Head-Shaking Research — Ejecting Water From the Ear Canals

September 19th, 2017

Ejecting water from a person’s ear canals is potentially thrilling, for fluid dynamicists and perhaps for the person. New research on the how and why will be presented at a meeting in November:

Acceleration induced water removal from ear canals,” Hosung Kang, Katelee Averett, and Sunghwan Jung, paper (Abstract D5.00007) to be presented at the 70th Annual Meeting of the APS Division of Fluid Dynamics, November 19–21, 2017; Denver, Colorado. The researchers, at Virginia Tech, report:

“Children and adults commonly experience having water trapped in the ear canals after swimming. To remove the water, individuals will shake their head sideways. Since a child’s ear canal has a smaller diameter, it requires more acceleration of the head to remove the trapped water.

In this study, we theoretically and experimentally investigated the acceleration required to break the surface meniscus of the water in artificial ear canals and hydrophobic-coated glass tubes. In experiments, ear canal models were 3D-printed from a CT-scanned human head. Also, glass tubes were coated with silane to match the hydrophobicity in ear canals. Then, using a linear stage, we measured the acceleration values required to forcefully eject the water from the artificial ear canals and glass tubes.”

The lab has also done research on how dogs drink, how cats drink, how diving birds enter the water, how raindrops hit tree leaves, what happens when wet hands clap, and other not-at-all-simple simple-seeming questions.

(Thanks to Nicole Sharp for bringing this to our attention.)

The aerodynamics of cheetahs’ tails (recent study)

September 18th, 2017

“During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood.”

Prompting, perhaps, the question ‘what is a cheetah’s tail actually for?’

A joint US / South African study (2016) has made made steps towards answers. A set of experiments, in which tails were aerodynamically tested at various airspeeds and inclinations, in a wind tunnel, yielded results :

“[…] our first order, quasi-steady state results clearly support the hypothesis that aerodynamic effects of the cheetah’s long, furry tail contribute to the angular impulse that can be applied to the body, especially at higher speeds. Both inertial and aerodynamic effects must therefore be considered in modelling the use of the cheetah tail for manoeuvring tasks. Our results further support the observations that the cheetah tail can be used as a ‘rudder’ to contribute to fast change of heading, and as a ‘stabiliser’ during rapid acceleration and turning.”

See: Quasi-steady state aerodynamics of the cheetah tail in Biology Open (2016) 5, 1072-1076


● The image shows the morphometric tail rig used to measure aerodynamic coefficient at varying angles of inclination and airspeed.

● The authors thank the Ann van Dyk Cheetah Centre for providing the tails.

● The authors inform that the use of the cheetah tails complied with the University of Cape Town Science Faculty Ethics policy.

Saturday — The Ig Informal Lectures, at MIT

September 15th, 2017

The Ig Informal Lectures
Saturday, Sept 16, 2017, 1:00 pm
MIT, building 10, room 250 — 77 Massachusetts Avenue, Cambridge, Massachusetts, USA, Planet Earth.

You are invited. It’s free, no tickets needed. Come early to assure a seat.

A half-afternoon of improbably funny, informative, informal, brief public lectures and demonstrations:

UPDATE: Here’s video of the 2017 Ig Informal Lectures:

BONUS: This video shows TV news anchors’ first reaction, right after the 2016 Ig Nobel Prize ceremony, to seeing Thomas Thwaites in action:

BONUS: Here’s a look at one of the previous year’s lectures — this will give you some of the flavor of this annual event. The 2016 Ig Nobel Peace Prize was awarded to Gordon PennycookJames Allan CheyneNathaniel BarrDerek Koehler, and Jonathan Fugelsang for their scholarly study called “On the Reception and Detection of Pseudo-Profound Bullshit.” (That study was published in the journal Judgment and Decision Making, vol. 10, no. 6, November 2015, pp. 549–563.)

The Ig informal Lectures are a free event, organized in cooperation with the MIT Press Bookstore.

Watch the 27th First Annual Ig Nobel Prize Ceremony live!

September 14th, 2017

UPDATE: Ten new Ig Nobel Prize winners were introduced at the 27th First Annual Ig Nobel Prize Ceremony, at Sanders Theater, Harvard University. This year’s theme was “UNCERTAINTY”.

You can read some of the early press accounts.

The ceremony was webcast. Here’s recorded video:

Exploring the Confusion Matrix for Auto Bidet Seat Icons (study)

September 13th, 2017

When it comes to designing icons for the operation of household equipment, care must be taken to avoid misunderstandings.

“If the right button is pushed, the desired function will be performed. If the wrong button is pushed, an unexpected function will be performed. It might cause the user’s body or mental state of unwell even dangerous.“

This applies, for example, to the Auto Bidet Seat.

“Regarding functions, in addition to the basic jet water washes and warm seat, some medium class products still have other derivative features such as Deodorizer, Warm Air Dry and Remote Control. Some high class products even have broadcast music attempting to give users a more relax atmosphere in the toilet environment.”

To determine how readily (or otherwise) icons are understood, researchers Cherng-Yee Leung, Chih-Sheng Chang, and Da-Teh Wu, devised a set of experiments based on confusion matrices [as shown above]. They found that recognition-rates varied dramatically in percentage terms  – from an impressive 100% in some cases, like this one :

whilst some scored in mid-range :

and others only achieved a disappointing 0%

“In the age of global village, icons have to be good media of communication because the culture, language and words of some areas are different from others. With the increases of contents and complexity of new products, it is not easy to design ideal icons for users to recognize the delicate functions. Though Auto Bidet Seat has already presented for decades on the market, many function icons, even the icons with text hint, still puzzle users.”