大家好，胖胖翔来啦！第三和第四篇来自一篇文章，enjoy~
Part I: Speed
Article 1 Shhh, the Plants Are Talking
The word in the garden is that basil is good to have around. Plants are known to communicate with each other via shade, aromatic chemicals, and physical touch, promoting processes such as growth and defense against disease, as well as attraction of bees and other pollinators. Now, online today inBMC Ecology, researchers report a new type of mechanism that some plants use to communicate. The team planted common chili pepper seeds (Capsicum annuum, pictured) near a basil plant, with barriers that prevented the basil from deploying its usual growth-promoting tricks. Despite the separation, chili seeds germinated faster when basil was a neighbor, suggesting that a message was getting through. Because light, touch, and chemical "smell" were ruled out, the team proposes that the finding points to a new type of communication between plants, possibly involving nanoscale sound waves, traveling through the dirt to bring encouraging "words" to the growing seeds. Understanding this novel communication could help growers boost crop yields and increase global food supplies. How neighborly.
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[Time 2] Article 2 Getting the Straight Poop From Dolphins
It's not that easy to figure out what dolphins eat. They refuse to fill out food diaries and you can't watch them without bothering them—humans are pretty conspicuous out there with our scuba gear and boats. What scientists know about the dolphin diet comes mostly from the stomachs of animals that turn up dead on the beach or in fishing gear. But nobody knows if those animals are good representatives for their species. For a new study, researchers focused on the well-studied bottlenose dolphins that live in Florida's Sarasota Bay. While the animals were getting routine health assessments in the summers of 2005 and 2006, researchers collected 15 samples of poop—most straight from the anus, some out of the water. They also drained gastric juice from the stomachs of nine dolphins, which didn't hurt the animals. Then they did DNA analysis to figure out which species the cetaceans had been snacking on. The scientists compared their results to those obtained from the stomach contents of 32 stranded dolphins over 22 years. The bottom line: Actually, stomach contents are a pretty good indicator of dolphin diet. The live and dead dolphins were eating many of the same species, mostly ray-finned fish, in similar amounts, the team reports online today in Biology Letters. Among other things, the study confirms that the dolphins' most-eaten food is a fish that lives in seagrass, a sensitive ecosystem. It also means that the data biologists have been using are fine—at least for a population like this that hangs out close to shore. Things could be different for farther-ranging animals. [字数：266]
[Time 3]
Article 3 US bill would keep helium store afloat Russia and Qatar prepare to dominate market as gas price inflation puts researchers under pressure.
US lawmakers have taken a significant step towards averting a global crisis in helium supply, thanks to a bill passed by the House of Representatives on 26 April. If it passes the Senate and becomes law, the bill would delay the imminent closure of the world’s only strategic helium reserve. It would also increase the price of the gas from the reserve, so helium-dependent researchers and industry could still face ballooning costs. However, the prospect of higher prices is encouraging the development of new helium sources in Qatar and Russia, which may ultimately lead to a more stable helium market. With a boiling point of 4 kelvin — lower than that of any other element — liquid helium has many uses, including cooling the super conducting magnets in medical imaging scanners. The semiconductor industry also relies on the inert gas to shield delicate crystals from contaminants during manufacturing. Demand is on the rise. More than 100 million cubic metres of helium is extracted from natural gas worldwide every year, yet meeting global needs requires a further 60 million cubic metres a year from the US Federal Helium Reserve, a vast geological reservoir near Amarillo, Texas, that stores helium from past gas extraction. In the mid-1990s, the reserve boasted 1 billion cubic metres of the gas — and a debt of US$1.3 billion accrued after a large buy-up of helium in the 1960s. Over time, the simple formula used to calculate the price of helium sold from the reserve has failed to keep pace with commercial prices. In 1996, appalled that the government was undercutting a booming commercial gas market, lawmakers passed the Helium Privatization Act. Its goal was to sell the helium reserve to pay off the debt. Once the debt was gone, no more helium would be sold. “They would literally turn off the tap,” says Richard Clarke, a process and resources consultant based in Oxford, UK. The shutdown was expected by October this year. And because the reserve’s cut-rate prices had dissuaded companies from developing sources elsewhere, a supply shortage was possible. “The Privatization Act has come back to bite them,” says Clarke. Alarmed, researchers and high-tech industries lobbied Congress to keep the helium flowing. Congress responded: the Responsible Helium Administration and Stewardship Act passed by the House maps out a more orderly shutdown. A similar bill has been introduced to the Senate; if it passes this summer, as is expected, and the law takes effect, the stockpile would be sold to the highest bidders in semi-annual auctions, until just 85 million cubic metres are left. Experts say that point might be reached in 2020, and prices could rise by 50% in that time. [字数：459]
[Time 4]
