Copepoda and Cladocera Populations of Red Rock Reservoir, Iowa from April to November, 1970

The effects of nutrient renewal, conservation pool water level, and the average weekly discharge rate on the species composition, relative abundance, and population fluctuations of the Copepoda and Cladocera of Red Rock Reservoir were determined. The average retention time (flushing rate) was 11.2 days. Twenty-one species were identified with the dominants being Cyclops spp., Diaptomus spp., Daphnia spp., Bosmina longirostris, Moina micrura, Ceriodaphnia quadrangula, and Diaphano-soma spp. Three distinct seasonal peaks in population growth were noted. Population fluctuations showed slight correlation with temperature, transparency, discharge rate, nutrient levels and no relationship was seen with water level. A time interval of 18 to 32 days occurred between high nitrate and phosphate levels and population abundance peaks. Species composition showed distinct seasonal changes. Population numbers began increasing at the dam area and continued upstream with declines following the reverse pattern

Racial and Ethnic Disparities in Access to Physicians with HIV-related Expertise: Findings from a Nationally Representative Study

OBJECTIVE: Professional medical associations recommend that physicians who treat patients with human immunodeficiency virus (HIV) have a measurable form of disease-specific expertise, such as high HIV patient volume or infectious diseases certification. Although it is known that racial/ethnic minorities generally have worse access to care than do whites, previous work has not examined disparities in the use of physicians with HIV-related expertise. DESIGN, SETTING, AND PARTICIPANTS: We linked data from a prospective cohort study of 2,207 persons with HIV receiving care in the United States with a cross-sectional survey of 404 physicians caring for them. Using multivariate analysis, we estimated the association of patient race/ethnicity with the experience and training of their physicians, controlling for health status, socioeconomic status, demographic characteristics, and geographic variation in provider supply. RESULTS: Compared with white patients, African Americans were less likely to have an infectious diseases specialist as a regular source of care (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.37 to 0.95). Persons of Alaskan Native, American Indian, Asian, Pacific Islander, or mixed racial background were also less likely than whites to have an infectious diseases specialist (OR, 0.44; 95% CI, 0.23 to 0.83). Conversely, Latino patients had physicians whose HIV patient volume was, on average, 24% higher than the physicians of white patients (incident rate ratio, 1.24; 95% CI, 1.03 to 1.50). CONCLUSIONS: Some groups of racial/ethnic minorities are less likely than are whites to have infectious diseases specialists as a regular source of care. The finding that the physicians of Latino patients had relatively higher HIV caseloads suggests that this particular patient subpopulation has access to HIV expertise. Further work to explain racial/ethnic differences in access to physicians will help in the design of programs and policies to eliminate them