| Science/tech news |
[Feb. 6th, 2004|11:59 am] |
Men inflict greater [perceived] pain than women
Men and women report feeling more pain if the person inflicting the pain is male, shows a UK study.
Participants placed a finger in a clamp which was tightened using a pressure gauge until they reported feeling pain. Both men and women appeared to feel pain more quickly if the person turning the clamp was a man.
The study also shows that a person's surroundings can affect their sensitivity to pain. Objects that might be associated with suffering - such as a chart showing wounds or a poster related to blood donations - were found to make the participants report feeling pain more readily.
Williams speculates that a subjective interpretation of pain may be geared towards survival. "Heightened sensitivity would have an evolutionary benefit as it would make people more likely to take action to avoid pain and therefore more likely to leave a negative or dangerous situation," he says. "Or leave it more quickly than they would do otherwise."
The study took account of the fact that men in general appear to have a higher pain threshold than women. Participants were also asked to rate the pain they felt on a sliding scale. Subjects indicated feeling roughly the same amount of pain each time, indicating that they were not reporting it falsely.
But other experts are more guarded about the study's implications. Gary Rollman, of the University of Western Ontario in Canada, says numerous social factors may have contributed to the results. "One has to be cautious about any study of this sort in terms of generalising," he told New Scientist.
But Rollman says the study could help medical practitioners understand how they might lessen the suffering of their patients. "There may be things that all pain practitioners can learn in terms of listening to their patients and being aware of their expectation of pain and trying to reassure them," he says.
Tiny corkscrew pulls blood clots from brain
A tiny corkscrew that pulls blood clots out of the arteries supplying the brain is showing promise in reversing the devastating effects of a stroke.
Starkman's team are evaluating the new device, which is made by California-based company Concentric Medical, and it has been tested on 114 patients so far. Blood flow was restored to the affected parts of the brain in 61 patients. Of these, 23 ended up with either no disability or with only relatively minor problems, such as difficulty writing.
Most strokes are caused when a clot seals off a blood vessel supplying the brain, causing part of the brain to be starved of oxygen. Unless treated swiftly, the affected brain tissue dies, resulting in death or permanent disablement. Strokes are currently treated in two ways, both of which use "clot-busting" drugs to unblock the arteries. The most straightforward treatment involves the injection of plasminogen activator (tPA) into a main artery, which encourages the clot to dissolve.
Another approach involves guiding a catheter to the site of the clot and spraying it directly with tPA. The blood-clot can also be prodded with the catheter tip to help break it up.
But the new device aims to remove the clot completely. The spiral-tipped catheter looks like a miniature corkscrew, 2.6 millimetres wide. It is inserted into an artery in the groin and guided to the blocked blood vessel near the brain using a real-time X-ray scanner. It is then drilled into the clot, just as a corkscrew is driven into the cork of a wine bottle.
Next, a balloon is inflated immediately behind the tip of the device. This temporarily seals off the blood flow, reducing the force needed to pull out the clot.
Once it is moving, the clot is pulled back into a larger catheter and the whole device is removed from the body. The blood flow returns to the damaged part of the brain within seconds.
Starkman says the main advantage of the new device is that it does away with the need for clot-busting drugs. About six per cent of patients given such drugs suffer a brain haemorrhage. "Once the bleeding starts the patient is likely to end up either dead or disabled. It's catastrophic," he says.
Clot-busting drugs are also only effective if given within a few hours of the stroke. The patients in Starkman's trial suffered strokes at least eight hours before their treatment began.
'Mindsight' could explain sixth sense
Some people may be aware that a scene they are looking at has changed without being able to identify what that change is. This could be a newly discovered mode of conscious visual perception, according to the psychologist who discovered it. He has dubbed the phenomenon "mindsight".
Our visual system can produce a strong gut feeling that something has changed, Rensink says, even if we cannot visualise that change in our minds and cannot say what was altered or where the alteration occurred.
"I think this effect explains a lot of the belief in a sixth sense." He has no idea what physical processes generate mindsight, but says it may be possible to confirm it exists using brain scanners.
Mindsight is not simply a precursor to normal visual perception, he argues, because there seems to be no correlation between how long it takes someone to feel the change, and the time taken to identify what it is. The two sometimes happened almost simultaneously, while at other times the subjects did not report seeing any difference until seconds after they were aware of it.
Vision researcher Dan Simons of the University of Illinois in Urbana-Champaign says Rensink's finding "suggests the existence of an interesting and previously unknown attentional mechanism".
He cautions that people can sometimes believe they have perceived something when they clearly have not, pointing out that Rensink's volunteers sometimes reported seeing a change in the image when in fact it remained consistent. But he says Rensink's study is an important first step in distinguishing accurate sensing from believing.
Rensink acknowledges that not everyone seems to sense something, and that the experimental setting might encourage people to simply guess. But he also thinks that people who do not experience mindsight may be screening out what appear to be gut feelings in favour of what appears to be more rational information, while those who do are happy to trust their instincts.
Mindsight may also be at work when someone goes into a room and senses something is different but cannot put their finger on what. "It could well be an alerting system," he says. There is no reason the effect shouldn't operate with other senses too, he says. Knowing someone is behind you may be the auditory equivalent.
Cellphones safe - at least in short term
The first in a series of eagerly anticipated nationwide studies has concluded that the use of mobile phones poses no increased risk of brain cancer - at least not for the first 10 years.
Despite this caveat, the Danish study is likely to carry more weight with health authorities and scientists than many previous studies because of its large sample size and careful design. Earlier studies that claimed to find evidence of a health risk have been criticised for weaknesses in these areas.
