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Medicine

Brain Decline Begins At Age 27 381

Posted by timothy
from the mine-started-before-that dept.
krou writes "The BBC is reporting that a new study suggests that our mental abilities start to dwindle at 27 after peaking at 22, and 27 could be seen as the 'start of old age.' The seven-year study, by Professor Timothy Salthouse of the University of Virginia, looked at 2,000 healthy people aged 18-60, and used a number of mental agility tests already used to spot signs of dementia. 'The first age at which there was any marked decline was at 27 in tests of brain speed, reasoning and visual puzzle-solving ability. Things like memory stayed intact until the age of 37, on average, while abilities based on accumulated knowledge, such as performance on tests of vocabulary or general information, increased until the age of 60.'"

Comment: Re:Iron Man's Suit Defies Physics -- Mostly (Score 2, Interesting) 279

by John Carmack (#23266718) Attached to: The Science of Iron Man
Hydrogen peroxide powered rocket packs fly for around 30 seconds, because they have a specific impulse of around 125, meaning that one pound of propellant can make 125 pound-seconds of thrust, meaning that it takes about two pounds of propellant for every second you are in the air. Mass ratios are low for anything strapped to a human, so the exponential nature of the rocket equation can be safely ignored.

A pretty hot (both literally and figuratively) bipropellant rocket could manage about twice the specific impulse, and you could carry somewhat heavier tanks, but two minutes of flight on a rocket pack is probably about the upper limit with conventional propellants.

However, an actual jet pack that used atmospheric oxygen could have an Isp ten times higher, allowing theoretical flights of fifteen minutes or so. Here, it really is a matter of technical development, since jet engines have thrust to weight ratios too low to make it practical. There is movement on this technical front, but it will still take a while.

John Carmack

Comment: This man's idea of an ULTIMATE game (Score 1) 633

by vosbert (#15485507) Attached to: Just Let Me Play!
All he needs is a modded playstation to play 3 more minutes of a movie dvd every time he hits a button. In this manner, he knows exactly how long the "game" will take (approximately 2 hours), and he will never get stuck on a level. There would be absolutely nothing to unlock, and the game will have a definite beginning and an ending. What's the fun of a non-challenging game? Why do all games have to follow the RTS format? Where's the growth in character, where you can see a measly being advance and become powerful? Or seriously, just forget games and watch movies.

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