Photo of man in Uzbekistan by Nabikhan Utarbekov via Flickr Creative Commons.

On Monday, a baby will be born somewhere and demographers will proclaim that the world's population has reached 7 billion. That's good news and bad news, according to a United Nations Population Fund report released Wednesday.

People are living longer and leading healthier lives. But there are plenty of worries that the globe may not have enough food and water to sustain rapidly growing populations.

The date itself, Monday, is a symbolic one, extrapolated from census data, surveys and population registers, but the implications are real, the United Nations says. (Read the U.N. Population Fund's full report.)

Even though fertility rates are lower than in the past, the population is still expected to rise naturally through what is known as population momentum, said Richard Kollodge, editor of the U.N. report.

Each incremental growth of a billion takes less and less time. Those increases are attributable to positive factors, said Kollodge. "People are healthier; they're living longer. Child mortality is down. This relatively recent surge in population growth for the most part can be seen as good news."

View past and projected global population growth:

In South Asia and Africa, population growth is most prolific. Many countries in sub-Saharan Africa have high population growth rates and high fertility rates but low economic growth rates, which can be problematic, said Kollodge. "The population is growing faster than the government's ability to meet the need for services, education and health. Economic growth isn't keeping up with population growth," so the countries become poorer.

In the middle-income countries -- mainly in Latin America -- population growth has stabilized, he said. But they still face challenges of rapid urbanization and people moving in and out of the countries quickly, which governments are trying to manage.

Asia's population, currently at 4.2 billion, is expected to remain the highest during the 21st century, according to the Population Division of the United Nations Department of Economic and Social Affairs. Photo of Dotombori, the entertainment district of Osaka, Japan, by photholic.com via Flickr Creative Commons.

But even while the world's population is growing, in some wealthy industrialized countries -- including several European nations and Japan -- populations are shrinking because fertility rates are not high enough to replace population losses. That means there aren't enough young people entering the work force to sustain economic growth and pension systems are receiving less funding to support the elderly, said Kollodge.

"They're also dealing with issues of migration and asking questions of, 'If our populations are shrinking, should we invite more people from other countries to come in and meet labor shortages?'" he said.

The U.N. report makes some recommendations for addressing population challenges, such as giving women access to reproductive health services, education and good jobs. "When women are educated and healthy, they choose to have smaller families, and when they do have smaller families, their children end up being healthier," said Kollodge.

Africa's population is expected to more than triple, from 1 billion in 2011 to 3.6 billion in 2100, according to the United Nations. Photo by Novartis AG via Flickr Creative Commons.

The report also recommends investing in youth. About 1.8 billion young people, between the ages of 10 and 24, live around the world now, he said. "That's the largest youth cohort in human history. So we're advocating for making sure that all these young people have education, that they're all in good health and free of HIV, that they have opportunities, that they are empowered to drive our future economies."

But all of that takes money. Sexual reproductive health initiatives alone -- an action plan was proposed at a 1994 population summit of 179 countries -- would cost $68 billion in 2011. Countries agreed to pay $34 billion and international donors $10.8 billion, but that left a nearly $25 billion gap, Kollodge said.

The elderly also are a growing segment of the population, raising the challenge of who will take care of them and how social security programs will be funded. "But also look at the flip side -- let's not create a world where the elderly are only dependent," but are active and independent and continuing to contribute to their communities, he said.

"Those are big challenges and it's better to plan for them now because the world is only going to grow older in the years ahead," he said.

And depending on fertility rates, the next milestone birthday -- when the world hits 8 billion people -- might be as soon as 2025.

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Special correspondent Steve Sapienza reported in March on the NewsHour on a new way to get water to poor pockets in Bangladesh:

In another report in August, special correspondent Fred de Sam Lazaro looked at the declining fertility rate among women in Brazil:

Lazaro described the looming water crisis in India's New Delhi in this December report.

View all of our World coverage and follow us on Twitter.

Scientists have identified the cause of a vicious disease devastating the northeastern U.S. bat population. Photo by Jonathan Mays, Wildlife Biologist, Maine Department of Inland Fisheries and Wildlife.

A fungus known as Geomyces destructans is indeed responsible for the dusting of white across bat noses and wings that has wiped out entire populations of the flying mammals, new research shows. By purposefully infecting healthy bats with the fungus -- and confirming that seemingly healthy "control" bats from the same population did not get sick from a prior but hidden fungal infection -- microbiologist David Blehert of the U.S. Geological Survey and his colleagues showed in a paper published online October 26 in Nature that G. destructans is in fact responsible for the disease known as white-nose syndrome (WNS), which has devastated bat populations across the northeastern U.S., killing an estimated one million of the animals. (Scientific American is part of Nature Publishing Group.)

"It is specifically during hibernation that bats are infected with this fungus," Blehert notes. "The greatest damage it does to bats is to wing membranes."

Such membranes, in addition to enabling flight, help control physiological functions such as water retention and blood flow, and even "release CO2 when the respiratory rate is just a couple of breaths per minute," Blehert says. At the same time, it is not clear why a skin infection with G. destructans would prove directly lethal to the animals -- the bats in this controlled experiment had not died from the disease by the time the experiment ended after 102 days. Nor had the fungus invaded the bats' vital organs, the researchers found.

In addition, it appears that G. destructans has been a part of the European cave-scape for some time and it has been isolated from cave walls there as well as from bats roosting in those caves. Thus far, however, the fungus has not proved lethal for those species. "It could be that European bats have evolved over a longer period of time and are immune or have a different way of coping with the fungus during hibernation," says mycologist Vishnu Chaturvedi of the New York State Department of Health, who is also studying the fungus and disease, which he calls geomycosis, but was not involved in this study. "Or the fungus in the U.S. has subtle variations that we have not even started looking at."

The core problem seems to be that G. destructans is depleting the fat layers -- and thus the body mass -- of very small North American bat species, such as the little brown bats used in this experiment. Blehert speculates that the lack of mass mortality in Europe may derive from the fact that European bat species are generally larger in size or the fact that they tend to hibernate in much smaller groups. "In the northeastern U.S. there are many very large hibernaculums, with upwards of 1,000 bats," Blehert notes. "The bat is providing food for the fungus and serving as an amplification host."

In fact, Blehert's experiments show that bats are quite effective at spreading the destructive fungal disease to their neighbors. "Bats are very good agents of transmission of the disease," Chaturvedi says. And that--plus the European analysis--may suggest that G. destructans is an invasive species, according to Blehert, which possibly traveled to the U.S. on a European who visited a public cavern in New York State. WNS was first observed in a wild cave connected to that commercial cave complex near Albany, N.Y. Chaturvedi's work has shown that G. destructans in North America is genetically similar wherever it is found.

There is hope for the bats. Another experiment by Blehert and his colleagues showed that bats artificially removed from hibernation, put in a warm environment, and provided with food and water could recover from WNS. "Bats can rapidly clear the infection in just a matter of weeks," Blehert says. It may be that G. destructans relies on the turning down or shutting off of the bat's immune system during hibernation -- as is common to most hibernating mammals -- to wreak havoc. The fungus seems to grow best at cold temperatures between 4 and 15 degrees Celsius. "It could be that hibernation is the Achilles' heel that is predisposing bats to G. destructans infection," Blehert adds.

But keeping hundreds of thousands of bats from hibernating is hardly plausible. "You can't just wake them up and shoo them out," Blehert notes, nor is it possible to feed them in mass quantities to restore fat levels. Restricting human access to caves where susceptible bats hibernate -- as has been done by the U.S. Fish and Wildlife Service -- and following decontamination protocols when such access is necessary will at least reduce the risk of humans further spreading the disease, which has now spread to infect bats in 11 states and Canada. "Segregating healthy animals from diseased ones to the extent possible does seem to be able to control this infection," Chaturvedi adds.

Regardless, the G. destructans epidemic is just another example of fungal disease on the march: Chytridiomycosis is wiping out amphibians worldwide and fungi may be playing a role in the colony-collapse disorder plaguing honeybees. One effort to protect frogs from this fungal plague are so-called amphibian arks, where small populations are taken into captivity to ensure their survival. That approach may become necessary for certain endangered bat species as well to protect them from the white-nose syndrome caused by G. destructans. As Blehert and his colleagues wrote: "Fungal pathogens have the unique capacity to drive host populations to extinction because of their ability to survive in host-free environments."

This article is reproduced with permission from Scientific American. It was first published on October 26. Find the original story here.

On Oct. 23, a German research satellite re-entered the earth's atmosphere and plunged into the northeast Indian Ocean's Bay of Bengal.

This event came less than two months after a report, conducted by the National Research Council and sponsored by NASA, warned that the amount of "space junk" orbiting Earth has reached a tipping point.

Donald Kessler, chair of the committee that published the report and former head of NASA's orbital debris research program, has been warning of the risks of space junk since 1978. We asked him about the ins and outs of orbital debris: how much is out there, what does it look like, what happens when these objects collide and what danger do they pose for future space travel and for us on Earth?

