- Nearsightedness Increasing in U.S.
- DIY Home Sleep Research with Cameras, Accelerometers, EEGs
- Video: Black Carbon Travels the Globe
- Tool Use Found in Octopuses
- Hacked Wiimote Makes Super Scientific Sensor
- Bacterial Micro Machines Turn Tiny Gears
Posted: 15 Dec 2009 08:35 AM PST
It looks like nearsightedness is on the rise in the United States.
Researchers tapped into a wide-ranging health survey to rate vision in the population in the early 1970s and roughly 30 years later. They compared eyesight information for more than 4,400 people tested in 1971 and 1972 with data from another set of 8,300 people tested from 1999 to 2004.
This broad survey showed that 25 percent of those examined in the early 1970s were deemed to be nearsighted, compared with 42 percent examined three decades later, the researchers report in the December Archives of Ophthalmology. That's an increase of 66 percent.
Myopia severity also increased, with moderate nearsightedness doubling between the two time periods and severe cases, although uncommon, also rising sharply. Mild myopia cases increased slightly, from about 13 percent to 18 percent. This group included some people who did not need corrective lenses, says study coauthor Susan Vitale, an epidemiologist at the National Eye Institute in Bethesda, Maryland.
Among blacks, the overall myopia rate was lower than in whites but still jumped from 13 to 34 percent over the three-decade span.
When analyzing the more recent eye-exam data, the scientists used only diagnoses that were made with the same technology used in the 1970s — mainly standard eye tests and trial lenses. Including diagnoses made with more advanced technology that has become available only recently might have biased the comparison, Vitale says.
The cause of nearsightedness is poorly understood. Past research has linked added risk to both a genetic predisposition to nearsightedness and to excessive amounts of near work, the kind of tasks that require peering at written words or small objects.
"Some people would say near work is a reasonable explanation," Vitale says, particularly with the advent of video games and other electronic devices. Children also spend less time outdoors than they once did, she says. And some researchers contend that more outdoor time means seeing in better light, focusing farther.
As for hereditary factors, research shows some added risk for children born to nearsighted parents. "It might be that somehow the population has changed and that there are more people floating around that have more genetic risk," Vitale says.
Posted: 15 Dec 2009 03:00 AM PST
If you sleep like a princess, and wonder what keeps you tossing and turning at night, perhaps there's a gadget that can find the pea under your mattress.
Companies are begun selling electronics directly to consumers that can help anyone monitor their sleep and adjust their bedtime routine, and some people haveinvented their own tracking systems. Slip on a wireless wristband orheadband and focus your camcorderbefore you hit the sack, and the next morning you will wake up to a mound of data.
At a Quantified Self meetup at Wired's San Francisco offices Dec. 7, around 100 people gathered to share their data-driven sleep habits. The founders of the Wakemate startup were on hand to talk about their wristband that keeps track of your sleep patterns. It's equipped with an accelerometer and a bluetooth transmitter that connects with a free smartphone app. The accelerometer is the same that's in the highly popular (and backordered) Fitbit exercisetracking device.The Wakemate will be very hackable and cost just $50,but won't ship until January.
So if it's a Christmas gift for a sleepy friend you're after, you might want to check out theZeo Personal Sleep Coach, an alarm clock that records electrical signals from your brain with a headband. In the morningit returnsa chart of how much time you spent in light, deep and REM sleep, as well as a personal sleep score (which they call your ZQ). It can alsomake waking up easierto wake you if you ask it to, by choosing a lighter sleep moment torouse you.
Techology investor Esther Dyson gave the Zeo a mixed review at the meetup. For example, the headband has little pads that wear out quickly, and must be replaced. But the biggest problems are on the software side: Zeo does not allow more than one user to share the device, and makes it hard to extract the raw data. Despite those flaws, Dyson said she plans on experimenting with it some more.
If you want an even better picture of your sleep, you can follow the example of San Francisco resident, Matt Bell. After years of feeling drowsy all day and not knowing whay, he set up a bedside camcorder with an infrared illuminator in search of an answer. The footagewas revealing.
"The biggest thing that surprised me was seeing how much I moved around while sleeping," Bell said at the meetup. "It was fascinating to glimpse at the workings of this hidden unconscious world that occupies close to a third of our lives."
In his quest for a perfect night of rest, Bell experimented with the lighting in his bedroom, his diet, his sleeping positions, and lots of drugs. He even kept a daily log of how well he slept, his mood during the following day, and how much excitement he experienced during the prior day.
