Nuclear Radiation Affects Sex of Babies, Study Suggests

Ionizing radiation is not without danger to human populations. Indeed, exposure to nuclear radiation leads to an increase in male births relative to female births, according to a new study by Hagen Scherb and Kristina Voigt from the Helmholtz Zentrum München.

Their work shows that radiation from atomic bomb testing before the Partial Test Ban Treaty in 1963, the Chernobyl accident, and from living near nuclear facilities, has had a long-term negative effect on the ratio of male to female human births (sex odds). The research is published in the June issue of Springer's journal Environmental Science and Pollution Research.

Ionizing radiation from nuclear activity is known to have mutagenic properties and is therefore likely to have detrimental reproductive effects. It is thought that it may cause men to father more sons and mothers to give birth to more girls. Scherb and Voigt look at the long-term effects of radiation exposure on sex odds -- a unique genetic indicator that may reveal differences in seemingly normal as well as adverse pregnancy outcomes between maternal exposure and paternal exposure. In particular, they focus on sex odds data with respect to global atmospheric atomic bomb test fallout in Western Europe and the US, fallout due to nuclear accidents in the whole of Europe, and radioactive releases from nuclear facilities under normal operating conditions in Switzerland and Germany.

Their analyses show a significant male-female gap in all three cases:

• Increases in male births relative to female births in Europe and the US between 1964-1975 are a likely consequence of the globally emitted and dispersed atmospheric atomic bomb test fallout, prior to the test ban in 1963, that affected large human populations overall after a certain delay.
• There was a significant jump of sex odds in Europe in the year 1987 following Chernobyl, whereas no such similar effect was seen in the US, which was less exposed to the consequences of the catastrophe.
• Among populations living in the proximity of nuclear facilities (within 35km or 22 miles), the sex odds also increased significantly in both Germany and Switzerland during the running periods of those facilities.

Taken together these findings show a long-term, dose-dependent impact of radiation exposure on human sex odds, proving cause and effect. What is less clear is whether this increase in male births relative to female births is the result of a reduced frequency of female births or an increased number of male births. The authors estimate that the deficit of births and the number of stillborn or impaired children after the global releases of ionizing radiation amount to several millions globally.

Scherb and Voigt conclude: "Our results contribute to disproving the established and prevailing belief that radiation-induced hereditary effects have yet to be detected in human populations. We find strong evidence of an enhanced impairment of humankind's genetic pool by artificial ionizing radiation."

Nanoengineers Invent New Biomaterial That More Closely Mimics Human Tissue

A new biomaterial designed for repairing damaged human tissue doesn't wrinkle up when it is stretched. The invention from nanoengineers at the University of California, San Diego marks a significant breakthrough in tissue engineering because it more closely mimics the properties of native human tissue.

Shaochen Chen, professor in the Department of NanoEngineering at the UC San Diego Jacobs School of Engineering, hopes future tissue patches, which are used to repair damaged heart walls, blood vessels and skin, for example, will be more compatible with native human tissue than the patches available today. His findings were published in a recent issue of the journal Advanced Functional Materials.

The new biomaterial was created using a new biofabrication platform that Chen is developing under a four-year, $1.5 million grant from the National Institutes of Health. This biofabrication technique uses light, precisely controlled mirrors and a computer projection system -- shined on a solution of new cells and polymers -- to build three-dimensional scaffolds with well-defined patterns of any shape for tissue engineering.

"We are also exploring other opportunities," said Chen. "It's a new material. I think it's just a matter of time before more people will pick up and find applications for it in defense, energy and communications, for instance."

Although Chen's team is focused on creating biological materials, he said the manufacturing technology could be used to engineer many other kinds of materials including metal parts used in ships and spacecraft, for example.

Shape turned out to be essential to the new material's mechanical property. While most engineered tissue is layered in scaffolds that take the shape of circular or square holes, Chen's team created two new shapes called "reentrant honeycomb" and "cut missing rib." Both shapes exhibit the property of negative Poisson's ratio (i.e. not wrinkling when stretched) and maintain this property whether the tissue patch has one or multiple layers. One layer is double the thickness of a human hair, and the number of layers used in a tissue patch depends on the thickness of the native tissue that doctors are trying to repair. A single layer would not be thick enough to repair a heart wall or skin tissue, for example. The next phase of research will involve working with the Department of Bioengineering at the Jacobs School of Engineering to make tissue grafts to repair damaged blood vessels.

The team includes postdoctoral researchers in multiple disciplines: David Fozdar with the University of Texas at Austin, Department of Mechanical Engineering; Li-Hsin Han with the Stanford University School of Medicine, Department of Orthopeadic Surgery; and Pranav Soman and Jim Woo Lee at the UCSD Jacobs School of Engineering Department of NanoEngineering.

Drug May Help Overwrite Bad Memories

Recalling painful memories while under the influence of the drug metyrapone reduces the brain's ability to re-record the negative emotions associated with them, according to University of Montreal researchers at the Centre for Studies on Human Stress of Louis-H. Lafontaine Hospital. The team's study challenges the theory that memories cannot be modified once they are stored in the brain.

