Scientific American Magazine
Cover; June 1997; Scientific American Magazine; by Staff Editor; 1 Page(s)
Table of Contents; June 1997; Scientific American Magazine; by Staff Editor; 2 Page(s)
From The Editors, including Masthead; June 1997; Scientific American Magazine; by Rennie; 1 Page(s)
Letters To The Editors; June 1997; Scientific American Magazine; by Staff Editor; 1 Page(s)
50, 100 and 150 Years Ago; June 1997; Scientific American Magazine; by Staff Editor; 1 Page(s)
JUNE 1947 COMPETITION FOR LEAD--Plastics are eating their way into former lead applications. They can replace lead in tank linings and pipes in the chemical industry and in cable sheathing in the electrical industry. Substitute pigments are being developed for paints, to take the place of time-honored white lead. Glass and rubber offer many of the inert advantages of lead and are beig used for jobs where lead was formerly the only material considered.
NEW FUNGICIDE--An agricultural fungicide derived from petroleum and sulfur has been developed. The latexlike material holds chemicals so that they cannot be washed away by rain or dew, thus providing maximum killing action against blights and diseases. After spraying and drying, the material forms a microscopic web that can be removed only by scraping, decomposition of the materials, or expansion by growth.
The 1997 National Medal of Technology; June 1997; Scientific American Magazine; by Staff Editors; 4 Page(s)
The next time you are in a movie theater and the sound of a volcano erupting on screen sets your teeth to shaking or the pure sound of music on tape mentally transports you to a concert hall, spare a moment¿s thanks for Ray M. Dolby. Over the past 30 years he has profoundly influenced the science of sound recording and reproduction through his nearly ubiquitous Dolby technologies. Products incorporating his innovations range from the cassettes played in personal headsets and car stereos to the soundtracks of blockbuster films. This year he receives the National Medal of Technology for his inventions and for fostering their adoption worldwide through the products and programs of his company.
Dolby¿s involvement in sound engineering started early. While earning his undergraduate degree in electrical engineering at Stanford University, from which he graduated in 1957, he worked with the team at Ampex Corporation that produced the first practical video recorder. Dolby went on to receive his doctorate in physics from the University of Cambridge in 1963.
In Focus: Pinning Down Inflation; June 1997; Scientific American Magazine; by Horgan; 2 Page(s)
In 1979 a young physicist at the Stanford Linear Accelerator, while tinkering with some leading theories of elementary particles, reached a startling conclusion. Under the extreme conditions that might have prevailed in the primordial universe, gravity may have briefly become a repulsive rather than attractive force, causing the cosmos to undergo a stupendous growth spurt before subsiding to the relatively sedate expansion observed today. His excitement mounting, Alan H. Guth wrote "SPECTACULAR REALIZATION" in his notebook and set it off from the surrounding equations with two concentric boxes.
Guth¿s exhilaration turned out to be warranted. His theory, which he called inflation, explained some of the universe¿s fundamental features, such as the uniformity of the big bang¿s afterglow. The cosmological community immediately embraced inflation, as Guth himself recounts in his new book, The In- flationary Universe. More than 3,000 papers on the topic have been published in peer-reviewed scientific journals since Guth¿s original article in 1981. Many theorists would agree with Alan P. Lightman of the Massachusetts Institute of Technology that inflation is "the most significant new development in cosmological thinking" since the big bang theory itself.
War Without End?; June 1997; Scientific American Magazine; by Beardsley; 2 Page(s)
As an international push gathers force to ban antipersonnel land mines, new technologies show promise for speeding up humanitarian mine clearing. But negotiations in Geneva aimed at a global ban on the weapons are moving slowly, and a senior of- ficial of the Canadian Ministry of Foreign Affairs suggests that the U.S. has not negotiated seriously on an alternative, fast-track Canadian initiative--despite the declaration of 15 retired U.S. military officers that a ban on antipersonnel mines would be "militarily responsible."
At the moment, the U.S. is negotiating a ban through the United Nations Conference on Disarmament in Geneva. But Stephen Goose of Human Rights Watch says it is "increasingly clear to most observers" that the Conference on Disarmament will make little progress. Major mine producers such as China and Russia, as well as some developing countries, have shown scant interest in discussing land mines at the conference, which requires a step-by-step consensus.
