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A Love for Numbers

Studying infectious diseases is not necessarily a deadly task. Take it from Gerardo Chowell-Puente (pictured left), a Ph.D. candidate in biometry at Cornell University in Ithaca, New York. In hopes of better managing diseases, such as influenza and mad cow (bovine spongiform encephalopathy), Chowell-Puente uses mathematical and computational models to identify and study the mechanisms involved in transmitting them. He has examined the impact of people's movements and interactions (called dynamic social networks) on the spread of Ebola, severe acute respiratory syndrome (SARS), and smallpox. (For more about these and other illnesses, see the U.S. Centers for Disease Control and Prevention's Web site.) Last year, the importance of his work, especially on SARS, helped Chowell-Puente win Mexico's prestigious National Youth Prize (academic category).

A Budding Mathematician

Chowell-Puente spent most of his life in Colima, Mexico, and fell in love with numbers at age 8. His father, Rafael Chowell, a mining engineer, often corrected his children's math problems and gave them extra homework. Chowell-Puente became increasingly captivated by math, even eagerly showing his father his schoolwork. "I was very motivated, much more than my brothers," he says. Indeed, in high school, he placed first or second in five statewide contests in science and math.

Pushing the Limit

By the time he started college at the University of Colima, Chowell-Puente wanted to be a computer scientist. He majored in computer science and telecommunications and wanted to continue his studies in graduate school. To help him get there, he targeted opportunities outside Mexico. "I did not think my school pushed me as hard as I wanted," he says. "I needed someone to raise the bar for me."

A professor at the University of Colima realized Chowell-Puente's potential and strongly recommended him to Carlos Castillo-Chavez, a professor of biomathematics at Cornell University's Mathematical and Theoretical Biology Institute (MTBI). Castillo-Chavez was more than happy to help shape Chowell-Puente's career and accepted him into MTBI's summer program in 2000. MTBI's goal is to help underrepresented minorities prepare for graduate studies; it is now located at Arizona State University.)

Chowell-Puente's motivation also prompted him to take two semesters off from the University of Colima. He became an exchange student at the British Columbia Institute of Technology in Canada and the University of Cadiz in Spain. He hoped to make connections and learn how education works elsewhere like he had at Cornell. His eagerness and hard work paid off particularly with Castillo-Chavez, who invited him to return to MTBI's summer program as an advanced student. This was good news for Chowell-Puente. He recalls, "After that summer, I had no doubt ... that I wanted to go for a Ph.D."

Chowell-Puente was accepted as an international graduate student in Cornell's Biological Statistics and Computational Biology Department and chose Castillo-Chavez as his adviser. Initially he wanted to get into the Department of Computer Science, but he now calls it "a blessing in disguise." Instead, Chowell-Puente majors in biometry and minors in computer science. He also wants to use computational tools, aside from mathematical models, to solve problems in epidemiology.

Totally Gung-Ho About Research

You can say Chowell-Puente is fired up about his work. After taking courses for a year and a half at Cornell, he became a Ph.D. candidate. Most students take 3 years to reach this plateau. Now in his third year, Chowell-Puente has been listed as first author on four technical reports, two peer-reviewed publications, and the book chapter "Worst Case Scenarios and Epidemics," released last month in Bioterrorism: Mathematical and Modeling Approaches in Homeland Security.

He has presented his research at various conferences, including the Society for the Advancement of Chicanos and Native Americans in Science, the American Mathematical Society, and two international conferences on mathematical networks. "Equaling these accomplishments would normally take most outstanding students 5 years, but for Gerardo, his productiveness seems normal," says Castillo-Chavez. "He has this drive to continuously push research in new directions, and he works all the time. Such a combination is uncommon."

To date, Chowell-Puente is best known for his research on SARS. His data demonstrated that the SARS epidemic in Toronto was indeed controllable, confirming the quarantine orders by Canada's health officials. He and his collaborators examined the growth rate of the epidemic in areas that were already highly infected (Singapore and Hong Kong). They used these rates and SARS data from Toronto to determine how fast it was spreading there. Although "there has never been an epidemic that has been stopped in history, the SARS case in Canada demonstrated that it was possible," says Castillo-Chavez. Their model showed that early diagnosis and rapid isolation reduced SARS's impact in Toronto from possibly 200,000 people to just a few hundred.

A Strong Support System

Chowell-Puente has managed financially at Cornell thanks to research and teaching assistantships, but critical to his progress has been the familial backing from his MTBI colleagues. He especially owes a lot to Castillo-Chavez. "He always keeps an eye out for each of his students," and with him, "there is no cultural barrier," says Chowell-Puente, who also credits his adviser for his improved writing and critical thinking skills. "My experience would have been different had he not been my mentor. I don't think I would have made as strong a connection ... not only because he is a Mexican scientist, but also because he is a top researcher and one of the main promoters and supporters of minority students from around the world."

Castillo-Chavez understands his role as mentor-adviser. "Sometimes there's not enough understanding that [minority] students need to feel welcome and supported in order for them to succeed. It's not so much any form of discrimination. It's the fact that people come from different cultures, and there are very few role models," he says. This is why Castillo-Chavez has worked hard in fostering a "well-committed environment" for minorities, such as forming fellowship programs, a coalition of supporting faculty, and the MTBI program.

Aside from his studies, Chowell-Puente was also concerned about his family's financial situation in Mexico. His aging father lost his job as a mining engineer and was fortunate enough to get a part-time teaching job at the University of Colima. (In Mexico, "old professionals who lose their jobs find it very hard to find another one.") Then, the small shoe store his mom opened to compensate for the job loss closed after an earthquake in Colima last fall. His older brother has been helping make ends meet, but Chowell-Puente has also taken money from his assistantship to pay for his little brother's schooling and English lessons. Chowell-Puente's adviser is proud of his effort to help his family. "It's sort of remarkable that economically they have managed to survive and Gerardo has managed to excel," says Castillo-Chavez.

Looking Ahead

Chowell-Puente's talent has taken him far, but his rather unique environment has helped him a great deal. "I think there are ... these pockets of environment that are very supportive," Castillo-Chavez explains. "We cannot underestimate students like Gerardo, as one can see from the successes of equally nurturing math programs in Rice University and the University of Iowa."

Chowell-Puente is now searching for a postdoctoral position with a mentor who is interested in his work. He feels lucky to have a mentor who shares the same culture, but he knows great mentors come in all colors and from a variety of cultural backgrounds. "Castillo-Chavez's mentors, Simon Levin of Princeton University and Fred Brauer of the University of Wisconsin, Madison, helped my adviser and found them to be the best mentors in the world," Chowell-Puente says. "Castillo-Chavez pushes me to work with the best, and I am ready."

Edna Francisco is a freelance science writer in Washington, D.C.