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The Holocene-Pleistocene transition in the upland loess-mantled regions of the central Great Plains is punctuated by the Brady Soil, which separates the late-Pleistocene Peoria Loess and the Holocene Bignell Loess. Previous research on the Brady Soil at the Old Wauneta Roadcut site in Southwestern Nebraska has produced paleoenvironmental information based on well-constrained luminescence and radiocarbon ages, stable carbon isotope data, and chemical and physical data. While the research indicated high effective moisture during formation of the Brady Soil and a shift to warm-season C 4 vegetation from the cool-season C 3 -dominated vegetation of the Peoria Loess, those data do not provide any detail as to plant community composition and significant underlying climatic inferences. Assemblages of phytoliths and other biosilicates extracted from the Brady Soil provide specific information on vegetation communities and indicate shifts of plant taxa comprising these assemblages. Short-cell phytolith count data reveal a shift from dominance of Pooideae (C 3 ) grasses, with relatively large numbers of arboreal dicot spheres and a few Cyperaceae (sedge) present in a savannah or open woodland in the Bølling-Allerød, to a mixed, open Chloridoideae (C 4 ) and Pooideae (C 3 ) grassland in the early-Holocene. Stipa-type Pooideae, a cool-season grass preferring drier soil conditions, marks the onset of the Younger Dryas. Large-cell phytoliths such as long cells, bulliforms, and trichomes, provided further definition of the climate history. This comprehensive biosilicate study of the Brady Soil has provided a more detailed paleoclimatic reconstruction than that generated with bulk sediment-derived δ 13 C data, or even with short-cell phytolith data alone.

Studies have suggested that extreme weather events have differential effects by age. By leveraging electronic medical records, we aim to analyze the environmental influence of extreme heat on the health of older adults. From our healthcare system’s de-identified data warehouse, we extracted a retrospective cohort of 108,192 patients who were ≥65 years of age as of 1/1/2018 with pre-existing chronic conditions including diabetes, COPD, cardiovascular disease, or kidney disease. Extreme heat event period was defined as 5/1/2018 to 9/1/2018 (79 days with temperature ≥90o; 15 days of moderately poor/poor air quality index (AQI) [≥75] values) and the comparison period was defined as 5/1/2019 to 9/1/2019 (51 days with temperature ≥90o; 0 days with moderately poor/poor AQI values) in the Kansas City area. We randomly partitioned the study cohort into two sets and demonstrated the two patient sets were statistically similar (p>0.05) with respect to their demographic and underlying health conditions. Finally, we compared the respiratory, cardiovascular, and renal health outcomes between the 2018 and the 2019 cohorts. Most patients were Caucasians, female and had comorbid conditions. Results showed significantly higher number of all-cause emergency department visits (p=0.04) and outpatient visits (p=<.001) during the extreme heat event period in 2018. Analyses also showed significantly higher number of outpatient visits due to upper respiratory diseases (p=0.008) and acute renal failure (p=0.01) in 2018. In conclusion, extreme heat increased use of healthcare services in older adults with chronic conditions.