Scientists use brain waves to stroll through virtual world

Scientists use brain waves to stroll through virtual world

Japanese researchers say they have found a way to let people stroll through the virtual world of Second Life using their own imagination, in a development that could help paralysis patients.

Previous studies have shown people can move computer cursors through brain waves, but the Japanese team says it is the first to apply the technology to an Internet virtual world.

The technology "would enable people suffering paralysis to communicate with others or do business through chatting and shopping in a virtual world," said Junichi Ushiba, associate professor at Keio Univesity's rehabilitation centre.

Second Life is an increasingly popular virtual world in which people -- and animals -- are represented by animated avatars and can do everything from social activities to shopping.

Ushiba said Second Life could motivate patients with severe paralysis, who are often too depressed to undergo rehabilitation.

"If they can see with their own eyes their characters moving around, it could reinvigorate their brain activity and restore some functions," he said.

Under the technology, a person wearing head gear embedded with electrodes, which analyse brain waves in the cerebral motor cortex, would be able to move a Second Life character forward by thinking he or she is walking.

Imagining movement with the right or left hand would make the character turn accordingly in the same direction.

Researchers have previously put similar technology to work to scan brain waves to control objects such as computer cursors and electrical gears.

In the Keio University laboratory, the team has designed artificial arms that operate by reading brain waves, although none is known to be commercially available yet.

Ushiba said the technology could help people undergoing neuro-rehabilitation by stimulating brain activity.

Traditionally, "if a stroke leaves a man's right hand paralysed, he has been encouraged to use his left hand instead," Ushiba said.

"More recently, however, it has come to light that the paralysed hand would start moving better if you try to use it," Ushiba said, noting that attempts to use a numb hand increase brain activity.

The team next plans to test the technology on actual paralysis patients to see how they respond to the virtual world.

Mutating vaccine causes polio outbreak in Nigeria

Mutating vaccine causes polio outbreak in Nigeria

Nigeria is fighting an unusual outbreak of polio caused by a mutating polio vaccine, world health authorities say, but the only remedy is to keep vaccinating children there.

Officials of the World Health Organization fear that news of the outbreak, which began last year, will be a new setback for eradication efforts in northern Nigeria. Vaccinations were halted there in 2003 for nearly a year because of rumors that they sterilized Muslim girls or contained the virus that causes AIDS. During that lull, polio spread to many countries, although most have eliminated the small outbreaks that resulted.

Officials have denied suggestions that they kept the outbreak a secret, and said that they had not realized until recently that as many as 70 of Nigeria's last 1,300 polio cases stemmed from a mutant vaccine virus rather than from a "wild type" virus, which causes most polio.

"It was an oversight on our part," Dr. Bruce Aylward, director of the polio eradication campaign for the WHO, said Wednesday.

The agency discussed the first 16 cases it knew of at meetings early this year and posted information on its Web site in April, "but only in places where lab people would look," he said.

Outbreaks of vaccine-derived polio are unusual but not unheard of.

Individual cases have been known for years. For example, a former lieutenant governor of Virginia was partly paralyzed in 1973, apparently after changing the diapers of his son, who had received an oral vaccine.

The first spreading outbreak of a vaccine-derived strain, in which 22 children were paralyzed, was detected in 2001 in the Dominican Republic and Haiti.

Experts now believe that another took place in Egypt in the late 1980s but went unnoticed amid the much larger numbers of wild-type infections.

There have been others in the Philippines, Madagascar, China and Indonesia.

All were eventually eliminated by immunizing more children. Experts said that the most recent outbreak was able to spread because, until recently, only 30 percent to 40 percent of the children in northern Nigeria were vaccinated. About 70 percent are vaccinated there now, Aylward said.

In 2000, the United States switched to injected vaccine made from killed virus, which cannot mutate. But oral drops with the live, weakened version of the virus are still used in most poor countries, including those where the disease has never been eliminated: Nigeria, India, Pakistan and Afghanistan.

This vaccine, invented by Albert Sabin, is easier to give, offers much stronger protection and can beneficially "infect" other family members or neighbors, protecting them too.

