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    A Tweet In Time Astronaut Chris Hadfield tweeted this photo, of the Richat Structure of Mauritania, from space. And he's right when he tweeted it's "[u]ndoubtedly one of the coolest space sights on Earth." Chris Hadfield
    Including moth wings in macro, a hidden leopard and more

    Click here to enter the gallery

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    This Week In The Future, January 14-18, 2013Baarbarian
    In the future, Paleo's, with its retro sensibilities, will trounce other fast-food chains.

    Want to win this tasty Baarbarian illustration on a T-shirt? It's easy! The rules: Follow us on Twitter (we're @PopSci) and retweet our This Week in the Future tweet. One of those lucky retweeters will be chosen to receive a custom T-shirt with this week's Baarbarian illustration on it, thus making the winner the envy of friends, coworkers and everyone else with eyes. (Those who would rather not leave things to chance and just pony up some cash for the T-shirt can do that here.) The stories pictured herein:

    And don't forget to check out our other favorite stories of the week:

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    Artist's Conception of Neutron Star CollisionNASA / Dana Berry
    Scientists think a nearby collision of neutron stars could explain the undocumented onslaught of high-energy radiation in the eighth century

    Last year, Japanese scientists found evidence that, in 775 AD, Earth was hit with a sudden blast of high-intensity radiation--a blast carrying about 10,000 times the energy of the atomic bomb dropped on Hiroshima.

    Clearly, something catastrophic had occurred in Earth's cosmic neighborhood, but whatever it was, it apparently went undetected by the 350 million people living on our planet at the time: the historical records contain no mention of strange celestial events that year, catastrophic or otherwise.

    The event is recorded, instead, in the amount of radioactive carbon trapped in the annual growth rings of some of the world's oldest trees. Carbon's key radioactive isotope, carbon-14, forms when energetic particles enter Earth's atmosphere and collide with nitrogen atoms. Since trees take in both carbon-14 and its stable relative, carbon-12, the relative levels of carbon-14 in their growth rings give scientists a way of measuring the amount of high-energy particles entering Earth's atmosphere in a given year. When analyzing two ancient Japanese cedars last year, the scientists found that the amount of carbon-14 present in their 775 AD growth rings was shockingly large.

    It's normal for levels of carbon-14 to fluctuate--they rise and fall on an 11-year cycle with the waxing and waning of solar flares. But for the entire 3,000-year record, there are no other spikes as steep as the one in 775. So what could have caused the massive burst of radiation and the high influx of energetic particles that led to the elevated levels of carbon-14 in the atmosphere? At first, two possibilities seemed the most likely: The radiation either came from an especially intense solar flare or the explosion of a nearby star.

    The scientists ruled out the solar flare hypothesis for two reasons. First, flares of the required magnitude would have sparked an unforgettable display of the northern lights, but, as mentioned, no such phenomenon was recorded. Second--and perhaps more importantly--such flares would also have destroyed the Earth's ozone layer, exposing all of life to harsh radiation and probably setting in motion a mass extinction event.

    On to the next possibility. A nearby supernova would have sent gamma rays flying in all directions. Those rays would have created high-energy particles in our atmosphere, which could then go on to form the carbon-14 present in such abundance in the Japanese cedars. But in order to send out enough gamma rays to do the trick, the supernova would have had to be bigger and brighter than other historical bright spots that were, in fact, documented. Yet, again, no record of a 775 supernova exists.

    And, even if people had somehow missed an exploding star, that star's remnants would still be out there today, giving out a faint glow that could be picked up by telescopes. Scientists have already identified 11 such remnants in our Galactic neighborhood, but none are the right age to have caused the 775 spike.

    When they found that neither solar flares nor supernovae could explain the carbon-14 anomaly they had found, the researchers published their discovery and let the mystery stand.

    But now, a group of researchers from Germany has come up with a plausible cause: a short-duration gamma ray burst, produced by the collision of two nearby neutron stars. Though immensely powerful (we're talking two 10-mile wide boulders, each with the mass of our sun), the collision would only have been visible from Earth for about a day, which could explain why the event wasn't recorded.

    The scientists have identified five neutron stars that could have caused the massive burst, and their step is to take a detailed look at those candidates.

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    Martin Luther King Jr. giving his "I Have a Dream" speech on August 28, 1963Wikimedia Commons
    One creative forensic scientist used just a few specks of metal to debunk the myth of the second shooter theory.

    When the House Select Committee on Assassinations reopened the case of the murder of Martin Luther King Jr. in 1976, some investigators suspected a second shooter may have been involved. Autopsy photos showed specks of metal in King's scalp that seemed to have come from the brass railing in front of him. Because of the angle from which assassin James Earl Ray shot, his bullet could not have hit the railing. Had a second gunman targeted the civil rights leader on April 4, 1968?

    The committee turned to Chicago microscopist Skip Palenik, whose impressive career has also included work on the cases of the Oklahoma City bombing, JonBenet Ramsey, the Unabomber, and the Atlanta child murders. Palenik examined a microscope slide of the metal specks and noticed they had been scratched by the slicing instrument used to mount them. The marks suggested the metal was soft, and therefore more likely to be lead than brass.

    Next, Palenik removed a sample from the slide and cut it in half. He dissolved the first half in solution and then added potassium iodide. The ensuing chemical reaction produced yellow hexagonal plates--a sign of lead iodide. Finally, Palenik used an X-ray spectroscopy detector to obtain an elemental analysis of the other half of the sample. Again, the results pointed to lead.

    Palenik concluded that the specks of metal must have come from a bullet, not the brass railing. There was no second shooter.

    Read the full story in the October 2002 issue of Popular Science.

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  • 01/21/13--07:00: How To Build A Hero
  • Rescue Bot In the DARPA Robotics Challenge, robots will compete in a variety of tasks, including the use of tools to cut through a wall. THOR, a humanoid bot built by a Virginia Tech-led team, has especially powerful legs. It should prove adept at maneuvering over terrain and past obstacles. Nick Kaloterakis
    Humans regularly lose their lives rushing into disaster zones. Now engineers are racing to build robots that can take their place.