Kessler also discusses a troubling scenario he has predicted, which has since been dubbed the "Kessler syndrome." It describes a situation in which cascades of collisions among objects in low-Earth orbit build up debris, making space travel increasingly difficult.

Find more coverage on our science page.

A satellite designed to study the Earth's weather and climate launched into space aboard a Delta II rocket early Friday morning. It lifted off from California's Vandenberg Air Force through clear skies and ideal weather.

Watch video of the launch here:

The spacecraft is called NPP, short for the wordier National Polar-orbiting Operational Environmental Satellite System Preparatory Project. A little bigger than a Jeep, the two-ton satellite will orbit 512 miles above Earth, joining a fleet of other climate-watching satellites like NASA's Terra, Aqua and Aura, which have already aged beyond their expected lifetimes.

But NPP is more advanced than its brethren -- equipped with five instruments to measure ozone, dust particles in the atmosphere, sea surface temperatures, atmospheric pressure and solar radiation, among other things. It will also monitor wildfires, ice movement and clouds and land changes on Earth. Four of the instruments are brand new, more capable of taking precise measurements than the satellites already in orbit.

"It will do quite a sweep of things," said NASA spokesman Steve Cole. "It will be useful for research and real-world applications, like forest fires. So it has real, current, immediate applications, as well as ongoing information on the climate. We're getting a two-fer on a lot of these measurements. It can do long-term science and be very useful day-to-day."

And much of NPP's value is that it's not all that different than the other weather-forecasting and climate-modeling satellites, Cole added. It will add to data already being measured by older satellites.

"Data gets more valuable as it gets older," he said. "As you have a longer and longer record, you can really understand better what's going on."

It was a long road to Friday's liftoff. The satellite was originally scheduled to launch in 2006, but development of the instruments took longer than planned.

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Author Walter Isaacson tells the story of Apple's late co-founder in a new biography simply titled "Steve Jobs." Jeffrey Brown and Isaacson discuss Jobs' personality, legacy and how his love of the arts shaped his views on innovation.

JEFFREY BROWN: When Steve Jobs died earlier this month of pancreatic cancer, he was lionized as one of the era's greatest innovators, a man of enormous influence who co-founded Apple in his 20s, and whose products and designs revolutionized personal computing, cell phones, the music business, film animation, tablet computing, digital publishing and more.

The story of the man himself is now told in a new biography titled simply "Steve Jobs." Its author is Walter Isaacson, longtime journalist and author of previous biographies on Albert Einstein and Benjamin Franklin, and joins me now.

Welcome to you.

WALTER ISAACSON, "Steve Jobs": Good to be here again.

JEFFREY BROWN: You write at the end -- I'm going to start at the end of the book, because it's kind of interesting to go to what -- the thing you say near the end.

WALTER ISAACSON: Most people never get there.

(LAUGHTER)

JEFFREY BROWN: You say: "Was he smart? No, not exceptionally. Instead, he was a genius."

Now, what does that mean?

WALTER ISAACSON: That means that he could connect creativity to problems. He wasn't just an analytic thinker.

He told me that when he came back from India, where he went as a dropout from college to seek enlightenment, he learned the power of intuition. And I think that genius comes not just from having great mental processing power. It comes from being able to, as Steve Jobs' ad said, think different. And so that intuition, where you can make these creative, imaginative leaps. That was his particular strength, was tying that artistry to engineering.

JEFFREY BROWN: When you go back to the story to see where all this came from, he was adopted, right? And there's -- a number of people tell you about how that somehow shaped his character, the sense of abandonment. He, though, said to you -- he insisted, no. He felt special.

WALTER ISAACSON: He said no.

Yes, he said his parents, the people that adopted him, his real parents, said, you were chosen, you were special. And he looked at himself that way. But he also looked upon his life as a journey and that journey was always to find himself, seek enlightenment, understand how he fit in.

And I think he felt he didn't fit in, in the normal way because he was put in a place where he wasn't born, and he felt, OK, I have to sort of be part of that journey. He always loved to use the maxim that Buddhist phrase of the journey is the reward.

And I think that notion of being a seeker, somebody who never felt totally fulfilled, but was always passionate about the search, that comes from the background, probably.

JEFFREY BROWN: But he studied Zen, but didn't have a Zen calm, right?

WALTER ISAACSON: Right.

JEFFREY BROWN: He sought, but he -- and he had this feeling of being special, but it had a negative side, too. I don't have to play by the rules. I can get around people. And he was mean to people.

WALTER ISAACSON: Right.

Not playing by the rules, not seeing things conventionally, that's the heart of who he is, and he does it in small ways of everyday rebellion just almost to assert who he is, like not putting a license plate on his car. But he also does it in other ways, which is to say, no, we're going to do the impossible. And he makes people do that.

Yes, the arc of the narrative of the book is a guy who can be pretty rough and mean on people, but, by the end, by the end of his career, he has proven that they can do the impossible, and he has gathered probably the most loyal team of eight players of any business in America.

JEFFREY BROWN: Now, what explains that?

WALTER ISAACSON: Well, he was inspiring.

JEFFREY BROWN: He's inspiring.

WALTER ISAACSON: Yes.

JEFFREY BROWN: And you describe a certain -- there's a charisma.

WALTER ISAACSON: Not only a charisma, but if you are tough on people and you say brutal honesty is the price of admission to this room, and then you push them through your magical thinking to do things they thought were impossible, that creates a team loyalty.

And I think if you just look at, oh, he used to occasionally snap at people, I -- that -- this is the narrative of the book.

JEFFREY BROWN: Yes.

We talk so much about the enormous success and impact. But maybe take us to a moment that -- where that wasn't apparent, right? There was failure, when he was pushed out of his own company and things didn't look very good for him.

WALTER ISAACSON: That's certainly part of the narrative, which is he creates an insanely great machine, as he calls it, the Macintosh.

It's not -- it doesn't do all that well by 1985 in the marketplace. And his personality and that of the much smoother John Sculley, who is a very polite, gentle soul, clash, and in the end, he gets ousted from the company he creates. It's almost like a Shakespearian drama.

But the real failure and success comes in the period people don't know much about, when he's running NeXT Computers, and he's indulging all of his artistic instincts. He wants the angle to be exactly 90 degrees, even though it's harder to mold a machine like that. He wants it to be a perfect cube. He wants it to have the greatest logo. So he indulges every artistic instinct, and he hasn't yet learned, how do you tie art to sort of engineering and common sense so that he can make a product that can work in the marketplace?

So it's kind of a glorious market failure.

JEFFREY BROWN: Well, use -- that word failure, was there a moment where he sensed he might fail, where he feared failure?

WALTER ISAACSON: I think that he was upset because he was running Pixar and NeXT, and both were hemorrhaging money.

Now, what he ends up doing is creating a great operating system at NeXT that Apple then has to buy, because once he has left Apple, the people running the firm after a while can't even create a new operating system. So they end up having to buy NeXT for the UNIX-based kernel of the operating system, and they get Steve back.

Likewise, Pixar, it's computers were a little bit overdeveloped, the rendering computers that make 3-D graphics, but there was a guy there who was making beautiful animated shorts to show how the machines worked. Steve loved that artistry, and eventually Pixar becomes an animated digital movie company.

JEFFREY BROWN: Famous for this sense, the commitment, a maniacal sense of design, right?

WALTER ISAACSON: Oh, absolutely.

JEFFREY BROWN: And yet what you describe here -- and it's even -- you sort of see it on the cover here -- this sense of almost designing himself, I mean, studying his own stare, for example.

Did you come to think of him that way?

WALTER ISAACSON: Yes. He loved to be the maestro at product presentations. He invented many, many things, but one of the things he invented was this amazing unveiling of products, where the heavens part and the lights shine down and the choir sings hallelujah, and suddenly there's an iPod in his pocket or a Macintosh speaking on stage.

And that was part of his showmanship. But the showmanship was able to connect products to us emotionally, just as the design of the product was. So I think it was all part and parcel of his success.

JEFFREY BROWN: Do you think there is a sense -- I mean, after all, we're talking about products, right? Is there a sense of -- a danger, in a sense, of over glorifying the man? I mean, I was thinking, you wrote a biography of Einstein.

WALTER ISAACSON: Yes, right.

JEFFREY BROWN: Theory of relativity.

WALTER ISAACSON: Right.

JEFFREY BROWN: Now, the iPod is not the theory of relativity.

WALTER ISAACSON: Right. Right.

And Steve is a genius, but not in the same quantum orbit as Einstein.

JEFFREY BROWN: Right.

WALTER ISAACSON: And, yes, if we're so much making fetishes of our little iPods and iPhones, it's probably not the best thing.

But it's a lot better than making heroes out of people creating complex financial instruments that are causing the housing market to collapse or Greece to default. At least he's creating products that combined art and technology to make something that we really want and are useful. And having 1,000 songs in your pocket, that's not the worst thing in the world, you know? It's kind of nice.

JEFFREY BROWN: What about your -- I want to ask you about your experiences as a biographer in this case that we mentioned in Einstein.

You have written books about people -- well, several of them, at least, were long dead. Here, you were working with a man who was in the process of dying before your eyes. Did that change how you worked, what you wrote?

