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Research Roundup: Blue whale heart rate, bird flights, no political bias in search results

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Each week, The Daily’s Science & Tech section produces a roundup of the most exciting and influential research happening on campus or otherwise related to Stanford. Here’s our digest for the week of Nov. 24 – Nov. 30.

First recording of blue whale heart rate

The first recording ever of a blue whale’s heart rate was developed by Stanford and Scripps Institution of Oceanography researchers, according to a study publishing the findings on Nov. 25 in “Proceedings of the National Academy of Sciences.” The team measured the whale’s heart rate using a sensor attached to the animal’s left flipper with four suction cups. 

“We had no idea that this would work and we were skeptical even when we saw the initial data,” Jeremy Goldbogen, biology assistant professor, told Stanford News. “With a very keen eye, Paul Ponganis – our collaborator from the Scripps Institution of Oceanography – found the first heart beats in the data. There were a lot of high fives and victory laps around the lab.”

The findings suggested that blue whales’ hearts are already working at maximum capacity, which explains the reason the marine creatures have not evolved to become bigger in size. 

The heart rate changes dramatically depending on the animal’s activity. When the blue whale descended, the heart rate slowed to an average of four to eight beats per minute. But at the surface, when the whale was breathing to restore its oxygen supply, its heart rate was at its highest, 25 to 37 beats per minute.

For further studies, the researchers hope to use more sensors, including an accelerometer, to understand how heart rate fluctuates during different activities. They also plan to sensor tag other marine animals too, such as fin whales, humpbacks and minke whales. 

Bird flights change understanding about lift and drag

By observing birds during takeoff and landing, Stanford researchers have suggested that current models of how lift and drag function in flight may need to be revised, found a study published on Nov. 25 in “Nature Communications.”

“The things you learn in class are not always true,” mechanical engineering assistant professor David Lentink told Stanford News. “We must revise our idea of the function of drag.”

The researchers found that birds use drag to support their body weight when taking off, and use lift to brake when landing. This opposes the conventional understanding of drag and lift forces: Drag slows an object down, whereas lift counters gravity to produce upward flight. 

Given their findings, the researchers suggested that the teachings of aerodynamics and the evolution of bird flight should be revisited and discussed in the classroom.

“None of the aerospace literature came up with using drag to support weight,” Lentink told Stanford News, while pointing to a textbook diagram of a bird flying overlayed with the forces. “That standard drawing has to be revised.”

No political bias in Google search results

There seems to be no political bias for or against the major U.S. political parties in Google search results, according to a study published by Stanford researchers this month in “Proceedings of the Association for Computing Machinery on Human-Computer Interaction.”

“Our data suggest that Google’s search algorithm is not biased along political lines, but instead emphasizes authoritative sources,” communications professor Jeff Hancock told Stanford News. “I think audits of large-scale algorithms that play such an important role in so many aspects of our lives are crucial. We need to be able to trust that these AI systems aren’t biased in important ways, and without audits, it’s difficult to assess these opaque algorithms.”

The researchers reviewed the first page of Google search results for each candidate who ran for federal office in the 2018 U.S. elections. They analyzed roughly 4 million URLs from the search engine, and found that there was no systematic exclusion of sources from ends of the political spectrum. Generally, the researchers found that sources had a centrist perspective.

“This is good news from a trust point of view, but more audits along more dimensions are needed,” Hancock told Stanford News.

Contact Derek Chen at derekc8 ‘at’ stanford.edu.