Cover; May 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)

Table of Contents; May 1998; Scientific American Magazine; by Staff Editor; 2 Page(s)

From the Editors, including Masthead; May 1998; Scientific American Magazine; by Rennie; 1 Page(s)

Letters to the Editors; May 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)

50, 100 and 150 Years Ago; May 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)

MAY 1948 FUTURE OF THE AMAZON--The Hylean (from the Greek hyle, meaning ¿wood¿) Amazon Institute is an enterprise of breathtaking scope. Its purpose is not to gouge raw material and food out of the untamed forest. The new Institute will try a more thoughtful and subtle approach. Its strategy is to study the region¿s physiography, natural history and ecology (in this case, the relationship between the environment and man) and to evolve a process whereby man will learn to live harmoniously and richly in the environment instead of fighting it. To civilize the wild, rich Amazon and open it to colonization would itself be a gigantic achievement.

COSMIC ORIGIN--The Dust Cloud Hypothesis, as it is called, suggests that planets and stars were originally formed from immense collections of submicroscopic particles floating in space. Interstellar space, formerly supposed to be empty, is now known to contain an astonishing amount of microscopic material. Jan Oort of the Netherlands, the president of the International Astronomical Union, has calculated that the total mass of this interstellar dust and gas is as great as all the material in the stars themselves, including all possible planet systems.

In Focus: Taking Aim at Tumors; May 1998; Scientific American Magazine; by Gibbs; 2 Page(s)

Atour of Lawrence Livermore National Laboratory leaves no doubt that this bastion of fundamental physics research is still obsessed with the design and safekeeping of weapons of mass destruction. In one building, a 20-meter-long (65-feet-long) gun fires projectiles at up to 29,000 kilometers (18,000 miles) an hour to simulate the impact of a ballistic missile. On the other side of campus, 10 giant lasers zap tiny pellets with 30 trillion watts to study the genesis of nuclear fusion. This is not a place one would expect to produce a significant advance in cancer therapy.

But a small team of physicists and engineers, working for five years with funding only from Livermore itself, has taken computer algorithms once used for designing nuclear weapons and assembled them into a promising new tool for treating cancer with radiation. The Peregrine system, as it is called, "is genuinely a major step forward," praises Francis J. Mahoney, head of radiotherapy development at the National Cancer Institute. The technology should be ready for installation at cancer centers sometime next year.

Making a Deep Impact; May 1998; Scientific American Magazine; by Yam; 2 Page(s)

It¿s not clear just what kind of impact Asteroid 1997 XF-11 has left on the earth. On March 11 Brian G.Marsden of the Harvard-Smithsonian Center for Astrophysics reported that in 2028, an object about 1.5 kilometers (a mile) wide would pass some 50,000 kilometers (30,000 miles) from the earth--a hair¿s breadth in astronomical terms. In fact, researchers at the time couldn¿t say for certain that the asteroid would miss the planet. The next day astronomers found photographs of the object taken in 1990 and recalculated the asteroid¿s orbit; they figured that it would miss the earth by nearly a million kilometers, more than twice the distance to the moon. A few criticized Marsden, who tabulates observations and catalogues space bodies that might hit the earth. The fear was that people might not take the next call seriously.

Some indication of public attitudes toward the threat of near-earth objects might come soon, when Hollywood releases a film this month about such a possibility. For several months, promoters of the film trained their sights on Scientific American, Sky and Telescope, the Learning Channel and other media that would not be confused with Entertainment Weekly. That¿s because Deep Impact may represent the most lavish effort yet of Hollywood¿s trying to get the science right.

In Brief; May 1998; Scientific American Magazine; by Leutwyler; 3 Page(s)

F¿s for U.S. Schools Results from the latest and most comprehensive comparison of education in 23 nations showed that American high school seniors fall further behind their foreign counterparts than anyone thought. In tests of general mathematics, students from only two nations-- Cyprus and South Africa--fared worse than U.S. 12th graders. And no country performed more poorly in tests of advanced mathematics and physics. Only those American students taking advanced placement calculus ranked higher than the average in that field.