WALTER ISAACSON: Yes. Well, yes.

I actually -- because I was caught up in his magical thinking and his optimism, I thought he was going to stay a step ahead of the cancer. I mean, he always had new drugs. Every time the cancer sort of mutated around a particular drug he was using, they would find a new targeted therapy.

And so, in our last long meeting together, he said: "I won't read the book right away because I know there will be parts I won't like, and I don't want to get mad at you, but I will read it in a year."

So, I was actually writing a book not only of somebody who was wrestling with possible death, but also somebody I thought might be reading the book a year from now. So it was emotionally draining, yes.

JEFFREY BROWN: And, finally, the intersection of the humanities and the sciences, you mentioned that earlier, but that's one that grabbed me.

WALTER ISAACSON: Edwin Land, when he was starting out, the guy who started Polaroid, said the place to stand is the intersection of the humanities and technology.

JEFFREY BROWN: We tend to have a binary...

WALTER ISAACSON: And we do in this day and age, which is why I like writing about Ben Franklin and Einstein, because these are people who combined a love of science and a love of the humanities. This is what you get in Steve Jobs as well.

And that sort of explains to me a whole lot of it, that part of his mind that was artistic and poetic and that part of his mind that was a businessman and an engineer. In many people, that doesn't come together, especially in a lot of great technologists. They don't have the feel for art, but Steve did.

JEFFREY BROWN: All right. Walter Isaacson's new book is called "Steve Jobs."

Thanks so much.

WALTER ISAACSON: Thanks. Thanks for having me.

John Goodge of the University of Minnesota Duluth is studying rocks from the 2 percent of Antarctica that is not under ice in search of clues to the rest of the continent: how it formed and shaped over time, along with what's under the ice sheet. His team also hopes to learn more about the history of ancient continents, the health of the planet and the impacts of global climate change. Miles O'Brien reports for the National Science Foundation's* latest Science Nation.

*For the record, the National Science Foundation is an underwriter of the NewsHour.

Photo by Flickr user J. Paxon Reyes.

Chocolate may be the most sought-after treat among trick-or-treaters on Halloween, with little hands grasping for all of the milk- and dark-chocolate morsels they can collect, but the details of its taste and aroma profiles have long eluded scientists.

And new science is revealing why cocoa's potent sensual properties have been so difficult to pin down. A recent analysis found that the individual aroma molecules in roasted cacao beans (the primary ingredient of chocolate) can smell of everything from cooked cabbage to human sweat to raw beef fat. Together, more than 600 of these flavor compounds melt together in just the right combination to yield the taste and scent of what we all call chocolate, according to Peter Schieberle, a food chemist at Munich Technical University and director of the German Research Center for Food Chemistry, who presented the data at this year's meeting of the American Chemical Society in Denver.

Most of the molecules that comprise a food's aroma are volatile, which means they transform into gases easily at room temperature. These volatile compounds are inhaled along with the air we breathe, bringing them into contact with the 900-plus odorant receptors in the upper half of the nostril. In the early 1990s scientists Linda Buck and Richard Axel began the work that would show each odorant receptor recognized one particular compound and was linked to a specific olfactory neuron in the nostril. As a volatile aroma compound latches onto an odorant receptor, it triggers the firing of the olfactory neuron (Buck and Axel won the 2004 Nobel Prize in Physiology or Medicine for their discovery). Complex aromas form when multiple volatile compounds trigger their respective olfactory neurons at the same time. The brain identifies flavor by measuring how frequently the different neurons fire.

"By the time you put four chemicals together, your brain can no longer separate them into components. It forms a new, unified perception that you can't recognize as any of those individual aromas," says Gary Reineccius, a food scientist at the University of Minnesota.

Processed foods such as chocolate, beer and tea contain thousands of aroma compounds. This multiplicity of molecules creates a mosaic of odor in the brain as each individual molecule contributes a hint of scent to the final flavor. Just as our brains can often assemble a whole picture from seeing just a sketch of an image, Schieberle and colleagues found that humans can recognize chocolate aroma using only 25 of its 600-plus volatile compounds. Of these, many are also found in much less appetizing items, including cooked cabbage, raw beef fat and human sweat, which are in turn also composed of many different volatile compounds.

Even so, not one of these 25 key compounds can be pegged as a "chocolate" aroma. "The mixture smells completely different from the individual constituents," Schieberle says. "At the moment, there is no way to predict how the final mixture will smell."

Schieberle calls the study of individual aroma and flavor molecules "sensomics," which sifts through the countless potential aroma compounds for those molecules of particular importance to human taste and smell. Schieberle's work has identified which aroma compounds from roasted cacao beans could bind to odor receptors in humans. None of them, it turned out, smell anything at all like the sweet, rich scent we identify as chocolate.

To figure out exactly which molecules contributed to chocolate aroma, Schieberle and colleagues had to pick apart chocolate aroma one molecule at a time. First, the researchers identified those volatile compounds that would react with human odor receptors and were present at high enough levels to register in the brain, which yielded 25 different molecules. These molecules included 2- and 3-methylbutanoic acids (both produce a sweaty, rancid odor), dimethyl trisulfide (cooked cabbage) and 2-ethyl-3,5-dimethylpyrazine (potato chips). Then, they blended these rather un-chocolatey aroma molecules in different combinations and asked human study subjects to smell them. The blend that contained all of the 25 volatile aroma molecules could reliably fool the nose and brain into thinking it had smelled chocolate.

These 25 compounds are what Schieberle refers to as chocolate's chemical signature--those volatile compounds in chocolate that trigger human olfactory nerves in just the right combination "causing a signal in the brain to say 'this is chocolate,'" Schieberle says.

What we think of as "chocolate" smell is due in large part to the way in which the food is made--a process that includes both fermentation and roasting. Foods that are processed by fermentation, roasting or grilling such as wine, coffee and steak, respectively, generally contain the most aroma molecules. It is this process's conversion of otherwise odorless compounds into volatile aroma-bearing ones that helps explain this type of food's popularity. Natural, raw foods like fruits and vegetables also have an appealing aroma and taste, although their flavor profile is much simpler and usually dominated by one or two major molecules.

"That chemical really creates that flavor, and everything else kind of smoothes it and makes it pleasant," Reineccius says of these less complex foods. The combination of volatile aroma compounds as well as the sugars and salts that we taste during chewing combine to create flavor. "Some of our simpler flavors are strawberry and raspberry because they're just what nature happened to provide to keep itself living." The replication of these flavors by food chemists has previously been a process of trial and error.

The goal of his work, Schieberle says, is not to develop artificial chocolate flavorings. Rather, his goal is to find ways to tweak the cacao bean fermentation and roasting process to develop even better tasting chocolates. A recent discovery in his lab, made earlier this year, has taken a small step in this direction. Cacao beans processed in the so-called Dutch style, which adds alkali salt during roasting, have a milder, more pleasant flavor. After deconstructing the molecular makeup of this form of chocolate, the researchers knew that it contained molecules that had a pleasant "mouthfeel." And by adding a tiny bit of glucose to the cacao beans during the Dutch roasting process, Schieberle and colleagues, did not increase the sweetness of the final product, but instead created a more velvety mouthfeel in the final chocolate.

Better understanding chocolate's alluring aroma can also help with tasting technique. Let the chocolate dissolve on your tongue, Schieberle says, so that you can taste the full array of flavor compounds. As the chocolate melts in your mouth and you exhale, some of the volatile molecules will once again pass over your odor receptors, letting you get another whiff before the chocolate melts away.

This article is reproduced with permission from Scientific American. It was first published on October 31. Find the original story here.

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Stanford University biologist Nathan Wolfe is the founder and director of the Global Viral Forecasting Initiative and one of the world's more prominent virus hunters. Ray Suarez and Wolfe discuss his new book, "The Viral Storm: The Dawn of a New Pandemic Age," and new viruses emerging around the planet.

RAY SUAREZ: Finally tonight, the work of a scientist who spends his days tracking killer diseases.

A nondescript office building in downtown San Francisco may seem like an unlikely headquarters for one of the world's most prominent virus hunters, but it's where Stanford University biologist Nathan Wolfe has setup his war room to monitor and study new, and potentially deadly, viruses emerging around the globe.

NATHAN WOLFE, Global Viral Forecasting Initiative: It looks like we're going to release an Ebola finding on Monday.

RAY SUAREZ: The 41-year-old Wolfe is the founder and director of the Global Viral Forecasting Initiative. The mission sounds simple, but it's not -- detect pandemics and stop them before they spread.

How Wolfe and his team do that is a mix of high-tech detective work and old fashioned on-the-ground epidemiology research. And it's the subject of his new book, "The Viral Storm: The Dawn of a New Pandemic Age."

I sat down with Wolfe in his office.

NATHAN WOLFE: What we're looking at is this interface between human and animal populations. And we're trying to basically catch the really early stages of these pandemics, the moment at which, frankly, the pandemic is born or an epidemic is born.

And I always joke that if you go to you know Ocean Beach here in San Francisco, you will always see people running up and kissing their dogs. And that's a moment of cross-species transmission.  