The remaining stock would be available only to government users such as NASA. “The United States will have ceased to be the major player in helium production,” says William Nuttall, an energy expert at the Open University in Milton Keynes, UK. Users will increasingly depend on helium from gas fields in Qatar, Algeria and Russia. The Russian energy giant Gazprom aims to capture the lion’s share of the market. Last year, the global business consultancy Ernst & Young, based in London, estimated that gas fields in eastern Siberia could produce 250 million cubic metres of crude helium per year by 2030, satisfying at least three-quarters of projected demand. One of the most promising resources is the Chayandinskoye natural-gas field, which contains a relatively rich bounty of about 0.5% helium. In the past six months, Gazprom has signed cooperation agreements with many of the leading companies that purify and supply helium, including Air Liquide, Linde and Matheson. Helium could start to flow from Chayandinskoye by 2018. In Qatar, extra helium-production capacity is scheduled to come online this year. The Ras Laffan Helium 2 plant could enable the country to meet up to 25% of global helium demand — although much of its output will head east to serve the growing Asian market, says Clarke. And private efforts in the United States seem to be ramping up. In March, Flatirons Resources of Denver, Colorado, received approval from the US Bureau of Land Management to develop a small well designed to tap helium from a Utah natural-gas field — the first US well devoted solely to helium. Helium may not run short, but the price increases will hurt labs, says Jodi Lieberman, senior government-relations specialist at the American Physical Society, headquartered in College Park, Maryland. Some low-temperature physicists already spend up to 70% of their grants on the gas, she adds. In a 2010 report, Selling the Nation’s Helium Reserve, the US National Academy of Sciences (NAS) recommended that funding agencies help researchers to buy cooling systems that recycle helium, or reduce its consumption. So far, cash-strapped funders have not had the resources to make the expensive equipment widely available, says James Lancaster, NAS study director for the report. But as prices float skyward, helium-sparing equipment may start to look like a necessity. [字数：378]
[Time 5] Article 4
Moon rocks offer new view of lunar dynamo Process that generated magnetism lasted 160 million years longer than previously thought.
The Moon clung to its magnetic field until at least 3.56 billion years ago, a study suggests — about 160 million years longer than scientists had thought. That small change may be enough to rule out some ideas about how the Moon generated and held onto its ancient magnetism, through a process known as a dynamo. “It seems like the lunar dynamo lasted very late in the Moon’s history,” says Benjamin Weiss, a palaeomagnetics expert at the Massachusetts Institute of Technology (MIT) in Cambridge. “That’s a very surprising result.” Weiss and his colleagues, led by MIT planetary scientist Clément Suavet, report the findings today in the Proceedings of the National Academy of Sciences. Although the Moon has no global magnetic field today, rocks collected during the Apollo missions show that it once did. Molten rock churning in a planet’s interior can generate a dynamo, and researchers have suggested several possible triggers for this stirring. An extraterrestrial impact — from chunks of rock left over from the Solar System’s formation, for example — could have smashed the Moon hard enough to jolt liquid in its interior. Or heat differences caused by radioactive decay could have prompted liquid to shift in great convective movements, like a pot of water boiling on the stove. To know which option is correct, scientists must first determine how long the dynamo lasted and how strong it was at various points in history. Suavet and his team tackled these questions by re-analysing two 3.56-billion-year-old rocks collected by the Apollo 11astronauts in 1969. Using several techniques, the scientists found that the rocks had magnetic fields of 13–70 microtesla. The higher end of that range is comparable to Earth’s magnetic field today. The fact that the Moon still had a magnetic field 3.56 billion years ago should rule out impact as the origin of the Moon’s dynamo at that time, says Suavet. The dates do not line up: lunar impacts large enough to stir up a core dynamo dropped off around 3.72 billion years ago, and any dynamo created this way would have also soon faded. A better option, Weiss says, may be a theory proposed in Nature in 2011 by Christina Dwyer, a planetary scientist at the University of California, Santa Cruz, and her colleagues2. It holds that Earth’s gravitational tug may have caused the Moon’s solid mantle and liquid core to separate and move in such a way as to keep stirring the fluid. “I’ve been hoping to see measurements like this,” Dwyer says of the latest study. “It really does help differentiate among different models for how the dynamo occurred.” Those who support an impact-driven dynamo aren’t giving up so easily. Michael Le Bars, a fluid dynamicist at the Non-Equilibrium Phenomena Research Institute in Marseille, France, published an impact explanation for the lunar dynamo in the same issue of Nature in which Dwyer's paper appeared. He says that extraterrestrial impacts could have kicked off a dynamo earlier in the Moon’s history. “We are convinced, from fluid-mechanics arguments, that impacts indeed produced a magnetic field at some point,” Le Bars says. Indeed, the Moon could have had different dynamos generated through different mechanisms at different times, Suavet and Weiss say. They are now looking at other, even younger, Moon rocks to try to pin down whether the dynamo lasted beyond 3.56 billion years ago. [字数：567] Part II: Obstacle Article 5
Heavy Metals, Insects and Other Weird Things Found in Lipstick Through Time
Lipstick has seen a fair share of funky ingredients in its long history of more than 6,000 years, from seaweed and beetles to modern synthetic chemicals and deer fat. In recent years, traces of lead have been found in numerous brands of the popular handbag staple, prompting some manufacturers to go the organic route. This week, more dangerous substances joined the roster.