Carbon Dioxide Crystals Up Close At last, scientists have viewed solid carbon dioxide crystals. Because these eight-sided structures typically evaporate at temperatures higher than -134 degrees Celsius (-210 degrees Fahrenheit), they had never before been seen. But William P. Wergin and his colleagues at the U.S. Agricultural Research Service found a way to glimpse the tiny crystals--measuring some 0.13 micron--by chilling them to -196 degrees C (-320 degrees F) in a special scanning electron microscope.

Snow Men; May 1998; Scientific American Magazine; by Gibbs; 2 Page(s)

March may tatter the white blanket of winter in most places, but for hydrologists Frank D. Gehrke and David M. Hart, it is the month when the snow really gets interesting. As the chief researchers overseeing California¿s snow surveys program, Gehrke and Hart must estimate the size of the great white lake draped over the mountains and alpine meadows that dominate the eastern flank of the state. Typically about 80 percent of the water that feeds California¿s inhabitants, farms and hydroelectric generators arrives in solid form and usually remains frozen until the start of the growing and air-conditioning season.

So, late each winter, the local TV camera crews strap on snowshoes and trudge out to observe Gehrke and Hart measure the snow and prognosticate on the prospects of a wet and bountiful summer. It is the West Coast version of Groundhog Day.

Water, Water Everywhere; May 1998; Scientific American Magazine; by Schneider; 3 Page(s)

In 1961, during the very month that President John F. Kennedy launched the race to the moon, Kenneth Watson, Bruce C. Murray and Harrison Brown of the California Institute of Technology noted the importance of the fact that some craters in the moon¿s polar regions are permanently in shadow. Rather than being subjected to two weeks of blistering rays from the sun each lunar month, these sites remain eternally dark and frigid. Such "cold traps," they argued, might snare water dumped on the lunar surface by crashing comets or spewed forth by lunar volcanoes. And over the aeons, inky crater floors near the poles might accumulate substantial amounts of ice. Those deposits would be immensely valuable to people on future lunar bases, who could distill water from them or separate out the oxygen and hydrogen to use as rocket propellant. It took nearly three decades, but the latest robot probe, Lunar Prospector, has seemingly con- firmed that frozen caches of water can indeed be found on the moon.

Because none of the Apollo missions visited the moon¿s poles, the proposal of Watson, Murray and Brown had remained untested for 30 years. The first experimental indication came when the Department of Defense and the National Aeronautics and Space Administration launched a probe called Clementine in 1994, with the intent of eventually flying it past a nearby asteroid. Before attempting that rendezvous, however, Clementine was sent into a polar orbit around the moon. (A software glitch later wrecked the asteroidal segment of the mission.)

Anti Gravity: Now You See It, Now You Don't; May 1998; Scientific American Magazine; by Mirsky; 1 Page(s)

Picture the Beatles in a boat on a river, with or without tangerine trees and marmalade skies. They¿re chasing another boat. Assume that Rolling Stone Keith Richards is piloting that other boat, so its path is highly erratic. The Beatles pursue, turning their boat while continuously closing the distance to their prey. Hey, it could happen.

Switching from Beatles to beetles reveals, however, that pursuit of prey in one corner of the insect world turns out to be far less smooth. As was first reported more than 70 years ago, hungry tiger beetles, which have compound if not kaleidoscope eyes, run as fast as they can toward a prospective live meal but then come to a screeching stop. During this time-out, the beetles reorient toward their sidestepping targets. After zeroing in again, they resume running as fast as they can. They may have to do this three or four times before catching their prey or giving up.

