What is CAPTCHA?

    A CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot. For example, humans can read distorted text as the one shown below, but current computer programs can't:

    The term CAPTCHA (for Completely Automated Public Turing Test To Tell Computers and Humans Apart) was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford of Carnegie Mellon University.

    CAPTCHAs are used in attempts to prevent automated software from performing actions which degrade the quality of service of a given system, whether due to abuse or resource expenditure. CAPTCHAs can be deployed to protect systems vulnerable to e-mail spam, such as the webmail services of Gmail, Hotmail, and Yahoo! Mail.

    CAPTCHAs are also used to minimize automated posting to blogs, forums and wikis, whether as a result of commercial promotion, or harassment and vandalism. CAPTCHAs also serve an important function in rate limiting. Automated usage of a service might be desirable until such usage is done to excess and to the detriment of human users. In such cases, administrators can use CAPTCHA to enforce automated usage policies based on given thresholds. The article rating systems used by many news web sites are another example of an online facility vulnerable to manipulation by automated software. As of 2010, most CAPTCHAs display distorted text that is difficult to read by character recognition software.

    Because CAPTCHAs rely on visual perception, users unable to view a CAPTCHA due to a disability will be unable to perform the task protected by a CAPTCHA. Therefore, sites implementing CAPTCHAs may provide an audio version of the CAPTCHA in addition to the visual method. The official CAPTCHA site recommends providing an audio CAPTCHA for accessibility reasons, but it is not usable for deafblind people or for users of text web browsers.

    Even audio and visual CAPTCHAs will require manual intervention for some users, such as those who have disabilities. There have been various attempts at creating more accessible CAPTCHAs, including the use of JavaScript, mathematical questions ("how much is 1+1") and common sense questions ("what colour is the sky on a clear day"). However, these types of CAPTCHAs do not meet the criteria for a successful CAPTCHA. They are not automatically generated and they do not present a new problem or test for each attack.

    Some researchers promote image recognition CAPTCHAs as a possible alternative for text-based CAPTCHAs. Computer-based recognition algorithms require the extraction of color, texture, shape, or special point features, which cannot be correctly extracted after the designed distortions. However, human can still recognize the original concept depicted in the images even with these distortions.

    A recent example of image recognition CAPTCHA is to present the website visitor with a grid of random pictures and instruct the visitor to click on specific pictures to verify that they are not a bot (such as “Click on the pictures of the airplane, the boat and the clock”). Image recognition CAPTCHAs face many potential problems which have not been fully studied.

Sources: http://www.captcha.net/ http://en.wikipedia.org http://www.rizzotees.com/ http://www.google.com

Nokia Phone Concepts

Nokia Morph

Unveiled in 2008, the Morph was the product of a joint study into the future of mobile phones by Nokia and the University of Cambridge’s Nanoscience Centre.

It tops our list because some of its super cool ideas are just mind-blowing! Its flexibility for starters; it could be worn around the wrist or held up to the face. The Morph would also contain self-cleaning surfaces that absorb solar energy so it can recharge the phone’s battery. Last but by no means least, it looks like something straight out of a futuristic Sci-Fi film!!!

Nokia 888

Dubbed the Nokia 888, this concept phone is ultra-lightweight, wafer thin and incredibly flexible. It is powered by liquid battery and has a touch screen display. What more could you want?

Nokia E-Cu

Scaling the dizzy heights at number 2, is a concept phone that uses your body heat to charge itself! We’ve all been there, our mobile phone is about to die and we can’t get to a charger in time. Well the Nokia E-Cu would solve this problem. Built with a thermo generator, it could convert heat into energy. The idea is that by putting the phone in your pocket, you will get a charge, so by our logic, putting it next to a radiator would give you a turbo-charge it!

Nokia Kinetic Concept

Designed by Jeremy Innes-Hopkins, the Nokia Kinetic concept phone turns digital information into kinetic energy by way of the electromagnet in its base. In normal speak this basically means that when a call is received, the weight in the base can be shifted and the phone rises. Don’t want to take the call? Just tap it back down. How cool is that?!

 Nokia E97 Envelop

When I look at the E97 Envelop concept phone from Nokia, I got convinced that a man’s imagination has no boundaries.
The Nokia E97 Envelop is definitely designed to impress. How nice it is to see a new Nokia concept phone, even if the mobile phone is not materialized by the company itself, but thanks to all the talented people it become possible to imagine what a Nokia phone in the future might look like.

With dark and smoothed edges, the Nokia E97 has a unique liquid crystal screen that comes out of the keyboard and can be removed from the cell, you simply pull the screen like a paper envelope, and the unplugged display can be used as a storage device, a flash drive for example. The smartphone features a AZERTY keyboard. 

Plus, the phone works with two SIM cards (sim) simultaneously.The concept of this mobile with a pull-out LED display that comes out of a keyboard, and that can be removed from the phone itself was developed by a young student named Fabien Fabien Nauroy (France) and he called this phone E97 Envelop.

Nokia UNIX

Talk about a concept cellphone which brings things to a whole new level with the Nokia Unik. Designed by French designer Clement Logereau, the Unik comprises of 152 small squares, where the handset is able to transform itself by virtue of adding in new squares that are different in material and color. These squares can be added after a purchase from Nokia stores, leacing you with a choice of metal, transparent and rubber squares. Something tells us that the Nokia Unik will remain just that – a unique concept.

Sources:

http://blogs.nokia.com

http://www.ubergizmo.com

How Acer's Dual Screen Laptop Works

The $1,300 Acer Iconia laptop is certainly unique. The machine features two 14-inch touchscreens instead of the tried and true screen-and-keyboard combination, while retaining the same form factor as a standard laptop. 






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