- Robot Nurses Are Less Weird When They Don’t Talk
- Oldest Female Elephants Have Best Memory
- 115-Year-Old Medical X-Ray Machine Comes Back to Life
- Japan Struggles to Control Quake-Damaged Nuke Plant
- NASA Considers Shooting Space Junk With Lasers
- Midway’s Albatrosses Survive the Tsunami
Posted: 16 Mar 2011 11:05 AM PDT
Medical patients would probably be ok with semi-autonomous robots tending to them, but only if the robots don't talk to them first.
Robotics researchers tested whether a verbal explanation from a robot would help people feel more comfortable with the robot administering care, but found that precisely the opposite was true.
"Robotics has mostly been about teaching machines how to not touch people, walls, chairs and other objects," said robotics researcher Tiffany Chen of the Georgia Institute of Technology, part of a team that presented the study March 9 at a human-robot interaction conference in Switzerland. "This is one of the first steps toward understanding what happens when robots touch people."
Most semi-autonomous robots do precise or dangerous grunt work, such as assemble automobiles or help neutralize improvised bombs. Now robots have advanced to the point that they are ready to take on more delicate work, such as assisting nurses. But the bots may not be as accepted in a hospital as they are in a factory.
"If we want robots to be successful at health care, we're going to need to think about how do we make those robots communicate their intention and how do people interpret the intentions of the robots," biomedical engineer Charlie Kemp of the Georgia Institute of Technology said in a video about the work.
Kemp and his team programmed a robot named Cody to gently wipe its hand across volunteers' arms, as if cleaning them, or administer a soothing touch. In some trials, Cody explained to people with a synthetic female voice what it was about to do, and in others it didn't say anything until after touching the participants.
People generally didn't mind being touched by Cody overall, but were less comfortable with the robot when it spoke to them beforehand. And participants were more accepting of a potentially necessary medical touch than an attempt at a soothing touch by the robot.
"The results of the voice timing surprised us. We thought people would want to be told something like 'I'm going to clean you,' and then the robot cleans. But the opposite was true," Chen said.
Image: Cody the robot touches one of 56 study participants. (Georgia Tech)
Posted: 16 Mar 2011 10:00 AM PDT
Not to cause dinner table shouting or new excesses of political punditry — but in a test of a particular leadership skill among elephants, age and experience really did trump youth and beauty.
Elephant matriarchs 60 years of age or older tended to assess threats in a simulated crisis more accurately than younger matriarchs did, says Karen McComb of the University of Sussex in Brighton, England. When researchers played recordings of various lion roars, elephant groups with older matriarchs grew especially defensive at the sound of male cats. Younger matriarchs' families underreacted, McComb and her colleagues report in an upcoming Proceedings of the Royal Society of London B.
The older females have it right, McComb says. Male lions rarely attack an elephant, but when they do, they can be especially deadly: A single male can bring down an elephant calf.
Studying leadership among animals has become an active research area. "People have become intrigued by some of the parallels between the sorts of characteristics that seem to define a leader in animals and in humans," McComb says.
The new elephant approach "is definitely novel," says psychologist Mark van Vugt of VU University Amsterdam, who studies the evolution of leadership. The new paper extends a general observation — that older individuals show more leadership in tasks involving specialized knowledge — into situations involving threats.
"There is an interesting trade-off here, which certainly applies to humans and maybe elephants as well," van Vugt says. "The group might want a young, fit and aggressive leader to defend the group — the Schwarzenegger type — but at the same time might want an older, more experienced leader — the Merkel type — to make an accurate assessment of the dangers in the situation."
Among elephants, family groups made up of a matriarch and a dozen or so of her female kin and their youngsters can stay together for decades. The oldest elephant provides leadership, but "she doesn't lead by being heavy-handed," McComb says. She may not walk at the front of the group when they commute to their morning waterhole, but the other elephants pay attention to where she goes and how she reacts.
To test for crisis leadership among elephants, McComb and her colleagues played lion calls to 39 elephant families in Kenya's Amboseli National Park. Researchers compared reactions to roars from one lion versus three lions. All the matriarchs correctly perceived that three was more worrisome than one. "It was quite a revelation" says coauthor Graeme Shannon cq, also of Sussex. Before this test, evidence had been unclear about how widespread numerical threat assessment would be. The older matriarchs managed another layer of awareness though, by judging male lions more threatening than females.
