UNIVERSITY PARK, Pa. — Howard Weiss, professor of biology and mathematics at Penn State, passed away peacefully in his sleep on Nov. 5 at the age of 64.

Weiss worked closely with biological and medical scientists, combining experiments and mathematical models to understand the population and evolutionary dynamics of bacteria in physically structured environments, strategies to improve antibiotic therapy, transmission of respiratory viruses, and microbiome assembly and dynamics.

Colleagues and students alike remember Weiss as kind, honest, brilliant and easily approachable. He was generous with his time, engaging and supportive of his peers, passionate about teaching, and a champion of research rigor. Penn State biology graduate student Mei-Ling Liber called him “one of the nicest professors I’ve ever known … incredibly intelligent, yet extremely kind and relatable.” Most importantly, he was devoted to his family.

“Howie was a prominent contributor to his field, our college, and Penn State, through his cross-disciplinary research and his innovative pedagogy,” said Tracy Langkilde, professor of biology and Verne M. Willaman Dean of the Penn State Eberly College of Science. “As a scientist and educator, a colleague and a friend, Howie was genuine, committed, and a truly thoughtful individual who engaged and elevated those around him.”

Weiss first joined Penn State in 1990, and after serving as a professor of mathematics at Georgia Tech from 2006 to 2019 returned to Penn State as a professor of biology and mathematics. He was a member of Penn State’s Microbiome Center and Centers for Biorenewables, Infectious Disease Dynamics, and Mathematical Biology, as well as being on the faculty of the University’s Intercollege Graduate Degree Program in Ecology. Weiss was also an adjunct professor of biology (2008-2020) and global health (2012-2020) at Emory University and an elected Fellow of the American Association for the Advancement of Science (AAAS).

Weiss was the principal investigator of the Boeing-sponsored FlyHealthy research study, which explores the rates and routes of transmission of infectious diseases in an airplane cabin during flight and strategies to mitigate transmission. In this role, he collaborated with researchers at Georgia Tech, Emory University, the J. Craig Venter Institute, Delta Airlines, and the Centers for Disease Control. His work with the FlyHealthy collaboration has been featured extensively in the media, including as part of coverage around flying during the COVID-19 pandemic in 2020 and during flu outbreaks in 2013.

“Howie’s research was characterized by rare breadth, from fundamental pure mathematical topics to the applied,” said Mark Levi, professor and department head of mathematics. “He had a very active and curious mind, always was up to date on new scientific developments, and always learning new things. Howie shared his very broad expertise with many students by teaching a wide variety of courses, and in recent years he devoted significant effort to tailor the content of math courses to the needs of biology students. He had a genuine and totally selfless interest in students’ education.”

“On a personal note,” Levi added, “I knew Howie for over three decades. I will remember him fondly, and will always miss his energy, openness, warmth and enthusiasm.”

At Penn State, Weiss taught courses in ecology, virus dynamics, microbial population dynamics, linear algebra and data analysis, stochastic processes, and statistics with applications in biology and medicine. He also worked to design new math courses for life sciences majors, a new first-year math sequence, and a machine-learning course.

“Howie was adept at using mathematics to think clearly about biological problems,” said Andrew Read, Evan Pugh Professor of Biology and Entomology, Eberly Professor of Biotechnology, and director of the Penn State Huck Institutes of the Life Sciences. “What I will remember most is his passionate advocacy that mathematics and quantitative methods be embedded in all life sciences courses—a substantial impact on our curricula and our students.”

Weiss’s commitment to research and teaching were recognized on several occasions, including with an outstanding volunteer “Torchbearer” award from the DeKalb County School District in 2017, the Statistical Science Award in the applied category from the U.S. Centers for Disease Control and Agency for Toxic Substances and Disease Registry in 2014, and by being named a Georgia Power Professor of Excellence by Georgia Tech in 2012. He published more than 50 scientific articles in peer-reviewed journals as well as a book titled “A Mathematical Introduction to Population Dynamics.”

“Howie was a tireless advocate for improving the quantitative skills of our biology students,” said Beth McGraw, professor and department head of biology. “He will be deeply missed in this sphere, but his suggestions and advice will live on in our teaching program.”

In addition to faculty positions at Penn State, Georgia Tech, and Emory University, Weiss previously served as a visiting professor at the University of Maryland. He completed his postdoctoral research at the California Institute of Technology and earned bachelor’s and doctoral degrees from the University of Maryland.

“As a colleague, Howie was like an intellectual sparring partner: he had an incisive mind, and I left every conversation with a better understanding of the ideas I came in with, whether we agreed at the end or not,” said Matt Ferrari, professor of biology and director of the Penn State Center for Infectious Disease Dynamics. “Howie was also just a friendly, warm, welcoming guy. He was an example for us all, and he has left Penn State better for the time he spent with us.”