MY EXPIRIENCE WITH WINDOWS 7

Windows 7 : The newest Operating System for PCs from Microsoft Co.

I have had meeting with many people who just not satisfied with Windows 7. They have many problems with it and some of them seemed to be very much annoyed while even talking about Windows 7 because they couldn't even install it to their computer. Some problems they mentioned are as follows:

1. Upgrade hangs at 62% in Vista environment.

Some people was very annoyed with the installation process of Windows 7. They told me each time they tried to install it, It hanged at 62% and after rebooting it got back to Windows Vista again.

Although I never faced this problem and the process was quite fine with me

Howevr if you still facing the problem installing Windows 7 then you should click here to know what to do to fix it up.

2. It faild to find  DVD drive

In some other cases, I found people complaining that Windows 7 couldn't find the DVD drive although it was visible in BIOS.


To fix this problem up...The standard solution here is to run REGEDIT, browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\, then delete both UpperFilters and LowerFilters in the right-hand pane (UpperFilters.bak and LowerFilters.bak entries can be ignored).


No change? Resetting the drive letter has worked for some. Click Start, type Disk Management and choose the "Create and format hard disk partitions" link. If your optical drive is visible here then right-click it, select Change Drive Letter and Paths, click Change and choose a new letter. If the drive is now visible in Explorer, then repeat the process to change the drive letter back; if it's still not visible, reboot and it should appear.



Although as i mentioned earlier many people isn't happy with windows 7,

Is a cosmic chameleon driving galaxies apart?

Where do we look to observe this accelerated expansion? (Image: NASA)


A shape-shifting fifth fundamental force could neatly explain the mystery of dark energy – and some other puzzling astronomical observations




ASK A cosmologist for a potted history of the universe, and it might go something like this: the cosmos began some 13.6 billion years ago with a big bang, exploding from a pinprick of searing heat and incredible density. Since then, it has been cooling and expanding: at first exponentially fast, but soon at a more measured, steady tempo.



At that point our friendly cosmologist might give voice to a little embarrassment. Because if measurements of the distance to faraway supernovae are to be believed, around 5 billion years ago the universe's expansion started to accelerate again. We don't know why. A mysterious "dark energy" permeating space is generally fingered as the culprit. But while this entity apparently flings galaxies apart with gusto, it has never been seen or produced in the lab and seemingly does not interact directly with light or matter on Earth or elsewhere. Such undetectability runs counter to the stuff of science.

Dark energy flings galaxies apart with gusto, but it has never been seen or produced on Earth

Or are we just overlooking evidence that is already there? Some inconsistencies in recent astrophysical observations, easy to dismiss as blips if taken on their own, might invite a startling conclusion when looked at together: that the cosmos is suffused by a fifth force in addition to the canonical four of gravity, electromagnetism and the strong and weak nuclear forces. What is unusual about this force is that its range changes according to its environment - a cosmic chameleon that might just explain the mysteries of dark energy.




The basic idea for this fifth force was hatched in 2004 by Justin Khoury and Amanda Weltman, then members of a team led by well-known string theorist Brian Greene at Columbia University in New York City. String theory is the favoured route to unifying gravity, the odd one out among the four forces, with the other three under the umbrella of quantum mechanics. It is a great playground for devising new fields and forces. The theory is formulated in 11 dimensions, seven of which are assumed to be curled up so small that we cannot see them. Disturbances in those curled-up dimensions might make themselves felt as "extra" forces in the four dimensions of space and time we do see.



For this picture to make sense, the effects in the visible dimensions must match our observations of the universe. Khoury and Weltman proposed one way of doing this: an extra force could be transmitted by particles whose mass depends on the density of the matter around them. That way, its effects could remained veiled on Earth.



How would that work? Well, in quantum mechanics, the range of influence of a force depends largely on the mass of the particles produced by the associated force field: the lighter the particle, the longer the force's range. Electromagnetic fields, for example, produce photons that have no mass whatsoever, so the range of the electromagnetic force is infinite. The particles that transmit the weak nuclear force, on the other hand, are extremely heavy and do not travel very far, confining the force to the tiny scales of the atomic nucleus. With the strong nuclear force, things are slightly more complex: the associated particles, called gluons, are massless but also have the ability to interact with themselves, preventing the force from operating over large distances.



