Archive for August, 2008

Researchers Crack the Case of Why Flies Are Hard to Swat

By Eliza Strickland | August 29, 2008 7:31 pm

flyIn a match-up between an annoyed human brandishing a fly swatter and a buzzing fly, who wins? As most people know from frustrating experience, all too often the fly easily evades the human’s swat, and buzzes merrily into another region of the room. Now, using a high-speed camera, scientists have determined just how the fly makes its astoundingly effective escape.

Biologist Michael Dickinson used a video camera that shoots 5400 frames per second to record a fly’s precise motions when threatened with a swatting. The video showed that as a threatening object moved towards the fly from one direction, it shuffled its feat and positioned itself to take off in the opposite direction–all within 200 milliseconds. “They perform an elegant little ballet with their legs,” says Dickinson. “They move their legs around to reposition their bodies so that when they do jump, they will push themselves away from the looming threat” [NPR].

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CATEGORIZED UNDER: Living World

Tobacco Plants Control Pollinators by Dosing Their Nectar With Nicotine

By Eliza Strickland | August 29, 2008 12:29 pm

tobacco plant hummingbirdWhen a hummingbird or a hawk moth sups on the sweet nectar of a wild tobacco plant, they’re not just getting a tasty meal in exchange for their services in spreading the plant’s pollen. Instead, a new study shows that the nectar may be a complex chemical cocktail that simultaneously attracts and repels pollinators in order to optimize the amount of time they spend at each flower, and the attention they pay to flowers on different plants. “This paper shows just how sophisticated a plant can be in using chemistry to get what it wants,” [The Scientist] says lead researcher Ian Baldwin.

The researchers had already analyzed the chemical composition of tobacco plants’ nectar; they found that the compound benzyl acetone is the primary attractant, and that the plants “spike” their nectar with nicotine, presumably as a poisonous deterrent to insects. But in a clever experiment, the research team created genetically modified plants with different levels of these two chemicals. In greenhouse and field experiments, the scientists were surprised to find that not only did nicotine deter nectar robbers and plant nibblers, but the right dose prevented pollinators from lingering too long at any one flower, increasing the number of flowers visited [Science News].

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CATEGORIZED UNDER: Living World

As the Martian Seasons Change, NASA's Robots Press On

By Eliza Strickland | August 29, 2008 9:33 am

Martian sunriseJust as summer is giving way to autumn in the Earth’s northern hemisphere, the seasons are changing on Mars, too. Near the Martian north pole, the Mars Phoenix Lander is watching its environment grow darker and colder, bringing Phoenix a little closer the end of its mission each day. Meanwhile, in Mars’ southern hemisphere, the rovers Spirit and Opportunity have been reinvigorated with increased sunlight to power their solar panels, and are on the move once more.

Phoenix, which has conducted fascinating experiments on the planet’s soil and water ice, saw the sun dip below the horizon yesterday for the first time since it landed on May 25. NASA officials originally planned a 90-day mission for Phoenix, which would have ended operations this week, but since the lander is in excellent condition NASA extended its mission. “It’s doing fabulously,” said Barry Goldstein, NASA’s Phoenix project manager at the Jet Propulsion Laboratory in Pasadena, Calif. “But I’ve made it clear to the science team that the warranty’s over…. The vehicle is not going to tip over and die,” Goldstein said. “But we’re getting to the point where we’re going to start seeing the creaks and groans” [SPACE.com].

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CATEGORIZED UNDER: Space, Technology

Researchers Find the Lost "Garden Cities" of the Ancient Amazon

By Eliza Strickland | August 29, 2008 8:17 am

Amazon excavationAnthropologists have uncovered the remnants of a sophisticated network of settlements in the Amazon rainforest that date back to pre-Columbian days, and which challenge notions of what a complex and organized society can look like. The 28 towns and villages found thus far were tucked away in the forest and linked by roads, and may have supported as many as 50,000 people across an area slightly smaller than New Jersey. Says lead researcher Mike Heckenberger: “These are not cities, but this is urbanism, built around towns…. If we look at your average medieval town or your average Greek polis, most are about the scale of those we find in this part of the Amazon” [Reuters].

Researchers believe that these settlements were first occupied about 1,500 years ago, and say that indicates that the rainforest has been shaped by human habitation much more profoundly than previously realized. [T]he Western Amazon forest is not, strictly speaking, what could be called “virgin” forest. It is what took over after local cultures were wiped out by European settlers and their diseases and their towns and villages were left untended [New Scientist].

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CATEGORIZED UNDER: Environment, Human Origins

What Can Stop the Cane Toad's Onslaught in Australia? A Cold Snap.

By Eliza Strickland | August 28, 2008 6:45 pm

cane toadCane toads, the green and warty invasive animals that are spreading ruin throughout ecosystems in northern Australia, may not continue their relentless march southward towards the sea. According to a new study, lower temperatures in the south may stop the toads in their tracks.

Researchers coaxed the toads into hopping through a 2-meter course in a laboratory to make a so-called “cane toad Olympics,” and measured the cold-blooded creatures’ hops at different temperatures. They found that in temperatures above 80 degrees Fahrenheit, the toads could hop at a speed of over one mile per hour. But below 60 degrees Fahrenheit, they slowed to a glacial .2 miles per hour. “This means that there’s no way the toads could invade southern parts like Melbourne, Adelaide … because they wouldn’t be able to move,” said researcher Dr Michael Kearney…. The winters of southern Australia would be too cold for the cane toads to forage or spawn, he said [The Age].