Researchers at Berkeley’s School of Public Health at the University of California tested 32 different types of lipstick and lip gloss commonly found in the brightly lit aisles of grocery and convenience stores. They detected traces of cadmium, chromium, aluminum, manganese and other metals, which are usually found in industrial workplaces, including make-up factories. The report, published in the journal Environmental Health Perspectives, indicated that some of these metals reached potentially health-hazardous levels. Lipstick is usually ingested a little by little as wearers lick or bite they lips throughout the day. On average, the study found, lipstick-clad women consume 24 milligrams of the stuff a day. Those who reapply several times a day take in 87 milligrams. The researchers estimated risk by comparing consumers’ daily intake of these metals through lip makeup with health guidelines. They report that an average use of some lipsticks and lip glosses results in “excessive exposure” to chromium, and frequent use can lead to overexposure to aluminum, cadmium and manganese. Minor exposure to cadmium, which is used in batteries, can result in flu-like symptoms such as fever, chills and achy muscles. In the worst cases, the metal is linked to cancer, attacking the cardiovascular, respiratory and other systems in the body. Chromium is a carcinogen linked to stomach ulcers and lung cancer, and aluminum can be toxic to the lungs. Long-term exposure to manganese in high doses is associated with problems in the nervous system. There are no safe levels of chromium, and federal labor regulations require industrial workers to limit exposure to the metal in the workplace. We naturally inhale tiny levels of aluminum present in the air, and many FDA-approved antacids contain the metal in safe levels. Despite the presence of these metals in lipstick, there’s no need to start abandoning lipstick altogether—rather, the authors call for more oversight when it comes to cosmetics, for which there are no industry standards regulating their metal content if produced in the United States. After all, cadmium and other metals aren’t an intended ingredient in lipstick—they’re considered a contaminant. They seep into lipstick when the machinery or dyes used to create the product contain the metals themselves. This means trace amounts are not listed on the tiny stickers on lipstick tubes, so there’s no way to know which brands might be contaminated. Concern about metals in cosmetics came to the forefront of American media in 2007, when an analysis of 33 popular brands of lipstick by the Campaign for Safe Cosmetics showed that 61 percent of them contained lead. The report eventually led the Food and Drug Administration (FDA), which doesn’t regulate cosmetics, to look into the issue, and what it found wasn’t any better: it found lead in all of the samples tested, with levels four times higher than the earlier study, ranging from 0.09 parts per million to 3.06 parts per million. According to the Centers for Disease Control and Prevention, there is no safe level of lead for humans. So we’ve got cadmium, chromium, aluminum, manganese and lead in our lipstick. What else? Today, most lipstick is made with beeswax, which creates a base for pigments, and castor oil, which gives it a shiny, waxy quality. Beeswax has been the base for lipstick for at least 400 years–England’s Queen Elizabeth I popularized a deep lip rouge derived from beeswax and plants. Lipstick as we know it appeared in 1884 in Paris, wrapped in silk paper and made from beeswax, castor oil and deer tallow, the solid rendered fat of the animal. At the time, lipstick was often colored using carmine dye. The dye combined aluminum and carminic acid, a chemical produced by cochineals–tiny cacti-dwelling insects–to ward off other insect predators. That early lipstick wasn’t the first attempt at using insects or to stain women’s mouths. Cleopatra’s recipe for homemade lipstick called for red pigments drawn out from mashed-up beetles and ants. But really, any natural substance with color was fair game for cosmetics, regardless of its health effects: Historians believe women first starting coloring their lips in ancient Mesopotamia, dotting them with dust from crushed semi-precious jewels—these lovely ancients were eating tiny bits of rocks whenever they licked their lips. Ancient Egyptians used lip color too, mixing seaweed, iodine and bromine mannite, a highly toxic plant-derived chemical that sickened its users. From mannite to heavy metals, humanity’s quest for painted beauty doesn’t seem to have progressed far from toxic roots. The sacrifices we make for fashion!
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发表于 2013-5-8 09:02:20
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