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[OM] Re: Level photography ;-), was [photo] Fall Mist

Subject: [OM] Re: Level photography ;-), was [photo] Fall Mist
From: "Piers Hemy" <piers@xxxxxxxx>
Date: Sun, 21 Nov 2004 18:45:03 -0000
"The leans" can be a ground-based affliction too!  As John Lind has pointed
out, balance uses not just the semi-circular canals, but feedback from
musculature (especially feet) and eyes.  A wide field of view helps to
'position' the body in its surroundings.  Now, imagine having the
semi-circular canals out of operation (or not to be trusted) while you walk
down a long dark corridor with a light at the end.  Bouncing off the walls
after over-correcting for navigational errors due to lack of visual clues as
to position!

Interesting how flight problems can be paralleled in such basic land-bound
functions!

--
Piers 
 
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of Chris Barker
Sent: 20 November 2004 22:58
To: olympus@xxxxxxxxxx
Subject: [OM] Re: Level photography ;-), was [photo] Fall Mist


Very interesting; I suppose labyrinthitis has some connection with this
condition.  But of course, some people experience something similar because
of contamination with alcohol.  And alcohol persists for several hours it
seems and accounts for poor stability after  a heavy drinking session ;-)

Going really OT now:  pilots can suffer serious spatial disorientation when
flying in poor visibility and one of the reasons can be "sub-threshold
stimulation" of the semi-circular canals.  For instance, a pilot might roll
an aircraft very gently by mistake, and the inner ear does not register the
movement.  But when he notices the error in his aircraft's attitude (say he
has 20 deg of bank instead of being wings level) and rolls quickly back to
wings level, that movement registers and his inner ear tells him that he is
now banked in the opposite direction when in fact he is wings level.  This
is called "the leans" and is insidious and rather nasty sometimes.  The
remedy is to check your instruments and not to believe your balance
mechanism.

Chris

On 20 Nov 2004, at 18:58, Piers Hemy wrote:

> That sounds righ to me Chris.  I can add that the (in terms which I 
> hope are
> appropriate) semi-circular canals' rate-of-turn and rate-of-climb 
> sensors are integrated with the auto-pilot, and issue commands to the 
> control surfaces.  And if one or more of the canals are contaminated 
> with solid matter canaliths), the measured flows in the liquid will be 
> many times greater than normal, leading to commensurately great 
> adjustments to the controls.  In the experience one such sufferer, 
> turning the head in a particular direction while standing was 
> interpreted as a fall to the left, causing an immediate relaxation of 
> the right leg muscles, and a pretty sudden fall to the right.  An 
> 'interesting' experience. As was the cure 
> http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/
> Vertigo_benig
> n_paroxysmal_positional_vertigo?OpenDocument
>
> --
> Piers
>
<|_:-)_|>
C M I Barker
Cambridgeshire, Great Britain.
+44 (0)7092 251126
http://www.threeshoes.co.uk
http://homepage.mac.com/zuiko


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