News in Brief: Atom & Cosmos

Getting to supernova
White dwarf stars often don’t waltz together when they die. A new survey of 41 “Type Ia” supernovas, the explosions these dwarfs die in when they suck too much material off another star, found sodium gas flowing away from many of the explosions. But white dwarfs are mostly made of carbon and oxygen, so the sodium gas was probably thrown off by an ordinary or giant star. That suggests that the dwarfs weren’t eating their own kind. Knowing how Type Ia supernovas form is important because astronomers use their brightness to help measure cosmic distances. An international team of researchers reports the discovery in the Aug. 12 Science. —Alexandra Witze

Sunspots rising
Magnetic fields lurking deep beneath the sun’s surface could signal the imminent emergence of sunspots. Using the Solar and Heliospheric Observatory satellite, scientists have spotted such fields, much stronger than models had predicted, up to 65,000 kilometers below the surface. Over the course of a day or two, the magnetic disturbances rise upward and eventually trigger the formation of sunspots. Knowing sunspots are coming could help people better prepare for telecommunications and other outages caused by space weather, Stathis Ilonidis of Stanford University and colleagues write in the Aug. 19 Science. —Alexandra Witze

Found in: Atom & Cosmos

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Butterfly species a master of disguise

Tasty Heliconius numata butterflies (right) mimic the wing patterns of foul-tasting Melinaea butterflies (left) to avoid getting eaten. Genetic tricks using a supergene allow the butterflies to faithfully masquerade as other species. © Mathieu Joron

The tasty Heliconius numata butterfly evades predators by copying the wing patterns of foul-tasting Melinaea butterflies. H. numata, also known as the passion-vine butterfly, has to get the pattern exactly right or a sharp-eyed bird will spot the fake and gobble it up.

Born mimics, members of the species lock in wing patterns with flipped-around bits of DNA, Richard ffrench-Constant of the University of Exeter in England and colleagues report online August 14 in Nature.

The flipped DNA causes six or more genes — on a section of a chromosome important in setting wing patterns in butterflies and peppered moths — to be inherited as a single unit, a supergene. Different versions of the super­gene allow H. numata to adopt seven different wing patterns reminiscent of several bad-tasting species.

Other Heliconius butterflies mimic only one nonpalatable species. Researchers aren’t sure if other butterfly species use DNA flipping to determine their patterns. 

Found in: Genes & Cells and Life

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Stress spears deployed service personnel

LAS VEGAS — Soldiers fighting at the tip of the spear — the leading edge of combat — confront fighting, suffering and dying. But the success of those soldiers’ operations depends on a huge network of service and support personnel who themselves face considerable and often overlooked war stress, says military sociologist Wilbur Scott of the U.S. Air Force Academy in Colorado Springs.

After returning from one or more deployments, National Guard combat service personnel — including clerks, truck drivers, medics and supply officers — displayed slightly less emotional resilience and described having experienced more stress while overseas and after returning home than their comrades engaged in combat, Scott reported August 20 at the annual meeting of the American Sociological Association.

In particular, combat service personnel cited deployment stress triggered by exposure to danger, life-threatening situations and death.

Their responses reflect the changed nature of warfare, Scott suggested. In Iraq and Afghanistan, counterinsurgency efforts have replaced conventional warfare. “While those in combat arms typically are thought of as being at the tip of the spear, this thinking applies more accurately to conventional settings rather than those encountered in Iraq and Afghanistan,” Scott said.

Combat units not only fight and kill but establish relationships with local officials, head local building projects and encourage trust in local governments. Service personnel work in the midst of operations, where they can encounter guerilla attacks or roadside bombs.

Poor coping upon returning from National Guard deployment — whether among former service personnel or combat troops — usually involved excessive alcohol drinking, abuse of prescription drugs and carrying a gun for protection, Scott said. Those behaviors are a potentially deadly mix.

