(Figure 1)

Physicists in Austria have created a new type of stable bound state made from two atoms that repel each other. This counterintuitive result--normally we think that two objects need to attract each other to stick together-- was obtained by a team led by Johannes Hecker Denschlag and Andrew Daley at the University of Innsbruck by trapping ultracold rubidium atoms in an optical lattice, NaturalScience reported.
The work could have implications for making quantum computers and to study bound states on a fundamental level. The experiment also shows how optical lattices can be used to investigate many-body phenomena that are hard to observe in other systems.

(Figure 2)

To make two objects bind together, you normally need to make them attract one another. Now, however, Denschlag and colleagues have shown that this is not always necessary and that objects can stick together even when there is a repulsive force between them. This is counterintuitive because in free space repulsive pairs cannot exist: if you bring two repelling objects together they will just accelerate away from each other (figure 1).
Denschlag and colleagues have demonstrated that this problem can be overcome by placing the objects in a 3D optical lattice. This is an artificial “crystal“ of light formed by the interference of multiple laser beams. The crystal contains potential wells or “dimples“ in which atoms can be trapped (figure 2).
The Austrian team began by preparing a sample of ultracold rubidium-87 molecules from a Bose-Einstein condensate (BEC) of rubidium atoms. A BEC is a collection of particles that has been cooled to such low temperatures that all the particles collapse into the same quantum state.
Next, the physicists loaded the rubidium-87 molecules into the optical lattice. By then splitting the molecules in a very controlled way using an applied magnetic field (with the help of a so-called Fesbach resonance), they obtained pairs of atoms that strongly repelled each other. Each potential well contained either one repulsive pair of atoms or none at all.
According to the team, the bound configuration is stable because the total energy of the atoms is smaller when they are close together than when they are separate.

The Alzheimer’s drug Aricept not only improves memory and understanding in patients but appears to slow the characteristic shrinkage of the brain, CNN quoted researchers as saying.
Magnetic resonance imaging or MRI images of the brains of 131 patients with mild cognitive impairment showed less shrinkage of the hippocampus, a structure key to memory function, in patients who got the drug compared to those who got a placebo, researchers told a meeting.
“No drug has been shown to slow brain atrophy for patients with mild cognitive impairment,“ said Dr. Clifford Jack of the Mayo Clinic in Rochester, Minnesota.
Aricept, which is known generically as donepezil, is marketed by Pfizer and Japan’s Eisai Co. Ltd.
“Our study results seem to imply that donepezil does more than provide symptom relief--it has an effect on a measure of brain health. Our findings also show that MRI measures can have usefulness in future studies of mild cognitive impairment.“
Mild cognitive impairment can lead to Alzheimer’s disease, but not always.
Jack’s team found the effects only in people with the a polipoprotein E4 (APOE 4) gene, a genetic variation that has long been known to put people at higher risk of Alzheimer’s.
Why is unclear, he said.
“One possibility is that APOE 4 carriers were more likely to have definite Alzheimer’s disease than noncarriers in the study who appear to have symptoms of early Alzheimer’s disease, yet turn out to have a different diagnosis when an autopsy is performed after death,“ he said.
Jack’s study was presented to the International Conference on Alzheimer’s Disease and Related Disorders in Madrid, Spain.
An estimated 12 million people worldwide suffer from Alzheimer’s disease, but international researchers predict the number of people suffering from dementia worldwide could reach 81 million by 2040 as the “baby boom“ generation ages.
There is no cure for Alzheimer’s, which begins as mild memory loss and can progress quickly to complete loss of any ability to care for oneself.
The brain becomes clogged with proteins known as plaques and tangles of nerve fobers. And it shrinks.
“In extreme cases, the brain of an Alzheimer’s patient might weigh half of what a normal person’s brain does at peak health,“ Jack said.
Experts are looking for ways to prevent Alzheimer’s from developing, or to slow its fatal progression. They are also looking for better ways to diagnose the disease in patients using imaging scans such as MRI or PET.

Hydra and Nix are about 5000 times fainter than Pluto and roughly two to three times further from the planet than its largest moon Charon. (Google Photo)

Two new small moons of Pluto, which were discovered by the Hubble Space Telescope last year, have been officially christened Hydra and Nix. Previously they were known rather boringly as P1 and P2. The new names were approved by the International Astronomical Union (IUA)--the official body that assigns names to celestial objects, Google said.
First photographed by Hubble in May 2005, Hydra and Nix are about 5000 times fainter than Pluto and roughly two to three times further from the planet than its largest moon Charon, which was discovered in 1978. The more distant of the two new moons (P1) is now known as Hydra, while Nix is the new name for the inner satellite (P2).
Although the members of the team who discovered the moon wanted to call the inner satellite Nyx, that name was already bagged by asteroid 3908. The IAU therefore changed Nyx to its Egyptian equivalent, Nix.
In Greek mythology, Nyx was the goddess of darkness and night and so is a good name for a moon orbiting Pluto--the god of the underworld. Nyx was also the mother of Charon, the sulky old boatman who ferried the dead into Hades. This name therefore alludes to the theory that a giant impact created Pluto’s satellites and that Charon was created from the same material as Nix. Hydra, meanwhile, was a nine-headed serpent monster, loosely related to the fact that moon is orbiting Pluto, the ninth planet in the solar system.
There are further connections too. Just as Pluto’s name begins with the letters “P“ and “l“ to pay tribute to astronomer Percival Lowell, whose work led to the discovery of the planet in 1930, so Nix and Hydra honor the “New Horizons“ mission because they start with the letters “N“ and “H“. New Horizons, which was launched in January this year, is the first spacecraft to visit Pluto and its moons. If you can bear any more of this, note that the first letter of Hydra also honors the Hubble Space Telescope.

