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January 15, 2007, 5:20 AM CT

Hofmeyr-Skull supports the "Out of Africa"-Theory

Hofmeyr-Skull supports the
Reliably dated fossils are critical to understanding the course of human evolution. A human skull discovered over fifty years ago near the town of Hofmeyr, in the Eastern Cape Province of South Africa, is one such fossil. A study by an international team of scientists led by Frederick Grine of the Departments of Anthropology and Anatomical Sciences at Stony Brook University in New York published recently in Science magazine has dated the skull to 36,000 years ago. This skull provides critical corroboration of genetic evidence indicating that modern humans originated in sub-Saharan Africa and migrated about this time to colonize the Old World. (Science January 12, 2007).

"The Hofmeyr skull gives us the first insights into the morphology of such a sub-Saharan African population, which means the most recent common ancestor of all of us - wherever we come from," said Grine.

Although the skull was found over half a century ago, its significance became apparent only recently. A new approach to dating developed by Grine team member Richard Bailey and his colleagues at Oxford University allowed them to determined its age at just over 36,000 years ago by measuring the amount of radiation that had been absorbed by sand grains that filled the inside of the skull's braincase. At this age, the skull fills a significant void in the human fossil record of sub-Saharan Africa from the period between about 70,000 and 15,000 years ago. During this critical period, the archaeological tradition known as the Later Stone Age, with its sophisticated stone and bone tools and artwork appears in sub-Saharan Africa, and anatomically modern people appear for the first time in Europe and western Asia with the equally complex Upper Paleolithic archeological tradition.........

Posted by: Nora      Read more         Source

January 11, 2007, 6:33 PM CT

Greetings From The Bottom Of The World

Greetings From The Bottom Of The World A team from a previous expedition sets up camp in Antarctica. Credit: NASA
In May 2003, astronaut Don Pettit returned home from his five-month stay aboard the International Space Station. Living in isolated conditions in an extreme environment, he spent much of his time conducting scientific research.

Now, he's doing it again, but this time he's not leaving the planet.

Pettit is currently in Antarctica on a scientific expedition to look for meteorites. Even though he's still on Earth, the trip will have a lot in common with his ISS stay as part of the Expedition 6 crew. So in addition to the search for meteorites, Pettit will be using his background for another mission -- learning more about how Antarctica can prepare astronauts to travel to the moon and Mars.

"This is an opportunity that appeals to the heart of any explorer, whether an Earth explorer or space explorer," he said. "To be able to go off on a frontier, a place where one's normal intuition no longer applies, is the essence of exploration. When in such a place, new discoveries abound, to be found simply by opening your eyes. And to be able to participate in some meaningful way with other scientific missions and gain the experience for space exploration presents an exceptional opportunity".

"Antarctica is a great match for either lunar or Martian training analogs," he said. "Antarctica has both Mars and moon analogs, depending on where you go on the continent. If you go to the dry valleys, places in Antarctica that have no snow, you have as close to a Mars environment on Earth as you can get. If you stay on the ice sheets, you have more like a lunar setting where the geographic contrast is self-similar without the rich resources that we are use to on a planetary surface (like Earth and Mars). Where we will be going is the ice sheets, and this should be more akin to a lunar analog setting".........

Posted by: Nora      Read more         Source

January 11, 2007, 4:51 AM CT

Research To Solve Aurora Mystery

Research To Solve Aurora Mystery
The aurora is a bright glow observed in the night sky, commonly in the polar zone. For this reason some researchers call it a "polar aurora" (or "aurora polaris"). In northern latitudes, it is known as the aurora borealis, which is named after the Roman goddess of the dawn, Aurora, and the Greek name for north wind, Boreas. Particularly in Europe, it often appears as a reddish glow on the northern horizon, as if the sun were rising from an unusual direction. The aurora borealis is also called the northern lights since it is only visible in the North sky from the Northern Hemisphere. The aurora borealis most often occurs from September to October and from March to April. Its southern counterpart, aurora australis, has similar properties.

NASA will launch the largest number of scientific satellites ever sent into orbit aboard a single rocket. A handful of Alberta researchers will be at Kennedy Space Center watching and waiting. For Dr. Ian Mann and Dr. John Samson, scientists in the Department of Physics at the University of Alberta, the real fun will begin when the satellites start taking measurements in the eye of space storms above observatories spread across North America.

The satellites, all carrying identical suites of electric, magnetic, and particle detectors, are part of the NASA THEMIS mission (for "time history of events and macroscale interactions during substorms"). THEMIS is a collaborative effort of researchers from the US, Canada and Europe that will study processes occurring in near-Earth space and elsewhere in the universe.........