Such findings underscore the need to provide programs that ease veterans back into civilian life, commented military sociologist Bradford Booth of ICF International, a private research and consulting firm in Fairfax, Va. Booth directed a pilot study of a government-funded program for 4,000 National Guard members returning home in 2007 from a year in Iraq.

In that study, those who attended three once-a-month training sessions — which focused on mental health issues, strengthening marriages, financial counseling and other topics — displayed signs of adjusting better than vets who declined to attend training.

Although traditionally regarded as “weekend warriors,” National Guard volunteers now regularly get deployed for up to one year in Iraq and Afghanistan.

Scott and his colleagues surveyed 1,460 Army National Guard soldiers, including 969 deployed solely to war zones in Afghanistan or Iraq.

Whether combat or service personnel, soldiers returning from war zones were most likely to report having grappled with and found some meaning in their military experiences. Yet they also reported the most symptoms of post-traumatic stress disorder and the worst difficulties readjusting to civilian life.

“Experiencing personal growth from going through tough times doesn’t mean you’re doing well,” Scott said.

Found in: Humans and Science & Society

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Lager's mystery ingredient found

Galls — growths resulting from a fungal infection — grow on southern beech trees in Northern Patagonia. Scientists recently found a wild yeast that gave rise to a hybrid yeast used to brew lagers in such galls on trees growing in and near two national parks in Argentina.Diego Libkind

Lager beers got their start in Bavaria, but it was a little South American spice that really kicked things off.

Scientists have known for decades that a hybrid species of yeast, Saccharomyces pastorianus, is the microbe that ferments lagers. It’s also well known that one parent of S. pastorianus is the common baking and brewing yeast Saccharomyces cerevisiae. But the other parent of lager yeast has eluded scientists, who have scoured Europe and North America looking for it.

Turns out they were looking in the wrong hemisphere. An international team of researchers led by Chris Todd Hittinger of the University of Wisconsin–Madison and Diego Libkind of the Argentinean National Council for Scientific and Technical Research in Bariloche has tracked the missing wild parent of lager yeast to the beech forests of Patagonia. The researchers report the capture of the newly discovered yeast, dubbed Saccharomyces eubayanus, online the week of August 22 in the Proceedings of the National Academy of Sciences.

“I got chills reading [about] it, I was so excited,” says Barbara Dunn, a comparative geneticist at Stanford University who has been on the trail of the wild yeast herself. “It is incredibly surprising that it is from Patagonia.”

Libkind found S. eubayanus in galls — pale peach, balloonlike structures resulting from fungal infections — on Patagonian beech trees. The galls, full of sugar, house S. eubayanus and another wild yeast that ferment the sugars. It’s generally chilly in Patagonia, just the way lager yeast like it. Lagers are brewed at 4° to 9° Celsius (39° to 48° Fahrenheit).

The S. cerevisiae yeast used for making ales, wines and other alcoholic beverages don’t like the cold, preferring temperatures of about 15° to 25° C (59° to 77° F). So when Germans started brewing beers in the winter to avoid summertime contaminants such as molds, bacteria and other things that skunk beer, the new brewing conditions would have favored the creation of a hybrid lager yeast based on S. cerevisiae and a cold-loving relative, says Antonis Rokas, an evolutionary biologist at Vanderbilt University.

The surprise is where that partner came from. Bavarian brewers started making cold-brewed beers in the 15th century, before Columbus crossed the Atlantic (although the lagers didn’t have a big breakout in popularity until much later). S. eubayanus probably hopped a ship for Europe sometime early in the 16th century. The researchers aren’t sure exactly how S. eubayanus got to Bavaria; perhaps by hitching a ride on pieces of beech wood or barrels made of beech, or on fruit or even in the belly of a fruit fly. However it got to Europe, when S. eubayanus arrived it found a ready-made niche and a partner to merge with, Rokas speculates.

It’s also possible that S. eubayanus lives or lived in some forgotten pocket of the Old World, Hittinger says. “Obviously we haven’t searched every habitat on the entire globe.”

