CHAMPAIGN, Ill. — In one University of Illinois lab, invisibility is a matter of now you hear it, now you don’t.
Led by mechanical science and engineering professor Nicholas Fang, Illinois researchers have demonstrated an acoustic cloak, a…
PROVIDENCE, R.I. [Brown University] — A pipefitter knows how to make an exact cut on a metal rod. But it’s far harder to imagine getting a precise cut on a carbon nanotube, with a diameter 1/50,000th the thickness of a human hair.
In a pape…
The slightest turn of the head can significantly change the way a person or animal detects sound. A subtle tilt alters the angle at which high-frequency sound waves hit the ear, providing cues to localize the sound. To use those cues, the brain must put what it hears into the context of the position of the head. Until recently, scientists were not sure how this was done. Now researchers in Wisconsin appear to have the explanation. They have discovered that in the cochlear nucleus, the first sound-processing station in the brain, certain cells accomplish the job by integrating the two kinds of information, each of which travels along a distinct pathway.
High-power ultrasound, currently used for cell disruption, particle size reduction, welding and vaporization, has been shown to be 99.99 percent effective in killing bacterial spores after only 30 seconds of non-contact exposure in experiments. In the experiments, bacterial spores contained in a paper envelope, were placed slightly (3mm) above the active area of a specially equipped source of inaudible, high frequency (70 to 200 kHz) sound waves and hit for 30 seconds. There was no contact medium, such as water or gel, between the ultrasound source and the spores as is typically used in low-power, medical diagnostic ultrasound. The experiments mark the first time that Non-Contact Ultrasound (NCU) has been shown to inactivate bacterial spores.
Submarines should have improved ability to detect undersea explosive mines thanks to advancement of a type of sonar that uses a relatively small antenna to mimic a much larger one. The technology bounces sound waves off of the sea floor, one small patch at a time. Onboard processors then combine these individual glimpses to create a larger image of the area surveyed.
With scientific instruments on NASA’s Voyagers, Galileo, Cassini and more than two dozen other spacecraft, University of Iowa physicist Dr. Don Gurnett has been recording waves that course through the thin, electrically charged gas pervading the near-vacuum of outer space. Gurnett converted the recorded plasma waves into sounds, much as a receiver turns radio waves into sound waves. “I’ve got a cardboard box full of cassette tapes of sounds that I’ve collected over nearly 40 years,” he said. Gurnett’s tapes have inspired a 10-movement musical composition called “Sun Rings.” The Grammy-nominated Kronos Quartet will premiere “Rings” this month.