    By the end of next year, robots will walk into a disaster zone. They won't roll in on wheels or rumble in on treads. They will walk, striding across rubble, most of them balancing on two legs. Compared with human first responders, the machines will move slowly and halt frequently. But what they lack in speed, they make up for in resilience and disposability. Chemical fires can't sear a robot's lungs, and a lifespan cut short by gamma rays is a logistical snag rather than a tragedy.

    They'll have the mobility to do what robots couldn't at Fukushima, navigating a crisis that unfolds in an environment lousy with doors, stairs, shattered infrastructure, and countless other obstacles. Where previous humanoid bots could barely trundle over the lip of a carpet, these systems will have to climb ladders and slide into vehicles that they themselves drive. And while the ability to turn a doorknob is now cause for celebration even in top-tier robotics labs, these bots will open what doors they can and use power tools to hammer or saw through the ones they can't.

    Because disasters tend to degrade or knock out communication, the surrogates will have a surprising amount of responsibility. Very few, if any, will be tele-operated systems, driven remotely by people using a joystick or wearing sensor gloves. The humanoids will take orders from distant humans, but they'll use their own algorithms to determine how to properly grip a Sawzall, where to start cutting, and for how long.

    The catastrophe the robots will be walking into is, in fact, an obstacle course, built for the two-year-long DARPA Robotics Challenge, which launched last October. At stake is a $2-million prize, awarded to the team whose machine not only scores well in a head-to-head competition this December, but prevails at a second one in 2014. Bots will have to perform eight different tasks, demonstrating both mobility and manipulation skills, that might be required of human first responders.

    "What we've seen in disaster after disaster, from Hurricane Katrina to Fukushima and now to Superstorm Sandy, is that there are often clear limitations to what humans can accomplish in the early stages of a disaster," says Gill Pratt, program manager for the challenge. "DARPA believes that robots can substitute for humans where and when situations are too dangerous."

    The competition rules don't explicitly call for a humanoid design, but the tasks and environment make one a logical choice. From the height of doorknobs to the placement of brake pedals, nearly everything will be positioned and proportioned for creatures that walk upright. The places we care about most in a disaster are where humans live and work­-a robot made in our own image is a natural fit.

    Completing just a few of the competition's tasks would be a remarkable achievement. Nailing all eight of them would be something more. It could mean the birth of the viable humanoid, a machine that's both competent and robust. Such robots could go where mankind has gone before but shouldn't again, striding toward the toxic plume or the reactor in meltdown, into the fresh ruins of the built world. These robots could be heroes./>

    The robot walking toward me certainly looks impressive. Its face is a black, featureless plane, like a riot helmet flipped shut. The rest of its 26.5-pound, five-foot-tall body is white plastic or exposed alloy. If it were standing still, the robot might actually be a bit imposing.

    But CHARLI-2 is moving-and clumsily. It shuffles across the green felt and white tape of a miniature soccer field, its entire body quivering with each short step. It waves as it walks, playing the part of affable celebrity. When the robot runs out of space on the elevated field, it fake scratches its head with a white, fingerless stump of an arm. Thankfully, CHARLI-2 doesn't teeter off the edge. Unable to bend at the waist, it lacks the flexibility to fight its way back to a standing position.

    This is the testing area for the Robotics and Mechanics Laboratory (RoMeLa), which occupies a handful of windowless, basement-level rooms at Virginia Tech. All of RoMeLa's bots-or the ones with legs-take their first steps on this roughly 30-by-30-foot platform, which doubles as a practice field for the yearly RoboCup competition. CHARLI-2 won its division in the robotic soccer tournament in 2012, demonstrating world-class autonomy, agility, and speed for a humanoid.

    Yet its gait tops out at around half a meter per second­-two to three times slower than the average human walking pace. The makers of bipedal robots are a lot like new parents, marveling at their creations' basic ambulation, shaking off each stumble or fall, and framing every setback or success against the most managed of expectations. In this respect, CHARLI-2 is like a proud toddler.

    But its days are already numbered. Its successor stands nearby, waiting to be tested.

    This other robot is not toddlerlike. A work in progress, it's a pair of hulking aluminum legs and a lower torso, the upper body, arms, and head nowhere to be seen. The existing parts, however, radiate strength. Long, bicycle-pump-like actuators run along its legs and fan across what constitutes its lower back. This prototype is the foundation of a machine that will eventually be called THOR, or Tactical Hazardous Operations Robot.

    "CHARLI-2 is old technology," says Dennis Hong, director of RoMeLa. He then points at the unfinished robot. "This is the future, but with a big if-if successful. It does walk," he says, "but will it really be able to do all of the things that DARPA requires?"

    Team THOR comprises researchers from RoMeLa, the University of Pennsylvania, and two commercial robotics firms, with Hong acting as team leader. Though the first trial in the DARPA Robotics Challenge (DRC) isn't until December, the team has already won one of the competition's most coveted prizes-it is among the seven teams accepted into Track A and therefore eligible for up to $4 million for the development of both hardware and software.

    But it's not this achievement that makes Team THOR one of the front-runners. Nor is it RoMeLa's past successes: CHARLI-2 and the lab's smaller humanoid, DARwIn, which also won its size class at RoboCup. Hong's secret weapon is this partial humanoid, which his lab started working on close to a year before the robotics challenge was announced. It's also the prototype for an equally impossible-sounding humanoid project-SAFFiR, or Shipboard Autonomous Fire Fighting Robot.

    SAFFiR is part of a contract from the Office of Naval Research to create a rugged, ultra-capable firefighting robot. Its job is similar to the one proposed by DARPA: It will have to walk into harm's way, navigate where visibility is poor, and maintain its balance in an unstable environment­-in this case, the halls and decks of a ship at sea. But SAFFiR's job differs from THOR's too-it must follow the spoken and gestured commands of a human and either toss fire-suppression canisters into a blaze or hose it down, point-blank, with a backpack-mounted system./>

    SAFFiR provides Hong's team with a clear head start. Because the two programs have overlapping goals, research that has gone into SAFFiR will apply to THOR and vice versa. The same basic engineering, specialized with different tools and capabilities, could wind up doing both jobs. That's the advantage, in theory, of a humanoid: the ability to adapt and accomplish a wide range of tasks, whether it's stepping over the high "knee-knocker" doorsills found on vessels or crawling across shifting rubble at a disaster site on shore.

