This month in Science Roundup:
Women's Health
Anti-HIV Antibodies Attack Self
A Winning Face?
Alarming Chickadee Calls
Ivory-Billed Woodpecker Returns
Biomass to Biofuel
Science in the Arab World
Economical Transport
Origins of Bronze-Age Glass
Optical Nanoantennas
Reassessing Earth's Interior
Earth, Ice, and Sea Level Rise
Women's Health
http://www.sciencemag.org/sciext/womenshealth/
Once neglected, studies of women's health are finally coming of age, due in large part to the efforts of the Women's Health Initiative (see related Editorial by V. Simon). In a collection of articles published with the 10 June 2005 issue, Science and its online companion sites explored the many dimensions of women's health. In a special section of Science, News and Review articles offered insights into female-male differences in areas such as drug metabolism, HIV/AIDS susceptibility, cardiovascular disease, and mental health -- and discussed conditions specific to women including endometriosis and preeclampsia (a circulatory disturbance between mother and fetus). Two Policy Forums debated the refusal by some pharmacists to dispense prescriptions for contraception, and a Book Review highlighted a recent volume on pregnancy loss by Science correspondent J. Cohen. The Signal Transduction Knowledge Environment focused on estrogen signaling as it relates to cancer and vascular health, as well as on signaling associated with infection by human papillomaviruses; articles in the Science of Aging Knowledge Environment explained how understanding male-female differences in longevity and the course of age-related diseases might improve health care for both sexes. Finally, Science's Next Wave offered perspectives from three women scientists who returned to work after illness and, through GrantsNet, a sampling of current funding opportunities for research on women's health.
Anti-HIV Antibodies Attack Self
A major obstacle in developing a vaccine against human immunodeficiency virus (HIV) is the difficulty of generating antibodies versatile enough to fight different strains of the virus. Rare human monoclonal antibodies that are broadly specific for HIV and can neutralize the virus do exist, but vaccine candidates have so far been unable to coax the body to produce them. In a Report in the 24 Jun 2005 Science (published online 28 April 2005), Haynes et al. ( http://www.sciencemag.org/cgi/content/short/308/5730/1906) offered an unexpected reason why. The researchers found that two of the rare antibodies react with another substance in the body called cardiolipin -- a phospholipid to which antibodies are formed in lupus and other autoimmune diseases. This means that the very features that make broadly neutralizing antibodies effective against HIV may also make them self-reactive, and as such, not tolerated by the immune system. An accompanying Perspective by G. J. Nabel ( http://www.sciencemag.org/cgi/content/short/308/5730/1878 ) discussed these and other recent finding about antibodies directed to a region of the HIV-1 envelope glycoprotein and their possible therapeutic utility.
Some say that first impressions are everything. They influence how we approach and react to others, and often lead us to make snap judgments about a person's character. In a Report in the 10 June 2005 Science, Todorov et al. ( http://www.sciencemag.org/cgi/content/short/308/5728/1623 ) demonstrated just how quickly first impressions are formed and what consequences they can have. Volunteers were asked to judge the relative competence of recent candidates for U.S. Congress races, based solely on 1-second view of the candidates' black-and-white head shots. Amazingly, these inferences, based solely on facial appearance and with no prior knowledge of the person, correctly predicted the election outcomes nearly 70% of the time. Moreover, the competence judgments were linearly related to the margin of victory. Inferences of other traits such as likability and trustworthiness did not prove to be accurate predictors. These findings suggest that that rapid unreflective trait judgments contribute to voting choices, which are assumed to be primarily based on rational, deliberative considerations. In an accompanying Perspective, L. A. Zebrowitz and J. M. Montepare ( http://www.sciencemag.org/cgi/content/short/308/5728/1565 ) suggest that candidates perceived as less competent in the study probably looked more "babyfaced" -- a facial quality often associated with being submissive, naïve and weak.
Black-capped chickadees are common North American songbirds that defend themselves by ganging up and mobbing predators to drive them away. To these birds, small, agile predators like pygmy owls pose a more lethal threat than larger, more fearsome looking predators like the great horned owl. Now, a fascinating study by Templeton et al. ( http://www.sciencemag.org/cgi/content/short/308/5730/1934 ) in the 24 Jun 2005 Science reports that chickadees have a sophisticated system of alarm calls that convey information about the size of potential predators and appear to help the chickadees mount a coordinated defense that is calibrated to the predatory threat. The birds make two kinds of alarm calls: a soft, high-pitched "seet," previously found to indicate the presence of predators flying overhead; and the louder namesake "chick-a-dee," used in a variety of situations from signaling the presence of stationary predators to identifying flock mates. The researchers recorded more than 5000 chickadee calls made in response to nearby predators and discovered that the birds made more "chick-a-dee" calls and incorporated more "dee" syllables into each call when they saw a small raptor. Larger or less threatening creatures like quails elicited fewer, shorter calls. When the team played back recorded alarm calls through a hidden speaker, the chickadees mounted a more intense mobbing response when they heard a small predator alarm call. As noted in a related News story by G. Miller ( http://www.sciencemag.org/cgi/content/short/308/5730/1853a ), the researchers hypothesize that more "dees" means more danger.
