The little star's mass grows gradually, eventually reaching a tipping point, when the top layer ignites in a thermonuclear explosion and expels the surface into space.

Explosions of small stars, long thought to create stellar dust, actually sweep dust away, scientists discovered.
For years, researchers have observed swirling dust clouds around systems called recurring novas, which periodically explode, according to Space.com.
New images of a distant nova have now overturned astronomers’ long-standing assumption that the dust originates in the blasts.
Scientists recently observed the RS Ophiuchi system, where a small white dwarf star and large red giant orbit each other. Over time, the giant sheds its outer layer of gas, which the dwarf sweeps up.
The little star’s mass grows gradually, eventually reaching a tipping point, when the top layer ignites in a thermonuclear explosion and expels the surface into space. The process then starts over--astronomers have already seen this system “go nova“ in 1898, 1933, 1958, 1867 and 1985.
When RS Ophiuchi blew again in February 2006, researchers took advantage of a new instrument, called the Keck Nuller, at the W. M. Keck Observatory in Mauna Kea, Hawaii, to watch the event in action. The Nuller used two giant telescopes to block out the overwhelming light from the explosion so scientists could study its fainter surroundings.
They were surprised to see no dust in the bright zone around the star and only to see dust farther away, where the blast wave had not yet reached. The researchers surmised that the detonation had vaporized nearby dust particles, and that the outer dust must have been created before the bang.
“This flies in the face of what we expected,“ said Richard Barry, an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Md., who headed up the observations. “Astronomers had previously thought that nova explosions actually create dust.“
The team suspects the dust is really produced when the white dwarf plows through the red giant’s trail of debris, creating patches of gas where atoms are cool and dense enough to clump together into dust particles.

The first in a new class of HIV drugs has become available in the UK.
It means doctors will have a further treatment option for patients who have built up resistance to existing drugs.
Raltegravir is an integrase inhibitor, which works by blocking an enzyme essential for HIV to be able to replicate itself, BBC said.
An estimated 73,000 people live with HIV in the UK. Raltegravir will be reserved for those who have stopped responding to other treatment.
Resistance to HIV medication is becoming increasingly common - more than one in 10 UK patients with HIV has some level of resistance to at least one drug before they have even begun therapy, research has shown.
A clinical trial of Raltegravir published last year found it to be effective in patients who had been taking regular antiretroviral HIV drugs for about 10 years.
Treatment for HIV is helping people to live longer but, in the UK, one of the biggest challenges is the threat of resistance.
Integrase is one of three HIV enzymes the virus uses to multiply.
It inserts viral genes into the DNA of the host cell, effectively making it a “factory“ for producing more of the virus.
Without this, the virus cannot multiply and infect other cells as easily, reducing the amount of virus present in the blood.
Dr Mark Nelson, director of HIV services, at Chelsea and Westminster Hospital, London, said the drug would be used in a small proportion of patients as part of a combination of drugs.
“HIV is a clever virus which adapts and mutates quickly, producing drug resistant strains of the virus.
“The more ways we have to attack the virus, the more chance we have of successfully managing the disease.
“But we’ve got to be smart about how we use these new drugs - we don’t want to repeat past mistakes where resistance arose from using single therapies.“
Roger Pebody, treatment advisor at the Terrence Higgins Trust, said the drug would be useful for as many as 10% of people currently on treatment.
“This is excellent news for people who are resistant to other HIV drugs.
“A combination of drugs is used to stop HIV at different stages of the process of entering and destroying the body’s immune cells.
“If someone becomes resistant to any of their drugs, their treatment needs to be changed, and drugs which work in innovative ways can make a real difference.“
Professor David Back, an expert in pharmacology at the University of Liverpool said the drug would be “extremely useful“ in some patients.
“Patients are remaining healthy for an extended period of time and there is a percentage who will fail therapy.“
He added that, if patients became resistant to one drug within a class, they could be resistant to others within that class even if they had never taken them before.
“It provides another option.“

An artist might spend weeks fretting over questions of depth, scale and perspective in a landscape painting, but once it is done, what’s left is a two-dimensional image with a fixed point of view.
But the Make3d algorithm, developed by Stanford computer scientists, can take any two-dimensional image and create a three-dimensional “fly around“ model of its content, giving viewers access to the scene’s depth and a range of points of view, ScienceDaily wrote.
“The algorithm uses a variety of visual cues that humans use for estimating the 3-D aspects of a scene,“ said Ashutosh Saxena, a doctoral student in computer science who developed the Make3d website with Andrew Ng, an assistant professor of computer science. “If we look at a grass field, we can see that the texture changes in a particular way as it becomes more distant.“
The applications of extracting 3-D models from 2-D images, the researchers say, could range from enhanced pictures for online real estate sites to quickly creating environments for video games and improving the vision and dexterity of mobile robots as they navigate through the spatial world.
Extracting 3-D information from still images is an emerging class of technology. In the past, some researchers have synthesized 3-D models by analyzing multiple images of a scene. Others, including Ng and Saxena in 2005, have developed algorithms that infer depth from single images by combining assumptions about what must be ground or sky with simple cues such as vertical lines in the image that represent walls or trees.
But Make3d creates accurate and smooth models about twice as often as competing approaches, Ng said, by abandoning limiting assumptions in favor of a new, deeper analysis of each image and the powerful artificial intelligence technique “machine learning.“
To ’teach’ the algorithm about depth, orientation and position in 2-D images, the researchers fed it still images of campus scenes along with 3-D data of the same scenes gathered with laser scanners.
The algorithm correlated the two sets together, eventually gaining a good idea of the trends and patterns associated with being near or far.
For example, it learned that abrupt changes along edges correlate well with one object occluding another, and it saw that things that are far away can be just a little hazier and more bluish than things that are close.
To make these judgments, the algorithm breaks the image up into tiny planes called ’superpixels,’ which are within the image and have very uniform color, brightness and other attributes. By looking at a superpixel in concert with its neighbors, analyzing changes such as gradations of texture, the algorithm makes a judgment about how far it is from the viewer and what its orientation in space is.

Scientists have deciphered the complex cocktail of digestive and antibacterial enzymes of the carnivorous pitcher plant.

Splash! Ooch! Yum! And so another unsuspecting insect victim of Nepenthes alata (N. alata), commonly known as the carnivorous pitcher plant, falls victim to the digestive fluids at the bottom of the plant’s famous cup-shaped leaf. For almost a century, scientists have sought the full chemical recipe for the pitcher plant’s fluid.
Japanese scientists now report completely deciphering this complex cocktail of digestive and antibacterial enzymes. Their study is scheduled for the February issue of ACS’ Journal of Proteome Research, Physorg.com reported.
Unlike other plants that absorb nutrients from the soil, carnivorous plants growing in nutrient-poor soils have special organs to capture insects, digest them and absorb the nitrogen and phosphorous their environment sorely lacks.
The identity of all the myriad proteins involved in this evolutionary marvel--some of which could have beneficial applications in medicine and agriculture--has been a mystery until now.
Tatsuro Hamada and Naoya Hatano used cutting-edge proteomic analysis to identify all of the components. They isolated and sequenced the proteins, then compared each with existing proteins to find structural matches.
Hamada and Hatano detected seven proteins that exist mainly in the pitcher fluid of N. alata--three of which can only be found in this species--including useful enzymes that may inhibit bacterial growth and rotting as the plant slowly digests its prey.