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Biomedical subjects

David J Thomson

Publications and source records attributed to David J Thomson.

2 recordsLinked to original sources

Multitaper scan-free spectrum estimation using a rotational shear interferometer.

Multitaper methods for a scan-free spectrum estimation that uses a rotational shear interferometer are investigated. Before source spectra can be estimated the sources must be detected. A source detection algorithm based upon the multitaper F-test is proposed. The algorithm is simulated, with additive, white Gaussian detector noise. A source with a signal-to-noise ratio (SNR) of 0.71 is detected 2.9 degrees from a source with a SNR of 70.1, with a significance level of 10(-4), approximately 4 orders of magnitude more significant than the source detection obtained with a standard detection algorithm. Interpolation and the use of prewhitening filters are investigated in the context of rotational shear interferometer (RSI) source spectra estimation. Finally, a multitaper spectrum estimator is proposed, simulated, and compared with untapered estimates. The multitaper estimate is found via simulation to distinguish a spectral feature with a SNR of 1.6 near a large spectral feature. The SNR of 1.6 spectral feature is not distinguished by the untapered spectrum estimate. The findings are consistent with the strong capability of the multitaper estimate to reduce out-of-band spectral leakage.

Journal Article↗

Incidence of influenza in Ontario following the Universal Influenza Immunization Campaign.

The purpose of this study was to determine whether the incidence of influenza in Ontario, Canada has decreased following the introduction of the Universal Influenza Immunization Campaign (UIIC) in 2000. All laboratory-confirmed influenza cases in Ontario, from January 1990 to August 2005 were analyzed using multitaper time series analysis. We found that there has not been a decrease in the mean monthly influenza rate following the introduction of the UIIC (109.5 (S.D. 20) versus 160 (S.D. 50.3) p>0.1). Despite increased vaccine distribution and financial resources towards promotion, the incidence of influenza in Ontario has not decreased following the introduction of the UIIC.

Canada↗