ACTRESS: The average person touches their face three to five times every waking minute. In between, we're touching doorknobs, water fountains and each other.

RAY SUAREZ: A much more serious, but fictional, cross-species transmission was the focus of this summer's thriller "Contagion," in which millions died from a virus found in pigs and bats. Wolfe was a technical director on the film.

In the real world, viruses, the microscopic pathogens that invade and destroy host cells, have been jumping from animals to humans for ages. But with the huge increases in modern air traffic, an outbreak in one country quickly becomes a problem for the rest of the world.

NATHAN WOLFE: The challenge that we face right now is, we're so interconnected, that these viruses can spread in a day around the world. They can go from Central Africa, Southeast Asia. They can get to Tokyo. They can get to New York City. That's crystal-clear.

RAY SUAREZ: That global interconnectedness was highlighted in recent years with the SARS outbreak in 2003, and more recently with the H1N1 swine flu virus that started in Mexico. It quickly infected millions.

And then there's AIDS. At a 2009 TED Talk, Wolfe pointed out that millions of lives could potentially have been saved if the AIDS virus had been discovered when it first crossed from chimps to humans.

NATHAN WOLFE: This photo was taken before the Great Depression in Brazzaville, Congo. At this time, there were thousands of individuals, we think, that were infected with HIV. If this virus was in thousands of individuals at this point, why was it the case that it took us until 1984 to be able to discover this virus?

RAY SUAREZ: At his headquarters, Wolfe has assembled a team of savvy young computer gurus who comb the Internet, using sophisticated algorithms, to search for the digital clues that could indicate the outbreak of a disease.

NATHAN WOLFE: People, if they're sick, will search on a certain kind of symptoms, or at least a number of them will. So, at every moment, whether people are searching or tweeting or texting, people are increasingly sending off massive amounts of data that give us potential clues into what they're doing, what they're thinking.

RAY SUAREZ: But to really understand what viral threats are lurking out there, Wolfe has to get out of the office. Wolfe and his colleagues have been trekking through dense jungles in West Africa and parts of Asia, studying the close interactions between humans and the animals they hunt and eat.

The unhygienic conditions in which the bush meat or wild game is captured, prepared and eaten allows blood, bodily fluids and viruses to pass between hunter and prey.

NATHAN WOLFE: We have been working, say, in parts of Central Africa for over 10, 12 years just working with these populations year in and year out. And we're able to document this sometime, literally to watch these viruses as they're jumping over from animals into human populations.

We see novel retroviruses, so viruses that are in the same broad family as HIV, moving over into these hunters from animals that they have hunted.

RAY SUAREZ: Wolfe's team has collected more than 200,000 blood and tissue samples from animals, hunters and their families in Africa and Asia, field labs Wolfe describes as viral listening posts. Those samples are continuously analyzed by scientists for signs that new pathogens are crossing over to humans.

A lot of the places that you identify as sort of the petri dishes for future threats are also places with tiny gross national products, places that just getting through the day is a big enough threat, much less worrying about tiny viruses and future threats that are somewhere out there in the forest.

NATHAN WOLFE: Look, I think this is a really pivotal point. We will sit with these populations.

And they say: Look, yes, we understand animals get sick and die. We see sick animals. We also know that we can acquire some of these illnesses. Our family members have been hunting and butchering all their lives. You know, this is our primary source, at least for now, for animal protein.

As a virologist, I didn't sort of expect that I would come to advocating for focusing on world poverty and protein alternatives in Central Africa, but that's part of the problem.

RAY SUAREZ: The significance of Wolfe's work is reflected in the organizations supporting him, the Department of Defense, Google, the National Institutes of Health, and the Skoll and Gates foundations, which also fund the NewsHour.

NATHAN WOLFE: Almost every time there's one of these outbreaks, it's a new virus from animals that jump into humans.

RAY SUAREZ: What keeps him up at night and the reason why there has been so much interest in his work is the threat of a super-killer virus that's both easily transmittable and lethal.

NATHAN WOLFE: These viruses mutate at an incredible rate. So something which is highly transmissible, but not very deadly could become very deadly.

When H1N1 was on its way -- the so-called swine flu was on its way racing around the world, one of the dangers is that it would get into some pig or some duck, or even a person that was simultaneously infected with another strain of flu, for example, something like H5N1, and that these viruses would actually sort of mix and match genes.

If that happened, there's that small probability where we would get a virus that had the capacity to spread effectively and had the capacity to kill. And that's the thing that, obviously, we're all afraid of.

RAY SUAREZ: Wolfe says too much attention is placed on responses to outbreaks, and more funding and research needs to be placed on early detection.

NATHAN WOLFE: Pandemic prevention, this is increasingly something that people are recognizing as an issue. But it's going to take some time for the resources to catch up. We need, you know, basically hundreds of millions of dollars to do this work, really, at the end of the day, billions of dollars.

And I just think it can't be reiterated enough. These are not the kind of things that should be cut when it comes time to cutting budgets. If so, we're just sitting there, bullets are dodging left and right, and we're basically ignoring the shooters.

RAY SUAREZ: The book is "The Viral Storm."

Nathan Wolfe, thanks a lot.

NATHAN WOLFE: Thank you.

In NOVA's latest four-part series, physicist Brian Greene covers an astonishing swath of material in the world of physics: quantum mechanics, general relativity, light speed and gravity and the search for elusive subatomic particles. The series is based on his book, "Fabric of the Cosmos."

This week, Hari caught up with Greene to discuss the first installment of the series, "What is Space?" In the series, Greene describes space as a fabric, which can twist, bend and warp in response to gravity. They talk here about dark energy, black holes, our expanding universe and the seemingly wacky idea held that our three-dimensional reality may actually be a sort of two-dimensional quantum illusion.

As river dams age, communities wrestle with how to how to repair and remove them, and a lack of scientific understanding on the subject doesn't help.

How does dam removal affect river systems? Could it cause catastrophic flooding? And how will it change river ecology, river flow, bank buildup or erosion?

Geographer Frank Magilligan of Dartmouth College and his team, who have done extensive research on new Hampshire's Ashuelot River, use laser-based tools and GPS analysis to collect data on such questions, measuring things like topographic elevation, river flow and erosion. Science correspondent Miles O'Brien reports for the National Science Foundation's* latest Science Nation.

For the record, the National Science Foundation is an underwriter of the NewsHour.

More than 500 days of isolation with five other guys ... could you do it? That is what one Chinese man, two European and three Russian men have been through to simulate what humans might encounter if they attempted to venture to Mars. They have missed seasons and friends and for one so-called "simulnaut" - a new wife.

The mock Mars mission ended and the crew emerged into the daylight in Moscow today after 520 days crammed inside a windowless capsule the size of a schoolbus.

See the 12-minute video of the hatch opening and some brief remarks from the crew here at the official Mars 500 page.

While cooped up in a Moscow suburb, they simulated a walk on the Martian surface, rationed their food and even communicated "back to Earth" with a 20-minute delay.

See Miles O'Brien's story on the Mars500 project that we ran on the Newshour this past July.

We also talked with Miles about the piece and the psychological feat the researchers faced:

Keep in mind, this is as much a psychological test as it a physical one. Because unlike actual space travel, there is no weightlessness which can cause muscles to atrophy and bones to weaken from lack of strain. There was also no extended radiation in this experiment, the kind any future astronaut is likely to experience over long periods of space travel. There is also the small matter that an actual mission would take probably twice as long. The crews would land and do research for a year and a half.

Here is a slideshow from February when the simulated spaceship "landed" on planet Mars.

On a regular basis, reporter Jenny Marder tackles a question in science and technology news. It's a feature we call "Just Ask." Today our topic is DNA.

What is noncoding DNA, and why do we need it?

In 1953, James Watson and Francis Crick built a 3-D cardboard cutout model of a DNA molecule shaped like a double helix, and in so doing, divined the structure of DNA.

Since then, the lion's share of genetics research has focused on a small fraction of our DNA -- the genes: the strands of DNA that code for RNA, which make protein. These genes are the blueprint for everything inherited, from height to hair loss to whether we're prone to migraines or motion sickness.

It's all there in the code, but the code is nothing without the stuff that powers the code.

Genes represent only a tiny fraction -- 1 percent -- of our overall genetic material. Then there's the other 99 percent of our DNA -- the stuff that doesn't make protein.

This swath of the genome was once considered "junk," and though a good deal of it is still believed to be nonfunctional, it is now more respectfully referred to as "noncoding DNA." It is still largely an unexplored wilderness -- disorderly and mysterious, but researchers have found that some of this noncoding DNA is in fact essential to how our genes function and plays a role in how we look, how we act and the diseases that afflict us.

Researchers have found that some of this noncoding DNA is in fact essential to how our genes function and plays a role in how we look, how we act and the diseases that afflict us.

Embedded in this 99 percent is DNA responsible for the mechanics of gene behavior: regulatory DNA. Greg Wray of Duke University's Institute for Genome Sciences and Policy describes the regulatory DNA as the software for our genes, a set of instructions that tells the genome how to use the traditional coding genes.

