Articles from Scientific America

Whereas most discarded plastic water and beverage bottles (those imprinted with a number 1 within a triangular arrow) can be recycled , the resulting second-generation plastic is generally unusable for making new plastic bottles. This is because the polyethylene terephthalate (PET) thermoplastic polymer used to make the original bottles is often made with the help of metal oxide or metal hydroxide catalysts that linger in the recycled material and weaken it over time. [More]

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Last week, the new Advanced Research Projects Agency for energy held its inaugural conference in Washington, D.C.--a direct response to a growing sense that the U.S. is losing its technology lead when it comes to the race for cleaner ways to produce and use energy. "We have a Sputnik moment right now. We are losing our technology leadership and we are falling behind."

Editor's Note: Journalist and crew member Kathryn Eident and scientist Jeremy Jacquot are traveling on board the RV Atlantis on a monthlong voyage to sample and study nitrogen fixation in the eastern tropical Pacific Ocean, among other research projects. This is the sixth blog post detailing this ongoing voyage of discovery for ScientificAmerican.com .

Imagine you’re in space, floating high above the Earth. Picture the world’s oceans, glimmering sapphire under the heat of the sun and the protection of the ozone layer. Look closer, there’s a patch of brown in the middle of all that blue. It’s a bloom of phytoplankton called Trichodesmium , a “world famous” nitrogen fixer. [More]

Religious belief may seem to be a unique psychological experience, but a growing body of research shows that thinking about religion is no different from thinking about secular things­--at least from the standpoint of the brain. In the first imaging study to compare religious and nonreligious thoughts, evaluating the truth of either type of statement was found to involve the same regions of the brain.

Researchers at the University of California, Los Angeles, used functional MRI to evaluate brain activity in 15 devout Christians and 15 nonbelievers as the volunteers assessed the truth or falsity of a series of statements, some of which were religious (“angels exist”) and others nonreligious (“Alexander the Great was a very famous military ruler”). They found that when a subject believed a statement--whether it was religious or not--activity appeared in an area called the ventromedial prefrontal cortex, which is an area associated with emotions, rewards and self-representation.

Everyone knows that obesity is bad for your health. Packing on the pounds, we’re told, leads to all sorts of medical problems: high cholesterol, insulin resistance, greater risk of diabetes and heart disease. But researchers at the University of Texas Southwestern Medical Center see things a little differently. In a paper in the journal Trends in Endocrinology and Metabolism [see http://bit.ly/bKaP33 ], they argue that being fat can actually protect us from these disorders. [More]

There’s a story about a truck driver who passed the long, lonely hours in his big rig knitting sweaters. His hands thus otherwise occupied, he steered with his knees. A highway patrol officer noted this behavior and set out after the truck driver. As the cop got close, he commanded via his vehicle’s loudspeaker, “Pull over.” To which the trucker shouted back, “No, it’s a cardigan.”

Though not a bona fide law-enforcement officer myself, I sometimes act in loco centurion while on the road. I do this by sharing safety tips with distracted motorists, such as “Slow down!” or “Pick a lane!” or, my go-to line, “Get off the phone!”

When the weather cools, ectothermic (cold-blooded) animals slow down, which should be good news for their potential prey. But the colorful chameleon has found a way to keep feeding at top speeds even in lower temps: an elastic-tissue tongue, which unlike regular muscles, can uncoil nearly as fast in lower temperatures as it can in warmer ones. [More]

Children, like adults, use three visible cues--race, gender and age--to arrange their social world. They prefer to make friends with kids similar to them on these traits. New research shows that verbal accents may be equally important in guiding youngsters’ social decisions--in fact, accents may be even more important than race.

Working at Harvard University, developmental psychologist Katherine D. Kinzler and her colleagues first showed American five-year-olds photographs of different children paired with audio clips of voices and asked which ones they preferred as a friend: a child who spoke English, one who spoke French, or one who spoke English with a French accent. Even though the subjects understood the French-accented English, they were almost four times more likely to choose the native English speaker as a friend.