Photos: Wakemate, Zeo
Video: Matt Bell/YouTube
Posted: 14 Dec 2009 04:56 PM PST
SAN FRANCISCO — Black carbon — the soot emitted when fuels like diesel, wood and coal are burned — may have a bigger impact on climate in some areas than greenhouse gases. New research presented here at the American Geophysical Union meeting shows that the 20 percent decrease in the extent of Himalayan glaciers since the 1960's may be partly due to an influx of black carbon from Asian cities.
Using satellite data and computer models, NASA atmospheric scientist William Lau and colleagues put together this animation of Earth's atmospheric concentration of black carbon from August to November. The time of fastest glacial melting on the western Tibetan Plateau coincides with the highest concentration of black carbon in the area, Lau reported.
"Over areas of the Himalayas, the rate of warming is more than five times faster than warming globally," Lau said in a press release. "Based on the differences it's not difficult to conclude that greenhouse gases are not the sole agents of change in this region. There's a localized phenomenon at play."
The dark soot particles affect the area by absorbing sunlight and heating the air around them. When black carbon gets trapped in the air flanking the Himalayas, it creates a warm layer that then rises into the mountains and accelerates glacial melting. The effect of this regional phenomenon may even be greater than that of global warming from greenhouse gases.
Video: NASA/Goddard Space Flight Center Scientific Visualization Studio
Posted: 14 Dec 2009 02:44 PM PST
After years of surprising scientists with their cleverness and smarts, some octopuses appear to also use tools.
Veined octopuses observed off the coast of Indonesia carried coconut shell halves under their bodies, and assembled them as necessary into shelters — something that wasn't supposed to be possible in their corner of the animal kingdom.
"To date, invertebrates have generally been regarded as lacking the cognitive abilities to engage in such sophisticated behaviors," wrote Museum Victoria biologists who described the octopuses in a paper published Monday in Current Biology. "The discovery of this octopus tiptoeing across the sea ﬂoor with its prized coconut shells suggests that even marine invertebrates engage in behaviors that we once thought the preserve of humans."
In captivity, some species of octopuses have solved mazes, remembered cues and passed other cognitive tests typically associated with advanced vertebrates. More anecdotally, they're known for popping aquarium hoods, raiding other tanks and demonstrating what might be called mischief.
All this has come as a bit of a surprise to scientists. After all, octopuses are descended from mollusks. They're more closely related to clams than to people. They're not supposed to be smart. But it's hard to argue with the evidence, and in recent years, researchers have grappled with the possibility that octopuses can even use tools.
That debate has focused on octopuses seen barricading their den openings with stones. In the end, that behavior wasn't accepted as genuine tool use, because it seemed more instinctive than calculated. (Another contested invertebrate behavior is the use of shells as homes by hermit crabs. According to the conventional wisdom, tools require direct manipulation, so the shells are no more tools than are human houses.)
Such definitions are inevitably ambiguous. But there's no ambiguity in the veined octopuses found flushing mud from buried coconut shells, stacking them for transport — an awkward process that required the octopuses to walk on tiptoe with the upturned shells clutched beneath them — and finally turning them into hard-shelled tents.
"The fact that the shell is carried for future use rather than as part of a speciﬁc task differentiates this behavior from other examples of object manipulation by octopuses," wrote the researchers.
With their tents, the veined octopus has joined chimpanzees, monkeys, dolphins and crows in the ever-expanding menagerie of non-human tool users. But as significant as the finding may be, the moment of discovery wasn't exactly solemn.
"I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away. It was an extremely comical sight," said Julia Finn, a Museum Victoria biologist, in a press release. "I have never laughed so hard underwater."
Image: At top left, a veined octopus; bottom left, a veined octopus carrying its shells; at right, inside the assembled shell house/Current Biology
Citation: "Defensive tool use in a coconut-carrying octopus." By Julian K. Finn, Tom Tregenza and Mark D. Norman. Current Biology, Vol. 19 No. 23, December 15, 2009.
Posted: 14 Dec 2009 02:04 PM PST
SAN FRANCISCO — To gamers, $40 may seem like a steep price to replace a Wii remote controller, but to scientists, a hacked Wiimote is a steal compared to the pricey sensors needed for a lot of field research.
Inspired by videos of renowned hacker Johnny Chung Lee turning the Wiimote into a finger-tracking device and a touchscreen white board, physicist Rolf Hut of of Delft University of Technology built a Wiimote wind sensor.
"It was just a bendy pole with an empty bottle on top with an LED light on the bottle," Hut said. "And it swayed in the wind."
The Wiimote can track just about anything: All that's needed is an LED light. Hydrologist William Luxemburg of Delft University of Technology in the Netherlands demonstrated a hacked water-level sensor made from a Wiimote and a plastic boat at the meeting of the American Geophysical Union here Monday.
