A recently developed continental-scale air mass-based classification is used to identify the spatial occurrences of 6 air masses (dry polar, dry temperate, dry tropical, moist polar, moist temperate, and moist tropical) in the eastern United States for summer from 1961 to 1990. This procedure, the spatial synoptic classification (SSC), is based on 'seed' day identification of synoptic events and discriminant analysis to group days together which are within the same air mass type. Thus, the evaluation of the frequency and modification of air masses across a large region is possible. Using the SSC, maps of air mass frequencies and afternoon temperatures and dew points are developed. Rates of modification are determined as each air mass traverses the region. As an example of the environmental applicability of the SSC, the impact of climate upon human mortality is analyzed at 3 climatically different locations (New Orleans, LA; Memphis, TN; and Chicago, IL). Results show how the day-to-day mortality fluctuations are sensitive to air mass type. A particular air mass which is associated with distinctly high mortality is identified for Memphis and Chicago; no such air mass is apparent for New Orleans, where the weather/mortality signal is very weak.

A significant number of patients undergo irradiation to the temporal bone for malignancies. Conflicting reports exist regarding the effects of irradiation on hearing thresholds. Although radiation-induced otitis media and osteoradionecrosis of the ossicles with resultant conductive hearing loss are well-documented, there is disagreement regarding the effect of irradiation on sensorineural hearing. Previous animal models, relying only on behavioral tests and reflex thresholds, have failed to reveal consistent threshold shifts after irradiation. However, with the advent of auditory brainstem response (ABR) testing, a reliable objective measurement of hearing in animals is available. Hearing thresholds were determined bilaterally by ABR testing in 21 albino guinea pigs. The left temporal bones of sixteen animals were then irradiated with a total dose ranging from 5750 to 7000 cGy over 7 weeks. The right ears of these animals, plus both ears of five nonirradiated guinea pigs, served as controls. Follow-up threshold ABRs were obtained immediately post-irradiation (RT), and at 6 and 12 months post-RT. Average thresholds in all groups increased over time: 60 dB in the control group; 53 dB in the control ears of the irradiated animals; and 46 dB in the irradiated ears. There were no statistically significant increases in ABR thresholds for irradiated ears vs. control ears. At the 6-month followup, hearing was actually better in the irradiated ears than the control ears and this difference between ears was significantly greater than the difference at baseline (p < 0.026). Overall, there was no evidence that irradiation produces changes in ABR thresholds.

Historical changes in tropical Pacific rainfall are analyzed using data from the newly enhanced Comprehensive Pacific Rainfall Database (PACRAIN), a daily rain-gauge database for the Pacific that contains almost 800 sites, some with records dating back to the 1800s. After a complete analysis of the database, 24 stations were selected to examine rainfall changes from 1971 to 2000 using daily data. In addition, a series of extreme event indicators, such as the percent of annual precipitation that falls on days exceeding the 99th percentile, were selected and analyzed in accordance with the World Meteorological Organization (WMO) guidelines for analysis of extreme events. Historical precipitation records in the central and southwestern tropical Pacific showed a trend towards decreasing precipitation during the period 1971 to 2000. This is consistent with previous research on changes from 1971 to 1990, as well as previous results that use data from a different set of stations. There was an increase in the characteristics of extreme precipitation events in most locations, even in those with a decrease in overall precipitation. This could have significant impacts in a hydrological sense, and illustrates the need to use extreme event variables when analyzing climatic patterns. Longer-term patterns were revealed through an analysis of monthly data from 14 stations over the period 1951 to 2004. Results suggest that the role of the Interdecadal Pacific Oscillation (IPO), especially the positive phase, could be important in explaining a significant amount of the observed changes.

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