"It's like a recipe book," Wray said. "It tells you how to make the meal. You need to know the amounts. You need to know the order. The noncoding DNA tells you how much to make, when to make it and under what circumstances."

Transcription factors -- proteins that bind to DNA sequences -- function like a sort of molecular switch. Shaped like tiny Pac-Mans with clefts, they attach to stretches of noncoding DNA and modulate whether the gene will be turned on or off, whether it will function and how much protein it will produce.

Here's how it works. When the transcription factors attach, they prompt the regulatory DNA to bend into a hairpin shape in order to make contact with a coding gene, which may be located as far as several thousand base pairs away. Sometimes this contact shuts off the gene altogether; sometimes it makes it go gangbusters making protein.

The location of these binding sites can vary wildly from person to person. And for any one gene, regulatory DNA may include binding sites for 10 or 12 or 20 different transcription factors.

It's the stuff that tells you how to make a single being from a cell, said Michael Snyder, director of the Stanford Center for Genomics and Personalized Medicine. It tells you what goes wrong when you get cancer. "Many think it's not the genes themselves, but how they're regulated that makes us different from one another," Snyder said.

Some rare diseases, such as cystic fibrosis, hemophilia and sickle cell anemia, are caused by a single mutation in coding DNA. In the case of these so-called Mendelian diseases, if you have the mutation, you have the disease.

"These are the classical "genetic diseases" that people generally think about," said Olivier Harismendy of University of California, San Diego, who researches variations in regulatory DNA. "There is very little influence from the other genes or from the environment."

But common diseases are probably more influenced by regulatory differences, Harismendy said. These include Type 2 diabetes, Crohn's disease, Alzheimer's Disease and a variety of cancers, including breast, colon, ovarian, prostate and lung. "Common diseases are usually multi-factorial," he said. "They can have a genetic component, or heritability, but it gives only increased susceptibility, or protection, to the disease."

According to Wray, research has shown that diseases like bipolar syndrome and clinical depression may be associated with noncoding mutations that determine whether the brain is producing too much or not enough of a particular neurotransmitter. One noncoding mutation gives a person almost complete protection against the nasty malaria parasite, plasmodium vivax.

Another piece of noncoding DNA regulates the enzyme responsible for lactose tolerance, the ability to digest milk. Research by Wray and other scientists has shown that in four populations where dairy consumption is a vital part of the diet, new mutations have appeared that essentially keep the gene that produces the lactase enzyme from switching off.

"I think it's a neat example of how the smallest genetic change can give you a new capability to have a new dietary adaptation," Wray said.

And recent research done by evolutionary biologists suggests that differences in regulatory DNA may represent a major part of what separates us from chimpanzees.

But finding the gold among the dross -- the functional parts among the junk in these noncoding regions -- is a tremendous challenge.

Whereas coding pieces have patterns that are easy to recognize, there are far fewer rules when it comes to noncoding DNA, making it a challenge for scientists to identify to which parts of the stuff in between to pay attention and which to ignore.

"People have written fancy computer programs to pull out patterns, but they're fuzzy patterns and there are no hard rules," Wray said. "If you're just scanning visually, there's nothing to tell you this is inherently regulatory in nature versus this does nothing."

Snyder's lab is trying to map all of the elements of the human genome, much of which is still unexplored territory.

"Most of it is mysterious," he said. "Even for genes themselves, we don't always know what they do. And when you get into the noncoding regions, you really don't know."

Many scientific questions remain, including why noncoding DNA works the way it does. Scientists, Wray said, are just now beginning to get under to hood to pick these things apart and determine how it all works.

"We know biochemically how it happens, how a transcription factor interacts with DNA," Wray said. "What's harder to work out is the logic - why some genes have three transcription factors that regulate them and others have 20 transcription factors. We're trying to understand the dynamics of how all the elements interact with each other in a living cell."

Find more coverage on our science page.

This radar image of asteroid 2005 YU55 was obtained at 2:45 pm ET on Nov. 7 when the space rock was 860,000 miles from Earth. Photo by NASA/JPL-Caltech.

As folks on the East Coast are feeding the dog, cooking spaghetti dinner or watching the NewsHour, an asteroid the size of three Manhattan city blocks will barrel by, missing the Earth by a mere 200,000 miles. That's nearly a sideswipe in astronomical terms.

Scientists and amateur astronomers worldwide will have telescopes trained on Asteroid 2005 YU55 as it flies by at 6:28 pm ET tonight. YU55 is egg-shaped, rich in carbon and believed to be among the most primitive objects remaining since the solar system's planet-forming period some 450 billion years ago, and may hold clues to the origins of life on Earth.

It's the closest an asteroid of this size has been to our planet in 35 years and the closest this particular space rock has been in at least 200 years, according to NASA. But, NASA says, its gravitational influence will have no detectable effect on the Earth's tides or tectonic plates.

This Discovery News article has some tips on how to view the asteroid via telescope.

And Joel Achenbach has determined here, using an asteroid impact calculator from Purdue University, that the if YU55 did smack into Earth, it would leave a crater 2.44 miles in diameter and about 3/4ths of a mile deep. But relax, this one poses no hazard to planet Earth.

Listen to the Audio

Can the government track a suspect using a GPS device without a warrant? That question was at the center of a high-profile case before the Supreme Court on Tuesday. Judy Woodruff discusses the oral arguments in the case with the National Law Journal's Marcia Coyle.

JUDY WOODRUFF: Now we turn to the high-profile case before the Supreme Court today, where the justices questioned if the government can track a suspect using a GPS device without a warrant. At the heart of the case is an individual's constitutionally protected privacy in today's high-tech world of real-time surveillance.

Here now to bring us the highlights from today's oral arguments is Marcia Coyle of "The National Law Journal."

Welcome back, Marcia.

MARCIA COYLE, The National Law Journal: Thanks, Judy.

JUDY WOODRUFF: So, tell us first the facts of the case.

MARCIA COYLE: OK.

The police and the FBI attached a GPS tracking device to the undercarriage of Antoine Jones' car. Jones was a suspected drug dealer. They didn't have a warrant. They monitored the movement of the car 24 hours per day for 28 days. Some of the information gathered was used to convict him of conspiracy to deal drugs.

A federal appellate court later reversed his conviction, finding that the use of the GPS device without a warrant violated the Fourth Amendment.

JUDY WOODRUFF: So what is then the question before the justices?

MARCIA COYLE: Well, Judy, as you know, the Fourth Amendment protects us from unreasonable searches and seizures. The Supreme Court has said, in determining whether a search or seizure was unreasonable, you have to look at the individual's expectation of privacy, and was that expectation reasonable in itself?

So the question here is, did -- was there a reasonable expectation of privacy on the part of Jones that the police could not use the GPS tracking device?

JUDY WOODRUFF: So how is new technology -- I know GPS has been around for a while. It's not one of the newest of the new. But how is new technology playing into this argument?

MARCIA COYLE: The court actually faced the new technology a bit last year when it took up a case involving text messages on a pager. And the lower courts are struggling with police use of information from cell phones, smartphones, computers.

It's a very unsettled area of the law. The GPS tracking device has troubled lower courts as well. So lower courts in particular -- and police -- are looking for some guidance from the Supreme Court in this particular case.

JUDY WOODRUFF: So, it sounds like today, from what I read, the justices were asking a lot of questions.

MARCIA COYLE: It was a very active argument. It was the government that brought the appeal to the Supreme Court, since they lost below.

And Deputy Solicitor General Michael Dreeben, representing the government, told the justices that earlier Supreme Court cases have said there is no reasonable expectation of privacy when you travel on public roads. The GPS device, he said, exposed nothing that wasn't already exposed to anyone who cared to look at this car.

And he also said it was no different than if the police had assigned 10 agents to tail Jones' car for 24 hours a day for a month.

JUDY WOODRUFF: And how did the justices response to this line of argument?

MARCIA COYLE: The justices -- a number of the justices seemed very uncomfortable with how far the government's argument went.

Justice Breyer, for example, said, if you win, you would be able to monitor the movements of every citizen in the United States, and that suggests sort of an Orwellian, "1984" scenario. So he pressed -- and so did the other justices -- pressed the government on what protection is there here from something like that happening?

And Mr. Dreeben said, well, there are other constitutional principles that can come into play if there are abuses or if the court is afraid that something is chilled here. There's the First Amendment. There's equal protection.

But he said, we're not talking about monitoring every citizen. This is a case where police were monitoring a suspected drug dealer.

JUDY WOODRUFF: And it almost sounded as if, from what I was reading, that when the attorney for the plaintiff came before -- for the man who had been convicted came before the justice, they were almost helping his attorney make his argument.

MARCIA COYLE: Well, I think they actually gave him an equally hard time in some respects.

Stephen Leckar was representing Mr. Jones. And, of course, he disagrees with the government. He said no one expects the government to surreptitiously, without a warrant, attach a tracking device to your car and monitor you.

Justice Ginsburg said, well, you know, many cities have cameras attached to traffic lights. And they monitor the movement of cars to look for traffic violations. But Mr. Leckar insists that what's different here is, this is a physical invasion of property. It's a greater intrusion on your privacy than cameras or video observation.

