Sulfur dioxide and dimethyl sulfide were determined in the marine boundary layer of the northeast Pacific Ocean west of Seattle, Washington. The mean DMS and SO2 concentrations were 75 and 28 pptv, respectively. During periods of high DMS levels (180 pptv) we found that SO2 levels remained low (25 pptv) and statistically the same as periods of low DMS. Sulfur dioxide showed no observable diurnal variation indicating that nonphotochemically driven losses to aerosol and other surfaces cannot explain the low SO2 levels observed. We conclude that a low efficiency of conversion of DMS to SO2 is the most likely explanation for the low SO2 levels. Implications of the low yield of SO2 in terms of the kinetics of oxidation of DMS are discussed.

The variation of OCS in the northern hemisphere for the period 1977-1991 was investigated by grouping 'all measurements made by our research group for that period. The data set contained 1066 measurements made in the northern hemisphere over a longitude range of 52 E to 155 W and a latitude range of l0 N to 85 N. About 50% of the measurements were made from aircraft. The overall data set had a meau of 512 parts per trillion by volume (pptv) and a standard deviation of 119 pptv. The data obtained from aircraft had a mean of 514 pptv aud a standard deviation of 64 pptv. A study of the time series constructed from the data set and several subsets indicate that the change in global OCS with time is between -1.5 and 1.5 parts per trillion per year at the 95% confidence level. The data had no seasonal dependence within the precision of the data set.

Postmodern and evidence-based practice (EBP) are compared and contrasted with the primary aim of adapting evidence-based practice with a more flexible epistemological lens. We begin by reviewing the epistemological underpinnings of postmodern and EBP within the field of marriage and family therapy (MFT). We next discuss how these contrasting philosophies inform therapists' traits and practice in the context of translational research and practice-based evidence. Finally, we point toward some promising directions for a flexible adaptation of evidence-based practice in which both modern and postmodern clinicians can practice, and ways to incorporate some of these more flexible principles into the clinical training of MFT students.

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