Astronomers may have identified the remains from this ancient stellar explosion, now considered the oldest supernova on record. (Google Photo)

Nearly 2,000 years ago, Chinese astronomers spotted a bright light materializing in the night sky. Turns out the skywatchers had witnessed the spectacular explosion of a dying star.
That was the year 185 AD. Tuesday astronomers said they might have identified the remains from this ancient stellar explosion, now considered the oldest supernova on record, Space.com reported.
“I think it is very interesting that we can now say with some confidence, but not absolute certainty, that RCW 86 is the remnant of A.D. 185,“ said Jacco Vink of the University of Utrecht, the Netherlands.
In the Astrological Annals of the Houhanshu, Chinese astronomers noted the bright light in the sky twinkled like a star but didn’t appear to move, arguing against the object being a comet. Within eight months, they recorded, the bright light faded, a phenomenon that astronomers now know is consistent with supernovas.
When a star that’s more than eight times the mass of our sun burns out, gravity’s inward tug tears apart the star’s innards. It collapses and then rebounds.
Called a supernova, the explosion propels jets of high-energy light and matter out into space. The hurling remains and the material they encounter are heated to millions of degrees and can emit intense X-ray radiation for thousands of years.
Astronomers had suggested the stellar material called RCW 86 could be leftovers from the 185 AD supernova, based on historical records of the object’s position in the sky. But previous work estimated the object was 10,000 years old, which led to doubts about the link.
Astronomers led by Vink studied the material in RCW 86 to determine when its progenitor star originally exploded within the Southern Hemisphere constellation Centaurus. To do this, they used the X-ray capabilities of NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton Observatory.
RCW 86 is encased in an expanding shock wave formed during its transit from the original explosion. By peering into one part of RCW 86, the astronomers calculated how fast this cosmic bubble was moving. So with the size and speed of RCW 86, the astronomers could calculate the time of the explosion, and hence the remnant’s age.
“Our new calculations tell us the remnant is about 2,000 years old,“ said Aya Bamba, a coauthor from the Institute of Physical and Chemical Researcher in Japan.

Youthful Star
The new age estimate matches the supernova spotted in 185 AD. But this calculation means the remnant is 8,000 years younger than previously thought.
The astronomers said the difference can be attributed to the irregular shape of the remnant’s expanding bubble. Stellar wind from the progenitor star pushed some of the remnant’s gases in a certain direction, forming a dense pile.
“The idea for RCW 86 is that in some regions the shock has hit this piled-up material. In those regions the shock will start moving slower,“ Vink said. And in other regions, the shock wave is much speedier.
“This could explain the earlier measurements for lower shock velocities,“ Vink told SPACE.com. The previous speeds were used to calculate RCW 86’s age.

Astronaut Edwin E. Aldrin Jr. walking on the surface of the moon, July 20. (AFP File Photo)

Radiation encountered on extended trips to the Moon or Mars could harm astronauts’ brains, experiments on rats suggest. The space farers could face problems with spatial learning, memory and stress, NewScientist wrote.
Astronauts aboard the space shuttle and the International Space Station are largely protected from space radiation by the Earth’s magnetic field. But the crew of a mission to Mars could spend three years outside this protective bubble.
So NASA recently awarded funding for 12 projects that will investigate how long-term radiation exposure in interplanetary space could potentially cause health problems in astronauts.
One award will help continue studies of how radiation affects the behavior and cognitive abilities of rats. It is led by Bernard Rabin of the University of Maryland in Baltimore, US.
Rabin’s work over the past several years has already shown worrisome effects. He has been focusing on the effects of heavy particle radiation, which is made up of fast-moving nuclei from heavy elements like iron.
These are more difficult to shield against than lighter elements, and Rabin’s studies suggest that they are more potent in affecting the brain. The team beams heavy particles into the brains of rats using particle accelerators, then tests the rats to see how the radiation affects their cognitive abilities.
Rats whose brains have been exposed to heavy particle radiation perform more poorly in navigating mazes and have a harder time learning to press a button to get a food pellet. They also are more easily distracted and experience more anxiety in stressful situations.
The effects are apparent in rats given as little as 0.5 gray of radiation, which is small enough that the rats live out their normal lifespan. That amount is comparable to the levels that astronauts would face on a Mars mission, Rabin says. He notes, however, that the radiation is delivered to the rats in one brief burst, whereas the astronauts’ exposure would be spread out over several years--a difference that could potentially affect the results.
Still, the radiation could impair astronauts’ abilities on these long-duration missions. “If you’ve got to locate an object in space and you can’t, that presents some problems,“ Rabin told New Scientist.
Changes in the astronauts’ response to stress might also cause problems, he says: “If there’s an increase in the level of anxiety, for example, the astronauts are not going to be willing to explore as much. Or if there’s a decrease in anxiety, they might be taking chances that aren’t wise.“
It may be possible to develop an antidote for the radiation, however. One of Rabin’s studies showed that rats given strawberry and blueberry extracts before being irradiated were less prone to its harmful effects.
This could be because the extracts contain antioxidants. Researchers still do not know exactly how heavy particle radiation creates cognitive problems, but it is known to create highly reactive oxygen-containing molecules in the body.