BEE Blight; June 1997; Scientific American Magazine; by Mukerjee; 2 Page(s)
For several decades, honeybees in the U.S. have been dying off. The culprits are varied: pesticides, habitat loss and, most acutely, mites. Tiny tracheal mites and the larger varroa mite debilitate and ultimately destroy entire bee colonies. The number of managed colonies fell from roughly six million in the 1940s to three million in 1996. And as for wild honeybees, there are virtually none left, says Hachiro Shimanuki of the U.S. Department of Agriculture¿s Bee Research Lab. The honeybee¿s demise has led some entomologists to seek other kinds of bees to carry the pollen load.
Honeybees (Apis mellifera) are responsible for pollinating up to $10-billion worth of apples, almonds and other crops every year, a far more valuable service than their simultaneous production of $250-million worth of honey. So far there has been no major shortfall in crops, as large-scale producers rent hives from migratory beekeepers--who move their charges north for the summer and south for the winter. (But migration, which enables bees from different hives to mix, probably helped the mite epidemic to spread: in Canada, where bee transport is limited, there is minimal infestation.) The true sufferers will be those with small orchards and backyard vegetable plots, who rely chiefly on pollination by wild honeybees.
In Brief; June 1997; Scientific American Magazine; by Leutwyler; 3 Page(s)
Topping Taxol Last December, Samuel J. Danishefsky and his colleagues at Sloan-Kettering Institute for Cancer Research synthesized epothilone-A, an anticancer chemical produced by bacteria. Now they have artificially made its more potent cousin, epothilone-B. Both epothilones are natural products, as is taxol, the well-known cancer drug first derived from the yew tree. And like taxol, both kill tumor cells by stabilizing microtubules-- organelles that help cells maintain normal shapes.
Screaming Leaves Talking to plants seems reasonable, but listening to them? Physicists at the University of Bonn are doing just that to find out why so many geranium seedlings die in transit from the Mediterranean to Germany every year. To do so, they use a sensitive hearing aid: a laser excites ethylene molecules--gas that plants release when exposed to drought, cold or other forms of stress-- and a resonance tube amplifies the ensuing shock waves. Higher ethylene emissions make for louder sounds. The device should help reveal what disturbs the green refugees.
When Nutrients Turn Noxious; June 1997; Scientific American Magazine; by Beardsley; 2 Page(s)
If global warming seems ominous, consider this new assessment of how humans have disrupted the natural cycling of nitrogen. By using fertilizers, burning fossil fuels and cultivating crops that convert nitrogen into forms plants can use, humankind has over the past century doubled the total amount of atmospheric nitrogen that is converted, or fixed, every year on land. The nitrogen glut is already causing "serious" loss of soil nutrients, acidifi- cation of rivers and lakes, and rising atmospheric concentrations of the greenhouse gas nitrous oxide. Moreover, the oversupply probably explains decreases in the number of species in some habitats, as well as long-term declines in marine fish catches and, in part, the algal blooms that are an unwelcome spectacle in many coastal areas.
Formally published this summer in Ecological Applications, is the work of eight senior ecologists chaired by Peter M. Vitousek of Stanford University. Their study identifies as the chief culprit the industrial fixation of nitrogen gas to make fertilizer. "The immediacy and rapidity of the recent increase of nitrogen fixation is difficult to overstate," the researchers say. More than half the nitrogen fertilizer ever made before 1990 was used during the single decade of the 1980s, they note.
Sex, Flies and Videotape; June 1997; Scientific American Magazine; by Horgan; 2 Page(s)
Science has taken an important step forward in the effort to expose the genetic underpinnings of sexual predilection--in fruit flies. A group led by Michael McKeown of the Salk Institute for Biological Studies in La Jolla, Calif., has found that a single mutant gene, called dissatisfaction, makes female flies too choosy and male flies not choosy enough.
Previous research had shown that females carrying dissatisfaction never lay eggs, but the precise causes of the infertility remained unknown. McKeown and his three colleagues put the mutant females in transparent chambers with normal males and videotaped their shenanigans. Normal females copulate after several minutes of male courtship, which includes poking, licking and vibrating a wing--or "singing," as the investigators describe it in the February 4 issue of Proceedings of the National Academy of Sciences.
By the Numbers: Lung Cancer in U.S. Males; June 1997; Scientific American Magazine; by Doyle; 1 Page(s)
The U.S. is now in the seventh decade of a lung cancer epidemic that started with the introduction of milder, more inhalable cigarettes near the turn of the century. Because of the disease¿s long incubation period, lung cancer mortality did not rise until the 1930s, but as early as 1912, critics were claiming that cigarettes caused cancer. There was, however, no strong evidence until 1950, when published reports showed smoking to be far more common among those with the disease. Later research confirmed beyond a reasonable doubt that smoking not only caused most lung cancer--more than 80 percent--but also contributed to a variety of other diseases. The Centers for Disease Control and Prevention estimates that 420,000 Americans died of a smoking-related disease in 1990 and that, of these, 28 percent died of lung cancer, 24 percent of coronary heart disease, 19 percent of other forms of cardiovascular disease and 15 percent of obstructive lung diseases, such as emphysema. About half of those who start smoking regularly as teenagers can expect to die before their time from a smoking-related disease.
