Archive for 'Research News'

Towards a robotic jumping flea (new study)

Thursday, July 27th, 2017

A South Korean research team, Gwang-Pil Jung and Kyu-Jin Cho, (School of Mechanical and Aerospace Engineering/Institute of Advanced Machines and Design, Seoul National University) and Hong-Cheol Choi (Department of Physics and Chemistry, Korea Military Academy, Seoul) have made progress towards the development of jumping flea robot.

“Inspired by the relationship between leg compliance and jumping performance in the false stick insect, this paper describes how variations in leg compliance and jumping direction affect the performance of a flea-inspired jumping mechanism.”

“Our flea-inspired jumping mechanism […] performs take-off with bent legs […] The legs maximally bend in the acceleration phase, and when take-off happens, the legs remain bent. After take-off, bending and unbending of the jumping legs repeats for a while, then reduces gradually owing to damping of the legs.”

The paper doesn’t specify how high the microbot can jump, but the extensors have a spring coefficient of 280 N/m.

See: The Effect of Leg Compliance in Multi-Directional Jumping of a Flea-Inspired Mechanism, which is awaiting print publication in Bioinspiration & Biomimetics, April 2017.

Note: The research was funded by the Defense Acquisition Program Administration under the grant number UD130070ID.

The Effect of Sex on Heart Rate Variability at High Altitude [research study]

Tuesday, July 25th, 2017

The word “sex” can to refer to gender, rather than sexual activity. Perhaps disappointingly, that seems to be the case in this medical study:

The Effect of Sex on Heart Rate Variability at High Altitude,” Christopher John Boos [pictured here], Emma Vincent, Adrian Mellor, John O’Hara, Caroline Newman, Richard Cruttenden, Phylip Scott, Mark Cooke, Jamie Matu, and David Richard Woods, Medicine and Science in Sports and Exercise, epub July 20, 2017.

The authors, at Poole Hospital NHS Foundation trust, Poole; Bournemouth University, Bournemouth; Leeds Beckett University; Defence Medical Services, Lichfield; James Cook University Hospital, Middlesbrough; Wansbeck General and Royal Victoria Infirmary, Newcastle; and University of Newcastle; all in the UK, report (we added the bolding emphasis):

There is evidence to suggest that high altitude (HA) exposure leads to a fall in heart rate variability (HRV) that is linked to the development of acute mountain sickness (AMS). The effects of sex on changes in HRV at HA and its relationship to AMS are unknown.

METHODS: HRV (5-minute single lead ECG) was measured in 63 healthy adults (41 men and 22 women) aged 18-56 years at sea level (SL) and during a HA trek at 3619m, 4600m and 5140m respectively. The main effects of altitude (SL, 3619, 4600 and 5140m) and sex (men vs women) and their potential interaction were assessed…

This particular paper is distinguished by the advanced quality of the writing. The wording at the end of the paper’s abstract is so very concise that it approaches being poetry:

Conclusions: Increasing HA leads to a reduction in HRV. Significant differences between men and women emerge at HA. HRV was not predictive of AMS.

(Thanks to Adrian Smith for bringing this to our attention.)

Bike riding with up/down and left/right swaps

Tuesday, July 25th, 2017

These two videos show two related experiments that demonstrate some very weird things the human brain can do. The first, newer video shows Destin (the creator of the SmarterEveryDay videos) learning to ride a bike in which the left/right turning machinery has been reversed:

The second shows the Erismann/Koehler experiment in which a person learned to navigate the world while wearing special glasses that make up into down (and down into up). The bicycle part comes very near the end of the video, as a culminating achievement:

Three simple rules for building a tower, if you are a fire ant

Monday, July 24th, 2017

Ig Nobel Prize winner David Hu and colleagues explain the simple rules that fire ants use when they build a tower-of-fire-ants. They explain in a new study:

Fire Ants Perpetually Rebuild Sinking Towers,” Sulisay Phonekeo, Nathan Mlot, Daria Monaenkova, David L. Hu, Craig Tovey,” Royal Society Open Science, vol. 4, 2017, 170475.

In the aftermath of a flood, fire ants, Solenopsis invicta, cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? … Here, we present models of the shape of the tower and its rate of growth. In our past work on raft construction, we found ants followed three rules, which yielded accurate predictions for raft growth rate. These rules are as follows:

1. Do not move if ants are on top of you.

2. If atop other ants, repeatedly move a short distance in a random direction.

3. Upon reaching available space adjacent to non-moving ants, stop and link with them.

4. The top layer of the tower is not stable unless there is a complete innermost ring of ants gripping each other around the rod.

We include the fourth rule based on our observations.

Here’s further detail from the study:

Sarah Zielinski has an especially nice writeup of this writeup, in Science News, with added video.

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

“Good Vibrations: A Novel Method for Sexing Turtles” [research study]

Monday, July 24th, 2017

citVibrators can be used, in a stimulating way, to study the sex of turtles. This study tells how.

Good Vibrations: A Novel Method for Sexing Turtles,” Donald T. McKnight, Hunter J. Howell, Ethan C. Hollender, and Day B. Ligon, Acta Herpetologica, vol. 12, no. 1, 2017, pp. 117-121. The authors, at Missouri State University, James Cook University, and Towson University, report:

“While most species of turtle exhibit secondary sexual dimorphisms that can be used to reliably infer sex, there are some species that are very difficult to sex, and even within many dimorphic species, it is not uncommon to encounter individuals that appear to exhibit both male and female secondary sex characteristics. Therefore, we tested the novel method of using a vibrator to sex turtles by stimulating male turtles to evert their penises. We tested this method on males of four species (three families) with known sexual dimorphisms: spiny softshell turtles (Apalone spinifera; n = 14), western chicken turtles (Deirochelys reticularia miaria; n = 17), Mississippi mud turtles (Kinosternon subrubrum hippocrepis; n = 10), and common musk turtles (Sternotherus odoratus; n = 9). The method accurately sexed 100% of A. spinifera, 64.7% of D. r. miaria, 80.0% of K. s. hippocrepis, and 55.6% of S. odoratus.”

Sternotherus odoratus, which remains difficult to sex, is also known as the “stinkpot turtle.”

NOTE: One form of vibrator is called a “rabbit vibrator.” It is not the specific kind of vibrator that was used in the study. Nor was the so-called “tame little turtle shape vibrator.”

BONUS: A performance, by humans, of the song “Good Vibrations”:

UPDATE: Jason Bittel has further details, in the Washington Post: “This $10 sex toy is helping scientists study turtles