Source: http://news.feedzilla.com/en_us/stories/politics/top-stories/297898327?client_source=feed&format=rss
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Wednesday, April 10, 2013
Advancing secure communications: A better single-photon emitter for quantum cryptography
Advancing secure communications: A better single-photon emitter for quantum cryptography
Wednesday, April 10, 2013In a development that could make the advanced form of secure communications known as quantum cryptography more practical, University of Michigan researchers have demonstrated a simpler, more efficient single-photon emitter that can be made using traditional semiconductor processing techniques.
Single-photon emitters release one particle of light, or photon, at a time, as opposed to devices like lasers that release a stream of them. Single-photon emitters are essential for quantum cryptography, which keeps secrets safe by taking advantage of the so-called observer effect: The very act of an eavesdropper listening in jumbles the message. This is because in the quantum realm, observing a system always changes it.
For quantum cryptography to work, it's necessary to encode the message?which could be a bank password or a piece of military intelligence, for example?just one photon at a time. That way, the sender and the recipient will know whether anyone has tampered with the message.
While the U-M researchers didn't make the first single-photon emitter, they say their new device improves upon the current technology and is much easier to make.
"This thing is very, very simple. It is all based on silicon," said Pallab Bhattacharya, the Charles M. Vest Distinguished University Professor of Electrical Engineering and Computer Science, and the James R. Mellor Professor of Engineering.
Bhattacharya, who leads this project, is a co-author of a paper on the work published in Nature Communications on April 9.
Bhattacharya's emitter is a single nanowire made of gallium nitride with a very small region of indium gallium nitride that behaves as a quantum dot. A quantum dot is a nanostructure that can generate a bit of information. In the binary code of conventional computers, a bit is a 0 or a 1. A quantum bit can be either or both at the same time.
The semiconducting materials the new emitter is made of are commonly used in LEDs and solar cells. The researchers grew the nanowires on a wafer of silicon. Because their technique is silicon-based, the infrastructure to manufacture the emitters on a larger scale already exists. Silicon is the basis of modern electronics.
"This is a big step in that it produces the pathway to realizing a practical electrically injected single-photon emitter," Bhattacharya said.
Key enablers of the new technology are size and compactness.
"By making the diameter of the nanowire very small and by altering the composition over a very small section of it, a quantum dot is realized," Bhattacharya said. "The quantum dot emits single-photons upon electrical excitation."
The U-M emitter is fueled by electricity, rather than light?another aspect that makes it more practical. And each photon it emits possesses the same degree of linear polarization. Polarization refers to the orientation of the electric field of a beam of light. Most other single-photon emitters release light particles with a random polarization.
"So half might have one polarization and the other half might have the other," Bhattacharya said. "So in cryptic message, if you want to code them, you would only be able to use 50 percent of the photons. With our device, you could use almost all of them."
This device operates at cold temperatures, but the researchers are working on one that operates closer to room temperature.
The paper is titled "Electrically-driven polarized single-photon emission from an InGaN quantum dot in a GaN nanowire." The first author is Saniya Deshpande, a graduate student in electrical engineering and computer science. The work is supported by the National Science Foundation. The device was fabricated at the U-M Lurie Nanofabrication Facility.
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University of Michigan: http://www.umich.edu/
Thanks to University of Michigan for this article.
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Facebook Apologized to a Mom After Accidentally Banning Her Twice for Posting Breastfeeding Pictures
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Tuesday, April 9, 2013
The Daily Roundup for 04.08.2013
You might say the day is never really done in consumer technology news. Your workday, however, hopefully draws to a close at some point. This is the Daily Roundup on Engadget, a quick peek back at the top headlines for the past 24 hours -- all handpicked by the editors here at the site. Click on through the break, and enjoy.
