News this Week

Science  04 Feb 2000:
Vol. 287, Issue 5454, pp. 778
  1. 2001 BUDGET

    How NSF Came Up With the Biggest Boost in Its History

    1. Jeffrey Mervis

    Bill Clinton got the scientific community's attention last month when he said that he aims to give the National Science Foundation (NSF) a record-breaking increase in 2001 (Science, 28 January, p. 558). The numbers, to be released officially on 7 February, sound remarkable—a proposed 17% boost that would be the largest in percentage terms since the Bush presidency and, at $675 million, the biggest dollar increase in the foundation's 50-year history.

    But the numbers don't tell the whole story. The overall request for $4.6 billion would actually provide a bit more money than NSF officials had sought under the most likely of three budget scenarios. At the same time, it shifts funds from what NSF had labeled as priorities into other areas of research. Ironically, the 2001 budget now tackles head-on a problem—the need to sustain “core” disciplines—that NSF officials have argued is important but did not address directly in their request. In the end, to paraphrase Mick Jagger, you might say that even if NSF didn't get what it wanted, at least it got what it needed.

    The budget deliberations for 2001 officially began last fall, when NSF director Rita Colwell and other agency chiefs submitted their requests to the Office of Management and Budget (OMB). Like the three bears, Colwell actually set out several servings for OMB to choose from—a big dish that would immediately double NSF's $3.9 billion budget, a small one that would freeze current spending (as OMB was required to consider), and a midsize or “investment” increase of 15% that NSF hoped the president might actually support. The last included generous helpings of research in nanotechnology, information technology, and biocomplexity, as well as new efforts to improve the scientific workforce. Except for biocomplexity (Science, 10 December 1999, p. 2068), they are all cross-disciplinary initiatives in hot areas that echo Clinton Administration priorities. It's an approach that NSF and other agencies have used successfully in the past to squeeze research money from a cost-conscious OMB.

    But this year, a new concern about the distribution of research funds across all fields came into play. Colwell and others—including Neal Lane, her NSF predecessor, who is now serving as the president's science adviser—had been hammering home the idea that the federal government's $80 billion research portfolio is out of whack. The causes, they noted, were recent double-digit increases for the National Institutes of Health (NIH) combined with cuts in the defense and energy research budgets. That imbalance, they argued, needs to be corrected quickly to assure progress in all areas. At the same time, Colwell has also campaigned for larger, longer grants, noting that NIH awards, on average, are roughly four times the $70,000 median at NSF. The change, she says, would allow researchers to do better science by giving them more time between applications and more resources. It would also reduce paper shuffling and allow NSF to be more efficient.

    Those arguments apparently won over the president and became part of a $2.8 billion science and technology initiative that Clinton unveiled last month in a speech at the California Institute of Technology in Pasadena. For NSF, it translated into a $320 million boost for such fields as chemistry and mathematics, whose growth has lagged behind those areas addressed by the new initiatives. “We have not been effective advocates for our discipline,” says Philippe Tondeur, head of NSF's division of mathematics, where the median grant size is a minuscule $29,000. Mathematicians made a conscious decision many years ago to hold down the size of grants so that more researchers could be funded, he says, but at great cost—halving the normal 2 months' summer salary and stripping out support for most undergraduates, graduate students, and postdoctoral fellows. “It has not been a good strategy,” he admits. “When you look at the pipeline, you see a disaster looming.”

    But while NSF program managers welcome the boost for core disciplines, the increase also revives the perennial debate about how to balance bigger grants with a desire to fund as many people as possible. “The message is, ‘Support the core,’” says Mary Clutter, head of the biology directorate, where the average grant has risen from $80,000 to nearly $100,000 in the past few years. “We're committed to increasing grant size, and hopefully our success rate [about 27%] won't suffer too much.” But she admits that it's not easy to sell the idea to the community: “They figure that some money is better than no money.” She says she's “thrilled” that the choices may not be so stark in this budget.

    A 17% budget increase may allow NSF to do both. But there are still limits. The boost for the core disciplines required small cuts in NSF's request for its special initiatives, although all have emerged with healthy increases. Spending on nanotechnology, to be managed by the engineering directorate, is scheduled to rise from $97 million to $217 million. Information technology, run by the computer sciences directorate, would jump from $517 million to $740 million, and biocomplexity in the environment, now managed by biology, would be boosted from $50 million to $138 million. (These numbers contain some double counting that cannot be sorted out until the budget details are released.) The White House also rejected attempts to divert some of the core money into new facilities not already in the budget. Thus, OMB blocked a last-minute NSF push to shoehorn in a $30 million downpayment for an Integrated Ocean Observing System—a $100-million-a-year network of data-gathering and communications instruments—although NSF won $6 million to continue planning it as part of an interagency initiative in the 2002 budget.

    NSF has won support for other new starts, however, including the first three of a planned 10 or so high-tech ecological field stations, and the first portion of an ambitious network of instruments to monitor seismic activity across the country. Colwell is also touting a proposed major expansion of an effort to create a dozen or more Centers for Teaching and Learning; by last week, NSF had received 115 letters of interest for the pilot phase. The centers aim to train better math and science teachers and improve the skills of those already in the classroom by involving discipline-based faculty in kindergarten through grade 12 education.

    Now that the Administration has spoken, the next steps are up to Congress. NSF supporters take heart from the bipartisan applause by legislators that greeted Clinton's announcement of a science initiative in his State of the Union address last week. But they know that the devil is in the details, and that a lot of political decisions have to fall into place before NSF can get what it needs.

  2. ASTRONOMY

    Signs of MACHOs in a Far-Off Galaxy

    1. Govert Schilling*
    1. Govert Schilling is an astronomy writer in Utrecht, the Netherlands.

    For the past 20 years, astronomers have been using a technique called gravitational lensing to study exotic objects from the universe's infancy, such as superluminous quasars many billions of light-years from Earth. A gravitational lens is a massive object, such as a normal galaxy or galaxy cluster, that happens to lie directly in the line of sight between the object of study and Earth, bending and amplifying its light. But in a recent study carried out by Dutch astronomers, the lens itself turned out to be more interesting than the quasar under examination.

    The radio signal focused by the lens—a normal spiral galaxy like our own Milky Way but 3.5 billion light-years from Earth—appeared to flicker. This odd behavior, the astronomers believe, is caused by compact, dark objects in a halo surrounding the lensing galaxy. The objects themselves appear to be acting as microlenses, focusing the radio signals as they pass through the line of sight. “To explain our observations, you probably need massive objects like neutron stars or black holes,” says Léon Koopmans of the Kapteyn Astronomical Institute in Groningen. If so, it would be the first time that microlensing has spotted such objects—called massive compact halo objects, or MACHOs—in a very distant galaxy.

    Koopmans and Ger de Bruyn of the Netherlands Foundation for Research in Astronomy used the Very Large Array radio telescope in Socorro, New Mexico, and the Westerbork Synthesis Radio Telescope in the Netherlands to study radio waves from a distant quasar known as B1600+434. It is located some 6 billion light-years from Earth in the constellation Hercules. The normal galaxy sitting in front of B1600+434 gives the quasar a “split personality”: Its gravitational pull bends the radio signals passing through it to produce two images of the quasar.

    “The lensing galaxy is a spiral galaxy like our Milky Way, seen exactly edge-on,” says Koopmans. The faintest of the two quasar images is produced by radio signals that pass through the star-studded central bulge and disk of the galaxy, while the brighter image is formed by signals that miss the main galaxy altogether and only pass through its outer dark halo. Surprisingly, the image seen through the galaxy's halo displays extremely fast variations in its brightness. “The radio brightness varies wildly, by as much as 10% in a few weeks,” says Koopmans. The other image remains relatively quiet, however.

    In a paper submitted to Astronomy & Astrophysics, Koopmans and De Bruyn attribute the flickerings to additional lensing by isolated dark objects in the galaxy's halo: The gravity of a compact object passing between the distant radio source and Earth produces short-lived brightness variations. The second image shows no sign of such flickering, they argue, because there are so many microlensing stars in the galaxy's bulge that the sharp peaks are smoothed out.

    If they are right, these observations strengthen the idea that MACHOs account for some of the universe's unseen “missing mass.” Our own Milky Way galaxy is endowed with a similar dark halo, which, according to gravitational studies, must contain a lot of dark matter, but no one is quite sure what form it takes. Microlensing studies at optical wavelengths have turned up tantalizing evidence for MACHOs in the Milky Way's halo (Science, 7 January, pp. 67 and 74); now Koopmans and De Bruyn may have spotted them in a similar spiral galaxy.

    “This sounds very interesting,” says gravitational lens pioneer Anthony Tyson of Bell Laboratories, operated by Lucent Technologies in Murray Hill, New Jersey. “It could certainly give information on the compact forms of dark matter in galaxy halos.” However, he says, some theorists have proposed that a major part of the dark matter in the universe might consist of a diffuse gas of exotic elementary particles, which the microlensing technique would not be able to detect. Since they submitted their paper, Koopmans and De Bruyn have observed even stronger flickerings in B1600+434, up to 30% in less than a month. These results will be presented later this month at a microlens conference in Cape Town, South Africa. “Originally, we derived a lower limit for the mass of the microlensing objects of about half a solar mass,” says Koopmans, “but this may be too conservative. To explain variations of 30%, you probably need objects that are much more massive, like stellar black holes.”

  3. FRANCE

    Street Protests Keep the Pressure on Allègre

    1. Michael Balter

    PARIS“Allègre, resign! Allègre, resign!” Singing and chanting, a contingent of scientists and technicians took to the streets here last week to protest French research minister Claude Allègre's latest attempts to reform the nation's scientific establishment. The 25 January demonstration, estimated by Science at roughly 1000 participants, was organized by five researchers' unions that oppose a number of recent actions by Allègre, including his new push to shake up the CNRS basic research agency and his decision to abandon the SOLEIL synchrotron project in favor of a joint Anglo-French effort to build a synchrotron facility in the United Kingdom (Science, 6 August 1999, p. 819).

    The march began at the University of Paris's Jussieu campus and snaked its way through some of the City of Light's most charming neighborhoods, ending in front of a line of police protecting the research and education ministry on the rue de Grenelle. A delegation of eight union leaders was allowed into the ministry to meet with members of Allègre's Cabinet, although both union and ministry sources told Science that the meeting did not result in either side changing its position. Nevertheless, the demonstration was one of the biggest anti-Allègre actions in recent years. “This march was a big success,” says chemist Jacques Fossey, general secretary of the National Union of Scientific Researchers.

