More than one way to explode a star

There are two ways to light a cosmic candle. One technique calls for two white dwarf stars; another positions a white dwarf near a larger stellar companion. Both combinations produce type 1a supernovas (pictured here), massive stellar explosions that act as “standard candles” for gauging astronomical distances. Type 1a supernovas are triggered when white dwarfs gain weight, igniting a runaway thermonuclear reaction that destroys the dwarf, producing a fireball of predictable brightness. For a long time, astronomers disagreed over what sorts of ingredients were needed to make the white dwarf go boom.  Now, an international team of astronomers studying 23 recent type 1a fireballs reports that there are two recipes: the same ones astronomers have been arguing over for years. In both, the doomed dwarf leeches material from a companion — from either a second dwarf, producing a supernova with no surrounding gas, or from a larger star, generating a more powerful explosion and a gas cloud, the team reports in an upcoming issue of the Astrophysical Journal. In January, another team published evidence that a white dwarf–white dwarf merger produced a type 1a supernova. Understanding precisely how these type 1a explosions are generated will help refine cosmic distance measurements, helpful information for gauging the accelerating expansion of the universe.

The Risk of Listening to Amplified Music

Listening to amplified music for less than 1.5 hours produces measurable changes in hearing ability that may place listeners at risk of noise-induced hearing loss, new research shows. While further research is needed to firmly establish this risk, the investigation is significant because it provides the first acoustical data for a new method to assess the potential harm from a widespread cultural behavior: "leisure listening" to amplified music, whether in live environments or through headphones.

A team of Danish acoustics researchers present the results of their preliminary study at the Acoustics 2012 meeting in Hong Kong, May 13-18, a joint meeting of the Acoustical Society of America (ASA), Acoustical Society of China, Western Pacific Acoustics Conference, and the Hong Kong Institute of Acoustics. Their goal is to help develop recommendations for how sound engineers, musicians, event organizers, and the general public should safely enjoy amplified music so they are protected from hearing loss -- just as workers are now protected by occupational health standards.
Explains Rodrigo Ordonez, Ph.D., lead scientist of the Danish team from Aalborg University's Department of Electronic Systems: "Modern low-distortion, high-power loudspeaker systems and headphones make it easy for people to be exposed to potentially harmful sound levels at discotheques, concerts, or while using portable music players."
He adds that in the realm of industrial noise and work-related sound exposures, decades of experience and personal tragedy -- many workers lost hearing from factory conditions -- has produced the hearing-damage risk criteria currently used. Based on well-documented acoustical parameters, these criteria outline measurement procedures and expected impact on hearing.
"Yet when it comes to musical sound exposure -- and in particular, amplified music -- it is not known if the same measures used for industrial noise will accurately describe the effects on hearing and the risk these behaviors pose," Dr. Ordonez says.
To investigate the potential health risk from amplified music, the team measured sounds known as "otoacoustic emissions" as an index of auditory function. These are sounds generated within the inner ear in response to sound stimuli, and they can be measured in the ear canals of people who have healthy hearing. Research shows that otoacoustic emissions disappear when the inner ear is damaged. In this study, the researchers measured otoacoustic emissions to gauge changes in hearing ability before and after exposure to amplified music, testing this method in a live concert environment. Comparing how these two sets of measures change after a sound exposure with the acoustical parameters of the amplified music can lead to a better understanding of how our hearing is affected.
Results revealed two main findings: One is that it is possible to measure changes in hearing after exposures of relatively short duration, less than 1.5 hours. The second is that there are noticeable individual differences in sound exposure levels, as well as in the changes on otoacoustic emissions produced by similar exposure conditions.
Next steps in the team's work include refining their measurement methods and describing the biophysical effects and mechanics that music sound levels have on individuals. Ultimately they hope to provide data and a scientific rationale on which to establish damage risk criteria for music sound exposure.

