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A.
Testosterone May Protect Older Men's Brains
Narrator:
This is Science Today. A recent study has demonstrated
that older men with higher levels of testosterone
have better brain function than men with lower levels.
Kristine Yaffe of the University of California,
San Francisco, says the research involved men over
the age of 65.
Yaffe:
We did a series of cognitive assessments-so
we did a number of very standardized cognitive tests-and
then we measured their sex hormones in the body.
And it turned out that the men who had the higher
levels of testosterone did much better on the cognitive
tests-on all three of the cognitive tests we administered-than
men who had the lower levels.
Narrator:
Yaffe says the findings suggest that taking testosterone
supplements may protect the brain from diseases
like Alzheimer's. But she adds that future clinical
trials are needed to determine if such supplements
would benefit the brain over time.
Yaffe:
Our data is preliminary. I would caution people
from taking drugs, over the counter or prescription,
specifically to help with their memory or prevent
Alzheimer's based on our results.
Narrator:
For Science Today, I'm Larissa Branin.
B.
What Nicotine Does to the Brain
Narrator:
This is Science Today. Researchers have found for
the first time that nicotine causes selective degeneration
in the brain. In fact, UCLA neuroscientist Gaylord
Ellison, who conducted the study, says it's the most
selective degeneration in the brain he's ever seen,
in that only one tract of the brain is affected.
Ellison: It's only one tract,
but when I say one tract, I'm talking about millions
of axons. It's one tract, but it's an important tract.
Narrator: It's called the fasciculus
retroflexus, a region of the brain just above the
thalamus, and it has two halves. One half Ellison
discovered in previous research, is damaged by drugs
such as amphetamines, cocaine and ecstasy. Now, Ellison's
research team has found that nicotine causes neurotoxicity
in the other half.
Ellison:
So perhaps
by understanding better these two halves of the neurotoxicity,
one could develop strategies for reducing neurotoxic
effects on one side versus the other.
Narrator:
For
Science Today, I'm Larissa Branin.
C.
The Important Role of Fathers in Child Development
Narrator:
This is Science Today. Human behavior scientists generally
agree that mothers play a very large and lasting role
in a child's life - especially if they are home with
the child more often than the father. But that's not
to say fathers don't contribute to their child's well-being.
In fact, child development expert Brenda Bryant of
the University of California, Davis, says a father's
direct interaction makes a great impact.
Bryant:
And we find that these occur early in life and
that makes them, once they're attached, make them
a source for children to relieve their stress and
enable them to explore more, learn more, because they're
not as worried. So fathers play that role as well
as the mother.
Narrator:
Fathers also contribute to their child's emotional
development in ways that are uniquely different from
mothers.
Bryant:
They're more likely to make up games and mothers are
more likely to play traditional, established games,
so fathers are introducing creativity and breaking
rules or creating their own rules that can be very
helpful to kids.
Narrator:
For Science Today, I'm Larissa Branin.
D.
Revising the Standard Model of Physics
Narrator:
This is Science Today. Recent research on subatomic
particles called neutrinos may alter some of the most
basic scientific theories. Physicist Kevin Lesko of
the Lawrence Berkeley National Laboratory worked on
the experiments at Canada's Sudbury Neutrino Observatory.
He says the results show that neutrinos change type
as they travel from the sun to the earth.
Lesko:
Previously we assumed the families were distinct,
there was no oscillations or mixing between the families,
and that they were all massless, and that what had
gone into the Standard Model of physics, which has
been around for the last thirty years.
Narrator:
Particles other than neutrinos have been shown to
mix, but these transformations did not contradict
the predictions of the Standard Model.
Lesko:
But the idea that we have mixing with neutrinos is
brand new and requires that we do not an overhaul
but an enhancement or an increasing inclusion of additional
factors into the Standard Model. So it really is a
fundamental change that has to be accommodated.
Narrator:
For Science Today, I'm Larissa Branin.
E.
Learning to Fight Fire with Fire
Narrator:
This is Science Today. For the last one hundred years,
the United States pursued a policy of fighting wildfires
through fire suppression. Scott Stephens, a professor
of fire science at the University of California, Berkeley,
explains the dangers of a zero tolerance policy for
wildfires.
Stephens:
But in many areas in the West or in places that
had frequent fires, you stop fires there for a hundred
years, dramatic changes occur, now they're very hazardous
and they can burn really outside their range of normal
variation.
Narrator:
To deal with this problem the Forest Service has started
using controlled burns, or fighting fire with fire,
to clear out dangerously thick forests. Controlled
burns from last year are credited with slowing some
the recent blazes in Colorado and Arizona.
Stephens:
So we're on a trajectory to do more fire use in the
United States. When you look though, at the historical
amount of fire that used to occur in many of our ecosystems
in western United States, it was really millions and
millions of acres. We're going to have to get creative
because fire use alone with urbanization, air quality
and other constraints, fire alone is not going to
be the only answer we can use.
Narrator:
For
Science Today, I'm Larissa Branin.
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