By modeling a red giant with a fully 3D hydrodynamic code, LLNL researchers identified the mechanism of how and where low-mass stars destroy the ÅHe that they produce during evolution. (Google Photo)

Using 3D models run on some of the fastest computers in the world, Laboratory physicists have created a mathematical code that cracks a mystery surrounding stellar evolution, .Llnl.gov said.
For years, physicists have theorized that low-mass stars (about one to two times the size of our sun) produce great amounts of helium 3 (ÅHe). When they exhaust the hydrogen in their cores to become red giants, most of their makeup is ejected, substantially enriching the universe in this light isotope of helium.
This enrichment conflicts with the Big Bang predictions. Scientists theorized that stars destroy this ÅHe by assuming that nearly all stars were rapidly rotating, but even this failed to bring the evolution results into agreement with the Big Bang.
Now, by modeling a red giant with a fully 3D hydrodynamic code, LLNL researchers identified the mechanism of how and where low-mass stars destroy the ÅHe that they produce during evolution.
They found that ÅHe burning in a region just outside of the helium core, previously thought to be stable, creates conditions that drive this newly discovered mixing mechanism.
Bubbles of material, slightly enriched in hydrogen and substantially depleted in ÅHe, float to the surface of the star and are replaced by ÅHe-rich material for additional burning. In this way the stars destroy their excess ÅHe, without assuming any additional conditions (like rapid rotation).
“This confirms how elements evolved in the universe and makes it consistent with the Big Bang,“ said David Dearborn, a Lawrence Livermore National Laboratory physicist. “The previous one-dimensional model did not recognize the instability created by burning ÅHe.“
The same process applies to low-mass metal poor suns, which may have been more important than metal-rich stars like the sun throughout the earlier part of galactic history in determining the ÅHe abundance of the interstellar medium.
The research appears in the Oct. 26 edition of Science Express.
The Big Bang is the scientific theory of how the universe emerged from a tremendously dense and hot state about 13.7 billion years ago.
The Big Bang produced about 10 percent 4He, .001 percent ÅHe with almost the rest made up of hydrogen.
Later, low mass stars should have increased that ÅHe production to .01 percent. However, observations of ÅHe in the interstellar medium show that it remains at .001 percent. So where did that ÅHe go?
That’s where the Livermore team comes in. Livermore scientists Peter Eggleton and Dearborn collaborated with John Lattanzio of the Centre for Stellar and Planetary Astrophysics in Australia to create a code that describes how ÅHe burns during star formation so that the makeup of the universe after the Big Bang is reconciled.
“Prior to our work, it was perceived that the ÅHe in the envelope was largely indestructible, and would be blown off later into space, thus enriching the interstellar medium and causing the conflict with the Big Bang,“ said Eggleton, an astrophysicist and lead author of the paper. “What we find is that ÅHe is unexpectedly destructible, by a mixing process driven by a phenomenon that has been ignored so far.“
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy’s National Nuclear Security Administration.

Duke University engineers have shown that a three-dimensional ultrasound scanner they developed can successfully guide a surgical robot, EureKalert reported.
The scanner could find application in various medical settings, according to the researchers. They said the scanner ultimately might enable surgeries to be performed without surgeons, a capability that could prove valuable in space stations or other remote locations.
“It’s the first time, to our knowledge, that anyone has used the information in a 3-D ultrasound scan to actually guide a robot,“ said Stephen Smith, professor of biomedical engineering at Duke’s Pratt School of Engineering.
The work was supported by the National Institutes of Health and the National Science Foundation.
In their demonstration, the researchers used 3-D ultrasound images to pinpoint in real time the exact location of targets in a simulated surgical procedure. That spatial information then guided a robotically controlled surgical instrument right to its mark.
The scanner could be coupled to the surgeon-operated robots that are being increasingly used for performing minimally invasive “laparoscopic“ surgeries on the heart or other organs, Smith said. In such operations, surgeons work through tiny “keyhole“ incisions, and the new scanner would provide surgeons a more realistic view of the organ they are working on.
“All the technology is available,“ Smith said. “We just need to make the connections between the ultrasound scanner and the robots now in use by surgeons. There are no technological barriers to doing that right away.“
Among other applications, surgeons could use the 3-D scanner to spot potential tumors in real time during biopsy procedures, making a diagnosis of cancer harder to miss, the engineers said. Physicians today must rely on still images, such as CT scans, of a patients’ organs captured prior to biopsy to locate lesions suspected to be cancer.
As artificial intelligence technology improves in the coming decades, the scanner might even be able to guide surgical robots without the help of a surgeon, the researchers said.
The 3-D ultrasound probe has yet to be tested in human patients, Smith said, but he added that his team believes the technology is ready for clinical trials.
The Duke team in 1987 developed the first-ever 3-D ultrasound scanner for imaging the heart in real time from outside the body. As technology enabled ever smaller ultrasound arrays, the researchers engineered probes that could fit inside catheters threaded through blood vessels to view the vasculature and heart from the inside.
The team has since demonstrated that the scanner also can be used to laparoscopically image other organs, including the spleen, liver and gall bladder.