Dances of Worms; May 1998; Scientific American Magazine; by McKinsey; 1 Page(s)

Some 15 to 20 meters (49 to 66 feet) below the ocean surface, in the warm waters off the coast of Queensland, Australia, an unusual mating dance takes place among hermaphrodite flatworms--and whichever wins gets to be the male, at least for the moment. In bouts referred to as penis fencing, these marine creatures will spend 20 minutes to an hour attempting to inject sperm under the skin of their mates before being injected or injured themselves.

Most other hermaphroditic animals, such as earthworms, exchange sperm during sexual trysts. But when a lone Pseudoceros bifurcus encounters another of its kind, it will stop, curl its body back in an intimidating backbend and display its penis. Each worm, about four to six centimeters (two inches) long, will then repeatedly strike the other until one succeeds in injecting sperm, and both will maneuver themselves to avoid being pierced.

By the Numbers: The Future of the Old; May 1998; Scientific American Magazine; by Doyle; 1 Page(s)

To see the future of world population, look to Europe, where the birth rate is low and the number of elderly is rising dramatically. In Germany, for example, those 60 and older now account for 22 percent of the population and by 2025 will be at 35 percent, the majority of them women. Furthermore, because of continued low fertility, the total population of Germany is actually projected to decline by 8 percent between now and 2025.

Germany, together with other western European nations and Japan, is the advance guard of the historic demographic changes accompanying the rise of technological societies. If the global economy continues to raise living standards, developing countries will most likely follow the European model to eventual low fertility and large elderly populations. They are less likely to follow the American experience, which is atypical in part because of a continuing huge influx of immigrants. Immigrants are expected to be a major contributor to the 24 percent increase in U.S. population projected between now and 2025. In 2025 those 60 and older will account for 25 percent of the U.S. population, compared with 31 percent in western Europe.

Profile: Rebottling the Nuclear Genie; May 1998; Scientific American Magazine; by Beardsley; 2 Page(s)

Thomas B. Cochran is gazing intently at his computer screen, paging through hundreds of targets for a planned nuclear attack on Russia. The individually named and numbered strategic sites are organized by category: antiballistic-missile radars, launch-control centers, submarine docks, silo fields. Speaking quietly with a Tennessee twang, he apologizes for not yet having the exact geographical coordinates of all the missile silos--he¿s working on that. But he has the boundaries of the silo fields. And as a leading authority on nuclear weapons and official adviser to the Department of Energy, which oversees the nuclear stockpile, he also has a pretty clear idea which warheads to use against each target. "Information is extremely important in this business," he observes dryly.

Cochran is senior scientist and director of the nuclear program at the Natural Resources Defense Council, where for almost 20 years he has used aggressive political pressure tactics--information warfare of a sort--to reduce the U.S.¿s reliance on nuclear weapons. "The people on Capitol Hill aren¿t going to pay any attention to you until they read about you in the New York Times or Scientific American," he says pleasantly. "So you litigate to get publicity."

When Less is More; May 1998; Scientific American Magazine; by Randal; 2 Page(s)

In May 1996, when a bedridden Jim Absalom of Youngstown, Ohio, had just learned that a heart transplant was his only other option, two doctors at the Cleveland Clinic made him an offer he couldn¿t refuse. Cardiologist Randall C. Starling and transplant surgeon Patrick M. McCarthy had recently been to Hospital Angelina Caron in Curitiba, Brazil, to see Randas Batista perform a revolutionary operation that could give Absalom¿s own heart a new lease on life. Afraid he would die before a donor heart became available, the 65- year-old agreed to the surgery.

Absalom¿s problem was congestive heart failure, a disorder in which the left ventricle of the heart cannot pump enough blood to the rest of the body because the ventricle has gotten too large and flabby. Batista pioneered the procedure in 1983, when he was working at a hospital where transplants were not done. It is based on the premise that making the ventricle smaller by taking a wedge out of its muscular wall will improve its efficiency.

