Straight ahead on "Our World" ... stay in school and live longer ... nanotechnology and our food supply ... and Bill Gates warns of a shortage of scientists ...

GATES: Today our university computer science and engineering programs include large numbers of foreign students. But our current immigration policies make it increasingly difficult for these students to remain in the United States.

Those stories, future climate change clues from 10,000 years ago, and more. I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."


On Tuesday, government scientists released the results of a study of teenage girls indicating that one-quarter of them were infected with a sexually-transmitted disease, or STD. At that rate, some 3.2 million young American women between ages 14 and 19 are infected. Erika Celeste has more from the campus of Mississippi State University.

CELESTE: The people on the campus of Mississippi State University awoke to the same news heard around the country: a new study, the first of its kind by the U.S. Centers for Disease Control and Prevention (CDC) which examined the national prevalence of sexually transmitted diseases and infections among American teenage girls.

The study said twenty-six percent of female adolescents in the U.S. have at least one of four common STDs. That surprised this MSU senior, who wanted to remain anonymous.

GIRL: "Well that really does sound like a lot. The only thing I can think that would prevent that, I would think, would be abstinence until marriage and even then you don't know ?"

CELESTE: On the other hand, the study did not surprise the executive director of University Health Services, Dr. Robert Collins.

COLLINS: "You've got to realize that we have a sexually active young population. And the younger a woman is when she begins her sexual activity, the more likely she is to develop an STD because the cervix is not mature enough to defend itself from a lot of the STDs."

CELESTE: CDC researchers tracked the prevalence of HPV [human papilloma virus] or genital warts, Chlamydia, trichomoniasis, and herpes. The study found that African-American girls have the highest percent of STDs at 48 percent ? almost two and a half times the rate of their Caucasian and Mexican-American counterparts. That sounds fairly accurate to an African-American senior named Reeva.

REEVA: "The fact that is the girls may have it but they don't know they have it, and most of them don't want to know. It's as simple as that. They don't want to feel as though they can get an STI [sexually transmitted infection], which they can, because they are having unprotected sex. The majority of my high school was already pregnant, they were at least 16, with a child and working on another one."

CELESTE: The researchers found that about half of the 14-19 year olds in the study said that they had had sex, and among this group 40 percent were infected with an STD.

Unlike Reeva, who grew up in the South, Nicholas went to high school in the Midwest. But he says he saw the same reluctance on the part of adults to talk about sexual responsibility.

NICHOLAS: "When I was in high school, I mean, nobody really in school was talking about [the need to] protect yourself while you're having sex. Nobody in the church [was]. The church should be talking about abstinence. I think that's a subject society looks over, you look at the glorified images of sex [in the media] and you know that they [teens] are having it, but they're not being trained."

CELESTE: The Bush administration policies promote abstinence, but public health officials note that some young people are going to have sex anyway.

MSU's Dr. Collins says while it may be uncomfortable, the bottom line is parents need to discuss sexual responsibility with their children, and he says it's never too soon to begin that discussion.

COLLINS: "The one person that a child will listen to is their parents. Even though [a parent] may not think [their child] is listening, they will hear them."

CELESTE: The health effects of STDs for women can range from infertility to cervical cancer. CDC officials say screening, vaccination, and other prevention strategies for sexually-active women are among the nation's highest public health priorities.

For Our World, I'm Erika Celeste in Starkville Mississippi.


Why do some people live longer, healthier lives than others? Is it diet? Exercise? Where you live? Your family? Well, all of those, and more. And now, as we hear from health reporter Rose Hoban, new research indicates it may be linked to how much time you spent in school.

HOBAN: Harvard University health policy researcher Ellen Meara says scholars have found some clues as to why some groups of people have more or less disease than others.

She says one important factor in people's health is the amount of education they have. In her most recent paper, Meara and her colleagues examined data from several decades.

MEARA: "We looked at life expectancy at age 25. How many additional years can you expect to live if you arrive at age 25 and your education has stopped at high school, or sooner? Versus how many years can you expect to live if you've reached age 25 and you've gone on to at least some college?."

HOBAN: Meara says they found that in 1990, a 25-year-old who only had some secondary school could expect to live for a total of 75 years. In 2000, a 25-year-old with some secondary education could also expect to live to the age of 75.

