Thursday 13 January 2011

Blogger - How to publish a post directly from Google docs

1. Open http://www.google.com/ and at the top left corner click on “more – Documents”

2. Then login to GoogleDocs with your Gmail credentials and you should see the “All Items” section with your google documents listed.

3. Left click on the document you would like to publish on Blogger.

4. When the document opens go to the window’s top right corner and click on the Down arrow (next to the Share button) - “Publish  as web page” – “Post to blog (This document has not been published to your blog)”


*Note: The article that you publish to your blogspot directly from google docs should be a text document (.txt, .doc, .docx, etc.) 

Wednesday 12 January 2011

Cribsheet - Quantum Computers (for Beginners)

Cribsheet #15 Quantum Computing

Seed’s Tear-Outable Tool for Living in the 21st Century

   Intel cofounder Gordon Moore famously observed nearly half a century ago that the number of transistors economically crammed into a single computer chip was doubling every two years. This trend toward miniaturization is seen throughout the history of modern computing. Today elements of microchips are only tens of nanometers in size, and if miniaturization continues, microchip components will eventually reach atomic scales, where their properties will be dictated by quantum mechanics.

   Miniaturization may ultimately lead to quantum computers, which use quantum effects to perform calculations. Quantum computers could, in principle, solve certain problems exponentially faster than the best known “classical” methods with far-reaching consequences for cryptography and the simulation of quantum physics. Simple quantum computers have already been built, but most experts believe robust and powerful systems remain many years away.

 

The Key Questions of Quantum computing: What is a quantum computer, and how does it differ from modern computers? How can we use quantum computing?

 

Quantum Computing 101

 

Both classical and quantum computers perform calculations by manipulating information. Classical computers represent information as binary digits, or bits, which can have values of either 0 or 1. Quantum computers represent information as quantum bits, or qubits. Many different physical objects can be used as qubits, such as atoms, photons, or electrons. Paradoxically, a qubit can represent 0 and 1, as well as other possible values, at the same time, in what is called a quantum superposition. This allows a qubit to simultaneously use many more informational states for computation and is responsible for quantum computing’s advantages over classical computing. In the illustration above, an atomic spin represents a qubit. An “up” spin corresponds to 0; a “down”spin equates to 1. A quantum superposition encompasses 0, 1 and all possible values in between.

 

 

INTERFERENCE PATTERNS

 

The latent possibilities within a superposition can actually interfere with each other, constructively reinforcing or destructively canceling each other to form the final definite state. The programmer of a quantum computer must choreograph the calculation in such a way that computational paths leading to a “wrong” answer will destructively interfere with each other, canceling each other out and leaving only the “right” answers to be observed.

 

 

 

FINDING AN ANSWER

 

The ability of quantum objects to simultaneously hold multiple, seemingly conflicting values is at the heart of quantum computing. This state is called a quantum superposition (at right). Superpositions occur all the time at the quantum level. In fact, any isolated quantum object like an atom or a photon is in a superposition. But as soon as the object interacts with something else, such as another atom or photon, the superposition is liable to collapse. The collapse of a superposition is called decoherence. Decoherence is essentially an act of measurement, where all possible states in the superposition collapse into the one ultimately observed. If the quantum computer’s qubits suffer too much decoherence before the calculation is completed, the information will be irretrievably lost and the probability of producing a correct answer becomes essentially zero.

 

 

 

 

 

 

 

 

 

 

 

             

 

Fig

 

 

1.    The encryption vital for modern secure communications assumes that factoring large numbers in a reasonable amount of time is beyond the capabilities of today’s commercial computers. In 1994 computer scientist Peter Shor devised an algorithm allowing a quantum computer to quickly factor large numbers. Thus, a powerful quantum computer could break the world’s dominant encryption schemes, resulting in the need for new security methods. For perspective, today’s quantum computers are scarcely powerful enough to factor a number like 15. At right, a schematic illustration outlining how Shor’s algorithm works:

2.    Hundreds or thousands of qubits would be needed to factor very large numbers. For convenience, here we’ve illustrated only four.

3.    Place the qubits in a superposition over all of their possible configurations in preparation for initiating a quantum interference pattern.

4.    Choreograph quantum interference to allow paths to correct answers to reinforce each other.

5.    Perform a measurement, collapsing the qubits’ superposition. By repeating these steps and combining the results, we can reliably obtain the factors of a very large number.