"If you remove these older individuals, you're going to have a much bigger impact than you realize because they're repositories of ecological knowledge and also of social knowledge," McComb says. Poachers, targeting the big old elephants, pose a particular menace to the species.
Image: Graeme Shannon
Video: Elephants react to what they perceive as a very dangerous lion during a test of threat assessment. (Karen McComb/Vimeo)
Posted: 16 Mar 2011 09:02 AM PDT
A team of physicists, engineers and radiologists recently revived a first-generation X-ray device that had been collecting dust in a Dutch warehouse. The antique machine still sparked and glowed like a prop in an old science fiction movie, and used thousands of times more radiation than its modern counterparts to make an image.
The old machine was originally built in 1896 by two scientists in Maastricht, the Netherlands, just weeks after German physicist Wilhelm Conrad Röntgen reported his discovery of X-rays — an achievement that won him the first-ever Nobel Prize in physics and sparked a rash of copycat experiments.
H.J. Hoffmans, a physicist and high school director in Maastricht, and L. Th. van Kleef, director of a local hospital, assembled the system from equipment already on hand at Hoffmans' high school and used it to take some of the first photographs of human bones through the skin, including in van Kleef's 21-year-old daughter's hand.
Since then, X-rays, which are the right wavelength to tunnel through muscle but are slowed by denser bones, have become almost synonymous with medical imaging. But most of those first X-ray systems were lost to history. Because the techniques and technology to measure radiation doses weren't invented until decades after the first X-ray machines came about, no one knows exactly how powerful those systems were.
"There's a gap in knowledge with respect to these old machines," said medical physicist Gerrit Kemerink of the Maastricht University Medical Center. "By the time they could measure the properties, these machines were long gone."
About a year ago, when Kemerink's colleague at the hospital dug Hoffmans and van Kleef's aging machine out of storage to use in a local TV program on the history of health care in the region, Kemerink grew curious about what the gadget could do. In a paper published online in Radiology, Kemerink reports the first-ever diagnostics on a first generation X-ray device.
"I decided to try to do some measurements on this equipment, because nobody ever did," he said.
Aside from a modern car battery and some wires, the researchers used only the original equipment, including an iron cylinder wrapped in wire to transfer electrical energy from one circuit to another and a glass bulb with metal electrodes at each end.
The glass bulb, technically called a Crookes tube, contained a tiny bit of air, about a millionth of normal air pressure. When the researchers placed a high voltage over the tube, the electrons in the gas were ripped from their atoms and zipped across the tube from one electrode to the other.
Electrons naturally emit X-rays when they speed up, slow down or change direction. When the electrons hit the glass walls of the Crookes tube, they came to a screeching halt, giving off a ghostly green glow and invisible X-rays.
The machine took some coaxing before it would glow, Kemerink said. The team fiddled with it for a solid half hour with no success.
"At the time we were thinking that it would be possible that we would not succeed with our plans," he said. "But then suddenly something happened, and we were in business."
Kemerink now thinks that the gas pressure inside the bulb was too high for the electrons to travel through the tube. But then a bit of aluminum on one of the electrodes melted, sucking gases from inside the bulb.
"It's a technique used today to improve your vacuum: Evaporate metal and trap some gases," he said. "That is what happened, although we did not do it on purpose."
Images of a hand specimen from an 86-year-old woman taken with the old X-ray machine (left) and a modern one (right). The exposure for the 1896 system took 21 minutes.
The researchers used standard hospital radiation-detecting devices to measure the amount of X-rays needed to take an image of the bones in a human hand (this time, a specimen borrowed from the anatomy department, not from a living person). The old machine took surprisingly clear pictures, but gave the skin a dose of radiation 1,500 times greater than the same image would require today. An exposure that takes 21 milliseconds (thousandths of a second) on a modern machine took up to 90 minutes on the antique system.
"It was interesting that the image quality was actually that good," said radiologist Tom Beck of Quantum Medical Metrics, a company that researches ways to get structural information from bones using medical imaging. "That was surprising."
This first-generation system did not produce enough radiation to cause health problems, although Kemerink and colleagues all stood behind a transparent lead shield whenever the machine was on, just in case. But X-ray devices got steadily more powerful shortly after Hoffmans and van Kleef built their machine, and technicians didn't always take precautions against harmful radiation.
"Within weeks, people reported skin burns, a little bit later even much worse things," like blisters and sores that wouldn't heal, Kemerink said. Some workers had to have fingers or even a whole arm amputated. "Many of these early X-ray workers developed cancer, and many of them died untimely, very young."