US scientists have developed a system allowing the simultaneous creation of 55,000 identical patterns drawn with tiny dots of molecular ink.
According to UPI, each two-dimensional array drawn on substrates of gold or glass is a single molecule tall. That, said the Northwestern University scientists, is an advance of a patterning method called Dip-Pen Nanolithography.
To demonstrate the technique, researchers reproduced the face of Thomas Jefferson from a 5-cent coin 55,000 times within 30 minutes. Each identical image was 12 micrometers wide--about twice the diameter of a red blood cell--consisting of 8,773 dots, each 80 nanometers in diameter.
The advantage of DPN, a maskless lithography, is it can be used to deliver many different types of inks simultaneously to a surface in any configuration one desires.
’This development should lead to massively miniaturized gene chips, combinatorial libraries for screening pharmaceutically active materials and new ways of fabricating and integrating nanoscale or even molecular-scale components for electronics and computers,’ said study leader Professor Chad Mirkin, director of Northwestern`s International Institute for Nanotechnology.
The research is detailed in the current online edition of the journal Angewandte Chemie.

A new computer-aided analysis technique may help spot early signs of Alzheimer’s disease, according to new research, Reuters said.
As Alzheimer’s disease progresses, cells in the brain may become damaged, which allows water molecules to move throughout the brain more freely, Healthday said.
This process of cellular damage causes an increase in the “apparent diffusion coefficient,“ or ADC, which is a measurement used to study the distribution of water in the brain.
A new study included in the October issue of Radiology looked at 13 elderly people with mild cognitive impairment--a risk factor for Alzheimer’s disease--and 13 people without mild cognitive impairment.
The participants underwent magnetic resonance imaging (MRI) of the brain and performed memory-recall tasks.
The MRIs used a new computer-aided analysis program to measure ADC values in different regions of the brain.
The University of California, Irvine researchers found that the participants with mild cognitive impairment had increased water content in certain regions of the brain, including white-matter areas, the hippocampus, temporal lobe gray matter and the corpus callosum.
The ADC values in the hippocampus were associated with worse memory-performance scores.
The new computer mapping technology may allow researchers to learn how Alzheimer’s disease develops in the brain and come up with new strategies for treating the disease.
“Our methods may enable earlier diagnosis of Alzheimer’s disease, allowing earlier intervention to slow down disease progression,“ said researcher Min-Ying Su.

A map of the mouse brain down to details of individual cells has been completed, the first project of an institute funded by Microsoft Corp. co-founder Paul G. Allen, it was announced Tuesday.
The new Allen Brain Atlas is being made available online without cost to neuroscientists studying brain circuits and chemistry, a potential boon to cancer and other disease research because of similarities between the brains of mice and human beings, according to a statement issued by the Allen Institute of Brain Science, Reuters said.
“We want people to use this and make discoveries,“ Dr. Allan Jones, the institute’s chief scientific officer, told The Seattle Post-Intelligencer.
Because more than 90 percent of the same genes are found in mice and humans, the mouse brain map can be compared with genetic findings related to human neurological disorders.
Moreover, the mapping project has shown that 80 percent of the body’s genes are switched on in the brain, compared with 60 percent to 70 percent in previous scientific estimates, Jones said.
Neurosurgeons at Swedish Medical Center in Seattle have begun using the atlas to study the genetics of brain cancers, said neuroscientist Marc Tessier-Lavigne, an institute science adviser who discovered the molecules that trigger connections between nerve cells.
“This really just bolts us ahead in our ability to understand brain function and brain disorder,“ Tessier-Lavigne told The Seattle Times.
Even before completion of the mouse brain map, the institute’s work had become vital to scientists delving into the genetics of multiple sclerosis, which is caused by degeneration of nerve cells, said Dr. Ben Barres, a Stanford University neurology professor.

Using computers to read mammograms can significantly speed up the detection of breast cancer, according to research.
The study found that breast X-rays scanned by a computer as well as a radiologist were as successful as those read by two radiologists.
In some cases, write the authors in the journal Radiology, the new combination was even better at spotting tumors, BBC reported.
The study by Cancer Research UK scientists uses software called Computer Aided Detection, or CAD.
The program scans mammograms for any suspicious features that may indicate a tumor and then highlights the irregularities on screen.
CAD technology is already available in the US and some European countries, but has not been assessed for UK breast screening.
To assess the efficiency of CAD, researchers used more than 10,000 mammograms taken in 1996 that had been previously assessed by two clinicians, which is the standard method for checking for cancers.
The X-rays were then scanned by CAD, and assessed by a radiologist who double-checked any areas highlighted by the computer.
The study found that the cancer detection rate using CAD was at least as good as the traditional method, and in some cases even more successful.
Professor Fiona Gilbert, a radiologist from Aberdeen University, who led the study, said: “The results of this trial are very encouraging.
“We have now embarked on a new study to confirm that the CAD result is still as good when used in real day-to-day decision-making about breast cancer diagnosis.“
The new prospective trial will look at 30,000 women in three breast screening centers in the UK.
Professor Stephen Duffy, an epidemiologist for Cancer Research UK, who also worked on the study, said: “The great advantage of CAD is that, if we confirm the very promising results of this study in a prospective trial, it could help manpower problems in the breast screening service.
“The CAD system would free-up hundreds of radiologists to work on more mammograms as only one instead of two would be required to work on each X-ray.“
Dr Sarah Rawlings, head of policy and information at Breakthrough Breast Cancer, said: “The results of this study are very positive and we look forward to further trials which will tell us if this technique could be routinely used.
“The use of new technology in addition to standard breast screening is to be welcomed, however we know that some women aren’t currently attending their screening appointments.
“Early detection is vital to improving the chance of survival. We advise those aged 50-70 to accept their screening invites or request a mammogram if over 70.“