    Up to this point, Team THOR has focused almost entirely on mobility. Manipulation­-the ability to hold steering wheels and power tools and ladder rungs-will be important down the line, but getting around quickly, and with stability, is the most pressing problem. After all, if a humanoid can't reliably reach its mission, who cares how well it handles an air hammer?

    Bipedal movement has always been the great promise and peril of humanoid robotics. It would allow machines to better maneuver through a range of environments, particularly those built for people. But it's damn hard. It's also damn risky-nearly any fall can be catastrophic. That's why bots like CHARLI-2 take such tentative steps, carefully modulating the exact location of each foot, using a system generally referred to as position control.

    A robot such as CHARLI-2 or Honda's Asimo-a humanoid "helper" that walks, hops, and dances around its own show at Disneyland's Tomorrowland-typically has actuators embedded in its joints that can rotate to bend or straighten each leg. As its walking pace increases, those motors spin faster, but the robot hits a functional speed limit; it can't allow momentum to take over, the way humans do as we break into a run. Their joints are too stiff, and their algorithms require a constant reckoning of the limbs' whereabouts. They don't move like people, with our moment-to-moment oscillation between imbalance and recovery. Robots that use only position control have to know the exact geometry of the terrain beneath them.

    RoMeLa's new robot, by comparison, incorporates force control. It is far more biological in design and function. "The main difference is linear series elastic actuators," Hong says. "Ours is inspired by human anatomy. Our actuators extend and contract like a human muscle."

    Long and cylindrical, the actuators are placed roughly where muscles would go; they act like them too, with titanium springs that provide shock absorption for each step and the elasticity to bounce from one stride to the next. These qualities enable the robot to also use force control: It can turn up the speed of its actuation, working those simulated muscles harder and overriding the algorithmic panic that sets in when position-control software can't perfectly predict each footfall. As a result, it also has more opportunities to recover its balance. Where CHARLI-2 might instantly topple over on stiff legs, this design might try to turn a stumble into a squat. By balancing force and position control, the robot can move with something closer to the loose, improvisational-ultimately more efficient and powerful­-manner of a person.

    The benefits of musclelike actuators and a more adaptable control scheme should be greater speed and stability and an end to the old guard of timid bipedal bots. This robot will take long, terrain-devouring strides, with a literal spring in each step. It will move boldly-because it needs to.

    * * *

    When he first read DARPA's broad agency announcement for the DRC, Nicolaus Radford balked. As the deputy project manager for NASA's Robonaut, a humanoid currently being tested on the International Space Station, he was familiar with what humanoids can and can't do. "It sounded like a six-year-old wrote it," he says. "And then we'll have it drive a car, and then we'll have it climb a ladder and then operate a pump!"

    The DRC is hyperbolic by design, easily the hardest robotics competition in history. That audacity has proved irresistible to engineers. With the glaring exception of Honda-and Asimo could still show up in the unfunded Track D, which has later deadlines-the DRC has attracted the best humanoid robotics labs on the planet. Along with Team THOR, Track A includes two teams from NASA, one from Carnegie Mellon University (the institution that won DARPA's last robotic challenge, a self-driving car race), a company spun out of the University of Tokyo, and a wild-card entry from defense contractor Raytheon.

    Teams in Tracks B and C design only software, but they'll be competing to use robots built by Boston Dynamics (best known for the four-legged BigDog system). This government-provided bot, which Boston Dynamics has based on its PETMAN and Atlas prototypes, is shaping up to be one of the most capable humanoids to date; powerful hydraulic actuators allow it to leap across gaps. The 2014 finals will feature eight robots reflecting the highest overall scores from all tracks, so a showdown between the Boston Dynamics robot and the best of Track A is practically inevitable./>

    What's less certain is whether any of the robots in the final competition can physically complete all eight tasks. First, there are mobility challenges: Robots must travel over debris and through industrial settings. But no humanoid robot has demonstrated the ability to navigate uneven terrain for an extended period, and insect-inspired hexapods, while more stable, move at an achingly slow pace across rocks and rubble. Team THOR sees its actuators as a major advantage here. The Tokyo-based SCHAFT Inc. team has also previously demonstrated an extremely robust humanoid lower body, the HRP3. That robot's rock-solid balance and powerful, liquid-cooled motor drivers could be a huge asset. Both THOR and SCHAFT Inc.'s robot will be well suited to ladder climbing, a task that, according to Hong, can be handled almost entirely by powerful legs, with hands that simply close around the rungs to keep the bot from toppling.

    The manipulation-based tasks, which include opening doors and closing a leaking valve, aren't as risky: A fumbled screwdriver is much less likely than a face-plant to knock a robot out of competition. But for now, none of the entrants has a clear advantage. Radford's team at Johnson Space Center (JSC) is fielding a robot whose core technology is derived in part from Robonaut, which has extremely dexterous five-fingered hands. Robonaut can already handle tools and interfaces used by astronauts during spacewalks, either autonomously or through tele-operation. If JSC's unnamed entry is as nimble as Robonaut and if the team adds a lower body capable of reaching the various destinations in the course, it might perform brilliantly at such tasks as replacing a component and using power tools.

    There's also the possibility that, despite the human-centric challenges, the most versatile robot takes another form entirely. There is a good reason humanoid robots haven't yet walked into our lives: Replicating our own triumphant, two-legged, two-armed physiology with steel and lithium-ion batteries is difficult to do. "Humans are 15 times more energy-efficient at walking than the best humanoid robots," says Radford, "and human fat stores energy at 30 times the density of batteries. That's a significant disadvantage for those systems, right out of the box."

    "Robots don't have to be restrained by our evolution. If we need a camera in some particular place, we put it there."Carnegie Mellon University's Track A entry, the primate-inspired CHIMP, will shift freely from two- to four-limbed movement to better scramble over obstacles. NASA's other Track A team, from its Jet Propulsion Laboratory (JPL), plans to field a version of its four-limbed RoboSimian, a pastiche of biomechatronic diversity whose design and movements resemble sea creatures as much as they do a monkey.