But in rare cases, it can mutate into something resembling wild polio virus, which can paralyze or kill. Aylward pointed out that 10 billion doses of oral vaccine had been given in the past 10 years, so such mutations are presumably extremely unusual.

Polio often circulates undetected. In only one of 200 infections will it cause paralysis, which signals health officials to look for the virus in the area.

CT scans of the heart may come with trade-offs

CT scans of the heart may come with trade-offs

When my LDL, or "bad," cholesterol rose alarmingly (and for no apparent reason), I tried changing my diet. When that didn't work, the obvious answer was the cholesterol-lowering drugs called statins. But first, several people urged me to have a CT scan of my coronary arteries.

After all, they said, a scan takes only 10 minutes, it is noninvasive and it delivers no more radiation than a chest X-ray. If it showed that my arteries were clean, there would be no reason to take a drug; if it showed they were clogged, I'd have reason enough to take a statin.

Their suggestion prompted me first to take a hard look at what these scans are all about: whether they are safe, whether they really help people avoid heart attacks and whether a positive finding on a scan prompts people to make lifestyle changes to protect their hearts.

Coronary CT scans are being sold directly to the public, and they have found a market in health-conscious people who can afford them. But screening exams can have downsides. They can cause needless worry, and they sometimes reveal other potential conditions that require invasive procedures like biopsies to diagnose.

The older a person is, the higher the incidence of such incidental findings, studies have shown. In one study, they turned up in 40 percent of older people undergoing coronary CT scans. About a third of the findings were considered clinically significant. And there are as yet no data showing that these incidental findings are saving lives.

I soon learned that among the strongest proponents of CT scans of coronary arteries were physicians with financial ties to drug companies that make statins and others connected to imaging centers that would profit directly from widespread CT screenings. What, I wanted to know, do researchers with no such interests have to say about these scans?

What the Scans Show

CT scans of coronary arteries are most often used to screen seemingly healthy people for indirect evidence of atherosclerosis that may someday result in a heart attack or sudden cardiac death. The most frequently used test, electron beam tomography, typically costs $300 to $400 and is rarely covered by insurance. It can reveal calcium deposits that, experts say, reflect the extent of atherosclerosis in the arteries.

Most heart attacks result not from hard calcified plaque in the arteries, but from a chunk of soft plaque that breaks loose and blocks blood flow to the heart. Still, autopsy studies suggest there is a strong correlation between the amount of calcium and soft plaque in coronary arteries.

To visualize soft plaque directly, a procedure called CT angiography is done. It requires injecting a dye, and the scan that follows involves 3 to 10 times the radiation of electron beam tomography to detect calcification.

Last year the American Heart Association published in its journal Circulation a 30-page scientific assessment of the status of cardiac CT scanning.

The 12-member expert panel concluded that "it may be reasonable" to measure atherosclerosis using a CT scan in selected individuals who, based on known risk factors for heart disease, are at "intermediate risk" of a heart attack or sudden cardiac death within the next 10 years.

For someone whose risk factors are low, the experts reasoned, there is little to gain from a CT scan. Their chances of suffering a heart attack in the next decade are less than 10 percent. And for someone known to be at high risk, with more than 20 percent chance of a heart attack within 10 years, the results of a scan would not change the course of medical treatment. They must be treated aggressively, scan or no scan.

But for those in the middle, with a 10-year heart attack risk of 10 to 20 percent, learning that their arteries are clogged could change the course of medical treatment and perhaps foster changes in their habits. The factors considered in estimating risk are gender, age, cholesterol levels, smoking status and systolic blood pressure (the larger number) with and without treatment.

Each factor is assigned a point score. A 50-year-old man (6 points) who smokes (3 points) and has a total cholesterol of 200 to 239 milligrams per deciliter (3 points), an HDL level less than 40 (2 points) and a systolic blood pressure under 120 (no points) would rack up 14 points, giving him a 16 percent chance of a major cardiac event before he turns 60. (A woman at a comparable level of risk would have a point score of 21 or 22.) Based on currently available evidence, this man would be considered a good candidate for a CT scan.