Resistance Fighting; May 1998; Scientific American Magazine; by Stix; 1 Page(s)

The soil bacterium known as Bacillus thuringiensis, or Bt, has remained the cornerstone of natural pest-control efforts for more than three decades. It¿s not hard to understand why. The bacterial toxins generally kill the bad guys (corn earworm and Colorado potato beetle, among others) and spare the good guys (humans, other mammals and beneficial insects).

But the rapidly growing acreage of corn, cotton and potatoes that are genetically engineered to produce Bt¿s pesticidal toxins highlights fears about emerging insect resistance. Genetically engineered Bt crops provide exposure to the toxins throughout the growing season, leading to selection pressures that might enable only resistant pests to survive. In contrast, Bt sprays, which are used by home gardeners and organic and other farmers, degrade quickly, making resistance less likely.

Seeing the Light; May 1998; Scientific American Magazine; by Zorpette; 2 Page(s)

One of the success stories of the electronic age is the chargecoupled device (CCD), which shows up almost everywhere an image has to be converted to electrical signals. CCDs are the electronic, infinitely reusable "film" in digital cameras and are also critical components of countless other consumer products.

Entrenched as they are, though, CCDs are about to face a major challenge. The upstart competitor is the CMOS image sensor, which has been under development for years and is finally about to take the market by storm, thanks to heavy recent investments by the likes of Eastman Kodak, Motorola, Toshiba, Intel, Rockwell and Sarnoff.

A Tongue for Love; May 1998; Scientific American Magazine; by Gibbs; 2 Page(s)

Computers, Bill Gates is fond of pointing out, lack most of the basic senses that humans often take for granted. Some advanced machines can hear and speak--poorly--but most are blind and oblivious to touch, smell and temperature. Electronic devices may soon gain a sense of taste, however, thanks to tiny electromechanical machines invented at Pennsylvania State University by husband-and-wife engineers Vijay K. and Vasundara V. Varadan. The Varadans and their collaborators presented their designs in March at a conference in San Diego.

Although the Penn State group has built only a few working prototypes of the so-called smart tongues, the Varadans predict that within a few years the devices will be cheap and sensitive enough to find myriad uses. Stuck inside milk cartons and juice bottles, some sensors might enable checkout scanners at the grocery market to detect the growth of unwanted bacteria, they suggest. Others might be placed in giant vats in food and chemical factories to monitor the blending of ingredients. Slightly different versions could be mounted on aircraft wings to alert pilots when ice begins to form.

A Cool Idea; May 1998; Scientific American Magazine; by Alpert; 1 Page(s)

The refrigerator of the future may be sitting in a laboratory in Madison, Wis. It doesn¿t have an ice-cube maker or a vegetable crisper. Nor does it have the standard gas-compression cooling system. What it does have are two cylinders of powdered gadolinium--a dense, gray, rareearth metal--and a superconducting magnet. The device is the first magnetic refrigerator working at near-room temperature to produce substantial amounts of cooling power--more than 500 watts, three times the power of a large household refrigerator.

Carl B. Zimm, senior scientist at Astronautics Corporation of America, led the development of the magnetic refrigerator under a contract with the U.S. Department of Energy¿s Ames Laboratory. It relies on the magnetocaloric effect, the ability of ferromagnetic materials to heat up in the presence of a magnetic field and cool down when the field is removed. When a ferromagnet, such as gadolinium, is placed in a magnetic field, the magnetic moments of its atoms become aligned, making the material more ordered. But the amount of entropy in the magnet must be conserved, so the atoms vibrate more rapidly, raising the material¿s temperature. Conversely, when the gadolinium is taken out of the field, the material cools.

Cyber View; May 1998; Scientific American Magazine; by Grossman; 1 Page(s)

How many bombs would it take to bring the Net down, and where would you drop them?" This kind of question can silence a roomful of Netheads, and so it did at a panel presented at the Computers, Freedom and Privacy Conference, held this past February in Austin, Tex. The group needs no reminding that, historically, the Net was built to withstand precisely that: nuclear-bomb outages. "Zero" was the consensus of Matt A. Blaze and Steve M. Bellovin, both researchers specializing in network security at AT&T and both Net heroes--Blaze for leading the technical wing of the protests against government regulation of cryptography and Bellovin for being one of the three 1979 creators of Usenet.

"Zero" is not good news, because it turns out there are far more effective ways of crippling the Internet, whether by malice or accident. In the past year several incidents, most accidental, have demonstrated the problem, all of which had to do with the routing of traffic around the Net. Routers depend on having access to accurate information to match numbered addresses to named domains, such as ".com." That information is stored in about a dozen worldwide root servers, which are top-level computers that hold the database that matches names and addresses.

Six Months on Mir; May 1998; Scientific American Magazine; by Lucid; 10 Page(s)

For six months, at least once a day, and many times more often, I floated above the large observation window in the Kvant 2 module of Mir and gazed at the earth below or into the depths of the universe. Invariably, I was struck by the majesty of the unfolding scene. But to be honest, the most amazing thing of all was that here I was, a child of the pre-Sputnik, cold war 1950s, living on a Russian space station. During my early childhood in the Texas Panhandle, I had spent a significant amount of time chasing windblown tumbleweeds across the prairie. Now I was in a vehicle that resembled a cosmic tumbleweed, working and socializing with a Russian air force officer and a Russian engineer. Just 10 years ago such a plot line would have been deemed too implausible for anything but a science-fiction novel.

In the early 1970s both the American and Russian space agencies began exploring the possibility of long-term habitation in space. After the end of the third Skylab mission in 1974, the American program focused on short-duration space shuttle flights. But the Russians continued to expand the time their cosmonauts spent in orbit, first on the Salyut space stations and later on Mir, which means "peace" in Russian. By the early 1990s, with the end of the cold war, it seemed only natural that the U.S. and Russia should cooperate in the next major step of space exploration, the construction of the International Space Station. The Russians formally joined the partnership--which also includes the European, Japanese, Canadian and Brazilian space agencies--in 1993.

How Cicadas Make Their Noise; May 1998; Scientific American Magazine; by Bennet-Clark; 4 Page(s)

In many places the world over, the early dusk of late spring can be quite a noisy time. Every year some of the several thousand species of cicada emerge from underground, and the males begin to sing their raucous, almost deafening, song. Among these virtuosos of the insect realm, the males of one species of Australian cicada (Cyclochila australasiae) are distinguished for having the loudest insect call measured so far.

Transmitting at 100 decibels within a one-meter range at a frequency of 4.3 kilohertz, this cicada has a cry whose volume and intensity resemble that of a personal alarm going off. Except, of course, that the male may not be singing alone but rather with a chorus often of tens or even hundreds of others. So the effect is similar to that of a roomful of simultaneously ringing alarms.

The Genetics of Cognitive Abilities and Disabilities; May 1998; Scientific American Magazine; by Plomin, DeFries; 8 Page(s)

People differ greatly in all aspects of what is casually known as intelligence. The differences are apparent not only in school, from kindergarten to college, but also in the most ordinary circumstances: in the words people use and comprehend, in their differing abilities to read a map or follow directions, or in their capacities for remembering telephone numbers or figuring change. The variations in these specific skills are so common that they are often taken for granted. Yet what makes people so different?

It would be reasonable to think that the environment is the source of differences in cognitive skills--that we are what we learn. It is clear, for example, that human beings are not born with a full vocabulary; they have to learn words. Hence, learning must be the mechanism by which differences in vocabulary arise among individuals. And differences in experience--say, in the extent to which parents model and encourage vocabulary skills or in the quality of language training provided by schools--must be responsible for individual differences in learning.

Television's Bright New Technology; May 1998; Scientific American Magazine; by Sobel; 8 Page(s)

The television set is probably the most successful electronic product of all time. Essentially all homes in developed countries have at least one, and in many countries there are considerably more TV sets than telephones.