"Just switch it on and make sure it doesn't get wet," Luxemburg said.
Luxemburg's team aimed the Wiimote at a problem that can be very tricky for hydrologists: measuring evaporation on a body of water. The easiest way to measure evaporation is to place pans of water near the lake, or whatever water is being studied, and put pressure sensors in them. The sensors record the drop in pressure as more and more water disappears. But this equipment can run $500 or more, and still the measurements aren't accurate because the water in the pan gets warmer on land than it would in the lake. Alternatively, measuring the level of water in a pan that is floating in a lake is also tricky because the pan will inevitably be moving.
The Wiimote could overcome the evaporation-measurement problems. It has a tri-axial accelerometer and a high-resolution, high-speed infrared camera, which can sense movement with better than 1 millimeter accuracy.
Luxemburg's team tested it in a floating evaporation pan, using a float with an LED. With a Wiimote aimed at the float, and some hacking and programming of the Wiimote's output, they were able to get highly accurate, real-time data on water level wirelessly sent to a laptop.
The IR camera can track up to four LED lights at once, so scientists can use several floats to calculate the water's plane. To be as accurate with pressure sensors, you'd need more and costlier units.
Luxemburg and Hut's goal was to show other scientists at the meeting that the videogame controller can be a legitimate piece of scientific equipment that they should consider deploying in all types of field experiments. They've gotten interest from colleagues who study building construction at Delft University because of the controller's accelerometer.
"If you have a structure that collapses and you have Wiimotes on the building, you could see how fast it falls," Luxemburg said.
And judging from the crowd at their demonstration, plenty of scientists are interested.
"I'm pretty sure within the next four to six weeks, some good ideas will come along," Hut said.
Of course, each experiment will have it's own challenges that require specific hacking of the Wiimote. It will need longer battery life and a way to store data so it can be left to work alone at a field site. But Hut is confident all that can be done, and more.
"I still want to do something to measure temperature with it," Hut said. "I just don't know how yet."
But the basics, he said, are easy. His original wind-sensor demo took him just a few hours to build and was a welcome break from the network and signal analysis he usually does.
"There are probably better ways to measure wind, but it was a day well-spent," Hut said. "I really felt the need to solder something."
Images: 1) Betsy Mason/Wired.com. 2) Hubert Savenijel/ Delft University of Technology. 3) Betsy Mason/Wired.com.
Posted: 14 Dec 2009 01:08 PM PST
The power of swimming bacteria can be harnessed to turn tiny gears, opening the possibility of building hybrid biological machines at the microscopic scale.
The gears, just 380 micrometers in diameter, are turned by the collective swimming motion of bacteria a million times lighter than the gears themselves, scientists announced in a paper Monday in the Proceedings of the National Academy of Sciences.
The rotational velocity of the objects can be controlled by altering the levels of air and nitrogen in the liquid solution. In a sense, the Argonne National Laboratory scientists have almost created living micro machines.
"Our discovery demonstrates how microscopic swimming agents, such as bacteria or man-made nanorobots, in combination with hard materials can constitute a 'smart material,' which can dynamically alter its microstructures, repair damage, or power microdevices," said Argonne National Laboratory physicist Igor Aronson in a press release.
An individual bacterium's motion appears random. However, at a concentration of about 10 billion bacterial cells per cubic centimeter, the organisms begin to swim together in what the researchers described as "self-organized, large-scale vortices." It's that collective motion that powers the gears' movement. In their experiments, the motion petered out if the concentration was increased to anything beyond 40 billion bacteria per cubic centimeter, as the organisms appear to shift their behavior toward creating biofilms.
While scientific understanding of collective bacterial behavior is still limited, the new paper provides a powerful demonstration that it may be possible to control them with some precision.
"The ability to harness and control the power of bacterial motions is an important requirement for further development of hybrid biomechanical systems driven by microorganisms," Aronson said.
By experimenting with the type of gear, the amount of bacteria and the oxygen levels in the solution, they were even able to power multiple gears. Even so, the total power the gear extracts from the motion of the bacteria is only on the order of a quadrillionth of a watt.
That's too small to power any real-world machine, but the scientists hope that such tiny motors could be useful for microfluidic devices or fluid mixers. At a more fundamental level, they also highlight the power of collective movements in bacteria.
Video: Igor Aronson
Citation: "Swimming bacteria power microscopic gears" by Andrey Sokolov, Mario M. Apodaca, Bartosz A. Grzybowski, and Igor S. Aranson. PNAS, December 15. PNAS, December 15.
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