Archive for the ‘University of Rochester’ Category


Doctoral student Joseph Choi demonstrates a multidirectional ‘perfect paraxial’ cloak using 4 lenses.


Choi uses his hand to further demonstrate his device.


A laser shows the paths that light rays travel through the system, showing regions that can be used for cloaking an object.

Scientists at the University of Rochester have discovered a way to hide large objects from sight using inexpensive and readily available lenses.

Cloaking is the process by which an object becomes hidden from view, while everything else around the cloaked object appears undisturbed.

“A lot of people have worked on a lot of different aspects of optical cloaking for years,” John Howell, a professor of physics at the upstate New York school, said on Friday.

The so-called Rochester Cloak is not really a tangible cloak at all. Rather the device looks like equipment used by an optometrist. When an object is placed behind the layered lenses it seems to disappear.

Previous cloaking methods have been complicated, expensive, and not able to hide objects in three dimensions when viewed at varying angles, they say.

“From what, we know this is the first cloaking device that provides three-dimensional, continuously multidirectional cloaking,” said Joseph Choi, a graduate student who helped develop the method at Rochester, which is renowned for its optical research.

In their tests, the researchers have cloaked a hand, a face, and a ruler – making each object appear “invisible” while the image behind the hidden object remains in view. The implications for the discovery are endless, they say.

“I imagine this could be used to cloak a trailer on the back of a semi-truck so the driver can see directly behind him,” Choi said. “It can be used for surgery, in the military, in interior design, art.”

Howell said the Rochester Cloak, like the fictitious cloak described in the pages of the Harry Potter series, causes no distortion of the background object.

Building the device does not break the bank either. It cost Howell and Choi a little over $US1000 ($1140) in materials to create it and they believe it can be done even cheaper.

Although a patent is pending, they have released simple instructions on how to create a Rochester Cloak at home for under $US100 (114).

There is also a one-minute video about the project on YouTube.

http://www.smh.com.au/technology/sci-tech/scientists-unveil-invisibility-cloak-to-rival-harry-potters-20140927-10n1dp.html

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sleepingbrain_wide-e40290d47221863e13990f78f86b983781d5673e-s40-c85

While the brain sleeps, it clears out harmful toxins, a process that may reduce the risk of Alzheimer’s, researchers say.

During sleep, the flow of cerebrospinal fluid in the brain increases dramatically, washing away harmful waste proteins that build up between brain cells during waking hours, a study of mice found.

“It’s like a dishwasher,” says Dr. Maiken Nedergaard, a professor of neurosurgery at the University of Rochester and an author of the study in Science.

The results appear to offer the best explanation yet of why animals and people need sleep. If this proves to be true in humans as well, it could help explain a mysterious association between sleep disorders and brain diseases, including Alzheimer’s.

Nedergaard and a team of scientists discovered the cleaning process while studying the brains of sleeping mice. The scientists noticed that during sleep, the system that circulates cerebrospinal fluid through the brain and nervous system was “pumping fluid into the brain and removing fluid from the brain in a very rapid pace,” Nedergaard says.

The team discovered that this increased flow was possible in part because when mice went to sleep, their brain cells actually shrank, making it easier for fluid to circulate. When an animal woke up, the brain cells enlarged again and the flow between cells slowed to a trickle. “It’s almost like opening and closing a faucet,” Nedergaard says. “It’s that dramatic.”

Nedergaard’s team, which is funded by the National Institute of Neurological Disorders and Stroke, had previously shown that this fluid was carrying away waste products that build up in the spaces between brain cells.

The process is important because what’s getting washed away during sleep are waste proteins that are toxic to brain cells, Nedergaard says. This could explain why we don’t think clearly after a sleepless night and why a prolonged lack of sleep can actually kill an animal or a person, she says.

So why doesn’t the brain do this sort of housekeeping all the time? Nedergaard thinks it’s because cleaning takes a lot of energy. “It’s probably not possible for the brain to both clean itself and at the same time [be] aware of the surroundings and talk and move and so on,” she says.

The brain-cleaning process has been observed in rats and baboons, but not yet in humans, Nedergaard says. Even so, it could offer a new way of understanding human brain diseases including Alzheimer’s. That’s because one of the waste products removed from the brain during sleep is beta amyloid, the substance that forms sticky plaques associated with the disease.

That’s probably not a coincidence, Nedergaard says. “Isn’t it interesting that Alzheimer’s and all other diseases associated with dementia, they are linked to sleep disorders,” she says.

Researchers who study Alzheimer’s say Nedergaard’s research could help explain a number of recent findings related to sleep. One of these involves how sleep affects levels of beta amyloid, says Randall Bateman, a professor of neurology Washington University in St. Louis who wasn’t involved in the study.

“Beta amyloid concentrations continue to increase while a person is awake,” Bateman says. “And then after people go to sleep that concentration of beta amyloid decreases. This report provides a beautiful mechanism by which this may be happening.”

The report also offers a tantalizing hint of a new approach to Alzheimer’s prevention, Bateman says. “It does raise the possibility that one might be able to actually control sleep in a way to improve the clearance of beta amyloid and help prevent amyloidosis that we think can lead to Alzheimer’s disease.”

http://www.npr.org/blogs/health/2013/10/17/236211811/brains-sweep-themselves-clean-of-toxins-during-sleep

http://m.sciencemag.org/content/342/6156/373.abstract

Thanks to Kebmodee for bringing this to the It’s Interesting community.