 


What Problems Can a Quantum Computer Solve?

 

 

 

Computer scientists classify a problem’s difficulty by the number of computational steps an algorithm requires to solve it. Problems that a classical computer can quickly solve are called P (polynomial time) problems. In P problems, as the problem size n increases, the number of steps to solve it grows polynomially, for instance by n2. Determining whether a number is prime is an example of a P problem. NP (nondeterministic polynomial time) problems consist of all problems for which the answers are easy to check, even though finding those answers may take an exponential number of computational steps, such as 2n. Every P problem is also an NP problem, but computer scientists believe that not all NP problems are P problems. BQP (bounded-error, quantum polynomial time) problems are the class of problems that quantum computers can efficiently solve. Factoring the product of two large prime numbers is an example of a problem that is both an NP and a BQP problem. Though no one knows for certain, it appears that BQP does not include most NP problems. This means that for most NP problems, quantum computers may offer no significant advantages over classical computers.

 

THE ISSUE: Can we build a sophisticated quantum computer?

 

A company called D-Wave Systems has exhibited what it controversially calls the world’s first commercial quantum computer, but most experts treat these claims with considerable skepticism. Some of the best minds in physics today are struggling to build simple quantum computers, and computer scientists are still seeking their ideal applications. It seems that even if practical, powerful quantum computing existed today, we probably wouldn’t know how to best use it. Ironically, if building sophisticated quantum computers turns out to be impossible in principle, this may be the biggest breakthrough of all, as it would imply that our fundamental understanding of the quantum world is incorrect.

 

SOUNDBITE

 

Quantum computers could theoretically revolutionize our ability to solve certain kinds of computational problems, but first we must discover how best to build and use them.

 


Sunday 9 January 2011

How to watch videos restricted in your country using Tor and portable Firefox (explained for BBC iPlayer videos)

 If you try to open UK videos that are restricted for watching outside UK (the examples below) and you are not located in UK you will get a message that the videos are not available for watching in your country.


Fortunately there is a solution for this issue, I have done some research on the Internet and found several articles, tested some options and wrote all the steps that should be followed.

1. Download the Tor Browser Bundle (portable package) on your computer

Go to http://www.torproject.org/download/download.html.en and download the latest stable version of Tor Browser Bundle to your computer. Run the executable: tor-browser-1.3.15_en-US.exe and then you should see a folder with a name Tor Browser located in the same folder where you have saved the .exe file.

In order to run the Tor portable software you should open the Tor Browser folder and click on "Start Tor Browser.exe" 

2. Change Tor settings for watching flash videos

Open Tor, then portable Firefox browser will start.
Click on Tools - Add-ons - Extensions tab - Torbutton - Options - Security settings tab - uncheck the box "Disable plugins during Tor usage". Click on OK.

3. Install the Adobe Flash Player on Firefox Portable (Tor)

3.1. If you already have Firefox and Flash installed on the computer

If you are using Windows 7 64-bit go to C:\Windows\SysWOW64\Macromed\Flash
(for Windows 7 32-bit: C:\Windows\system32\Macromed\Flash)
Copy the files:

flashplayer.xpt
NPSWF32.dll

and paste them into your portable Tor Firefox browser plugins folder (for me it is: C:\Users\encounter\Desktop\Tor Browser\FirefoxPortable\App\Firefox\plugins)
Restart the portable Firefox

3.2. If you don't have Adobe Flash installed on your computer (or if you want to install the latest flash version on the portable Firefox)

If you are using Firefox, right click on the link: http://fpdownload.macromedia.com/get/flashplayer/xpi/current/flashplayer-win.xpi and click on "Save Link As" (for IE: "Save Target As")
Then save the .xpi file on your computer.
 

