dylan DeLosAngeles Peter Lillie Andrew Hardy Rik Fronsko Alyson Pulbrook John O Willoughby 《Clinical neurophysiology》2007,118(8):1877-1888
OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation. 相似文献
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