When Ramon Castellanos, a biomedical engineering major at Florida International University, opted to make the most of the summer between his junior and senior years by applying for a National Science Foundation "Research Experience for Undergraduates" program, he had no idea he had made a life-changing decision. But after 10 weeks as a student in the program in Multi-Scale Systems Bioengineering at the University of Virginia, the outlines of this change were clear. Castellanos had been introduced to agent-based modeling, a powerful computational technique used to model complex systems. He began thinking that a career in research might be more satisfying than one in medicine; and he gained insight into the type of graduate school he might like to attend. The upshot: Castellanos arrived in Charlottesville in August 2019 as a doctoral student in biomedical engineering, where he will use agent-based modeling to model microcirculation. He will work in the lab of Shayn Peirce-Cottler, professor of biomedical engineering and the department's graduate program director. “I am really excited by the direction I am pursuing,†Castellanos said. “The UVA program played an important role in where I am now.â€