JUDY WOODRUFF: So, finally, Marcia, what's -- the sense is, what, that the justices could draw a line, privacy, high-tech device, that they could choose to draw that narrowly, broadly? What?

MARCIA COYLE: They could. There is a narrow way to solve this -- or resolve the case. And that is just to look at the attachment of the GPS device, was that a seizure, and not deal with the more complicated issue of search and reasonable expectations of privacy in the world today.

I thought Justice Alito had a -- really hit the nail on the head when he said, before the Internet age, our sense of -- much of our privacy resulted from difficulty in traveling and gathering information. But with computers, you can now amass a huge amount of information. He said, so what now? Is everything fair game? Or where are the limits?

And that's what the justices have to juggle. Where -- or is there a limit? Is there a line to draw?

JUDY WOODRUFF: Fascinating.

MARCIA COYLE: It is.

JUDY WOODRUFF: Marcia Coyle, thank you.

MARCIA COYLE: My pleasure, Judy.

We officially launch a new feature today we're calling "Science Thursday." Each week, we'll feature an online-exclusive multimedia piece on a topic in the world of science and technology.

Here's what's up first. On Thursday's NewsHour, science correspondent Miles O'Brien reports on a grassroots group called Safecast that is measuring and mapping data on radiation contamination from locations around Japan after this year's devastating earthquake.

While in Tokyo, Miles spoke to Hari Sreenivasan about his trip with Safecast workers into the voluntary exclusion zone around the Fukushima Daiichi nuclear plant, where they detected levels reaching the equivalent of six X-rays per day.

He also filled us in on his conversations with Japanese officials working in evacuated areas and Japanese residents eager for more information about the consequences of the nuclear accident.

Find more coverage on our science page.

While shooting, the NewsHour and Safecast crew encounter an abandoned dog. Photo by Sean Bonner of Safecast.org.

Update: 4 pm ET, Nov 11|

At the tail end of Miles O'Brien's latest NewsHour report on radiation in Japan, a golden dog with a thick red collar trots into the street of the abandoned town, Katsurao, and weaves along the center divider.

Miles asks, off camera: "Do we have anything to feed him?"

The piece, which airs tonight, reports on the group Safecast, which has measured, mapped and crowdsourced data on radiation levels in locations throughout Japan, particularly in the hot spots near the Fukushima Daiichi nuclear plant.

The dog was one of several scrawny, undernourished dogs and cats they encountered, most likely abandoned by their owners during rapid evacuation. (The crew did, incidentally, have food in their supply for the dog - sweet buns with bean paste and sushi.)

Signs of the animals were everywhere, according to Xeni Jardin, who produced and helped shoot the piece. Bowls filled with dog food by a makeshift police station. A dog emerging from a cluster of houses near a stream. A cat poking its head out from behind the corner of an abandoned house. And on a lamppost, a sign with pictures of various dogs that had been rescued from the area, one of which has since been found.

"These were not feral cats and dogs," Jardin said. "It's obvious they were part of someone's family. As you feel empathy for these abandoned creatures, you start to feel the scope of the disruption and abandonment and complete destruction of the social fabric in Japan. The Japanese are very, very sweet to their pets."

Indeed, Japan is known for its animal lovers. After all, this is the land of cat cafes, where people pay by the hour to get their feline fix, hanging out and relaxing with resident cats. Some of these cafes are so crowded that reservations are recommended on weekends.

The dogs and cats spotted in Katsurao were were among thousands of pets abandoned after residents were forced to quickly evacuate areas around the Fukushima plant, after the tsunami damaged the facility, causing equipment failures and a release of radioactive materials.

"I think people expected not to be out of their homes for any length of time," said Ian Robinson, animal rescue program director for the International Fund for Animal Welfare, one of the groups that traveled to the evacuation zone after the disaster.

Upon visiting the area after the earthquake, Robinson's group found that many local Japanese groups were eager to help with animal rescue efforts, but there was confusion as to whether the animals in the radiation hot spots were safe to handle and how they should be tested for contamination. (As one of our readers pointed out, the Hachiko Coalition is an organization that has done a great deal of animal rescue work in the Fukushima radiation zone.)

They gathered international experts, produced a report in May and gave it to the Japanese government. "We hoped that would free up the ability of the government and NGO's to remove animals," Robinson said. "To a certain extent that happened, though as always with these things, they don't happen as well and smoothly as we would like. There have been holdups."

Among the recommendations, they suggested that each team be equipped with protective equipment and a real-time dosimeter to measure radiation, that animals be bathed with soap and warm water, and that feeding stations be strategically placed to coax animals out from restricted zones.

As long as the animals are appropriately cleaned and quarantined, they should be ultimately safe to handle and adopt, said Timothy Mousseau, a professor of biological sciences at the University of South Carolina, who has extensively studied animals -- mostly birds and insects -- exposed to radiation.

Most of the area's contamination derives from cesium that was released as a product of fission from the nuclear reactors, he said. Cesium, which has a half life of 30 years and produces low levels of gamma radiation, is less chemically toxic than the uranium or plutonium released after the 1986 accident at the Chernobyl Nuclear Power Plant in Ukraine.

Animals will eventually eliminate the radioactive material from their bodies, Mousseau said, though that could take anywhere from a week to 4 to 5 months, depending on their size and the degree of contamination.

"Since it's cesium, it will get cleared from their bodies," he said.

But for animals and people, there are still many unknowns about the radiation risks, and the harm that it might cause. As Miles reports in his piece, "There is no question that ionizing radiation alters human cells, which can cause cancer and genetic defects ... but how much exposure and for how long? The science, like the readings, is all over the map."

In one area that Miles and the crew visited, for example, levels reached the equivalent of six X-rays a day.

There is the possibility for radiation exposure during rescue, Robinson said. "The danger is not visible, like a fire or a flood where you can see the danger, but it's still very, very real," he said. "That's something that has to be borne in mind."

Mousseau's research has found significant genetic damage and breakages in chromosomes among animals exposed to radiation in and around Chernobyl. Developmental abnormalities, tumors, and species decline and extinction have also been attributed to radiation exposure in the area.

The area around Fukushima happens to share 14 species of birds also found around Chernobyl, including the barn swallow. Given the contamination levels reported by citizen groups, it's possible that we could also see "multigenerational effects" and fundamental changes in the ecosystem in Japan as a result of the disaster, he said. Research in the area by his team and others should provide a greater understanding of the effects of radiation exposure on birds and other wildlife.

"What Fukushima offers us as scientists is the opportunity to watch how these populations and communities change over time as a result of radioactive contaminants," Mousseau said. "In Chernobyl, everything was top secret. We don't really know how things began. Fukushima offers us the opportunity to follow these organisms from the beginning."

Find more coverage on our science page.

Listen to the Audio

Should President Obama approve a major extension of the Keystone XL pipeline? Ray Suarez discusses that question, which has divided business, environmental groups and labor unions, with The Washington Post's Juliet Eilperin.

JUDY WOODRUFF: And to the Obama administration's move to delay action on a contested oil pipeline until after the election.

Ray Suarez has the story.

RAY SUAREZ: The question is, should the president approve a major extension of the Keystone XL pipeline? It's a debate that divides business, environmental groups and labor unions.

The pipeline would carry oil more than 1,700 miles from the tar sands of Canada to Port Arthur in the U.S. Gulf Coast, passing through half-a-dozen states along the way. In one, Nebraska, there was significant opposition to the plan.

This afternoon, the State Department said it was concerned about the Nebraska part of the route and said finding and reviewing an alternate path could take until 2013.

The president backed the delay, saying: "We should take the time to ensure that all questions are properly addressed and all the potential impacts are properly understood."

For more, I'm joined by Juliet Eilperin of The Washington Post.

Juliet, what did the State Department tell the pipeline developers to do, and what reason did they give?

JULIET EILPERIN, The Washington Post: What they said is actually that they would re-examine other routes within just Nebraska, and that TransCanada, which is the company that is sponsoring this pipeline, would, of course, have to sketch out how that could be done.

And then they would examine whether it could protect a particular reason known as the Sand Hills region within Nebraska, which is where you have seen intense opposition over this project.  

RAY SUAREZ: It's unusual to have the U.S. State Department making pronouncements on Nebraska, isn't it? Why is the State Department ruling on a pipeline that runs for almost its entire length through the United States?

JULIET EILPERIN: Interestingly, the reason they have jurisdiction is simply because it's a pipeline that crosses the U.S.-Canada border. That makes it something that comes under the purview of the State Department, and not other agencies, like the Department of Transportation, which has an agency which traditionally looks at pipelines and how they are handled and constructed.

RAY SUAREZ: Does redrawing the path of the pipeline mean, in effect, starting from scratch, really going back to the drawing board on this?

JULIET EILPERIN: It doesn't mean starting from scratch, but it certainly raises questions about the economic viability of a project that's been under scrutiny for more than three years, and now we're adding at least 15 months to this decision.

So it raises questions about whether, in the end, TransCanada will pursue this, although they do say that they remain hopeful that they will get approval and they're going to go back and look at it.

