Marie Claire Chelini, Trinity Communications
Awarded annually since 1955, Sloan Research Fellowships are one of the most prestigious awards available to U.S. and Canadian researchers.
Chen’s research focuses on sampling algorithms – procedures that allow us to draw samples out of a distribution or population. They give us a glimpse into the unknown, whether the unknown is impossible to determine or too complex to be calculated with certainty, like weather forecasts or stock market analyses. Chen is particularly interested in a broad class of algorithms known as Markov chain Monte Carlo (MCMC).
“MCMCs are routinely used in an amazing variety of fields ranging from ecology to astrophysics to finance,” said David Dunson, Arts and Sciences Distinguished Professor of Statistical Science, and Chen’s nominator. “However, efficiency can be poor in many problems involving large datasets and/or complex models.”
Chen’s research aims to tackle this issue by improving our fundamental understanding of MCMCs and developing theoretical foundations to guide their usage in large-scale computational problems.
“This project aims to provide a theoretical framework to compare MCMC sampling algorithms and to explain clearly the computational advantages and disadvantage of widely-used but previously-mysterious algorithms such as Hamiltonian Monte Carlo,” said Chen.
In 2021, not long before joining Duke, Chen caused ripples in the statistics and computer science worlds by solving a decades-old geometry problem with vast computing applications. And he did it while trying to get a better understanding of random sampling.
“Yuansi is a rare talent who has the intellectual engine, focus and creativity to transform our understanding of the root causes of sampling efficiency/inefficiency,” said Dunson. “Also, in doing so, he has the ability to develop new mathematics, which can have a much broader impact in other areas while being of substantial intellectual merit in its own right.”
Welsher’s research also focuses on methods that shine a light on the unknown. In his case, though, it is a literal light: he develops microscopy methods that allow the visualization and measuring of never-seen-before processes happening inside and around living cells, such as viruses on the verge of attacking.
The challenges of visualizing something as small as a virus don’t stop at their microscopic size. Virus infections, and other biological processes, are dynamic. Visualizing them requires not only zooming in close enough, but also following their movement. He compares it to following a car chase through security cameras: you can get the main idea, but not any details.
To address that, Welsher developed a microscopy technique called 3D single-molecule active real-time tracking (3D-SMART), which locks onto the moving target while keeping a bird’s-eye-view of the surrounding cells.
Now, Welsher wants to take 3D-SMART to the next level. Rather than just follow a moving target, he and his team hope to control viruses and molecules using a very low electric current to essentially “trap” them. These trapped targets could then be observed and manipulated in their relevant chemical or biological environment, and not just in isolated observation chambers.
“Our group has developed high-speed 3D microscopy methods to ‘lock on’ to fast-moving single molecules and viruses in complex environments,” said Welsher. “Thanks to the Sloan Foundation, we will expand this capability to not just follow fast processes, but to be able to control nanoscale objects in complex biological and chemical environments.”
“Kevin Welsher’s research program has multiple avenues for impact,” said Katherine Franz, chair of the Chemistry department and Welsher’s nominator. “The advanced imaging methods he and his group are developing are applicable to a broad range of biophysical and material questions. The ability to probe viral infection with unparalleled precision seems certain to not only test existing hypotheses regarding the infection pathway, but to discover completely unanticipated insights into biophysical mechanisms that have important medical consequences.”
Franz also highlights Welsher’s teaching record. “Reading student comments like ‘Dr. Welsher renewed my passion for chemistry’ is a thrill. Igniting the fire for an undergraduate’s thirst for knowledge is an accolade of the highest order. It is no wonder he was awarded Duke’s Robert Cox Distinguished Teaching Award.”
More than 1,000 researchers are nominated each year for 126 Sloan Research fellowship slots. Winners receive a two-year, $75,000 fellowship.