There is a lot of misinformation because Korea wants the world to believe TKD is an ancient art. Tae kwon do is NOT based on taekkyon or other so called "ancient" arts from Korea and is infact based on karate and a little chuan fa.
Another study showed that human subjects - after receiving 100 milligrams of caffeine - had increased activity in brain regions located in the frontal lobe, where a part of the working memory network is located, and the anterior cingulate cortex, a part of the brain that controls attention. The caffeinated subjects also performed better on the memory tasks.
If you get water flowing fast enough, it can cut metal.More Info
A waterjet is a tool used in machine shops to cut metal parts with a (very) high-pressure stream of water. As amazing as it sounds, if you get water flowing fast enough it can actually cut metal.
Think of a waterjet as something with about 30 times the pressure of the power washer wand at your local car wash. Power washing at car washes is an everyday example of a dirt film being "cut" off the body, wheels and tires of an automobile.
The key to cutting metal with water is to keep the spray coherent. Waterjets are able to cut because the spray is channeled through a very narrow jeweled nozzle at a very high pressure to keep the spray coherent. Unlike metal cutters, a waterjet never gets dull and it cannot overheat.