RAY SUAREZ: Fill us in on who -- how the battle lines have been drawn on this. Who, broadly speaking, is for it, who is against it, and where was the president on all of this?

JULIET EILPERIN: It is interesting.

So, in terms of the proponents, you have an interesting mix of, say, business groups, oil companies, but also labor unions. There are four key labor unions, including plumbers and pipe fitters, operating engineers and so forth, who would benefit from jobs that would be created either by supplying the materials for the pipeline or for constructing and operating it.

As -- and on the other side -- and you also had the Canadian government, which has been lobbying aggressively to get this passed. On the other side, you have environmentalists, as well as an eclectic mix of folks along the route of the pipeline, which included ranchers and farmers in Nebraska and elsewhere, as well as some Tea Party activists and other conservatives who didn't like the idea that TransCanada might say that their land had to be used for this pipeline.

So it divided the president's base. And he had been largely silent about this until just recently, where he did a public interview with an Omaha, Neb., TV station. And it is at that point that he really said that he would be involved in this decision, even though it would be done by the State Department, and that he wanted to weigh these public health and environmental considerations against what he called a few thousand jobs that would be created by the project.

RAY SUAREZ: So how have these various groups that you have sketched out for us reacted to the announcement of the delay?

JULIET EILPERIN: Well, unsurprisingly, what you have had is much enthusiasm from environmentalists and from folks in Nebraska and those along the route who had been opposing it who see this is likely to be a death knell for the pipeline, even though we are not sure whether that is the case.

On the other hand, you have some oil companies, including the head of the American Petroleum Institute, Jack Gerard, who have been scathing in their critique and essentially said this is a move that will undermine jobs. You have had Republicans make that point as well.

RAY SUAREZ: What about the Canadians? Have they had anything to say on this?

JULIET EILPERIN: The natural resources minister has. I have been trying to get in touch in folks. The Canadian ambassador is traveling.

But the natural resources minister said that he remains hopeful that this pipeline will be pursued, that they are not giving up, and that he argued that it would be undermining the United States in terms of both the energy security it could get by getting a supply of oil from a friendly ally, as well as the potential jobs. And so they're saying that they are still going to push for it.

RAY SUAREZ: The length of this delay, 13 to 15 months, that means it's either the early months of a new Obama administration or, in fact, the next president of the United States will make this decision, right?

JULIET EILPERIN: Absolutely.

And one of the critiques that some environmentalists have made is, you know, we're celebrating this, but actually this ultimate decision could be made by a president who might not share our environmental values. So there's no question this pushes it past the 2012 election. And then the real question is, will Obama make the final decision about this controversial project, or will it be a Republican who would be in office instead?

RAY SUAREZ: After the project is redesigned, what's the presidential role? Are we still at the point where whoever is making the decision, whatever president is sitting in the Oval Office will still be considering this possibility?

JULIET EILPERIN: Well, it will still be within the purview of the State Department, but, yes, ultimately, the president can -- first of all, at any point -- the president has delegated this responsibility to the State Department. The president can take it back.

And so at the end of the day, it will be the president, whether it's President Obama or the person who follows him, who will say yea or nay to this project.

RAY SUAREZ: Juliet Eilperin of The Washington Post, thanks for joining us.

JULIET EILPERIN: Thank you, Ray.

Listen to the Audio

Eight months after a tsunami caused a nuclear accident in Japan, ordinary people are using new technology and the power of crowdsourcing to find radiation hotspots. NewsHour science correspondent Miles O'Brien reports from Japan.

JEFFREY BROWN: Now, tracking the spread of radiation in Japan eight months after the tsunami caused a nuclear accident.

Japanese people are using new technology and the power of crowdsourcing to find hotspots.

NewsHour science correspondent Miles O'Brien has the second in a series of stories from Japan.

MILES O'BRIEN: In Japan, these days, you never know where you're going to find a hotspot. We are at a highway rest stop halfway between Tokyo and Fukushima, and we are looking for the kind of hotspot you would just as soon avoid.

PIETER FRANKEN, Safecast Japan: On the roof, the cesium didn't really stick very well, so it all flushed down and when it hit the concrete or the stone here, it bonded. So this is like a micro hotspot.

MILES O'BRIEN: It's just another Sunday drive for Pieter Franken and his Safecast team of volunteer radiation contamination gumshoes using inspiration, perspiration, sensor technology and the Internet to paint a much clearer public picture of the Fukushima fallout.

It is crowdsourcing of science in action.

BRYAN MOROSS, Safecast volunteer: We are about 60 kilometer to Fukushima. We should be there in about an hour. We should be there around 12:30.

MILES O'BRIEN: We were heading north to the evacuation zone around the Fukushima Daiichi nuclear plant, about 40 miles away. We gather radiation readings in the air and on surfaces with Geiger counters in and outside of the vehicle. Using a handful of devices, we measured raw radiation levels, counts per minute, as well as becquerels and microsieverts, which calibrate the raw numbers to their impact on human beings.

SEAN BONNER, Safecast: So these are the microsieverts. You can see they're considerably lower than they were just a few minutes ago.

MILES O'BRIEN: Sean Bonner is one of the founders of Safecast, an all-volunteer organization that has plotted the most detailed maps of radiation contamination in Japan since the nuclear meltdown in March.

Radiation doesn't fit that nice, neat little disk they want to paint on the map, right?

SEAN BONNER: Right. Right. Yes. Radiation isn't looking at a compass radiating outward.

MILES O'BRIEN: Yes. That's right. It's a very arbitrary thing.

SEAN BONNER: Yes. There's like wind and topography and this crazy stuff that ends up playing into it.

MILES O'BRIEN: Wherever they go, they draw a crowd, a curious, nervous, thankful crowd. In a restaurant parking lot in Nihonmatsu, about 60 kilometers from the nuclear plant, we met Hiroko Ouchi.

"I'm worried about my children and grandchildren," she told us. "Thank you for measuring. Thank you for your hard work. The government doesn't release the accurate figures of radiation."

MAN: Thank you very much. Thank you for working so hard. Thank you.

MILES O'BRIEN: But it's not just a lack of data. There is also a tradition here of not sharing it.

JOI ITO, MIT Media Lab: Japan is notoriously bad about certain types of transparency. And it's not -- this isn't a new thing that TEPCO covers things up.

MILES O'BRIEN: Joi Ito sparked the birth of Safecast in the desperate days right after March 11. Director of the MIT Media lab, he naturally took to the Internet to try to stay abreast of events in his home country. The scarcity of reliable information prompted him to reach out to experts all over the world. Things snowballed very quickly.

JOI ITO: Within days, we had an email thread that turned into a Skype channel where all of us were constantly there talking. And it really became kind of like across between a sort of government situation room and newsroom, where we were collecting data and just sort of putting new things out, and just trying to get everybody involved that we could.

And it just kind of took a life of its own. We started to realize how important it was when it turned out that the government wasn't releasing data.

MILES O'BRIEN: The day before we took our drive, Safecast volunteers offered up a seminar on radiation detection in Tokyo. It was standing room only for the talk and many stuck around to get some advice on how to accurately measure the radiation around them.

Many Safecast volunteers come from the computer hacker community. Their intuition and ingenuity led them to design and build some novel devices to gather radiation data.

Akiba (ph) -- he doesn't use his surname -- showed me what they call a B-geigie.

What does that stand for?

MAN: Bento geigie. So, when we originally designed it, we tried to design it to be like roughly the same form and factor as a bento, so that's easy to carry around. Like, a bento is a Japanese lunch box.

MILES O'BRIEN: But instead of sushi, this box contains a Geiger counter, a GPS receiver and an S.D. Card. It costs $850 to build, but Safecast is making them available to volunteers for free.

During our drive north, the Safecast team delivered a B-geigie to Hideki Washiyama (ph), who lives about 90 kilometer from the Fukushima Daiichi plant.

"It is hard to get high-quality Geiger counter," he told me, "but I don't want to use cheap devices made in China or Korea."

There are plenty of cheaply made, yet disturbingly expensive Geiger counters in Japan. The Fukushima meltdown created an instant global shortage of good-quality sensors. Concerned people in Japan and elsewhere sparked overwhelming demand.

Dan Sythe produces good-quality Geiger counters in Sebastopol, Calif. He says that the shoddy devices so commonly found in Japan are extremely dangerous.

DAN SYTHE, Iospectra-International Medcom: Because people are waving these over their food and thinking the food is safe to eat or they're thinking that where they're living is safe and safe for their children to go to school. So it's -- I think it's almost criminal to produce things that don't work.

MILES O'BRIEN: Sythe's small company is shipping out as many Geiger counters as it can, giving priority to Japan, and specifically Safecast.

Volunteer Joe Moross says more comprehensive monitoring is the first step to understanding the real danger.

JOE MOROSS, Safecast volunteer: I don't think that ordinary people can make a good valuation of the risk, because even the specialists are in quite a bit of disagreement as to what the real risk is.

MILES O'BRIEN: And so the reaction is, I want none. If you don't know, give me zero, right?

