Viral Hepatitis in the Air Force

The reported incidence of viral hepatitis in the Air Force has increased over the past 10 years. The total number of days lost from duty has declined as has the average number of days lost per case. Distribution of USAF reported cases has been roughly equally divided among the three diagnostic categories, in contrast to the total United States reported distribution. Relatively few USAF cases have had a documented history of drug abuse since we began collecting this information, and the proportion of these cases has steadily declined. Finally, these diseases still represent significant economic and operational costs to the Air Force so that prevention and control remain important items of concern to commanders and the medical service.     

Vegetation Monitoring of Created Dune Swale Wetlands, Vandenberg Air Force Base, California

A monitoring program was established on San Antonio Terrace at Vandenberg Air Force Base to compare vegetation development at two created wetland sites and six nearby natural wetlands. The reference wetlands were chosen to represent a range of habitats in dune swale wetlands on the Terrace. Vegetation in the reference wetland plant communities varies from low-growing herbaceous marsh species with open canopies to closed canopies dominated by shrub or tree species. Transects and plots for long-term vegetation monitoring were established in all the wetlands, stratified by plant communities in the reference wetlands and by geomorphic location in the newly created wetlands. Quantitative vegetation and environmental data were collected at all the sites; measures included species distributions, species cover, and topographical elevations. Over the first three years of monitoring, variations in groundwater depth at different geomorphic locations in the created wetlands resulted in a variety of physical conditions for plant growth. In the first year, more than 100 plant species were observed, the majority being natives. During the next two years, species richness at the created wetland sites remained relatively stable and was higher than at the reference sites. Statistical comparisons of vegetation parameters by analysis of variance and hierarchical clustering exhibited patterns of increasing similarity between the created and reference wetlands. Long-term monitoring will be continued to track the progress of vegetation at the created sites, and to assess their development relative to the reference wetlands.     

SEQUENCE Visualization of Natural Attenuation Trends at Hill Air Force Base, Utah

For monitored natural attenuation to be considered as an acceptable remedial approach, the proponent must clearly document converging lines of evidence that illustrate the effectiveness of this measure. SEQUENCE, a visualization tool based on a modified radial diagram approach, is ideally suited for evaluating spatial and temporal trends that provide supporting evidence for the efficacy of monitored natural attenuation. SEQUENCE was applied to evaluate the natural attenuation of benzene, toluene, ethylbenzene, and total xylene (BTEX) concentrations observed in groundwater at Hill Air Force Base, Utah. SEQUENCE-BTEX maps provided an efficient means of documenting the declining BTEX concentrations downgradient from the source area. SE-QUENCE-Redox maps were used to facilitate a correlation between elevated BTEX concentrations; decreasing electron acceptor concentrations (oxygen, nitrate, and sulfate); and elevated metabolic byproduct concentrations (iron(II) and methane) providing a second line of evidence that suggests BTEX compounds are being destroyed through biodegradation processes downgradient from the source area. Site-specific guidelines for interpolating representative data sets for use with the SEQUENCE approach are discussed.     

Effect of the Canadian Air Force training programme on a submaximal exercise test.

Validation of the submaximal heart rate/oxygen consumption relationship as an index of 'cardiorespiratory fitness' requires the demonstration of systematic alterations in this relationship concomitant with interventions designed to alter physical fitness. To fulfil those criteria a longitudinal training/de-training study was undertaken. Previously sedentary adult subjects undertook the Canadian Airforce 5BX-XBX exercise programme. Submaximal exercise tests were performed before and after training, and following several weeks cessation of training. A regression line of submaximal heart rate on submaximal oxygen consumption was calculated from the data of each submaximal exercise test. Alterations in the regression lines were examined for each subject individually by testing statistically for difference in slope and elevation between any pair of lines. Subjects who undertook the training/de-training study demonstrated significant systematic alterations in the elevation of the regression lines concomitant with periods of training and de-training. The reproducibility of the submaximal heart rate/oxygen consumption relationship was examined in two additional groups of subjects. Group A repeated a submaximal test on 3 or 4 successive days; Group B were tested before and after 16 weeks of normal activity. Subjects in Group A demonstrated non significant, random alterations in the regression lines on repeated testing and subjects in Group B demonstrated random, though on occasion significant, alterations in the regression lines. The elevation of the submaximal heart rate/oxygen consumption relationship is therefore a valid index for detecting sequential changes in 'cardiorespiratory fitness' in individual subjects.