Henrik Ehrsson uses mannequins, rubber arms and virtual reality to create body illusions, all in the name of neuroscience.

"It is not every day that you are separated from your body and then stabbed in the chest with a kitchen knife. But such experiences are routine in the lab of Henrik Ehrsson, a neuroscientist at the Karolinska Institute in Stockholm, who uses illusions to probe, stretch and displace people's sense of self."




(via Nature)

How coral snakes cause excruciating pain

(via Not Exactly Rocket Science)



"MitTx is a toxin of two halves, neither of which do anything alone. When they unite, the two subunits – MitTX-a and MitTx-b – activate proteins called acid-sensing ion channels, or ASICs. These act as gates that sit on the surface of neurons. When they detect an acidic environment, they open up and let ions into the cells, causing them to fire.

ASICs can be triggered by tissue injuries, inflammation or build-ups of lactic acid, and they tell our bodies that something is wrong. The coral snake hijacks this early warning system, by producing chemicals that turbo-charge it. Bohlen and Chesler found that when MitTx is around, acidic environments trigger a much stronger response from the ASICs. As a result, some sensory neurons fire over a thousand times more strongly than they normally would, and they take far longer to return to normal."

Hagfish filmed choking sharks with slime, and actively hunting fish | Not Exactly Rocket Science | Discover Magazine

"The hagfish releases a quick-setting slime that clogs up the predator’s gills, causing it to gag, choke and flee. Scientists have known about this repulsive defence for decades, but Vincent Zintzen has finally filmed it in the wild. His videos also prove that hagfish, generally thought to be scavengers of the abyss, are also active hunters that can drag tiny fish from their burrows." (Not Exactly Rocket Science)

Fish, flesh, or fowl, commend all summer long

One number unites anything that flies or swims

(via io9)

"...the Strouhal Number, invented by Vincenc Strouhal just as the 1800s turned into the 1900s, is a way to compare the different species in a way that fits their massively different techniques into a narrow range. Almost all flapping creatures fit into a Strouhal range of 0.20 to 0.40. Birds of prey tend to circle around the 0.24 radius while bats are up in the 0.26 range. Dolphins and whales are an impressive 0.28. Different species with different evolutionary histories, tend to cluster around different Strouhal Numbers. This one unitless number shows the whole of evolutionary history."

Hummingbirds dive to sing with their tails

(from Discover)

"Many birds sing to woo females, but some hummingbirds go to great lengths to do so. They climb to between 5 and 40 metres before plummeting past perched females in death-defying dives. They pull up at the last minute, spread their tail feathers and produce a loud chirpy song. The song comes not from the birds' mouths, but from their tails. "

Pendulum Waves

"Fifteen uncoupled simple pendulums of monotonically increasing lengths dance together to produce visual traveling waves, standing waves, beating, and (seemingly) random motion."

This is... this is kind of mind blowing.

Squid, Octopus, Cuttlefish: Masters Of Camouflage

(link)

The Fool on the Hill ...

Click to start. Hang on for the ride.

Peacock Spider

Jumping spiders are the most adorable.

Narration by Jürgen Otto

Magazine Babbage's Difference Engine built entirely in Lego

(via Wired)

http://cdni.wired.co.uk/620x413/a_c/5504_WiredUK_Hero_lego_04_620x413.jpg

This working computer uses bits -- of Lego. Andrew Carol created a version of Charles Babbage's Difference Engine, built entirely from plastic building blocks. Babbage planned it in the 1840s but never realised it. Carol started six years ago and drew on his 15 years' experience as a software engineer at Apple: "I would work on one adder unit, modifying it until I could get as many of the bugs out as possible," says the Cupertino-based 47-year-old. "When you get one working, you can use it everywhere in the engine." The finished iteration uses about 2,000 Lego parts but the crank-operated computer is not as powerful as Babbage's would have been. "His would have been accurately made of brass. Mine's made out of a children's plastic toy."

Apple engineer re-creates 2,000-year-old Greek computer. With Legos.

(via The Raw Feed)

"An uber-egghead named Andrew Carol, who works as a software engineer at Apple, has re-created the amazing Antikythera Mechanism using Legos. Ancient Greeks created the device in 100 B.C. to predict astronomical events. This is incredible."

The sound of π

here.

Why we have to get rid of pi for the sake of good math

(via io9)
"...

I believe you've mentioned that tau reveals connections that pi does not. Could you provide an example of this?

The canonical example involves radian angle measure. For example, a right angle is a quarter turn of a circle, and its measure is tau over four, or one-quarter tau. Using pi, the same angle is pi over two, or one-half pi, which obscures the natural relationship between angle measure and the circle constant. As discussed in The Tau Manifesto, using tau also helps reveal the relationship between complex exponentiation and rotations in the complex plane. The geometric meaning of Euler's identity, for instance, is much clearer when written in terms of tau.

Full size

And what about counterexamples where pi seems more useful? For instance, the area of a circle formula (A = πr^2) seems far more elegant with pi than with tau.

The formula for circular area is actually The Tau Manifesto's coup de grâce. You need to read the manifesto to get the full impact of the argument, but the short version is that the area of a circle has a natural factor of a half that disappears when using pi.

Incidentally, all counterexamples I know of are addressed in The Tau Manifesto. When they hear about the basic idea of tau, some people (without reading The Tau Manifesto) object that "tau ruins Euler's identity" or "the formula for circular area is better with pi". When questions about software are answered in the software's documentation, computer programmers are notorious for responding with "RTFM", which stands for "Read The *ahem* Fine Manual". In this vein, I urge potential correspondents to Read The Fine Manifesto before voicing their objections.

..."

Chicken-driven steadicam

Check it out at http://www.youtube.com/watch?v=UytSNlHw8J8

(Thanks to Thomas Sullivan).

Reference: http://www.acoollink.com/chickens-steady-head/