Reversible data transfers from light to sound

As a step towards designing tomorrow's super-fast optical communications networks, a Duke University-led research team has demonstrated a way to transfer encoded information from a laser beam to sound waves and then back to light waves again.

Swapping data between media like this would allow information to be captured and retained for very brief intervals. Data could be stored within pockets of acoustic vibration created when laser beams interact along a short strand of optical fiber, the team reported in the Dec. 14, 2007 issue of the journal Science. The Duke experiments address a barrier to efforts at developing computer networks that can run on light instead of electrons. "The real gist of the work is how to create a memory for optical pulses," said Duke physics professor Daniel Gauthier, the report's corresponding author. Computers in use now manipulate the flow of electrons to shunt the data they carry into memory. But light has proved to be stubbornly resistant to similar traffic controls. "We don't have random access memories for light the way electronic computers do," Gauthier said. The new method, suggested by Gauthier's postdoctoral research associate Zhaoming Zhu, uses a phenomenon called "stimulated Brillouin scattering." Opposing laser beams passing though each other along an optical fiber create acoustic vibrations known as phonons within the glass. "To efficiently create such acoustic waves, you have to have two laser beams of slightly different frequencies interacting with each other," Gauthier said. In a series of experiments at Duke, Zhu found that if he encoded information onto one of those laser beams, the data could be imprinted on newly-created phonons. Such phonon sounds are much too high-pitched for humans to hear, Gauthier said. Zhu, the Science report's first author, documented that phonons could retain the data for as long as 12 billionths of a second. The information could then be successfully re-transferred from sound to light again by shining a third laser beam through the fiber.

"While short by human standards, 12 billionths of a second is long in comparison to the time scales used in optical data transmission," said coauthor Robert Boyd, a professor of optics and physics at the University of Rochester's Institute of Optics. While Zhu conducted the experiments, Gauthier and Boyd examined the findings' theoretical underpinnings. The work was funded by the Defense Advanced Research Projects Agency's Defense Sciences Office Slow-Light Program. The new method works at room temperatures and at wavelengths of light compatible with optical fibers already used in telecommunications, giving it several advantages over competing techniques for manipulating light. More work will be needed before this approach becomes workable in optical computation, Gauthier acknowledged. First, the power used for the write and read pulses is about 100 watts, "rather high for any type of telecommunications application," he said. "The other issue is that we're only storing the data for about 10 nanoseconds," Gauthier added. "There may be a few applications where such short storage times would be okay. But, for many applications, you would like to store it for seconds." In their report, the authors suggest other kinds of fiber optic materials that might yield better results. "I'm hoping that other scientists around the world will come up with new ideas based on our work," Gauthier said. "The Duke team will also be pushing the state of the art in this field with our own ideas." Source: Duke University

Suicide bombers may target Indian missions in Pak

December 14, 2007 14:34 IST
Indian and American diplomatic missions and VVIPs including President Pervez Musharraf [ and former premier Benazir Bhutto might be targeted in "a spate of suicide attacks by terrorists" in Pakistan, intelligence agencies have warned.
Terrorists based in the restive northwestern tribal areas bordering Afghanistan and the Swat valley in North West Frontier Province are planning to carry out suicide attacks in collusion with the al Qaeda, said a secret report prepared by the National Crisis Management Cell.
"The high value targets include the top government hierarchy, top politicians including former religious affairs minister Ejazul Haq and the Attock Oil Refinery in Rawalpindi.
Besides the US and Indian embassies, their consulates and several other religious and political personalities are also on the hit list," the Daily Times quoted the report as saying.
The report, titled 'Threat to VVIPs, politicians, foreign missions and military installations', said terrorists could carry out suicide attacks disguised as women or as military or police personnel.
"Furthermore, five suicide bombers have already entered the NWFP to move to their target areas," it said.
"The emphasis needs to be on the security of foreign diplomats, foreigners living in Pakistan, and the Christian community who would attend Christmas prayers at different churches in Rawalpindi and Islamabad. It is apprehended that hardcore religious elements may try to disrupt the New Year celebrations," the report said.