MEARA: "In contrast, for a better educated 25-year-old, they could expect to live to the age of 80 in 1990, and looking at somebody with a similar education level in the year 2000, they could expect to live to be more than 81 years."

HOBAN: So, not only do better-educated people live longer to begin with, but over just ten years, more-educated people made gains in the length of their lives. Meanwhile, the life expectancy didn't change for less educated people.

Meara says some of these gains can be explained. For example, researchers know that people who are more educated are more likely to quit smoking cigarettes, or not start at all.

MEARA: "I think it's a reminder not to be complacent, that just because a population overall appears to be getting healthier, it doesn't always mean that those advantages that many people have enjoyed really extend into all parts of the population. And I think that's something to really pay attention to, regardless of whether you live in the U.S. or elsewhere."

HOBAN: Meara points out that education often determines income: people with more education frequently make more money. This makes them better able to access health care.

But the data on income do not show that people who make more money are automatically healthier. Meara says education is key. People need to be educated in order to take advantage of opportunities for better health.

Her research appears in the journal Health Affairs. I'm Rose Hoban.


A major environmental group is out with a new report this week warning of the danger posed by the use of nanotechnology in food.

In a 62-page report, Friends of the Earth says nanoparticles ? measured in billionths of a meter ? are starting to enter the food chain as scientists discover useful properties of this new class of materials.

ILLUMINATO: "There's a potential for potent nutritional additives, stronger flavorings and colorings, or anti-bacterial food packaging. However, there's also a rapidly-expanding body of science that demonstrates some of these nanomaterials now being used in foods introduce new risks for humans and the environment."

Ian Illuminato of Friends of the Earth told reporters that the risks of nanomaterials in the food chain are largely unknown, due to the fact that nanoscale materials are often very different from the same materials in their ordinary form.

ILLUMINATO: "So for example, with nano-gold, when it's at the nano-scale it's purple. So we have materials which are now in products and have all sorts of different kinds of characteristics that are nothing like the material that they come from. So we're really dealing with the whole new set of materials."

Friends of the Earth says some 100 food and food-related products already on the market use nanomaterials, and there is little regulatory oversight.

Illuminato said that it is not absolutely certain that nano-foods are harmful, but that because preliminary studies indicate a possible risk, the group is urging a moratorium on the use of nanoparticles in food until their safety is confirmed.

ILLUMINATO: "We definitely think that these products, as a first choice, should be taken off the market, that people shouldn't eat things, which we're not sure are healthy for humans to consume."

The group's study was received cautiously by the Project on Emerging Nanotechnologies of the Woodrow Wilson Center in Washington, a scholarly research organization financed by both government and private funds.

"The report is actually surprisingly sophisticated and raises a number of important questions which I think need to be addressed."

Dr. Andrew Maynard is chief science advisor to the Project on Emerging Nanotechnologies.

"Having said that, I think in parts of the report they take the available data on nanomaterial toxicity too far, and really a number of the conclusions that are drawn I don't think are justified from the science."

Maynard says Friends of the Earth appears to be taking a "zero-tolerance" approach to nanomaterials.

MAYNARD: "They cite a number of studies which are valid studies, but what they fail to link is the amount of material which is going to cause harm in humans or in the environment. And simply because a study shows that something is toxic doesn't necessarily mean it's going to be harmful. You also have to equate that with how much of the stuff is going to cause harm."

Andrew Maynard agreed with the Friends of the Earth report in its call for better labeling of products containing nanomaterials, to help consumers make informed choices.

In the meantime, products that take advantage of the novel properties of nanomaterials continue to enter the market, largely without coherent scrutiny by government health and safety agencies.


Time again for our Website of the Week, when we showcase interesting and innovative online destinations.

This week, it's a website targeted without apology at computer geeks, but full of news that everyone who uses or is affected by technology may find interesting.

MALDA: "Our catchphrase is 'news for nerds, stuff that matters.' It's basically a place where geeks go and congregate and spend their time and talk about Linux, open source, iPhones, technology, the things that government might be doing to influence our ability to use gadgets and technology, Internet culture, that sort of thing."

Rob Malda is creator of, a website full of technology news and, equally importantly, conversation about the new developments in the world of high tech. That sense of community ? where one news item can spark hundreds of comments ? is a basic part of what Slashdot is.

