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Rachel Sousa stands before a vast body of water at the base of tall, sweeping mountains in Ireland.

Mathematics graduate thrives with simple philosophy: ‘Why not?’

By Elana Roldan

In the intricate languages of mathematics and biology, alumna Rachel Sousa, ‘20, is multilingual.

Instead of translating words, she transforms data. Instead of immersion in a foreign country, she interns at eminent research facilities. Calling her field the Rosetta Stone of mathematics and biology isn’t much of a stretch.

“Collaboration is key in progressing research forward,” she says. “It’s hard for mathematicians to just think about the math and not have any access to data, whereas the experimentalists can do all of these experiments, but some of them are very time-consuming or impossible. If you can bring the two worlds together, they synergize very well.”

The path Sousa took from Oregon State to being a Ph.D. candidate at the University of California, Irvine was paved with risk. With many of the opportunities that came her way, the chance of rejection seemed too large to overcome. But by putting herself out there, she has gone on to attend prestigious international events and earn highly competitive internships before setting foot outside academia.

Bolstered by her undergraduate experiences in the College of Science, she has reached higher and higher ever since.

Finding the best fit

While she always had mathematics at the forefront, Sousa wasn’t introduced to its application in biology until beginning at Oregon State. A panel with upper-division students during an introductory course for mathematics majors was the first time she’d seen the fields merge. Instantly, she became hooked. The final push she needed came from her advisor as she discussed changing to the mathematical biology option. He excitedly showed her his own research which integrated the disciplines, and she made the switch that same day.

“The College of Science was really good at bringing people of different backgrounds together so that you could hear different experiences and life journeys, whether they were similar to yours or not,” she said, which helped her discover her new passion.

Sousa holds up a certificate for the American Association of Immunologists Young Investigator Award while standing in front of her research poster.

Sousa wins the American Association of Immunologists Young Investigator Award for her poster presentation at the 2023 UC Irvine Immunology Symposium.

Sousa didn’t slow down from there. She soon met Associate Professor Cory Simon at a student-faculty mixer hosted by the College of Science. His work, which used mathematical modeling to predict specific grass formations in Africa and Australia, fascinated her, and she joined his lab soon after.

Two years later, she received an email from the College about an internship opportunity with the National Cancer Institute. It seemed like a stretch that she would get it, but with a few years of research under her belt and a solid support system encouraging her to try, she sent in her application and hoped for the best. What she hadn’t expected was for them to say yes.

Sousa spent the summer at the University of Utah using mathematical modeling to study breast cancer, loving every minute of it.

“That was the key moment I decided that I really enjoyed this type of work and that I wanted to pursue it moving forward,” she said.

The right mindset

After graduating from Oregon State in 2020, Sousa went to UCI to work toward her Ph.D. in Mathematical, Computational and Systems Biology. More than her GPA, she credits her acceptance into the program to her undergraduate experience at OSU.

“Doing research during undergrad was a huge part of it. Showing I had the interest and the skills to do research really helped,” she said. “Good or good enough grades, doing some sort of research in undergrad, and getting an internship will help to boost your skills.”

The inherent collaboration in mathematical biology led her to join two labs at UCI, one led by a mathematician and the other by an immunologist. She works with both to create models of the immune system and its interactions with cancer, which they ultimately want to use to predict the most effective therapy choices in eliminating the disease. Much of what she learned at Oregon State applies to what she now does daily as a professional researcher. From building models to working with ordinary differential equations, the foundations she laid as an OSU student continue to support her current work.

While studying at UCI, Sousa has not rested on her laurels. In her second year, she applied for the notoriously competitive National Science Foundation Graduate Research Fellowship Program and earned the impressive award. She also put her skills to the test in an industry setting during an internship with pharmaceutical company Pfizer, where she built models for anti-cancer small-molecule drug development.

Sousa smiles in front of a crystal clear lake bordered by craggy mountainsides and pines.

Sousa hikes to Diamond Lake during her internship with Pfizer in Colorado.

One of her proudest achievements was being selected to attend the 72nd Lindau Nobel Laureate Meeting. The meetings are annual forums that bring together Nobel Laureates and 600 emerging young scientists from around the world in Lindau, Germany. It left a lasting impression on Sousa and was another reminder to pursue any opportunity that came her way.

“I applied to attend and again was sort of like, ‘It seems like a big opportunity, I don’t know if I’ll be selected but the worst they could tell me is no.’ Except they told me yes,” she said.

“That’s such a good mindset to have in life. If you don’t try, you’re not going to get it. If the worst-case scenario is somebody telling you ‘no,’ then why not at least try? That’s sort of what’s gotten me where I am today.”

In the years since Sousa began pursuing mathematical biology at OSU, she has developed a philosophy toward her work and career. Whether applying for her undergraduate internship at the National Cancer Institute, her fellowship from the National Science Foundation or a spot at the Lindau Nobel Laureate Meeting, there was always an initial doubt about if she should even take the chance. What has become clear to her after all of these experiences is that without trying to seize an opportunity, the possibility of getting it becomes zero.

“I see all of these opportunities and they all seem like such prestigious things that I feel not good enough for, but then I apply and I get them. So I am good enough,” she said. “That's such a good mindset to have in life. If you don’t try, you’re not going to get it. If the worst-case scenario is somebody telling you ‘no,’ then why not at least try? That’s sort of what’s gotten me where I am today.”

Sousa points to the sign for the Nobel Laureate Meeting.

Sousa attends the 72nd Lindau Nobel Laureate Meeting.