Friday, November 25, 2005

Case sensitivity of URLS

Case sensitivity of URLS
 
WWW.YAHOO.COM is same as www.yahoo.com,
becasue, DNS servers which resolve the domain names are NOT case sensitive.
 
But, URLS like may be or may not be www.google.com/help is case sensitive.

If you type www.google.com/HELP, you may get an error,
depending on the operating system of server in which the file is stored.
If the file is hosted in Linux Servers, you will get an error if
www.google.com/HELP is typed.
But, it will be accepted, if the file is stored in a server running Windows Servers.
So, it will be better to type in correct case, if the target server OS is not known.
 
bharath
 


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Sunday, November 13, 2005

Ideas to deflect Earth-bound Asteroids

Simple ,
1. Put a big spaceship near it and let its gravity pull the asteroid off course.
2. Paint the asteroid white
3. Deflect by bursting small nuclear bombs nearby
or 
4. The usual Hollywood way of blowing up the body with Nuclear power.The problem with this idea is that some pieces can still make it to Earth in case of nuclear explosion.
 
For detailed explanation , read this article from NewScientist.com below
bharath
 
 
--------------------------------------------------------------------------------------------------------------

18:00 09 November 2005

NewScientist.com news service

Zeeya Merali

 

NASA scientists have come up with a surprisingly simple yet effective way to deflect an Earth-bound asteroid – park a large spacecraft close by and let gravity do the work.

Previous suggestions have focused on deflecting an incoming asteroid with nuclear explosions. But NASA experts believe a "gravity tractor" should be able to perform the same feat by creating an invisible towline to tug the rock off its deadly course.

"Most people think of the Hollywood treatment – throw a nuclear weapon at it," says Edward Lu, a NASA scientist and astronaut who developed the idea. But this would produce shattered pieces, some of which might still head towards Earth. "That’s the blast-and-hope strategy," Lu adds.

Pots of paint

Another proposal is to detonate nuclear bombs close to the asteroid. The resulting blast of radiation should nudge it off track but there is the same risk of wayward fragments if the asteroid shatters.

A more novel idea is to paint the surface of the asteroid white. This should change the amount of solar energy it radiates and change its course. However, the amount of paint required could be huge.

Lu and colleagues originally thought about landing a spacecraft on the surface of an asteroid, in order to gently push it off course. But a lack of gravity means the craft would have to attach itself to the surface of the rock and this could prove complicated because the asteroid might be little more than a pile of rubble, Lu explains.

To make matters worse, asteroids often rotate, so pushing on one could simply set it spinning faster, rather than altering its course.

Hands down winner

Lu’s team finally realised that the spacecraft might not need to land at all. Placing a heavy enough object near the asteroid for long enough could produce sufficient gravitational tug to change its orbit.

For a 200-metre-wide asteroid, the spacecraft would need to weigh about 20 tonnes and lurk 50 metres from its target for about a year to change its velocity enough to knock it off course.

"This is hands down the best idea I have seen," says Erik Asphaug, a planetary scientist at the University of California at Santa Cruz. "This will work, but you need to put a large enough spacecraft out there at the right time."

Taking the hit

Such large spacecraft are perfectly feasible, says Lu. In fact, NASA’s multi-billion-dollar Prometheus programme, which was set to explore the outer solar system but which has been delayed, planned to develop just such a vehicle, propelled by nuclear fission.

The strategy crucially relies on our ability to detect an asteroid threat about 20 years in advance. For larger asteroids this is realistic. But Asphaug says many smaller asteroids – less than about 500 metres across – may go unnoticed until only a few years before impact.

Asphaug suggests it may be better to invest in predicting when and where smaller asteroids could strike, than on massive hazard-averting spacecraft. Governments could then prepare to evacuate affected regions. "In many cases it makes more economic sense to just let the thing hit," he says

 

Journal reference: Nature (vol 438, p 177)

 

Source: http://www.newscientistspace.com/article/dn8291

 


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Sunday, November 06, 2005

Google Striking Fear Into Companies

Some excerpts from the article
 
"Wal-Mart, the nation's largest retailer, strikes fear into the hearts of its competitors and suppliers. Makers of goods from diapers to DVD's must cater to its whims. But there is one company that even Wal-Mart eyes warily these days: Google, a seven-year-old business in a seemingly distant industry."
 
"Google, then, may turn out to have a more far-reaching impact than earlier Web winners like Amazon and eBay."
 
"Google, which tends to keep its plans secret, certainly has the wealth to fund ambitious ventures. Its revenues are growing by nearly 100 percent a year, and its profits are rising even faster. Its executives speak of the company's outlook only in broad strokes, but they suggest all but unlimited horizons."
 
"Google represents a challenge to newspapers, to be sure," said Gary B. Pruitt, chief executive of the McClatchy Company, a chain of 12 newspapers including The Star Tribune in Minneapolis and The News & Observer in Raleigh, N.C. "Google is attacking the advertising base of newspapers."
 
"Mr. Breyer, the Wal-Mart board member, watches Google closely in his job as managing partner of Accel Partners, a venture capital firm in Silicon Valley. These days, he advises startups to avoid a "collision course" with Google, just as he has long counseled fledgling companies to steer clear of Microsoft's stronghold in desktop software."
 
Read the entire article here:
 


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