Mutagenic and carcinogenic potency of extracts of diesel and related environmental emissions: Study design, sample generation, collection, and preparation

A major diesel emissions research program has been initiated by the U.S. Environmental Protection Agency to assess the human health risk associated with increased use of diesel automobiles. This program is intended to establish the mutagenic and carcinogenic potency of complex organics associated with diesel particles as well as comparative particle-bound organics from other environmental emissions for which human epidemiological data are available. The mobile source samples selected for this study were collected from a heavy-duty diesel engine, a series of light-duty diesel passenger cars, and a gasoline catalyst automobile. The comparative source samples incorporated into the study were cigarette smoke condensate, coke oven emissions, roofing tar emissions, and benzo(a)pyrene. The samples were tested using three mutagenic assays and four carcinogenic assays as prescribed by a test matrix. This report describes the study design, particle generation, and sample collection and preparation. A brief summary of the bioassays is also included.     

Spectral analysis of forest model time series

The use of spectral analysis to elucidate the cyclic behavior in time series generated by a forest stand growth simulation model is discussed. A stand-level simulator, FORET, for an Appalachian deciduous forest is described. An estimate of the power spectral density of the total biomass time series is calculated. The power spectral density estimate indicates a dominant cyclic behavior with a period of about 200 years. In addition the spectral density is approximately bandlimited. This characteristic makes possible the application of the sampling theorem for analysis of sampling rates.     

Sensory influence upon grasshopper stridulation

The Science of Nature -