    Fossey and others oppose much of Allègre's new reform plan, which is intended to boost opportunities for young researchers and to make it easier for scientists to move between public research agencies such as the CNRS, the universities, and industry. This is not the first time Allègre has angered French scientists by challenging the status quo. His first major attempt to overhaul French science met stiff resistance a year ago, forcing Allègre to retreat and seek a second opinion. He asked Prime Minister Lionel Jospin to appoint two parliamentary deputies to make their own reform proposals, which ended up echoing many of Allègre's ideas (Science, 30 July 1999, p. 647). Emboldened, Allègre last November directed CNRS president Edouard Brézin and the agency's director-general, Catherine Bréchignac, to come up with some new proposals. But Allègre has now dropped some of his most controversial ideas, such as a significant restructuring of the agency, which many researchers feared would have given more power to the ministry and weakened the CNRS's autonomy in recruiting and evaluating scientists.

    Although Paris's Le Monde newspaper has dubbed the new proposals “reform light,” many key elements of Allègre's original program remain. For example, in a 5 November 1999 letter to Bréchignac, Allègre expressed his desire that researchers' willingness to transfer from CNRS labs to the universities or industry should “become an essential criterion in promotions” to higher paid positions. Bréchignac, who was unavailable for comment, is expected to come up with recommendations for enacting this and other reform proposals by March.

    Now that Allègre has dumped some of the harsher prescriptions for change, many complaints about the reform measures tend to focus on the minister's alleged authoritarian style. Like many other Allègre critics, Fossey accuses the minister of using autocratic methods in pursuit of reform and not sufficiently consulting with the scientific community. As for the SOLEIL decision, Fossey says, “this is the biggest piece of stupidity Allègre has ever carried out.” But key officials involved in the reform effort counter these complaints. Brézin told Science that despite researchers' “concerns about the intentions of [Allègre] toward the CNRS,” the proposals “should not be a source of fear.” And geophysicist Vincent Courtillot, the ministry's director of research, disputes accusations that Allègre's reform efforts have been heavy handed, citing meetings Courtillot has held with researchers in various cities to explain and get feedback on the unfolding reform plans.

    Courtillot also dismisses the importance of last week's demonstration. The protest, he says, “did not represent a significant proportion of the researcher population.” Fossey concedes that the researchers' unions represent a minority of French scientists. For example, only about 12% of researchers at the CNRS and INSERM, France's biomedical research agency, are union members. But he insists that the unions' influence “is much greater than the numbers,” adding, “the battle continues.”

  4. JAPAN

    Blue Laser Pioneer Seeks Greener Pastures

    1. Dennis Normile

    Shuji Nakamura is something of a national hero in Japan. The 45-year-old materials scientist's pioneering work on blue light-emitting diodes (LEDs) has been held up as an example of how Japanese researchers can outperform their colleagues in the United States and Europe, and it has paid off handsomely for his employer, a small Japanese chemical company. But when Nakamura decided to leave industry for academia, he says his destination was a no-brainer: the United States. “Even if you produce some superb invention, your salary and position don't improve [in Japan],” he says.

    Nakamura's arrival this month at the University of California, Santa Barbara (UCSB), will strengthen its already strong program in compound semiconductor materials. He also hopes it will send a message to his native country to rethink its veneration for seniority and credentials over objective measures of performance. Combined with a stifling bureaucracy, the rigid academic hierarchy prevents scientific stars from shining as brightly as they might elsewhere. “It's a very silly salary system,” fixed by law and based strictly on seniority, says Leo Esaki, a physics Nobelist and former president of the University of Tsukuba. Other regulations make hiring technicians and assistants nearly impossible, and collaborations with the private sector are also restricted. In contrast, says Nakamura, “American university professors have a lot of freedom.”

    Nakamura stunned the optoelectronics world several years ago when he beat out dozens of well-funded academic labs and such industrial heavyweights as Sony and Hewlett-Packard to the development of blue LEDs and, later, blue semiconductor lasers (Science, 21 March 1997, p. 1734). The shorter wavelengths allow for a fourfold increase in the storage capacity of CD players and CD-ROM drives over current equipment, which uses infrared lasers to read the digital signals. In addition, blue LEDs join previously developed red and green LEDs to complete the palette of primary colors, enabling long-lasting, energy-efficient LEDs to dominate such niche applications as sports stadium displays. And white LEDs, which combine red, blue, and green LED structures in one device, could eventually make conventional light bulbs obsolete.

    Nakamura's success was based on new fabrication methods for gallium nitride, a material most researchers felt was too difficult to handle. His employer, Nichia Chemical Industries, announced its creation of the blue LED in 1993 and started shipping samples of its blue semiconductor lasers early last year. Thanks largely to Nakamura's research, Nichia's sales have more than doubled in 4 years, to $390 million in 1998.

    With the blue laser now headed for production, Nakamura says he was looking for new challenges. And although he won't criticize his former employer, he admits that he wasn't entirely happy with his position or his compensation. The move dispelled those clouds. His Santa Barbara salary will be “above-scale,” he says, and he has received a $3 million package to set up his laboratory. “Researchers like Nakamura have an international market value,” says Esaki, who 40 years ago left another tiny Japanese company—which later became Sony Corp.—for the greater research support and better pay of IBM's T. J. Watson Research Center in Yorktown Heights, New York, before returning to Japan in 1992. “And Japan has to recognize this if it wants to attract and keep such people.” A Nichia spokesperson declined to comment on Nakamura's pending departure, and Matthew Tirrell, dean of UCSB's College of Engineering and a professor in the materials science department, says simply that “we are delighted to have Shuji Nakamura join us.”

    Even as Nakamura levels his broadside, Japan may be missing an opportunity to improve the academic environment for talented researchers. It is planning to turn the national universities into semi-independent entities, but a spokesperson for the Ministry of Education, Science, Sports, and Culture (Monbusho) says the ministry is leaning toward preserving the status of faculty as national civil servants, subject to all current laws and restrictions. “Most faculty want to continue as national employees because of the employment security,” says the spokesperson, although he notes that a final decision has not yet been made.

    Nakamura believes that such a decision will encourage even more potential or current academics to head overseas. And that exodus, he says, “should say to the Japanese government that current conditions are not very attractive.”

  5. BIOTECHNOLOGY

    Both Sides Claim Victory in Trade Pact

    1. Laura Helmuth

    After 5 years of bitter negotiations, delegates from 130 countries finally hammered out a global treaty that will govern the trade of genetically modified organisms (GMOs). The treaty formalizes the process by which countries can refuse to accept biotech products, an apparent blow to the biotech industry. Even so, both proponents and critics of biotechnology came away from the negotiating table at 5:00 a.m. in Montreal on 29 January claiming victory.

    One reason for the unexpected compromise may be that the wording of the new treaty is decidedly ambiguous. For instance, the treaty allows countries to refuse to import GMOs based on a “precautionary principle”—that is, even without “sufficient scientific evidence” that the products could cause environmental harm or threaten human health. Elsewhere, however, the treaty stipulates that such rejections be based on “credible” scientific evidence.

    The treaty focuses on living modified organisms such as seeds and fish that can colonize an ecosystem. It calls for the creation of a clearinghouse for information about such GMOs. Exporters will be required to register new products with the database, which will be run by the United Nations, and provide scientific information about how they were created and tested. Exporters must also seek permission from importing countries to ship the new products the first time.

    At issue is the safety of GMOs, a topic that has pitted the United States, Canada, and a few other agriculture-exporting countries against the GMO-wary European Union (E.U.) and most developing countries. Asserting that GMOs are safe and a valuable tool for agriculture, the U.S.-dominated team, known as the Miami group, agitated for relatively unrestricted trade in GMOs.

    “The Miami group got virtually everything it wanted,” asserts Val Giddings of the Biotechnology Industry Organization in Washington, D.C. Giddings points out, for example, that the treaty excludes pharmaceuticals, in which the United States has a major stake, and it will not supercede trade agreements under the World Trade Organization (WTO), which encourages relatively unhindered trade of GMOs.

    Biotech opponents read the results differently. “The U.S. lost on most major issues,” counters Philip L. Bereano of The Council for Responsible Genetics in Cambridge, Massachusetts. The Miami group drafted wording that would have allowed the WTO to overrule the biosafety treaty, he says; putting the two agreements on equal footing is seen as a victory by GMO opponents. And Bereano says it is a vindication that the environmentalists' darling, the precautionary principle, is written into the agreement.

    The treaty puts off for 2 years the issue that kept the U.S. and E.U. at each other's throats until early morning in Montreal: whether to include the trade of GMOs that are not likely to propagate in the environment. The treaty states that such “commodity” GMOs intended for food or feed must be labeled “may contain” GMOs. But it does not require exporters to segregate GMO-containing products from traditional products. Some countries and companies already refuse GMO products and pay a premium for nonmodified crops—a market process that is likely to continue until the parties meet again in 2002.

  6. MATERIALS SCIENCE

    Stretching Horizons for Electrical Devices

    1. Adrian Cho

    Hunting for materials that change shape when zapped electrically, researchers have found a new champion literally hanging out in the kitchen. A rubbery acrylic used to stick widgets to refrigerators triples its length when squeezed with high voltage. Known as a dielectric elastomer, the stuff has shattered the standard for electrically induced elongation, researchers report on page 836. The acrylic and its stretchy silicone brethren might someday control video displays, animate small robots, or power artificial limbs.

    Ron Pelrine and his colleagues at SRI International in Menlo Park, California, achieved the record-breaking stretches while searching for better materials for electrical actuators, devices that turn electrical energy into mechanical work. Magnet-and-coil actuators drive stereo speakers, car door locks, and many other familiar electric contraptions. But smaller, higher tech actuators, such as those that guide the tip of a scanning tunneling microscope, rely on materials that deform when stimulated electrically. Substances that perform this trick include piezoelectric crystals, electrostrictive polymers, magnetostrictive alloys, and carbon nanotubes. The measure of motion for such materials is linear strain, the change in length divided by the initial length. The previous best was 41%; the SRI group hiked the figure up to 215%. “I was very excited by these results,” says Ray Baughman, a materials scientist with Honeywell International in Morristown, New Jersey. “The strains you get here are just giant.”

    Pelrine's team fashioned parallel-plate capacitors from films of the elastomers by mounting each film on a rigid frame and painting electrodes of conductive grease on either side. They charged each capacitor to several kilovolts and flattened the material in the middle with an electrical double-whammy known as Maxwell stress. Opposite charges on the two sides of the film attracted each other and squished it like a hamburger between a spatula and a frying pan. Meanwhile, like charges along each surface of the film repelled each other, forcing it to stretch even more. With this technique alone, the researchers set the old record with a silicone elastomer.

    To get even bigger strains, Pelrine and colleagues employed a new twist: stretching the film before they applied the voltage. The prestraining toughened the film so the researchers could apply higher voltages. It also stiffened the film in one direction so that energy from the electrical squeeze was funneled into straining the material in a perpendicular direction. The extra boost enabled Pelrine and colleagues to obtain strains of 117% for a silicone elastomer and 215% for the acrylic.