Ivory-Billed Woodpecker Returns
Bird-lovers rejoice! A woodpecker believed to have gone extinct has been rediscovered in a wildlife refuge in the Big Woods region of eastern Arkansas. The ivory-billed woodpecker, the third largest in the world, once lived throughout the southeastern United States. But destruction of its forest habitat caused severe population declines in the 1800s, and by the mid-20th century, the bird seemed to have vanished. Now, a Report by Fitzpatrick et al. ( http://www.sciencemag.org/cgi/content/short/308/5727/1460 ) in the 3 Jun 2005 Science (published online 28 April 2005) details the existence of at least one male bird. Repeated visual encounters during 2004 and 2005 and analysis of a video clip from April 2004 confirm the individual as an ivory-billed woodpecker. Extensive surveys failed to locate ivorybills elsewhere in the 220,000 hectares of bottomland forest, which indicates that the population density is extremely low. As noted in an accompanying Perspective by D. S. Wilcove ( http://www.sciencemag.org/cgi/content/short/308/5727/1422 ), the discovery of the ivorybill within the borders of the Cache River National Wildlife Refuge offers a ray of hope for conservationists and underscores the importance of preserving representative examples of all types of ecosystems -- a sentiment that was echoed in a related Editorial by D. Kennedy ( http://www.sciencemag.org/cgi/content/short/308/5727/1377 ).
The conversion of biomass to biofuel could provide a route to cleaner fuels from renewable resources and ultimately help reduce our dependence on oil for energy. To that end, scientists have devised a way to convert sugars and starch to ethanol, but the overall energy efficiency of the process remains low. Alternatively, biomass can be converted to hydrogen, but this would require an expensive new infrastructure to accommodate safe storage and transport. In a Report in the 3 Jun 2005 Science, Huber et al. ( http://www.sciencemag.org/cgi/content/short/308/5727/1446 ) described a new method that avoids these problems by converting carbohydrates directly to hydrocarbons. Their process involves a series of catalytic dehydration and hydrogenation steps that lead to the formation of alkanes -- hydrocarbon molecules consisting only of single carbon-carbon bonds. Moreover, the liquid alkanes are of the appropriate molecular weight to be used as transportation fuel components, and retain 90% of the energy content of the carbohydrates and hydrogen needed to produce them. Further studies will be needed to optimize the reactions and analyze the cost of the process compared with alternative routes. As noted in accompanying Perspective by J. R. Rostrup-Nielsen ( http://www.sciencemag.org/cgi/content/short/308/5727/1421 ), however, the new work "shows how explorative work can create new options for the supply of energy."
The scientific revolution that has unfolded in the West over the last 500 years owes its beginnings to the Islamic scholars of the Arab world. As scientific pursuit flourished in the West, however, the Arab world largely shifted to a more conservative worldview that persists today and has stifled the free flow of information required for scientific progress. In this month's "Global Voices of Science" essay ( 3 Jun 2005; http://www.sciencemag.org/cgi/content/short/308/5727/1416 ), Syrian scientist Wasim Maziak argues that the same information revolution that so many Arabs perceive as threatening also presents an unprecedented opportunity to close the science and technology gap. Maziak is the director of the Syrian Center for Tobacco Studies, a pioneer collaborative research center that aims to develop a culturally sensitive tobacco program to help smokers in Syria and other Arab countries quit smoking. He believes that science and technology can not only help to feed people, improve their health, and create wealth, but they can help reduce societal tensions and foster understanding and cooperation between people and nations. An online slideshow ( http://www.sciencemag.org/sciext/globalvoices/ ) accompanied the essay.
Workers around the world carry impressively heavy loads atop their heads for long distances and sometimes through arduous terrain. Until now, the most economical head-carriers were thought to be African women, who can carry loads up to 60% of their body weight more efficiently than army recruits carrying equally heavy backpacks. In the 17 Jun 2005 Science Bastien et al. ( http://www.sciencemag.org/cgi/content/short/308/5729/1755 ) reported that Nepalese porters such as Sherpas -- a group well known for their role in Mount Everest expeditions -- can carry even more weight, more efficiently. These porters routinely carry head-supported loads exceeding their body weight for many kilometers up and down steep mountain footpaths. To determine the energetic costs of such work, the researchers measured the oxygen consumption and carbon dioxide production of randomly selected porters walking at different speeds with a variety of cargo loads. Compared to control subjects (Europeans carrying backpacks), the Nepalis used significantly less energy. Female porters, for example, can carry average loads that are 10% of their body weight heavier than the maximum loads carried by the African women, yet do so at a 25% smaller metabolic cost. How they do it is still a mystery, but walking slowly and taking frequent rests seem to be key. A ScienceNOW story by M. Inman ( http://sciencenow.sciencemag.org/cgi/content/full/2005/616/2 ) highlighted the study.
In the Late Bronze Age, glass objects were high-status commodities that were often exchanged as gifts between social elites and powerful political groups. Although glass artifacts have been found at several sites in Egypt, many researchers have assumed that they are the products of secondary glassmaking (reworking ready-made glass into objects of art) and that primary glass production from raw materials actually originated in Mesopotamia. Now, a Research Article in the 17 Jun 2005 Science by Rehren and Pusch ( http://www.sciencemag.org/cgi/content/short/308/5729/1756 ) provides strong evidence that Egypt was a center of large-scale primary glass production during the 13th century. Recent excavations at Qantir-Piramesses in the eastern Nile Delta revealed fragments of glass-coloring crucibles and cylindrical vessels filled with partially attached glasses and jars. These remnants are different from the debris that is typical of secondary glass workings and indicate a two-stage glassmaking process. In the first stage, quartz powder was probably partially heated inside vessels and then crushed and washed to remove impurities. The second stage involved melting and coloring the glass in specialized crucibles to produce ingots -- cylindrical blocks of glass suitable for shipping. As noted in an accompanying Perspective by C. M. Jackson ( http://www.sciencemag.org/cgi/content/short/308/5729/1750 ), the new findings suggest that Egypt was an important center for the manufacture of and trade in glass throughout the Middle East and the Mediterranean.
Radio antennas have long been used to increase the amount of radiated power and modify the direction of radio wave emissions. In a Report in the 10 Jun 2005 Science, Mühlschlegel et al. ( http://www.sciencemag.org/cgi/content/short/308/5728/1607 ) showed that the same antenna principle can be applied to the field of nanometer-scale optics to enhance light emission. Using split strips of gold, each 100 nm long with a width of about half the wavelength of light, the team constructed an optical version of the simplest radio antenna. With the correct geometry, the antenna can capture incident light and focus into a small gap region strongly enough to generate a supercontinuum of white light. As noted in an accompanying Perspective by J.-J. Greffet ( http://www.sciencemag.org/cgi/content/short/308/5728/1561 ) the new work could find applications in quantum information processing and single-molecule spectroscopy.
The composition of Earth's mantle and crust is thought to be close to that of chondritic meteorites, the likely building blocks of the terrestrial planets. A key to the geochemical benchmarking of Earth has been the ratio of the isotope neodymium-142 to neodymium-144 (products of the radioactive decay of samarium), which can be used to trace geological processes. Measurements taken in the 1980s showed that the ratio in both chondritic meteorites and terrestrial rocks was indeed similar. Now, a Report published online ScienceExpress on 16 Jun 2005 by Boyet and Carlson ( http://www.sciencemag.org/cgi/content/abstract/1113634 ) presents new, more precise isotopic data which show that chondritic meteorites have a different neodymium ratio that that of rocks sampled on Earth, the moon, and Mars. The researchers propose that this difference likely arose within 30 million years of Earth's formation, when a small portion of the mantle became isolated from the rest of the mantle and enriched in certain elements. The bulk mantle, left with a different composition from that of chondrites, then formed Earth's continental and oceanic crust, as well as the moon. As noted in a related News story by R. A. Kerr in the 17 June issue ( http://www.sciencemag.org/cgi/content/short/308/5729/1723 ), the new data impact models and calculations of the composition of the rocky Earth, as well as the amount of interior heat being generated by radioactive decay.
Earth, Ice, and Sea Level Rise
Global sea levels are predicted to rise as a result of global warming, but the contributions to this sea level rise are poorly understood. Although Antarctica's melting ice sheets are likely contributors, they remain a major source of uncertainty because of insufficient data from the last 100 years. Two Reports in Science this month provided new insights into influence of Antarctic ice on past and future sea level rise.
--Davis et al. ( 24 Jun 2005, published online Science Express 29 May; http://www.sciencemag.org/cgi/content/short/308/5730/1898 ) used satellite data to compile an 11-year record of surface elevation change in Antarctica. The resulting maps and analysis indicate that high amounts of snowfall have increased the thickness of the interior of the East Antarctic ice sheet from 1992 to 2003, which could slow sea level rise, but that other parts of the ice sheet have thinned. An accompanying Perspective by D. G. Vaughan ( http://www.sciencemag.org/cgi/content/short/308/5730/1877 ) cautioned that the complex patterns of change in Antarctica preclude prediction of which effect will dominate in the future.
--Bassett et al. ( published online Science Express 23 Jun 2005; http://www.sciencemag.org/cgi/content/abstract/1111575 ) looked at the influence of Earth and ice processes on sea level. Previous attempts to simulate the sea level rise due to the melting of ice sheets after the Last Glacial Maximum (about 14,000 to 9,000 years ago) have failed to explain the records of sea-level change in distant locations such as Tahiti and the Sunda Shelf. Their new study shows that by using a model that combines a stiff lower mantle and rapid melting of Antarctic ice sheets, the reconstructed record and the data agree well. These results provide another line of evidence that Antarctic ice was responsible for more of the deglacial sea level rise than previously thought.