The star designated as GK Per outbursts once in three years, but the exact moment cannot be predicted, Sobotka noted.

Astronomers observed the first distinct brightening up of the star 105 years ago. The star was then visible easily even without a binocular.

The outburst of the star this year was first discovered by an amateur astronomer Lubos Brat a few days ago.

As the process continued next night as well, Brat informed his colleagues from the Astronomical Institute, which confirmed his discovery.

"Because this analysis was both more inclusive and more conservative than previous reviews, we have the best evidence to date that these interventions are helpful," said psychologist and review lead author Robert Kerns of the VA Connecticut Healthcare System.

The trials included adults with nonmalignant low back pain lasting at least three months, with an average duration of 7.5 years.

The approaches included self-regulatory treatments, such as hypnosis and relaxation, and supportive counselling.

The largest and most consistent effect was a reduction in pain intensity, the researchers found.

When the interventions were first developed, the goal was actually to help patients to live with their pain more successfully, not reduce it.

No psychological treatment offers a cure for people with chronic pain, but people may be expecting it, said Dennis Turk, a professor of anesthesiology and pain research at the University of Washington in Seattle.

The psychological interventions are cheaper than other treatments such as surgery and opioids, he said.

"The paradox is that, despite data on the effectiveness of psychological interventions, insurers are less willing to pay for them."

A laboratory test confirmed he had the disease.

Three dozen hospital employees and one other patient tested positive for whooping cough from late September through early November.

But further testing, different from the initial tests, could find little evidence of the highly contagious bacteria. Now no one can say for sure what made the workers sick, but pertussis hasn't been ruled out.

Federal and state health officials joined the city in trying to figure out exactly what ailed the workers, all of whom recovered.

The Children's Hospital cases were at first confirmed through a test called polymerase chain reaction, or PCR.

Based on the tests, Children's moved to contain the outbreak.

"Children's, much like we do at the local health department, really relies on laboratory tests to guide us on what the diagnosis is, especially illnesses that can look like a lot of different things," said Dr. Anita Barry of the Boston Public Health Commission. "Having accurate test results early on, particularly when they're consistent with the clinical symptoms, really launches us into control steps."

State lab workers then performed other tests, including the laborious task of culturing samples and taking blood samples from hospital workers.

The additional tests were almost uniformly negative for pertussis.

Samples were sent to the federal Centers for Disease Control.

"The results were inconclusive," said Dr. Amanda Cohn, a medical epidemiologist for the federal agency.

There are competing theories, ranging from a cold virus to a bacterial relative of pertussis to the virus that causes the condition commonly known as walking pneumonia.

It's unlikely that the causes of all the respiratory illnesses will ever be fully known.

"What I can say is that whatever it was, it went away," Barry said. "And that's the good news."

Barzilai and his colleagues had found that centenarians were much more likely than others to have the gene variant, called CETP VV. People with the gene variant seemed to age slowly and were able to resist life-shortening ailments such as heart disease.

To see whether the gene protected the brain too, the team studied 158 people of Ashkenazi (Eastern European) Jewish descent who were 95 or older. A brain function test found that seniors who had inherited the gene variant were twice as likely to have good brain function - able to think clearly and remember new information - as seniors without the gene.

To see whether the gene protected against Alzheimer's, the team did a second study. A group of 124 Ashkenazi Jews ages 75 to 85 were followed for about eight years. Researchers noted any time a senior received a diagnosis of dementia. Participants who never developed dementia were five times more likely to have the favorable gene than those who did have dementia.

The researchers don't know yet how the supergene protects people. Previous research has shown that the gene could affect the size of the lipoproteins in the blood that deposit or clear away cholesterol. People with the gene variant tend to be at less risk of clogged arteries, Barzilai says.

The gene might protect the brain the same way. William Thies at the Chicago-based Alzheimer's Association says people with wide-open arteries are more likely to be getting a good blood flow to the brain and that might help seniors maintain a mental edge.

The lucky people who inherit the gene variant can do all the wrong things and still live to be 100, Barzilai says. "I had people in the study who had smoked for 90 years."

These fossils belong to the group of dinosaurs called Sauropoda, which had long necks and tails and weighed some 50 tons with a length of about 118 feet.

The scientists have named this new European dinosaur (gender and species) Turiasaurus riodevensis, having bone structure and extremities less evolved than the species known until now in the Jurassic-Cretaceous periods.

Stanford University scientists, writing in Nature, say the behaviour of a single protein determines what happens.

Toxoplasma is particularly dangerous for people with weakened immune systems, such as those with HIV, and for women in the first three months of pregnancy, as it can cause severe birth defects.

Its normal lifecycle starts in cats. It is then passed, usually via the cat's faeces, to rats and then back to cats when they catch and eat the infected rats.

Humans can become infected either when they come into contact with cat faeces, or by eating undercooked mutton, as sheep can also become carriers.

Successful invader

The Stanford researchers are interested in the ability of Toxoplasma to adapt genetically to a wide variety of hosts.

Their study reveals how the parasite injects a single protein into a cell it wants to invade, and how this protein makes its way to the nucleus of the cell and interferes with the ability of the cell to trigger an immune defence.

Susan Coller, one of the researchers leading the project, said that the strategy was very effective: "The nucleus is the heart of the cell, the ultimate prize. If you want to affect the cell in a dramatic way, go straight there."

The other finding was subtle differences in this key protein between different types of Toxoplasma - each different strain perhaps tailored to infecting different types of host cell with the minimum damage.

Severe toxoplasmosis may happen when the "wrong" strain, one not suited to infecting humans, tries to invade our cells with the protein either too powerful - overwhelming and destroying them, or ineffective - triggering a massive immune system response.

Screening test

They suggest that their discoveries about how Toxoplasma is so successful could also apply to our parasite invaders - such as malaria.

Professor John Barrett, a senior lecturer in parasitology at the University of Aberystwyth, said that there were arguments for screening pregnant women for Toxoplasma to avoid birth defects.

"The effect on the foetus can be very serious and there is a reliable test for Toxoplasma, so in these higher risk groups, it may be worthwhile."