Khoury and Weltman started from the observation that the average density of matter in Earth's vicinity is very high in cosmic terms, at about 0.5 grams per cubic centimetre. Under these circumstances, they proposed, the particle that transmits the chameleon force would be about a billion times lighter than the electron. The force itself would then have a range of not more than a millimetre - small enough for its effects to have remained undetected in the lab so far.



In the wide open spaces of the cosmos, however, where a cubic centimetre contains just 10-29 grams of matter on average, the mass of the chameleon particle plummets by something like 22 orders of magnitude, producing a muscular force that could act over millions of light years. The lost mass is picked up as energy by the chameleon field.



Although the initial motivation was not to find a mechanism to explain dark energy, the idea that the chameleon might do so was always on their minds, says Weltman. With a few tweaks, it did. It could be made to create a kind of negative pressure that, on cosmic scales, would produce a repulsive effect in opposition to gravity. And with its dependence on density, the chameleon force could be made to appear 5 billion years ago, when the density of the expanding cosmos fell below a critical value. The force would propel galaxies away from one another at an ever-increasing rate, producing the kind of accelerated expansion we observe in the wider cosmos, all the while remaining hidden on Earth.

Chlorine study suggests moon is dry after all

The moon's interior may not be that wet after all, despite some recent studies that have suggested otherwise. A new analysis of Apollo rocks backs the old idea of a waterless world.




For decades after the Apollo astronauts touched down on the desolate lunar surface, the moon was considered to be parched. But that view began to change in 2008, when researchers found water inside tiny spheres of lunar volcanic glass at concentrations calculated to be similar to those found in some terrestrial volcanic rocks.



Now, researchers led by Zachary Sharp at the University of New Mexico in Albuquerque say measurements of chlorine in a dozen Apollo samples suggest that the moon's interior has always been extremely dry, containing 10,000 to 100,000 times less water than Earth's.

 

Water-loving element

Chlorine comes in two stable isotopes – 35Cl and 37Cl, which has two more neutrons.



Sharp's team found the heavier version is relatively more abundant in the moon samples than on Earth, suggesting the moon rocks formed in a very dry environment.



That is because hydrogen atoms contained in water readily bond with the heavy chlorine isotope to form hydrocholoric acid gas, which then leaks away into space – leaving more of the lighter isotope behind.



The moon sample measurements suggest that water was present at concentrations of 180 parts per billion in the lunar mantle. That's in line with water concentrations recently measured in a lunar mineral called apatite by Francis McCubbin of the Carnegie Institution of Washington in Washington DC. "These water contents [are] very dry in comparison to Earth and Mars," he says, suggesting that previous studies that argued for Earth-like water concentrations "are likely extrapolating their data a bit too far".



What's the norm?

Those studies may have based their conclusions on very unusual lunar samples, Sharp says. He says the moon may have formed with very little water – and that no additional water from comets is necessary to explain the suite of current observations.



The moon is thought to have formed from the shrapnel of a collision between a Mars-sized object and the infant Earth 4.5 billion years ago. As the initially molten moon crystallised into rock, Sharp says minute amounts of water would have become more and more concentrated in ever-shrinking amounts of liquid magma.



This water-rich magma eventually would have erupted onto the surface because it was rich in volatiles, and the Apollo astronauts may have collected it in the form of the volcanic glass beads. "Whether these volatile-rich magmas or glasses are representative of the moon or not – that's the question," Sharp told New Scientist.



'Blind men and the elephant'

It's too soon to settle that question, says James Greenwood of Wesleyan University in Middletown, Connecticut, whose own isotopic studies of lunar apatite suggest that comets delivered water to the early moon. He says different regions of the moon may have different amounts of water because the roiling magma ocean that enveloped the early moon may have solidified before water from impacting comets got mixed through it evenly.



"I think what we're really doing is the case of the three blind men and the elephant – they've looked at samples and that's what they find, and we find what we find," he told New Scientist.