    "While some of the robots in the DARPA Robotics Challenge will be humanoid in form, we know that others will not," says DARPA's Pratt. "It is compatibility with humans that we are after." Victory for CHIMP or RoboSimian could not only torpedo the other team's chances at the $2-million prize, but also fundamentally alter the entire field of humanoid robotics-shifting them to jobs where it's more important to look like a human than to move like one. Why pursue a two-legged hero when a four-legged robot is more competent?

    JPL cherry-picked traits and approaches from a wide swath of nature to build RoboSimian; its tentacled, near-radial symmetry mimics that of a starfish. "Humans have these very derivative structures," says Brett Kennedy, supervisor of the Robotic Vehicles and Manipulators Group at JPL. "Our heads and necks and the way some of the rest of our bodies are laid out, it's about putting specific functions, like sight, where we need them to be. But robots don't have to be restrained by our evolution. If we need a camera in some particular place, we put it there."

    RoboSimian doesn't have a front, rear, or sides. And that ruthlessly efficient design could make it a formidable competitor in ways that won't be obvious until December. Where other robots might range from hilariously awkward to perilously off-balance while getting in and out of a utility vehicle-humanoids would have to pivot and reorient themselves-RoboSimian should be able to simply crab walk into the driver's seat. And having deployed a trio of competent Mars rovers, JPL has learned how to push its robots to perform through harsh, unpredictable environments with limited energy reserves and communication lines. Those systems respond to commands, but with an eight-minute radio lag between Earth and Mars, they must carry out nearly all of them autonomously. For Kennedy and his team, the DRC could be simply another day at the office.

    Hong, who worked with Kennedy years ago on one of the predecessors to RoboSimian, expects stiff comp­­et­ition from every Track A team. But in JPL he sees an existential threat. "Will nonhumanoid forms actually be able to do all those things?" says Hong. "If they can, it's going to completely kill my whole philosophy of why we need humanoids"-to maneuver in a human environment. "But if they can't, it's a good thing for us," he says. "It could prove me completely wrong or prove me completely right."/>

    On the same testing field that CHARLI-2 just crossed, the precursor to both THOR and SAFFiR takes its first steps of the day. There's real menace in this thing: Its actuators whine with each movement, and the blue indicator lights at the apex of its truncated torso are just the right amount of ominous. It walks while tethered to a wheeled carbon-fiber and aluminum gantry (to catch it should it fall) with an amber warning light and bright-red emergency-stop buttons. The arms, which are still being built, will have roughly the same strength as an adult man. But the legs are superhuman. According to the team members from RoMeLa, the legs unexpectedly sheared through aluminum alloy that they placed as a buffer between the heels and ankles. This robot is already more powerful than the team predicted, able to whip its legs forward faster than the eye can track.

    But its movement isn't exactly the stuff of sci-fi nightmares. For all its power and musculature, the prototype is slow. Of course, this is only its third day of walking, and the algorithm it's using is borrowed from CHARLI-2. So while its footstep is longer and its actuators are faster, I'm seeing only a fraction of its eventual speed. RoMeLa hopes to prove that bipedal robots can use energy more economically too; if the linear series elastic actuators perform as expected, they could cut into the efficiency gap between the living and the robotic. A humanoid that burns only five times more energy while walking than a human would be a significant engineering breakthrough.

    Power is always a cause for concern in robotics, but it's particularly problematic during today's test walks. One of the advantages of this humanoid's design is that the actuators can recover a small amount of energy during each step, similar to regenerative braking
    in a hybrid-electric vehicle. But the right knee is acting up. It's recovering too much energy, so the electricity spikes and triggers an automatic shutdown, which causes the robot to tip over. That's the hypothesis, at least. Later, as the robot stands still, actively balancing itself, Hong boosts himself onto the machine. Its 66-pound frame takes his entire body weight without buckling or suffering a crippling power spike. The knee can't be stressed into failing. Its power surges seem to be happening at random.

    First, they'll save lives. Later, they can save the weekend from chores.The RoMeLa team records the data and moves on. There are months, maybe years of troubleshooting ahead. Some of the solutions will be specific to the tasks at hand. But others will apply to the larger enterprise of bots that function in a human world. "The greatest example of a high-risk, high-payoff project is a humanoid," Hong says. "If it can fight a fire, then you can use it for mopping the deck, cooking the food, delivering stuff to you. That's why I call it the Swiss Army knife of robots. If you succeed, you can use it for most everything."

    That's the long-term promise of THOR, SAFFiR, and other humanoid prototypes: that they will lead to initial generations of restricted, million-dollar systems, and as complex components get field-tested and mass-production kicks in, everything will become cheaper. Robots for military and medical missions will have paved the way for consumer models, the ones that assist the aged and disabled, weed gardens, and do laundry. First, they'll save lives. Later, they can save the weekend from chores.

    The initial public test of RoMeLa's engineering will occur this November, when SAFFiR is scheduled to step aboard the U.S.S. Shadwell, a decommissioned World War II-era ship currently docked in Mobile, Alabama. It probably won't spray any hoses or lob any canisters, but rather walk around and get its proverbial sea legs. A month later, THOR will compete in the first of its tasks. Other trials will follow, including a Navy pallet fire and DRC's simulated disaster, both slated for 2014.

    Whatever the results of the DARPA Robotics Challenge-even if it points toward a hybrid robot made up of the best-performing limbs, postures, and control schemes-the real question isn't whether robots will ever be ready for active, meaningful deployment. Just as DARPA's Grand and Urban Challenges accelerated the development of robotic cars and ultimately led to Google's self-driving Priuses, the Robotics Challenge will drive progress toward a truly capable robot. After the competition, it will be only a matter of when they enter society and how.

    It could take a decade or two for the robots to appear in hospitals, helping patients in and out of beds, or at construction sites in the coldest winter months, working the all-robot graveyard shift. But before then, you could see humanlike machines march into a disaster. Perhaps they'll show up online, glimpsed in shaky cameraphone footage. Or maybe you'll see one in person, looming forward through the smoke, its hand reaching for yours.

