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Time of flight

time of flight

The time for a photon created by annihilation of a positron-electron pair to reach a detector; since annihilation photons are created in pairs and travel in opposite directions at about 3 × 1010 cm/sec, measurement of the difference in arrival time at detectors with sub-nanosecond resolution allows calculation of the location of the event; the basic physics of positron emission tomography.


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Industrial Society Destroys Mind and Environment

... if the shock is unexpected and happens quickly. The physiology of fight flight reaction is very old and I do not think that this could be affected ... person has a fast or slow lifestyle. (Any real speeding up of reaction time in city dwellers, should be measured by subliminal visual testing of ...

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by animartco
Fri Mar 07, 2014 1:58 pm
 
Forum: Ecology
Topic: Industrial Society Destroys Mind and Environment
Replies: 45
Views: 46331

Re:

... small. Three things make it likely (maybe even inevitable at large timescales) : that physical laws permit such complexity to be robust, the ... as to how common intelligence is. unlike truly useful traits such as flight, it doesn't seem to appear all that often It hasn't appeared frequently ...

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by cakrit
Tue Jul 23, 2013 8:48 pm
 
Forum: Evolution
Topic: Is complexity inevitable?
Replies: 16
Views: 10029

Is complexity inevitable?

... individuals in the group. And, unlike a truly useful traits such as flight, it doesn't seem to appear all that often (and needs to be very loosely ... available in a system, it's fair to expect complexity to increase over time.

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by Darby
Tue Jul 23, 2013 4:08 pm
 
Forum: Evolution
Topic: Is complexity inevitable?
Replies: 16
Views: 10029

Is evolution as simple as we think?

... know that for sure and can never know it, since we can't go back in time. "but if evolution sees complex life as an advantage surely it ... to those with feathers to birds that can fly and back to lack of flight in aquatic penguins. However, we cannot predict (and neither can evolution) ...

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by thoffnagle
Thu Nov 29, 2012 7:39 pm
 
Forum: Evolution
Topic: Is evolution as simple as we think?
Replies: 38
Views: 22327

Evolving non "life-or-death" but useful characteristics

... me if this question has been answered before, but I've spent some time looking around for answers and haven't really found a satisfactory one. ... think there are a lot of others, like some of our fight-or-flight responses like yelling when we're startled or feeling the urge to ...

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by stephen502
Sun Jul 01, 2012 7:44 pm
 
Forum: Evolution
Topic: Evolving non "life-or-death" but useful characteristics
Replies: 5
Views: 4978
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