Nature: Transistors are the basic element of modern electronics. The devices serve as basic on/off logic gates controlled by a small amount of voltage. They are reliable, but maintaining the voltage consumes power. What’s more, because transistors must be hardwired, they require dedicated circuitry. A team of researchers led by Sungjung Joo of the Korea Institute of Science and Technology in Seoul, South Korea, has now created a magnetically controlled transistor that may overcome many of the drawbacks of traditional transistors. The team created a two-layer bridge out of the semiconductor indium antimonide. The top layer is filled with electrons and the lower layer is covered by positively charged “holes.” Depending on the direction of a magnetic field applied perpendicular to the bridge, electrons either flow through the upper layer or are forced into the holes in the lower layer. The ability to direct the magnetic field can be used to enable or disable sections of circuitry and thus “reprogram” the overall circuit to perform different functions. Although such transistors would be useful in any number of technologies, indium antimonide is difficult to incorporate into standard circuit manufacturing processes.
BBC: To estimate the mass of a black hole, astronomers look at the movement of the stars or plasma around it. But the method is time-consuming and inaccurate because of the random motions of the bodies being measured. Timothy Davis of the European Southern Observatory and his colleagues have developed a new technique that uses images of microwave radiation emitted by cold clouds of carbon monoxide gas. Because the gas is cold, the random, thermal motions are less vigorous, resulting in less blurring of the images. And because the images are in the microwave part of the spectrum, they are at higher resolution than previous measurements in the radio. Davis’s team used California’s Combined Array for Research in Millimeter-wave Astronomy to map the movements of particles at various distances from a black hole in NGC 4526. The researchers calculated the black hole to have a mass 450 million times the mass of our sun. Davis believes that the next generation of microwave telescopes will provide even clearer measurements and will significantly reduce the time it takes to make similar calculations.
New Scientist: To the ever-expanding field of video gaming, researchers in Germany have added a new twist: electrical muscle stimulation (EMS). Using two small wired electrodes attached to the gamer’s forearm, EMS sends strong, painless contractions to the hands. The user reflexively fights the contraction, which makes him or her feel more a part of the action. Such haptic technology, which provides tactile feedback to the user, has been likened to the visual enhancement of computer graphics. The mobile force-feedback device will be demonstrated at the Conference on Human Factors in Computing Systems in Paris in April.
Science: Although ibirds and other animals have been known for some time to use low-frequency background noise, or infrasound, to get around, until recently no one knew exactly how it worked. Infrasound can be generated either from natural events, such as deep ocean waves or earthquakes, or from human-made events, such as the acceleration of a supersonic plane. The low-level sound waves created by these events travel long distances and reverberate off the land and the atmosphere. To try to understand how birds can use the sound waves to orient themselves, Jonathan Hagstrum of the US Geological Survey studied data on homing pigeons from three sites near Ithaca, New York, where researchers at Cornell University had conducted extensive releases between 1968 and 1987. Birds released from the Jersey Hill site almost always got lost, whereas birds released from the other two sites did not. Hagstrum concluded that Jersey Hill’s terrain interrupted sound transmission. He also found that short-term atmospheric conditions—a temperature inversion, for example—can temporarily affect infrasound transmittal in an area and thus interfere with animals’ ability to find their way.