    Erik Sofge wrote about future space-suit technology for the November 2012 issue of Popular Science. This article appeared in the February issue of the magazine.

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    Physical EducationSam Kaplan
    Amiigo recognizes more than 100 different exercises, and tabulates burned calories with uncanny accuracy.

    Every January, millions of people resolve to get more exercise. Health-club memberships spike as does interest in fitness trackers, which use accelerometers to record activity. The trouble with those devices, though, is that they rely on binary tracking algorithms-moving or not-so they generally can't tell the difference between a steady jog and vacuuming the living room. The Amiigo is the first tracker that can discriminate between exercises, tally reps, and accurately tabulate calories burned.

    The device consists of a shoe clip and a Bluetooth-enabled bracelet, each with a three-axis accelerometer, microcontroller, battery, and enough flash memory to store up to five days' worth of data; the band also contains an infrared blood-oxygen and pulse sensor. When the wearer opens the Amiigo smartphone app, it prompts the bracelet to transmit its data. Algorithms process that data to determine what kind of exercises the wearer has done (barbell curls versus hammer curls, for example) and how much of each one. The Amiigo recognizes more than 100 exercises, but the company plans to release app updates to include more-from sit-ups to bat swings to Frisbee tosses.


    Battery Life: Up to 2 days
    Price: $119 (est.)
    Available: Spring

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    The New Lab Rat Zebrafish (Danio rerio) are one-inch-long freshwater animals that originate in south and southeast Asia. Nature Images/UIG/Getty Images
    Why the tiny zebrafish is becoming many researchers' favorite animal

    The animal facility on the bottom floor of a drab building at Duke University is uncomfortably warm and smells a bit like raw seafood. That's not surprising given what's down there. The space holds a few thousand plastic fish tanks, each home to dozens of zebrafish: one-inch-long, big-eyed vertebrates that are becoming go-to research subjects for many scientists.

    Nico Katsanis, a Duke geneticist who hunts down the causes of rare illnesses, is one of a growing number of researchers choosing to work with zebrafish instead of rodents. Since scientists learned to selectively mutate zebrafish DNA in 1988-giving them the ability to turn the species into models of human diseases-the number of biomedical zebra-fish papers has skyrocketed, from 26 to 2,100 last year. The nonprofit Zebrafish International Resource Center, which sells 2,608 different genetically modified strains to researchers, lists 921 academic labs and companies that use the fish. "The field is on fire," says Leonard Zon of Harvard Medical School. Zon's lab, for example, has used fish models to study skin cancer, blood diseases, and stem cells. Others have created fish with DNA mutations linked to narcolepsy, muscle disorders, and the large head size associated with autism.

    To be sure, rodents still outnumber zebrafish in medical research labs. In 2010, biomedical research papers that used mice or rats were 10 times as common as those that used any other lab animal, and some biological processes-complex brain disorders, say, or anything involving lungs-are best studied in mammals rather than fish. But for most other experiments, from watching tumors develop to screening for new drugs, zebrafish are gaining ground.

    Zebrafish offer three major advantages over rodents. First, they quickly make more zebrafish. A female spawns hundreds of embryos three days after fertilization; mice take three weeks to produce just 10 pups. They are also inexpensive to maintain-about 6.5 cents a day for a tank of a few dozen fish, compared with 90 cents for five mice in a cage. Finally, because larval fish are transparent, researchers can literally watch their organs grow, which makes them especially good for studying problems with organ development.

    Because larval zebrafish are transparent, researchers can literally watch their organs grow.At Duke, Katsanis and his colleagues use zebrafish to more accurately diagnose babies with mysterious health problems, with the goal of eventually finding treatments for them. Although lab rats and mice can be great for common diseases, this kind of research-which looks at exceptionally rare illnesses-would be prohibitively expensive and slow in rodents. The researchers recruit infants with suspected genetic problems from the nearby community. After a team clinician evaluates an infant, the researchers ship a tube of its blood to the Human Genome Sequencing Center at the Baylor College of Medicine. There, machines sequence the child's DNA. If there are mutations (and there almost always are), Katsanis's team can, in a couple of hours, insert the same genetic glitches into a larval zebrafish, making a model of the patient. Then, the researchers use microscopes to observe the fish for about five days, watching for any anatomical defects that develop.

    Since 2010, the Duke team has made zebrafish models for 20 children. It has found "stone-cold causal or very strong leads" for their problems, Katsanis says. For example, they worked with a baby girl who was born with her heart on the wrong side of her body. The researchers replicated the six genetic mutations they suspected were responsible for her syndrome in thousands of zebrafish embryos. Then they screened those fish for a displaced heart. They're not yet finished, but they've already determined that one of the mutations is linked to her condition.

    Within the next five years, researchers will be using zebrafish to find treatments for these rare diseases, Katsanis says. Fish are great for screening many molecules to identify promising drugs for further testing in mammals. Researchers simply put the compound in the water, and the fish absorb it through their skin. Zon's Harvard lab was the first in the world to develop a new drug initially discovered with zebrafish. The researchers tried some 2,500 different molecules on the fish in just four months, one of which dramatically increased the animals' blood-stem-cell counts. After testing the drug in mouse cells, they performed a clinical trial in 2009 with 12 leukemia patients whose blood cells had been wiped out from chemotherapy. The drug quickly boosted blood counts in 10 of them. Since then, Zon has used the zebrafish-screening method to find a potential melanoma drug, which he has so far tested in two people.

    This should be only the beginning of a rush of treatments coming down the zebrafish pipeline. "More labs are building aquariums," Katsanis says. "The number that use zebrafish is going up hyper-exponentially."

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    Obama's inaugural address

    President Obama vowed to tackle climate change in his second inaugural address today.

    "We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations," he said. "Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms. The path towards sustainable energy sources will be long and sometimes difficult. But America cannot resist this transition; we must lead it."

    This isn't the first time Obama has pledged to prioritize climate change. After winning reelection in November, he conceded that he had limited success combating global warming in his first term, but insisted he would take personal charge of the issue in his second term. We here at Popular Science have some ideas for how he can do that.