Lowering the Risk

But lowering his risk should entail more than medication to improve his cholesterol readings. He should also quit smoking, change his diet and start exercising to help raise his HDL, the "good" cholesterol that protects the heart. Without intensive intervention to foster such lifestyle changes, according to a well-designed study by Dr. Patrick G. O'Malley and colleagues at Walter Reed Army Medical Center, there was no change in risk level a year after CT screening. And even intensive intervention had minimal effect.

Since even a heart attack does not always stop people from smoking or overindulging, some experts say artery scans are likely to benefit only the most highly motivated.

Nathan Wong, an epidemiologist at the University of California, Irvine, who had previously observed beneficial changes in risk following CT scans, is now conducting a more scientifically designed study of how people respond to the findings of a scan.

In an interview, Wong explained that while the results of a CT coronary artery scan did predict a person's chances of a major cardiac event in the next 10 years, it was not yet known whether the value of screening exceeded that of other tests for heart disease. No randomized trials to assess the benefits of CT coronary scanning have been conducted. Such trials are the only way to know for sure.

Dr. Michael Lauer of the National Heart, Lung and Blood Institute noted in the September issue of The Cleveland Clinic Journal of Medicine that screening individuals for evidence of arterial disease would have far less of an effect on the incidence of heart disease — the nation's leading killer — than a population-based approach to reduce cardiac risk factors.

As for me, a rough calculation of my risk factors showed that I was not at "intermediate risk" for heart disease, and therefore not a good candidate for a CT scan. So I decided to go the statin route, encouraged by recent evidence that statins, or their effect on cholesterol, protect not only against heart disease but may also help prevent dementia. I'll have another cholesterol test in a month or so.

Fact or Fiction?: Chewing Gum Takes Seven Years to Digest

Fact or Fiction?: Chewing Gum Takes Seven Years to Digest

A myth as durable as gum itself holds that the chewy confection sticks to your innards like it does to the bottom of a desk   

	Image: ©ISTOCKPHOTO.COM/KAMEEL
	STICKY SITUATION?:  Gum does not take seven years to digest but it's still not wise to swallow it.

It's a moment nearly everyone has experienced. You're contentedly chewing a wad of gum when an unforeseen turn brings about a quick disposal—the hard way. Whether the cause is imminent detection by a high school teacher, a dearth of garbage cans or even an untimely hiccup, you gulp down the rubbery gob whole. It's only then that a refrain from childhood echoes through your mind: "Don't swallow chewing gum—it will stay in your system for seven years!" As the minty mass descends into your digestive abyss, you wonder: "Will I really be part Wrigley for years to come?"

Rest assured—this decades-old bit of folklore, of unknown origin but almost universal renown, has little basis in fact. Asked if the rumor is medically unfounded, pediatric gastroenterologist David Milov of the Nemours Children's Clinic in Orlando, Fla., replies: "I can tell you that with complete certainty."

If the legend were true, Milov says, "that would mean that every single person who ever swallowed gum within the last seven years would have evidence of the gum in the digestive tract," but colonoscopies and capsule endoscopy procedures turn up no such evidence. "On occasion we'll see a piece of swallowed gum," he says, "but usually it's not something that's any more than a week old."

According to Rodger Liddle, a gastroenterologist at the Duke University School of Medicine, "nothing would reside that long, unless it was so large it couldn't get out of the stomach or it was trapped in the intestine." To put that size into perspective, Liddle says that swallowed quarters usually pass, but that larger coins or objects might not.

So what does become of gum that's been chewed up but not spit out? Not much, as it happens. Some of the components, such as sweeteners, are broken down, but the gum's base is largely indigestible. The Food and Drug Administration defines chewing gum base as a "nonnutritive masticatory substance" that may be composed of any number of natural or synthetic elastomers, or rubberlike materials, as well as plasticizing softeners, resins and preservative antioxidizing agents. The permitted elastomers include natural, tree-derived chicle, a gum chewed by indigenous Central Americans, and the somewhat less traditional butyl rubber, which also finds use in the manufacture of inner tubes.