Source: http://www.engadget.com/2013/04/08/the-daily-roundup-for-04-08-2013/
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93% Zero Dark Thirty
All Critics (243) | Top Critics (45) | Fresh (228) | Rotten (17) | DVD (2)
What's striking is the absence of triumphalism -- Bigelow doesn't shy away from showing the victims shot down in cold blood in the compound -- and we come away with the overwhelming sense that this has been a grim, dark episode in our history.
This is an instant classic.
Chastain makes Maya as vivid as a bloodshot eye. Her porcelain skin, delicate features and feminine attire belie the steel within.
No doubt Zero Dark Thirty serves a function by airing America's dirty laundry about detainee and torture programs, but in its wake, there's a crying need for a compassionate Coming Home to counter its brutal Deer Hunter.
While "Zero Dark Thirty" may offer political and moral arguing points aplenty, as well as vicarious thrills,as a film it's simply too much of a passable thing.
From the very first scenes of Zero Dark Thirty, director Kathryn Bigelow demonstrates why she is such a formidable filmmaker, as adept with human emotion as with visceral, pulse-quickening action.
Kathryn Bigelow's Zero Dark Thirty is a grueling masterpiece that captures the hunt for bin Laden with a daunting amount of realism and efficiency.
Slathered in controversy, Kathryn Bigelow's Zero Dark Thirty confidently and forcefully storms onto DVD with an admirable A/V transfer, only hindered by a paltry gathering of extras from Sony.
The direction by Kathryn Bigelow, who won Oscars for Best Film and Best Director in her previous film "The Hurt Locker," is fierce and focused...
Despite what those silly Oscars would have you believe, it was this movie, not Argo, that was the finest of 2012.
Indulges Cheneyian fantasies complete with the bad-movie scene of the prisoner's defiance: "You're just a garbage man in the corporation," shouts the Arab who needs a lesson in manners from the Ph.D. (in torture?) who is racking him.
Bigelow tells the story very well, very efficiently, but doesn't really say much about it, which is ironic given the response to the film in some quarters.
Kathryn Bigelow takes the procedural model and brushes away every unnecessary detail, leaving behind a heavy, blunt object of a film that is also hugely watchable, engrossing and, best of all... highly suspenseful.
Rotten Tomatoes notes that I agree with Tomatometer critics 80 percent of the time, but this is one of those times I have to part ways with them.
Bigelow has directed excellent movies before, but this deserves to be remembered as the film that established her as a master.
You can't deny that what Zero Dark Thirty sets out to do, it does excellently.
An exhilarating and compelling historical document worthy of praise.
Bigelow's latest proves a rewarding piece of filmmaking, one that, in its best moments at least, is as gripping and as troubling as anything the director's ever made.
Bigelow and screenwriter Mark Boal shape history -- those breaks, big and small, that led to the killing of Osama bin Laden -- into one of the finest fact-based thrillers since "All the President's Men."
Purely as cinematic exercise, Zero Dark Thirty is an exhilarating piece of work. But, beyond its for-the-times subject matter, the work does not linger whatsoever.
Zero Dark Thirty is interesting as opposed to enjoyable, intriguing as opposed to entertaining, and certainly less memorable than The Hurt Locker.
It's quite remarkable how Bigelow and Boal managed to take 12 years of information (including a conclusion that everyone knows) and packaged it into a coherent, intimate and intense movie.
We know the ending, yet remain mesmerized by familiar details, filmed with a harrowing sense of urgency. It's as close to being in the White House situation room that night, watching a closed-circuit broadcast, as anyone could expect.
The second half of the film IS the film.
Source: http://www.rottentomatoes.com/m/zero_dark_thirty/
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One-two punch could be key in treating blindness
Apr. 9, 2013 ? Researchers have discovered that using two kinds of therapy in tandem may be a knockout combo against inherited disorders that cause blindness. While their study focused on man's best friend, the treatment could help restore vision in people, too.
Published in the journal Molecular Therapy, the study builds on earlier work by Michigan State University veterinary ophthalmologist Andr?s Kom?romy and colleagues. In 2010, they restored day vision in dogs suffering from achromatopsia, an inherited form of total color blindness, by replacing the mutant gene associated with the condition.