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    Cushion The BlowEPA/Piroschka van de Wouw
    Testing airbags that are better for bikers--even if the crashes still look rough on the dummies.

    In the United States, only 1 percent of trips are made by bicycle. In the Netherlands, which has only 1/18 of the U.S.'s population, that number is close to 26 percent. With so many bikes on the road, Dutch company TNO is working on a car airbag that deploys outside the vehicle to reduce bicyclist injuries. Upon impact, the airbag, housed under the hood, inflates to cover parts of the windshield and cushion a biker. In tests last November, engineers drove a track-guided car into a dummy on a bike at 25 mph, the average speed of a crash. Accelerometers in the dummy's head and neck and pressure sensors embedded in its limbs indicated brain damage and broken bones. Dummies in collisions with the airbag had fewer and less severe injuries up to 45 percent of the time.

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    Mobius HouseUniverse Architecture
    12,000 square feet of habitable Mobius strip.

    The architects at Amsterdam-based Universe Architecture have proposed some M.C. Escher-like buildings before. (See: this plan for a building that's "both small and big.") But architect Janjaap Ruijssenaars wants to go one step farther with a building that twists in on itself, never beginning or ending at all. To make that happen, he's enlisting the world's biggest 3-D printer.

    Instead of creating a flat strip of material and bending it into a shape like a Mobius strip, the gigantic D-Shape printer will make pieces of the 12,000-square-foot building, spitting out 6-by-9-meter section that will eventually be assembled into the full building. (The printer's inventors want to use it to print houses on the moon eventually, so this is a nice warmup.) A mixture of sand and a binding agent will make the frames of the structure, and each frame will be filled with fiberglass and concrete. Steel and glass will make up the facade.

    The project could take about 18 months to complete, with the printer working for up to half a year. As for who's buying it: Ruijssenaars told AFP that a Brazilian national park has shown interest in the building, which would cost $5.3 million to build. But it could still be used as a museum, or even as a home for some very lucky, math-minded millionaire.

    [Inhabitat, AFP]

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    A Good Food Photovia Popular Photography

    The New York Times ran an article today about restaurants that ban customers from taking photos of their food. Sparked lots of discussion! Our friends over at Popular Photography put up a response post that addresses how to take photos of your food with two main goals in mind: to take better photos (no flash, people), and to take photos without disturbing other diners. It's a great little guide. Read it here.

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    DARPA's Phoenix: On Orbit Satellite SalvageDARPA
    The Phoenix program is building a robot that can repurpose dead satellites into new ones in space.

    DARPA's vision for scavenging and salvaging dead satellites in orbit continues its trudge toward technologic feasibility. DARPA launched its Phoenix initiative in summer of last year hoping to cobble together a robot capable of intercepting, dismantling, and rebuilding defunct satellites even as they whip through space some 22,000 miles above the Earth. It's a tall order, requiring all kinds of capabilities that are less-than-fully mature, things like robotic autonomy/artificial intelligence, machine vision, and on-orbit satellite refueling. But if a new video released by DARPA is any indication, work on the Phoenix satellite scavenger is progressing.

    That's not to say a vehicle launch is in the immediate offing, but the video above--illustrated by an animation of how each technology piece would work within the larger concept--shows piece by piece how the project is moving forward. And there are a lot of pieces to consider.

    Phoenix will need to be able to rendezvous in space with newly launched satellites, on which smaller "satlets" will hitch rides into orbit. Phoenix will then remove those satlets (without damaging whatever multimillion-dollar satellite they are riding on) and carry them to dead satellites in other orbits. It will then attach the new satlet--which carries the electronic brains of a new satellite--to the dead satellite's antenna before severing the antenna from its now-defunct satellite body. The new satlet now has a perfectly good piece of legacy hardware it can use to communicate with ground stations or other satellites, and after placing it in the proper orbit the Phoenix vehicle can move on to its next salvage job.

    None of that is going to be easy, but DARPA clearly isn't deterred by the challenge. Another Proposer's Day is slated for Feb. 8 in which the agency will ask for even more technologies related to the vehicles software, hardware, and satlet launch capabilities.


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    Four-Strand DNA 'G-Quadruplex'JEAN-PAUL RODRIGUEZ via Nature
    We've seen 'G-quadruplex structures' before, but a new study shows they are much more prevalent in our genomes than we thought.

    The above is a digital model of DNA, but it's probably not the DNA you're familiar with. The double-helix structure of DNA and RNA--two strings of nucleic acids spiraling around each other and held together by complementary base pairs--is both nearly universally recognized and central to its role as the fundamental vehicles for cell function. But it turns out that a square shaped, four-strand DNA structure (like the one above) is likely more common in our genomes than we previously thought, and that could have important implications for biology.

    Four-strand DNA--or "G-quadruplex structures" (the G is for the base guanine)--is nothing new to genetic scientists. It can be easily conjured in the lab via guanine-rich strands of synthetic DNA, for instance, and it has long been thought to occasionally form naturally in biological cells. But a new study published online at the journal Nature Chemistry and conducted by University of Cambridge researcher Shankar Balasubramanian suggests that G-quadruplex structures are more common in natural genomes than we thought, and that they may carry out some important genetic business.

    This has particular importance in the field of cancer research. Some researchers have previously suggested that these quadruplexes can be found in places along the genome where gene regulation occurs. Errors in gene regulation are, of course, one of the root causes of the kinds of abnormal cells that lead to cancerous cell replication. So the Cambridge researchers engineered an antibody designed specifically to seek out and bind to G-quadruplex structures while steering clear of double-helical structures. When introduced to human cells, the antibody bound itself to several sites along the chromosomal chain--not just in the few where the researchers expected it to--reinforcing the idea that G-quadruplex structures are more prevalent in more places than originally thought.

    If researchers can figure out all the places where these structures are forming along the genome, they may be able to zero in on the places where genetic ailments like cancer get their starts and try to mitigate that process.