Chewing gum, of course, has been around in one form or another for thousands of years: tooth-marked lumps of birch bark tar have been found in Europe that date back to the Mesolithic period of the Stone Age. And this past summer, researchers reported that quids—balls of plant material chewed by ancient Native Americans—had yielded DNA from members of a tribe called the Western Basketmakers, who lived in the southwestern U.S. some 2,000 years ago.

Unsurprisingly, perhaps, the human body cannot do much with these rubbery concoctions, resilient. Chewing gum "is pretty immune to the digestive process," Milov says. "It probably passes through slower than most foodstuffs, but eventually the normal housekeeping waves in the digestive tract will sort of push it through, and it will come out pretty unmolested."

Nevertheless, the usually safe passage of gum through the system doesn't mean it is wise to habitually swallow it. As Milov and his colleagues wrote in Pediatrics in 1998, chronic gum swallowing—or swallowing gum in conjunction with other indigestibles—can spell trouble. The team's report describes three children suffering from gum-based gastrointestinal blockages, two of whom received gum as positive reinforcement for good behavior and regularly disposed of the treat by swallowing it. In both cases the children became constipated, as the gum snowballed into a substantial "taffylike" mass that required extraction. In the third patient, a girl just a year and a half old, four coins were found lodged in the esophagus, fused into a single blob by a wad of chewing gum.

"I've had another case that was really interesting," Milov adds, "and that was somebody who swallowed sunflower seeds—[and] also, the shells." Upon examining the patient's lower digestive tract, Milov found "all these very prickly seeds that were congealed around gum," forming a body that he describes as "like a porcupine."

Whereas the real (if remote) prospect of an internal quilling ought to be enough to discourage anyone from regularly swallowing gum, the mythical seven-year deterrent persists. Because it causes no real harm, and in fact probably serves to prevent many cases like those Milov describes, the urban legend seems likely to stick around for the foreseeable future. Unlike, thankfully, that wad of spearmint gum you swallowed in high school.

Gigantic Empty Space in Universe Discovered

Gigantic Empty Space in Universe Discovered

It’s understandable when astronomers get excited about discovering, say, an extrasolar planet. But it’s also a big deal when they find nothing — that is, a mind-bogglingly huge expanse of space, some 1 billion light-years across, that contains no galaxies or black holes or even that ominous-sounding dark matter.

"Not only has no one ever found a void this big, but we never even expected to find one this size," explains University of Minnesota astronomy professor Lawrence Rudnick, who along with colleagues Shea Brown and Liliya R. Williams reported the discovery in a scientific paper accepted for publication in the Astrophysical Journal.

The astronomers discovered the empty region while examining data from a sky survey carried out by the Very Large Array radio telescope, part of the National Radio Astronomy Laboratory.

"One morning I was a little bored, and said, 'Why don’t I look in the direction of the WMAP [Wilkinson Microwave Anisotropy Probe] cold spot?’" Rudnick recounted for New Scientist.

The cold spot was a mysterious area that stood out in a map of cosmic microwave background radiation made by a NASA satellite in 2001. CMB remains from the "Big Bang" that created the cosmos, and the astronomers wondered if the irregularity in the CMB map might reveal some structure from the universe’s infancy. (Another possibility was that the radio waves were being blocked by a celestial object closer to Earth.)

Instead, the astronomers found, the slightly colder temperature of the CMB in the region was caused by a massive expanse of emptiness located some 6 to 10 billion light-years from Earth.

Though other empty spaces in the universe have been discovered, this one is about 1,000 times larger than what astronomers would have expected.

"In our own Milky Way Galaxy, we have 100 billion stars," Rudnick explained to the Minneapolis Star-Tribune. "If we were to go off in a spaceship … traveling at the speed of light, you would only have to go a few years before you find another star … what we found is a place where you'd travel for a billion years before you found another concentration of mass. It would be a very boring journey of a billion years."

The discovery could shed light on how the universe took shape. "It is … part of the story of how we got here," Rudnick told the Star-Tribune.

From NRAO, here’s a graphic that depicts the cold spot. From the Google Earth Community discussion board, here are directions on how you can view the location in the sky.