Geographically, lung cancer mortality among men follows roughly the prevalence of cigarette smoking but also reflects local habits and practices, such as those of the Cajun population of Louisiana, who are heavy users of hand-rolled cigarettes. Another factor influencing the pattern on the map is occupational exposure to carcinogens, for example, in the shipyards of the Gulf and South Atlantic coasts. Other factors include availability of high-quality medical care (low in many parts of the South), religion (Mormons, among others, proscribe smoking), air pollution, radiation and possibly even diet. Smoking tends to be higher among blue-collar workers and the less well educated. Between 1987 and 1990 about 40 percent of blue-collar men smoked, compared with 24 percent of white-collar men. A 1993 survey showed that among those with less than a high school education, 37 percent smoked, compared with 14 percent of college graduates and, from a different survey, 6 percent among the most highly educated--doctors, dentists and clergy, for instance.
Anti Gravity: Small Fry; June 1997; Scientific American Magazine; by Mirsky; 1 Page(s)
Douglas Tallamy returned from an insect-collecting trip in April to find a message on his answering machine. Being a professor of entomology at the University of Delaware, Tallamy often goes bug hunting. Being a human being, he often gets phone messages. The messages, however, never before included threats from lawyers.
How the lawyers discovered Tallamy dates back to another trip, taken three years ago. "I had driven through the tollgates after the Delaware Memorial Bridge, and they had bug zappers," he said. "And I remember sitting there and watching the bugs get zapped."
Profile: Raymond V. Damadian; June 1997; Scientific American Magazine; by Schneider; 2 Page(s)
On a chartered bus somewhere outside Washington, D.C., Raymond V. Damadian lifts a megaphone to his mouth and addresses his fellow passengers, as if acting as a tour guide. Instead of describing the historic attractions in the city they are about to visit, he reviews why they have been traveling the interstate since the wee hours of the morning and what they might say when they arrive at the Capitol and meet with their elected representatives. Most of his audience probably need little reminder, but this scientist, inventor and entrepreneur wants there to be no doubt about the seriousness of their mission. To his mind, they are there to avert a national disaster.
The catastrophe he foresees is the demise of effective patent protection for the country¿s inventors. And Damadian is certainly one to speak for that group. Twenty years ago, in a basement laboratory at the Downstate Medical Center in Brooklyn (part of the State University of New York), Damadian designed and built a machine he had conceived--and patented--some six years earlier: a medical scanner that could probe the body using the phenomenon of nuclear magnetic resonance. This first prototype for magnetic resonance imaging, which he dubbed "Indomitable," is now held by the Smithsonian Institution, along with Edison¿s lightbulb and the Wright flyer.
Seller Beware; June 1997; Scientific American Magazine; by Zorpette; 2 Page(s)
Several years ago, in the wake of the war in the Persian Gulf, a "new world order" was proclaimed. Nations would work together to isolate and contain rogue countries that flouted international treaties or standards of decency. It was a good if obvious idea. But it was difficult to reconcile with the fact that numerous Western companies--with the tacit approval of their governments--had supplied the high-tech equipment and materials that enabled various rogue countries, such as Iraq, to embark on programs to produce weapons of mass destruction.
Six years after the war ended in the Gulf, some observers claim that the same pattern of technology acquisition that enabled Iraq to sustain nuclear- and chemical-weapons programs is occurring in Iran. Moreover, German hightech companies--whose products turned up in abundance in the Iraqi nuclearand chemical-weapons programs--are once again at the center of controversy. "The U.S. has been widely concerned over the past five years with what our Western allies, particularly the Germans, have been doing with the Iranians," says David A. Kay, a national security expert in the McLean, Va., office of Science Applications International Corporation.
Floating Giants; June 1997; Scientific American Magazine; by Stix; 1 Page(s)
Offshore oil rigs are feats of modern engineering, able to weather monster waves and hurricane-force winds while producing the lifeblood of modern society. In coming years, the technology that mines black gold from under the sea may be deployed for other uses, from launching rockets to landing airplanes.