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    DIY flash reflector, 1969Popular Science archives
    In honor of National Pie Day, why don't you try one of these fun crafts from the Popular Science archives? Use a pie tin to make a jet engine, a telescope, or a lovely chandelier.

    Today is National Pie Day (the less-cool cousin of March 14's Pi Day) and, to celebrate, we've compiled 10 fun and easy pie-tin crafts from the Popular Science archives.

    What do a hipster chandelier, an amateur telescope, and a living-room jet engine have in common? You can make each one with an ordinary pie tin!

    Click here to enter the gallery

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    The Fallen Junior Seau's suicide in 2012 heightened the controversy around head trauma in athletes. Colts receiver Austin Collie [above] received three game-ending concussions in 2010 before he was benched for the season. Doug Pensinger/Getty Images
    UCLA researchers discover brain damage that previously couldn't be seen until after players died--a finding that could help save players' lives.

    Researchers at UCLA have announced a major finding that could save the lives of football players and other contact-sports athletes who've suffered countless traumatic brain injuries.

    In the war against head trauma in football, one of the most vexing problems has been how to identify and treat a condition known as Chronic Traumatic Encephalopathy. CTE is a form of brain damage that's caused by multiple blows to the head and is believed to be the culprit in the high-profile suicides of former players such as Junior Seau, of the San Diego Chargers, and Dave Duerson, of the Chicago Bears. Until now, doctors haven't been able to diagnose CTE in living people; they've had to dissect players' brains postmortem to spot the telltale signs.

    But the authors of a new study published in The American Journal of Geriatric Psychiatry claim they've been able to spot CTE in living players for the first time. The researchers used a special kind of PET (positron emission tomography) scan to spot signs of the disease in five former players whose ages ranged from 45 to 73, and who played five different positions: quarterback, linebacker, guard, defensive lineman, and center.

    The brain images showed heavy deposits of a protein called tau, which accumulates along neural pathways that get damaged as a result of repetitive blows. As the tau builds up over time in a player's brain, it essentially creates road blocks that prevent brain signals from traveling where they need to. The result is memory loss, lack of impulse control, aggression, and depression. And ultimately, doctors believe, those symptoms can lead a man to suicide.

    The implications of the finding are big: Robert Cantu, an adviser to the NFL and co-director of the Center for the Study of Traumatic Encephelopathy at Boston University, called the finding a "Holy Grail." Cantu's lab has been at the forefront of CTE research thus far, but much of its work has been limited to studying brains donated by the families of deceased former players. One of the biggest frustrations for people in Cantu's field has been the guesswork of diagnosis. That could all change if the UCLA study holds true. Being able to spot the disease before it's too late could open up treatment options. If the disease were spotted in an active player, it could inform a decision about retiring. A negative screening for CTE could even be a prerequisite for playing a contact sport: If you have enough signs the disease, you're out.

    The UCLA researchers caution that their findings are based on an extremely small sample size--five players--and that further research will have to corroborate their work. In the meantime, another question lingers: How to mitigate the force of those hits in the first place and stop the brain damage before it starts.

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    A Polymer For Turning Swimming Pools To Jelly Like Vonnegut's Ice-Nine, but gelatinous consequences. Left: The polymer structure captured be atomic force microscope. Right: The polymer's helical backbone and tails that connect to other polymer strands. A. ROWAN ET AL / RADBOUD UNIVERSITY OF NIJMEGEN via Nature
    So... how can we weaponize this?

    Dutch researchers have developed a gel-forming polymer so effective that a kilogram of the stuff sprinkled across an Olympic sized swimming pool would turn the entire thing to jelly. At least, that's how they describe the properties of polyisocyanide polymer, which they've just revealed to the world in the journal Nature. Materials scientist Alan Rowan at the University of Nijmegen in the Netherlands calls it the best gel-forming polymer in the world, "an order of magnitude better than anything else." All you have to do is add a little heat.

    This is cool on a number of levels. First of all, though the researchers have not yet experimented with a real Olympic swimming pool, the ability to rapidly turn large bodies of water into gelatin is sure to have major impacts in the disciplines of both cocktail party tricks and teenage petty vandalism. But from a materials science standpoint the polymer really is a breakthrough, exhibiting properties that are pretty strange and exciting, at least if you're the kind of person who gets excited by material properties.

    For one, most gels form upon cooling, not heating (think: Jell-O), which opens the door to some interesting potential applications. Further, polyisocyanide polymer is the first to demonstrate a rigidity that matches that found in biological polymers. Almost all naturally occuring biopolymers possess a kind of inherent rigidity that synthetic polymers simply lack, but Rowan's polymer is an exception. Its polymer strands consist of a helical backbone surrounded by short peptide arms sticking out from the sides. Each of these peptide arms is in turn tipped with a long tail of repeating carbon and oxygen chains that are nicely suited to grabbing water molecules, making it quite soluble.

    But once dissolved, heating it causes the tails to push water molecules away and link up to other tails belonging to other polymer strands, rapidly building a polymer structure with the water trapped in between. The result is a gel that forms within seconds once the water/polymer mix hits a certain temperature (it's unclear exactly what that temperature is, and it may vary depending on external factors).

    Beyond Olympic-pool-sized servings of gelatin, such a fast-forming gelatin mixture could be used to quickly plug open wounds--simply pour in the cold mixture in and let body temperature stiffen it up. This polymer bandage could then be later removed with nothing but an ice pack.


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    Snowball FightVintage Images/Getty Images
    The key is in surface moisture.

    Anyone who's tried to make a snowball understands the need for snow of just the right consistency. Start with powdery snow and a ball will fall apart. Start with slushy snow and it will turn into a hunk of ice. The key, then, to a killer snowball is to find snow that's in the perfect sticky state.

    According to Jordy Hendrikx, director of the Snow and Avalanche Laboratory at Montana State University, snow at subfreezing temperatures contains no liquid water. When the grains of ice begin to melt, each one forms a wet meniscus. The menisci work as snowball glue, he says, mingling and then refreezing.