MALDA: "We like to compare Slashdot a little bit more to a pub than to a newspaper because we're really an opinionated bunch of curmudgeonly guys really discussing the issues."

Slashdot has been around for about a decade, and while most visitors are from North America, Malda says as many as one in four is from outside the U.S.

In recent days Slashdot readers could have learned about the newest beta release of the popular Firefox web browser, hacking a cardiac pacemaker, and new standards for aircraft flight recorders.

Most of the stories are submitted by readers, who also get to vote on each others' submissions, though Slashdot's editors do have the final word.

MALDA: "Our readers submit hundreds of stories to us every day, and we're sort of picking and choosing from them. Our readers are welcome to be a part of that process. They can vote up and down stories [in the 'firehose' section of the site], but at the end of the day our stories are selected by a group of biased editors, and not necessarily by the whims of a mob."

Rob Malda of, sounding a little tongue-in-cheek there. News for nerds, stuff that matters as they say, at, or get the link from our site,

MUSIC: Jean-Michel Jarre ? "Computer Week End"

News for nerds ... and everyone else ... on VOA's science and technology magazine, Our World. I'm Art Chimes in Washington.


Technology and innovation met education, immigration and the economy on Capitol Hill this week, as Bill Gates spent a couple of hours with the House of Representatives Science Committee.

Gates, of course, is the founder of software giant Microsoft and the Bill and Melinda Gates Foundation, which focuses on international health and education programs. He's also one of the wealthiest people in the world, and a pretty smart guy, so when Bill Gates talks, people listen. He told legislators on Wednesday that America's global preeminence in science and technology is at risk.

GATES: "There are many reasons for this, but two stand out. First, U.S. companies face a severe shortfall of scientists and engineers with expertise to develop the next generation of breakthroughs. Second, we don't invest enough as a nation in the basic research needed to drive long-term innovation. If we don't reverse these trends, our competitive advantage will erode. It starts with education. Today, graduation rates for our high school students and their level of achievement in math and science rank at the bottom among industrialized nations. If the problem with high schools is one of quality, the issue at our universities is one of quantity. Our higher education system doesn't produce enough top scientists and engineers to meet the need of the U.S. economy. Today our university computer science and engineering programs include large numbers of foreign students. But our current immigration policies make it increasingly difficult for these students to remain in the United States. It makes no sense to educate people in our universities and then insist that they return home."

Bill Gates told the members of Congress that addressing these concerns will take commitment, leadership, and partnership among government, corporate, and non-profit groups.


A new study of climate and vegetation more than 10,000 years ago may offer a clue to what's in store for much of the Arctic in decades to come.

The study comes from Montana State University, where Philip Higuera ((hy-GERR-uh)) is based. To delve into the climate history of the northern tundra, he and his colleagues traveled to a remote area north of the Arctic Circle in Alaska, and dug deep into the sediment at the bottom of lakes that have been around since the end of the last ice age.

HIGUERA: "So they've been around for about 15,000 years. We collect cores from the bottom of those lakes. And then we slice up those cores into very fine intervals and in each one of those intervals we can look at things like pollen to reconstruct the vegetation, and we can look at pieces of charcoal to reconstruct when fires burned."

Higuera says fires were much more frequent 10-15,000 years ago than they are in tundra regions today - in fact, the land was burned at about the rate seen in today's northern boreal forests, which are full of pine trees, not the knee-high shrubbery of today's tundra.

HIGUERA: "We're inferring that the density of shrubs was greater than we see on the modern [tundra] landscape. So that means shrubs were taller ? up to your waist or up to your head as opposed to below your knee, like you'd find on the modern landscape. So an increase in biomass, shrub biomass, provided fuels to burn, and then the other characteristic that was important back then was that climate was drier than present, which increases the flammability."

In other studies, scientists have observed that the vegetation in tundra areas is changing today - there is more biomass in the form of bigger and denser shrubs, likely as a result of global warming. That vegetation stores carbon, which is released in the form of carbon dioxide ? a greenhouse gas ? when the plant dies or is consumed by fire.

HIGUERA: "Combine the increase in temperatures with the change in the nature of the vegetation, the change in the fuels, and that alone would lead you to predict that the probability of fire would increase. The important thing that our study provides is kind of a precedent of, hey!, this has happened in the past and actually tundra vegetation can sustain fire regimes that are equivalent to what we see in the modern boreal forest."

