THE DISTRIBUTION OF AGE DISPARITIES IN CONIFER CHARCOAL FROM ARCHAEOLOGICAL STRUCTURES AND APPLICATIONS FOR TREE-RING-RADIOCARBON DATING

ABSTRACT Age disparities between charcoal samples and their context are a well-known problem in archaeological chronometry, and even small offsets could affect the accuracy of high-precision wiggle-matched dates. In many cases of taphonomic or anthropogenic loss of the outermost rings, sapwood-based methods for estimating cutting dates are not always applicable, especially with charcoal. In these instances, wiggle-matched terminus post quem (TPQ) dates are often reconciled with subjective or ad hoc approaches. This study examines the distribution of age disparities caused by ring loss and other factors in a large dendroarchaeological dataset. Probability density functions describing the random distribution of age disparities are then fit to the empirical distributions. These functions are tested on an actual wiggle-matched non-cutting date from the literature to evaluate accuracy in a single case. Simulations are then presented to demonstrate how an age offset function can be applied in OxCal outlier models to yield accurate dating in archaeological sequences with short intervals between dated episodes, even if all samples are non-cutting dates.

Race, sex and age disparities in echocardiography among Medicare beneficiaries in an integrated healthcare system

ObjectiveTo identify potential race, sex and age disparities in performance of transthoracic echocardiography (TTE) over several decades.MethodsTTE reports from five academic and community sites within a single integrated healthcare system were linked to 100% Medicare fee-for-service claims from 1 January 2005 to 31 December 2017. Multivariable Poisson regression was used to estimate adjusted rates of TTE utilisation after the index TTE according to baseline age, sex, race and comorbidities among individuals with ≥2 TTEs. Non-white race was defined as black, Asian, North American Native, Hispanic or other categories using Medicare-assigned race categories.ResultsA total of 15 870 individuals (50.1% female, mean 72.2±12.7 years) underwent a total of 63 535 TTEs (range 2–55/person) over a median (IQR) follow-up time of 4.9 (2.4–8.5) years. After the index TTE, the median TTE use was 0.72 TTEs/person/year (IQR 0.43–1.33; range 0.12–26.76). TTE use was lower in older individuals (relative risk (RR) for 10-year increase in age, 0.91, 95% CI 0.89 to 0.92, p<0.001), women (RR 0.97, 95% CI 0.95 to 0.99, p<0.001) and non-white individuals (RR 0.95, 95% CI 0.93 to 0.97, p<0.001). Black women in particular had the lowest relative use of TTE (RR 0.92, 95% CI 0.88 to 0.95, p<0.001). The only clinical conditions associated with increased TTE use after multivariable adjustment were heart failure (RR 1.04, 95% CI 1.00 to 1.08, p=0.04) and chronic obstructive pulmonary disease (RR 1.05, 95% CI 1.00 to 1.10, p=0.04).ConclusionsAmong Medicare beneficiaries with multiple TTEs in a single large healthcare system, the median TTE use after the index TTE was 0.72 TTEs/person/year, although this varied widely. Adjusted for comorbidities, female sex, non-white race and advancing age were associated with decreased TTE utilisation.