Friday, May 30, 2008

Computer trained to 'read' mind images of words

May 30, 2008

WASHINGTON - A COMPUTER has been trained to 'read' people's minds by looking at scans of their brains as they thought about specific words, researchers said on Thursday.

They hope their study, published in the journal Science, might lead to better understanding of how and where the brain stores information.

This might lead to better treatments for language disorders and learning disabilities, said Mr Tom Mitchell of the Machine Learning Department at Carnegie Mellon University in Pittsburgh, who helped lead the study.

'The question we are trying to get at is one people have been thinking about for centuries, which is: How does the brain organize knowledge?' Mr Mitchell said in a telephone interview.

'It is only in the last 10 or 15 years that we have this way that we can study this question.'

Mr Mitchell's team used functional magnetic resonance imaging, a type of brain scan that can see real-time brain activity.

They calibrated the computer by having nine student volunteers think of 58 different words, while imaging their brain activity.

'We gave instructions to people where we would tell them, 'We are going to show you words and we would like you, when you see this word, to think about its properties',' Mr Mitchell said.

They imaged each of the nine people thinking about the 58 different words, to create a kind of 'average' image of a word.

'If I show you the brain images for two words, the main thing you notice is that they look pretty much alike. If you look at them for a while you might see subtle differences,' Mitchell said.

'We have the program calculate the mean brain activity over all of the words that somebody has looked at. That gives us the average when somebody thinks about a word, and then we subtract that average out from all those images,' Mr Mitchell added.

Then the test came.

'After we train on the other 58 words, we can say 'Here are two new words you have not seen, celery and airplane'.' The computer was asked to choose which brain image corresponded with which word.

The computer passed the test, predicting when a brain image was taken when a person thought about the word 'celery' and when the assigned word was 'airplane'. The next step is to study brain activity for phrases.

'If I say 'rabbit' or 'fast rabbit' or 'cuddly rabbit', those are very different ideas,' Mr Mitchell said. 'I want to basically use that as a kind of scaffolding for studying language processing in the brain.'

Mr Mitchell was surprised at how similar brain activity was among the nine volunteers, although the work was painstaking.

For an MRI to work well, the patient must sit or lie very still for several minutes.

'It can be hard to focus,' Mr Mitchell said. 'Somewhere in the middle of that their stomach growls. And all of sudden they think, 'I'm hungry - oops.' It's not a controllable experiment.' -- REUTERS

[comment: If this works, it may be a better basis for a universal translator.]

Who needs sex when you can steal DNA?

WASHINGTON - TINY freshwater organisms that have amazed scientists because of their sex-free lifestyle may have survived so well because they steal genes from other creatures, scientists reported on Thursday.

They found genes from bacteria, fungi and even plants incorporated into the DNA of bdelloid rotifers - minuscule animals that appear to have given up sex 40 million years ago.

'Bdelloid rotifers are small freshwater invertebrates that apparently lack sexual reproduction and can withstand desiccation at any life stage,' Dr Irina Arkhipova and Dr Matthew Meselson of Harvard University in Cambridge, Massachusetts and colleagues wrote in a report in the journal Science.

They spring back into action after being dried out and also resist radiation.

Their resilience is surprising, given that sex is used by an overwhelming majority of life forms to cope with changing circumstances, by allowing organisms to get useful new genes and ditch harmful, mutated ones.

The translucent, waterborne creatures, which range in size from 0.1 mm to 1 mm, lay eggs, but all their offspring are female. So Dr Meselson's team looked at their DNA to see how they manage to survive.

Evidently, they steal.

'In bdelloid rotifers we found many genes that appear to have originated in bacteria, fungi, and plants,' they wrote.

'These fascinating animals not only have relaxed the barriers to incorporation of foreign genetic material, but, more surprisingly, they even managed to keep some of these alien genes functional,' Dr Arkhipova said in a statement.

Understanding how the animals acquire and make use of these new genes could have implications for medicine. Genetic mutations, which occur constantly in any living organism, underlie cancer, heart disease and various other diseases. -- REUTERS

Japanese man finds woman living in his closet

30 May 2008

TOKYO - A JAPANESE man puzzled by food mysteriously disappearing from his refrigerator got a shock when he found out a woman had been living in his home for months without permission, police said.

The 57-year-old man living alone - or so he thought - in the western city of Fukuoka installed a security camera and called the police when he saw images of someone walking around his home while he was out.

'We searched the house in the man's presence. We found the woman in the closet,' said a local police spokesman onFriday.

The woman, named as 58-year-old Tatsuko Horikawa, was found in a flat storage space only just big enough for a person to squeeze into lying down.

She had sneaked a mattress and several plastic bottles into the cubby hole, police said, adding that the women had been arrested.

'She told police that she had nowhere to live,' the spokesman said. 'She seems to have lived there for about a year, but not all the time.'

It is unclear how she managed to enter the home undetected. Police suspect she might have been closet-hopping, moving from house to house. -- AFP

Monday, May 12, 2008

Tin Disease

Did tin disease contribute to Napoleon's defeat in Russia? — Mike Z

This idea has been around a while but gained new oomph with the 2003 publication of the science-history book Napoleon's Buttons, by Penny Le Couteur and Jay Burreson. The story says the army Napoleon led into Russia in June 1812 had been outfitted, possibly as a cost-cutting measure, with uniforms held closed by tin buttons. When temperatures dropped during the French retreat later that year, the buttons crumbled, leaving troops exposed to the murderous elements.

Why would this happen? Well, stuff that's made mostly of tin is susceptible when subjected to cold to what's known as tin disease or tin pest, which causes regular metallic tin (also called white tin) to become gray, powdery, and brittle; when gray tin comes into contact with previously uncontaminated white tin, the condition can spread like a fungus. This change in the bonding structure of tin atoms starts very slowly at 13.2 degrees Celsius (56 degrees Fahrenheit) and speeds up as the temperature decreases, reaching a peak between -30 and -40°C.

So tin disease is real, but is the buttons story true? (Don't ask Le Couteur and Burreson, who are pretty terse and noncommittal on the topic considering it's the name of their book and all.) Me, I'd say probably not. Consider: (1) Tests performed with tin ingots suggest it'd take maybe 18 months at lowered temperatures to result in appreciable flaking. Napoleon's Russian campaign lasted less than half that long and didn't encounter severe cold until the very end. (2) It's not like tin disease was a big secret in 1812; it had been observed for centuries. Tin alloys like pewter were commonly used for buttons, and alloying tin with just 5 percent lead is enough to keep the problem at bay. (3) A mass grave of Napoleon's soldiers was discovered in Vilnius, Lithuania, in 2002. Helping to identify the 2,000-odd bodies as casualties of the hellish 1812 retreat were numerous regimental buttons, many made of tin alloy and still legible after 190 years in the ground.

You also sometimes see tin disease blamed for the failure of Robert Scott's South Pole expedition in 1912; the idea here is that tin solder used on kerosene cans deteriorated, allowing precious heating fuel to leak away. Again, not impossible, but unproven.