Thursday, 11 November 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Legs Apart Under Laptop: Your Sperm Will Thank You

Posted: 10 Nov 2010 12:05 PM PST

If guys can find a way to operate laptop computers with their legs apart, they might limit their risk of infertility, a new study finds. Keeping the legs splayed while using a laptop generated substantially less damaging heat in the scrotum than keeping legs together, scientists report online Nov. 8 in Fertility and Sterility. Putting a shield under the laptop didn't seem to help beat the heat.

A hot scrotum is no laughing matter. The testes generally are 2 to 4 degrees Celsius cooler than standard body temperature, a unique environment conducive to the rapidly dividing nature of sperm cells. Heating the area can trigger oxidative stress, slow the motion of sperm and lessen their ability to fertilize an egg for weeks or months, says Edmund Sabanegh, a urologist at the Cleveland Clinic in Ohio.

In the new study, urologist Yefim Sheynkin of Stony Brook University in New York and his colleagues enlisted 29 men ages 21 to 35 to participate in three tests in which each man operated a laptop computer on his thighs for one hour. One test entailed keeping the thighs together while using the machine. A second required the same position, but with a padded shield placed under the laptop. The third test allowed the men to keep their legs apart at a 70-degree angle as they used a laptop with a shield supporting it that was wide enough to reach across both legs and stabilize the computer.

Each of the men completed all three tests, but did only one test per day. Before each experiment, sensors recorded the scrotum temperature of each volunteer and recorded any changes during the session.


All three uses of a laptop increased the men's scrotal temperature substantially from pretest levels, but keeping the legs splayed limited this increase to about 1.4 degrees Celsius during the hour-long test. When the legs were kept together the temperature rose by 2.2 degrees with a shield and 2.3 degrees without one.

What's more, it took an average of 28 minutes for scrotal temperatures to rise 1 degree Celsius when the men had their legs apart, but only 14 minutes to increase that much when they kept their legs together with a shield and 11 minutes with legs together and no shield.

"Having the legs together, which is how most people use laptops, does seem to be the worst," Sabanegh says. "This makes a lot of sense."

The laptop shields — also called laptop pads or trays — are sold online and in office-supply stores, though not typically as protective devices, says Sheynkin. He recommends that men put laptops on desks or tables, which enables them to move their legs around and avoid being trapped in a single position for extended periods.

Sabanegh says that many men have come to understand the risks of increasing the scrotum temperature. While such heat may not always be the underlying problem for a couple with fertility issues, it's part of counseling. "I tell them, 'Try to be healthy in all the ways you can.' And that means stop putting laptops on your lap, stop using hot tubs and other things of that nature."

Image: Flickr/IITA Image Library

China Releases Images of Proposed Lunar Landing Site

Posted: 10 Nov 2010 11:32 AM PST

The first images from China's Chang'e-2 lunar probe were released Nov. 8.

The photos show a lunar lava plain called Sinus Iridium (Bay of Rainbows), a proposed destination for China's first lunar rover in 2013. China also has plans to bring lunar rocks back to Earth in 2017.

Chang'e-2 launched Oct. 1 and entered an orbit 62 miles above the lunar surface Oct. 9. To take the pictures, the orbiter swooped to an altitude of just 9 miles. The photos have 100-times-higher resolution than those taken by the orbiter's predecessor, Chang'e-1, in 2007.

"The relaying back of the pictures shows that the Chang'e-2 mission is a success," said Zhang Jiahao, director of the lunar exploration center under the China National Space Administration, in a press release.


Images: China National Space Administration

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Enough Oxygen for Life Found Millions of Years Too Early

Posted: 10 Nov 2010 10:37 AM PST

Earth's atmosphere contained enough oxygen for complex life to develop nearly 1.2 billion years ago — 400 million years earlier than scientists previously believed.

The findings, reported in the Nov. 11 Nature, could lead scientists to reconsider the prerequisites for animal life, on Earth and other planets.