    Some researchers aren't bowled over by the numbers. “How does this advance the science of the field?” asks Qiming Zhang, a materials scientist at Pennsylvania State University, University Park. The physics behind Maxwell stress is well understood, Zhang says; the interesting question is what underlying mechanism distinguishes the newfound elastomers from other stretchy substances.

    Pelrine says the SRI team focused on finding promising materials. “Basically, we've tried everything we can try,” he says. Indeed, he came across the star acrylic while sticking a plastic safety latch to his refrigerator door and decided to test it. Identifying materials with exotic properties is scientifically worthwhile, Pelrine says, especially if it leads to deeper study. He points to the discovery of high-temperature superconductors, in which huge improvements on the performance of conventional superconductors led researchers to new physical principles. “The jump in performance using the acrylic elastomer, for example, is so large,” he says, “it begs the question of why it is so much better than other elastomers.”

    As for applications, dielectric elastomers provide 100 times more motion but roughly 1/30th as much pressure as piezoelectric crystals. They may therefore prove useful for tasks that require long movements but less pushing or pulling, such as covering and uncovering pixels on video displays or moving the limbs of small robots. Because the materials stretch farther and generate more pressure than living muscle, they may be useful for powering prosthetic limbs. Elastomers currently require high voltages, however, which may limit how they can be employed. “No one actuator technology is going to solve all the problems,” Baughman says.

  7. CANCER RESEARCH

    A Face-Off Over Tumor Blood Supply

    1. Marcia Barinaga

    Last September, cancer biologist Mary Hendrix of the University of Iowa, Iowa City, and her colleagues published a paper in The American Journal of Pathology that stirred up a hornet's nest in cancer research. It suggested that in very aggressive melanomas of the eye, blood-conducting channels that nourish the growing tumor are formed not by the endothelial cells of true blood vessels but by the cancer cells themselves (Science, 3 September 1999, p. 1475).

    If correct, the finding could have major implications for efforts to find new cancer drugs. Currently, drug developers are working furiously to find compounds that inhibit the growth of the new blood vessels around cancer cells. Those drugs are aimed at endothelial cells, however, so they may not work against tumors that use an alternative means to get blood.

    But the work touched off a critical backlash. Some blood vessel specialists and others maintain that the structures the Iowa team described could not be blood-conducting channels. Some of their concerns are presented in a commentary published in the February issue of The American Journal of Pathology. That's unlikely to resolve the issue, however, as Hendrix and her colleagues are sticking to their guns. So time has also been set aside for both sides to thrash out their arguments at a Keystone meeting on angiogenesis in Salt Lake City in early March.

    Pathologist Robert Folberg, a member of the Iowa team and now chair of pathology at the University of Illinois, Chicago, came to the conclusion that very aggressive eye melanomas have unusual blood channels after discovering distinctive looping patterns in slices of the tumors stained with a method called PAS that highlights extracellular matrix. Folberg also noted red blood cells apparently moving through channels formed by the matrix. When he then compared angiograms—pictures of the tumor blood vessels taken after a fluorescent dye had been injected into the patients' bloodstreams—with the PAS staining patterns of slices taken after those same tumors were removed, he saw similar looping patterns in both for the most aggressive tumors. That suggested, Folberg says, that the PAS-stained structures were conducting blood and represented a previously unknown type of blood channel that showed no signs of endothelial cells.

    Blood vessel researcher Donald McDonald of the University of California, San Francisco, who co-authored the American Journal of Pathology commentary with Lance Munn and Rakesh Jain, both of Harvard, says he doesn't question the conclusion that tumors showing the looping patterns are particularly aggressive and deadly. That is “well documented,” he says, but “I just don't buy” the team's assertion that the looping structures are blood-carrying channels.

    McDonald, Munn, and Jain point out that the blood vessels of a tumor are a snarl of tubes, like a plate of hollow spaghetti. An angiogram of that plate would indeed show the noodles looping around in three dimensions. But if you were to slice the spaghetti crosswise as you would a tissue, says Jain, “you would see mostly cross sections of spaghetti,” little circles or ellipses—not the looping strands. So, he and his colleagues conclude, the loopy structures that show up in the PAS-stained cross sections can't be the blood vessels seen in the angiogram. The red blood cells Folberg saw in the putative channels most likely leaked from ordinary tumor vessels, say the authors of the commentary.

    Folberg counters that McDonald and Jain are mistakenly “assuming these things are conventional blood vessels,” which, he says, they are not. The PAS-stained structures are sheets of extracellular matrix wrapped around masses of tumor cells, he says. To illustrate how they could form blood-conducting channels, Hendrix team member Andrew Maniotis resorted to a low-tech demonstration: He used spheres and cylinders of clay to represent masses of tumor cells and surrounded them with aluminum foil to represent the extracellular matrix.

    When he pressed the clay blobs together tightly, as the cell masses would be within a tumor, in most spots, the aluminum foil covering adjacent blobs was in such close contact that no liquid could flow between them. But in some places, because of the curvature of the clay, there were openings that formed ribbonlike channels where liquid could flow. These, the team proposes, represent the blood channels that show up in the angiogram—loopy in shape because they follow the contours of the blobs. In addition, when Maniotis sliced through the clay mass and looked at the pattern made by the aluminum foil, he saw a pattern of back-to-back loops, similar to the PAS-stained pattern. The team recently took another form of the model, made from sausage skins bathed in contrast dye and stuffed with wax, and did a computerized tomography (CT) scan to trace the three-dimensional pattern of the dye in the channels. The CT scan images “look very similar to the angiograms,” says Hendrix.

    Even if the skeptics accept that the clay and sausage-casing models show that such channels can exist in tumors, they say that Hendrix's group will need to do more to show that blood actually flows in the channels. And even if the channels do conduct blood, some question whether the blood flow would have much impact on tumor growth. Blood vessel researcher Adrian Harris of the University of Oxford in the United Kingdom notes that his team, as well as many others, has found that the same type of melanoma studied by the Hendrix group is full of conventional blood vessels. In that case, says tumor biologist Robert Kerbel of the University of Toronto, Ontario, any blood flowing in those channels “could be a very minor percentage of the total [tumor blood flow].”

    Nelson Fausto, editor of the pathology journal, says he deliberately did not show the McDonald commentary to the Hendrix group for their comment because he wanted to let McDonald, Munn, and Jain have their say. But Hendrix will have an opportunity to present her team's models for scrutiny in a debate with McDonald scheduled for the Keystone angiogenesis meeting. Ultimately, however, the Hendrix team's hypothesis is more likely to stand or fall on the results of experiments in animals to nail down the contribution, if any, of the mysterious channels to tumor blood flow.

  8. U.S. PRIZES

    17 Get Science, Technology Medals

    1. David Malakoff

    Researchers who plumbed the depths of the Antarctic ozone hole, helped show that modern cells are assembled from once-independent life-forms, and created reading machines for the blind were among those awarded National Medals of Science and Technology this week by President Bill Clinton. They will be honored at a 14 March ceremony.

    A dozen investigators won the coveted National Medal of Science, which Congress created in 1959, while four investigators and one company gained the prestigious National Medal of Technology, created in 1980. Cellular biologist Lynn Margulis of the University of Massachusetts, Amherst, one of two women honored, helped win acceptance for the once-controversial idea that plant and animal cells are the product of partnerships between ancient, bacterialike organisms. Atmospheric researcher Susan Solomon of the National Oceanic and Atmospheric Administration, an unusually young medalist at 44, was honored for her studies of the South Polar ozone hole. Raymond Kurzweil, founder of Kurzweil Technologies, was recognized for his pioneering work on voice recognition, which has produced many modern aids for the visually impaired.

    The other science winners, by field, are: Biology—David Baltimore, California Institute of Technology; and Jared Diamond, University of California, Los Angeles. Chemistry—Stuart A. Rice, The University of Chicago (UC); and John Ross, Stanford University. Economics—Robert M. Solow, Massachusetts Institute of Technology (MIT). Engineering—Kenneth N. Stevens, MIT. Mathematics—Felix E. Browder, Rutgers University; and Ronald R. Coifman, Yale University. Physical Sciences—James W. Cronin and Leo P. Kadanoff, UC.

    Other National Medal of Technology winners are: computing innovator Glen Culler, Culler Scientific Systems; biotech industry pioneer Robert Swanson (deceased); ARPAnet founding father Robert Taylor (retired); and Symbol Technologies Inc., for development of laser bar code scanning and wireless local area network technologies.

  9. ARCHAEOLOGY

    Earthmovers of the Amazon

    1. Charles C. Mann

    Are the mounds, causeways, and canals in Bolivia's Beni region natural formations or the result of 2000 years' labor by lost societies?

    TRINIDAD, BOLIVIAIn some ways, William Denevan says today, he didn't know what he was getting into when he decided to write his Ph.D. thesis about the Beni, a remote, nearly uninhabited, and almost roadless department in the Bolivian Amazon. Located between the Andes Mountains and the river Guaporé (a major Amazon tributary), the Beni spends half the year parched in near-desert conditions and the other half flooded by rain and snowmelt. But it wasn't until he made his first research trip there, in 1961, that Denevan realized the area was filled with earthworks that oil company geologists—the only scientists in the are—believed to be ruins of an unknown civilization.

    Convincing a bush pilot to give him a flying tour, Denevan examined the earthworks from above. Much of the Beni is covered by a savanna known as the Llanos de Mojos (the Mojos Plains). But, to his amazement, Denevan saw what seemed to be the remains of transportation canals, pyramidlike mounds, elevated causeways, raised agricultural fields, and clusters of odd, zigzagging ridges scattered through the savanna. “I'm looking out of one of these DC-3 windows, and I'm going berserk in this little airplane,” recalls Denevan, who is now a professor emeritus of geography at the University of Wisconsin, Madison. “I knew these things were not natural. You just don't have that kind of straight line in nature.”

    Today, almost 4 decades later, a small but growing number of researchers believe that the Beni once housed what Clark L. Erickson of the University of Pennsylvania, Philadelphia, calls “some of the densest populations and the most elaborate cultures in the Amazon”—cultures fully as sophisticated as the better known, though radically different, cultures of the Aztecs, Incas, and Mayas. Although these still unnamed peoples abandoned their earthworks between 1400 and 1700 C.E., Erickson says, they permanently transformed regional ecosystems, creating “a richly patterned and humanized landscape” that is “one of the most remarkable human achievements on the continent.” To this day, according to William Balée, an anthropologist at Tulane University in New Orleans, the lush tropical forests interspersed with the savanna are in considerable measure anthropogenic, or created by human beings—a notion with dramatic implications for conservation.

    These views have thrust the Beni into what Denevan calls “the Amazon archaeology wars.” For more than 30 years, archaeologists have clashed, sometimes in bitingly personal terms, over whether the vast river basin could provide the resources for indigenous cultures to grow beyond small, autonomous villages. Until relatively recently, the naysayers had the upper hand. In the last decade, though, several archaeologists, including Anna C. Roosevelt of Chicago's Field Museum, have published evidence that such societies did exist throughout the várzea, as the Amazonian floodplain is known, and the bluffs above it (Science, 19 April 1996, pp. 346 and 373; 13 December 1996, p. 1821).

