Science & Technology
© Unknown
Illustration only
U.S. scientists say they have detected the first direct evidence of lightning occurring on Mars. University of Michigan researchers said they found signs of electrical discharges during dust storms on the red planet. The bolts were dry lightning, Professor Chris Ruf said.
"What we saw on Mars was a series of huge and sudden electrical discharges caused by a large dust storm," Ruf said. "Clearly, there was no rain associated with the electrical discharges on Mars. However, the implied possibilities are exciting."
Electric activity in Martian dust storms has important implications for Mars science, the researchers said.
"It affects atmospheric chemistry, habitability and preparations for human exploration. It might even have implications for the origin of life, as suggested by experiments in the 1950s," said Professor Nilton Renno of the university's Department of Atmospheric, Oceanic and Space Sciences.
© Antares Amateur Astronomers Group
A Leonid meteor bursts and sputters over Italy in this false-color computer reconstruction.
Think of it as the extreme-sport version of listening for songbirds: Atmospheric scientists Douglas ReVelle, Rodney Whitaker, and Peter Brown are using microphone arrays to eavesdrop on the baritone rumblings of interplanetary rocks slamming into Earth's atmosphere.
Most of the time nobody sees them hit, but hearing them is much easier. A typical meteor arrives traveling 50 to 300 times the speed of sound, fast enough to create a powerful sonic boom and, if the object is large enough, an explosive flash. These disruptions stir up persistent low-frequency infrasound, similar to the waves from a nuclear test, which can travel thousands of miles without losing significant energy. And infrasound monitoring stations, including four arrays at Los Alamos National Laboratory and a network being built to verify the Comprehensive Test Ban Treaty, already exist to detect such waves anywhere in the world.
On April 23, 2001, scientists manning a network designed to detect covert nuclear tests noticed something unusual - a very "loud" sound coming from above the Pacific Ocean. This global network, consisting of sensitive sound-recording instruments, had picked up on a large meteor slamming into the atmosphere several hundred miles west of Baja California, and exploding with a force comparable to that of the nuclear bomb that was dropped on Hiroshima.
On Feb. 1, 2003, these same instruments heard something else - the Space Shuttle Columbia reentering Earth's atmosphere on its tragic final mission. NASA subsequently used those recordings to rule out potential causes of the mission's demise, including a bolide or missile impact.
The sensitive instruments that recorded the meteor's entrance and the end of the Columbia record a range of low-frequency sound that is inaudible to the human ear called infrasound. "It's sort of like infrared light, which is the part of the electromagnetic spectrum that we can't see, in that it's the part of the sound spectrum that we can't hear," says Michael Hedlin, a geophysicist and infrasound specialist at the University of California, San Diego, and Scripps Institution of Oceanography.
The instruments detect atmospheric noise, such as storms, winds, volcanic eruptions, ocean waves and airplane traffic, and they help scientists understand "just what's going on out there," Hedlin says. "Right now, we're just listening to the world," he says, but soon, the researchers will begin to more fully comprehend the interactions between solid earth, the oceans and the atmosphere.
Dr David Whitehouse
BBC NewsFri, 19 Jan 2001 16:06 UTC
© unknown
The burst of very-low frequency sound waves from the meteor explosion over Germany in November 1999.
Belgian scientists have detected ultra-low frequency sound waves - infrasound - from a meteor that exploded over Germany in November 1999.
They were picked up by an observatory more use to searching for the particular infrasound signatures associated with nuclear explosions. It is one of the ways scientists can monitor for compliance with test ban treaties.
This particular meteor would have exploded with a force of 1.5 kilotons of TNT, equivalent to a small nuclear weapon.
The signals were detected by the seismology division of the Royal Netherlands Meteorological Institute.
In the early darkness of April 23, as Washington was beginning to relax after the spy plane crisis in China, alarm bells began to go off on the military system that monitors the globe for nuclear blasts.
Orbiting satellites that keep watch for nuclear attack had detected a blinding flash of light over the Pacific several hundred miles southwest of Los Angeles. On the ground, shock waves were strong enough to register halfway around the world.
Tension reignited until the Pentagon could reassure official Washington that the flash was not a nuclear blast. It was a speeding meteoroid from outer space that had crashed into the earth's atmosphere, where it exploded in an intense fireball.
