Nitrous oxide, also known as laughing gas, might sound like a humorous substance. But here’s a sobering fact: The chemical now poses the largest man-made threat to the ozone layer, according to a study published in Science. Environmental policies, which have focused on controlling emissions of compounds such as CFCs, have largely ignored nitrous oxide. CFC levels have been falling since the 1989 adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer… Meanwhile, nitrous oxide levels have been climbing as a result of increased emissions from agricultural fertilizers, biomass burning and animal waste [Nature News].
Researchers used a model to compare the potential of various gases, including laughing gas, to deplete the ozone layer, compared to a compound called CClF3, a substance with one of the greatest potentials for destroying the ozone. They found that although the threat that nitrous oxide poses to ozone is small compared to CClF3, the large-scale emissions of laughing gas mean it is the most significant of the ozone-depleting substances emitted by human-related activities today…. “This is the first time someone has dealt with nitrous oxide in isolation like this,” says atmospheric chemist Susan Solomon. “It’s one of those things that has simply been overlooked” [Nature News].
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Amidst concerns over the safety of DEET, scientists are on the lookout for a new mosquito repellent. Now they may have found a way to keep biting insects at bay–by blocking their olfactory sense, according to a paper published in Nature.
Mosquitoes sense the presence of humans and animals by detecting the carbon dioxide we exhale with each breath. Researchers have found two compounds, 2,3-butanedione and 1-hexanol, that could keep the biters at bay by blocking the insects’ ability to detect this gas. Using these compounds could be advantageous because the amount of chemical required is relatively small…. Further, the chemicals themselves are not complicated to manufacture and are available through conventional sources. “From both perspectives, this adds up to a viable tool in tackling the problems like that of malaria in Africa” [Scientific American], says study coauthor Anandasankar Ray. Considering the number of diseases spread by insects such as mosquitoes–for example, 250 million people contract malaria each year–there’s a lot more at stake here than a few itchy bug bites.
Medical imaging tests such as CT scans are valuable diagnostic tools, but their increasing use in doctors’ offices and hospitals is providing a sizable dose of radiation for about 4 million Americans under the age of 65. About 400,000 of those Americans receive very high doses, more than the maximum annual exposure allowed for nuclear power plant employees or anyone else who works with radioactive material [The New York Times], according to a study published in The New England Journal of Medicine.
Researchers based their estimates on a study of almost 1 million people between the ages of 18 and 64 who they followed for almost three years, and found that nearly 70 percent of test subjects were subjected to at least one procedure that would have exposed them to radiation. Although the study didn’t examine whether this radiation could cause an increase in cancer rates, some experts believe it would probably result in tens of thousands of additional cancers…. Each individual patient is at relatively minor additional risk from the tests, [researcher and cardiologist Rita] Redberg said, but because they are given to so many people, the cumulative risk is significant [The New York Times].
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The most practical and immediate steps we can take to slow global warming may be lining roadways with towering “artificial trees” and covering buildings with algae bioreactors, argues a new report from Britain’s Institution of Mechanical Engineers. The group believes that geoengineering (a broad term for climate-altering technologies) may be necessary to reduce carbon dioxide levels immediately, while governments continue to bicker about how to transition to a low-carbon future. “Geo-engineering is no silver bullet, it just buys us time,” said Tim Fox of the IME, who led the study [The Guardian].
Fox says the study (pdf) looked for techniques that could be rolled out with existing technology. The IME’s first suggestion is to construct hundreds of thousands of “artificial trees”, essentially building- or goalpost-sized structures through which the wind blows. As air passes through them, the “trees” extract CO2 from it for later sequestration [The Register]. The fake trees are intended to be much more efficient at absorbing CO2 than real, biological trees, with current designs estimated to remove one ton of CO2 from the air daily. But even if the devices could be made ten times more efficient, the study found that 100,000 fake trees would be required to absorb the CO2 emissions from all the cars and trucks in the United Kingdom.
In a star system 330 light years away from Earth, astronomers have spotted a giant planet that booms around its parent star in tight, fast circles, completing an orbit (the planet’s “year”) in less than one Earth day. The exoplanet, known as Wasp-18b, is so close to its star that researchers say it appears to be spiraling inwards to its fiery doom. But the odds of seeing a planet in its death throes are so low that researchers are searching for alternate explanations, and say the planet could force scientists to rethink established ideas about planetary forces known as tidal interactions [National Geographic News].