This phenomenal success notwithstanding, as an appliance the television set leaves a great deal to be desired. It is boxy, heavy and somewhat delicate. Perhaps most disappointing is that it is not really commercially feasible to make a conventional, picture-tube-based set with a screen size exceeding about 1,000 millimeters (40 inches), measured diagonally. (In this article, millimeters are used for screen measurements, following the convention in engineering.) Besides being extremely expensive, such a set would weigh hundreds of kilograms and would be difficult to get through a standard, 76-centimeter-wide (30-inchwide) residential door. Larger-screen televisions today generally use one of several projection technologies, all of which suffer to some extent from limited brightness or viewing angles in comparison with picture tubes.

Digital Television: Here at Last; May 1998; Scientific American Magazine; by Lim; 6 Page(s)

Within a few months television in North America will undergo a change as fundamental and sweeping as the advent of color. In November broadcasters in large metropolitan areas will begin digital broadcasts, which promise much sharper picture and sound than the current system provides. Called digital television, or DTV for short, the new system also has many features that are absent from conventional broadcasting, such as auxiliary channels for data and easy connection to computers and telecommunications networks.

The changeover from the current system, established in the 1940s and 1950s by the National Television System Committee (NTSC), to the new digital form has been a slow, often contentious process. There were many years of competition and cooperation among major organizations. Officials at the Federal Communications Commission (FCC), broadcasters, television manufacturers and academics tried to come up with a digital standard that would not render existing Tvs immediately obsolete. Some of the details, especially those regarding the introduction of computer services to the television realm, still need to be worked out.

Japanese Temple Geometry; May 1998; Scientific American Magazine; by Rothman; 8 Page(s)

Of the world's countless customs and traditions, perhaps none is as elegant, nor as beautiful, as the tradition of sangaku, Japanese temple geometry. From 1639 to 1854, Japan lived in strict, self-imposed isolation from the West. Access to all forms of occidental culture was suppressed, and the influx of Western scientific ideas was effectively curtailed. During this period of seclusion, a kind of native mathematics flourished.

Devotees of math, evidently samurai, merchants and farmers, would solve a wide variety of geometry problems, inscribe their efforts in delicately colored wooden tablets and hang the works under the roofs of religious buildings. These sangaku, a word that literally means mathematical tablet, may have been acts of homage--a thanks to a guiding spirit--or they may have been brazen challenges to other worshipers: Solve this one if you can!

A Calculus of Risk; May 1998; Scientific American Magazine; by Stix; 6 Page(s)

Months before El Ni¿o-driven storms battered the Pacific Coast of the U.S., the financial world was making its own preparations for aberrant weather. Beginning last year, an investor could buy or sell a contract whose value depended entirely on fluctuations in temperature or accumulations of rain, hail or snow. These weather derivatives might pay out, for example, if the amount of rainfall at the Los Angeles airport ranged between 17 and 27 inches from October through April. They are a means for an insurer to help provide for future claims by policyholders or a farmer to protect against crop losses. Or the contracts might allow a heating oil supplier to cope with a cash shortfall from a warmer than expected winter by purchasing a heating degree-day floor--a contract that would compensate the company if the temperature failed to fall below 65 degrees as often as expected. "We¿re big fans of El Ni¿o because it¿s brought us a lot of business," comments Andrew Freeman, a managing director of Worldwide Weather Trading, a New York City¿based firm that writes contracts on rain, snow and temperature.

Weather derivatives mark an example of the growing reach of a discipline called financial engineering. This bailiwick of high-speed computing and the intricate mathematical modeling of mathematicians, physicists and economists can help mitigate the vagaries of running a global business. It entails the custom packaging of securities to provide price insurance against a drop in either the yen or the thermometer. The uncertainties of a market crash or the next monsoon can be priced, divided into marketable chunks and sold to someone who is willing to bear that risk--in exchange for a fee or a future stream of payments. "The technology will effectively allow you to completely manage the risks of an entire organization," says Robert A. Jarrow, a professor of finance at Cornell University.

The Amateur Scientist; May 1998; Scientific American Magazine; by Carlson; 2 Page(s)

As I write this column, I am enjoying my regular Sunday morning bagel at a small café overlooking the ocean. It's raining, and storms at sea have whipped up unusually large waves. These ribbons of energy march thousands of miles in lockstep, finally breaking on Pacific beaches with spectacular effect. Watching these watery monsters roll up onto the nearby sand reminds me of another kind of wave passing by. The world's greatest ocean is the atmosphere, and it, too, contains extraordinarily powerful waves. Like their ocean-going counterparts, atmospheric waves are normally generated by energetic storms. But they can also arise and spread, like ripples on a quiet pond, when a meteor or volcanic explosion violently shocks the air.

Yet even the largest atmospheric tsunamis are quite difficult to detect. The pressure excursions that betray their passage are typically just a few millibars (thousandths of one atmosphere), and these tiny undulations often take tens of minutes, or even longer, to go by. Instruments that can monitor such subtle signals are called microbarographs, and professional units can cost thousands of dollars. But, thanks to Paul Neher, a gifted amateur scientist from Las Cruces, N.M., anyone can now observe these ephemeral waves for about $50.

Mathematical Recreations; May 1998; Scientific American Magazine; by Stewart; 3 Page(s)

The prestigious journal Nature manages to combine highpowered research papers with eclectic science writing. One of its regular columns is Art and Science, whose name pretty much speaks for itself. In the December 11, 1997, issue, art historian Martin Kemp describes the remarkable landscapes of a London artist named Jonathan Callan. Unlike conventional landscape art, Callan¿s works are sculptures, not paintings. And his landscapes are unlike anything seen on earth or indeed on any known world. They are three-dimensional forms created by pouring cement onto a perforated board.

Kemp, a professor in the University of Oxford¿s art history department, notes a relationship between Callan¿s sculptures and recent work in the field of complexity theory. Certain general principles seem to govern Callan¿s fantastic landscapes--for instance, the highest peaks of cement occur in the regions farthest from the holes. In a letter to the editor in a later issue of Nature (January 29, 1998), Adrian Webster, an astronomer at the Royal Observatory in Edinburgh, points out that the curious geometry of Callan¿s landscapes can be understood using a more classical branch of mathematics, the theory of Voronoi cells. He also explains how Voronoi cells illustrate one of the major recent discoveries of astronomy, the foamlike distribution of matter in the universe. If ever there was an example of the unity of mathematics, art and science, this has to be it.

Reviews; May 1998; Scientific American Magazine; by Ridley, Weinberg; 4 Page(s)

The emotions are a hot topic of the 1990s. They are the most conspicuous difference between the software of our brains and that of computers, creating a puzzle for artificial-intelligence theorists of what a computer would gain if it had emotions as well as a rational calculating ability. The emotional centers of the brain can be almost missing in some brain-damaged patients, creating a puzzle for neuropsychiatrists of what is wrong with these superficially normal people. And social relationships are lubricated, glued together and dissolved by the emotions, creating a puzzle for many of us of how to deploy them efficiently. Hence the stream of popular scientific books, including Antonio R. Damasio¿s Descartes¿ Error, Daniel Goleman¿s Emotional Intelligence and Joseph LeDoux¿s The Emotional Brain, as well as less scientific features in the glossy magazines and opinions in the talk shows. What does Charles Darwin¿s 1872 classic have to offer here?