Knowing the identity of the wild parent may help scientists learn how the lager hybrids formed and how domestication genetically changed the yeast, Rokas says. Brewers may also be able to create new hybrid strains that can be tailored for modern brewing practices.

Found in: Genes & Cells

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Spoilers freshen up stories

People who read the last page of a mystery novel first may be on to something. Giving away plot surprises generally makes readers like stories better, say psychology graduate student Jonathan Leavitt and psychologist Nicholas Christenfeld, both of the University of California, San Diego.

Volunteers especially enjoyed classic short stories, including mysteries and tales with ironic twists, after seeing spoiler paragraphs that revealed how the yarns ended, Leavitt and Christenfeld report in a paper published online August 12 in Psychological Science.

“Spoilers may enhance story enjoyment by making texts easier to read and understand, leading to deeper comprehension, or they may reduce readers’ anxiety about what’s to come, allowing them to focus on a story’s aesthetic details,” Leavitt says. These responses could explain why a favorite book can be read many times with undiminished pleasure, he suggests.

It’s also possible that spoilers amplify stories’ appeal by increasing tension, Leavitt adds. Giving away the ending of, say, Oedipus Rex may elicit pleasurable tension as a reader contemplates the title character marching unknowingly to his doom.

“The impact of suspense on enjoyment seems likely to be more complicated than the simple take-home point of this new article,” remarks psychologist Leigh Ann Vaughn of Ithaca College in New York. Spoilers may apply a pleasant oomph to well-told tales but could easily intensify readers’ distaste for unappealing or boring stories, Vaughn suggests.

Leavitt and Christenfeld recruited 819 college students to read short ironic-twist tales, mysteries and literary stories. For each story, the researchers created a spoiler paragraph that revealed the outcome in a seemingly inadvertent way. Data from students who had previously read these stories were excluded.

Each volunteer read one story after reading a spoiler beforehand, a second story with the spoiler incorporated as the opening paragraph and a third narrative with no spoiler.

Some spoilers in the new study revealed ironic plot twists, such as mentioning that a condemned man’s apparent escape from hanging is just a momentary fantasy, or they demystified crimes, such as divulging that an apparent target of attempted murder turned out to be the perpetrator.

Spoilers also spiced up subtler stories. One paragraph overtly disclosed that a teenage boy and girl watching a couple struggle with a baby were glimpsing their own future, while the couple relived their own past upon seeing the teens.

Overall, participants reported liking all stories best after first reading spoilers. Spoilers incorporated into the beginning of the text had no effect on story enjoyment, yielding no more pleasure than unspoiled stories.

That result may be due to peoples’ general belief that spoilers ruin stories. So giving away outcomes in a way that seems unintended — as in artfully worded prefatory paragraphs or book reviews — may be necessary to enrich reader satisfaction, Leavitt proposes.

Birthday presents wrapped in cellophane, like stories preceded by spoilers, would give recipients an unexpected thrill, he predicts. “In both cases, the outcome is known, yet there is still pleasure in unraveling the clues, or the plastic wrap, as the case may be,” Leavitt says.

Found in: Humans and Psychology

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News in Brief: Earth & Environment

Antarctic ice flows, atmospheric response to nuclear fallout and more in this week's news Web edition : Saturday, August 20th, 2011 Moving Antarctic ice forms a tributary system across the continent in this map based on satellite radar.Science/AAAS

Icy flows

A new map of Antarctica assembled from satellite radar data reveals how ice shifted around on the frozen continent between 2007 and 2009. Ice flowing through narrow channels forms a river-like tributary system that accounts for much of the movement, a team led by Eric Rignot of the University of California, Irvine reports online August 18 in Science.  Researchers want to better understand how great ice sheets like Antarctica’s respond as global temperatures rise. —Alexandra Witze

Arctic may get breather in sea-ice losses

Roughly half of the recent loss of summertime Arctic sea ice appears to be due to greenhouse gas emissions as a result of human activity, the rest from natural climate variability, report scientists at the National Center for Atmospheric Research in Boulder, Colo. Their new analyses also indicate that even as global warming continues, summer Arctic sea ice losses could pause. “We could see a 10-year period of stable ice or even an increase,” says lead author Jennifer Kay. Her team’s analyses appeared online August 11 in Geophysical Research Letters. —Janet Raloff

Japanese fallout left electric signature

Radioactive fallout from the tsunami-crippled Fukushima reactors in Japan caused a rapid and dramatic response in the atmosphere’s electric field. The effect, brought about by a change in the atmosphere’s charge, showed up 150 kilometers southwest of the nuclear facility. Similar changes have occurred elsewhere after nuclear weapons tests and the Chernobyl accident, usually as rain washed fallout from the air. The Japanese radiation signature instead marked the arrival of fallout carried by dry low-altitude winds, scientists from Japan and Sweden reported online August 12 in Geophysical Research Letters. They conclude that early-warning electrical sensors be installed around all reactors to detect fallout. —Janet Raloff

Found in: Earth and Environment

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Magnitude 5.8 earthquake hits Virginia

A map released by the USGS reveals the epicenter of Tuesday’s earthquake in Virginia (red star), as well as areas of "very strong" shaking with the potential for "moderate" damage (orange). Less intense shaking fades to turquoise.USGSThe seismically sleepy mid-Atlantic states were struck by a magnitude 5.8 earthquake on August 23. At 1:51 p.m. EDT on Tuesday an earthquake struck Virginia, 135 kilometers southwest of Washington, D.C. It’s among the largest temblors to strike the state in recorded history.

The quake’s epicenter was located in central Virginia about 61 kilometers northwest of Richmond, at a preliminary estimated depth of 6 kilometers. Reports of the quake were posted on the U.S. Geological Survey’s Did You Feel It? website from as far away as Ohio and New York. That’s not unusual for earthquakes on the East Coast, which are commonly felt over a wide area.

“An event of the same size is felt over a much larger area in the East, compared to the West,” says Charles Ammon, an earthquake seismologist at Pennsylvania State University in University Park.

Vibrations from an 1897 temblor centered on Virginia’s Giles County, magnitude 5.9, reached Georgia and Pennsylvania and as far westward as Kentucky and Indiana. Chimneys crumbled and visible fissures appeared during this event.

On Tuesday, buildings rattled and lights flickered as people took to the streets in the nation’s capital. Both the U.S. Capitol Building and the Pentagon were evacuated, the Associated Press reported — as was the building that houses the USGS Earthquake Hazards Program in Reston, Va. While it’s unclear if the city’s buildings suffered much structural damage from the quake, three pinnacles did snap off the central tower of the Washington National Cathedral, says Richard Weinberg, media spokesperson. Stone masons and engineers are assessing the full extent of the damage.

Earthquakes in the mid-Atlantic tend to be small — like last year’s magnitude 3.6 temblor beneath Germantown, Md. The East Coast lacks the active fault systems created by colliding continental plates characteristic of California and the West Coast. The crust that underlies the mid-Atlantic region tends to be older, cooler and more stable. The recent quake likely started on a previously unknown fault that has been dormant for a long time in the middle of the Central Virginia Seismic Zone.

The East Coast isn’t entirely immune to big ones, though. In 1886 an earthquake registering between magnitude 6.6 and 7.3 hit Charleston, S.C., damaging an estimated 2,000 buildings and killing dozens of people.

A small magnitude 2.8 aftershock gently rocked Virginia again at 2:46 p.m. Rumors, spread in some initial news reports about the event, that this latest earthquake is a foreshock coming before a larger event are just speculation.

“There’s no scientific method that could identify a foreshock,” says Ammon.

Found in: Earth and Earth Science

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