Beginning in 1998, a converted offshore oil-drilling platform is slated to become the launching site for rockets that will take satellites into orbit from a location more than 1,000 miles southeast of Hawaii. Sea Launch, consisting of four companies led by Boeing Commercial Space, plans to take advantage of the additional rotational speed at the equator to give rockets more momentum for lifting satellites into a fixed geostationary orbit. Launching from the equator also means that a satellite is already aligned with its orbital path and does not have to be repositioned from another latitude.
Medical Mismatch; June 1997; Scientific American Magazine; by Mukerjee; 2 Page(s)
On the ides of March, 13,554 graduating medical students in the U.S. each opened an envelope. The dreaded missives named the hospitals where they would go for their residencies. "It¿s serious business," says Kevin J. Williams of Jefferson Medical College. If he has his way, the 1997 rite of passage will be the last to have the odds stacked against the students.
Williams himself went through the National Resident Matching Program (NRMP) in 1980. The program, subscribed to by most medical colleges, requires students to first apply to the hospitals. After interviews, the students rank the hospitals in order of preference, while the hospitals similarly rank the students. The NRMP then matches the participants via an algorithm, with the final results being binding. On examining the formula, Williams, Victoria P. Werth (his wife), and classmate Jon A. Wolff discovered that contrary to the NRMP¿s claims, it was biased against the students.
Spying Saucer; June 1997; Scientific American Magazine; by Zorpette; 1 Page(s)
Among the hundreds of experimental machines built to go where humans cannot (or should not), there have been rollers, crawlers, fliers, orbiters and undersea cruisers. Now there is a flying saucer, and it is boldly going where no flying drone has gone before. It is meandering down urban streets, peeping in windows and setting down gently on the roofs of buildings.
Appropriately enough, demonstrations of the saucer¿s capabilities are coinciding with the 50th anniversary of the notorious incident in Roswell, N.M. In that event, which occurred during the evening of July 2, 1947, a downed balloonlike device, part of a secret U.S. Air Force project, caused an enduring sensation when it was mistaken for a flying saucer of extraterrestrial origin. Ironically, the real flying saucer, which is called Cypher, has not yet provoked any similar episodes, partly because timely articles in the local press at some of the places where the saucer has been flown have explained its earthly origins and missions. (This article is not part of an insidious cover-up conspiracy. Honest!)
Attacking Arthritis; June 1997; Scientific American Magazine; by Nemecek; 1 Page(s)
For some people, aches and pains in the joints flare up with bad weather. But for the more than two million Americans suffering from rheumatoid arthritis, stiff and swollen joints are the result of an internal storm in the immune system. Chemicals that the body normally releases to fight off infections flood the tissues in the joints, attacking them as though they were foreign invaders, eventually eroding the cartilage and bone. Over the past several decades, doctors have had few options for treatment. As knowledge of the immune system has expanded, however, researchers have developed various new drugs that aim to knock the body¿s defense system back in line.
Last fall, at a meeting of the American College of Rheumatology (ACR), several groups presented results on three novel therapies, all of which work by interfering with the deluge of chemicals released by the immune system in the course of rheumatoid arthritis. (The illness is distinct from the more common osteoarthritis, which stems from a lifetime of wear and tear on the joints.) Researchers at Amgen described their initial trials of a drug that inhibits the activity of interleukin-1, the naturally occurring protein that induces inflammation by activating the cells lining the blood vessels.
Cyber View; June 1997; Scientific American Magazine; by Eisenberg; 1 Page(s)
We are seeing a growing disenchantment with the Internet, nowhere more strikingly than in media coverage of the cult Heaven¿s Gate and the mass suicide of 39 of its members. Countless accounts blamed the World Wide Web for the tragedy. Cable television¿s CNN led the attack, presenting a view of the Internet teeming with mad Web page workers (several members of the cult designed cut-rate Web sites) and lonely, vulnerable surfers (one recruit may have seen the group¿s Web page before joining). Newspapers, magazines and radio stations followed suit, from the New York Times editorial page to Newsweek-- its cover story ran with the headline "Web of Death" and opened, "They were watching the skies--and the Internet--for a sign."
Actually, the sign most likely came not from the Internet but from the radio. The cult probably learned about the object they believed was a "mothership" waiting to take them away by means of a November radio broadcast. Amateur astronomer Chuck Shramek of Houston, who had recorded an image of Comet Hale-Bopp that showed a "self-luminous Saturn-like object" nearby, talked about the object on Coast to Coast AM with Art Bell, a late-night radio talk show popular with UFO believers. (Shramek bills himself as a "noted expert in 41 fields not currently recognized as science by Harvard, M.I.T. or Yale.") The show evoked a massive callin, and the host repeatedly told worried listeners that the object, which became known as an SLO, was very real.
