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Scientists have known for years that simple animals – worms, flies and even rodents – live longer if they are not allowed to eat as much as they want, because their metabolism is reprogrammed to work more slowly. But controversy rages over whether human longevity would be increased by stringent calorific restriction.
Since a controlled clinical trial over a human lifetime is not practicable, researchers are studying calorific restriction in monkeys, in the expectation that such a primate study will be applicable to people. There are two main studies, both taking place in the US with rhesus monkeys, and they are giving contradictory results.
Both projects began in the late 1980s. First to report, in 2009, was a study of 76 monkeys at the University of Wisconsin. It found substantial benefits in health and longevity from calorific restriction. But in 2012, the other study, involving 120 monkeys at the National Institute on Ageing (NIA) in Maryland, reported no significant difference in health or longevity between animals on restricted and unrestricted diets.
Now the Wisconsin team has published further findings in the journal Nature Communications, confirming its original conclusions and attempting to explain why these contradict the NIA study.
The new data show that monkeys whose calorie intake was cut by 30 per cent had a threefold decrease in disease and risk of death, compared with animals on a free diet.
“Our study means the biology we have seen in lower organisms is germane to primates,” says Richard Weindruch, a professor of medicine at Wisconsin. “We continue to believe that mechanisms that combat ageing in calorific restriction will offer a lead into drugs or other treatments to slow the onset of disease and death.”
Differences in design between the two studies may account for their conflicting findings. The Wisconsin project started with adult monkeys whose food intake on a free diet was already known; the experimental diet was based on a 30 per cent reduction. In contrast, the NIA researchers fed a standardised food intake regime to both their groups – controls, and animals eating 30 per cent less.
The Wisconsin team suggest that in the NIA study even the control animals were, in effect, on a modestly restricted diet rather than eating freely. “The lack of difference between NIA controls and calorific restriction suggests that for primates there may be little advantage of [greater] calorific restriction over modest calorific restriction,” their paper says. “This would be an extremely important discovery, and one that merits further investigation.”
To that end, the two groups have begun a comprehensive analysis of their combined data.
Flat antennas could transform aircraft design
Antennas that receive and transmit radio waves have to be a particular curved shape to focus the electromagnetic waves. Now, however, scientists at BAE Systems and Queen Mary University of London have created a new type of antenna lens that can be flat, or made into whatever shape best suits its end use.
The team developed its lens by combining “composite meta-materials” (artificially engineered to do things beyond the scope of natural materials) with “transformation optics”, which provides new ways of controlling electromagnetic radiation.
An antenna made with the new technology could, for example, be embedded into the skin of an aircraft – unlike current airborne antennas, which have to be mounted within a curved radome. As Sajad Haq, project leader at BAE Systems Advanced Technology Centre in Bristol, explains: “The technology could lead us to think differently about aircraft design as well as lowering radar cross-sections and providing weight savings.”
Other possible applications include satellite television receivers built invisibly into house walls, or a mobile communications antenna woven into the uniform or helmet of a soldier or police officer.
Yang Hao, his collaborator, from Queen Mary’s, adds: “It’s possible this research could contribute to the production of even smaller or discrete antennas. This could be useful in all walks of life, from healthcare to telecommunications.”
Haq expects the first applications of the technology to appear within two to five years. BAE will include the new antennas in its own defence and aerospace products, while licensees can exploit other markets. “We have a clear world lead with this technology,” he says.
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