"There was a big flurry of activity," recalled Dr. Douglas O. ReVelle, a federal scientist who helps run the military detectors. "Events like this don't happen all the time."
Preliminary estimates, Dr. ReVelle said, are that the cosmic intruder was the third largest since the Pentagon began making global satellite observations a quarter century ago. Its explosion in the atmosphere had nearly the force of the atomic bomb dropped on Hiroshima.
© Christopher Go (Cebu, Philippines)
Astronomers are monitoring a new red spot forming in Jupiter's northern hemisphere--a brick-red storm nearly as large as the Great Red Spot itself. On June 17th, amateur astronomer Christopher Go of the Philippines photographed it using an 11-inch Celestron telescope.
"I have been monitoring the new spot since mid-April," says Go. "At first it was relatively small. In late May it began to grow rapidly, and just last week John Rogers of the British Astronomical Association issued an alert for everyone to observe it."
Oddball stellar explosion doesn't match known outbursts
Just in time for July 4, astronomers say they have found a new type of stellar firecracker.
Stars that die an explosive death generally fall into two categories: young, massive stars that collapse under their own weight and hurl their outer layers into space, and older, sun-like stars that undergo a thermonuclear explosion. But the stellar explosion recorded in January 2005 and known as SN 2005E doesn't fit either class, according to a new analysis reported online June 11 at
arXiv.org.
The explosion ejected only a small amount of material - the equivalent of 0.3 solar masses - and erupted in the halo of an isolated galaxy, a region devoid of any star formation. These findings suggest that the explosion, or supernova, did not arise from the collapse of a massive star, report study coauthors Hagai-Binyamin Perets and Avishay Gal-Yam of the Weizmann Institute of Science in Rehovot, Israel, and their colleagues. A massive star would have cast off much more material and would have erupted in a star-forming region. Since stellar heavyweights are so short-lived, they can't move far from their birth site.
A protein called neuroligin that is implicated in some forms of autism is critical to the construction of a working synapse, locking neurons together like "molecular Velcro," a study lead by a team of UC Davis researchers has found.
Published online in the June issue of the journal Neural Development, the study is accompanied by groundbreaking images that are the first to show two neurons coming together using neuroligin to construct a new synapse.
"Previous research has suggested that neuroligin is critical for the formation and stabilization of synapses," said Kimberley McAllister, an associate professor of neurology in the UC Davis School of Medicine and a researcher at the UC Davis Center for Neuroscience. "Our work suggests that neuroligin is one of the first molecules to be recruited to new synapses and that it also acts as Velcro to strengthen those new connections."
Neuroligin is a member of a family of four protein molecules that bind to another family of proteins, the β-neurexins, across synapses. During the past decade, scientists have observed that neuroligin is critical for synapse formation and function, but it is only recently that a link between the two synapse-forming molecules and autism has been recognized, McAllister said.
Victoria Gill
BBC NewsThu, 18 Jun 2009 05:26 UTC
© SPL
Humans bet for money, whereas rats gamble for food
Rats are able to play the odds in a "gambling task" designed by scientists to test the biology of addiction.
In the journal Neuropsychopharmacology, researchers describe how the rodents developed a "strategy" in a timed task where they make choices to earn treats.
The rodents avoided high-reward options because these carried high risks of punishment - their sugar pellet supply being cut off for a period.
This decision-making task provides an animal model to study neuropsychiatry.
During the task, which lasted for 30 minutes, rats were given four choices - in the form of holes to investigate.
Nosing each of these holes triggered either the delivery of tasty sugar pellets or a "punishing time-out period" during which rewards could not be earned.
But high-reward holes - those that delivered more pellets at once - also carried the bigger risk of triggering longer periods of punishment.
And rats quickly learned an "optimal strategy" - earning more pellets over the duration of the task by choosing the holes with smaller gains and smaller penalties.
In the decade since the Implicit Association Test was introduced, its most surprising and controversial finding is its indication that about 70 percent of those who took a version of the test that measures racial attitudes have an unconscious, or implicit, preference for white people compared to blacks. This contrasts with figures generally under 20 percent for self report, or survey, measures of race bias.
A new study published this week validates those findings, showing that the Implicit Association Test, a psychological tool, has validity in predicting behavior and, in particular, that it has significantly greater validity than self-reports in the socially sensitive topics of race, gender, ethnicity, sexual orientation and age.