Change the file extension from .xpi to .zip, create a new folder and extract the .zip file there. Copy the 2 files: 

flashplayer.xpt
NPSWF32.dll

into the Tor Portable Firefox plugins folder  (for me it is: C:\Users\encounter\Desktop\Tor Browser\FirefoxPortable\App\Firefox\plugins)
Restart the portable Firefox.
Now you are able to watch Flash videos in the Tor Portable Firefox browser

4. Settings for watching BBC iPlayer videos restricted in your country (Configure Tor to use UK as an exit node)

4.1. Find the UK exit nodes with the highest bandwidth

Start Tor (click on "~\Tor Browser\Start Tor Browser.exe", for me it is C:\Users\encounter\Desktop\Tor Browser\Start Tor Browser.exe)
In the Vidalia Shortcuts section click on View the Network. Sort the nodes according to their Country by left clicking in the cell above the flags column. Then scroll down, find the UK flag and highlight the first node (the first node for every country should have the highest bandwidth).
At the bottom right corner window you should see nodes details starting with its name and status (Online). Copy the name.
Follow the same procedure and copy the 2nd and 3rd UK node names in the list.
Save those names into a text document because we are going to need them for 4.2

4.2. Modify the Tor configuration file (torrc)

Open the "~\Tor Browser\Data\Tor\torrc" file with Notepad
(for me it is C:\Users\encounter\Desktop\Tor Browser\Data\Tor)

* You can also check the exact torrc file location by starting Tor, click on "Settings - Advanced tab" and then click on the Browse button next to the Tor configration file path. Copy the full path to the torrc file from the address bar and paste it into a new Windows Explorer. 

Add the 2 lines below at the bottom of the document:

ExitNodes server1, server2, server3
StrictExitNodes 1

Replace the server1, server2, server3 with the highest bandwidth UK nodes (the ones we have copied in 4.1)
Save the changes you made to the torrc file by clicking on File - Save.
Restart Tor, the portable Firefox browser will launch. Now you can go to the BBC iPlayer TV (http://www.bbc.co.uk/iplayer/tv) and watch some restricted for your country videos.  

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*Note: If you want to download some region restricted videos to your computer, you can install the Video DownloadHelper Firefox add-on (https://addons.mozilla.org/en-US/firefox/addon/3006/)on the portable Tor Firefox browser. Unfortunately the DownloadHelper could not be used for BBC iPlayer videos, but it works for region restricted youtube videos. 
I tried to download one youtube restricted for my country video using the portable Firefox and RealPlayer plugin installed in a way similar to the Flash plugin installation in 3.1 , but received an error "Unable to download" even though the RealPlayer in my native Firefox (installed on the computer) was able to download videos from youtube.

Here are also the steps I have followed for the RealPlayer plugin installation on the portable Firefox browser:

For Windows 7 64-bit open the folder: 
C:\Program Files (x86)\Real\RealPlayer\Netscape6
Copy the file "nppl3260.xpt" and paste it into your portable Firefox components folder (for me it is: C:\Users\encounter\Desktop\Tor Browser\FirefoxPortable\App\Firefox\components)
Then copy the file "nppl3260.dll" and paste it into your portable Firefox plugins folder (for me it is: C:\Users\encounter\Desktop\Tor Browser\FirefoxPortable\App\Firefox\plugins)
Restart the portable Firefox browser and the realpayer plugin download window should appear when you play some videos (but probably you will not be able to download the videos with it)

Saturday 8 January 2011

How to access and download Zamunda.net torrents from abroad using Proxy


Note: This tutorial is for all of you guys that have Zamunda accounts and are living outside Bulgaria (I have written this article since the zamunda website is not accessible from abroad). 


1. Open any of the Bulgarian proxy websites below


, copy the Zamunda URL: http://zamunda.net/ in the empty box and press the Enter button on your keyboard.
Then the Zamunda website will open, you should log in, download the torrent file (.torrent) on your computer and open it with the default torrent client (for ex. uTorrent). If the download process does not start in 5-10 minutes (even there are many seeders listed on the website), please go to step 2. Otherwise, just wait for the torrent to be downloaded and then enjoy it.


2. Modify the torrent client (uTorrent) settings for downloading via Bulgarian proxy server.


From the websites below you should copy one of the free Bulgarian proxy servers IP Address (four set of numbers separated by dots) and port number (this is the number following the proxy IP address and the semicolon, most common ports are 8080 & 3128)

* I would suggest for you to look for anonymous proxy with the smallest average response time (latency) that has been updated most recently.
    

Open the torrent client (uTorrent) and go to Options – Preferences – Connection
On the Proxy server section, click on the drop-down menu next to “Type” and choose HTTP. In the “Proxy” box enter the proxy server IP Address and in the “Port” box enter the proxy port number . You should also check “Use proxy for peer-to-peer connections”, then click on OK.
Voila!

Used Sources: