Why Use Dinosaur Poop to Repair Sheep Bones?

July 27th, 2017

Roy Bloebaum used fossilized dinosaur poop to repair sheep bones. The repair of bones can be an intricate undertaking. Dr. Bloebaum (and colleagues!) hoped to demonstrate how easy it can be to make iffy assumptions. They chose dinosaur feces fossil material to attract attention that could then be focused on certain intellectual aspects of bone repair. They describe this, in technical language, in a newly published study:

Transcortical or intracondylar? Which model is accurate for predicting biomaterial attachment in total joint replacement?” Roy D. Bloebaum [pictured here], Nicole T. Abdo, Aaron A. Hofmann, Richard T. Epperson, Raymond E. Olsen, and Ornusa Chalayon, Journal of Biomedical Materials Research Part B, epub 2017. They authors, at the Bone & Joint Research Laboratory, DVA SLC HCS, Salt Lake City, Utah, and the University of Utah, report:

Despite four decades of research on material and porous coatings intended for cementless fixation in total joint replacement (TJR), aseptic mechanical loosening unrelated to particulate disease remains a concern….

Porous-coated commercially pure titanium implants (Ti-Coat) were from Thortex Inc., Portland Oregon and were used as the material to test the hypothesis (control). Commercially pure titanium has been shown to provide successful attachment clinically in TJR. Coprolite implants, from David Gillette with Utah State University, commonly known as petrified dinosaur poop (Dino), were used to establish a dramatic understanding that even this unique material (which would never be used in TJR) might demonstrate that bone could hypothetically bridge a 500 mm gap at the transcortical location, but possibly not at the weight-bearing intracondylar location….

In conclusion, the results of this investigation emphasize that biomaterial scientists, manufacturers, investigators, and orthopedic surgeons should be aware of the inferior healing properties of cancellous [the inner, spongily-structured, portion of] bone as compared to cortical [the outer, more-compactly-structured portion of] bone and how these results suggest a false-positive nature of the transcortical model in TJR. The results showed that even petrified dinosaur feces could be mechanically stable in the transcortical model.

Here are further details from the study:

(Thank to Donald W. Howie for bringing this to our attention.)

Sad News: Daedalus (David Jones) is gone

July 27th, 2017

We’ve just seen reports that our friend David Jones — best known in the science world as “Daedalus” — died. “Daedalus” was the name of the column David created and wrote, in which he did something that, as far as I am aware, was a unique way to make people laugh, then think.

Each Daedalus column would describe an imagined invention. Usually there would be something quite intentionally wrong in the details — a violation of some law of nature, typically — but in a way that was not immediately obvious. The greatest pleasure, should you the reader care to indulge, came in figuring out what exactly made that invention so very odd or impossible. (He waxed on, a bit, about one of his favorite specialties — perpetual motion machines — in a 1983 piece in New Scientist.)

The column ran for many years in New Scientist magazine, and then moved to Nature. Some of the best Daedalus columns were collected and made into two books: The inventions of Daedalus: A Compendium of Plausible Schemes; and The Further Inventions of Daedalus.

David was fond of pointing out, later in life, that many of the ideas he presented in the column accurately foreshadowed things later honored with Nobel Prizes, and a few with Ig Nobel Prizes. That and other musings are in David’s book The Aha! Moment.

Wikipedia has a partial summary of some of the things David did. Better: Conor Lawless visited David in 2010, then produced a writeup with lots of photos.

The photo here shows David at the 2001 Ig Nobel Prize ceremony. He was not in the best of health, having lost most his ability to walk — but said he would come to demonstrate to himself and the world that he could still do things he wanted to do. David traveled from his home in England to the Ig Nobel ceremony at Harvard University, in the US (and that was in the weeks just after the September 11 attack on New York — travel was not simple for anyone).

In the ceremony, David did one of the first 24/7 lectures. This photo shows that moment. You can read his words, and see video of his actual performance.

While David was in town, he and I and Jerry Lettvin and our families had dinner together. The meal featured a spectacular competition: David Jones and Jerry Lettvin — two of the most inventive, science-loving minds on the planet — gleefully shooting each other’s musings full of holes.


Towards a robotic jumping flea (new study)

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]

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

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: