Scientific American Online

Edit or's note: In light of the recent death of Martin Gardner, we are republishing this article from the August 1998 issue of Scientific American. Gardner wrote the "Mathematical Games" column for Scientific American from 1956 to 1981, and continued to contribute columns on an occasional basis for several years afterward . This article, which includes four puzzles by Martin Gardner, was his final piece for the magazine.

My “Mathematical Games” column began in the December 1956 issue of Scientific American with an article on hexaflexagons. These curious structures, created by folding an ordinary strip of paper into a hexagon and then gluing the ends together, could be turned inside out repeatedly, revealing one or more hidden faces. The structures were invented in 1939 by a group of Princeton University graduate students. Hexaflexagons are fun to play with, but more important, they show the link between recreational puzzles and “serious” mathematics: one of their inventors was Richard Feynman, who went on to become one of the most famous theoretical physicists of the century. [More]

Can aquatic snails better remember lessons learned when they are hopped up on methamphetamine? Barbara Sorg of Washington State University in Pullman teamed up with Ken Lukowiak of the University of Calgary Medicine to see if working with snails might provide clues as to why drug memories are so strong that they seem to draw addicts back into repetitive use and addiction . [More]

Numerous recent studies have undercut the purported benefits of various herbal supplements. Gingko , echinacea and Saint John's wort , have all been found relatively ineffective against many of the ills they have been claimed to help. [More]

By Eric Hand

Did a large, icy comet smash into Neptune two centuries ago? That's the picture that is emerging from the latest measurements of gases in the atmosphere of the giant blue planet.

At a meeting this week of the American Astronomical Society in Miami, Fla., Paul Hartogh, project scientist for the Herschel mission, the European Space Agency's infrared observatory satellite, described the mission's first results for the Solar System. [More]

Back in the days when better living through chemistry was a promise, not a bitter irony, nylon stockings replaced silk, refrigerators edged out iceboxes, and Americans became increasingly dependent on man-made materials. Today nearly everything we touch--clothing, furniture, carpeting, cabinets, lightbulbs, paper, toothpaste, baby teethers, iPhones , you name it--is synthetic. The harmful side effects of industrialization--smoggy air, Superfund sites, mercury-tainted fish, and on and on--have often seemed a necessary trade-off.

Three years ago, the allure of the lemur brought Meredith Barrett to Madagascar.

The Duke University doctoral student was fascinated by the island, one of the world's most threatened biodiversity hot spots, and wanted to look at the impact of human development on the endangered primates that reside there.

Sprawling blooms of cyanobacteria have swathed the surfaces of lakes and oceans around the world for billions of years. But the serene, blue-green algae may be leaching a neurotoxin into the aquatic food chain, according to a study published May 3 in Proceedings of the National Academy of Sciences ( PNAS ). The report revived a nearly 50-year-old debate over the role, if any, of the toxin in the process of neurodegeneration.

Some interesting electrical activity in the clouds of ash drifting around Europe as a result of that Icelandic volcano. Models predicted that electrical charge should be limited to the top and bottom of any ash plume, which is often the site of spectacular lightning.

But info obtained by a weather balloon found significant electrical charge within the plume. And that such charge was being generated within the plume--it wasn’t a remnant of the energy of the volcanic eruption or a result of any local weather events. Interactions among ash particles seem to be constantly renewing the charge.

By Rob Taylor

CANBERRA (Reuters) - Australia's government on Friday announced plans for legal action against Japan to stop Southern Ocean scientific whaling, but said it did not expect retaliation from its second-biggest trading partner.

Never mind your dentist. Your cardiologist might want you to brush your teeth more often. [More]

After a 16-hour pause to evaluate the effects of the " top kill " operation, BP plans to start pumping mud again this evening in an attempt to staunch the flow of oil from the MC 252 well in the Gulf of Mexico. In the meantime, "the well continues to flow," said BP chief operating officer Doug Suttles during a press briefing on May 27 . "We have not yet stopped the flow so the operation has not yet achieved its objective." [More]

BP's "top kill" effort has halted the flow of oil from the Mississippi Canyon 252 well, according to U.S. Coast Guard Admiral Thad Allen, national incident commander for the oil spill response. BP has yet to comment, however, noting only that "there are no significant events to report at this time," according to a statement on its Web site .

A set of descriptions last year of a 4.4-million-year-old hominid dubbed Ardipithecus ramidus pegged the primate as a human ancestor that lived in ancient African woodlands. [More]

By Chris Baltimore

HOUSTON (Reuters) - The amount of oil spilled by BP Plc's blown-out Gulf of Mexico well has eclipsed the 1989 Exxon Valdez disaster, and could be flowing at a rate nearly four times BP's recent estimates, according to findings of a U.S. government expert panel released on Thursday.

MIAMI--A satellite launched by NASA in 2009 to map the sky in infrared wavelengths is beginning to deliver on one of its ancillary promises, the mission's scientific leader said here at the semiannual meeting of the American Astronomical Society. Edward Wright , a University of California, Los Angeles, astronomer who serves as principal investigator for the Wide-field Infrared Survey Explorer (WISE), said in a talk Monday that the spacecraft has already discovered at least two cool, substellar objects known as brown dwarfs. [More]

Lorises, tiny nocturnal primates found in southern Asia, are increasingly at risk due to illegal wildlife trade and their use in traditional Asian medicine, a new study finds.

Every year, according to research published in the American Journal of Primatology , thousands of lorises are caught for use in traditional medicine. In countries like Cambodia it is believed that eating loris flesh can treat leprosy. Tonics made from lorises are marketed as a treatment to heal wounds and broken bones or to help women regain strength after childbirth. In Sri Lanka loris body parts are used to ward off the "evil eye" or to cast curses. Loris tears are also an ingredient in love potions.

A strain of mutant mice groom compulsively til they seriously injure themselves. The condition is considered a good animal model for OCD, and it’s similar to the human disorder trichotillomania, where people pull out their own hair. Now researchers have successfully treated this pathological behavior in the mice--with a bone marrow transplant. The work, led by Nobel Laureate Mario Capecchi, was published in the journal Cell . [ http://bit.ly/a4znGN ] [More]

By Christopher Doering