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CATEGORIZED UNDER: Living World

Deep-Sea Viruses Quietly Rule a Marine Food Chain

By Eliza Strickland | August 28, 2008 4:44 pm

oceanMinuscule viruses on the sea floor have a big impact on the marine ecosystem, a new study shows. The viruses infect simple microbes, known as prokaryotes, that form one of the lowest rungs in the food chain. Usually the nutrients and carbon contained in prokaryotes are used by the larger organisms that eat them, but something very different happens when prokaryotes are infected by viruses: the viruses burst the prokaryotes open and release their carbon and nutrients into the water column [New Scientist]. When these nutrients sink down to the ocean floor they’re consumed by other microbes, which then multiply and provide more hosts for the viruses.

Researchers long ago grasped that viruses on the sea surface play a Dr.-Jekyll-and-Mr.-Hyde role, killing biomass while at the same time sustaining it. Now, though, evidence has emerged that these tiny bacterial pathogens also carry out unsung work at the ocean depths — a dark, inhospitable, nutrient-poor place that counts as last great unexplored ecosystem on the planet [AFP]. Researchers say the newly discovered role of deep sea viruses may also play a critical role in the carbon cycle, as the decaying remnants of the burst microbes carry carbon, which is sequestered in the ocean depths.

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CATEGORIZED UNDER: Environment, Living World
MORE ABOUT: ecosystems, ocean, viruses

Forget the Hearing Aid: Why Not Regrow Inner Ear Cells?

By Eliza Strickland | August 28, 2008 1:46 pm

mouse earsScientists have produced the cells that make up delicate inner ear hairs in mouse embryos, a step that could point the way to reversing hearing loss and curing congenital deafness. Sensory hair cells inside the cochlea, the auditory portion of the inner ear, convert sound waves into electrical impulses that are delivered to the brain. The loss of these minute hairs, or the nerves that control them, is the most common cause of hearing impairment and so-called nerve deafness [ABC Science].

Researchers used gene therapy to create the crucial cells: They used a virus to introduce a gene into the mice embryos, which caused non-sensory cells to turn into cochlear hair cells. While this preliminary experiment was done on normal-hearing mice, the discovery that the engineered cochlear cells functioned as well as natural cells was an important step. Says lead researcher John Brigande: “One approach to restore auditory function is to replace defective cells with healthy new cells…. Our work shows that it is possible to produce functional auditory hair cells in the mammalian cochlea” [Reuters].

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CATEGORIZED UNDER: Health & Medicine

Harnessing Quantum Weirdness to Make Spy-Proof Email

By Eliza Strickland | August 28, 2008 10:14 am

confidential filesIt may not be a big market, but it’s presumably a lucrative one: To meet the needs of consumers who are in the business of transmitting classified national secrets, physicists are working on an absolutely secure communication system that uses the strange laws of quantum mechanics to encode information. The latest experiments in this field, called quantum cryptography, produced a system that researchers say would theoretically work to transmit information around the globe.

The system relies on a concept known as quantum entanglement to establish hack-proof communication. Entanglement allows two particles to be quantum-mechanically connected even when they are physically separated. Although the specific condition of either particle cannot be precisely known, taking measurements of one will instantly tell you something about the other. The trick can’t be used to actually send information, because each particle’s condition is random until it is measured. But entanglement can be used for encrypting data if a sender and a receiver make measurements on a number of entangled particles and then compare their results [Nature News].

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CATEGORIZED UNDER: Physics & Math, Technology

Galactic Collision Gives Researchers a Glimpse of Dark Matter

By Eliza Strickland | August 28, 2008 8:30 am

dark matter cloudsThe cosmic collision of two galaxy clusters has given astronomers a clearer look at the mysterious substance known as dark matter. Researchers say when the two clusters crashed into each other, the dark matter from each cluster [appeared] to pass through the cosmic mess unscathed, leaving ordinary matter behind in the galactic pileup [SPACE.com]. Using data from NASA‘s Hubble and Chandra space telescopes, astronomers were able to produce an image showing clouds of dark matter, colored blue, on either side of the impact site.

Dark matter, mysterious stuff that exerts a gravitational force on other matter, was originally proposed to explain what holds spinning galaxies, like the Milky Way, together. Observations suggest it outweighs ordinary matter by a factor of about 6 to 1. But no one knows what it is made of, and normally dark matter and ordinary matter are too well mixed to observe the dark matter independently [New Scientist].

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CATEGORIZED UNDER: Physics & Math, Space

Beyond Stem Cells: Scientists Master Cell Transmogrification

By Eliza Strickland | August 27, 2008 7:50 pm

lab mouse 2In a discovery that’s being hailed as a leap forward in regenerative medicine, researchers have found a way to transform common pancreatic cells in an adult mouse into the rare, insulin-producing beta cells that are destroyed in type 1 diabetes. Previously, researchers believed that the only way to transmute an adult cell was to first coax it back into stem cell form and then to reprogram it; this new research removes the first step entirely.

The accomplishment raises the tantalizing prospect that patients suffering from not only diabetes but also heart disease, strokes and many other ailments could eventually have some of their cells reprogrammed to cure their afflictions without the need for drugs, transplants or other therapies. “It’s kind of an extreme makeover of a cell,” said [lead researcher] Douglas A. Melton…. “The goal is to create cells that are missing or defective in people. It’s very exciting” [Washington Post].

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CATEGORIZED UNDER: Health & Medicine
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