Tuesday, April 29, 2008

Northern Lights Glimmer With Unexpected Trait

An international team of scientists has detected that some of the glow of Earth’s aurora is polarized, an unexpected state for such emissions. Measurements of this newfound polarization in the Northern Lights may provide scientists with fresh insights into the composition of Earth’s upper atmosphere, the configuration of its magnetic field, and the energies of particles from the Sun, the researchers say.

If observed on other planets, the phenomenon might also give clues to the shape of the Sun’s magnetic field as it curls around other bodies in the solar system.

At the north and south magnetic poles, many charged particles in the solar wind —a flow of electrically charged matter from the Sun—are captured by the planet’s field and forced to plunge into the atmosphere. The particles strike atmospheric gases, causing light emissions.

Lilensten and his colleagues observed weak polarization of a red glow that radiates at an altitude of 220 kilometers. The glow results from electrons hitting oxygen atoms. The scientists had suspected that such light might be polarized because Earth’s magnetic field at high latitudes funnels the electrons, aligning the angles at which they penetrate the atmosphere.

Fluctuations in the polarization measurements can reveal the energy of the particles coming from the Sun when they enter Earth’s atmosphere, Lilensten notes. The intensity of the polarization gives clues to the composition of the upper atmosphere, particularly with regard to atomic oxygen. link
Ref: Polarization in aurorae: A new dimension for space environments studies. 2008. Jean Lilensten et al. GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L08804

Thursday, April 17, 2008

Mysterious Striped Currents In Our Oceans

Between 1992 and 2003, scientists collected data from more than 10,000 drifting ocean buoys, which they tracked with satellites. The buoys’ movements were influenced mainly by known global currents, which are driven by wind and by differences in the temperature and salinity of seawater.

SubHuman © M. Ryan & M Schultz
But it emerged that something else had been subtly influencing the buoys’ paths. It turned out that there were alternating strips of water running eastward or westward, a bit like parallel moving sidewalks. Niiler recalls his reaction: “My God, we’ve never seen these before.”

Satellite measurements showed that the interfaces between adjacent currents were alternately associated with slight peaks and troughs in sea level. When the team looked at this variation globally, they found that the 150-kilometre-wide bands covered pretty much every ocean.

They recorded currents flowing in opposite directions at around 40 metres per hour. The flows extend right down to the ocean floor, and the boundaries between currents are alternately associated with peaks and troughs in temperature as well as sea level. This suggests that they influence processes such as nutrient and energy flow around the oceans, but this has yet to be proven, says Niiler.

What causes the striped flows remains a puzzle. “They are a fascinating new aspect to the ocean’s circulation, but the jury is still out on the mechanisms leading to their formation,” says Geoff Vallis of the Geophysical Fluid Dynamics Laboratory at Princeton University.

He points out that similar patterns exist in atmospheric flows on other planets, for example, Jupiter. Whether similar effects are at play here is unclear, he says. link
Ref: Maximenko, N. A., O. V. Melnichenko, P. P. Niiler, and H. Sasaki (2008), Stationary mesoscale jet-like features in the ocean. Geophys. Res. Lett., in press.

Saturday, April 12, 2008

This Day In History: Nerve Gas Outbreak

In 1968, a sudden outbreak of startling sheep deaths in Skull Valley, Utah, was attributed to a nerve gas sprayed earlier by the Army on the nearby Dugway Proving Grounds. The investigation made by the National Communicable Disease Center was hampered by the Army's initial denial of responsibility and slowness to provide adequate gas samples for independent agencies to check. The debacle led to an overhaul of procedures concerning development of chemical weapons at Dugway. link.

Contamination” trailer – music by Goblin:

Wednesday, April 9, 2008

Before The Big Bang

Until very recently, asking what happened at or before the Big Bang was considered by physicists to be a religious question. General relativity theory just doesn’t go there – at T=0, it spews out zeros, infinities, and errors – and so the question didn’t make sense from a scientific view.
But in the past few years, a new theory called Loop Quantum Gravity (LQG) has emerged. The theory suggests the possibility of a “quantum bounce,” where our universe stems from the collapse of a previous universe. Yet what that previous universe looked like was still beyond answering.

Physicists have now developed a simplified LQG model that gives an intriguing answer: a pre-Big Bang universe might have looked a lot like ours.

“The significance of this concept is that it answers what happened to the universe before the Big Bang,” Singh told PhysOrg.com. Our study shows that the universe on the other side is very classical as ours.”

“This means that the twin universe will have the same laws of physics and, in particular, the same notion of time as in ours,” Singh said. “The laws of physics will not change because the evolution is always unitary, which is the nicest way a quantum system can evolve. In our analogy, it will look identical to its twin when seen from afar; one could not distinguish them.”

That means that our universe today, roughly 13.7 billion years after the bounce, would share many of the same properties of the pre-bounce universe at 13.7 billion years before the bounce. In a sense, our universe has a mirror image of itself, with the Big Bang (or bounce) as the line of symmetry.

Ultimately, Corichi and Singh’s model might even tell us what a future universe would look like. Depending on how fast our present universe is accelerating – which will ultimately determine its fate – there’s a possibility that a generalization of the model would predict a re-collapse of our own universe.