Iran's Nuclear Puzzle; June 1997; Scientific American Magazine; by Schwarzbach; 4 Page(s)
When the Iranian government announced in 1995 that it had signed contracts totaling $940 million with the Russian Ministry of Atomic Energy to complete a commercial nuclear power plant near the town of Bushehr, the U.S. response came immediately. U.S. Secretary of State Warren Christopher campaigned to convince the Russians that the proposed sale would contribute to the proliferation of nuclear weapons by helping Iran assemble an atomic arsenal.
Although Christopher¿s entreaties were rebuffed, little progress has been made over the past two and a half years on the ambitious project, which many experts believe will ultimately cost far more than $940 million. Nevertheless, Bushehr, on the Persian Gulf, is emblematic of Iran¿s baffling foray into nuclear technology. At the heart of this puzzle is a question: Why would a country with enormous reserves of natural gas and other fossil fuels, and with a gross domestic product of only $62 billion, commit itself to spending perhaps billions of dollars on a nuclear plant that could not possibly generate electricity as cost-effectively as a natural-gas plant? The question is difficult to answer realistically unless the Bushehr plant is viewed as a foothold from which Iran could climb toward an atomic bomb.
Configurable Computing; June 1997; Scientific American Magazine; by Villasenor, Mangione-Smith; 6 Page(s)
Computer designers face a constant struggle to find the right balance between speed and generality. They can build versatile chips that perform many different functions relatively slowly, or they can devise application-specific chips that do only a limited set of tasks but do them much more quickly. Microprocessors (such as the Intel Pentium or Motorola PowerPC chips commonly found in personal computers) are general purpose: programming instructions encoded in binary format can lead a microprocessor through virtually any logical or mathematical operation a programmer can conceive. The Intel Pentium, for example, was never designed specifically to execute either Microsoft Word or the computer game DOOM, but it can run both.
In contrast, custom hardware circuits, often known as application-specific integrated circuits (ASICs), provide precisely the functionality needed for a specific task. By carefully tuning each ASIC to a given job, the computer designer can produce a smaller, cheaper, faster chip that consumes less power than a programmable processor. A custom graphics chip for a PC, for instance, can draw lines or paint pictures on the screen 10 or 100 times as quickly as a general-purpose central processing unit can.
Early Hominid Fossils from Africa; June 1997; Scientific American Magazine; by Leakey, Walker; 6 Page(s)
The year was 1965. Bryan Patterson, a paleoanthropologist from Harvard University, unearthed a fragment of a fossil arm bone at a site called Kanapoi in northern Kenya. He and his colleagues knew it would be hard to make a great deal of anatomic or evolutionary sense out of a small piece of elbow joint. Nevertheless, they did recognize some features reminiscent of a species of early hominid (a hominid is any upright-walking primate) known as Australopithecus, first discovered 40 years earlier in South Africa by Raymond Dart of the University of the Witwatersrand. In most details, however, Patterson and his team considered the fragment of arm bone to be more like those of modern humans than the one other Australopithecus humerus known at the time.
The age of the Kanapoi fossil proved somewhat surprising. Although the techniques for dating the rocks where the fossil was uncovered were still fairly rudimentary, the group working in Kenya was able to show that the bone was probably older than the various Australopithecus specimens previously found. Despite this unusual result, however, the significance of Patterson¿s discovery was not to be confirmed for another 30 years. In the interim, researchers identified the remains of so many important early hominids that the humerus from Kanapoi was rather forgotten.
Panoramas of the Seafloor; June 1997; Scientific American Magazine; by Pratson, Haxby; 6 Page(s)
In 85 B.C. or thereabouts, a Greek named Posidonius set sail on a curious mission. He was not carrying freight or passengers, nor was he engaged in war. He simply wanted to answer an age-old question: How deep is the ocean? Halting his vessel in the middle of the Mediterranean Sea, Posidonius coaxed his ship¿s crew to let out nearly two kilometers of rope before a large stone attached to the end of the line finally hit bottom. He and his men must have been jubilant--at least until they realized that they then had to haul the great weight back on board.
For the next 2,000 years, naval surveyors and oceanographers continued to use exactly the same laborious line-and-sinker method to probe the ocean¿s depths. It is not surprising that they made scant progress. Then, during the 1920s, oceanographers developed the first echo sounders--instruments that could measure the water¿s depth by bouncing sound waves off the bottom. With the wealth of measurements these devices provided, scientists got their first glimmers of the true shape of the ocean basins.