While that treatment was effective for most younger dogs, it didn't work for canines older than 1 year. Kom?romy began to wonder if the older dogs' cones -- the photoreceptor cells in the retina that process daylight and color -- might be too worn out.
"Gene therapy only works if the nonfunctional cell that is primarily affected by the disease is not too degenerated," he said. "That's how we came up with the idea for this new study. How about if we selectively destroy the light-sensitive part of the cones and let it grow back before performing gene therapy? Then you'd have a younger, less degenerated cell that may be more responsive to therapy."
So, Kom?romy and colleagues recruited more dogs with achromatopsia between 1 and 3 years old. To test their theory, they again performed gene therapy but first gave some of the dogs a dose of a protein called CNTF, which the central nervous system produces to keep cells healthy. At a high enough dose, its effect on photoreceptors is a bit like pruning flowers: It partially destroys them, but allows for new growth.
"It was a long shot," said Kom?romy, associate professor in MSU's Department of Small Animal Clinical Sciences.
But it worked.
"We were just amazed at what we found," he said. "All seven dogs that got the combination treatment responded, regardless of age."
While achromatopsia is quite rare, Kom?romy said it's a good model disease for other disorders affecting the photoreceptors, conditions that constitute a major cause of incurable blindness in dogs and humans. Those disorders affect individuals of both species in much the same way, so the combination treatment's promise isn't just for Fido.
"Based on our results we are proposing a new concept of retinal therapy," he said. "One treatment option alone might not be enough to reverse vision loss, but a combination therapy can maximize therapeutic success."
The research was funded by the National Eye Institute of the National Institutes of Health and the Foundation Fighting Blindness. Scientists from the University of Pennsylvania, University of Florida and University of Miami also participated in the study.
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The above story is reprinted from materials provided by Michigan State University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Andr?s M Kom?romy, Jessica S Rowlan, Amanda T Parton Corr, Shelby L Reinstein, Sanford L Boye, Ann E Cooper, Amaliris Gonzalez, Britt Levy, Rong Wen, William W Hauswirth, William A Beltran, Gustavo D Aguirre. Transient Photoreceptor Deconstruction by CNTF Enhances rAAV-Mediated Cone Functional Rescue in Late Stage CNGB3-Achromatopsia. Molecular Therapy, 2013; DOI: 10.1038/mt.2013.50
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.
Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/SbNBUtFPX6w/130409110008.htm
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Monday, April 8, 2013
Factories that ran on Korean cooperation go silent
SEOUL, South Korea (AP) ? A factory complex that is North Korea's last major economic link with the South was a virtual ghost town Tuesday after Pyongyang suspended its operations and recalled all 53,000 of its workers, cutting off jobs and a source of hard currency in its war of words and provocations against Seoul and Washington.
Only a few hundred South Korean managers remain at the Kaesong industrial complex, which has been run with cheap North Korean labor and South Korean capital and know-how for the past decade. The managers have not been forced to leave the facility just north of the Demilitarized Zone.
One manager said Tuesday that he and his colleagues are subsisting on ramen but planned to stay and watch over the company's equipment as long as their food lasted.
Pyongyang said Monday it would recall all 53,000 North Korean workers from the complex and would decide later whether to shut it down for good. The work stoppage at the biggest employer in the North's third-biggest city shows that Pyongyang is willing to hurt its own shaky economy in order to display its anger with South Korea and the United States.
Pyongyang has unleashed a torrent of threats at Seoul and Washington following U.N. sanctions punishing the North for its third nuclear test, on Feb. 12, and joint military exercises between the U.S. and South Korea that allies call routine but that Pyongyang sees as invasion preparation.