So, they’re scanning your items at the grocery store, and when the last tomato gets bagged you’re stunned at the cost. How did you spend so much? Maybe those cherries were 12 bucks a pound. Or maybe you should have paid more attention to what you put in the wagon. Then again, maybe not. Because a new study in the Journal of Marketing [see http://tinyurl.com/yl5dbxg ] shows that the harder shoppers try to keep track of what they’re spending, the worse they actually do. [More]

Vitamin D deficiency has been linked to a rapidly expanding inventory of ailments--including heart disease , cancer and the common cold . A new discovery demonstrates how the vitamin plays a major role in keeping the body healthy in the first place, by allowing the immune system's T cells to start doing their jobs.  [More]

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That’s a scene from the 1968 movie The Party with Peter Sellers attempting small talk. And sometimes small talk can lead to interesting connections.

Nine months after it created its first list of protected endangered species , the government has added 15 more to the list, including what has been billed as "the world's least-known bird." [More]

Outnumbering our human cells by about 10 to one, the many minuscule microbes that live in and on our bodies are a big part of crucial everyday functions. The lion's share live in the intestinal tract, where they help fend off bad bacteria and aid in digesting our dinners. But as scientists use genetics to uncover what microbes are actually present and what they're doing in there, they are discovering that the bugs play an even larger role in human health than previously suspected--and perhaps at times exerting more influence than human genes themselves. [More]

At Perceptive Pixel 's offices on Manhattan's West Side, Jefferson Han stands in front of a megasize multi-touch screen and runs his fingertips across the display. Each finger leaves a trail of colored pixels in its wake, causing the display to look, briefly, like it has been scratched by a set of digital claws. [More]

Hold onto your remote control: 3-D television is on the way . By the end of the year, most of the major TV manufacturers, including LG Electronics, Panasonic, Samsung and Sony, will be selling displays capable of showing 3-D movies and other programming. Unfortunately, none of the models going on sale this year will eliminate the least pleasant aspect of the 3-D viewing experience--those often uncomfortable and frequently silly-looking spectacles. 3-D TV for the naked eye does not exist--at least not yet. [More]

Although any T. Rex –enthralled kid will tell you that a gigantic asteroid wiped the dinosaurs off the planet, scientists have always regarded this impact theory as a hypothesis subject to revision based on further evidence gathered from around the globe. Other possible causes, such as volcanism and smaller, multiple asteroid strikes, never actually went away, and over the years researchers raised important points that did not fully jibe with a history-changing celestial impact near the Yucatan peninsula one awful day some 65.5 million years ago. [More]

Dutch and U.S. researchers are testing new acoustics technology that could be mounted on the outside of small aircraft, listening for characteristic sounds that indicate the presence of other fliers. Called an acoustic vector sensor (AVS), the system uses nanoscale materials to alert pilots to other aircraft within about 10 kilometers, a system that may help prevent midair collisions such as the one between a private plane and a sightseeing helicopter over New York City's Hudson River in August 2009, the researchers say. [More]

Dear EarthTalk: A fisherman friend of mine told me that trout populations in the interior West of the U.S. are already shrinking due to global warming. Is this true? And what is the long term prognosis for the trout? --Jon Klein, Portsmouth, N.H. [More]

When science revises its stance, the field itself follows established protocol to adapt, but public opinion can be slow to catch up. Rather than wiping the slate clean, last month's retraction of a key paper proposing a link between childhood vaccines and autism seem only to have widened the societal divide on the issue. And the rising rate of retractions--roughly ninefold between 1990 and 2008--suggest that there could be more cases in which public opinion carries on long after science has reversed course. [More]

It looked like a dinosaur , walked like a dinosaur, and ate like, well, some dinosaurs, but a newly discovered species of archosaur, which lived 240 million years ago, was not a dinosaur. [More]