Mitochondria are tiny capsule-shaped structures that produce energy for the cell. Each cell has dozens to hundreds of mitochondria, and each mitochondrion contains several copies of circular strands of DNA. This DNA is distinct from the main genome in the cell's nucleus, which is inherited from both the mother and father. Mitochondria, in contrast, are passed directly from a mother's egg cell to her offspring. Until recently, most scientists believed that nearly all of a person's cells contain identical copies of mtDNA inherited from the mother. A new approach for analyzing DNA shows that each person's mitochondrial DNA (mtDNA) is surprisingly variable in different body tissues. The finding may eventually prove useful for spotting and monitoring cancer, as it leads to telltale mtDNA variations that can be detected in the bloodstream.

A research team led by Drs. Nickolas Papadopoulos and Bert Vogelstein of Johns Hopkins University used new, highly sensitive DNA sequencing technologies to take a closer look at mtDNA variability in different tissues within several individuals. The research was supported by NIH's National Cancer Institute (NCI) and the Howard Hughes Medical Institute. The researchers described a series of mtDNA analyses, including a detailed evaluation of 10 different tissues taken from a single person. Although most analyzed mtDNA was identical, the researchers detected at least 1 variant form of mtDNA in each tissue, and 4 tissues harbored at least 4 variants. The proportion of variant mtDNA in tissues differed widely. In some cases, certain tissues - like kidney and liver - shared a variant that wasn't found in other tissues.The technique can detect relatively rare single-letter variants in stretches of DNA - even those found in as few as 1 in 10,000 mitochondrial genomes.

How did life on Earth begin? One hypothesis is that terrestrial life began when organics were delivered from outer space during the early, heavy bombardment phase of Earth's development. We know that several meteorites (e.g., Murchison) have amino acids with properties similar to those seen in biological amino acids, the building blocks of life.

An international team of astronomers led by Fukue and Tamura of the National Astronomical Observatory of Japan conducted research on the properties of light in a massive star-forming region (BN/KL nebula) of the Orion Nebula and have investigated a process that may have played a role in the development of life on Earth.

The origin of what is technically called "biomolecular homochirality" is a longstanding mystery and an important one to solve, since it characterizes most life forms on Earth.

"Superbright Venus popped out of the twilight first, followed minutes later by Mars and Saturn," says De Rosa. "The sight of the lovely celestial triangle over the calm water of the lake was really great!"

The three planets will remain in triangular formation for many nights to come, only the angles will change. Keep an eye on the sunset! Sky maps: August 1, 2, 3, 4, 5, 6, 7, 8.

More triangle images: from Amirreza Kamkar of Qayen, Khorasan, Iran; from Gary A. Becker of Coopersburg, PA; from Stefano De Rosa of Viverone lake, Turin, Italy; from Richard Glenn of Gold Beach, Oregon; from Adrian New of San Antonio, Texas.

An ultra-strong glass that has been looking for a purpose since its invention in 1962 is poised to become a multibillion-dollar bonanza for Corning Inc.

The 159-year-old glass pioneer is ramping up production of what it calls Gorilla glass, expecting it to be the hot new face of touch-screen tablets and high-end TVs.

Gorilla showed early promise in the '60s, but failed to find a commercial use, so it's been biding its time in a hilltop research lab for almost a half-century. It picked up its first customer in 2008 and has quickly become a $170 million a year business as a protective layer over the screens of 40 million-plus cell phones and other mobile devices.

Now, the latest trend in TVs could catapult it to a billion-dollar business: Frameless flat-screens that could be mistaken for chic glass artwork on a living-room wall.

A settlement dating back about 7,000 years has been discovered by a hill near the village of Ivanovo, in Shoumen municipality, in eastern Bulgaria, Bulgarian National Television (BNT) reported on July 26 2010.

The settlement, 900 square miles in area, lies between two rivers on the south face of the hill. In spite of its natural defenses, the settlement was fortified with a defensive wall of "unusual shape", BNT said.

"The shape of the fortification was not circular or oval-like, which was typical for the time but an irregular pattern resembling an octagon," archaeologist Svetlana Venelinova said in a television interview for BNT.

Additionally, the entire settlement was encircled by a moat outside the fortification.

A stone effigy monument, in the shape of a Blackfoot creator god named Napi, has been discovered in southern Alberta - south of the Red Deer River near the hamlet of Finnegan.

One day Old Man determined that he would make a woman and a child; so he formed them both - the woman and the child, her son - of clay. After he had moulded the clay in human shape, he said to the clay, "You must be people" ...

They walked down to the river with their Maker, and then he told them that his name was Na'pi, - Old Man.

From Blackfoot Lodge Tales, George Grinnell, 1892.

The Blackfoot are a people that have inhabited the prairies since ancient times. The effigy dates to somewhere between AD 1000 and AD 1500. It would have been constructed before the time of European contact.