Posted by: Nora      Read more         Source

January 10, 2007, 9:04 PM CT

Automated System Installs Pavement Markers

Automated System Installs Pavement Markers GTRI researcher Colin Usher uses a touch-screen monitor mounted in the cab of the truck.
Credit: Photo by Gary Mee
On rainy nights in Georgia and across the nation, drivers greatly benefit from small, reflective markers that make roadway lanes more visible. A new automated system for installing the markers is expected to improve safety for workers and drivers.

There are more than three million of these safety devices, called raised pavement markers (RPMs), in service on Georgia highways. They are installed and then need to be replaced about every two years by road crews who consider the task one of the riskiest they face. Workers typically ride on a seat cantilevered off the side of a trailer just inches from highway traffic.

Manual RPM placement is not only risky for personnel, but it is also expensive and time-consuming. A typical RPM placement operation includes four vehicles and a six-person crew. All the vehicles must stop at each marker location, so there is tremendous wear on the equipment and increased fuel use.

The Georgia Department of Transportation (GDOT) believed there was a better way to do it and funded the Georgia Tech Research Institute (GTRI) to develop a first-of-its-kind system capable of automatically placing RPMs along the lane stripes while in motion. After almost three years of research and development, GTRI expects to deliver a prototype system early this year. Because of widespread interest in the system, researchers will present a report on their project on Jan. 23 at the National Research Council's Transportation Research Board Annual Meeting in Washington, D.C.........

Posted by: John      Read more         Source

January 10, 2007, 8:53 PM CT

Use Wheat to fatally starve insect predators

Use Wheat to fatally starve insect predators
A newly identified wheat gene produces proteins that appear to attack the stomach lining of a crop-destroying fly larvae so that the bugs starve to death.

The gene's role in creating resistance to Hessian flies was a surprise to U.S. Department of Agriculture and Purdue University researchers, discoverers of the gene and its function. They made the finding as they investigated new, long-term methods to protect wheat from insect damage.

"This is a different kind of defense than we were expecting," said Christie Williams, a USDA-Agricultural Research Service scientist and Purdue Department of Entomology adjunct assistant professor. "Usually we expect the plant to fortify its cell walls or make poisons to use against insects and pathogens".

Instead, the researchers found that a specific protein, called HFR-3, one of a group of substances called lectins, is capable of binding with a carbohydrate complex in the Hessian fly larvae. The lectin acts as a key to the carbohydrate structure, known as a chitin.

When the larvae attack a resistant plant, the plant's lectin production quickly increases by as much as 3,000 times. The larvae then ingest the lectin. This interaction probably damages the larvae's chitin-rich mid-gut lining so that it can't absorb nutrients from the plant, causing the insects starve, Williams said.........

Posted by: Nora      Read more         Source

January 10, 2007, 4:41 AM CT

Dark States In DNA

Dark States In DNA
Chemists at Ohio State University have probed an unusual high-energy state produced in single nucleotides -- the building blocks of DNA and RNA -- when they absorb ultraviolet (UV) light.

This is the first time scientists have been able to probe the "dark" energy state -- so called because it cannot be detected by fluorescence techniques used to study other high-energy states created in DNA by UV light.

The study suggests that DNA employs a variety of means to dissipate the energy it absorbs when bombarded by UV light.

Scientists know that UV light can cause genetic alterations that prevent DNA from replicating properly, and these mutations can lead to diseases such as cancer.

The faster a DNA molecule can dissipate UV energy, the lesser the chance that it will sustain damage -- so goes the conventional scientific wisdom. So the dark states, which are much longer lived than previously known states created by UV light, may be linked to DNA damage.

The existence of this dark energy state -- dubbed n(pi)* (pronounced "n-pi-star") -- had previously been predicted by calculations. Other experiments hinted at its existence, but this is the first time it has been shown to exist in three of the five bases of the genetic code -- cytosine, thymine and uracil.........

Posted by: Nora      Read more         Source

January 9, 2007, 8:51 PM CT

Light-emitting Decay of Neutrons

Light-emitting Decay of Neutrons Credit: Zina Deretsky, National Science Foundation
Neutrons -- the tiny particles that match with protons to form the innards of nearly every atom in the universe -- decay when left to fend for themselves outside an atomic nucleus. For decades, scientists have predicted but never proved that roughly 1 in 1,000 of those decays will produce light in the form of an energetic photon.

Now, for the first time, scientists have caught the photons from that "radiative decay" in action. Reporting in the Dec. 21, 2006, issue of Nature, a team of scientists from the United States and Britain show results that may confirm neutron radiative decay.