    Scott Sandford, a senior astrochemist for NASA, points out that extreme pressure could also play a part in making snowballs. "If you squeeze water ice hard enough, it will melt," he explains. Packing snow into a ball could force some of it across that pressure threshold, making it liquefy and then refreeze. To get that kind of pressure, though, you'd need to be in space or a lab. In a casual snowball fight, surface moisture is still the most important factor. So what about the old theory that bare hands make the best snowballs? "It doesn't make any difference," Sandford says. "You're better off with gloves, so your hands don't get cold and numb."

    Have a burning science question you'd like to see answered in our FYI section? Email it to

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    Solar Corona This is one of the highest-resolution images ever taken of the solar corona, or outer atmosphere. It was captured by NASA's High Resolution Coronal Imager, Hi-C, in the ultraviolet wavelength of 19.3 nanometers. Solar magnetic fields are constantly warping, twisting, and colliding in bursts of energy. Taken together, those energy bursts can boost the temperature of the corona to 7 million degrees Fahrenheit when the Sun is particularly active. NASA/CfA
    A flying telescope saw "magnetic braids" at a resolution of 0.2 arcseconds - about the size of a dime seen from 10 miles away.

    People like to joke, when it's really hot, that it's "like the surface of the sun or something." People should not say that. They should say it's like the atmosphere of the sun, which is way hotter. The solar corona is around 2 to 4 million degrees Fahrenheit, and it gets hotter as you move farther away from the surface. This bizarre fact has stymied scientists for decades, but now they have some answers--all thanks to a tiny telescope that flew beyond Earth's atmosphere for just a few minutes.

    NASA's High Resolution Coronal Imager, or Hi-C, captured the highest-resolution images ever taken of the solar corona during its brief journey last summer. It flew high into the Earth's atmosphere aboard a sounding rocket, a type that is used for experiments, and then it parachuted back to Earth for recovery. This was much cheaper than launching a satellite; the whole mission was just $5 million. It was not without new technological advances, however--Hi-C's 9.5-inch mirrors are "the finest pieces of glass ever fabricated for solar astrophysics," in the words of heliophysicist Jonathan Cirtain, the mission's principal investigator.

    Hi-C, which weighs 464 pounds and is 6 feet long, took a 10-minute ride on a sounding rocket in July. Over five minutes of data collection, it took 165 images of the coronasphere. It found evidence of a powerful force called magnetic reconnection, which pumps vast amounts of energy into the corona and heats it up.

    Our star is powered by magnetic fields--those arcing loops you see on images from SDO and other solar observatories are the result of these fields. Plasma flows along the fields and illuminates them. Images from Hi-C showed where these fields were braided tightly together like rope. When they relax and straighten out, they release energy, which helps drive temperatures up to a toasty 7 million degrees F.

    Hi-C was so effective because it could see this action in superfine detail. The Harvard-Smithsonian Center for Astrophysics, home of some of the researchers who published these findings, explains that Hi-C's telescope had a resolution of just 0.2 arcseconds. An arcsecond is a measurement of a piece of sky, and it's tiny--just two-tenths of an arcsecond is roughly the size of a dime seen from 10 miles away. This meant astronomers could see areas just 100 miles across on the face of the sun. (The star is 865,000 miles in diameter.)

    The Hi-C paper publishes this week in Nature, but astronomers are still analyzing more data. Eventually, they hope to build a satellite that will observe the sun the way Hi-C did, according to CfA astronomer Leon Golub. ""We learned so much in just five minutes. Imagine what we could learn by watching the sun 24/7 with this telescope," he said.

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    Condoms Are Still FunWikimedia Commons
    Well, duh.

    Good news, everyone: safe sex is still fun sex. And now we have a published study to prove it. (In case you needed that confirmation, for some reason.)

    Researchers from Indiana University crunched the data from the 2009 National Survey of Sexual Health and Behavior, examining the most recent sexual "event" for adults ages 18 to 59. The people who used condoms and lubricant during their "event" rated the experience "as highly arousing and pleasurable with few differences based on condom or lubricant use." The team's results are published in the Journal of Sexual Medicine.

    And a bonus, sort-of-obvious subpoint emerged, too: more than twice as many men as women knew the condom was lubricated or what material it was made out of. (Because men are more likely to purchase and apply the condom, the researchers suggest.)

    Hopefully all of that wasn't stopping you from practicing safe sex. But if you needed a data-driven, scientific push, you have no excuse now.

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    Vine App ScreenshotsDan Nosowitz
    It's a GIF. Or a video? It's kinda fun, anyway. Get ready to see looped, lightly edited video in your Twitter feed.

    Twitter just launched Vine, a new standalone app for the iPhone and iPod Touch that also integrates into your Twitter timeline. It's the latest in a long line of "the next Instagram" attempts--not too different from Cinemagram, an app which had a mild and short-lived vogue last year and allowed you to make short GIFs.

    But instead of a GIF, a "Vine" is a short, 6-second-maximum looping video, which, unlike Snapchat or Poke creations, does not self-delete after a few seconds. You simply touch your finger to the screen to start recording, and lift it to stop recording. Easy! The major advantages to Vine are thus: it includes audio; it allows limited editing (you can tap and hold the app multiple times in one Vine, allowing a string of short clips), and it's embedded in Tweets just like an image. When you scroll through Tweets in an official Twitter feed, you'll see the Vine right there.

    But Vine also has some kind of confusing disadvantages. Vines do embed in tweets, which means you can embed an entire tweet in a website, but part of the beauty of GIFs is that they're supported by virtually every application that supports any kind of images--except Twitter. Vines won't paste in chat rooms or emails or most other places, but they will embed on Twitter.

    The app also has a few problems--people are having issues downloading and running it (it seems to force close for some people, though I've had no trouble with mine). It also does not support the iPhone's front camera, which makes no sense. But more importantly, it's just one more social network--you have to add friends manually for them to show up in your Vine app's feed (for some reason it doesn't pull in friends from your Twitter feed, though it has access to that), and remember to check it, and remember to make a Vine instead of a Twitter picture or Instagram or Snapchat or, Christ, there are so many of these now.

    I've liked some of the Vines I've seen, but it doesn't seem to me that the advantages over a GIF make up for the negatives. But who knows! Maybe it'll catch on. You can download it here, for free.

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