RESUMO
A complete workflow was presented for estimating the concentration of microorganisms in biological samples by automatically counting spots that represent viral plaque forming units (PFU) bacterial colony forming units (CFU), or spot forming units (SFU) in images, and modeling the counts. The workflow was designed for processing images from dilution series but can also be applied to stand-alone images. The accuracy of the methods was greatly improved by adding a newly developed bias correction method. When the spots in images are densely populated, the probability of spot overlapping increases, leading to systematic undercounting. In this paper, this undercount issue was addressed in an empirical way. The proposed empirical bias correction method utilized synthetic images with known spot sizes and counts as a training set, enabling the development of an effective bias correction function using a thin-plate spline model. Its application focused on the bias correction for the automated spot counting algorithm LoST proposed by Lin et al. Simulation results demonstrated that the empirical bias correction significantly improved spot counts, reducing bias for both fixed and random spot sizes and counts.
RESUMO
Background In 1998, President Clinton launched a federal initiative to eliminate racial and ethnic health disparities. The impact on the outcomes of ST-segment-elevation myocardial infarction has not been well studied. Methods and Results ST-segment-elevation myocardial infarction outcomes from 1994 to 2015 were studied in 7942 Black, 27 665 Hispanic, and 88 727 White patients with first admission of ST-segment-elevation myocardial infarction using the Myocardial Infarction Data Acquisition System. Logistic regressions were used to assess mortality adjusting for demographics, comorbidities, and interventional procedures. There was an overall rise from 1994 to 2015 in the use of percutaneous coronary interventions in all 3 groups. Before 1998, White patients received more percutaneous coronary interventions compared with Black and Hispanic patients (P<0.05). After 1998, the disparity in use of percutaneous coronary interventions in Black and Hispanic patients was greatly reduced compared with White patients, and the difference reversed in favor of Hispanic patients after 2005 (P<0.05). There was an overall downward trend of in-hospital mortality without evidence of disparity among Black, Hispanic, and White patients. A linear regression model was used with a change point in 1998. Before 1998, the slope of 1-year all-cause and cardiovascular mortality was not statistically significant. After 1998, the mortality showed negative slopes for all 3 groups, however, with lower overall crude mortality for Hispanic patients compared with Black and White patients (P<0.0001). Conclusions The initiative launched in 1998 may have contributed to a reduction in percutaneous coronary intervention usage disparity in patients with ST-segment-elevation myocardial infarction. Short- and long-term mortality decreased in all 3 groups, but more in the Hispanic population.