Thursday 1-27-05
Waterier water cleans cleaner
Taking dissolved gases out of water by pumping it through a porous membrane makes for a chemical-free grease cleaner. The surface tension of the bubbles ordinarily present in water blocks cleaning action by acting like glue. Research paper. News story from Nature magazine.
Beady protection
Want to make sure your hands-free cellphone headset is not acting as a conduit for electromagnetic radiation? The chairman of the British Mobile Telecommunications and Health Research Program has pointed out that all it takes to block the radiation is a small ferromagnetic ceramic bead attached to the headset wire. Cost -- a few cents.
Friday 1-21-05
Fast flap
Cross off the question of how insects can flap their wings faster than the speed of a nerve impulse from the list of natural mysteries. Researchers working with tethered fruit flies and high-energy x-ray beams have discovered how a spring-like muscle structure works at the molecular level. The researchers' x-ray movies captured the motion of the molecules responsible for the fast, cyclic flapping motion, showing that the muscles efficiently transfer energy from one stroke to the next. It takes just five thousandths of a second for a fruit fly to flap its wings up and down -- that's 200 cycles a second. This is much faster than the crankshaft of a car engine, which revolves 50 to 65 times a second, or the propeller of outboard boat motor, which revolves 75 to 90 times a second. (fruitfly portrait)
Tuesday 1-18-05
Cell signaling subtleties
Life is complicated. Timing is everything. These are true, it seems, on the cellular as well as the social level. It is clear that cells communicate using several types of signals. The details, however, have always been murky. Researchers have found that cells use patterns of signals to switch genes on and off, and key to interpreting a signal is its timing. It looks like signal meaning depends on signal number, duration and amplitude.
Thursday 1-13-05
Cell phone caution
The UK National Radiological Protection Board (NRPB) has issued a cautionary report about mobile phone use, pointing to Dutch, German, Swedish and EU studies that show some cause for concern.
The report stressed that although hard evidence of adverse health effects on the general public is lacking, there has not been enough research for a good judgment on the matter, especially concerning long-term exposure and the exposure of children and others who are potentially more sensitive to the radiofrequency waves emitted by cell phones.
Citing the uncertainties, the board recommended a precautionary approach for all involved, including government, the mobile phone industry, and mobile phone users.
Worldwide, mobile phone use has doubled since 2000. Nearly 1.5 billion people, about a quarter of the world's population, use mobile phones, according to the International Telecommunication Union. There are more Chinese mobile phone users than people in the U.S.
There are two major standards for mobile phones: Code Division Multiple Access (CDMA) and Global System for Mobile Communication (GSM). The U.S.-based CDMA operates at frequencies of 800 or 1900 megahertz, and the international GSM operates at frequencies of 900, 1800 or 1900 megahertz. The systems are incompatible.
Monday 1-10-05
What rats hear when we speak
Researchers have added a third animal to the list that can tell human languages apart through recognizing different speech patterns. Joining humans and monkeys in this test of intelligence are rats. Previous research showed that tamarin monkeys share the trait with humans. There may be other species that recognize more than we think in human speech.
The good news about the rats is that although they pick up enough information from the rhythm and intonation of speech to differentiate Dutch from Japanese, they are not nearly as good at this as humans. They found it difficult to tell the languages apart when the researchers threw them a curveball by having different people speak a test sentence rather than using a standard synthesized voice. Also reassuring is the researchers postulation that the rats' ability to tell languages apart is a byproduct of a rat ability that has nothing to do with listening in on humans -- the ability to detect the time order of events through hearing.
Friday 1-7-05
Geckos and lint
Geckos have taken the utility of stickiness very far -- their toes stick to nearly any surface strongly enough that a gecko can hang by a single toe. The adhesive effect is carried off by millions of microscopic hairs. One key to using adhesive surfaces successfully is keeping them clean. Geckos were a bit of a mystery in this regard, because they do not groom their feet. Researchers have found that gecko feet are self-cleaning, shedding any dirt within a few steps because the attraction between dirt and the tiny hairs is less than the attraction between dirt and the surface. The researchers have fashioned a self-cleaning adhesive that is also appropriate for outer space use based on the knowledge they gained from gecko feet.
Tuesday 1-4-05
How the South Pole froze over
Atmospheric levels of carbon dioxide are not only a key factor in the future of the ice sheets that cover the Antarctic, but could also have played a major role in the ice sheets' quick formation 32 million years ago. Researchers at Purdue University have found evidence refuting the reigning view that Antarctica froze over when a warm ocean current was interrupted by continental drift. The researchers showed that the warm current didn't reach Antarctica even before the continental shift, and said that in light of the new data, the most likely trigger for the ice caps was a change in carbon dioxide levels. The atmospheric feedback mechanisms triggered by a change in carbon dioxide levels from very high to relatively low could have caused a mile of ice to form over the continent within a relatively brief period of a few tens of thousands of years. A 2003 UMass simulation showed that a shift in carbon dioxide levels could cause an ice sheet to form.
Today's atmospheric levels of carbon dioxide are 360 parts per million. This is about 85 parts per million more than was present in the early 18th century, and is the highest level in at least 420,000 years, according to data from ice cores. Fossil fuel burning and cement production add about 6.5 gigatons of carbon to the atmosphere every year; about 3.5 gigatons are not reabsorbed and so add to the atmospheric carbon level.
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