    The dispute over the Beni is similar. Using environmental arguments, skeptics contend that the Beni earthworks must be either natural formations or the remains of a short-lived colony from a richer part of South America—the Andes, most likely. “I haven't seen any basis for thinking there were large, permanent settlements there,” says archaeologist Betty J. Meggers of the Smithsonian Institution in Washington, D.C. “But if they were there, where is the solid evidence?” In particular, critics like Meggers point out, there is no indication of hierarchical organization in the Beni. Without it, they say, the kind of sophisticated society envisioned by Denevan, Erickson, and Balée could not have existed.

    Resolving the controversy may have important consequences for the region—and all of Amazonia. If the region is inherently too fragile to support intensive use, its most appropriate future may be as a biosphere reserve supervised by the United Nations Educational, Scientific, and Cultural Organization (UNESCO)—that is, as an almost uninhabited eco-park. But if human activity has played an essential role in the region's ecological processes for millennia, as Balée argues, then careful human exploitation of the land—such as allowing indigenous people to till land in areas used by ancients—is not only acceptable but essential to preserving its character.

    “Without a doubt the Llanos de Mojos represents one of the most extraordinary prehistoric landscapes anywhere on the face of the planet,” says Robert Langstroth, a cultural geographer who did his 1996 Ph.D. dissertation at the University of Wisconsin under Denevan. “The question is, how much of it is archaeological, and how much did the archaeological parts affect the natural?”

    Anthropological El Dorado

    For centuries, the Llanos de Mojos guarded its story well. A shelf of alluvial deposits as much as 3000 meters deep, the savanna was once rumored to house the golden city of El Dorado. Protected by its clouds of insects, its climactic extremes, and its inhabitants' reputation for fierceness, it was among the last areas in South America reached by Europeans. In 1617, a ragtag band of explorers finally established that El Dorado did not, in fact, exist in the Llanos de Mojos. The Jesuits ruled the area from 1668 to 1767, while disease ravaged the indigenous people.

    Even after the destruction wrought by the Spaniards, the Beni hosted a remarkable mosaic of indigenous societies until the mid-20th century. Its cultural diversity—and the relative lack of knowledge of the area—led the Smithsonian anthropologist Alfred Métraux to call eastern Bolivia “the El Dorado of anthropologists” in 1942. “Some of the Indians came in touch with the Spaniards during the first years of the conquest; [but] others even maintain their independence today and are among the few natives of South America who still live as they did before the arrival of the whites.”

    Despite Métraux's enthusiasm—and the impetus provided by Denevan's later work on the earthworks—the Beni remained largely unexamined. U.S. researchers were put off by Bolivian political instability, by the difficult climate of the area, and by anti-American sentiments fueled by the heavy-handed presence of the U.S. Drug Enforcement Agency in the region. For their part, Bolivian archaeologists focused on the highland civilizations of the Andes, with their enormous, glamorous stone ruins. Only in the 1990s did a Bolivian-American team led by Erickson begin the first long-term archaeological research on the earthworks of the area.

    Cultural mosaic

    Climbing to the top of Ibibate, a forested loma (mound) 18 meters higher than the surrounding savanna, Erickson comes to a bare patch of earth created by a fallen tree. Bending over the uncovered ground, he points out the dark, almost black soil, which is filled with fragments of pottery. Several pieces of pot rim are visible, along with the leg of a vessel shaped like a human foot. Both the richness of the soil and the abundance of the potsherds are typical, in Erickson's view. “Many of the lomas are almost nothing but enormous heaps of sherds,” he says. “I've never seen anything like it—10, 20, 30 feet of sherds.”

    Ibibate—“big mound” in the language of the local Sirionó Indians—is about 50 kilometers east of Trinidad, the provincial capital. The focus of ongoing study by Balée, Erickson, and a team of Bolivian scientists working with Erickson, Ibibate is actually a pair of mounds connected by a short earthen wall. At the edge of the lower, southern mound is a Sirionó hunting camp; the higher mound is used for gathering fruit and nuts. Several earthen causeways radiate out like highways from the mound toward other mounds. Bordered by narrow canals, the causeways are about a meter tall, 3 to 5 meters wide, and straight as a rifle shot. Such features are rare in floodplains, according to Denevan, which to him suggested an artificial origin. Indeed, in Balée's opinion, Ibibate is “as close to a Mayan pyramid as you'll see in South America. … Beneath the forest cover is a 60-foot [18-meter], humanmade artifact.”

    Although their research is incomplete and mostly still unpublished, Erickson and Balée have sketched out a rough outline of what they believe happened here. Ibibate, like most of the hundreds of lomas in the Llanos de Mojos, was initially a much smaller mound, if it existed at all. It was built up, Erickson says, by the original inhabitants of the Beni, although how and why remain uncertain. They could have begun by raising parcels of land to grow crops above the floodwater. Or, according to the late petroleum geologist and amateur archaeologist Kenneth Lee, they may have created the mounds when, for religious reasons, they buried their ancestors in ceramic urns and set up housekeeping on top of them. In either case, the people raised the lomas further by accumulating garbage, the walls and roofs of collapsed wattle-and-daub houses, and, especially, smashed pottery. “The quantity and mass of material deposited indicates that a lot of people were responsible, creating the mounds over a period of at least 2000 years,” Erickson says, “hazarding a guess” that Ibibate typically housed 500 to 1000 inhabitants.

    The villages, each on its own island of higher ground, were anything but isolated. By studying the geographic distribution and variety of the earthworks and their associated pottery, Erickson's team has tentatively concluded that the Llanos de Mojos was the home of not just one pre-Columbian people but a complex mosaic of societies linked by networks of communication, trade, alliance, and probably warfare. Beginning 3000 to 5000 years ago, Erickson has written, these cultures erected “thousands of linear kilometers of artificial earthen causeways and canals, … large urban settlements, and intensive farming systems.” For reasons that are still not completely understood, the whole social network unraveled about the time of Columbus or soon after. Smallpox may well have visited the area—many researchers think that an epidemic of the disease greatly weakened the nearby Incan empire in about 1525. In addition, Meggers believes that the Beni, like the rest of Amazonia, was subject to catastrophic droughts.

    Erickson's team and local farmers erected their own raised fields to see how they might have worked. They concluded that the original inhabitants of the Beni probably employed traditional agriculture, growing beans, squash, sweet potatoes, and manioc on raised fields; agroforestry, planting groves of palm, nut, and fruit trees; and—perhaps surprisingly—aquaculture. Around the causeways in a northeastern region of the Beni known as Baures, Erickson says, run long, low, zigzag earthen walls that stretch for as much as 3 to 4 kilometers. The structures, he believes, were fish weirs, used when the rainy season covered the savanna with up to half a meter of standing water. Narrow channels up to 3 meters long open at angles in the zigzag. There, woven nets could be used to harvest fish and shellfish, Erickson says. The openings also funneled fish into artificial ponds as much as 30 meters across. In addition, the weirs are piled high with shells from apple snails (the edible gastropod genus Pomacea), possibly discarded after meals. The structures persist, although no one maintains them any longer; even today, the ponds pullulate with fish during the dry season. “They converted the savanna into huge fish farms,” says Erickson. “When you see the weirs radiating out from the causeways, I don't think there's any doubt of the intentionality.”

    Archaeology wars

    Others strongly disagree, in terms that mirror archaeology's long-standing disputes about Amazonia. In influential books and articles, Meggers and her husband, the late Clifford Evans, argued that despite its rich flora, the river basin's thin, acidic soils can't hold enough nutrients to permit sustained, intensive agriculture. And that means big, complex societies—which inevitably depend on agriculture—cannot long exist in Amazonia. Indeed, Meggers once proposed that Amazonian villages could contain no more than 1000 inhabitants before collapsing. “We call these cultures ‘primitive,’” she says of contemporary indigenous groups, which are some of the least technologically advanced in the world. “But they are actually remarkable accommodations to severe environmental limits. They show us what's possible there.”

    When researchers claim that large, complex societies existed in Amazonia, she says, it shows only that “there's a lot of tricky environmental stuff that most archaeologists either ignore or don't know about.” Because tropical lands are washed by frequent, heavy rains, she says, the traces of human occupation are flushed through the soil rather than being deposited in neat layers. Thus a place that was intermittently occupied by a few people can seem to have been settled permanently for long periods—the layers are smeared out. “The climate hides evidence of disoccupation,” she says. “The charcoal samples get displaced. There's a whole list of pitfalls and problems.”

    In the early 1980s, Bernard Dougherty and Horacio Calandra, two Argentine archaeologists backed by the Smithsonian, excavated several Beni lomas similar to Ibibate, though smaller. They concluded that the mounds were “not difficult to ascribe” to natural forces, especially “fluvial activity.” In their view, the causeways and raised fields of the Llanos de Mojos were probably created by a higher culture, perhaps from the Andes, which set up short-lived colonies that winked out under ecological pressure. “It seems that here, as in other parts of the world, the environment had the winning ace from the beginning,” Calandra and Dougherty wrote in 1984. In his dissertation, Langstroth argued, in parallel, that the isolated forests were not created by humans. “They were created by fragmentation and erosion of natural levees,” he says. “It sounds nice to give people credit for doing wonderful things, but the evidence isn't there.”

    Erickson's critics have also pointed out that structures like lomas, causeways, and raised fields require sustained mass labor, which in turn requires the coercive, centralized authority and hierarchical division of labor characteristic of state-level societies. Yet in lowland Amazonia, as Erickson concedes, there is “no good historic or ethnographic evidence” for such vertically organized states.

    Erickson has a different explanation: The earthworks, he suggests, were erected by “heterarchical” societies: groups of communities, loosely bound by shifting horizontal links through kinship, alliances, and informal associations. “There are some people working in South America who take a look at massive complexes of raised fields and say, ‘This has to be organized by a complex polity,’” reports Peter Stahl, an anthropologist at the State University of New York, Binghamton. “Whereas Clark [Erickson] says, ‘No, this is the accumulated landscape capital of generations of farmers who built it more or less on their own.’”

    Like Erickson, Roosevelt believes that sophisticated pre-Hispanic cultures occupied the middle and lower Amazon areas she has studied. With abundant fruit, nuts, edible palm, and fish, she says, river-basin peoples “had lots of options that people in [less naturally rich] places like central Mexico didn't have—they could always run away and do what they wanted.” The result, in her view, was “much less coercive” societies—“more like epic chiefdoms, where the leaders sponsor buildings and ceremonies”—somewhat like the wealthy, relatively relaxed Indian cultures in the Pacific Northwest and California. “And we're still learning,” she says, “about how they shaped this wonderful landscape they bequeathed us.”

