Research Roundup: A Great Cup of Coffee Through Physics, Math Nudges, and More
We share recent findings from four Penn Arts & Sciences faculty, including one who used physics to make a delicious cup of coffee with fewer beans and another studying behavioral health practices to improve math scores.
Coffee lovers understand the desire to make a great cup without breaking the bank. Now Arnold Mathijssen, an assistant professor in the Department of Physics and Astronomy, and colleagues have figured out how to do so using a combination of fluid dynamics and particle physics. “We weren’t just doing this for fun,” Mathijssen says. “We had the tools from other projects and realized coffee could be a neat model system to explore deeper physical principles.”
To understand water flow in the pour-over coffee process, the team, which also included PhD students Ernest Park and Margot Young, used a gooseneck kettle and transparent silica gel in a glass cone, coupled with a laser sheet and high-speed camera. Later experiments replicated the process with actual coffee grounds.
Their findings—published in the journal Physics of Fluids and shared below—represent one of four recent studies from Penn Arts & Sciences faculty in this edition of Omnia’s Research Roundup.
A More Efficient Pour
To create a delicious yet less-expensive cup of coffee, Arnold Mathijssen, an assistant professor in the Department of Physics and Astronomy, and colleagues turned to physics. Their aim? To use fewer beans yet increase the flavor that comes from them, resulting in coffee that still tastes great. By replicating the pour-over process first with silica gel and then actual coffee, they determined that the height of the kettle dispensing the water and the speed at which it flows matter greatly. They also learned that using the fluid dynamics of an avalanche can affect how much flavor gets extracted from the beans.
Mathijssen says the work has implications beyond a cup of coffee, including for behaviors like rock erosion under waterfalls or the process for treating wastewater. “You can start small, like with coffee, and end up uncovering mechanisms that matter at environmental or industrial scales.”
Boosting Math Scores
Simple email nudges to teachers can improve the math skills of their young students, according to findings from Angela Duckworth, Rosa Lee and Egbert Chang Professor, and colleagues in Penn’s Behavior Change for Good initiative. The research, which involved more than 140,000 teachers and nearly 3 million elementary-age students, showed that emails referencing data specific to a teacher’s students (versus those without) boosted progress by more than 2 percent, with effects lasting eight weeks after the intervention.
“Ultimately,” Duckworth says, “this line of research could help shape smarter, more effective education policies.” The researchers published their results in Proceedings of the National Academy of Sciences.
Long-Ago Land Use
Climate models work to predict the future by relying, in part, on data from the past about how humans have modified vegetation. Given that people have affected the land for thousands of years, that information can be difficult to come by.
Now, through a project called LandCover6k, a team including Emily Hammer, Assistant Professor of Middle Eastern Languages and Civilizations, and Kathleen Morrison, Sally and Alvin V. Shoemaker Professor of Anthropology, have showed that at two important points in agricultural history—6,000 and 12,000 years ago—most land in South Asia was used by hunter-gatherers, who also fished and foraged for food. Morrison says this work, published in PLOS One, “adds to our overall understanding of the interconnected histories of humans and the environment.”
Mortality Risk
In a recent Science Advances paper, a team that included Michael Mann, Penn’s Vice Provost for Climate Science, Policy, and Action, and Presidential Distinguished Professor of Earth and Environmental Science, connected rising temperatures, temperature variability, and extreme heat with increased mortality risk for elderly people in China.
To draw this conclusion, the researchers looked at data between 2005 and 2018 for more than 27,000 people, ages 65 and up, as well as temperature and precipitation trends. “Translating fundamental scientific research into action on the ground,” Mann says, “is an important component of our emerging vision here at Penn in the realms of climate and sustainability.”
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