NASA's Spitzer Sees the Light of Alien 'Super-Earth'

NASA's Spitzer Space Telescope has detected light emanating from a "super-Earth" planet beyond our solar system for the first time. While the planet is not habitable, the detection is a historic step toward the eventual search for signs of life on other planets.

"Spitzer has amazed us yet again," said Bill Danchi, Spitzer program scientist at NASA Headquarters in Washington. "The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA's upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets."
The planet, called 55 Cancri e, falls into a class of planets termed super Earths, which are more massive than our home world but lighter than giant planets like Neptune. The planet is about twice as big and eight times as massive as Earth. It orbits a bright star, called 55 Cancri, in a mere 18 hours.
Previously, Spitzer and other telescopes were able to study the planet by analyzing how the light from 55 Cancri changed as the planet passed in front of the star. In the new study, Spitzer measured how much infrared light comes from the planet itself. The results reveal the planet is likely dark, and its sun-facing side is more than 2,000 Kelvin (3,140 degrees Fahrenheit), hot enough to melt metal.
The new information is consistent with a prior theory that 55 Cancri e is a water world: a rocky core surrounded by a layer of water in a "supercritical" state where it is both liquid and gas, and topped by a blanket of steam.
"It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away," said Michaël Gillon of Université de Liège in Belgium, principal investigator of the research, which appears in the Astrophysical Journal. The lead author is Brice-Olivier Demory of the Massachusetts Institute of Technology in Cambridge.
The 55 Cancri system is relatively close to Earth, at 41 light-years away. It has five planets, with 55 Cancri e the closest to the star and tidally locked, so one side always faces the star. Spitzer discovered the sun-facing side is extremely hot, indicating the planet probably does not have a substantial atmosphere to carry the sun's heat to the unlit side.
NASA's James Webb Space Telescope, scheduled to launch in 2018, likely will be able to learn even more about the planet's composition. The telescope might be able to use a similar infrared method to Spitzer to search other potentially habitable planets for signs of molecules possibly related to life.
"When we conceived of Spitzer more than 40 years ago, exoplanets hadn't even been discovered," said Michael Werner, Spitzer project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Because Spitzer was built very well, it's been able to adapt to this new field and make historic advances such as this."
In 2005, Spitzer became the first telescope to detect light from a planet beyond our solar system. To the surprise of many, the observatory saw the infrared light of a "hot Jupiter," a gaseous planet much larger than the solid 55 Cancri e. Since then, other telescopes, including NASA's Hubble and Kepler space telescopes, have performed similar feats with gas giants using the same method.
In this method, a telescope gazes at a star as a planet circles behind it. When the planet disappears from view, the light from the star system dips ever so slightly, but enough that astronomers can determine how much light came from the planet itself. This information reveals the temperature of a planet, and, in some cases, its atmospheric components. Most other current planet-hunting methods obtain indirect measurements of a planet by observing its effects on the star.
During Spitzer's ongoing extended mission, steps were taken to enhance its unique ability to see exoplanets, including 55 Cancri e. Those steps, which included changing the cycling of a heater and using an instrument in a new way, led to improvements in how precisely the telescope points at targets.
JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology (Caltech) in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.
For more information about Spitzer, visit: http://www.nasa.gov/spitzer and http://spitzer.caltech.edu .

