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Tamara Lefcourt Ruby holds a Ph.D. in mathematics from the University of Pennsylvania, and is a research associate at Tel Aviv University. She also teaches calculus to students enrolled in The Johns Hopkins University Center for Talented Youth, and taught calculus at Harvard University and the University of Texas for fifteen years. James Sellers is Director of Undergraduate Mathematics at Pennsylvania State University, where he teaches Calculus and other math courses. Lisa Korf is an Assistant...See more