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Super cool atom thermometer
Posted by wideant in General Physics on March 4, 2010
As physicists strive to cool atoms down to ever more frigid temperatures, they face the daunting task of developing new, reliable ways of measuring these extreme lows. Now a team of physicists has devised a thermometer that can potentially measure temperatures as low as tens of trillionths of a degree above absolute zero. Their experiment is reported in the current issue of Physical Review Letters and highlighted with a Viewpoint in the December 7 issue of Physics.
Physicists can currently cool atoms to a few billionths of a degree, but even this is too hot for certain applications. For example, Richard Feynman dreamed of using ultracold atoms to simulate the complex quantum mechanical behavior of electrons in certain materials. This would require the atoms to be lowered to temperatures at least a hundred times colder than what has ever been achieved. Unfortunately, thermometers that can measure temperatures of a few billionths of a degree rely on physics that doesn’t apply at these extremely low temperatures. Read the rest of this entry »
Slipper-shaped blood cells
Posted by wideant in General Physics on March 4, 2010
Red blood cells, which make up 45 percent of blood, normally take the shape of circular cushions with a dimple on either side. But they can sometimes deform into an asymmetrical slipper shape. A team of physicists have used simulations to explore how fluid flow might be responsible for this deformation, as well as how the deformation in turn affects blood flow. The insights could help understand the mechanisms involved in arterial disease and other blood flow-related ailments. Their research is reported in Physical Review Letters and highlighted with a Viewpoint in the October 26 issue of Physics.
When a red blood cell flows through an artery, one face usually balloons out like a parachute, but sometimes the cell can deform to resemble a slipper. To find out why, Badr Kaoui at the Université Joseph Fourier in Grenoble, France and his colleagues modeled the cells as two-dimensional fluid-filled sacks flowing in a liquid. They found that when the cells weren’t sufficiently plump, the symmetric parachute collapsed into a slipper. They also found that this morphing helped the sacks catch up with the rest of the fluid, suggesting that the slipper shape achieves more efficient blood flow. Read the rest of this entry »
Invasive snail may damage diet of rare Everglades bird
Invasive animals often wreak havoc with their feeding habits; however, University of Florida researchers say a huge South American snail is causing problems when it’s the prey rather than the predator.
Known as the island apple snail, it could threaten an endangered bird, the Everglades snail kite. The kite normally feeds on native apple snails the size of a golf ball. But in recent years, those snails have declined in historically important kite habitat and the birds have fled.
Many kites now dwell at Central Florida’s Lake Tohopekaliga, which is filled with the invasive snails. The mollusks grow larger than a tennis ball and kites have difficulty holding them. Researchers warn that young kites there may be malnourished. Read the rest of this entry »