In addition to the direct release of greenhouse gases, fires in the arctic could contribute to global warming through what scientists call feedback loops. For example, Higuera says, scientists have measured the melting of permafrost after fires in the tundra.

HIGUERA: "And as you'd expect, permafrost melts because of the fire and then after the fire [it melts] because you have a black surface exposed to sunlight, which absorbs more energy. So certainly links between fire and melting permafrost are an important thing, and we mention that briefly in the paper."

Another part of the 'loop' is the decaying plant and animal material trapped in the permafrost. It produces methane gas, which can be released when the permafrost melts. Methane is an even more powerful greenhouse gas than carbon dioxide.

Higuera's study on Arctic tundra is published online in the journal PLoS One.


Climate change may affect the natural environment in the Arctic, where there are scarcely any people. But it's also likely to have a big impact where people do live and work.

An expert group organized by the National Research Council, part of the National Academy of Sciences, this week released a study of how climate change could affect transportation.

Although the report focuses on the impact of global warming on the U.S. transportation infrastructure, many of the same issues identified by the scientists and planners are likely to crop up wherever people and vehicles are on the move. Rosanne Skirble has our report.

SKIRBLE: One hundred thousand kilometers of U.S. coastal highways are occasionally flooded. More severe weather could make these roads impassable, a major problem since many of them are also designated as public evacuation routes during natural disasters. Henry Schwartz, civil engineer and chairman of the National Research Council committee that wrote the report says the chaos caused by such transport bottlenecks could be costly in human and economic terms

SCHWARTZ: "We believe strongly that the time is now for the transportation community to begin to understand the implications of and address climate change as an important consideration in developing and maintaining the transportation that works in our country."

SKIRBLE: The report authors affirm the findings of the Intergovernmental Panel on Climate Change, the United Nations group which has produced a series of assessments that say global warming is real and caused by human activities.

SCHWARTZ: "Our committee accepted this position and then asked how might global warming impact transportation."

SKIRBLE: The climate threats identified in report include increases in very hot days and heat waves, higher Arctic temperatures, sea level rise, and an increase in more intense precipitation and more severe hurricanes.

The U.S. transportation system was built for local weather and climate conditions based on conventional climate models and forecasts. Schwartz says those predictions may be less reliable, especially in light of the weather and climate extremes in recent decades.

SCHWARTZ: "The curve has kicked up. The extremes are going to be higher. So we have to adjust. The one in 100 year storm may become the one in 50 year storm. What is the proper level to design all of our infrastructure?"

SKIRBLE: Local managers face day-to-day problems. Schwartz says little attention has been paid to global warming and its impact on transportation.

SCHWARTZ: "Our first recommendation is that the affected governmental agencies, and owners both public and private, need to begin to inventory what particular infrastructure areas in light of potential climate change basically to understand what assets are at risk."

SKIRBLE: Just such an inventory will be getting underway in the northeastern state of Massachusetts later this year. Luisa Paiewonsky is commissioner of the Massachusetts Highway Department.

PAIEWONSKY: "Inventorying our critical low-lying and coastal highway infrastructure to assess the vulnerability of it to events caused by climate."

SKIRBLE: The National Research Council report also calls for the creation of a clearinghouse for information on climate science and transportation, better communications among transport agencies, and establishment of new engineering standards. Schwartz says the local, state and federal government and the private sector must work together to adapt.

SCHWARTZ: "Our final recommendation does suggest that incentives be incorporated into federal and state legislation that would encourage this, but we are not depending, our recommendations don't depend on federal legislation."

SKIRBLE: Schwartz says taking actions to prepare for climate change now could help avoid costly future disruptions and even more costly repair s to the nation's vital transportation network. I'm Rosanne Skirble.

You can download the full report from the National Academy website, and we'll have a link on our site,


MUSIC: "Our World" theme

That's our show for this week. If you'd like to to get in touch, email us at Or use the postal address ?

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Faith Lapidus edited the show. Eva Nenicka is the technical director. Thanks to Rob Sivak for filling in last week. And this is Art Chimes, inviting you to join us online at or on your radio next Saturday and Sunday as we check out the latest in science and technology ... in Our World.