SolarProminence_0

If you put a steamy cup of coffee in the refrigerator, it wouldn’t immediately turn cold. Likewise, if the sun simply “turned off” (which is actually physically impossible), the Earth would stay warm—at least compared with the space surrounding it—for a few million years. But we surface dwellers would feel the chill much sooner than that.

Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet’s core would equal the heat that the Earth radiates into space, explains David Stevenson, a professor of planetary science at the California Institute of Technology.

Although some microorganisms living in the Earth’s crust would survive, the majority of life would enjoy only a brief post-sun existence. Photosynthesis would halt immediately, and most plants would die in a few weeks. Large trees, however, could survive for several decades, thanks to slow metabolism and substantial sugar stores. With the food chain’s bottom tier knocked out, most animals would die off quickly, but scavengers picking over the dead remains could last until the cold killed them.

Humans could live in submarines in the deepest and warmest parts of the ocean, but a more attractive option might be nuclear- or geothermal-powered habitats. One good place to camp out: Iceland. The island nation already heats 87 percent of its homes using geothermal energy, and, says astronomy professor Eric Blackman of the University of Rochester, people could continue harnessing volcanic heat for hundreds of years.

Of course, the sun doesn’t merely heat the Earth; it also keeps the planet in orbit. If its mass suddenly disappeared (this is equally impossible, by the way), the planet would fly off, like a ball swung on a string and suddenly let go.

http://www.popsci.com/science/article/2013-07/if-sun-went-out-how-long-could-life-earth-survive?cmpid=obinsite

suicide

The suicide rate among middle-aged Americans climbed a startling 28 percent in a decade, a period that included the recession and the mortgage crisis, the government reported Thursday. The trend was most pronounced among white men and women in that age group. Their suicide rate jumped 40 percent between 1999 and 2010. But the rates in younger and older people held steady. And there was little change among middle-aged blacks, Hispanics and most other racial and ethnic groups, the report from the Centers for Disease Control and Prevention found.

Why did so many middle-aged whites — that is, those who are 35 to 64 years old — take their own lives?

One theory suggests the recession caused more emotional trauma in whites, who tend not to have the same kind of church support and extended families that blacks and Hispanics do.

The economy was in recession from the end of 2007 until mid-2009. Even well afterward, polls showed most Americans remained worried about weak hiring, a depressed housing market and other problems.

Pat Smith, violence-prevention program coordinator for the Michigan Department of Community Health, said the recession — which hit manufacturing-heavy states particularly hard — may have pushed already-troubled people over the brink. Being unable to find a job or settling for one with lower pay or prestige could add “that final weight to a whole chain of events,” she said.

Another theory notes that white baby boomers have always had higher rates of depression and suicide, and that has held true as they’ve hit middle age. During the 11-year period studied, suicide went from the eighth leading cause of death among middle-aged Americans to the fourth, behind cancer, heart disease and accidents.

“Some of us think we’re facing an upsurge as this generation moves into later life,” said Dr. Eric Caine, a suicide researcher at the University of Rochester.

One more possible contributor is the growing sale and abuse of prescription painkillers over the past decade. Some people commit suicide by overdose. In other cases, abuse of the drugs helps put people in a frame of mind to attempt suicide by other means, said Thomas Simon, one of the authors of the CDC report, which was based on death certificates.

People ages 35 to 64 account for about 57 percent of suicides in the U.S.

The report contained surprising information about how middle-aged people kill themselves: During the period studied, hangings overtook drug overdoses in that age group, becoming the No. 2 manner of suicide. But guns remained far in the lead and were the instrument of death in nearly half of all suicides among the middle-aged in 2010.

The CDC does not collect gun ownership statistics and did not look at the relationship between suicide rates and the prevalence of firearms.

For the entire U.S. population, there were 38,350 suicides in 2010, making it the nation’s 10th leading cause of death, the CDC said. The overall national suicide rate climbed from 12 suicides per 100,000 people in 1999 to 14 per 100,000 in 2010. That was a 15 percent increase.

For the middle-aged, the rate jumped from about 14 per 100,000 to nearly 18 — a 28 percent increase. Among whites in that age group, it spiked from about 16 to 22.

Suicide prevention efforts have tended to concentrate on teenagers and the elderly, but research over the past several years has begun to focus on the middle-aged. The new CDC report is being called the first to show how the trend is playing out nationally and to look in depth at the racial and geographic breakdown.

Thirty-nine out of 50 states registered a statistically significant increase in suicide rates among the middle-aged. The West and the South had the highest rates. It’s not clear why, but one factor may be cultural differences in willingness to seek help during tough times, Simon said.

Also, it may be more difficult to find counseling and mental health services in certain places, he added.

Suicides among middle-aged Native Americans and Alaska Natives climbed 65 percent, to 18.5 per 100,000. However, the overall numbers remain very small — 171 such deaths in 2010. And changes in small numbers can look unusually dramatic.

The CDC did not break out suicides of current and former military service members, a tragedy that has been getting increased attention. But a recent Department of Veterans Affairs report concluded that suicides among veterans have been relatively stable in the past decade and that veterans have been a shrinking percentage of suicides nationally.

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

http://bigstory.ap.org/article/us-suicide-rate-rose-sharply-among-middle-aged