The difference in danger highlights how far X-rays have come, he said. In another study published online Feb. 15 in Insights into Imaging, Kemerink and colleagues showed that, with all the shielding used today, modern X-ray workers feel less radiation in the hospital than they do at home.
"There's so much to say about how far we've come," Kemerink said. "These machines when they started they were extremely dangerous. Now in all those years, they improved technology so far that you can really neglect what you are receiving when you do normal X-ray scans."
Working with the machine was "very special, I must say," Kemerink added. The air smelled of ozone, the interruptor buzzed, lightning crackled in the spark gap, and the insides of the human body showed themselves.
"Our experience with this machine," the researchers wrote, "was, even today, little less than magical."
Video: Maastricht University Medical Center. Images: Courtesy Gerrit Kemerink.
Posted: 15 Mar 2011 10:08 AM PDT
In the aftermath of the earthquake and tsunami that struck northeastern Japan on March 11, engineers are flooding three nuclear reactors with seawater in an effort to cool their radioactive cores and to prevent all their nuclear fuel from melting down. Explosions have been recorded at two of the reactors, but do not seem to have breached the crucial inner containment vessels.
The grimmest situation is at the final reactor, where water stopped flowing temporarily March 14, exposing the fuel rather than cooling it. Much now depends on the containment vessels that shield the highly radioactive reactor cores. Even a full meltdown does not necessarily mean that the reactors will release large amounts of radioactive material — as long as the vessels remain intact.
Officials are closely monitoring several reactors at the Fukushima facility, on the northeastern coast of Japan near where the magnitude-8.9 earthquake hit. There are two clusters of reactors at Fukushima. The Daiichi cluster includes six boiling-water reactors, all of which came online in the 1970s.
In the boiling-water design, nuclear reactions in the core generate heat and cause water to boil, which makes steam to drive turbines and produce electricity. Together, the six Daiichi reactors produced 4.7 gigawatts of power before the accident.
The largest nuclear facility in the United States, the Palo Verde facility in Arizona, has a capacity of 3.7 gigawatts and serves roughly 4 million people. With 54 nuclear facilities operating before the accident, Japan is the third-largest producer of nuclear energy after France and the United States.
Most nuclear reactors use uranium as their primary fuel, although Unit 3 at Daiichi uses a mix that includes plutonium. Pellets of enriched fuel are encased inside long, narrow tubes made of an alloy containing the metal zirconium. These tubes, known as fuel rods, are spaced in an array with water flowing between them. Several hundred of these packages are then put together to create the core of the nuclear reactor.
The uranium-235 isotope, which contains 92 protons and 143 neutrons, is inherently unstable, tending to split (or fission) into lighter elements. Such spontaneous fission releases stray neutrons. When one of those neutrons hits a uranium atom, it also initiates fission into lighter elements, releasing more neutrons. Those neutrons can then go on to hit other uranium atoms in the fuel pellets, causing a chain reaction.
A reactor is said to have "gone critical" when it has this self-sustaining reaction underway in its core. As long as operators keep variables such as temperature and the flux of neutrons in hand, the fission will continue at a controlled pace.
But the reactor core requires water to cool things down and moderate the flux of neutrons coming from the fissioning uranium. Without water things can heat up quickly — both the temperature and the rate of fission within the reactor core.
According to Japan's Nuclear and Industrial Safety Agency, the earthquake knocked out power to the Daiichi facility. "Control rods" to slow the rate of fissioning dropped automatically in between the fuel rods.
Control rods are usually attached to magnets and hang above the core, and if an earthquake strikes they automatically detach, drop down and help shutter the reaction, says Ron Hart, a retired professor of nuclear engineering from Texas A&M University in College Station. The control rods absorb neutrons to prevent the reaction with uranium that causes fission. But even with the control rods in place, the reactor still produces heat at a small fraction of its full power, because of the decay products of the uranium fission.
As planned, backup diesel generators kicked in after the monster earthquake and continued to pump water in to cool the reactor cores. But when a tsunami swept across the Japanese coast about an hour later, the wave disabled the backup generators. The next backup system then kicked in: battery-powered pumps.
But the battery pumps could not keep up with the residual heat still coming from the cores of several Daiichi reactors. Excess heat caused steam to build up in the system, which operators eventually vented into the environment along with low levels of radioactive elements like cesium and iodine.