One answer is that emotions are expressed not verbally but in body (and particularly facial) language. You can tell someone is angry, for example, from--in Darwin¿s words--"the body being held erect," "the brows being heavily contracted" and "the firmly compressed mouth, the distended nostrils, and flashing eyes." This much was known before Darwin, although his description is more complete and accurate than any of his predecessors. Indeed, it has not been replaced since. The editor of this new edition, Paul Ekman, is professor of psychology at the University of California at San Francisco and an expert on emotional expression. Ekman interpolates occasional comments within the text, usually to explain how Darwin¿s ideas have held up after later work. Darwin¿s descriptions, except for some details of facial muscular contractions, get high marks.

Commentary: Wonders - Double Bass Redoubled; May 1998; Scientific American Magazine; by Morrison; 2 Page(s)

The deepest tones of the church organ were sensations less of ear than of chest to one young choirgirl who sat near the tall pipes. A decade ago biologist Katharine B. Payne, no longer that choirgirl but an investigator of international standing, vividly reexperienced her memorable sensation during a casual visit to the elephant house at a zoo. She and her colleagues have established how elephant families in the wild regularly communicate using sounds mainly inaudible to humans. Their purposeful trumpeting can arrange friendly rendezvous with groups five or 10 miles distant across forest or savanna, at frequencies of 35 hertz (or cycles per second) down to 12 hertz.

The familiar term "ultrasonics" is applied to sound pitched too high for our ears to hear, though not too high for dogs or bats, and for the extremely high frequency submillimeter waves much used for medical close-up imaging. "Infrasonics" is the label for the other end of the acoustic spectrum, far-ranging sounds too low in pitch to be audible. Energy loss in sound transport is the result of internal diffusion that wipes away the contrast between compressed crests and rarefied troughs as any pressure wave advances. The longer the wavelength of the sound, the farther it can go.

Commentary: Connections-Cheers; May 1998; Scientific American Magazine; by Burke; 2 Page(s)

Abarman the other night opened my tonic water bottle with a flourish, and the tinkle of metal reminded me of William Painter, the man who devised the Crown Seal Company bottle cap. (And then blew his Hall of Fame chances by advising one of his salesmen, name of Gillette, to invent a similar use-and-throw-away gizmo, the safety razor.)

At effecting closure--including wax, glass balls and a combo of wire and cork--metal-capped effervescence was first made popularly available by Jacob Schweppes at the 1851 Crystal Palace Exhibition in London. At which he sold vast quantities of soft drinks, thus realizing the long-dead dream of Joseph Priestley, who had invented soda water decades earlier. Getting fizz into water (drinking same, it was thought, would cure yellow fever) was one of Priestley¿s more successful industrialchemistry efforts, all of which were inspired by the modern education he had received at one of the great Dissenter academies. These had originally been set up in late 17th-century England by Protestants who wouldn¿t accept the return of a monarchy after the failure of Oliver Cromwell¿s Puritan Commonwealth. These guys opened their own schools because those who had refused to sign an oath of allegiance to the throne were barred from going to university, becoming members of Parliament, preaching or trading in the major cities, and taking jobs in the army. So went their options for advancement.

Working Knowledge; May 1998; Scientific American Magazine; by Dragon; 1 Page(s)

Polymerase chain reaction (PCR) is a technique that mimics nature¿s way of replicating DNA. First described in 1985, PCR has been adopted as an essential research tool because it can take a minute sample of genetic material and duplicate enough of it for study. PCR has been used to identify the remains of Desert Storm casualties, to analyze prehistoric DNA, to diagnose diseases and to help make identifications in police investigations.

DNA is most often found as a double-stranded molecule, twisted as a helix, in which each strand complements the other. PCR starts with the DNA sample, which is put in a reaction tube along with primers (short, synthetic pieces of single- stranded DNA that exactly match and flank the stretch of DNA to be amplified), deoxynucleotide triphosphates (dNTPs, the building blocks of DNA), buffers and a heat-resistant enzyme (polymerase). Heating the mixture separates the "template" strands of DNA. Then, at varying temperatures, the rest of the components in the mixture spontaneously organize themselves, building a new complementary strand for each original.