cover of magazine

All Fall Down

October 31, 1998 | Volume 154 | Number 18

Cover: The flutter of falling leaves has intrigued—and puzzled—generations of scientists.  Inspired anew by chaos theory, physicists in a recent spate of studies find the hallmarks of chaotic behavior as well as surprising regularities in the tumble of leaflike objects.

Features:  MathTrekspace TimeLine< /a> spaceFood for Thought spaceScience Safari

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References & SourcesClick on this icon listed by each article to get full r eferences and sources.

News of the Week:

Adult Human Brains Add New Cells

References & SourcesScientists presented the first solid evidence that nerve cells in the human brain continue to be born throughout life.



Full textCancer drug helps paralyzed mice walk

References & SourcesA bacterial toxin enables a mouse's injured spinal cord to heal.



Studies support an accelerating universe

References & SourcesNew findings support the notion that the universe will expand forever at an increasing rate.



Time proves not reversible at deepest level

References & SourcesCertain subatomic physical processes, such as the interconversion of complementary particles called kaons and antikaons, appear to take a different course if time runs in reverse.



At peace with itself, an ant triumphs

References & SourcesArgentine ants are succeeding in their march around the globe in part because they’ve stopped scrapping among themselves.



Full textGeologists anticipate an oil crisis soon

References & SourcesSeveral forecasts indicate that the supply of oil will start drying up in the near future.



Blood, semen harbor distinct HIV mutations

References & SourcesDifferent, drug-resistant populations of HIV can arise in different locations in the same infected man.



Big shocks push volcanoes over the edge

References & SourcesSome of Earth’s mightiest earthquakes have triggered volcanic explosions.

Research Notes:


Blue eyes, big earplugs: Bad hearing?

References & SourcesLight eye color and large ear-canal size may be linked to greater vulnerability to hearing loss.



Cooking up bubbles to make tiny pumps

References & SourcesSwelling and shrinking bubbles may eventually act as tiny pumps to driv e micromachines.



Sound was secret weapon in Civil War

References & SourcesBecause Civil War commanders relied on the sounds of battles to make judgments, unexpected acoustical effects may have altered the course of the war.



African dialect uses unexpected sound

References & SourcesA sound that linguists said was absent from human language turns up in a southern African dialect.



Better seal for see-through sound wall

References & SourcesResearchers have arranged rods into a new kind of sound filter that for bids a selected frequency band from passing through from any angle.



A sugar averts some ear infections

References & SourcesA natural sweetener called birch sugar helps to prevent some ear infect ions in preschoolers by thwarting Streptococcus pneumoniae bacteria.



Survival improving in organ recipients

References & SourcesAmong organ transplant recipients in the United States, survival rates improved between 1988 and 1994, especially for those receiving liver, lung, and heart-lung transplants.




Full textThe Leonids are Coming! The Leonids are Coming!

A memorable light show or just a bracing shower?

References & SourcesThis Nov. 17, Earth makes its closest approach in 33 years to Comet 55P/Tempel-Tuttle, but it isn't clear how dramatic the annual light show put on by its trail of dusty debris — the Leonid meteoroids — will prove to be.



The Puzzle of Flutter and Tumble

Physicists reconsider the fall of leaves

References & SourcesComputer simulations and chaos theory come to the fore in attempts to ex plain the motions of falling leaves and paper sheets.


Letters:      A Selection from Letters to the Editor


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