    Researchers who deny the importance of the pre-Hispanic Beni cultures, Erickson explains, have been misled by “archaeology's traditional fixation on individual sites.” The traditional method of digging individual sites and measuring their contents is unlikely to produce clear data, Erickson says, for the very reasons Meggers cites: The area's heavy rainfall mixes up sedimentary layers, and the local practice of heaping up earth to create mounds and causeways further jumbles the archaeological record. So, he argues, traditional site excavation must give way to a study of the landscape as a whole—“treating the landscape like an artifact, as if it were a piece of pottery.” Such “landscape archaeology” uses nontraditional tools, including aerial photography, radar imagery, and multispectral satellite imagery, to prepare digital maps of large areas. “My main critique of the site concept is that it implicitly puts edges around each site. But here in the Beni, the ‘sites’ go on forever—the whole landscape has been organized and designed.”

    A flight in a small plane over the area makes Erickson's meaning clear. “This group of islands is connected with that one, but not those,” he says, shouting over the noise of the propellers. “There's a relationship there. … The raised fields are all aligned in a north-south direction. The landscape is telling us something.”

    Ecological adaptation

    Erickson and others argue that the Beni mound builders began a process of ecological change in the region that continues to this day. Balée, for example, says the Beni, in his view, was “not favorable for well-drained tropical forests until after people—deliberately or not—made it favorable for them” by raising the mounds above the floodwaters and enriching the soils by burning, mulching, and depositing wastes. After the original inhabitants of the lomas disappeared 300 to 600 years ago, the mounds were presumably colonized by forest. When the Sirionó arrived on the scene—Balée believes, on linguistic evidence, that they emigrated to the Beni about 3 centuries ago, probably from the south—they altered the composition of these forests to suit themselves, creating what Balée calls “artifactual forests.”

    As evidence, Balée points to one of the most common tree genera on the loma: Sorocea, which is used by the Sirionó to make beer. In the Beni, Sorocea is found only on the mounds, not in the surrounding land with standing water, which to Balée is “strong evidence” that people brought it to the lomas. Similarly, the spiny palm (Astrocaryum murumuru), which has many indigenous uses, is much more common on the lomas than elsewhere—“there's 112 of these here,” Balée says at Ibibate, “as opposed to something like 15” in an equivalent nonmound area.

    “There is more forest in the Llanos de Mojos because of people in pre-Hispanic times than in spite of them,” Balée says. To him, this indicates “that there is no necessary incompatibility between human use and biodiversity in the tropics,” and he hopes that conservationists, who sometimes view human actions as a priori destructive, will not seek to curtail the Indians' freedom.

    Active efforts are being made to protect the Beni and its remaining indigenous peoples from overdevelopment. After some hesitation, the Bolivian government has established more than a dozen reservation-like areas for Indian groups, although in some cases they provide little actual protection. Partially overlapping the indigenous areas for the Baures and Itonama peoples—the two easternmost reserves—is a proposed Kenneth Lee Scientific Reserve, named after the U.S. petroleum geologist whose vigorous advocacy of the Beni inspired many researchers, Erickson among them. (Lee died in 1997.) The Centro de Investigación y Documentación para el Desarrollo del Beni, a Trinidad-based nonprofit organization that seeks to develop the area in ways that would benefit indigenous groups, favors the plan. Meanwhile, some environmental groups would like UNESCO to create a World Heritage Site in the eastern Beni. There are already three such reserves in Bolivia, though none in the Llanos de Mojos. Presumably, the first priority in such a management scheme would be conservation—a stance that worries Denevan.

    “The Indians created the environment we're trying to protect,” he says. “They should get to stay there while we're learning what they did.”

  10. ARCHAEOLOGY

    The Good Earth: Did People Improve the Amazon Basin?

    1. Charles C. Mann

    The debate over the existence of a major prehistoric society in the Beni area of Bolivia (see main text) is tied to a broader dispute over whether the Amazon Basin has ever been able to support big, complex cultures. That dispute centers largely on soil quality. Despite its rich flora, Amazonia has many thin, aluminum-rich soils that can't hold nutrients and are toxic to crucial soil bacteria. Societies that try long-term farming, say Smithsonian archaeologist Betty J. Meggers and others, will destroy the soil completely—and their resource base along with it. But evidence has gradually accumulated that the picture of the Amazon as a “counterfeit paradise,” to use Meggers's phrase, may be overly simple.

    Amazonia is usually divided into the várzea, or floodplain, which occupies perhaps 2% of the basin's 7 million square kilometers, and the terra firme, the never-flooded uplands that comprise everything else. (Oddly, the Beni counts as uplands because it's flooded by rain, not river water.) According to Nigel J. H. Smith, a geographer at the University of Florida, Gainesville, “everyone agrees” that much of the várzea is fertile. What's in question is the fertility of the uplands. For more than 150 years, says Smith, individual researchers have reported that the terra firme contained pockets of good land—in particular the terra preta do indio (Indian black earth) often found beneath ancient indigenous settlements. In 1980, Smith summarized the evidence, including his own discoveries, for the prevalence of upland terra preta. “I got two reprint requests for that article,” he says, laughing. “Nobody was ready to hear it.”

    One reason for the neglect, according to Emilio F. Moran, an anthropologist at the University of Indiana, Bloomington, is what he calls “the problem of scale.” Three-quarters of the upland soils are indeed poor, he says. As a result, large-scale maps correctly show the basin as a wash of impoverished land. But on a smaller scale, Moran says, the land is dotted with patches of terra preta. “Even if it only covers 10% of the terra firme,” he says, “the Amazon is so big that 10% represents an enormous resource base. It's bigger than France.”

    The 10% figure, Moran says, is just a guess. Fewer than 1000 soil samples from the Amazon have ever been analyzed, according to William I. Woods, a geographer at Southern Illinois University in Edwardsville. Last year, Woods and Joseph I. McCann of the New School University in New York City published their study of the soils along the Tapajós River, a major tributary of the middle Amazon. They found scores of black-earth sites ranging from 0.5 to 120 hectares, most of which were still in use by local farmers. Indeed, Woods and McCann believe that indigenous agriculture, far from destroying the soil, actually improved it.

    In the past, archaeologists usually argued that terra preta represented ancient deposits of volcanic ash or former pond bottoms. Based on chemical analyses—and the constant presence of pottery—most researchers now believe that the black earth is created from old middens (deposits of waste). This explanation is incomplete, Woods and McCann say. They distinguish between terra preta proper, which they define as the soil directly around human settlements, and what they call “terra mulatta,” slightly lighter soils that surround terra preta and often cover areas 10 times larger. The terra preta is the remains of ancient middens; the terra mulatta is soil used for agriculture—soil that has been deliberately altered by mixing with wood ash.

    Farmers burned off the forest cover of their fields, Woods explains, then tilled in the cinders. The ash reduces the acidity of the soil, which in turn reduces the activity of the aluminum ions, fostering microbial growth. “In addition,” he says, the ash “greatly increases the nutrient-retention capacity.”

    “I can't tell you how much of the Amazon Basin has been changed,” Woods says, “but I can tell you that enormous areas have been modified, which implies a lot of people doing it.” Woods would not be surprised, he says, if Amazonia turned out to have about the same percentage of excellent arable land as, say, the United States. Smith agrees: “The soils were a constraint, but people overcame them. Amazonia may have been a counterfeit paradise to start with, but it sure doesn't sound like it was one when they were finished with it.”

  11. PLANT BIOTECHNOLOGY

    Consumer Power Heralds Hard Times for Researchers

    1. Lone Frank*
    1. Lone Frank writes from Copenhagen, Denmark.

    Since the European public became concerned about transgenic food, researchers have been hit by the fallout: reduced funding from governments and industry

    The consumer-led backlash in Europe against genetically modified crops has forced some of the world's major players in agricultural biotech, most notably Monsanto, to beat a retreat. But the multinational behemoths are not the only ones taking a hit: Academic researchers across Europe are now becoming victims. Europe could see an exodus of plant biotech talent unless politicians “face up to their role as driving forces in society and send some clear signals as to their intentions with respect to this technology,” says Claus Christiansen, research director of the Danish food giant Danisco.

    The once-hot field has been cooling off for a few years, European plant biotechnologists say, since they began to sense that national research agencies were losing enthusiasm for their work. Industry too began to scale back its own research programs as well as collaborations with academic groups. But now the alarm bells are really ringing. Plant biotech fared poorly in the first round of grants in the $17.6 billion Fifth Framework Programme (FP5), the latest 5-year European Union (E.U.) effort to support cross-border R&D collaborations. Statistics from a researchers' umbrella organization, the European Plant Biotechnology Network (EPBN), suggest that in the various funding categories open to plant biotech proposals, only 3% to 10% of applications succeeded, compared with 10% to 30% in the previous Framework Programme.

    Across the whole E.U., FP5 grants are spread pretty thinly, accounting for only about 5% of total public research funding, but they are increasingly important as catalysts. According to Oxford University's head of plant sciences, Christopher Leaver, E.U. funding is crucial in creating networks between research centers in different countries and for recruiting and training young scientists internationally.

    One much cited casualty of FP5 is the “yellow rice” project headed by Peter Beyer of the University of Freiburg in Germany and Ingo Potrykus of the Swiss Federal Institute of Technology in Zurich. With much fanfare, the E.U. announced last year that with FP4 funding the team had genetically engineered a rice strain to produce _-carotene, the precursor of vitamin A. The scientific community and media hailed this as a triumph for plant biotechnology and raised hopes for battling vitamin A deficiency in the Third World. Despite huge interest from developing countries and additional support from overseas funding bodies, when the group applied for FP5 funds mainly to develop hardier strains that could be grown in the field, they were turned down. Potrykus interprets the cold shoulder from FP5 administrators in Brussels as “a reaction to the political climate in Europe with its strong negative feelings against GMOs [genetically modified organisms].”

    E.U. officials dismiss the idea of a conspiracy against transgenic plant research. “There are no grounds for this rumor,” says Bruno Hansen, director of FP5's Quality of Life program committee, which oversees most plant biotech funding. Still, other officials concede that plant biotech faces more hurdles within FP5 than in previous programs. The explicit aims of the Framework programs have always been to increase the competitiveness of European industry and support other E.U. goals, but areas of basic research thought important to industry, such as biotechnology, were widely supported. Now every grant must have an explicit payoff for European industry or E.U. socioeconomic efforts, making it difficult for basic research to find a niche. Under FP5, there is no longer a separate budget for plant biotechnology, so “plant projects, which are generally slow to deliver, are handicapped in competition with other organisms,” says EPBN project manager Karin Meztlaff. Holger Rasmussen of the Danish Ministry of Research concedes that with Framework's new focus, scientists “have difficulties getting funding for less applied projects.”