At the same time, though, hydrogen gas had apparently built up within the core, likely created by chemical reactions of the hot zirconium rods with water. The explosions at Daiichi Units 1 and 3 were likely caused by that hydrogen igniting.
Potentially far more serious is Unit 2, where pumps failed for a time on March 14, causing the water level to expose the fuel rods almost completely. If the rods melt entirely, they could drop their fuel pellets to the bottom of the reactor core. The pellets could then generate enough heat to melt through the bottom of the steel containment vessel.
"Once that happens the ability to contain the accident is greatly reduced, because the core is liquefied and spreads across the floor," says Edwin Lyman, a physicist with the Union of Concerned Scientists in Washington, D.C., a group that has long voiced concerns about the risks of nuclear power.
In the 1986 nuclear accident at Chernobyl in Ukraine, the melting core did not have the heavy shielding of a containment vessel, as the reactors in Japan do. The Chernobyl core exploded, blowing radioactive materials over large parts of western Asia and Europe and causing an ecological and public health castastrophe.
In the 1979 Three Mile Island accident in Pennsylvania, the reactor's core suffered a partial meltdown but its pressure vessel was not breached, and only low levels of radioactive material made it into the environment. The Daiichi incidents, at least so far, may be far more like Three Mile Island than like Chernobyl.
On the international scale used by experts to rank nuclear incidents, Chernobyl ranked as a "major accident" or 7, the highest on the scale. Three Mile Island was a 5, an "accident with wider consequences." Japanese officials have said they regard the Fukushima incident as a 4, an "accident with local consequences."
Operators at Daiichi have flooded all three reactors with seawater mixed with boric acid. The boron in the boric acid absorbs neutrons and helps keep them from bouncing around and triggering further fission in the fuel rods. Salts in the seawater will, however, permanently corrode the reactor cores and render them unusable in the future.
Hart says it will probably take several weeks of keeping the cores underwater to cool them enough to stop the fission completely. At that point, operators can carefully extract the cores and take them to a containment facility to assess damage, take them apart and dispose of them.
Image: DigitalGlobe [high-resolution version]
Posted: 15 Mar 2011 09:32 AM PDT
The growing cloud of space junk surrounding the Earth is a hazard to spaceflight, and will only get worse as large pieces of debris collide and fragment. NASA space scientists have hit on a new way to manage the mess: Use mid-powered lasers to nudge space junk off collision courses.
The U.S. military currently tracks about 20,000 pieces of junk in low-Earth orbit, most of which are discarded bits of spacecraft or debris from collisions in orbit.
The atmosphere naturally drags a portion of this refuse down to Earth every year. But in 1978, NASA astronomer Don Kessler predicted a doomsday scenario: As collisions drive up the debris, we'll hit a point where the amount of trash is growing faster than it can fall out of the sky. The Earth will end up with a permanent junk belt that could make space too dangerous to fly in, a situation now called "Kessler syndrome."
Low-Earth orbit has already seen some scary smashes and near-misses, including the collision of two communications satellites in 2009. Fragments from that collision nearly hit the International Space Station a few months later. Some models found that the runaway Kessler syndrome is probably already underway at certain orbit elevations.
"There's not a lot of argument that this is going to screw us if we don't do something," said NASA engineer Creon Levit. "Right now it's at the tipping point … and it just keeps getting worse."
In a paper submitted to Advances in Space Research and posted to the preprint server arXiv.org, a team led by NASA space scientist James Mason suggests a novel way to cope: Instead of dragging space junk down to Earth, just make sure the collisions stop.
"If you stop that cascade, the beauty of that is that natural atmospheric drag can take its natural course and start taking things down," said William Marshall, a space scientist at NASA and coauthor of the new study. "It gives the environment an opportunity to clean itself up."
Simply keeping new fragments from forming can make a big difference for orbital safety, Levit said. Because objects with more surface area feel more drag, the atmosphere pulls down the lightest, flattest fragments of space junk first. When big pieces of debris break up into smaller ones, the pieces become harder and harder to remove.
Worse, the pieces left behind are often the most dangerous: small, dense things like bolts.
"If one collides with a satellite or another piece of debris at the not-unreasonable relative velocity of, say 5 miles per second, it will blow it to smithereens," Levit said.
In the new study, the researchers suggest focusing a mid-powered laser through a telescope to shine on pieces of orbital debris that look like they're on a collision course. Each photon of laser light carries a tiny amount of momentum. Together, all the photons in the beam can nudge an object in space and slow it down by about .04 inches per second.