Although technically more challenging, laparoscopic Roux-en-Y gastric bypass, a common type of stomach bypass operation, provides greater weight loss in severely obese patients than does placing a plastic band around the stomach to make it smaller, new research shows.
According to Reuters, stomach bypass is also more likely than banding to promote the resolution of diseases often seen in obese patients, such as high blood pressure and diabetes.
Although multiple trials have compared the two procedures, this is the first study to focus specifically on patients with a BMI greater than 50--with super morbid obesity-- Dr. George Ferzli and his associates report in their article, published in the Archives of Surgery.
BMI is a measure of body weight for height. Values between 20 and 25 are typically considered normal. Any value of 30 or greater is considered obese.
This information is vital for patients considering weight loss surgery, Ferzli told Reuters Health, “because proper patient and procedure selection, proper follow-up, and proper long-term support are quite important in achieving the desired outcome.“
At the SUNY-Health Science Center of Brooklyn in Staten Island, New York, patients undergoing weight loss surgery decided which procedure would be performed, after receiving extensive counseling. To be eligible, the patients had to complete a supervised dietary and exercise program of 8 to 12 months without maintaining weight loss.
Ferzli performed more than 315 weight loss procedures between February 2001 and June 2004. Among 106 super morbidly obese patients, 60 underwent stomach banding and 46 underwent stomach bypass.
Stomach bypass took longer perform in the OR than did stomach banding. Moreover, patients treated with stomach bypass were hospitalized for a day or two longer. There were no differences between the operations in the rate of early complications.
After 30 days, however, patients treated with stomach bypass had fewer complications than those treated with banding and also lost more weight.
“In our experience, laparoscopic Roux-en-Y gastric bypass appears superior to laparoscopic adjustable gastric banding in super morbidly obese patients,“ Ferzli and his associates conclude in their paper.
There is a subset of severely obese patients for whom gastric band would be more appropriate, Ferzli added. “We now reserve gastric banding to patients who cannot have gastric bypass surgery, because of such conditions as liver disease or (stomach disease) and ulceration that require frequent endoscopy.“

Geophysicists in the US have found that the “aftershocks“ produced by earthquakes are triggered by “dynamic“ seismic waves from the main shock rather than changes in stress in nearby faults brought about by the rearrangement of the Earth’s crust.
Karen Felzer of the US Geological Survey and Emily Brodsky at the University of California at Santa Cruz obtained their results by analyzing the aftershocks produced by thousands of small to medium-sized earthquakes that took place in Southern California over nearly two decades. The work could have implications in predicting where aftershocks occur, Physicsweb wrote.
Earthquakes occur as a result of the pressure that builds up between continental plates moving relative to one another in the Earth’s crust. These primary quakes then generate large numbers of aftershocks--secondary shocks that can occur at some distance from the earthquake’s epicenter and also up to a day or two later. Until now, scientists believed that it was changes in the “static stress“ brought about by an earthquake that was responsible for its aftershocks since it seemed that only this mechanism could generate aftershocks that take place significantly after the main quake. But Felzer and Brodsky have concluded this is not the case.
The researchers looked at data on the precise locations of thousands of magnitude 2 to 6 earthquakes that occurred in Southern California between 1984 and 2002. They found that the number of aftershocks drops off steeply with increasing distance from the main shock, up to a distance of 50km. More precisely, they found that the frequency of aftershocks decays with distance as a single inverse power law with an exponent of around -1.35. They say this smooth trend means a single triggering process operates over the entire range, and that because static stress is negligible at distances approaching 50 km “dynamic stress“ must be the culprit. They also point out that seismic waves also decay quickly with distance following a power-law relation.

A cloned human would probably consider itself to be an individual, a study suggests.
Scientists drew their conclusions after interviewing identical twins about their experiences of sharing exactly the same genes with somebody else, BBC reported.
The team said the twins believed their genes played a limited role in shaping their identity.
Co-author Dr Barbara Prainsack, from the University of Vienna, Austria, who worked with Professor Tim Spector, from the Twins Research Unit, St Thomas’ Hospital, London, said: “The birth of Dolly the sheep triggered many questions about what it would be like to be a clone.
“We don’t have clones we can interview--but we do have identical twins.“
Identical twins are created when a single egg, fertilized by a single sperm, splits into two separate, but genetically identical, embryos.
The researchers said because twins--like potential clones--share the same genes, they offer the only existing method of studying the feelings a clone might experience.
But they also emphasized twins would differ from clones because they are born at the same time, whereas clones would differ in age.
The scientists carried out 17 interviews of identical, non-identical and non-twin siblings.
The identical twins said being a twin did not compromise their individuality--although they pointed out that people often had preconceptions that they were one of a pair rather than individuals.
Those interviewed viewed being an identical twin as a blessing, and said they would not rather be a non-identical twin or a “singleton“.
They also said they believed their genes had no great bearing on their relationship with their twin and their identity.
The twins felt factors such as being brought up in the same environment, having spent a large part of their lives together, and being treated in a similar way by their parents were more important.