Faculty member Mary Ann Horn passes away

Photo of Mary Ann Horn

The Case Western Reserve University community is mourning the loss of Mary Ann Horn, professor in the Department of Mathematics, Applied Mathematics and Statistics. 

Widely recognized for establishing mathematical biology as a thriving subdiscipline of applied mathematics in the United States, Horn was a highly respected member of the academic community. She joined the Department of Mathematics, Applied Mathematics and Statistics in July 2017, serving as department chair from 2017 to 2020. 

Prior to joining CWRU, Horn was a program officer in the National Science Foundation’s (NSF) Division of Mathematical Sciences for over a dozen years, and a professor of mathematics at Vanderbilt University. It was while at the NSF that she ran its Mathematical Biology Program, which supports research in areas of applied and computational mathematics relevant to the biological and life sciences.

Making an impact outside of CWRU

Lisa Fauci—a math professor at Tulane University who worked with Horn at the NSF—paid tribute to Horn’s commitment to practicing and fostering collaborative research, bringing clinicians and experimentalists together with mathematicians and computational scientists. 

“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 said. 

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

Most recently, Horn applied her research expertise to modeling the spread of SARS-CoV-2 infection in populations of hospital and health care workers. Shigui Ruan, a math professor from University of Miami, collaborated with Horn on this work and reflected on her contributions.

“Her studies have not only influenced the mathematical biology community but also made an impact on the related medical community,” Ruan said. “Dr. Horn was also an active research mentor with the Association of Women in Mathematics. She will be sorely missed.”

Making a difference for future mathematicians

Qimin Huang, who completed a postdoc in mathematics at CWRU and then became a lecturer in the department, described how she benefited from Horn’s example and encouragement. 

“She served not just as my postdoctoral advisor, but also as a cherished friend and a profound inspiration,” said Huang, who is 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 becoming the pioneering female mathematician in her department lit a beacon of hope within me, marking an extraordinary beginning to my research career,” Huang said.

Outside of her research and mentorship, Horn was an active participant in various activities to support the university. At CWRU, she served on the college’s Committee for Appointments, the Budget Subcommittee, and the Strategic Planning Steering Committee, as well as Case School of Engineering’s Computer and Data Sciences Chair Search Committee.

Horn was actively involved 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. 

Lee Thompson, interim dean of the College of Arts and Sciences, was impressed with Horn the first time that she met her.

“I first met her over lunch during her initial campus visit, at a table where I was one of several women, all department chairs,” Thompson said. “I was struck not only by her past accomplishments, but also by how easily she entered into the lively, collegial conversation we were enjoying.”

She will be greatly missed by her colleagues, mentees and students.

Read Horn’s obituary.

A celebration of life will be held in Bloomsburg, Pennsylvania and will be announced at a later date. Students who would like support during this time are encouraged to contact University Health and Counseling Services at 216.368.5872. This line is staffed by a counselor 24 hours a day, seven days a week. Faculty and staff can access counseling at any time by calling IMPACT Solutions at 1.800.227.6007.