"It means that the conditions were in place for complex life to arise," said geologist John Parnell of the University of Aberdeen in Scotland, lead author of the new study. "There might be animals in that earlier window that we have not yet found."

Geological records show there was one major increase in the amount of oxygen in Earth's atmosphere around 2.3 billion years ago, and another around 800 million years ago.

That second spike in oxygen levels was thought to be connected to the Cambrian explosion, the swift development of most of the major animal groups that came around 550 million years ago.

Parnell's results suggest oxygen can't be the whole story.

"It may have been that something else gave evolution the kick-start which caused animals to evolve," he said. "Oxygen in the atmosphere was already there for quite a long time."


To figure out how much oxygen was in the early atmosphere, Parnell and his colleagues searched 1.2 billion-year-old rocks from what was once a lakebed in Scotland for the chemical signatures of ancient bacteria.

Before there was a useful amount of free oxygen around, these bacteria used to get energy by converting sulfate, a molecule with one sulfur atom and four oxygens, to sulfide, a sulfur atom that is missing two electrons.

Geologists can get a glimpse of how efficient the bacteria were by looking at two different sulfur isotopes, versions of the same element that have different atomic masses. Converting sulfate to sulfide leaves the rock with a lot more of the isotope sulfur-32 than would be there without the bacteria's help.

The geologists extracted pyrite, also known as fool's gold, from the rocks. They then pulled sulfur from the pyrite by chemical processing and by zapping the rocks with a laser. The amount of sulfur-32 was much higher than bacteria could have produced without oxygen.

Parnell suggests the bacteria were able to use oxygen in the atmosphere to convert between the two different forms of sulfur (sulfate and sulfide) many times.

"Their metabolism was becoming more complicated," he said. "The more cycles of that [reaction] that they caused, the more sulfur-32 you ended up with."

The team concluded that the amount of oxygen in the atmosphere 1.2 billion years ago approached the levels at the time of the Cambrian explosion, roughly 10 percent of current oxygen levels. Ten percent may be enough to start complex life, Parnell says.

"It's only when you can start processing oxygen in a complex way that you can then start to produce different cells that do different things," Parnell said. "That's what gives rise to animals."

The evolution of large animals could have been triggered by changing geological conditions, like the end of a dramatic ice age about 600 million years ago, he says.

Parnell also hinted that the results could have implications for sulfur-eating bacteria on other planets like Mars, although because he has another paper in preparation, he didn't want to go into very much detail.

"If there are microbes on Mars either today or in the past, this kind of metabolism is one which would be readily available to them," he said. "The stage of chemical reduction from sulfate to sulfide is completely feasible on Mars."

"I'm pretty thrilled by the paper," said geochemist Michael Russell of NASA's Jet Propulsion Lab, who was not involved in the new study. "I'd like to see this kind of thing done ever further back in time, so we can get a sense of just how much oxygen there was in the atmosphere."

Image: 1) The cave near Lochinver in the north-west Highlands of Scotland where Parnell and his colleagues collected sulfur-rich rocks. 2) Slivers of fool's gold that hold clues to Earth's early atmosphere. Credit: Stephen Bowden, University of Aberdeen

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New Sharp Image of Violent Galactic Collision

Posted: 10 Nov 2010 09:02 AM PST

Two galaxies collide head-on in this new image from the European Southern Observatory.

The resulting maelstrom of stars is called the Atoms-for-Peace galaxy (more formally NGC 7252 or Arp 226) after a speech about nuclear power President Eisenhower gave in December 1953. But this tumultuous galactic merger is anything but peaceful. The pair of galaxies are tearing each other apart, sending swoops and streams of stars, gas and dust flying into nearby space.

This image also captures shells that formed as gas and stars were ripped from the colliding galaxies and wrapped around their joint core. Some of this material was compressed, sparking bursts of star formation.


Our own Milky Way galaxy is headed for a similar fate in the next 3 billion or 4 billion years. We're on a collision course with the nearby Andromeda Galaxy.