McCubbin says studying more samples, particularly those collected from areas not yet explored by Apollo or robotic missions, will be key to piecing together the history of lunar water. Water can change the force needed to bend or break rocks, and affect what minerals are formed when magma crystallises, he says: "The question of a wet or dry moon matters because water plays such an important role in geologic processes."



Journal reference: Sciencexpress (DOI: 10.1126/science.1192606)

Innovation: Re-inventing urban wind power again

Innovation is our regular column highlighting emerging technologies and predicting where they may lead




With the environmental movement gathering momentum, many are thinking of installing wind turbines to generate their own electricity. Unfortunately, wind speeds in urban areas are usually too slow and turbulent to make micro wind generation cost-effective.



So while the strict planning regulations that have prevented homeowners from erecting domestic turbines in the UK are expected to be relaxed next month, city-dwellers may find manufacturers reluctant to sell them their turbines for fear that poor performance will reflect badly on a young and vulnerable industry.



However, researchers at Cornell University in Ithaca, New York, believe that the problem is not with the low wind speeds after all, but with the methods used to harvest wind power. Cities have plenty of wind energy we can use, they say, but to harness it requires a different tack. It's time to reinvent the urban wind turbine.



Moving away from traditional electromagnetic generators and turbines may seem like a radical step, but on a small scale and with low wind speeds, piezoelectric generation looks like an attractive option.



Ephrahim Garcia, a mechanical engineer at Cornell, attached a flexible aerofoil to the end of a pole made out of a piezoelectric material. When air passes over the aerofoil it flutters, causing the pole to flex and generate a small alternating current. "The inspiration came from fish tails," Garcia says.



Garcia and colleague Matthew Bryant tested aerofoils that were 13 centimetres long in a wind tunnel, and found that they generated power in the milliwatt range from wind speeds of just 2 metres per second. With many devices operating in parallel, the amount of power generated could quickly add up, they say.



Leaf out of nature's book

Hod Lipson, also at Cornell, and Shuguang Li, now at the Northwestern Polytechnical University in Xi'an, China, have been working on the same principle. Taking a leaf out of nature's book, they have devised a tree-like configuration that uses lots of flapping leaves as generators.



The leaves are attached to vertically hanging piezoelectric branches by a hinge. As air flows over the leaves, instabilities create turbulent vortices first on one side and then on the other, causing it to flap.



To make the technology as cost-effective as possible, Lipson and Li built their branches from a piezoelectric material called polyvinylidene fluoride, or PVDF. However, while this is cheap it is relatively insensitive, "so we had to find ways to make it shake more vigorously", says Lipson. For this reason the leaves are designed to twist as well as bend the branch, increasing the strain acting on it.



Each leaf can generate nearly 0.3 milliwatts of power, the team say. Although considerably less than Garcia's arrangement, at just a few centimetres long they are smaller and potentially cheaper, says Lipson.



Another solution is to increase the wind speed. Borrowing a trick from the world of concentrated solar power, Kevin Pratt and Francis Charles Moon, both at Cornell, have designed honeycomb-like arrays of funnels designed to accelerate wind as it passes over fluttering piezoelectric strips just a few centimetres across.



Like a lens

"The amount of energy contained within moving wind is determined by the amount of air and its speed," says Pratt. So by forcing the same volume of air through a smaller aperture you can increase the speed. "It's the wind equivalent of a lens," he says.



Computer simulations have shown that some concentrator designs should be able to increase the wind speed by more than 50 per cent. The pair are now building the first prototype for wind tunnel tests. They envisage the final product containing arrays of 30-centimetre-wide concentrators, each housing several dozen piezoelectric strips.



Wind concentrators are not a new idea, but have proved impractical for standard turbines because of their large size. By shrinking the technology the researchers hope to achieve an output power of 5 watts per square metre, roughly one-third of that created by solar power. So if they can be made for a third of the price of solar panels, then the technology could be competitive.



Journal references: Garcia and Bryant's work is published in the Proceedings of SPIE, DOI: 10.1117/12.815785; Lipson and Li's work is published in the Proceedings of the ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems