[clug] Arlec surge protector
a.janke at gmail.com
Wed Mar 17 16:42:36 MDT 2010
> In the world of Physics, there's Energy/Work and Power (Energy per unit
> time), Joules and Watts.
> In computing we have MIPS (work per unit time), so what's the equivalent
> of Joules??
Probably the closest is rate of ATP uptake (for the brain). This is
difficult to measure though and instead is generally measured as glucose
uptake which is in turn converted to ATP in the mitochondria in the
post-synaptic density. This can be measure using PET by tagging some
of the this glucose (2-deoxyglucose) and measuring the amount of it
you injected as
compared to the amount that is still in the persons bloodstream vs the
signal from the brain.
> And how does that relate to 'thunks' by people??
And here is the problem. The brain as a whole has a relatively
constant energy metabolism, it goes down slightly when we go to
sleep and up a bit when we wake up but beyond that nigh on constant.
This is mainly as the brain has a heck of a lot of maintenance work to
do just to maintain normal function:
* cleaning all the wires
* maintaining old memory circuits and keeping them firing
* keeping the insulation healthy
* keeping voltage potentials good in case they need to fire
* doing all the subconscious unimportant things like breathing,
heart rate monitoring, temperature regulation, endocrine function
The support cells are called Glial tissue and do everything in the
brain except conduct sparks.
> Is there work done on measuring/reporting the computational 'cycles' of
> brains on standard tasks??
Absolutely, this is done with either PET or fMRI and are those pretty
images you see in journals from time to time with "red blobs on
brains". _Quantifying_ the effect is difficult as all you are
measuring in the fMRI case is a relative increase in blood flow/volume
in the venous capillary bed that is next to a bunch of neurons. But
certainly ratios or size of effects can be measured.
This method of measuring the amount of work has been been used (for
example) in an
attempt to differentiate people in early age who will go on to get
dementia. The theory is that their brains have to work "harder" to
figure problems out early on.
So sad to say, no you probably can't loose weight by just "thinking".
> We will now resume normal programming... [Silence] :-)
(a.janke at gmail.com || http://a.janke.googlepages.com/)
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