Helmet ******s

David Kerber wrote:

Do you have any cites for the claim that helmets "amplify the rotational
component" of a head impact to any significant degree? I don't need to
see them for the fact that rotational acclerations are more damaging to
the brain; that is well-known, and has been for many years.


Curnow WJ "The efficacy of bicycle helmets against brain injury", Accident
Analysis and Prevention, Vol 35, pp287-292 (2003)

http://tinyurl.com/3hnav (abstract plus link if you are registered to full
article)

In other sports, the role of helmets in increasing rotational injuries is also
known. See for example:
http://www.ipvca.org/coaches_connect...al_helmets.htm

Tony

On Sat, 7 Feb 2004 20:03:46 -0500, David Kerber
wrote in message
:

Do you have any cites for the claim that helmets "amplify the rotational
component" of a head impact to any significant degree?

Cites? No, the jury is still out. But it is a concern whihc has been
raised by a number of doctors, and the proposed mechanism is credible
- it is also one possible explanation for the rise in seriousness of
injuries since 1985, as helmets have become more common. Other
factors could also account for this.

But because the difference in riding style is small for me, I think I
personally gain in _overall_ safety. I.E. the small increase (not
noticeable by me) in risky behavior is more than compensated for by the
increased protection from the helmet. Obviously that will not be the
case for every cyclist.

That's your choice. I don't see from the data anything which makes a
good case for even strong encouragement of helmet use, let alone the
current emphasis on helmet use to the exclusion of all else.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

On Sat, 7 Feb 2004 20:14:07 -0500, David Kerber
wrote in message
:

most EE's of my acquaintance (including me) aren't
that big into theory to remember the basic equations years later, even
though they certainly learned them at one time.

Always assuming that their lecturers, call them for the sake of
argument Professor Hammond, made the bloody things comprehensiuble in
the first place.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

On Sun, 08 Feb 2004 01:45:01 GMT, Graeme
wrote in message
:

EE = electrical engineer? That's me (well, at least if what your degree was
defines you). V=IR is about all I can remember instantly, most other stuff
takes a bit of thinking or a book

Scarily true. I can't remember most calculus any more.

(B.Eng Hons, Electrical Engineering)

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

"Just zis Guy, you know?" wrote in
:
Scarily true. I can't remember most calculus any more.

(B.Eng Hons, Electrical Engineering)

Snap! This is getting scary Guy, I find myself agreeing with your posts
more and more, and now I find we both have the same degree. I live in fear
of waking up some day with a dodgy moustache (but I'll live with it if it
comes with the associated recumbent bike).

;-)

Graeme

Curnow WJ "The efficacy of bicycle helmets against brain injury", Accident
Analysis and Prevention, Vol 35, pp287-292 (2003)

http://tinyurl.com/3hnav (abstract plus link if you are registered to full
article)

In other sports, the role of helmets in increasing rotational injuries is also
known. See for example:
http://www.ipvca.org/coaches_connect...al_helmets.htm

wot he said, and

Bicyclists, helmets and head injuries: a rider-based study of helmet use and
effectiveness Wasserman RC, Waller JA, Monty MJ, Emery AB, Robinson DR 1988.
American Journal of Public Health: 1988 Sep;78(9):1220-1

suggests that helmeted riders are seven times more likely to hit their heads. I
guess that this is something to do with the control groups, but it's not hard to
think of several ways that helmets make you more likely to headbutt things
(size, weight, risk comp etc).


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In article ,
David Kerber wrote:
In article ,
says...

Exactly. And that leaves that much less energy to be transmitted to my
skull. It won't absorb it all, but it will absorb whatever it can,
reducing what hits my scull.

And at the same time aplifying the rotational component which is the
most common cause of brain injury.

Do you have any cites for the claim that helmets "amplify the rotational
component" of a head impact to any significant degree? I don't need to
see them for the fact that rotational acclerations are more damaging to
the brain; that is well-known, and has been for many years.

I haven't seen any analyses of experimental data, though I have heard
that there may have been a little for motorcyclists and/or horse
riders. It is, however, immediate from the physics involved that they
are very LIKELY to do that.

Most accidents involving reasonably cautious cyclists have the cyclist
coming off sideways - even being hit from behind at a fairly low
relative speed will do that. If someone comes off sideways, the impact
is on hip, shoulder and sometimes knee and elbow. Because a helmet
increases both the width and the moment of the head by a significant
factor, it is very likely to cause head/helmet contact where it would
not otherwise have happened. Q.E.D.

What isn't so easy is to assign probabilities and severities to this,
but it is absolutely clear that the effect must exist, unless you
deny the reality of elementary physics (as many people and most of
our Lords and Masters do).


Regards,
Nick Maclaren.

On Sun, 08 Feb 2004 11:07:25 GMT, Graeme
wrote in message
:

This is getting scary Guy, I find myself agreeing with your posts
more and more, and now I find we both have the same degree.

Luke, I am your father...

Where did you do the B.Eng? If it was Southampton please be aware
that the world will have reached a degree of smallness where China may
require a second layer.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

On Sat, 07 Feb 2004 19:26:05 -0800,
Benjamin Lewis wrote:
David Kerber wrote:

God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J +
@D/@t," and there was light.

So are you an EE or a Physicist?

Physicist.

Tim.

That was my guess; most EE's of my acquaintance (including me) aren't
that big into theory to remember the basic equations years later, even
though they certainly learned them at one time.

Also, I was under the impression that EEs usually express these in a
different format.

So do Physicists nowadays but, IIRC "dF = 0" just doesn't have the same
ring to it.

Tim.

--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t,"
and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

"Just zis Guy, you know?" wrote in
:

Luke, I am your father...

That explains it, the Dark Side has been calling for some years now.
Unfortunately SWMBO has been calling for different things (weddings,
moving to the other side of the world etc.) which means my bank balance
seldom reaches the relevant level (although I wouldn't have to pay
shipping on a Greenspeed trike now :-)

Where did you do the B.Eng? If it was Southampton please be aware
that the world will have reached a degree of smallness where China may
require a second layer.

Phew! It was Edinburgh. The only link I have to Southampton is having
been there a couple of times visiting the council for work purposes. So
the mutation may not reach the moustache stage.

Mind you, I'm sure I've got a virtual 'tache, here I am sitting in
Australia and I'm listening to Radio 4 via broadband- Gardener's
Question Time even! It may even be a virtual beard, pipe and slippers :-O

:-)

Graeme