Napi is a deity credited with creating the Blackfoot people and the landscape they inhabit. "According to Blackfoot tradition he's like the creator," said archaeologist Meaghan Porter, who investigated the site.

She said that the image is "made out of rocks and it's in the outline of a man - it has arms and a torso, head and legs as well as genitalia." It's roughly five meters by five meters long. The rocks are about the size of a fist, they have a mix of black, grey and tan colours. Porter doesn't think these colours were chosen deliberately "I think that's just the rocks that were available," she said.

Professor John Burland has spent the last two decades striving to save - and understand - the Leaning Tower of Pisa. After defying gravity, Italian bureaucracy and accusations of corruption, it seems he's finally cracked the case.

All six donkeys were impeccably behaved. They'd been ridden into Pisa's main square, the Piazza dei Miracoli, last November by vexed vets from Pisa University and ceremoniously set down beneath its Leaning Tower. In protest at government cuts across Italian education, the profs duly gave an al fresco lecture on donkey anatomy to hundreds of bewildered tourists. Silvio Berlusconi's photo appeared on many a banner, beside the words 'The biggest ass of all'.

Such a display of faculty dissent would have been impossible a decade ago, when the area of piazza around the tower was completely cordoned off. It looked then more building site than World Heritage site and the howls of protest from local Pisans were far louder than a few braying donkeys.

From 1990 to 2001, the tower remained closed - many doubting it would ever reopen - as the International Committee for the Safeguard of the Leaning Tower strove to save it from collapse. Visitors to Pisa dropped off by 45 per cent.

'The street vendors were furious about lost trade and demanded the tower be reopened,' says John Burland, the only Brit on the 14-man committee. 'But it was close to toppling over. Without our intervention, any local storm or earth tremor could have finished it off.' Burland, 72, is emeritus professor of soil engineering at Imperial College London, his reverend-like humility belying the fact that he helped solve one of the most fascinating riddles in architectural history.

A puzzling pattern in the cosmic rays bombarding Earth from space has been discovered by an experiment buried deep under the ice of Antarctica.

Cosmic rays are highly energetic particles streaming in from space that are thought to originate in the distant remnants of dead stars.

But it turns out these particles are not arriving uniformly from all directions. The new study detected an overabundance of cosmic rays coming from one part of the sky, and a lack of cosmic rays coming from another.

This odd pattern was detected by the IceCube Neutrino Observatory, an experiment still under construction that is actually intended to detect other exotic particles called neutrinos. In fact, scientists have gone out of their way to try to block out all signals from cosmic rays in order to search for the highly elusive neutrinos, which are much harder to find.

A new cosmology successfully explains the accelerating expansion of the universe without dark energy; but only if the universe has no beginning and no end.

As one of the few astrophysical events that most people are familiar with, the Big Bang has a special place in our culture. And while there is scientific consensus that it is the best explanation for the origin of the Universe, the debate is far from closed. However, it's hard to find alternative models of the Universe without a beginning that are genuinely compelling.

That could change now with the fascinating work of Wun-Yi Shu at the National Tsing Hua University in Taiwan. Shu has developed an innovative new description of the Universe in which the roles of time space and mass are related in new kind of relativity.

Shu's idea is that time and space are not independent entities but can be converted back and forth between each other. In his formulation of the geometry of spacetime, the speed of light is simply the conversion factor between the two. Similarly, mass and length are interchangeable in a relationship in which the conversion factor depends on both the gravitational constant G and the speed of light, neither of which need be constant.

So as the Universe expands, mass and time are converted to length and space and vice versa as it contracts.

Bioengineered humans are people who have been biologically upgraded through machine implants, genetic manipulation and drugs. Together, they herald what is popularly known as the coming post-human or Human 2.0 era. Augmentation is any bodily intervention that enhances human function and was not initiated because of a pathological deficiency. The only area where elective augmentation is obvious in everyday life is in cosmetic surgery such as veneers and drugs that enhance human capability and endurance like Viagra.

Biomimicry and bio-enhancement are becoming far more sophisticated. Scientists can now grow new organs in the lab, for example, and 3D bioprinters where they can be printed are being developed by companies like Organovo. However, the incentive to augment the physical strength of the human body is something that most of us don't care about deeply on a daily basis. "I don't need to run faster. I have a car," said a friend when we proposed the advantages of having a robotic foot. Running faster, X-ray vision, hearing at frequencies that only wolves and dogs can hear, having photogenic memory: all this sounds good but none of us would spend the time or money to acquire them because the advantages are not immediately clear. Unlike plastic surgery, which makes us immediately more attractive to the opposite sex, it is unclear what a new kidney would afford me if my current one functions reasonably well.

Of course, there are a number of reasons why we would want to invest in bio-enhancements, such as living longer with loved ones and eliminating susceptibility to malaria in Africa. But the private sector will not pay for the high cost of research based on these lofty goals and the government is already crumbling under debt and budget constraints. Human 2.0 would likely be a pipe dream if it wasn't for one group which is always looking for a superior human: the army.