    As if troubles at the pan-European level weren't enough, scientists worry that national funding agencies are also tuned in to public fears about transgenic foods. In the Netherlands, says plant geneticist Richard Visser of Wageningen University, shrinking public funds for fundamental research and industry's reluctance to support plant biotech projects are squeezing the field from both sides. The past year has been hard for Danish plant research too. A government-funded plant biotech program was not renewed when it ended last year, and the major industry research sponsor—Danisco, a food and ingredient company—has virtually pulled out of plant biotechnology. Many observers interpret this as a response to pressure at last year's stockholders meeting not to invest in GMOs. Across Europe, industry is battening down the hatches. Klaus H. Nielsen, director of research at Danish seed company DLF-Trifolium, says, “Apart from a few initiatives, everybody is waiting for the negative atmosphere to blow over.”

    But with the biotech industry becoming increasingly global, large corporations always have the option to move their research efforts, and collaborations with academic researchers, to parts of the world where conditions are more favorable. “We are following agrobiotech development closely, and it would be very sad if Europe were affected by the current GMO opposition and lost its science base,” says Nigel Pool, director of external affairs with the Anglo-Swedish drug and biotech giant AstraZeneca. Researchers point out that European companies are already making significant investments overseas, such as the Swiss agrobiotech giant Novartis, which has put $600 million into a center for plant research in San Diego and is heavily supporting a center for plant genomics at the University of California, Berkeley.

    So should European researchers keep their heads down and wait for public antipathy for their work to die down? Plant geneticist Jonathan Jones of the John Innes Centre near Norwich, U.K., predicts that “in the long run, European plant science will lose out if the current development continues. The most talented scientists will have to move elsewhere for opportunities, and Europe will see fewer start-up companies in the plant biotechnology sector.” Oxford's Leaver adds that “recruiting top-quality workers for plant research at the postgraduate and postdoctoral level is a major problem in the U.K.,” where concerns about GM foods run particularly deep. And in Germany, plant geneticist Heinz Saeidler of the Max Planck Institute for plant propagation research in Cologne says he is getting fewer students, who see poor career prospects in such an unpopular field.

    Most researchers believe the public will come to embrace transgenic crops, especially after future varieties show traits that genuinely benefit consumers, such as increased nutritional value or the elimination of natural allergens. But by then it may be too late for European researchers. “The worst case scenario is Europe taking a break to think about things,” warns Nielsen. “By not concentrating on this research now we risk having to import the future products of plant biotechnology from elsewhere.”

  12. NEUROSCIENCE

    Cold Numbers Unmake the Quantum Mind

    1. Charles Seife

    Calculations show that collapsing wave functions in the scaffolding of the brain can't explain the mystery of consciousness

    Sir Roger Penrose is incoherent, and Max Tegmark says he can prove it. According to Tegmark's calculations, the neurons in Penrose's brain are too warm to be performing quantum computations—a key requirement for Penrose's favorite theory of consciousness.

    Penrose, the Oxford mathematician famous for his work on tiling the plane with various shapes, is one of a handful of scientists who believe that the ephemeral nature of consciousness suggests a quantum process. In the realm of the extremely small, an object with a property such as polarization or spin may exist in any of a number of quantum states. Or, bizarrely, it may inhabit several quantum states at once, a property called superposition. A quantum superposition is extremely fragile. If an atom in such a state interacts with its environment—by being bumped or prodded by nearby atoms, for instance—its waveform can “collapse,” ending the superposition by forcing the atom to commit to one of its possible states.

    To some investigators, this process of coherence and collapse seems strikingly similar to what goes on in the mind. Multiple ideas flit around below the threshold of awareness, then somehow solidify and wind up at the front of our consciousness. Quantum consciousness aficionados suspect that the analogy might be more than a coincidence. Eleven years ago, Penrose publicly joined their number, speculating in a popular book called The Emperor's New Mind that the brain might be acting like a quantum computer.

    “Between the preconscious and conscious transition, there's no obvious threshold,” says Penrose's sometime collaborator Stuart Hameroff, an anesthesiologist at the University of Arizona in Tucson. Ideas start out in superposition in the preconscious and then wind up in the conscious mind as the superposition ends and the waveform collapses. “The collapse is where consciousness comes in,” says Hameroff.

    But what exactly is collapsing? From his studies of neurophysiology, Hameroff knew of a possible seat for the quantum nature: “microtubules,” tiny tubes constructed out of a protein called tubulin that make up the skeletons of our cells, including neurons. Tubulin proteins can take at least two different shapes—extended and contracted—so, in theory, they might be able to take both states at once. If so, then an individual tubulin protein might affect its neighbors' quantum states, which in turn affect their neighbors'—and so forth, throughout the brain. In the 1990s, Penrose and Hameroff showed how such a tubulin-based quantum messaging system could act like a huge quantum computer that might be the seat of our conscious experience.

    The idea attracted a few physicists, some consciousness researchers, and a large number of mystics. Quantum physicists, however, largely ignored it as too speculative to be worth testing with numerical calculations. Now Tegmark, a physicist at the University of Pennsylvania, has done the numbers. In the February issue of Physical Review E, Tegmark presents calculations showing just what a terrible environment the brain is for quantum computation.

    Combining data about the brain's temperature, the sizes of various proposed quantum objects, and disturbances caused by such things as nearby ions, Tegmark calculated how long microtubules and other possible quantum computers within the brain might remain in superposition before they decohere. His answer: The superpositions disappear in 10−13 to 10−20 seconds. Because the fastest neurons tend to operate on a time scale of 10−3 seconds or so, Tegmark concludes that whatever the brain's quantum nature is, it decoheres far too rapidly for the neurons to take advantage of it.

    “If our neurons have anything at all to do with our thinking, if all these electrical firings correspond in any way to our thought patterns, we are not quantum computers,” says Tegmark. The problem is that the matter inside our skulls is warm and ever-changing on an atomic scale, an environment that dooms any nascent quantum computation before it can affect our thought patterns. For quantum effects to become important, the brain would have to be a tiny fraction of a degree above absolute zero.

    Hameroff is unconvinced. “It's obvious that thermal decoherence is going to be a problem, but I think biology has ways around it,” he says. Water molecules in the brain tissue, for instance, might keep tubulin coherent by shielding the microtubules from their environment. “In back-of-the-envelope calculations, I made up those 13 orders of magnitude pretty easily.”

    Some members of the quantum-consciousness community, however, concede that Tegmark has landed a body blow on Penrose-Hameroff-type views of the brain. “Those models are severely impacted by these results,” says physicist Henry Stapp of Lawrence Berkeley National Laboratory in California. (Stapp's own theory of quantum consciousness, he says, is unaffected by Tegmark's arguments.)

    Physicists outside the fray, such as IBM's John Smolin, say the calculations confirm what they had suspected all along. “We're not working with a brain that's near absolute zero. It's reasonably unlikely that the brain evolved quantum behavior,” he says. Smolin adds: “I'm conscientiously staying away” from the debate.

  13. MATHEMATICS

    Fermat's Last Theorem's First Cousin

    1. Dana Mackenzie

    A proof of the Langlands conjecture for function fields answers a question that has puzzled mathematicians for over 3 decades

    In January 1967, a 30-year-old Princeton mathematics professor named Robert Langlands wrote to André Weil, the dean of the world's number theorists, asking for his opinion about two new conjectures. “If you are willing to read [my letter] as pure speculation I would appreciate that,” wrote Langlands; “if not—I'm sure you have a waste basket.”

    Weil never wrote back, but Langlands's letter turned out to be a Rosetta stone linking two different branches of mathematics. He posited that there was an equivalence—rather like a French-English dictionary—between Galois representations and automorphic forms. The former describe the intricate relationships among the solutions to equations studied in number theory. The latter are highly symmetric functions. The most familiar examples are the sine and cosine functions, which are periodic, or invariant under horizontal shifts. Such shifts (for example, “move left 2π units” or “move right 4π units”) give the same result when performed in any order. The elementary symmetry of the sine and cosine functions is as boring to mathematicians as a test pattern. But Langlands foresaw that the future of number theory lay in understanding functions with more exotic, order-sensitive kinds of periodicity—functions with the infinite complexity of fractals.

    For 30 years, Langlands's questions—which are often called the “Langlands program” because of their many ramifications—have been a driving force in number theory. The program has led to two Fields medals (widely considered the equivalent of the Nobel Prize for mathematics) for other mathematicians. Perhaps the greatest mathematical achievement of the 20th century, Andrew Wiles's 1994 proof of Fermat's Last Theorem, can also be viewed as the completion of a small part of the Langlands program. “The Langlands program ties together theories that are a priori very different and very distant from one another,” says Laurent Lafforgue, a number theorist at the Université de Paris-Sud.

    This fall, thanks to Lafforgue, another piece of the program finally fell into place. In November, Lafforgue gave the first U.S. presentation of his proof of the “Langlands conjecture for function fields” in a series of lectures at the Institute for Advanced Study in Princeton, New Jersey. A 300-page handwritten version of Lafforgue's proof has been circulating among mathematicians since the summer, but it has not yet been submitted for publication. Nevertheless, the experts seem quite confident that it will hold up. “I'm sure it's a contender for the Fields medal,” says Peter Sarnak, a number theorist at Princeton University. Says Langlands, who attended the lectures, “There's nothing suspicious about his argument. He was a man who knew exactly what he was talking about.”

    The “fields” that Lafforgue refers to have nothing to do with fields in physics (or, for that matter, agriculture). Mathematicians use the word “field” to denote any algebraic structure consisting of objects, or elements, that can be added, subtracted, multiplied, and divided according to the rules that govern real numbers. In one large category of fields, number fields, the objects are ordinary rational numbers (fractions), or real numbers, or complex numbers. Many number theorists deal only with these fields, where the classical questions of number theory (such as Fermat's Last Theorem) first arose.

    However, there are two other types of fields, each distinctive enough in its properties to attract its own coterie of experts. Perhaps the most bizarre are local fields such as the 7-adic numbers, where live such creatures as the number 1 + 7 + 72 + 73 + … These numbers are forbidden in the universe of real numbers because they can become infinitely large. Finally, there are the function fields, whose elements are polynomials or quotients of polynomials—for example, (x2 - 3x + 1)/(x + 2). Although local fields and function fields are less familiar than number fields, they often are easier to study. Lafforgue's work proves Langlands's conjectures only in the context of function fields. In 1998, three other mathematicians proved them for local fields as well. That leaves only the central problem of number fields unresolved. “I don't think it will take a miracle,” says Langlands. “There's a hump we've got to get over, an insight that's not out there yet.”