U.S. and South Korean defense officials have said they've seen nothing to indicate that Pyongyang is preparing for a major military action that it would certainly lose. Analysts say North Korea's rhetoric and actions are intended to force new, Pyongyang-friendly policies in South Korea and Washington and to boost domestic loyalty for Kim Jong Un, the country's young, still relatively untested new leader.
The Kaesong complex is the last symbol of inter-Korean rapprochement projects from previous eras of cooperation. Other projects such as reunions of families separated by war and tours to a scenic North Korean mountain became stalled in recent years.
Kim Yang Gon, secretary of the Central Committee of the Workers' Party of Korea, announced Monday on a visit to Kaesong that operations at the complex would be suspended. He said the facility has been "has been reduced to a theater of confrontation."
Kim said in a statement released by state media that North Korea will now consider whether to close the complex permanently. "How the situation will develop in the days ahead will entirely depend on the attitude" of South Korean authorities, it said. The message did not say what would happen to the more than 400 South Korean managers still at Kaesong.
Some North Koreans who worked overnight shifts at Kaesong were still there Tuesday morning, but South Koreans said those scheduled for day shifts didn't show. A North Korean woman at Kaesong said in a telephone call that she planned to return home now that her night shift was done.
One of the South Koreans who remained at Kaesong on Tuesday said he planned to stay there until food runs out. He said he and four other colleagues had been living on instant noodles.
"We haven't had any rice since last night. I miss rice," he said Tuesday morning. "We are running out of food. We will stay here until we run out of ramen."
In noting the shutdown, the U.S. referred to a Central Committee of the North's ruling Worker's Party statement a little more than a week ago, in which it described the economy as one of the nation's top two priorities. The other is building nuclear weapons.
State Department spokesman Patrick Ventrell said closing the complex "would be regrettable, given that more than 50,000 North Korean people are employed there, and it would not help them achieve their stated desire to improve their economy and better the lives of their people."
South Korea's Unification Ministry, which is responsible for relations with the North, issued a statement saying South Korea will act "calmly and firmly" and will make its best efforts to secure the safety of South Koreans at Kaesong.
North Korea has threatened to fire nuclear missiles at the U.S. and claimed it had scrapped the 1953 armistice that ended fighting in the Korean War. Last week it told foreign diplomats based in Pyongyang that it will not be able to guarantee their safety as of Wednesday. Embassy workers appeared to be staying put. There have also been worries in Seoul of an even larger provocation from Pyongyang, including another possible nuclear test or rocket launch.
The barrage of North Korean threats has made North Korea increasingly isolated. China, its most important ally, expressed unusual disappointment when Pyongyang announced last week that it was restarting a plutonium reactor to produce more nuclear-bomb fuel.
Even before Monday's announcement, Pyongyang had been allowing operations at the Kaeson complex to wither. Last month it cut the communications with South Korea that had helped regulate border crossings at Kaesong, and last week it barred South Korean workers and cargo from entering North Korea.
Operations had continued and South Koreans already at Kaesong were allowed to stay, but dwindling personnel and supplies had forced about a dozen of the more than 120 companies operating at Kaesong before North Koreans were told to stop working there.
North Korea briefly restricted the heavily fortified border crossing at Kaesong in 2009, but manufacturers fear the current closure could last longer.
South Korea's Unification Ministry estimates 53,000 North Korean workers in Kaesong received $80 million in salary in 2012, an average of $127 a month paid in U.S. dollars. The Unification Ministry says Kaesong accounted for nearly all two-way trade between the Koreas. Cross-border trade, including supplies entering Kaesong and finished products coming out, approached $2 billion annually.
North Korea objects to portrayals in the South of the zone being crucial to the impoverished country's finances. Kim said North Korea "gets few economic benefits from the zone while the south side largely benefits from it." North Korea has also expressed outrage over South Korean discussion of military rescue plans in the event Pyongyang held the managers hostage.
___
Associated Press writer Hyung-Jin Kim contributed to this report.
Source: http://news.yahoo.com/factories-ran-korean-cooperation-silent-022521784--finance.html
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