In addition to helping to prove a theory, the findings shed light on the intricacies of the so-called "weak force," which, along with gravity, the electromagnetic force and the strong force, form the four fundamental forces of nature.

"This is the first experiment to make a definitive detection of these rare photons," said Fred Wietfeldt, assistant professor of physics at Tulane University. "The next step is to make more precise measurements of their energy, direction and polarization. This opens the door to a new class of experiments to further elucidate the weak force and perhaps find hints of new physics".

While within an atom's nucleus, neutrons and protons are bound together, and only under certain conditions do the neutrons decay. When removed from the atom, neutrons decay rapidly with a half-life of only 10 minutes, each breaking down to produce a proton, an electron and an antineutrino, and rarely, a photon.........

Posted by: John      Read more         Source

January 9, 2007, 8:45 PM CT

Universe's Oldest Objects

Universe's Oldest Objects
The deepest reaches of space are permeated by a cloak of infrared radiation, an uneven energy swath generated by long-dead objects from the early universe.

Now, scientists have teased apart overlapping signals from that cosmic infrared background, building upon an earlier study to show that uneven patches of energy may actually be clusters of the first objects to emerge from the Big Bang.

The astronomers believe the objects are either extremely bright stars more than 1,000 times more massive than our sun, or quasars, large black holes that consume enormous amounts of gas and debris and re-emit the materials in almost unparalleled bursts of energy. If the patches are star clusters, they may be the first galaxies, smaller than most known galaxies yet containing a mass on the scale of 1 million suns.

With a grant from the National Science Foundation, scientists studied archival data from the calibration of the NASA Spitzer telescope and conducted several stages of cleaning to remove signals from more recent galaxies and other objects to get to the underlying signals.

"Observing the cosmic infrared background is like watching distant fireworks from within a brightly lit city," said lead author Alexander Kashlinsky of NASA's Goddard Space Flight Center in Greenbelt, Md. "It's as if we have turned off the city lights one by one to see the bursts more clearly. While we can't resolve each spark in the fireworks, we can see the large scale structures and their glow".........

Posted by: Edwin      Read more         Source

January 8, 2007, 9:32 PM CT

New Stars Shed Light On The Past

New Stars Shed Light On The Past
new image from the Hubble Space Telescope shows N90, one of the star-forming regions in the Small Magellanic Cloud. The rich populations of infant stars found here enable astronomers to examine star forming processes in an environment that is very different from that in our own Milky Way.

This new image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope depicts bright blue newly formed stars that are blowing a cavity in the centre of a fascinating star-forming region known as N90.

N90 is located in the wing of the Small Magellanic Cloud, in the constellation of Tucana, approximately 200,000 light-years away from the Earth. Its proximity makes it an exceptional laboratory to perform in-depth studies of star formation processes and their evolution in an environment close to that in the early Universe. Dwarf galaxies such as the Small Magellanic Cloud, with small numbers of stars compared to our own Milky Way, are considered to be the primitive building blocks of larger galaxies. The study of star formation within this dwarf galaxy is particularly interesting to astronomers because its primitive nature means that it lacks a large percentage of the heavier elements that are forged in successive generations of stars through nuclear fusion.........

Posted by: Edwin      Read more         Source

January 7, 2007, 9:41 PM CT

Chemistry of Volcanic Fallout

Chemistry of Volcanic Fallout Joel Savarino collecting snow samples at Dome C
Credit: Joel Savarino, CNR
A team of American and French scientists has developed a method to determine the influence of past volcanic eruptions on climate and the chemistry of the upper atmosphere, and significantly reduce uncertainty in models of future climate change.

In the January 5 issue of the journal Science, the researchers from the University of California, San Diego, the National Center for Scientific Research (CNRS) and the University of Grenoble in France report that the chemical fingerprint of fallout from past eruptions reveals how high the volcanic material reached, and what chemical reactions occurred while it was in the atmosphere. The work is particularly relevant because the effect of atmospheric particles, or aerosols, is a large uncertainty in models of climate, according to Mark Thiemens, Dean of UCSD's Division of Physical Sciences and professor of chemistry and biochemistry.

"In predictions about global warming, the greatest amount of error is associated with atmospheric aerosols," explained Thiemens, in whose laboratory the method, which is based on the measurement of isotopes-or forms of sulfur-was developed. "Now for the first time, we can account for all of the chemistry involving sulfates, which removes uncertainties in how these particles are made and transported. That's a big deal with climate change".........

Posted by: Nora      Read more         Source

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