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The cochlear microphonic potential (CM) and the compound action potential (CAP) cannot be measured separately but only in combination. In the literature their individual estimates are conventionally recovered by the so-called CM cancellation technique. This method averages the potential obtained in response to rarefaction and condensation clicks under the assumption that changing the polarity of the clicks only affects the CM sign and does not alter the CAP in any way. However, both theory and evidence suggest that these hypotheses can be critical. In addition, recent contributions in the electrocochleography (ECochG) literature suggested that assessing the influence of stimulus polarity on the evoked CAP may constitute an indicator of clinical usefulness which the CM cancellation method cannot supply. In this work we propose a new algorithm to estimate the cochlear potentials evoked from positive clicks, CAP+ and CM+, and those evoked from negative clicks, CAP- and CM-, by processing the same kind and amount of data employed in the CM cancellation method. The application to real data taken from 3 subjects exhibiting quantitatively and qualitatively different ECochG responses at various levels of stimulation intensity is presented. In addition, simulated problems where the true CAP and CM are known are studied to permit a fair assessment of the proposed technique. Results suggest that the new algorithm is potentially able to point out small differences between CAP+ and CAP-. This encourages its further employment on a larger scale. 相似文献
224.
SM Booker 《Environmental health perspectives》2001,109(10):A472-A473
225.
Trials which randomize practices II: sample size 总被引:3,自引:0,他引:3
BACKGROUND: When practices are randomized in a trial and observations are
made on the patients to assess the relative effectiveness of the different
interventions, sample size calculations need to estimate the number of
practices required, not just the total number of patients. OBJECTIVE: Our
aims were to introduce the methodology for appropriate sample size
calculation and discuss the implications for power. METHOD: A worked
example from general practice is used. DISCUSSION: Designs which randomize
practices are less powerful than designs which randomize patients to
intervention groups, particularly where a large number of patients is
recruited from each practice. Studies which randomize few practices should
be avoided if possible, as the loss of power is considerable and simple
randomization may not ensure comparability of intervention groups.
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Mouhsin M. Shafi MD PhD Emiliano Santarnecchi PhD Tamara G. Fong MD PhD Richard N. Jones ScD Edward R. Marcantonio MD SM Alvaro Pascual‐Leone MD PhD Sharon K. Inouye MD MPH 《Journal of the American Geriatrics Society》2017,65(6):1114-1118
Delirium is a common problem associated with substantial morbidity and increased mortality. However, the brain dysfunction that leads some individuals to develop delirium in response to stressors is unclear. In this article, we briefly review the neurophysiologic literature characterizing the changes in brain function that occur in delirium, and in other cognitive disorders such as Alzheimer's disease. Based on this literature, we propose a conceptual model for delirium. We propose that delirium results from a breakdown of brain function in individuals with impairments in brain connectivity and brain plasticity exposed to a stressor. The validity of this conceptual model can be tested using Transcranial Magnetic Stimulation in combination with Electroencephalography, and, if accurate, could lead to the development of biomarkers for delirium risk in individual patients. This model could also be used to guide interventions to decrease the risk of cerebral dysfunction in patients preoperatively, and facilitate recovery in patients during or after an episode of delirium. 相似文献
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Bjørn Blomberg Karim P Manji Willy K Urassa Bushir S Tamim Davis SM Mwakagile Roland Jureen Viola Msangi Marit G Tellevik Mona Holberg-Petersen Stig Harthug Samwel Y Maselle Nina Langeland 《BMC infectious diseases》2007,7(1):1-14