A.
An Alternative to Gasoline
Narrator:
This is Science Today. You may not think about
it tomorrow, but eventually gasoline is going to
run out. The search for alternative fuels is on,
and engineer Jim Heffel of the University of California,
Riverside has a likely candidate: hydrogen. He and
his team have modified a conventional truck to run
on tanks of the lighter-than-air element.
Heffel:
Our truck has the same engine that came with the
vehicle. We did a few modifications to the engine,
mainly to improve performance. Hydrogen has a little
less energy content than gasoline, so to keep the
same performance we've added a turbocharger.
Narrator:
But that same lower energy content has safety
advantages, too.
Heffel:
Studies have been done where they've punctured a
tank and lit it on fire and because the flame emits
a lot less heat than, say, natural gas or gasoline,
you can get real close to it. What's nice about
that is that the chances of catching other things
on fire are reduced.
Narrator:
Besides that, hydrogen is non-toxic, non-polluting,
and won't run out -- because it's made from water.
For Science Today, I'm Steve Tokar.
B.
DNA Testing: Fraught With Peril
Narrator:
This is Science Today. More suspects are being
convicted -- or freed -- based on DNA testing. Criminologist
William Thompson of the University of California,
Irvine says the problem is that juries often don't
understand exactly what the test means.
Thomson:
When the evidence is used to incriminate somebody,
basically the laboratory is saying that they find
a match or a similarity between the genetic characteristics
of two samples. And because the genetic characteristics
of samples is not something that people in their
everyday experience know a lot about, you have to
say something to the jury to explain to them the
meaning of a match.
Narrator:
Thompson says statistics like "one in a
billion match" are meaningless by themselves.
DNA samples are compared at only a few spots along
the sample -- and there's plenty of room for error.
Thompson:
And the value of a match across several sites for
incriminating somebody varies dramatically depending
on how rare the matching characteristics are and
how certain we are that what's being called a match
is really a match.
Narrator:
For Science Today, I'm Steve Tokar.
C.
No Chemicals On the Horizon
Narrator:
This is Science Today. A pest called the codling
moth causes millions of dollars in damage every
year to apples, walnuts and other crops. Entomologist
Lou Falcon of the University of California, Berkeley
says that traditionally, conventional pesticides
have kept it under control.
Falcon:
However in recent years resistance has been showing
up, and it appears that it takes more chemical now
than it did a few years ago. And even with more
chemical the control appears to be failing, so that
it may not be around too much longer.
Narrator:
Fortunately, the government has approved an
organic pesticide developed by Falcon -- a virus
that attacks only the codling moth -- and just in
time too. There are no new chemical pesticides on
the horizon.
Falcon:
The development of new pesticides is very very very
slow, extremely expensive, and the chemical industry
is really not producing or developing very many
new pesticides. So not only is it a matter of supplanting,
but it's a matter of finding alternatives.
Narrator:
For Science Today, I'm Steve Tokar.
D.
A Model Theory
Narrator:
This is Science Today. To look at the details
of a molecule or the interior of the earth, scientists
usually use 3-D graphics on a computer screen. Mike
Bailey, a supercomputer expert at the University
of California, San Diego, has a new device that
makes physical models you can hold in your hand.
He says the models help scientists see things in
an entirely new way.
Bailey:
The scientists have seen features in the solid models
that they completely missed through months or years
of study on computer graphics screens.
Narrator:
The question is why. Bailey has a few theories.
One is that you can run your fingers along a model.
Bailey:
And as you run your fingers through the valleys
and the peaks on different models, you get some
better sense of what the geometry is.
Narrator:
Another theory is that the focus of your eyes
changes.
Bailey:
When you look at a graphics screen, no matter
what, it's a flat screen and everything focuses
at the same distance. Whereas if you look at this,
your eyes are constantly shifting back and forth
in focus, and we believe that gives you some kind
of clues as to the depth.
Narrator:
Bailey is designing experiments to test his
theories. For Science Today, I'm Steve Tokar.
E.
And You Thought It Was Just Grass
Narrator:
And you thought it was just a baseball field.
This is Science Today. Steve Cockerham, an agricultural
expert at the University of California, Riverside,
was asked to supply a new kind of natural grass
that would grow indoors in a domed professional
baseball stadium. That was the easy part. A pro
baseball field has to be totally even so the ball
won't take a bad bounce...
Cockerham:
It has to be able to heal quickly from injury, if
there's injury from a player skidding or tearing
it up or whatever. And then the color has to be
satisfactory, a good dark green color. The esthetics
of this are almost as important as the performance.
Narrator:
Plus, it has to grow quickly. But you have to
be able to mow it down to half an inch. And...
Cockerham:
The texture of the grass has to be such that
it looks like a carpet, it can't be too coarse or
too fine. It has to be such that it will give when
a cleat hangs up in it so that it doesn't cause
an injury. So these are some of the characteristics
we look for.
Narrator:
For Science Today, I'm Steve Tokar.