Ref.: Quantum bounce and cosmic recall. 2008. Corichi, Alejandro, and Singh, Parampreet. In press, Physical Review Letters.

Saturday, April 5, 2008

Oldest Human Coprolite Found

Human mitochondrial DNA from dried excrement recovered from Oregon's Paisley Caves is the oldest found yet in the New World -- dating to 14,300 years ago, some 1,200 years before Clovis culture.
The Paisley Caves are located in the Summer Lake basin near Paisley, about 220 miles southeast of Eugene on the eastern side of the Cascade Range. The series of eight caves are wave-cut shelters on the highest shoreline of pluvial Lake Chewaucan, which rose and fell in periods of greater precipitation during the Pleistocene.

Clovis culture began sometime between 13,200 and 12,900 years ago. Skeletal remains dating to Clovis culture have proven elusive, leaving researchers with little hard evidence beyond tell-tale cultural components such as the distinctive fluted Clovis points and other tools.

Exactly who these people living in the Oregon caves were is not known. At this point, we know they most likely came from Siberia or Eastern Asia, and we know something about what they were eating, which is something we can learn from coprolites. We're talking about human signature.

“Had the human coprolites at the Paisley Caves not been analyzed for DNA and subjected to rigorous dating methodology,” he added, "the pre-Clovis age of the artifacts recovered with the megafaunal remains could not have been conclusively proven. In other words, the pre-Clovis-aged component of this site could very well have been missed or dismissed by archaeologists.” link
Ref: DNA from Pre-Clovis Human Coprolites in Oregon, North America. 2008. M. T. P. Gilbert et al. Science, published on-line April 3.

Thursday, April 3, 2008

Is DNA Repair a Substitute For Sex?

Bdelloid rotifers seem to get along just fine without sex. What’s more, they have done so over millions of years of evolution, resulting in at least 370 species. These hardy creatures somehow escape the usual drawback of asexuality – extinction!

Bdelloid rotifers have been able to give up sex and survive because they have evolved an extraordinary efficient mechanism for repairing harmful mutations to their DNA.

In animals that do have sex, DNA repair is accomplished during meiosis, when chromosomes pair up (one from the father, one from the mother) and “fit” genes on one chromosome can serve as templates to repair damaged genes on the other chromosome. The bdelloid, though, always seems to reproduce asexually, by making a clone of itself. How then, does it cope with deleterious mutations?

Scientists demonstrated the enormous DNA repair capacity of bdelloid rotifers by zapping them with ionizing radiation (gamma rays), which has the effect of shattering its DNA into many pieces. “We kept exposing them to more and more radiation, and they didn’t die and they didn’t die and they didn’t die,” says Mark Welch. Even at five times the levels of radiation that all other animals are known to endure, the bdelloids were able to continue reproducing.

Philodina roseola
The bdelloids’ DNA repair capacity probably evolved due to a different environmental adaptation – tolerance of extreme dryness. Bdelloids, which live in ephemeral aquatic habitats such as temporary freshwater pools and on mosses, are able to survive complete desiccation (drying out) at any stage of their life cycle. They just curl up and go dormant for weeks, months, or years, and when water becomes available, they spring back to life. Desiccation, like ionizing radiation, breaks up the rotifers’ DNA into many pieces. Presumably, the same mechanisms they use to survive desiccation as part of their life cycle also protect them from ionizing radiation.

Extreme Resistance of Bdelloid Rotifers to Ionizing Radiation.2008. Gladyshev, E., and M. Meselson . Proc. Natl. Acad. Sci. 105 (13): 5139-5144.

Evidence for degenerate tetraploidy in bdelloid rotifers. 2008. Mark Welch, D.B., J.L. Mark Welch and M. Meselson. Proc. Natl. Acad. Sci. 105 (13): 5145-5149.

Wednesday, April 2, 2008

Died This Day: Hermann Rorschach

Watchmen & Rorschach © DC Comics
Rorschach (Nov. 8, 1884 - April 2, 1922) was a Swiss psychiatrist who devised the inkblot test that bears his name and that is widely used clinically for diagnosing psychopathology. His secondary-school nickname was Kleck, meaning "inkblot," because of his interest in sketching.

In 1917, he learned of Szyman Hens, who had studied the fantasies of his subjects using inkblot cards. Rorschach began in 1918 using 15 accidental inkblots, asking patients, "What might this be?" He knew the human tendency to project interpretations and feelings onto ambiguous stimuli. The subjective responses of his subjects enabled him to distinguish among them on the basis of their perceptive abilities, intelligence, and emotional characteristics. His published results (1921) drew little interest until after his death. link

Tuesday, April 1, 2008

Jack Kirby Explains The Origin of Mankind

The Eternals created by Jack Kirby & © Marvel Comics
Jack Kirby retold the origin of the Earth and the evolution of Mankind more than once in his career as he introduced his wild new concepts to the comic book reading world. Here’s his take from ‘The Eternals’:


Jack explains what it's all about:

Read it all in the next issue of, "THE ETERNALS!"

Read Jack's "Origin of Homo mermanus"