Searching for Digital Pictures; June 1997; Scientific American Magazine; by Forsyth, Malik, Wilensky; 6 Page(s)
The Internet and the digital libraries being connected to it can provide access to enormous amounts of information. Retrieving that information efficiently is another matter. Consider archives of still images or film clips: if a user wants to find something as simple as a picture of a horse near water, the only hope today would be that someone had properly captioned all such pictures in advance.
Experience from major archives shows that it is almost impossible to anticipate all likely queries. Furthermore, support for a new class of query--for example, "Show me all pictures that contain a horse and grass"--might require reexamining the entire collection.
Making Gene Therapy Work: Table of Contents; June 1997; Scientific American Magazine; by Staff Editor; 1 Page(s)
Overcoming the Obstacles to Gene Therapy; June 1997; Scientific American Magazine; by Friedmann; 6 Page(s)
In the late 19th century, when the pioneering architect Daniel H. Burnham was planning some of the first modern skyscrapers, his associates were skeptical about erecting buildings that soared into the clouds. Burnham reportedly warned the skeptics against making "little plans," having "no magic to stir men¿s blood." He urged them to reach beyond traditional architectural boundaries, to think once inconceivable thoughts and to perform previously unimagined deeds--the hallmarks of revolutions.
Revolutionary changes have also occurred in medicine over the past few centuries. Witness the new understandings and practices that issued from the introduction of microscopy, anesthesia, vaccination, antibiotics and transplantation. Medicine is now preparing to undergo another epochal shift: to an era in which genes will be delivered routinely to cure or alleviate an array of inherited and acquired diseases.
Nonviral Strategies for Gene Therapy; June 1997; Scientific American Magazine; by Felgner; 5 Page(s)
As Theodore Friedmann notes in "Overcoming the Obstacles to Gene Therapy" on page 96 of this issue, many efforts at developing gene therapy employ modi- fied viruses to shuttle into human cells genes coding for potentially therapeutic proteins. The aim is to induce cells that are invaded by a virus to transfer the gene to the cell nucleus. The cells should then "express," or manufacture, the needed protein specified by the gene.
Viruses are effective at transferring genes into cells because they have evolved specialized mechanisms that allow them to bind to specific types of cells and to deliver their cargo efficiently into the cellular interior. Yet the therapeutic use of viruses as gene delivery vehicles, or vectors, entails problems. Some viruses can disrupt the DNA of the cells they infect, with potentially harmful results. Furthermore, weakened viruses can conceivably change inside the body and regain their pathogenic activity. An additional serious limitation is that a patient may generate an immune response to the microbe. Such responses can quickly make a gene therapy useless, because they may either destroy the virus itself or possibly kill the infected cells before the therapeutic gene has a chance to help a patient.
Gene Therapy for Cancer; June 1997; Scientific American Magazine; by Blaese; 5 Page(s)
In 1997 an estimated 1.38 million Americans will be newly diagnosed with cancer. Sadly, the main treatments currently available--surgery, radiation therapy and chemotherapy-- cannot cure about half of them. This sobering fact has spurred serious efforts to develop additional strategies for treating the disease--ones based on the biology behind it. To that end, scientists are turning toward gene therapies, which involve introducing into the body genes that can potentially combat tumors.
Researchers initially explored gene therapies for remedying conditions caused by defective genetic instructions, or mutations, passed on from one generation to the next. Most cancers are not inherited in this way but instead result from acquired mutations, produced by external factors such as tobacco smoke or high doses of radiation--or just pure bad luck. These mutations accumulate in cells over time, ultimately rendering the cells unable to control their own growth--an inability that leads to cancer.
Gene Therapy for the Nervous System; June 1997; Scientific American Magazine; by Ho, Sapolsky; 5 Page(s)
The prospect of acquiring any chronic illness is disturbing. But for most people, the threat of neurological impairment evokes a special dread. Afflictions such as Parkinson¿s disease or amyotrophic lateral sclerosis (Lou Gehrig¿s disease) progressively rob control of the body. Damage to the spinal cord can create equal misery in just an instant. And Alzheimer¿s disease attacks the very essence of one¿s personality as it destroys the mind.
Unfortunately, physicians and medical researchers have made only limited progress in the battle against such diseases, in large part because the brain and spine are so vulnerable. Unlike many types of cells, neurons (nerve cells) in the central nervous system of adults are typically unable to divide. That fact of life creates the central tragedy of neurological illness or injury: under normal circumstances, neurons that are lost are gone for good, and injured nerve tissue of the brain and spinal cord cannot be expected to repair itself.
