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Feb. 20th, 2011
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Feb. 20th, 2011 12:39 pmMagnetic resonance imaging works by blasting biological tissue with a strong, uniform radiofrequency magnetic field and then listening for the weak field generated by hydrogen nuclei in response.
Various physicists have pointed out that one way of improving these devices is with lenses designed to channel and focus these fields. These lenses have become possible thanks to the development of metamaterials, periodic arrays of electronic components that together bend these fields in the desired way.
But there's a problem. Metamaterials designed to focus the weak fields generated by hydrogen nuclei can distort the much stronger field that stimulates them. Similarly, metamaterials designed for the stronger field can produce unwanted distortions in the weaker fields.
What's needed is a metamaterial that works well for both fields.
Today, Marcos Lopez at the University of Seville and a few pals reveal the solution: an adaptable metamaterial that adjusts its properties according to the fields around it.
Various physicists have pointed out that one way of improving these devices is with lenses designed to channel and focus these fields. These lenses have become possible thanks to the development of metamaterials, periodic arrays of electronic components that together bend these fields in the desired way.
But there's a problem. Metamaterials designed to focus the weak fields generated by hydrogen nuclei can distort the much stronger field that stimulates them. Similarly, metamaterials designed for the stronger field can produce unwanted distortions in the weaker fields.
What's needed is a metamaterial that works well for both fields.
Today, Marcos Lopez at the University of Seville and a few pals reveal the solution: an adaptable metamaterial that adjusts its properties according to the fields around it.
File under "R" for "rage"
Feb. 20th, 2011 12:48 pmA veteran firefighter refused to respond to last month's deadly shooting spree that left Rep. Gabrielle Giffords wounded because he had different political views than his colleagues and "did not want to be part of it," according to internal city memos.