While some of a cell’s compartments, such as the nucleus, are held together with a membrane, others separate out of their surroundings due to the physics of unlike fluids, like oil droplets from water. Joseph studies these droplets, called biomolecular condensates, in deep, mathematical detail. Specifically, she develops computational models to study how these compartments form, searching for deep insights into these tiny structures that have been linked to neurodegenerative diseases such as ALS and Alzheimer’s.

“A lot of my work is done in collaboration with experiments, which is why Princeton is the perfect place for doing this research, because there are several experimental teams working on biomolecular condensates,” Joseph said. “We want to develop models that are quantitative, that can give us good predictions. We interested in both understanding the systems as well as engineering them.”

She said there’s a lot of evidence suggesting that these structures can become toxic inside aging cells, and that her field seeks ways to intervene in that breakdown process to treat disease. But the structures and the dynamics that govern them are extremely complex, so the math that describes those processes is, too. Her job is to strike a balance between how detailed a model is and how fast it is to run on a computer. “Ideally, you don’t want to wait a whole year for a simulation to give you an answer,” she said. How she strikes that balance depends on the specific questions she wants to answer. And developing those questions is as much an art as a science. That’s also where strong collaborations with biologists become essential.

Joseph grew up on the island nation of Dominica, in the Caribbean’s Lesser Antilles, and got interested in computational chemistry as an undergraduate at the University of the West Indies. As much as she loved chemistry, she said she was most interested in applying that knowledge to biological problems. So she went to the University of Cambridge to study protein folding, the subject of her Ph.D. work. She then joined the Collepardo lab at Cambridge to conduct postdoctoral work on biomolecular condensates, which she completed before joining Princeton.

She said she was fortunate to have had a healthy and supportive environment throughout her training, and that creating such an environment was in turn important for her as a professor and principal investigator.

“I like my mentees to be very well trained and to understand the limitations of the work that they’re doing. But I’m also extremely interested in creating a supportive space for students to learn and grow. Because the Ph.D. is really a marathon, right? And you need the stamina to take you through those years. So being able to support students through the highs and lows is very important to me.”