Physicists are drawing up plans for a new space mission that could carry out a range of experiments in fundamental physics. The mission, which would involve placing an atom interferometer aboard a spacecraft, aims to observe the effects of quantum gravity for the first time. Other instruments will look for violations of the equivalence principle--one of the foundations of general relativity--as well deviations in Newtonian gravity, which would reveal the existence of higher dimensions. They could even search for hypothetical “dark matter“ particles called axions, Physicweb wrote.
The plans are being drawn up by Tim Sumner of Imperial College London, who intends to submit them to the European Space Agency (ESA) later this year. If approved, the mission would cost about Euro 250m and could take off by 2015. Dubbed the GrAnd Unification and Gravity Explorer (GAUGE), the mission also involves researchers from elsewhere in the UK and Europe. It builds on earlier proposals called HYPER and STEP, which would also have carried out tests of fundamental physics but were not selected by ESA for launch.
Now, however, Charles Wang--a theorist from Aberdeen University--has given added scientific motivation to the GAUGE mission. He has shown that an atom interferometer could detect distortions in spaceÐtime caused by “gravitons“--particles that are believed to mediate gravity at the “Planck scale“ at which all the laws of physics are unified. Studying physics at the Planck scale, which occurs at lengths of about 10Ð35 m and times of about 10Ð43 s, would be impossible with current particle accelerators.
According to Wang and his collaborators from the CCLRC’s Centre for Fundamental Physics near Oxford, gravitons constantly stretch and squash the geometry of spaceÐtime, a bit like the way in which pollen or smoke particles in air have a random Brownian motion as they are buffeted by much smaller molecules. By observing these tiny distortions in an atom interferometer, Wang and his collaborators think it will be possible to extract information on the gravitons and understand their underlying physics.
The experiment aboard GAUGE will involve sending beams of ultracold atoms down two identical arms of an interferometer. Fluctuations in spaceÐtime caused by the gravitons will randomly modulate the time it takes for the beams to travel down the arms. This will then create a slight fuzziness in the fringe patterns that are created when the beams interfere. Such decoherence experiments are much harder on Earth, where the effects of gravity are tricky to eliminate.
Giovanni Amelino-Camelio, a quantum-gravity phenomenologist from the University of Rome “La Sapienza“, thinks that Wang’s paper is an important step in transforming an idea first raised by Ian Percival of Queen Mary, University of London, into something that can be experimentally tested. “This work should provide additional motivation for matter-interferometric studies in space,“ says Amelino-Camelio. “It is not obvious that the effect should go excatly as described in this paper, but the fact that final some valuable new tools of analysis are being introduced for this type of matter-interferometric studies is encouraging.“

High-quality vaccines can reduce the level of illness and prevent emergence of variants. (Google Photo)

Scientists have discovered a new strain of bird flu that appears to sidestep current vaccines. It’s infecting people as well as poultry in Asia, and some researchers fear its evolution may have been steered by the vaccination programs designed to protect poultry from earlier types of the H5N1 flu.
According to AP, the new variant has become the primary version of the bird flu in several provinces of China and has spread to Hong Kong, Laos, Malaysia and Thailand, the researchers report. It is being called H5N1 Fujian-like, to distinguish it from earlier Hong Kong and Vietnam variants.
“We don’t know what is driving this,“ report co-author Dr. Robert G. Webster of St. Jude’s Children’s Research Hospital in Memphis, Tenn., said in a telephone interview.
New vaccines will have to be developed, Webster said.
Many scientists are going to think the vaccination program encouraged the virus to evolve resistance, he added, but high-quality vaccines can reduce the level of illness and prevent emergence of variants.
While the new virus has infected people, there is no evidence that it can pass easily from person to person, Webster said.
However, he added, “this virus is continuing to drift.“
Dr. Michael L. Perdue, of the World Health Organization’s Global Influenza Program in Zurich, Switzerland, said the new variant doesn’t indicate any increased risk for people “other than the fact it seems to be pretty widespread.“
The virus is continuing to change, he added.
Perdue, who was not part of Webster’s research team, said WHO is working with the Chinese Ministry of Health to develop a vaccine for the new form of the virus.
The H5N1 flu has devastated poultry in China and several other southeast Asian countries and also has claimed more than 150 human lives. Most of the people affected lived close to flocks of chickens or other poultry.
Public health authorities fear that the virus will mutate into a form that can spread easily among people, raising the potential for a worldwide pandemic like the one that killed millions in 1918. That worry has spurred efforts to develop vaccines for the virus as well as to test migrating wildfowl in an effort to detect movement of the disease.
Studding the virus’ surface are two proteins called hemagglutinin--the H in H5N1--and neuraminidase, the “N.“ There are 16 known hemagglutinin versions and nine neuraminidases.
They also trigger the immune system to mount an attack, particularly hemagglutinin, the protein the body aims for when it makes flu-fighting antibodies.
The research was funded by the Li Ka Shing Foundation, a Hong Kong group that supports medical, educational and cultural work, and the US National Institute of Allergy and Infectious Disease.

Insulin-secreting cells have been created from human embryonic stem cells for the first time, raising hopes of a limitless supply of cells that could be transplanted into people with type 1 diabetes, NesScientist said.
Emmanuel Baetge and his colleagues at Novocell in San Diego, California, used a cocktail of chemicals to coax the stem cells to form pancreatic cells.
The cells produce as much insulin as normal pancreatic islet cells, but unlike adult islet cells, this doesn’t appear to be regulated by sugar levels. Baetge is confident they can overcome this problem.
If they succeed, the company has also developed a way to coat the cells in a polymer called polyethylene glycol, which would prevent them from being rejected by the recipient’s immune system, while allowing sugar, insulin and other signaling molecules to filter in and out.