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LORNA GIBSON: My
name's Lorna Gibson.

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I'm the professor
for 3.054, it's

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a course on cellular solids.

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And I've been working
on cellular solids

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since I was a graduate
student, since I did my Ph.D.

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And cellular solids
are materials

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that are made up of
an interconnected

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network of struts or plates.

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And there's examples like
engineering honeycombs

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and foams, and there's
lots of examples in nature.

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Things like wood and cork and
there's a type of porous bone.

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And there's lots of
examples in medicine too.

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Tissue engineering
scaffolds, for example.

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So my background is
in civil engineering,

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and in civil engineering
we study structures.

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And typically people
think of large structures

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like bridges or buildings.

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But in fact when we analyze
the cellular solids,

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we use the same
kind of mechanics.

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It's just the scale
is very much smaller.

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So we're looking at structures
where the scale might

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be hundreds of microns or
millimeters, things like that,

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but the same sort of mechanical
principles apply to that.

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OK, so I grew up in
Niagara Falls, in Ontario.

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And people always
think of Niagara Falls

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as being the waterfall
and all the tourist stuff,

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there's a casino there now.

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But in fact, there's loads and
loads of big civil engineering

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works in Niagara Falls,
mostly associated

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with the hydroelectric
power station.

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So when they make hydroelectric
power in Niagara Falls,

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the power station is actually
about a mile downstream

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from the Falls.

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And what they do is they have
a big hydraulic gate that

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goes into the river
and it diverts water

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from the river above the Falls
into a whole series of canals

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and tunnels and there's
a big reservoir where

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they store water.

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And then the water
from this reservoir

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goes into the
penstocks, the tubes

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that go down to the turbines
and then make the electricity.

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Niagara Falls is not a big town,
but if you drive around Niagara

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Falls, you see these canals,
you see the reservoir,

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you see the big power station.

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And so there's
these really huge,

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impressive civil
engineering works.

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And my father worked for
an engineering company

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in Niagara Falls
and they specialized

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in the design of
hydroelectric power stations,

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and I think that's how I got
interested in engineering.

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So I've been interested in
bird watching for some time.

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Mostly just because
birds are beautiful

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and there's all sorts
of interesting behaviors

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you can see with birds.

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But since I started
doing research

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on cellular solids
and, in particular,

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teaching this course,
I realize there's

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lots of examples of things
about birds that have

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to do with cellular materials.

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So for instance,
some people had once

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told me that woodpeckers
avoid head injury and brain

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injury by having a
special cellular material

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in between their
brain and their skull.

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And that this acted kind of
like a foam in a bicycle helmet.

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That it would absorb the
energy of the impact.

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And I thought oh, well,
I like bird watching

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and I study cellular materials,
I should find out about this.

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So I started looking
into it and people

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had looked at the anatomy of
the woodpecker skull and brain.

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And, in fact, there is no
special cellular material.

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But by that point, I
was kind of hooked.

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And I actually did a
project at one point

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looking at why it
was that woodpeckers

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don't get brain injury.

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And it's largely a scaling law.

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It has to do with the fact that
their brains are very small.

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Another aspect of birds that
has to do with cellular solids

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is how birds make
themselves very light.

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And here we have an owl skull.

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This owl, unfortunately,
had an accident with a car.

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But somebody picked up its body
and took it to Mass Audubon,

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and I got this from somebody
at the Massachusetts Audubon

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Society.

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And if you look at
the skull-- I don't

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know if you can do
a close-up here--

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if you look at
the skull, you can

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see there's a dense layer
of bone on the outside

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and there's another dense
layer bone on the inside,

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and there's a sort of foamy
layer bone in between.

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And that's called a
sandwich structure.

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And this foamy type of bone
is called trabecular bone.

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And that's one of the
things that I study.

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And it turns out that
particular structure gives you

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a very stiff, strong,
lightweight structure.

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So you can see an example of
how cellular materials are

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used in engineering but here
sort of manifested in the owl's

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skull in making the
skull very light.