What Cloning Means for Gene Therapy; June 1997; Scientific American Magazine; by Mirsky, Rennie; 2 Page(s)
The recently debuted technology for cloning is usually discussed as a means of creating genetic copies of whole adult individuals. This is far from its only use, however. Cloning could be combined with other biotechnologies, either to achieve more novel goals or to improve on previous methods. Although the technique is still in its infancy, and needs to be studied and developed much further, educated musings about cloning¿s ability to inform gene therapy are already being brought to the table. An area that might particularly benefit is germ-line gene therapy-- genetic modifications that could correct a problem for future generations. "I think cloning is going to be used as a tool that will make gene therapy work," comments Lee Silver, a molecular biologist at Princeton University and an expert on reproductive technologies. "For the first time, germ-line gene therapy becomes realistic."
Germ-line therapy, which is not yet being studied in humans, could ideally prevent deadly or debilitating disorders such as sickle cell anemia or cystic fibrosis. Such diseases are typically transmitted silently from generation to generation by people carrying one copy of a defective gene; the disease becomes manifest when two carriers have a child who inherits two copies.
Bringing Schrödinger's Cat to Life; June 1997; Scientific American Magazine; by Yam; 6 Page(s)
"I am sorry that I ever had anything to do with quantum theory," Erwin Schr¿dinger reportedly complained to a colleague. The Austrian physicist was not lamenting the fate of his now famous cat, which he figuratively placed in a box with a vial of poison in 1935. Rather he was commenting on the strange implications of quantum mechanics, the science behind electrons, atoms, photons and other things submicroscopic. With his feline, Schr¿dinger attempted to illustrate the problem: according to quantum mechanics, particles jump from point to point, occupy several places at once and seem to communicate faster than the speed of light. So why don¿t cats--or baseballs or planets or people, for that matter--do the same things? After all, they are made of atoms. Instead they obey the predictable, classical laws quantified by Isaac Newton. When does the quantum world give way to the physics of everyday life? "That¿s one of the $64,000 questions," chuckles David Pritchard of the Massachusetts Institute of Technology.
Pritchard and other experimentalists have begun to peek at the boundary between quantum and classical realms. By cooling particles with laser beams or by moving them through special cavities, physicists have in the past year created small-scale Schr¿dinger¿s cats. These "cats" were individual electrons and atoms made to reside in two places simultaneously, and electromagnetic fields excited to vibrate in two different ways at once. Not only do they show how readily the weird gives way to the familiar, but in dramatic fashion they illustrate a barrier to quantum computing--a technology, still largely speculative, that some researchers hope could solve problems that are now impossibly difficult.
The Amateur Scientist; June 1997; Scientific American Magazine; by Carlson; 3 Page(s)
The toy microscope set I got one childhood Christmas almost put me off microscopy for good. Squinting through a cheap plastic eyepiece, manipulating the sloppy focus control with one hand and struggling with the other to position the factoryprepared specimen slides resulted in more neck aches and frustration than reward. So years later when a friend offered me his old professional-quality microscope for a mere fraction of its market value, I hesitated. Besides, I could scarcely see through the dirt-encrusted optics, and the gearing for the traveling stage was so gunked up that it scarcely traveled at all. But a little patience, along with cleaning fluid and grease for the gears, quickly restored this binocular beauty to mint condition. Today I'm convinced it was the best $100 I ever spent.
My vintage Spencer has been my constant companion for more than a decade. With it I have poked about inside plant cells, swum abreast of wriggling sperm and gotten delightfully lost inside floating forests of phytoplankton. Unfortunately, no biological specimen can be enjoyed under a microscope for long before natural processes begin to destroy it. Tissues quickly dry out and shrink, and bacteria begin breaking down the delicate structures of life almost immediately after a specimen dies.
Mathematical Recreations; June 1997; Scientific American Magazine; by Stewart; 3 Page(s)
Factorizing a large number is among the most challenging problems in number theory. Last month I described efficient methods for testing a number with 200 or so digits for primeness. But although these methods may prove that a number is not prime, they do not yield the explicit factors. Can we fill that gap?