Shining the laser on bits of space litter for an hour or two a day should be enough to move the whole object by about 650 feet per day, the researchers show. That might not be enough to pull the object out of orbit altogether, but preliminary simulations suggest it could be enough to avoid more than half of all debris collisions.
NASA scientists have suggested shooting space junk with lasers before. But earlier plans relied on military-class lasers that would either destroy an object altogether, or vaporize part of its surface and create little plasma plumes that would rocket the piece of litter away. Those lasers would be prohibitively expensive, the team says, not to mention make other space-faring nations nervous about what exactly that military-grade laser is pointing at.
The laser to be used in the new system is the kind used for welding and cutting in car factories and other industrial processes. They're commercially available for about $0.8 million. The rest of the system could cost between a few and a few tens of millions of dollars, depending on whether the researchers build it from scratch or modify an existing telescope, perhaps a telescope at the Air Force Maui Optical Station in Hawaii or at Mt. Stromlo in Australia.
"This system solves technological problems, makes them cheaper, and makes it less of a threat that these will be used for nefarious things," said space security expert Brian Weeden, a technical adviser for the Secure World Foundation who was not involved in the new study. "It's certainly very interesting."
However, "I don't think this is a long-term solution," Weeden said. "It might be useful to buy some time. But I don't think it would replace the need to remove debris, or stop creating new junk."
Don Kessler, from whom the Kessler syndrome takes its name, agrees, and points out that laser light isn't forceful enough to divert the biggest pieces of junk.
"The only complete solution to is to prevent collisions involving the most massive objects in Earth orbit," he said.
Posted: 15 Mar 2011 08:58 AM PDT
The famed albatrosses of Midway Atoll took a beating from the tsunami, but their population will survive, say biologists on the islands.
There are, of course, more pressing concerns in the tsunami's aftermath than wildlife, and some might balk at paying attention to birds right now. But compassion isn't a zero-sum game, and Midway Atoll is one of Earth's natural treasures: 2.4 square miles of coral ringing a deep-sea mountaintop halfway between Honolulu and Tokyo, a flyspeck of dry land that's home to several million seabirds.
Roughly two-thirds of all Laysan albatrosses live on Midway's two islands, as do one-third of all black-footed albatrosses, and about 60 people. Many of them work at the Midway Atoll National Wildlife Refuge. They had time to prepare for the tsunami, which struck late on the night of March 10. Nobody was hurt; after the waves receded, they checked on the wildlife.
An estimated 1,000 Laysan adults were killed, and tens of thousands of chicks, said Refuge official Barry Stieglitz. Those figures represent just the first wave of mortality, as adults who were at sea when the tsunami hit may be unable to find their young on returning. Chicks now wandering on shore may be doomed — but in the long run, the population as a whole will recover.
"The loss of all these chicks is horrible. It's going to represent a significant portion of this year's Laysan albatross hatch. But in terms of overall population health, the most important animals are the proven, breeding adults," said Stieglitz. "In the long term, the greatest impact would be if we lost more adults. The population should come through this just fine."
On a sadder note, however, one of the wandering chicks is the first short-tailed albatross to hatch on Midway in decades. The species was hunted to near-extinction in the 19th century, its feathers so fashionable that a population of millions was reduced to a handful of juveniles who stayed at sea during the carnage. (Young short-tailed albatrosses live in the open ocean for several years before mating.) About 3,000 of the species now survive, and a few have recently made a home on Midway.
"If the chick lost one parent, it could be in danger. If it lost both, it's definitely out of luck," Stieglitz said.
Another well-known avian denizen of Midway is Wisdom, a 60-year-old female Laysan albatross. Banded for identification in 1956, Wisdom is the oldest known wild bird. In February, she was spotted rearing a new chick.
"When I gaze at Wisdom, I feel as though I've entered a time machine," wrote U.S. Fish and Wildlife Service biologist John Klavitter in an email. "My mind races to the past and all the history she has observed through time."
Midway's Laysan albatrosses feed in waters off Alaska, flying about 50,000 miles each year as adults. Wisdom has flown between 2 and 3 million miles in her lifetime, compensating for age with smarts and efficiency. She hasn't been spotted since the tsunami, but Stieglitz said the biologists haven't looked for her yet. Wisdom's nest is on high ground. They're not too worried about her.
Images: 1) Short-tailed albatross chick./Pete Leary, USFWS. 2) Wisdom, the 60-year-old Laysan albatross./John Klavitter, USFWS.
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