    Historically, Langlands's conjectures arose out of an effort to find very general versions of what number theorists call reciprocity laws—patterns governing how whole numbers can be broken down into sums of products of other whole numbers. (The term is a bit of a misnomer, as reciprocity laws have nothing particularly to do with reciprocals.) These laws date back hundreds of years. In the 17th century, Pierre de Fermat enjoyed solving such questions as this: Which prime numbers can be represented as a sum of two squares? For example, 5 is 22 + 12; but 7 cannot be written as a sum of squares. He discovered a simple pattern, whose reasons were nevertheless mysterious: An odd prime number can be written as a sum of two squares if it is 1 greater than a multiple of 4, and not if it is 3 greater than a multiple of 4. Thus the pattern is periodic in the same sense that the sine and cosine functions are. As far as representations as sums of squares are concerned, a shift of the whole prime number system by four units to the left would be invisible.

    Over the centuries, mathematicians discovered a host of other reciprocity laws. The story seemed to reach a glorious conclusion in 1927, when Emil Artin proved a single reciprocity law that encompassed all the others. Although the number theory behind his work was profound, the geometry was rather banal—the “symmetry groups,” or sets of periodicities involved, were one-dimensional, like the periodicities of the sine and cosine functions. More complicated patterns eluded mathematicians until 1967, when Langlands's link to automorphic forms showed mathematicians how they could bring to bear the theory of n-dimensional matrices (or n-by-n tables of numbers). A number, Langlands realized, is just a 1-by-1 matrix in disguise. Just as shifts can be represented by a single number or 1-by-1 matrix—the distance shifted—he hypothesized that the transformations behind more general reciprocity laws could be represented by matrices. The link has remained conjectural, but the confirmation of one special case led to disproportionately large consequences. The seed of Andrew Wiles's monumental work on Fermat's Last Theorem was his proof of Langlands's conjecture for 2-by-2 matrices whose entries are all 0, 1, or 2.

    Lafforgue's tour de force is unlikely to have such dramatic consequences, because function fields lack the éclat of number fields and Fermat's Last Theorem. However, other mathematicians say that its significance will likely become apparent in time. “Lafforgue has proved that two very different-looking things are the same,” says Nicholas Katz, an algebraic geometer at Princeton University. “When you do that, it's almost always the case that there are some properties that are very easy to see one way, and incredibly obscure the other way. … It's too soon to predict exactly how it's going to work, but I feel strongly that it's very important.”

  14. ECOLOGY

    How Climate Change Alters Rhythms of the Wild

    1. Bernice Wuethrich*
    1. Bernice Wuethrich writes from Washington, D.C.

    The more scientists look, the more connections they see between shifts in climate and changes in animal behavior and populations

    Each year for 31 years, biologist Jerram Brown has trekked into the Chiricahua Mountains of southern Arizona to chronicle the rites of spring for a population of Mexican jays. Brown adheres to his own ritual: The biologist from the State University of New York, Albany, notes on which date the females lay their first clutch, then several weeks later he shinnies up 15-meter-tall Chihuahua pines to band each and every chick. His perseverance has paid off with an intriguing observation: The jays are laying their eggs earlier and earlier each season. By 1998, the first eggs of the season arrived 10 days earlier than in 1971.

    Brown blames global warming for turning the hands forward on the jays' reproductive clock. Although Arizona hasn't necessarily gotten hotter, it has grown less cool. In the months leading up to the breeding season, Brown found, average daily minimum temperatures have nudged up 2.7 degrees Celsius in 27 years. A narrower temperature range probably encourages earlier breeding by allowing birds to conserve energy on cold nights, when they can burn off about 10% of their weight just to stay warm, Brown says. The warmer air may also roust insects earlier, which would likewise provide extra calories for females to funnel into the energetic business of egg production. Strengthening the case against warming, Brown says, is the fact that many other species in the Northern Hemisphere, from birds to frogs, are also breeding earlier than they were years ago. “While no one study can prove that earlier breeding is caused by global warming,” he says, “it all fits in.”

    For more than 2 decades, climate modelers have warned that global warming may transform our environment by pushing corn belts north, expanding deserts, and melting ice caps. Now biologists are getting in on the action, compiling an impressive array of data suggesting that climate changes big and small can have profound effects on species. Climate's fingerprints are turning up in observations compiled over years and decades.

    The sheer complexity of ecosystems makes biologists reluctant to start predicting the fate of individual species based on various climate-change scenarios. But with some models forecasting that average global temperatures could rise as much as 4.6 degrees Celsius in the coming century, the new observations “give us a handle to think about where things will be in 2100,” says biologist Camille Parmesan of the University of Texas, Austin.

    Dippers take a dive. The latest observation of a species' response to climate change involves Norway's national bird, the dipper. On page 854 of this issue, a team led by Bernt-Erik Sæther and Jarle Tufto of the Norwegian University of Science and Technology in Trondheim reports that while the number of dippers in a population in southern Norway fluctuated between 1978 and 1997, it followed an upward trajectory. The trend—based on an analysis of more than 20 years of observations by amateur bird watchers—was closely associated with the gentle touch of an atmospheric pressure system called the North Atlantic Oscillation (NAO) and the milder winter temperatures it brought.

    The NAO, which embraces much of the Northern Hemisphere, delivers warm, wet winters to northern Europe during its high phase. (When it flips to low gear, bitter cold usually sets in.) For much of the past 3 decades, the high phase has dominated, and for the dipper, “a warm year is a good year,” Sæther says. Because the bird dives for its food on stream bottoms, it has little to eat if streams ice over. The researchers found that the bird's ranks swelled after warm years, thanks to increased immigration and a higher birth rate in the local population. A long-term warming of 2.5 degrees Celsius, Sæther's team estimates, should boost dipper numbers by 58%.

    The team's mathematical model, which takes into account random population fluctuations and temperature changes, can be applied to other species as well, says Peter Kareiva, a biologist with the U.S. National Oceanic and Atmospheric Administration in Seattle. Unlike previous models, Sæther's teases apart the effects of climate change from those of density dependence, a phenomenon in which mortality rates tend to rise, and birth rates fall, as a population's size increases.

    Also in tune with the NAO, it would appear, are grazing mammals. Eric Post and Nils Chr. Stenseth of the University of Oslo in Norway analyzed 15 years of data on northern mammals. They found that 9 of 11 ungulate populations—including caribou, musk ox, moose, feral goats, and Soay sheep—declined following warm NAO winters. But the effects varied by location. In maritime areas, the survival rates of Soay sheep and feral goats improved during mild winters, spurring increased competition for food and population declines the following spring. Farther from the coast, high NAO years were not only warm but extra snowy, making it harder for the animals to forage and making them easier prey. Thus it is no surprise that they fared poorly during NAO highs, says Post, whose team's results appear in the June 1999 issue of Ecology.

    That the NAO influences so many species “throws up a red flag,” says Post, who estimates that about 5 million caribou and reindeer, 16 million white-tailed deer, and 2 million moose now graze in high latitudes. But the NAO could be a harbinger of grander changes. “With global warming we might see declines of some large mammals throughout the Northern Hemisphere,” says Post, who points out that many northern species perished during the last major episode of global warming, at the end of the last ice age.

    Butterflies on the wing. Whereas extreme climate, like extreme sports, weeds out the meek, a gradual warming seems to weave a more subtle spell on species. Warming sends butterflies, for instance, fluttering into terra nova. In the last century, Europe has warmed by 0.8 degrees Celsius, and its isotherms (bands of average temperature) have drifted north—roughly in sync with the shifting ranges of many butterflies.

    View this table:

    Parmesan analyzed distribution patterns of 57 nonmigratory butterfly species across Europe. In the last century, about two-thirds of the species have shifted their ranges northward as much as 240 kilometers, she reported in the 10 June 1999 issue of Nature. “We ruled out all other obvious factors, such as habitat change, that could alter distributions,” Parmesan says. “The only factor that correlated was climate.” New populations are popping up in regions such as Finland and Sweden that were previously too cold for comfort, she says.

    Although a shifting range suits some populations fine, for others, Parmesan says, it means moving “out of good habitat into fragmented landscapes where they can't survive.” Some European butterflies are declining as a result. The same is true in North America, where the Quino checkerspot butterfly has mostly abandoned the southern edge of its range in Mexico. There, warming temperatures cause larvae to hatch early and their snapdragon host plants to bloom early. But the plants are also drying and dying sooner, starving caterpillars before they are able to wait out the winter in their cocoons. Meanwhile, habitat in suitable regions farther north, where the butterfly thrived previously, has mostly been swallowed in the urban sprawl of Southern California.

    While Parmesan has tracked range shifts of closely related species across an entire continent, Alan Pounds, an ecologist at the Monteverde Cloud Forest Preserve in Costa Rica, has documented disturbing changes in three disparate groups—amphibians, reptiles, and birds—on a tropical mountain. Pounds and biologist Michael Fogden have correlated population extinctions in 20 of 50 frog species, as well as range shifts in all three groups, to a broad climatic pattern: more mist-free days. Clouds usually hug the upper reaches of the mountains, and their mists bring moisture even without rain. The increasing frequency of dry days corresponds to rising Pacific Ocean surface temperatures, Pounds reported in the 15 April 1999 issue of Nature. The warmer ocean warms the air, which ultimately pushes the cloud ceiling higher up the mountain.

    “We never would have predicted that the climate change we've seen up till now would have caused the collapse of the amphibian fauna,” Pounds says. The higher clouds, he believes, triggered several chains of ecological events—including one that culminated in an outbreak of chytrid fungus, a frog pathogen—that contributed to extinctions.

    Like a football game without any huddles, a change in how key species interact can destabilize, or even bring down, an entire ecosystem. “If interactions are very sensitive to temperature, then small shifts could have rapid effects, cascading through the community,” says community ecologist Eric Sanford of Stanford University. To test this idea, Sanford went tide pooling. He worked with a well-known system: a rocky intertidal habitat ruled by the starfish predator Pisaster ochraceus. Along the Pacific beaches of Oregon and Washington states, P. ochraceus feasts on mussels, its prime competitor for space. In the starfish's absence, the mussels take over, literally crushing all other invertebrates beneath them, until the only species remaining is the mussel itself.

    Observing eating habits of the starfish as colder water upwelled and subsided, Sanford noted that a cooling of 3 degrees was enough to transform P. ochraceus from a glutton into a finicky eater. This suggests that a change in upwelling patterns along the West Coast—as some climate models predict—could decimate communities by altering one key species interaction, says Sanford.

    The findings pouring in could have huge implications for conservation. “Strategies for protecting land or species could be thwarted by substantial climate change,” Kareiva says. Cordoning off a preserve for an endangered species may work in the short term, but climate change could render the habitat unsuitable for the target species. Coping with climate change, Kareiva says, will mean maintaining genetically diverse populations capable of adaptation.

    If you can't beat climate change, you may as well learn from it. “We can analyze [climate fluctuations] as if they are experiments and learn a lot about how ecological systems function,” Stenseth says. Like it or not, he says, the changes are “happening anyway.”

