Mary Ann Horn | Photo courtesy of the Horn family

During the COVID-19 pandemic, Mary Ann Horn used her extensive expertise in mathematics to model the spread of the offending virus among hospital and healthcare workers.

“Her studies have not only influenced the mathematical biology community, but also made an impact on the related medical community,” said Shigui Ruan, PhD, a math professor at the University of Miami, who collaborated with Horn on the research. “She will be sorely missed.” 

Horn died in February. She arrived on campus in 2017 and joined the College of Arts and Sciences’ Department of Mathematics, Applied Mathematics and Statistics as chair.

She served in that role for three years.

Widely recognized for establishing mathematical biology as a thriving sub-discipline of applied mathematics nationally, Horn was a highly respected member of the academic community. She was also known for her commitment to collaborative research, bringing clinicians and experimentalists together with mathematicians and computational scientists.

Before joining CWRU, she was a program officer in the National Science Foundation’s (NSF) Division of Mathematical Sciences for more than a dozen years, and a professor of mathematics at Vanderbilt University. At the NSF, she ran the Mathematical Biology Program, which supports research in applied and computational mathematics relevant to biological and life sciences.

“She was a driving force behind many collaborative programs at NSF,” said Lisa Fauci, PhD, who worked with Horn at NSF and is the Pendergraft Nola Lee Haynes Professor at Tulane University. “I was always impressed by the breadth and depth of her knowledge in applied mathematics, her ease in leading discussions and her overall warmth and humanity.”

Fauci also said that Horn’s “beautiful work on antibiotic-resistant bacteria developed population-level models that built upon clinical data.” This work involved mathematical modeling of the development and spread of antibiotic resistance in bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin- resistant enterococci (VRE).

Qimin Huang, PhD, who completed a postdoc in mathematics at CWRU and was a department lecturer, said Horn played an important role in her life.

“She served not just as my postdoctoral advisor, but also as a cherished friend and a profound inspiration,” said Huang, now an assistant professor at the College of Wooster. “Her warmth, generosity and guidance were pivotal to my academic journey.”

Huang also vividly recalls when Horn invited her to join her at a workshop for women in mathematical biology, where Horn was speaking.

“Hearing her narrative about how at the start of the pandemic she became a pioneering female mathematician in her department lit a beacon of hope within me, marking an extraordinary beginning to my research career,” Huang said.

Horn also was active in various activities to support the CWRU community. She served on several College of Arts and Sciences’ committees, as well as the Case School of Engineering’s search committee for a chair of Computer and Data Sciences.

In addition, Horn played a role in several prestigious organizations, including the American Mathematical Society, the Mathematical Association of America and the Association for Women in Mathematics. She also served on the board of the Society for Industrial and Applied Mathematics.

“Mary Ann will be deeply missed,” said Weihong Guo, PhD, the chair of the Department of Mathematics, Applied Mathematics and Statistics.