JOE MOROSS: Well, everybody agrees, no matter -- you can't find anyone who doesn't agree that lower is better, that less radiation is less harmful.

MILES O'BRIEN: Ironically, much of what we know about the effects of an acute dose of radiation comes from studying Hiroshima and Nagasaki survivors. But radiation contamination at the level found here is a ticking time bomb with a fuse that burns for decades.

There is no question ionizing radiation alters human cells, which can cause cancer and genetic defects, but how much exposure and for how long? The science, like the readings, is all over the map.

This is the town of Minamitsushima (ph). We are about 28 kilometers from the Fukushima Daiichi plant, about one kilometer from the police barricade announcing the involuntary exclusion zone. This area, 20 to 30 kilometers, is a voluntary exclusion zone. And you don't see anybody around, for good reason.

PIETER FRANKEN: Yes, this is very high here, really high. We are looking at air one meter, around 7.2 -- to 7 to 8 microsieverts per hour. We're looking here at around 24,000 counts per minute on the pancake and about roughly about 800,000 becquerel per square meter. It's about 25 times what we're seeing in Tokyo on the surface.

MILES O'BRIEN: It was five microsieverts per hour, most likely cesium 137, which has a half-life of 30 years. It is the equivalent of six chest X-rays every day, not a problem for us to be here for a short while in street clothes, but how long before people could live here again?

PIETER FRANKEN: If you wanted to get this down to levels that are considered normally to be safe, which will be under 0.3 microsieverts per hour, you would probably look at much more than 20 years or 30 years.

MILES O'BRIEN: But down the road, at the exclusion zone checkpoint, the police officers ordered to be here are hoping for the best.

You don't worry?

MAN (through translator): They have told us there that we're OK, so we just need to trust them.

MAN: I agree.

MILES O'BRIEN: Do you trust them?

(LAUGHTER)

MAN (through translator): That is what our bosses say, so we need to trust our bosses, yes.

MILES O'BRIEN: But Safecast believes people should trust in the data, and the more people who are gathering it, the better. Volunteers are designing a new, sleek, inexpensive Geiger counter that they hope to begin distributing in the spring.

But the nonprofit is not stopping there or here.

JOI ITO: I think the goal really is, when we started to try to solve the data scarcity problem about Japan, we realized that there was a systemic problem in the way that data is collected and disseminated and interpreted everywhere. And we're already starting to think about, how do we measure pollution, how do we measure all kinds of other things?

And so, I think a lot of things will come out of this incident. And, so, this democratization of science is really, really important in fixing the world's problems, because it's not going to happen top-down.

MILES O'BRIEN: Are you guys anti-nuclear, or do you take a position? Or are you just...

SEAN BONNER: No. No, not at all.

MILES O'BRIEN: You're just pro-data.

SEAN BONNER: We just know that there's data that exist and there's data that should exist. And creating it, the data doesn't take a side one way or the other. And so if we just can get the data and give it to the people that are being immediately affected by it, then that's a good thing.

MILES O'BRIEN: With light dimming, our Sunday drive for data ended here in the town of Katsurao, adding about 12,000 readings to a database of more than 1.25 million.

No one is here, only the police, making sure we were not looters. And so it is hard to say if this lonely dog will ever see its owners again.

Do we have anything to feed him?

Sadly, no amount of data-gathering can change that fact or erase this scene.

JEFFREY BROWN: We have launched something new on our Science page online. It's called Science Thursday. Each week, we will feature a fresh video, slide show or blog post. Tonight, find photos and a story about the fate of dogs and cats abandoned in the exclusion zone. Plus, Miles talked with Hari about his reporting trip to Japan.

A worker cleans and lubricates the head of a hydraulic fracturing machine at Southwestern Energy Co.'s natural gas production site at the Marcellus Shale formation in Camptown, Pa. Photo by Bloomberg via Getty Images.

The biggest earthquake ever recorded in Oklahoma struck on November 5, a magnitude 5.6 temblor that buckled a highway and ruptured water pipes. This quake is part of a skyrocketing rise in seismic activity the state has seen in the past three years, leading many to wonder--and worry--about its cause. Might the practice of fracking, a controversial method of drilling into rock for natural gas, be to blame?

The earthquake struck around 10 p.m.. local time about 50 kilometers east of Oklahoma City, and was felt from Saint Louis to Dallas. Until then, the state's largest temblor was a magnitude 5.5 event near the town of El Reno in 1952.

Overall, only minor injuries and damage were reported after last weekend's earthquake. A magnitude 4.7 foreshock preceded the quake by about 20 hours, and dozens of aftershocks were detected as well. These all apparently happened on the well-mapped Wilzetta Fault. "It seems the east side of the fault moved a bit southward," says seismologist Randy Keller, director of the Oklahoma Geological Survey (OGS).

The recent uptick in the area's temblors has been dramatic. From 1972 to 2008 only two to six earthquakes were reported per year in Oklahoma, and were often too small for people to notice. However, in 2009 nearly 50 earthquakes were recorded, and that number more than doubled in 2010 to 1,047, with 103 powerful enough to be felt.

This unusual seismicity has led some to wonder about increased activity in the area related to fracking, or hydraulic fracturing, which uses millions of gallons of fluid to break apart rock and release natural gas. The practice generates a considerable amount of waste liquid, which is often disposed of by injecting it into deep rock formations where it can lubricate faults. Hydraulic fracturing is common in Oklahoma, the nation's third-largest producer of natural gas, and has taken place there for decades (pdf). Now, with the discovery of natural gas deposits in other regions of the U.S., the extraction method is being used more widely and has raised concerns about its potential to contaminate drinking water.

Fracking has been linked to two minor earthquakes in northwest England, very likely by lubricating an already stressed fault zone and thus making it easier for the land to shift (pdf). A report in August (pdf) by seismologist Austin Holland at the OGS also suggested that a swarm of nearly 50 small quakes of magnitude 1.0 to 2.8 near the center of the state might have been triggered by nearby fracking.

Still, researchers say it seems unlikely that fracking had anything to do with last weekend's magnitude 5.6 quake. "There was a lot of deformation of the Earth here 300 million years ago that created huge geological structures in the subsurface that shift from time to time," Keller says. "We have an unstable situation here, and it's one reason why oil and gas is available here in the first place."

"I won't say that man's activity never ever caused the release of seismic stress, but hydro-fracks are such small things," Keller adds. "If we were talking a magnitude 1 or 2 earthquake, that'd be different, but it's awfully hard to imagine a hydro-frack being involved with one of this size. We also have to determine if there were any frack jobs going on there right now, but I don't think there were--it didn't happen in an area of particularly active oil and gas exploration."

As to whether the spike in earthquakes recently seen in the state might be due to fracking, "it is probably best not to attach much significance to perceived increases in seismic activity in Oklahoma--the occurrence of earthquakes anywhere is quite irregular," says seismologist Art McGarr with the U.S. Geological Survey. This surge in quakes might be a temporary statistical anomaly.

"It may be, however, that more earthquakes are being induced in Oklahoma because of an increase in disposal well operations and, indeed, research is going on now to investigate this possibility," McGarr says. The large amounts of fluid disposed of in this way can seep into cracks and lubricate already stressed faults, making it easier for them to slip and cause an earthquake." No answers yet, however."

Scientists had three or four seismographs positioned at the epicenter of the earthquake when it occurred, and another 25 to 30 will be deployed there now or soon to study aftershocks and locate the November 5 quake's origin more precisely. "In a few weeks or a month we may have a better idea of what might have caused this earthquake sequence--natural tectonic processes or industrial activities," McGarr adds.

This article is reproduced with permission from Scientific American. It was first published on November 14. Find the original story here.

The world's biggest dam removal project -- and the second-largest environmental restoration project in U.S. history -- is in progress on the Elwha River on the Olympic Peninsula in Washington state.

The Elwha Dam and the Glines Canyon Dam blocking the Elwha River are coming down due to aging infrastructure and as part of an effort to restore fish runs. When the dams were built in the early 1900s to provide hydroelectric power to nearby residents, they were installed without a way for fish to pass. Ever since, prime habitat upstream on the Elwha has been inaccessible to salmon.

Environmental reporter Katie Campbell of KCTS9 in Seattle has been tracking the ecosystem restoration in conjunction with the dam removals on the Elwha. Deconstruction began this past September, and it will take up to three years to completely remove the dams. Rather than knocking out the dams with dynamite, construction teams are breaking them into sections, digging them out, and hauling them away.

Campbell recently went out with a team of scientists and members of the Lower Elwha Klallam Tribe to report on the first coho salmon to be reintroduced into the upper reaches of the Elwha River. In an interview with Hari Sreenivasan, Campbell explained that there were once hundreds of thousands of salmon, but now numbers have dropped to critical levels.

Hundreds of hydropower dams across the country are slated for removal as they deteriorate and as concern for disappearing species grows. "All eyes on the Elwha, to see what lessons we can learn here about taking out large dams and to see what happens to an ecosystem when you take these large structures out of it," said Campbell.

Watch a time lapse of the first months of deconstruction on each of the dams:

Follow @Hari and @EarthFixMedia on Twitter.