  15. AMERICAN ASTRONOMICAL SOCIETY MEETING

    New Focus on Cool Planets and Hot Gas in Atlanta

    1. Robert Irion

    ATLANTA—About 1700 members of the American Astronomical Society preceded the Super Bowl here last month for their 195th national meeting. Astronomers scored big with news about ubiquitous black holes and results from the Chandra X-ray Observatory (Science, 21 January, p. 411), but sessions on the Keck Observatory, planetary disks, and our galaxy's shroud of hot gas also drew notice.

    Sharp New Eyes for Keck II

    With their monstrous 10-meter mirrors, the twin Keck I and II Telescopes at Mauna Kea, Hawaii, already have a competitive edge over other observatories on the ground. That edge has now become sharper, thanks to technical wizardry that lets Keck II see through Earth's atmosphere with startling clarity.

    The wizardry is adaptive optics (AO), in which a thin mirror deforms rapidly to counteract the blurring effects of the continual sloshing of air above the telescope (Science, 19 November 1999, p. 1504). Astronomers have had good success with these complex systems at several telescopes, notably the 3.6-meter Canada-France-Hawaii Telescope atop Mauna Kea and the European Southern Observatory's 3.6-meter telescope at La Silla, Chile. Among the 8- to 10-meter Goliaths now dotting mountaintops, however, Keck is the first to use AO for scientific observations. “Keck's way out in front,” says astronomer Matt Mountain, director of the Gemini Observatory and its two 8.1-meter telescopes in Hawaii and Chile. “We think their results are spectacular.”

    Several speakers showed before-and-after images from Keck II to a captivated audience at the meeting. (An identical system will go online at Keck I by June.) Astronomer Claire Max of the Lawrence Livermore National Laboratory in Livermore, California, prompted the biggest collective exhales with her infrared images of various objects in the solar system, including Neptune and Titan, Saturn's largest moon. Bright spots in Neptune's atmosphere, previously seen from the ground merely as blobs, resolved into a large stormy patch and windy streaks that closely resemble those seen by Voyager 2 in 1989. A succession of such images will expose changes over time, Max says, perhaps unveiling the forces that drive the fierce weather patterns in Neptune's atmosphere.

    As for enigmatic Titan, Keck II now can penetrate the moon's thick layer of haze to see its surface within a narrow band of unabsorbed infrared light. The images reveal prominent dark blotches, which Max believes may represent “seas” of ethane and other hydrocarbons predicted to rain out from Titan's methane-rich atmosphere. A new instrument at Keck II, the Near Infrared Spectrometer, will enable Max and her colleagues to take spectra of these features and nail down their compositions more firmly.

    Keck engineer Scott Acton also displayed a dramatic image of Jupiter's moon Io. The AO team happened to observe Io on 26 November—soon after the Galileo spacecraft saw what may have been a “lava fountain” spewing from the moon's tortured surface (Science, 24 December 1999, p. 2436). The nearly edge-on view of the plume, combined with a similar view that night from NASA's Infrared Telescope Facility on Mauna Kea, should help planetary scientists narrow their estimates of its height and temperature.

    Keck II's new capabilities promise insights beyond the solar system as well. For example, astronomer Andrea Ghez of the University of California, Los Angeles, is using the system to track the rapid motions of stars near the suspected black hole at the center of the Milky Way galaxy. The unblurred view lets Ghez see twice as many stars in far less time—single exposures that last 90 seconds rather than many rapid snapshots that add up to 30 minutes or more. “It's helping us tremendously,” Ghez observes. Her team has begun to see the curvatures of the stars' orbits around the black hole, which should lead to much better estimates of its mass. Ghez also hopes that by monitoring the galactic center with AO for several years, she'll see evidence of gravitational lensing as the black hole distorts and amplifies the light from stars that pass behind it.

    The $7.4 million system does have limitations. Like most other AO efforts today, it works only for infrared light. The shorter wavelengths of optical light would require far more tiny pistons to flex the mirror than the 349 already in place at Keck II—technically feasible, perhaps, but hugely expensive. Further, the camera that senses the atmospheric distortions needs a lot of light. Astronomers must therefore look at bright objects or other objects next to a bright star, confining them to just a few percent of the sky. That will change by the end of the year when Keck engineers and Livermore laser specialists complete a “laser guide star” system, in which a tiny spot of laser light high in the atmosphere will enable astronomers to point the telescope nearly anywhere they choose. Other major observatories, such as Gemini, also will use the laser guide star approach for their AO systems.

    Keck II's early progress is a promising preview of such future efforts, says astronomer John Mather, project scientist for the Next Generation Space Telescope at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “Some of these images made my heart jump and my stomach leap,” Mather says. “I'm delighted to see adaptive optics working at last.”

    The FUSE of the Galaxy's Gas Circuit

    Superheated gas from legions of exploding stars envelops our Milky Way, according to the first results from a new NASA satellite. The findings appear to resolve a decades-long debate over one of the most fundamental processes in cosmic evolution: How do the galaxy's new stars inherit gas from their long-dead ancestors?

    The debate has simmered since 1956, when the late Princeton University astrophysicist Lyman Spitzer proposed that hot gas wraps the galaxy in a tenuous but energetic cocoon. Only a hot, invisible gas, he reasoned, would exert enough pressure to hold together the interstellar gas clouds that astronomers had spotted in the galaxy's ethereal halo, high above the flattened plane of the Milky Way.

    By the mid-1970s, astronomers believed the halo gas arose from one of two possible sources. Some proposed “galactic fountains” of hot gas spewing upward from pockets of many supernovas. Others favored a cooler gas shroud arising from a lower energy process: ionization of atoms by ultraviolet radiation from newborn stars. Until recently, however, nobody could get a clear view of the gas itself, so decisive evidence was lacking. Moreover, not all astronomers were convinced that the gas billowed as far from the Milky Way's plane as Spitzer thought.

    The new clues come from the Far Ultraviolet Spectroscopic Explorer, or FUSE. Launched in June 1999, FUSE stares at the light from distant bright objects, such as quasars. As this light arrows toward Earth, it pierces clouds of gas along the way. Atoms and molecules within the clouds absorb light at specific energies, leaving telltale dark imprints on the quasar's spectrum. The key ion that FUSE detected is oxygen VI, which can exist only at temperatures between 200,000º and 1,000,000ºC. Previous ultraviolet satellites had seen oxygen VI within the Milky Way's disk, but they lacked the sensitivity to detect it at great distances in the halo.

    Now, says astronomer Blair Savage of the University of Wisconsin, Madison, “we see evidence for hot gas in nearly every direction we look”—17 hits along 18 different lines of sight so far. The gas extends about 5000 to 10,000 light-years above the Milky Way's disk, Savage reports. (By comparison, the galaxy is about 100,000 light-years across.) The gas is patchy and remarkably thin: up to 10,000 times less dense than typical interstellar gas abundances of one atom per cubic centimeter.

    Oxygen VI ions are signposts of violent astrophysical collisions, which strip away five of the eight electrons in each atom. The concussive deaths of giant stars in supernovas produce the only blast waves strong enough to forge oxygen VI en masse, says astronomer Kenneth Sembach of The Johns Hopkins University in Baltimore, Maryland. As Sembach and his colleagues envision it, dozens of supernovas working together blow bubbles of hot gas. Pressure builds until the bubbles, hemmed in by resistant gas and dust in the galaxy's plane, blast away from the disk along the path of least resistance. “It's like a balloon that bursts at its weak spot,” Sembach says.

    FUSE thus has unveiled part of the long-suspected cycling of gas through the Milky Way, says astrophysicist J. Michael Shull of the University of Colorado, Boulder. After the galactic fountain streams upward, the gas cools and falls back onto the galaxy millions of years later to seed more generations of stars and planets. Each year, that cycle may process about 20 times as much gas as our sun contains, even though only one or two supernovas pop off in the Milky Way each century. Says Shull, “I think we've settled the debate: Supernovas drive an incredibly efficient engine of gas.”

    A Close Encounter at Beta Pictoris?

    The bright star Beta Pictoris is a perplexing sight. Sixty-three light-years from Earth, it floats in space wreathed in a huge veil of debris that astronomers view edge-on. Left to its own devices, the dusty disk should swirl symmetrically, like the saucers of UFO fame. Instead, it's longer and thinner on one side and warped near the middle, prompting some astronomers to claim that at least one giant planet must be plowing through the disk and knocking it off kilter (Science, 16 January 1998, p. 322). Now, a newly discovered chain of clumps in part of the disk suggests—at least according to one interpretation—that a different force may have struck: the gravitational pull of a passing star.

    The clumps surfaced during a comparison of a decade's worth of images from several observatories. A team led by astronomer Paul Kalas of the Space Telescope Science Institute in Baltimore, Maryland, digitally subtracted a smooth, ideal dust disk from the images. In each case, the astronomers saw seven otherwise hidden clumps along the long and thin side of the disk, but none on the shorter and fatter side. “This could be the cross section of an asymmetric ring system on a huge scale, many times the size of our solar system,” Kalas says.

    Kalas suspected that a star drifted past the disk recently and swept some of the dust into looping, elliptical orbits in its wake. To test his hypothesis, he called upon theorist John Larwood of Queen Mary and Westfield College in London to devise a computer simulation of the havoc that such an encounter would wreak. If a small star approached from below the disk and flew close to its edge, Larwood found, the star's gravity would fling dust particles into lopsided bands lasting about a million years before they merge back into the disk. Seen from the side, such bands would group into clumps like those in the telescope images of Beta Pictoris. A stellar flyby also would explain why the disk is so much larger than any other circumstellar shroud yet seen, Kalas adds: The interloper would have stretched the dust about twice as far into space as it ordinarily orbits.

    Colleagues find Kalas's scenario intriguing but unlikely. “Stars are so widely separated that those interactions are very rare unless you're in a cluster, which Beta Pic is not,” says astronomer Ben Zuckerman of the University of California, Los Angeles. A statistical calculation pins the chances of a random close encounter within the last million years at about 1 in 10,000, Kalas acknowledges. Undeterred, his team is scouring for the culprit in data from Hipparcos, a European satellite that charted the relative motions of thousands of stars. Several stars probably have wandered within a few light-years of Beta Pictoris, but the team has not yet spotted one that zipped by close enough to roil the disk so dramatically.

    Further, the innermost and densest parts of the disk—where Hubble sees the most pronounced warping—probably could not be perturbed by a passing star, says astronomer Sally Heap of NASA's Goddard Space Flight Center in Greenbelt, Maryland. She maintains that a planetary or brown dwarf companion is “by far the simplest explanation” of the tilt at the disk's heart.

    Even if Kalas and his colleagues can't prove their case, Zuckerman notes, spotting the string of clumps is a coup. “If it's really possible to resolve structures on such a small scale, it bodes well for future studies of planet-disk interactions,” he says. Soon, astronomers may interpret blobs and bands within dusty disks as certain imprints of newly formed worlds.

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