One key aspect of the new study is that it was "population-based", i.e. the researchers attempted to recruit every new case of a rare brain tumour in Denmark's entire population of 5.3 million people over a two year period.
In total, 106 people were identified and their phone usage and medical records were then compared with those of 212 randomly chosen controls, matched for age, sex and socio-economic status. The researchers found no difference in mobile phone use between the two groups.
The tumour type studied, called an acoustic neuroma, is a rare benign tumour that forms between the brain and the inner ear. "It's located right where the radiation is most intense," Christensen told New Scientist. "If mobile phones are in some way able to influence tumour tissue, it should be able to influence acoustic neuromas."
Too few of the subjects had used phones for more than 10 years to tell if there was a long-term risk, she says. There were not just fewer people using phones back then, says her colleague Christoffer Johansen, those that had mobiles also used them much less frequently than they do today.
Nanotech spy eyes life inside the cell
A team led by Bogdan Dragnea at Indiana University in Bloomington is exploiting the ability of viruses laden with gold to break into cells, along with the viral shell's own telltale response to laser light. Together these give an unprecedented picture of the chemical and physical activity in cells.
Researchers currently study living cells using a technique called Raman spectroscopy. When laser light bounces off some materials, most of the scattered light has the same wavelength as the incident light. But a fraction called the Raman spectrum has an altered wavelength due to the characteristic vibration of some molecules in the material.
This allows researchers to map the coarser features of a cell, such as its nucleus. But Raman spectra are very weak. Introducing gold nanoparticles into cells enhances the Raman signal more than fivefold, because electrons on the surface of the nanoparticle interact with and reinforce the scattered light.
Unfortunately, the cell treats gold nanoparticles as foreign bodies and quickly clears them out. But viruses are already able to avoid ejection. So Dragnea and his team decided to use them as Trojan horses to smuggle the particles into living cells.
Viral shell
To get the gold inside a virus, the researchers took a pathogen that infects barley, called the brome mosaic virus, and put it in an alkaline solution. This breaks down the viral shell into its constituent amino acids.
Then they allowed the virus to reassemble itself by lowering the solution's pH. When this was done in the presence of gold nanoparticles just five nanometres in diameter, many of the reassembled shells had gold instead of viral RNA inside them.
"This allows us to see a single virus at a time [under the microscope]," says Dragnea. Until now, biologists have mainly studied populations of viruses. Dragnea now plans to try the technique on a barley plant cell.
If it works, virologist Lynn Enquist of Princeton University says it will be a breakthrough. "The only way we could look at individual viruses was in fixed preparations, using electron microscopy," he says. "Imaging individual viruses in living cells is powerful technology."
The virus can also map the cell's chemistry, because Raman signals vary depending on the pH or ionic strength of the virus's environment. The maps will have an astonishing resolution of about 30 nanometres - the diameter of the virus.
Smart cellphone antennas boost coverage
Smart cellphone antennas that reduce the number of masts needed to get the new 3G broadband mobile networks up and running - and minimise "dead" spots in phone coverage to boot - will be tested on a novel network during the Olympic Games in Athens this summer.
Queen Mary's new system allows antennas in any wireless network to communicate automatically and divert their resources to where they are needed most. "You can free up capacity without putting in more base stations, by simply making base stations more flexible," Cuthbert says
Gene-altered mouse produces fish oils
Fish oils known to help prevent heart attacks can now be made by land animals for themselves, thanks to work by genetic engineers.
The researchers inserted a gene from a nematode worm into mice which enables the mammals to make the omega-3 fatty acids. If the same feat can be achieved in farm animals, meat, milk and eggs could all be directly enriched with the oils.
Kang gave the mice a gene called fat-1, taken from the nematode Caenorhabditis elegans. The gene makes omega-3 fatty acid saturase, an enzyme which converts omega-6 fatty acids into their omega-3 counterparts, and humans and other animals already make the omega-6 oils
As well as protecting hearts, omega-3 oils improve circulation, are thought to dampen inflammatory conditions and could even combat cancer. Fish such as mackerel, salmon and herring naturally contain omega-3 oils, but many people do not eat the recommended amount. Other foods and supplements containing the oils are available, but are expensive.
"The US market might be more tolerant, but the practicalities of getting people to eat GM farm animals are extremely problematic, especially in Europe," says Lund, who is investigating whether omega-3 oils can prevent colon cancer in rats.
But Kang says the project is moving forward: "We're first going to do it in chickens.
Smog-busting paint soaks up noxious gases
A paint that soaks up some of the most noxious gases from vehicle exhausts will goes on sale in Europe in March. Its makers hope it will give architects and town planners a new weapon in the fight against pollution.
Called Ecopaint, the substance is designed to reduce levels of the nitrogen oxides, collectively known as the NOx gases, which cause respiratory problems and trigger smog production.
Patents filed last week show how the novel coating works. The paint's base is polysiloxane, a silicon-based polymer. Embedded in it are spherical nanoparticles of titanium dioxide and calcium carbonate 30 nanometres wide. Because the particles are so small, the paint is clear, but pigment can be added. The first paint to go on sale will be white.
Paint reaction
Paint reaction
The polysiloxane base is porous enough to allow NOx to diffuse though it and adhere to the titanium dioxide particles. The particles absorb ultraviolet radiation in sunlight and use this energy to convert NOx to nitric acid.
The acid is then either washed away in rain, or neutralised by the alkaline calcium carbonate particles, producing harmless quantities of carbon dioxide, water and calcium nitrate, which will also wash away.
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