Sandy wrote:
> Dans le message de
> news:[email protected],
> 41 <[email protected]>
> > Sandy wrote:
> >> Dans le message de
> >> news:[email protected],
> >> 41 <[email protected]>
> >>> Sandy wrote:
> >>>> Dans le message de
> >>>> news:[email protected],
> >>>> 41 <[email protected]>
> >>>>
> >>>>> even without any
> >>>>> helmet, you will sustain a mortal injury to your brain before your
> >>>>> skull fractures.
> >>>>
> >>>> You may want to think about that, again.
> >>>
> >>> Or you. The original head injury standards for helmets w ere based on
> >>> prevention of skull fractures and those were 500 G. With the move to
> >>> the prevention of brain injury instead that went down to the 300 G
> >>> that we still see in today's Snell standards.
> >>>
> >>> <http://www.smf.org/articles/h elmet_development.html>
> >>
> >> OR
> >>
> >> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1443374&dopt=Abstract
> >>
> >> http://www.emedicine.com/emerg/byname/epidural-hematoma.htm
> >>
> >> http://depts.washington.edu/hiprc/practices/topic/bicycles/helmeteffect.html
> >>
> >> Take a look again at what you wrote. It's not a sin to see it may
> >> be far from the truth.
> >
> > No, you first. The references you supplied show you (a) did not read
> > what I wrote and (b) do not understand the problem, AT ALL. The first
> > two are entirely irrelevant and the third, containing capsule
> > summaries
> > of other studies, might only possibly be relevant (in fact, those
> > studies do not have the detail necessary to know). You seem to think I
> > (a) said it was impossible to have a skull fracture without first
> > dying, and (b) that it is impossible to have a skull fracture from a
> > deceleration injury without dying. Indeed you might get that
> > impression
> > from just the part you snipped out. The first mis-reading shows a
> > complete misunderstanding of the entire problem, the second shows an
> > only somewhat more refined misunderstanding of the entire problem.
> > Hint: read e.g. the Snell standards, FULLY. And why not, what I wrote
> > as well, noting what parts of those Snell standards I do and do not
> > refer to:
> >
> > #> If had landed square on
> > #> the top right side of my head without my helmet, I probably would
> > have
> > #> fractured my skull. I believe that because I separated my
> > shoulder,
> >
> > #> and it hit second.
> >
> > #It's hard to see how that would have happened without your brain
> > being
> > #scrambled first. At the 300g deceleration against a flat surace, you
> > #are not supposed to be at the limit of skull fracture, but you are
> > #supposed to be at the limit of brain scrambling. In other words, by
> > the
> > #time a bicycle helmet (as opposed to a hard hat) is protecting you
> > #against skull fracture, you are alr eady dead, i.e., even without any
> > #helmet, you will sustain a mortal injury to your brain before your
> > #skull fractures. That is not the case if it is you who is at rest
> > and
> >
> > #the object that is flying against you, because in that cas e, your
> > #deceleration is 0g no matter what, comfortably below the 300g limit.
> > #But that is not what bicycle helmets are designed for.
>
> Last one - patience exhausted. But I'll read your reply.
Oh, be serious. You didn't even have the patience to read it the first
time, much less the second, since you merely repeat your previous
error:
> You state that brain fatality will occur be fore a fracture. Take a look
> upstairs.
>
No, you take a look: I said that occurs under certain conditions, which
you omit because you do not understand: your second reference describes
impact by a moving object to a stationary head, which I explicitly
excluded from the situation at hand. The first describes basilar skull
fracture, a rare fracture that occurs either from blows to the head or
extreme forces to the torso not involving the head, as in auto crashes
but not bicycle crashes. The third reference may possibly refer to
situations covered by my statement, but there is no detail so it is
impossible to know.
I will spell it out for you but I do understand it will do no good: as
specified in the Snell, and other standards, impacts may be against
surfaces of many different shapes, from flat to point contact. The
results of impacts to such surfaces differ widely. I referred only to
the best-case scenario for the skull, impact against a flat surface.
Impact to the top right side as described by Beattie, as I replied to,
causing rotation in the coronal plane, is by contrast one of the
worst-case scenarios for brain injury. Impact against a non-flat
surface can easily result in skull fracture before devastating brain
injury. And yes, of course all of this is in terms of likelihoods, as
all the biomechanical head injury data is all based on statistical
norms and probabilities: some skulls are indeed thicker, and numb-er,
than others.
<http://www.bartleby.com/107/18.html>
As you, or at least someone who reads things, can see from the table
[note: the entries in the last three rows are displaced by one column],
the ultimate compressive strength of bone is about 3x that of white
oak, about 50% greater than granite, and about one-third that of steel,
at considerably less than one-third the weight, i.e. the
strength-to-weight ratio of bone exceeds that of medium steel by about
25%. Let's see; how would that compare with styrofoam exactly?
> Dylsxeaie is not an excuse.
a