Rural life may boost allergy resistance

By Devin Powell

Children who grow up close to nature may have fewer allergies because of protective skin bacteria.
That finding is a new twist on the hygiene hypothesis, the idea that contact with bacteria early in life is crucial for the development of the human immune system. Skin microbes tied to the diversity of the natural environment seem to teach the body to calm allergic responses, researchers report online the week of May 7 in the Proceedings of the National Academy of Sciences.
“Here is yet another reason for planning green spaces in towns and cities,” says Ilkka Hanski, an ecologist at the University of Helsinki in Finland.
The decline of biodiversity in urban areas might damage the health of city dwellers by annihilating some of humankind’s tiniest allies, Hanski and his colleagues suggest. The researchers studied 118 Finnish adolescents who had lived their entire lives in a single place: a small town, a village or a house by itself in the countryside. Those teenagers who grew up near forests or farmland were less likely to have an allergic response when exposed to a cocktail of allergens.
Skin swabs revealed differences in the diversity of bacteria on the children’s skin. Life in more rural areas provided a richer variety of one kind of microbe called gammaproteobacteria.
This class of bug, found everywhere from the roots of plants to deep-sea hydrothermal vents, may be able to tinker with the immune system. In teenagers with more of the gammaproteobacteria Acinetobacter, blood cells contained more IL-10, an anti-inflammatory molecule that helps to block allergic responses.
“If what they’re looking at is a cause and not a consequence, it’s absolutely astonishing,” says Graham Rook, an immunologist at University College London. He points out that allergic responses could be changing the skin and its bacteria, instead of the other way around. Because the bacteria are probably inhaled and eaten as well, it’s also possible that they’re actually working in the gut, not on the skin.
Further studies of other human populations will be needed, says Rook, to see if the Finnish findings hold up elsewhere. Researchers don’t even know how the allegedly helpful bacteria transfer from the environment to the skin. Plants host bacteria on their leaves that might leapfrog to people. Or areas with lots of plant biodiversity might simply be healthy ecosystems in general, teeming with diverse microbes waiting to make contact.

Rapid Decline in US Earth Observation Capabilities

cienceDaily (May 2, 2012) — A new National Research Council report says that budget shortfalls, cost-estimate growth, launch failures, and changes in mission design and scope have left U.S. earth observation systems in a more precarious position than they were five years ago. The report cautions that the nation's earth observing system is beginning a rapid decline in capability, as long-running missions end and key new missions are delayed, lost, or canceled.

"The projected loss of observing capability will have profound consequences on science and society, from weather forecasting to responding to natural hazards," said Dennis Hartmann, professor of atmospheric sciences at the University of Washington, Seattle, and chair of the committee that wrote the report. "Our ability to measure and understand changes in Earth's climate and life support systems will also degrade."
The report comes five years after the Research Council published "Earth Science and Applications From Space: National Imperatives for the Next Decade and Beyond," a decadal survey that generated consensus recommendations from Earth and environmental science and applications community for a renewed program of earth observations. The new report finds that although NASA responded favorably and aggressively to the decadal survey, the required budget was not achieved, greatly slowing progress. Changes in program scope without commensurate funding, directed by the Office of Management and Budget and by Congress, also slowed progress. A further impediment, the report says, is the absence of a highly reliable and affordable medium-class launch capability.
Despite these challenges, NASA has been successful in launching some of the missions in development when the survey report was published. It has also made notable progress in establishing the "Venture-class" program, as recommended in the decadal survey. The suborbital program and the airborne science program are additional areas where significant progress is being made. In accord with the decadal survey's recommendations, NASA also aggressively pursued international partnerships to mitigate shortfalls and stretch resources.
In the near term, the report concludes, budgets for NASA's earth science program will remain inadequate to meet pressing national needs. Therefore the agency should focus on two necessary actions: defining and implementing a cost-constrained approach to mission development, and identifying and empowering a cross-mission earth system science and engineering team to advise on the execution of decadal survey missions.
The report also reviews the state of NOAA's satellite earth observation program, an integral part of the decadal survey's overall strategy and tied to the success of NASA's program. Budget shortfalls and cost overruns in NOAA's next generation of polar environmental satellites account for the slow rate of progress. An interagency framework, recommended in the decadal survey to assist NASA and NOAA in optimizing resources, has yet to be realized. This framework is even more crucial now that both agencies face fiscal constraints, and its importance is reiterated in the present report.