Atoms-for-Peace lies about 220 million light-years away in the constellation Aquarius, and is bright enough to be seen through a backyard telescope, though it appears as a small fuzzy blob. This image was taken with ESO's Wide Field Imager at the La Silla Observatory in Chile.

Image: ESO

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All Life on Earth Could Have Come From Alien Zombies

Posted: 10 Nov 2010 04:00 AM PST

Life on Earth could have grown from the broken remains of alien viruses that, although dead, still contained enough information to give rise to new life.

Scientists have speculated that life could have come to Earth from space — a notion called panspermia — since the 1870s, when Lord Kelvin suggested microbes could have ridden here on a comet or meteor. Others have suggested tiny organisms could cross the galaxy embedded in dust grains, which could be nudged from one planetary system to another by the slight pressure of stars' radiation.

However, most astrobiologists think that same radiation spells a death sentence for delicate microbes.

"That essentially kills panspermia in the classical sense," said astrobiologist Rocco Mancinelli of the SETI Institute in Mountain View, California.

But maybe not, says astronomer Paul Wesson, a visiting researcher at the Herzberg Institute of Astrophysics in Canada. In an upcoming paper in Space Science Reviews, Wesson argues that even if the actual microbes are dead on arrival, the information they carry could allow life to rise from the charred remains, an idea he calls necropanspermia.

"The vast majority of organisms reach a new home in the Milky Way in a technically dead state," Wesson wrote. "Resurrection may, however, be possible."


The key lies in how much genetic information survives the trip, Wesson says. An organism's genetic information is encoded in the sequence of nucleotides in their DNA. This information can be measured in bits in the same way as computer processes. Bacteria like E. coli, for example, carry about 6 million bits of information in their DNA.

Random chemical processes couldn't produce enough information to run even a simple cell. Over 500 million years, random molecular shuffling would produce only 194 bits of information, Wesson says.

One possible way around this paradox is the idea that life on Earth was seeded by biological molecules that already had a large information content that survived the journey even though the molecules themselves were killed.

Wesson is a bit fuzzy on how that information would translate to new, healthy living things.

"It must be admitted that all versions of panspermia suffer from a hole in our knowledge, concerning how to go from an astrophysically delivered entity which contains substantial information to one which has the characteristics of what we normally regard as life," he wrote.

But he does pinpoint the virus as a good candidate for the vessel that carried all that information. Viruses are basically strands of genetic material encased in a coat of proteins and sometimes fats. They carry about 100,000 bits of information, and may have evolved independently from conventional cells. Suggestively, viruses seem to assemble themselves from particles of protein, without needing assistance from other molecules or specific genetic information.

The paper "looks good, and interesting, although of course highly speculative," David Morrison, the director of the Carl Sagan Center for the Study of Life in the Universe, wrote in an e-mail. "The critical issue is whether the information in broken strands of nucleic acid could serve as the template for life on another world … since we know so little about the actual process by which life originated on Earth, who can really say?"

But Mancinelli, who was not involved in the new study, doesn't buy it.

"Once you're dead, you're dead," he said.

The paper neglected two other things that could kill cells or viruses on their way through the galaxy, Mancinelli added. Elements like potassium can decay over the millions of years it takes to cross the galaxy, adding extra damage even if the organisms are shielded from space radiation

"It'll give off enough radiation that it'll just chop up all the nucleic acids," he said. "There's no way the organism will survive."

The other issue is that, especially in a vacuum, hydrogen and hydroxyl molecules get ripped off cells and combine to form water. This process, called dessication, "is more than just drying up," Mancinelli said. "You denature proteins. You rip them apart, recombine them, and they no longer have any functionality. That can happen even if you're in a rock."

Life would have a better chance if it didn't have so far to travel, he added.

"Going from Earth to Mars, not a problem," he said. "Even going from Earth to Pluto, or from Pluto to Earth, not a problem. But once you start heading out of the solar system, it's so far away that it takes a long time. That's the thing, the length of time."

Image: A transmission electron micrograph image of the influenza virus. Flickr/kat m research

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