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The Pee Tape: How Mammals Pee So Expeditiously

Tuesday, November 10th, 2020

David Hu, head of the 2015 Ig Nobel Prize-winning urination-duration-research team, has a new animated video explaining that research:

The 2015 Ig Nobel Prize for physics was awarded to Patricia Yang, David Hu, Jonathan Pham, and Jerome Choo, for testing the biological principle that nearly all mammals empty their bladders in about 21 seconds (plus or minus 13 seconds).

They explain that research in detail, in the study “Duration of Urination Does Not Change With Body Size,” Patricia J. Yang, Jonathan Pham, Jerome Choo, and David L. Hu, Proceedings of the National Academy of Sciences, vol. 111 no. 33, August 19, 2014, pp. 11932–11937.

Patricia Yang and David Hu, together with additional colleagues, were awarded a second Ig Nobel Prize four years later. The 2019 Ig Nobel Prize for physics was awarded to Patricia Yang, Alexander Lee, Miles Chan, Alynn Martin, Ashley Edwards, Scott Carver, and David Hu, for studying how, and why, wombats make cube-shaped poo.

They explain that research in detail, in the study “How Do Wombats Make Cubed Poo?” Patricia J. Yang, Miles Chan, Scott Carver, and David L. Hu, paper presented at the 71st Annual Meeting of the APS Division of Fluid Dynamics, Abstract: E19.0000, November 18–20, 2018.

New, tail-swinging research from the urination-duration lab

Tuesday, October 23rd, 2018

Ig Nobel Prize winner David Hu and colleagues published a new study investigating why elephants and other tail-swinging mammals swing their tails. Specifically, they looked at how (and how well) tail-swinging repels insects.

The new study is: “Mammals Repel Mosquitoes With Their Tails,” Marguerite E. Matherne, Kasey Cockerill, Yiyang Zhou, Mihir Bellamkonda, David L. Hu, Journal of Experimental Biology, vol. 221,  2018, jeb178905. The researchers explain:

“The swinging of a mammal’s tail has long been thought to deter biting insects, which, in cows, can drain up to 0.3 liters of blood per day. How effective is a mammal’s tail at repelling insects? In this combined experimental and theoretical study, we filmed horses, zebras, elephants, giraffes and dogs swinging their tails. The tail swings at triple the frequency of a gravity-driven pendulum, and requires 27 times more power input. Tails can also be used like a whip to directly strike at insects. This whip-like effect requires substantial torques from the base of the tail…, comparable to the torque of a sedan, but still within the physical limits of the mammal. Based on our findings, we designed and built a mammal tail simulator to simulate the swinging of the tail. The simulator generates mild breezes…, comparable to a mosquito’s flight speed, and sufficient to deter up to 50% of mosquitoes from landing. This study may help us determine new mosquito-repelling strategies that do not depend on chemicals.”

Kathryn Knight, writing in that same journal, talks about the wonders of this tail-swinging study: “Tails guard against voracious insects with curtain of breeze.”

BACKGROUND: David Hu and other colleagues at Georgia Tech were awarded the 2015 Ig Nobel Physics Prize for testing the biological principle that nearly all mammals empty their bladders in about 21 seconds (plus or minus 13 seconds). The new tail-swinging study cites, among other studies, one that itself led to an Ig Nobel Physics Prize (in 2016):

Horváth, G., Blahó, M., Kriska, G., Hegedü s, R., Gerics, B., Farkas, R. and Åkesson, S. (2010). An unexpected advantage of whiteness in horses: the most horsefly-proof horse has a depolarizing white coat. Proc. R. Soc. B 277, 1643-1650.

BOOK: David Hu has a new book called “How to walk on water and climb up walls,” which he will present on tour in the coming months.

BONUS: Another new paper from the same lab, but the other end of the elephant: “Elephant trunks form joints to squeeze together small objects,” by Jianing Wu, Yichao Zhao, Yunshu Zhang, David Shumate, Stephanie Braccini Slade, Scott V. Franklin, and David L. Hu.

A poetical, time-centric film about fluid dynamics

Friday, November 15th, 2013

Flora Lichtman produced another poetical video for Science Friday, this one about the mammal micturation duration research study that is garnering so much attention, and that will be discussed as part of a landmark session at the APS Division of Fluid Dynamics, in Pittsburgh, Pennsylvania, on Sunday, November 24, 2013:

BONUS: Listen to Science Friday‘s radio segment on the subject.

BONUS: The Science Friday program is produced in New York City. If you are or plan to be in New York City, it may be worth your time to peruse Alina Adams’s “NYC Bathrooms: How to Find Public Restrooms When You’ve Got to Go!

Mammals on Display

Monday, August 19th, 2013

Kees Moeliker, curator of the Natural History Museum Rotterdam, is visiting Washington DC. He reports:

I arrived in Washington at the end of the afternoon, and found out the National Museum of Natural History was open till 7:30 pm. So I had a full hour to wander around the exhibition halls. I especially liked the way the museum presents the (recent) mammals. The human species was definitely the best part:

hall-of-mammals-web

Killer Whales – the tax implications of

Wednesday, April 17th, 2013

As our informed readerbase will know, Killer whales (Orcinus orca ) are not fish. What then are the tax implications for ‘owners’ of killer whales – given that US tax law has specific regulations which differ considerably according to whether one owns a killer whale (a mammal), or a large fish, say a Great White shark (Carcharodon carcharias).

The position is clarified in this short video, where Professor Jeff H. Karlin, JD, LLM, from Golden Gate University, US, outlines the character of a Killer whale for tax porpoises:

Improbable Research