Reference: http://www.nap.edu/catalog.php?record_id=13405  , http://www.sciencedaily.com/releases/2012/05/120502123437.htm

Eating Fish, Chicken, Nuts May Lower Risk of Alzheimer's Disease

A new study suggests that eating foods that contain omega-3 fatty acids, such as fish, chicken, salad dressing and nuts, may be associated with lower blood levels of a protein related to Alzheimer's disease and memory problems. The research is published in the May 2, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"While it's not easy to measure the level of beta-amyloid deposits in the brain in this type of study, it is relatively easy to measure the levels of beta-amyloid in the blood, which, to a certain degree, relates to the level in the brain," said study author Nikolaos Scarmeas, MD, MS, with Columbia University Medical Center in New York and a member of the American Academy of Neurology.
For the study, 1,219 people older than age 65, free of dementia, provided information about their diet for an average of 1.2 years before their blood was tested for the beta-amyloid. Researchers looked specifically at 10 nutrients, including saturated fatty acids, omega-3 and omega-6 polyunsaturated fatty acids, mono-unsaturated fatty acid, vitamin E, vitamin C, beta-carotene, vitamin B12, folate and vitamin D.
The study found that the more omega-3 fatty acids a person took in, the lower their blood beta-amyloid levels. Consuming one gram of omega-3 per day (equal to approximately half a fillet of salmon per week) more than the average omega-3 consumed by people in the study is associated with 20 to 30 percent lower blood beta-amyloid levels.
Other nutrients were not associated with plasma beta-amyloid levels. The results stayed the same after adjusting for age, education, gender, ethnicity, amount of calories consumed and whether a participant had the APOE gene, a risk factor for Alzheimer's disease.
"Determining through further research whether omega-3 fatty acids or other nutrients relate to spinal fluid or brain beta-amyloid levels or levels of other Alzheimer's disease related proteins can strengthen our confidence on beneficial effects of parts of our diet in preventing dementia," said Scarmeas.
The study was supported by the National Institute on Aging.

reference: http://www.sciencedaily.com/releases/2012/05/120502184831.htm

Electronic Nanotube Nose out in Front

ScienceDaily (May 2, 2012) — Chemical sensors are exceedingly good at detecting a single substance or a class of chemicals, even at highly rarified concentrations. Biological noses, however, are vastly more versatile and capable of discriminating subtle cues that would confound their engineered counterparts. Unfortunately, even highly trained noses do leave a certain ambiguity when relaying a signal and are not particularly suited for work in specialized situations like operating rooms. A new DNA-based chemical sensor appears to be both extremely sensitive and discerning, making it an important stride on the path to an all-electronic nose.

A team of researchers report in a paper published in the American Institute of Physics' journal AIP Advances that specially tailored strands of DNA attached to carbon nanotubes can tell the difference between very similar molecules, even those that have an identical chemical makeup. "We're trying to develop this into an electronic nose system," says A.T. Charlie Johnson, a physicist at the University of Pennsylvania and study co-author. "We used this system to distinguish between optical isomers, molecules that are nearly identical except that one is structurally reversed -- a mirror image."
The system works by affixing DNA strands to carbon nanotubes, which are excellent electrical conductors. The DNA strands have been fine-tuned to respond to particular chemicals, so when strands come in contact with a target chemical -- even at very low concentrations -- it produces a measurable electrical signal along the nanotube. The sensors were able to check for molecules that differ by as little as one carbon atom. Though the researchers are not the first to observe this effect, they have achieved an unprecedented level of differentiation for an all-electronic chemical detector. "What I'm focusing on is the size of the difference in the signal," says Johnson.
The researchers are next interested in creating something akin to an actual electronic nose consisting of many individual DNA-based sensors performing the same role as an olfactory receptor. The goal is to have a system that is highly versatile and sensitive with wide-scale applications. For example, the chemical dimethylsulfone is associated with skin cancer. The human nose cannot detect this volatile but it could be detected with the new sensor at concentrations as low as 25 parts per billion.
This work was supported by the Army Research Office and by the Nano/Bio Interface Center through the National Science Foundation.

Reference: http://www.sciencedaily.com/releases/2012/05/120502112910.htm