Recall that a factor of a number is any number that divides it exactly and that a number is prime if it has no factors other than itself and 1. Next, some "geography." Primeland, the world of prime numbers, is scattered increasingly thinly and rather randomly along the number line. But Factorland, the world of integers, is very different. Embedded in it are the primes, which have only one factor--themselves. Most numbers are not prime; obviously one number in two is a multiple of 2, one in three a multiple of 3, and two thirds are multiples of either 2 or 3. (Why not five sixths? Think about it.) But a significant proportion of numbers don¿t have any small factors at all. If you can find just one factor of a number, then the rest are factors of the quotient, which is smaller; so the main difficulty is to find the first one.
Reviews; June 1997; Scientific American Magazine; by Damasio, Beardsley, Powell; 4 Page(s)
We may never understand exactly why emotion was given the cold shoulder of science for almost 100 years. By the last quarter of the 19th century, Charles Darwin, William James and Sigmund Freud had thought and written brilliantly about the nature of emotion, about the possible biological mechanisms behind it and about the ways in which it could be disturbed. The British neurologist John Hughlings Jackson had even made a first stab at discerning the anatomy of human emotion by planting it in the right cerebral hemisphere. There would have been every reason to expect that the budding brain sciences would concern themselves with emotion in much the same way they had been taking on language or visual perception.
Curiously, it never came to pass. Emotion was consistently left out of the mainstream of what became neuroscience and cognitive science. A handful of psychologists, such as Stanley Schachter of Columbia University, carried on important studies on emotion; psychiatrists and pharmacologists concerned with mood disorders developed and applied drugs that gave indirect information on the mechanisms of emotion. By and large, however, neuroscience and cognitive science neglected emotion until quite recently. In what may have been the last gasp of post-Cartesian and post-Kantian intellectual dryness, emotion was not trusted, in real life or in the laboratory. Too subjective, it was said, too elusive, let¿s face it, too irrational for the likes of modern science.
Commentary: Wonders - wrapping up Science and Art; June 1997; Scientific American Magazine; by Morrison, Morrison; 2 Page(s)
Technology, the aggregated tools of complex societies, sustains our everyday lives. Its benefits are utilitarian. We count on it to heal our own ills and indeed to work ill on our wartime enemies. Its flaws require a separate story, a long one.
Yet with similar vigor, high technology has entered the domain of play. Bold ocean-faring yachtsmen now rival the clipper masters of the tea trade. One person may be both captain and crew, using servos to replace dozens of able seamen in the rigging. Hardware and software alike take part; reliable radioed forecasts of favorable winds to come are only less important than the light-composite hulls. The lonely runner, too, benefits from well-designed shoes and track underfoot, possibly even more from the new physiology of pacing and diet (not to mention illicit steroids able to reconstruct an athlete¿s very musculature).
Commentary: Connections - Notice the Difference; June 1997; Scientific American Magazine; by Burke; 2 Page(s)
Iwas jogging along the Azorean pavements in predawn dark on New Year¿s Day and listening to the radio through my headphones when the incongruity struck me. Here I was, in the mid-Atlantic and plugged into the usual semiliterate stuff on the BBC World Service, all because back in the early 1940s somebody made a fuss about B-29s. Those planes¿ delicate onboard vacuum valves were vulnerable to the shakes and to temperature extremes--pretty much standard operating procedure on any bombing mission. No surprise then that the postwar Bell Labs work of John Bardeen, Walter H. Brattain and William B. Shockley got the 1956 Nobel for producing the solid-state, drop-it-onthe- floor-no-problem transistor made out of germanium and so brought enlightenment to the early-morning ear.
Solid-state amplifiers turned out to be just what people working on masers wanted. Researchers could get around coaxing microwaves out of excited ammonia gas molecules and graduate to the big time with doped crystals. Once the molecules of these crystals got excited enough to give off light, voil¿ a laser. The beam spread so little you could shine it at the moon and see where it lit. One reason for the excitement, in more sense than one, was a dopant called neodymium. If you pointed just a little illumination at it, at the right frequency, the molecule would shoot off a ton of laser light. So you got a lot more bang for your buck, as it were.
Working Knowledge; June 1997; Scientific American Magazine; by Katz; 1 Page(s)
Spurred by the belief that excessive coffee drinking had poisoned his father, the German chemist Ludwig Roselius, in about 1900, found a number of compounds that dissolved the natural caffeine in coffee beans without ruining the drink¿s taste. Chloroform and benzene did the job but were toxic, so for 70 years methylene chloride became the solvent of choice.
When it was discovered in the 1980s to be a suspected carcinogen, the chemical was abandoned by all the big U.S. coffee labels. The Food and Drug Administration continues to permit the use of methylene chloride if the residues in the coffee are below 10 parts per million. Processing for specialty decafs still often uses it because it perturbs other flavorings so little.