We've Finally Figured Out What Makes LED Bulbs So Inefficient

LEDs should be lighting the way to a greener future: They use 75 percent less energy and last 25 times longer than incandescent light bulbs, and they do so at a cooler temperature. But right now, we mostly use LEDs in electronics, because they have a bit of a drooping problem: at higher currents, the amount of light they produce takes a nose-dive.
The efficiency droop has baffled scientists for years, but researchers at the University of California, Santa Barbara and France's École Polytechnique say they've finally solved the mystery.
Their work, published in a forthcoming issue of the Physical Review Letters, identifies the source of the droop as a process called Auger recombination, a non-radiative process that produces heat. Previous research at UCSB theorized that Auger recombination might be the culprit, but this is the first study to measure the effect conclusively.
LED-based lights contain a microchip with a positive-type and a negative-type semiconductor made of gallium nitride. Between the two, in a quantum well, the negative electrons from one semiconductor and the electron holes from the other combine, producing a photon of light. When you apply more electricity, it produces more photons--to a point. In low power situations, like in your cell phone, the process works great. But when you raise the current up to the level it takes to light a room, nitride-based LEDs stop producing photons at the same rate. According to the research from UCSB's Center for Energy Efficient Materials, it's because the electrons collide with each other and lose their energy through heat instead of light.
If we could make LEDs that circumvent that issue, they could replace compact fluorescent lights as the energy-efficien

t bulb of the future. Theoretically, LEDs should produce about 300 lumens per watt, making them three times more efficient than CFLs, as well as easier to dispose of since they don't contain...

The growing fear of having your brain hacked -- for real

With all these new brain scanners on the market, it's becoming increasingly important for manufacturers to make sure they're safe.

Brain-computer interfaces, like the ones produced by NeuroSky and Emotiv, allow users to control objects and video games with their thoughts. The growing fear is that third party-developer

s could build apps that masquerade as games — but actually harvest sensitive information from the user. Or they could simply be hacked into from unknown external sources. Writing in SF Chronicle, James Temple highlights the concerns:
In early 2009, hackers inserted malicious code into an Epilepsy Foundation message board that embedded flashing images into hundreds of posts.

An untold number of epilepsy patients clicked on otherwise normal-looking headlines, only to find themselves staring at kaleidoscopic animations. For a handful, the images triggered migraines or near seizures, according to reports at the time.

The episode might have represented one of the first brain hacks, a computer attack on the mind. But security researchers say it's unlikely to be the last.

In fact, as brainwave sensors for games and implantable neural devices for diseases become more common and sophisticated, a host of troubling possibilities arise. Early research suggests that hackers might be able to use these tools to extract sensitive information from our brains, like ATM passcodes. From there it's not too far a leap to triggering physical movements or perhaps even inserting ideas.

"You could use these to directly interact with the brain," said Ryan Calo, assistant law professor at the University of Washington focused on privacy and robotics, in a recent presentation at Stanford. "You could get up to all sorts of mischief." And indeed, a number of security experts say the time has come for manufacturers to protect consumers from these sorts of threats.

There's lots more in Temple's article, including a UC...

Cyclist’s Virtual Safety Lane

Do you love cycling? If you have answered in the affirmative, then surely you would do your very best to make your travel arrangements around the rest of the bicycle-friendly public transport around town, especially when there are great distances to travel between your home and the destination of choice. Sometimes, you might have to travel in the wee hours of the morning, or late into the night, and those are dangerous times for cyclists since visibility is extremely low. Well, perhaps if you had the $39.95 Cyclist’s Virtual Safety Lane, things might brighten up for you?

The Cyclist’s Virtual Safety Lane works this way – it is mounted to your bicycle’s seat post, where it will then project a couple of 5-milliwat red lasers onto the ground, which will generate a virtual bicycle lane. This offers motorists with a visual indicator of a cyclist’s riding width, helping you visually increase the safety margin around yourself during those pre-dawn or dusk rides. Oncoming vehicles, as well as those from behind, can actually see you even with their headlights turned on, from over a mile away. The 6′-long lane will begin mid-cycle at the seat post and extends all the way behind, while another 5 more red LEDs help increase your visibility as a standard blinking taillight. The Cyclist’s Virtual Safety Lane is powered by a couple of AAA batteries.

Free Wi-Fi service on trains to launch today starting with the New Delhi-Howrah Rajdhani express

During the Rail Budget announcement back in February, Railway Minister Pawan Kumar Bansal had revealed plans to introduce free Wi-Fi on select trains. TheBusinessLine

has now posted a report saying that the free Wi-Fi service will be launched today on the New Delhi-Howrah Rajdhani.

The Wi-Fi service is being provided to allow passengers to browse the Internet, check emails, chat or use YouTube when in the train. Porn and other illegal sites though will be blocked by default. Passengers will have to provide their mobile number or their PNR number to receive a password through SMS, which will give them access to the Wi-Fi network. A speed of 4Mbps is being offered which will be shared among the passengers.

The Railway Ministry plans to offer free WI-Fi services on 50 other trains by the end of this year which will include the Rajdhanis, the Shatabdis and the Duronto express trains among others.