An investigation of time efficiency in wavelet-based Markov parameter extraction methods

This paper investigates the time efficiency of using a wavelet transform-based method to extract the impulse response characteristics of a structural dynamic system. Traditional time domain procedures utilize the measured disturbances and response histories of a system to develop a set of auto and cross correlation functions. Through deconvolution of these functions, or matrix inversion, the Markov parameters of the system may be found. By transforming these functions into a wavelet basis, the size of the problem to be solved can be reduced as well as the computation time decreased. Fourier transforms are also used in this capacity as they may increase the time efficiency even more, but at the cost of accuracy. This paper will therefore compare the time requirements associated with a time, wavelet, and Fourier-based method of Markov parameter extraction, as well as their relative accuracy in modeling the system

Insulation, Asbestos, Smoking Habits, and Lung Cancer Cell Types

The association between occupational exposure to asbestos and histological type of lung cancer was analyzed in a multicenter hospital-based case-control study (2,871 male cases and 5,240 male controls) conducted from 1981-1991. Twenty-two percent of cases and 18% of controls were employed in asbestos-related occupations for at least 1 year. Most of these asbestos jobs were in the construction field. The odds ratio (OR) among current smokers was 1.0 [95% confidence intervals (CI) 0.9 to 1.3]; for ex-smokers, the OR was 1.4 (95% CI 1.1 to 1.6). In contrast, 10% of cases and 5% of controls self-reported that they were chronically exposed to asbestos for at least 1 year. Self-reported asbestos exposure was significantly related to all lung cancer cell types among smokers and ex-smokers, although a trend in the ORs with duration of self-reported exposure was not found for current smokers. Among 48 cases and 52 controls reporting distinct exposure to building insulation, the OR was 2.2 (95% CI 1.2 to 4.3) for current smokers, and 1.8 (95% CI 0.9 to 3.6) for ex-smokers, compared to subjects who were not exposed to building insulation and asbestos. A nonsignificant association with self-reported exposure to asbestos was observed for a small number of never smokers (eight of 83 nonsmoking cases, OR = 2.0, 95% CI 0.9 to 4.6). When examining these results and their causal implications, possible misclassification and reporting biases need to be considered