Expert speak: Useful tips to beat PC hackers

You do it almost everyday. You login into your computer, send e-mails, open attachments from friends and strangers, shop online, transfer money using your banks secured payment gateway, chat with friends and upload personal information on social networking sites.
But have you ever given a thought to someone who is keeping a close watch on all your online activities. Someone, somewhere in some corner of this planet trying to get inside your computer and filch one of the most important resources of information age: personal data.
Data that can be abused to make purchases online, send malicious programmes to all those on your contact list and many such things to harm you. Welcome to the age of hackers (these are people who try to gain access to your computer using various hacking tools and misuse your personal data) and spies lurking on the vast Internet highway.
But don't worry. There are ways in which you can beat the hackers.However, when it comes to security nothing is 100 per cent secure. Loads of exploits are developed everyday. Updating the knowledgebase should be a regular process. Following could be few of the many measures that could be taken to protect your computer and all things that you do online:
~ Install the latest antivirus software (I recommend Kaspersky, Eset Nod32, Quickheal, F-Secure) on the computer and never ever disable or turn it off. Install a personal firewall (www.sygate.com and www.zonelabs.com offer free versions) and Spyware Checker (I recommend Spybot Search & Destroy).
~ Keep updating antivirus/anti spywares at least every 15 days. Use separate Trojan removers like anti Trojan shield if possible. Full system scan with your anti virus at least once in a week or better set it to scan periodically and give a small interval say every Friday (the day may vary according to your choice).
~ There are a few free online scanners available at http://housecall.trendmicro.com or http://www.kaspersky.com/kos/eng/partner/us/kavwebscan.html, and http://support.f-secure.com/enu/home/ols.shtml.
~ Get System's health checked regularly at http://www.pcpitstop.com/. The site checks the overall system health, tunes up the system and finds out the vulnerabilities. It's a free service.
~ Don't ever download or open attachments whose source you are not certain about. Even if the source is trusted, see if the content is relevant. Even non-executable files like *.Doc files can contain macro viruses and Trojans. There are some special sort of programmes called worms, which don't need human interaction. You just open a mail or visit any website and that's it. So always stay alert. Avoid opening e-mail attachments that contain '.vbs', '.scr', '.exe', or '.pif' file extensions. Files that end in these extensions are most likely to contain some sort of virus.
~ Web browsers like Fire Fox, IE 7 & Opera offer good security features. Test your Web Browser for Vulnerability at http://bcheck.scanit.be/bcheck/.
~ Never download any files specially executables over P2P (peer-to-peer) sharing networks, because you cannot be absolutely certain what they are. P2P file sharing programmes can lead to the installation of a lot of adware and spyware. Try downloading executables from authentic and well-known sites; don't just download files from anywhere.
~ Try not to visit porn sites, Warez, sites of cracks and serials because most of them have hell lot of latest spywares, Trojans and viruses .One visit and you are gone if your virus definitions are not up to date.
~ Be familiar with the installed programmes on your computer. If you notice a new programme installed, which you didn't in the first place, possibilities are that it might be something malicious.
~ Read the installation agreements carefully when you download something from the Internet. Pay attention to the terms and conditions or EULA (end-user license agreements) of the program being installed. Reference to third party installation should be given more attention. Some EULA's tell you that, if you install the program, you have also agreed to install some spyware with the software. Do check the independent sources as some EULA's do not mention about the Spywares.
~ Back up your computer data on a regular basis, at least weekly. Copy your important documents and files onto a floppy disk, removable drives, CD or a DVD for safekeeping. Don't wait for the disaster to happen, take the precaution before hand. Create system restore points periodically
~ Use e-mail encryption like PGP to send important information via emails. Don't send important information in plain text.
~ Never respond to unsolicited e-mail. To those who send spam, one response or 'hit' from thousands of e-mails is enough to justify the practice. Additionally, it validates your email address as active, which makes it more valuable, and therefore opens the door to more spam.
~ Beware of phishing attacks. Sites like www.antiphishing.org offer latest updates on phishing along with good security tips
~Don't chat with strangers just for fun. Don't ever accept any file, especially executables from an unknown person on chat. Don't click on any links given by someone you don't know.
~ Do not accept links or downloads from strangers even if it is tempting. There have been cases where spywares like Trojans, keyloggers etc. have been hidden in simple picture files with '.jpg' extensions. You never really know what is contained inside a file which looks attractive.
Today people use binders to club two different files and send you the mixture. Once you click on the file both file gets executed.
~ Be cautious while displaying your profile, especially your personal details, photographs, videos and contacts on social networking sites. Your profiles and contacts may be misused by other people.
~ Install parental control softwares like netnanny that helps you choose what the kids see on the Internet and monitor the activities of children. For more details visit http://www.microsoft.com/athome/security/children.
Wireless security
~ If you have a wireless network, turn on the security features: Use MAC filtering, turn off SSID broadcast, and even use WEP/WPA/WPA2 with the biggest key you can get.
Online shopping safety tips
~ While purchasing online, look for signs that online purchases are secure (SSL secured sites or 128 bit encryption) like Ebay.co.in. At the point that you are providing your payment information a golden coloured lock appears (for SSL secured sites) or the beginning of the Web site address should change from http to shttp or https, indicating that the information is being encrypted -- turned into code that can only be read by the seller.
Your browser may also signal that the information is secure with a symbol, such as a broken key that becomes whole or a padlock that closes.
~ Carefully use credit card and online banking for online shopping. Check your credit card and bank statements at regular intervals. Notify the bank immediately if there are unauthorised charges or debits. Avoid using credit card details and online banking on public computers and in cyber cafes. It is very unsafe because most of them are infected with viruses, Trojans and key stroke loggers.
Banks such as HDFC [Get Quote] have launched their services like Net Safe to create temporary credit cards with a limited value to transact online. This way, in the worst case scenario, your damages are limited.
Password security
~ Use two different passwords. One for mail, work and other important access and other for routine purposes like subscribing to websites or public viewing. But remember to switch between them when you start doing transactions after mere browsing. Create another e-mail ID providing false information and crazy usernames like 'whitecat_4u', 'kkk320' etc. which you use exclusively for subscription to sites. That will prevent spam from coming to your main ID.
~ Create a difficult-to-guess password by taking the first alphabet from each word of a phrase. What is a good password? It is a password which is at least 8 characters long, not easily guessable, contains mixture of uppercase and lowercase letters as well as numbers, and preferably contains special characters like $, *, %, !, * etc. Some examples of a good password are: &(^.1234*cRack&.^).
~ Always use alphanumeric passwordwith special characters and try to adopt phrasing technique to construct passwords which are easy to remember, hard to guess and impossible to crack. Create a unique acronym. Never use a dictionary based password like guest, home etc. It takes little time for a good cracker to crack the password