The planet is known as a “hot Jupiter,” meaning that it’s a massive gas giant like our own solar system’s Jupiter, but it orbits in close proximity to its star. Current theories say that such a massive planet so close to its star should be pulling on the host star, creating a tidal effect similar to the moon’s pull on Earth. At that range the planet’s pull would be so strong that it would drain energy from its orbit, causing the planet to rapidly fall into the star [National Geographic News]. But if that’s the case, the planet would meet its death in less than a million years. Since the star system is thought to be about 1 billion years old, the odds of catching the planet in its last stages are one in a thousand.
Male Brazilian free-tailed bats sing intricate songs to attract females and deter other males using a set syllabic order and syntax, according to a study published in the journal PLoS One. The bats can even add their own creative touches to the croonings.
By examining 400 songs produced by 33 free-tailed bats, researchers found that all the bats produce songs with a common hierarchical structure. “All are constructed from the same four types of syllables and all syllables are combined in the same way to form three types of phrases,” says [lead author Kirsten] Bohn. These phrases can be either chirps, trills or buzzes [BBC News], and the complexity of the songs rival those only of birds and whales, leaving those produced by mice in the dust. The bats may vary their songs to appeal more to females or to convey different sentiments. “Within the broad rules, the bats are quite versatile” [BBC News], Bohn says.
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Video: Kirsten Bohn, et al. The slowed-down video shows a male bat singing while performing a wing-flapping display for roosting females.
These cute little macaque monkeys may have gotten their fluffy brown fur from their father, their big eyes from their mother, and their good health from… their other mother.
The scientific advance heralded in a new paper in Nature is essentially procedural: Researchers have figured out how to make an embryo that does not carry the mitochondrial DNA of its mother but that of another female instead, which could prevent diseases that are caused by inherited defects in this genetic material. But the study’s immediate impact comes from the ethical questions it raises. “With this you have potentially three genetic parents,” said [bioethics expert] David Magnus…. “This will create the potential for legal and social conflicts.” [Washington Post].
While more than 99 percent of an embryo’s DNA comes from the union of a sperm cell with the nucleus inside a female egg, the other 1 percent is found in other structures outside the egg’s nucleus–the mitochondria, the cellular power plants that produce chemical energy. This mitochondrial DNA is inherited only from the mother, but in the new study on rhesus macaques researchers monkeyed with that biological truism.
Gravity appears to be crucial to the development of mouse embryos, implying that mammalian reproduction in zero gravity may be trickier than scientists thought. Researchers have bred animals from sea urchins to frogs in space. When they tried to artificially fertilize mouse eggs in a machine that simulates a gravity-free environment, fertilization took place normally, suggesting that microgravity hadn’t harmed the sperm. But as the embryos continued to develop inside the clinostat, many developed problems. Their cells had trouble dividing and maturing [Wired].
Scientists speculate the reason that the mouse embryos developed less successfully than previous animals is because mammalian embryonic development is more sensitive and complicated than that of other types of animals. “Sustaining life beyond Earth either on space stations or on other planets will require a clear understanding of how the space environment affects key phases of mammalian reproduction” [Wired], the researchers wrote in their paper, published in the journal PLoS ONE.
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A prehistoric armadillo-like animal swung its tail like a baseball bat, taking advantage of the “sweet spot” the same way tennis and baseball players do today, according to a study published in the journal Proceedings of the Royal Society B.
The tail sported spikes at a specific location that allowed the mammals, known as glyptodonts, to deliver a strong blow while minimizing the risk of harming the tail, the researchers found; spiny-tailed dinosaurs may have used the same mechanism. Known as the “sweet spot” today in sports like baseball, this so-called “center of percussion” helps athletes avoid wrist injuries. “The center of percussion is a point where you can deliver a very powerful blow with a baseball bat, a tennis racket, a sword, an axe or any hand-held implement, but the forces against your hands are almost zero” [Discovery News], said lead author Rudemar Ernesto Blanco. The glyptodont, which went extinct about 8,000 years ago after its emergence about 2.5 million years ago, would have swung its tail about 15 meters per second–about as fast as a modern-day tennis player swinging his or her racket.
An unusual vehicle known as “the fastest kettle in the world” has busted the speed record for steam-powered cars, a record set at the beginning of the automobile age. The sleek car, named Inspiration, achieved an average speed of 139.8 miles per hour over the course of the two required runs at Edwards Air Force Base in California.
The Inspiration may sound like a crawling turtle compared to the jet-powered car that holds the world’s land speed record: Thrust SSC roared up to a speed of 763 miles per hour in 1997. But the Inspiration, a British-built car, can claim other bragging rights: The car’s boilers can produce steam at a rate fast enough to make 23 cups of tea a second–an enjoyably British fact [The Guardian].