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A.
Geologists Date Glaciers that once Existed Near
Los Angeles
Narrator:
This is Science Today. Small glaciers once existed
near Los Angeles as recently as the present interglacial
period, which began several thousand years ago.
Lewis Owen, a professor of geology at the University
of California, Riverside, says their discovery has
implications for understanding climate changes.
Owen:
What we're trying to do is to quantify rates
of climate change essentially and we do that by
looking at geologic record. By understanding the
past we can try and predict what's happening in
the future.
Narrator:
Owen says that five years ago the best you could
do was to guess the dates of glaciers, but today
using a technology called 'cosmogenic radionuclide
dating' things have changed. This technology can
date moraines, which are the accumulated earth and
stones created by glaciers.
Owen:
Our work has really provided the first set of dates
and timing of glaciation right at the southwestern
part of North America and prior to that, we could
only guess at the age of those moraines at that
time and the age of the fluctuations of glaciers
because we didn't have these numerical dating techniques.
Narrator:
For Science Today, I'm Larissa Branin.
B.
Are Attitudes about Food Irradiation Changing?
Narrator:
This is Science Today. Food irradiation is a process
in which a product is exposed to a small, carefully
measured burst of an electron beam to kill bacteria
and parasites that would otherwise cause foodborne
disease. But over it's long history, irradiated food
has never been a popular sell among the American public.
But University of California, Davis food marketing
expert Christine Bruhn, says consumer attitudes about
food safety are changing, due to an increase in food
recall incidents.
Bruhn:
Within California itself, we have had some years where
as many as 500 kids had foodborne illness traced to
the school lunch program. Now, the data doesn't show
exactly what that food source was, but that's not
acceptable.
Narrator:
Bruhn says, consumers' early rejection of irradiation
was largely based on fear and misunderstanding.
Bruhn:
People, some say you don't need it and it's going
to be a hazard - time has shown irradiation saves
lives because it does destroy those harmful bacteria
before you're bringing it into your home.
Narrator:
For
Science Today, I'm Larissa Branin.
C.
To
Reap the Mood-Enhancing Benefits of Exercise, Don't
Stop
Narrator:
This is Science Today. A study of an elderly population
of men and women has found that exercise has no long-lasting
effects on mood if it is stopped. Donna Kritz-Silverstein
who led the University of California, San Diego study,
says they based their findings on a large group of
individuals who were studied in the 1980s and again,
in the 1990s.
Kritz-Silverstein:
Those who exercised at both points in time had the
lowest depressed mood scores and those who had not
exercised at the earlier visit, but began exercising
or exercising at the later visit, they had scores
that were comparable to those who had exercised at
both visits.
Narrator:
But Kritz-Silverstein found that people who had exercised
earlier and then stopped were much more comparable
to the people who were not exercising during either
visit.
Kritz-Silverstein:
It shows that exercise does have beneficial effects
for mood, even among individual who are not depressed
and that it's important to continually maintain this
exercise, because once you stop, it doesn't seem like
there's any continuous beneficial effect.
Narrator:
For Science Today, I'm Larissa Branin.
D.
How Have New Certification Rules Affected the Organic
Food Industry?
Narrator:
This is Science Today. It's been over a year since
the U.S. Government imposed strict new certification
rules on all organic farmers grossing over five thousand
dollars in sales. The question is - how has this certification
process affected the nation's organic industry? University
of California agricultural economist, Karen Klonsky,
says some people dropped the organic designation in
favor of natural or pesticide-free labels.
Klonsky:
In our previous research we saw that most growers
grossing over about 250 thousand dollars a year, were
already certified. But that there were a large number
of growers between five thousand and 250 thousand
dollars who were not certified, so there was going
to be this tremendous rush to become certified. But
that hasn't been the case.
Narrator:
Klonsky says literally the Million Dollar question
is what percentage of the total pie can organic take
up?
Klonsky:
And this will depend tremendously on conventional
grocery store chains - how much shelf space they want
to devote to organic.
Narrator:
For Science Today, I'm Larissa Branin.
E.
How to Deal with Chronic Stress
Narrator:
This is Science Today. Most people have experienced
acute stress in their life - such as being in a car
accident. This type of stress causes stress hormones
to secrete for a brief period. But for those of us
who suffer from long-term stress, or chronic stress,
the system that stops the secretions fails. Mary Dallman,
a physiology professor at the University of California,
San Francisco says people who suffer from chronic
stress should start thinking objectively.
Dallman:
I think part of the problem is that people get so
caught up in what's wrong that they don't pull back
and try to think objectively of what's wrong and see
what they can do about each thing.
Narrator:
Chronic
stress can be self-treated with activities such as
exercise, yoga, sex, and baths-all of which stimulate
neurochemicals that activate regions of the brain
that induce pleasure.
Dallman:
Just to get apart so that you can get an objective
look at what's going on in your life and see if you
can't change some of the things that are aversive.
Narrator:
For Science Today, I'm Larissa Branin.
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