Computer-assisted detection of microcalcifications in mammographic images will likely require a multistage algorithm that includes segmentation of possible microcalcifications, pattern recognition techniques to classify the segmented objects, a method to determine if a cluster of calcifications exists, and possibly a method to determine the probability of malignancy. This paper focuses on the first three of these stages, and especially on the classification of segmented local bright spots as either calcification or noncalcification. Seven classifiers (linear and quadratic classifiers, binary decision trees, a standard backpropagation network, 2 dynamic neural networks, and a K-nearest neighbor) are compared. In addition, a postprocessing step is performed on objects identified as calcifications by the classifiers to determine if any clusters of microcalcifications exist. A database of digitized film mammograms is used for training and testing. Detection accuracy of individual and clustered microcalcifications is compared across the seven methods using area under the ROC curve as a figure of merit.
At least one co-author has disclosed a financial relationship of potential relevance for this research. Further information is available online at http://www.nber.org/papers/w24450.ack NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.
■ Large majorities of principals described social and emotional learning (SEL) as a top priority.■ Most educators rated a wide range of SEL skills as important, although teachers tended to assign greater importance to SEL skills than principals did.
The coronavirus (COVID-19) has spread quickly across the nation with a disproportionate impact on Black Americans. Many college-aged students receive their COVID-19-related information through social media and television even though research suggests that social media sources are more likely to be incorrect. Some students report trusting these sources over government sources such as the CDC and WHO. The purpose of this study was to understand Historically Black College and University (HBCU) students’ COVID-19 knowledge, sources of information, and planned precautions. There were 21 in-depth interviews conducted with students attending a large southern HBCU during Spring 2020. Themes regarding knowledge included the following: it is a flu-like condition, it has international roots, there is inaccurate and changing information, and it is a pandemic. Themes regarding sources included: the news, US government and related officials, social media, interactions with family, and other social interactions. Themes regarding severity included the following: statistics, a distrust for hospital reporting, a belief that COVID-19 deaths were conflated with baseline health, peer influence, and familial influence. Themes regarding precautions included the following: proper mask use, hand washing/ sanitizing, avoiding large crowds/small crowds only, physical distancing, COVID-19 testing/symptom monitoring, and COVID-19 vaccination.
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