Metyrapone is a drug that significantly decreases the levels of cortisol, a stress hormone that is involved in memory recall," explained lead author Marie-France Marin. Manipulating cortisol close to the time of forming new memories can decrease the negative emotions that may be associated with them. "The results show that when we decrease stress hormone levels at the time of recall of a negative event, we can impair the memory for this negative event with a long-lasting effect," said Dr. Sonia Lupien, who directed the research.

Thirty-three men participated in the study, which involved learning a story composed of neutral and negative events. Three days later, they were divided into three groups -- participants in the first group received a single dose of metyrapone, the second received double, while the third were given placebo. They were then asked to remember the story. Their memory performance was then evaluated again four days later, once the drug had cleared out.. "We found that the men in the group who received two doses of metyrapone were impaired when retrieving the negative events of the story, while they showed no impairment recalling the neutral parts of the story," Marin explained. "We were surprised that the decreased memory of negative information was still present once cortisol levels had returned to normal."

The research offers hope to people suffering from syndromes such as post-traumatic stress disorder. "Our findings may help people deal with traumatic events by offering them the opportunity to 'write-over' the emotional part of their memories during therapy," Marin said. One major hurdle, however, is the fact that metyrapone is no longer commercially produced. Nevertheless, the findings are very promising in terms of future clinical treatments. "Other drugs also decrease cortisol levels, and further studies with these compounds will enable us to gain a better understanding of the brain mechanisms involved in the modulation of negative memories

Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star

Tiny crystals of a green mineral called olivine are falling down like rain on a burgeoning star, according to observations from NASA's Spitzer Space Telescope.

This is the first time such crystals have been observed in the dusty clouds of gas that collapse around forming stars. Astronomers are still debating how the crystals got there, but the most likely culprits are jets of gas blasting away from the embryonic star.

"You need temperatures as hot as lava to make these crystals," said Tom Megeath of the University of Toledo in Ohio. He is the principal investigator of the research and the second author of a new study appearing in Astrophysical Journal Letters. "We propose that the crystals were cooked up near the surface of the forming star, then carried up into the surrounding cloud where temperatures are much colder, and ultimately fell down again like glitter."

Spitzer's infrared detectors spotted the crystal rain around a distant, sun-like embryonic star, or protostar, referred to as HOPS-68, in the constellation Orion.

The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals and can be found everywhere from a periodot gemstone to the green sand beaches of Hawaii to remote galaxies. NASA's Stardust and Deep Impact missions both detected the crystals in their close-up studies of comets.

"If you could somehow transport yourself inside this protostar's collapsing gas cloud, it would be very dark," said Charles Poteet, lead author of the new study, also from the University of Toledo. "But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a black, dusty backdrop."

Forsterite crystals were spotted before in the swirling, planet-forming disks that surround young stars. The discovery of the crystals in the outer collapsing cloud of a proto-star is surprising because of the cloud's colder temperatures, about minus 280 degrees Fahrenheit (minus 170 degrees Celsius). This led the team of astronomers to speculate the jets may in fact be transporting the cooked-up crystals to the chilly outer cloud.

The findings might also explain why comets, which form in the frigid outskirts of our solar system, contain the same type of crystals. Comets are born in regions where water is frozen, much colder than the searing temperatures needed to form the crystals, approximately 1,300 degrees Fahrenheit (700 degrees Celsius). The leading theory on how comets acquired the crystals is that materials in our young solar system mingled together in a planet-forming disk. In this scenario, materials that formed near the sun, such as the crystals, eventually migrated out to the outer, cooler regions of the solar system.

Poteet and his colleagues say this scenario could still be true but speculate that jets might have lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the outer regions of our forming solar system. Eventually, the crystals would have been frozen into comets. The Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, also participated in the study by characterizing the forming star.

"Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began its warm mission.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

Astronomers Unveil Most Complete 3-D Map of Local Universe

Astronomers have unveiled the most complete 3-D map of the local universe (out to a distance of 380 million light-years) ever created. Taking more than 10 years to complete, the 2MASS Redshift Survey (2MRS) also is notable for extending closer to the Galactic plane than previous surveys -- a region that's generally obscured by dust.

Karen Masters (University of Portsmouth, UK) presented the new map May 25, 2011 in a press conference at the 218th meeting of the American Astronomical Society.

"The 2MASS Redshift Survey is a wonderfully complete new look at the local universe -- particularly near the Galactic plane," Masters said. "We're also honoring the legacy of the late John Huchra, an astronomer at the Harvard-Smithsonian Center for Astrophysics, who was a guiding force behind this and earlier galaxy redshift surveys."

A galaxy's light is redshifted, or stretched to longer wavelengths, by the expansion of the universe. The farther the galaxy, the greater its redshift, so redshift measurements yield galaxy distances -- the vital third dimension in a 3-D map.

2MRS chose galaxies to map from images made by the Two-Micron All-SkySurvey (2MASS). This survey scanned the entire sky in three near-infrared wavelength bands. Near-infrared light penetrates intervening dust better than visible light, allowing astronomers to see more of the sky. But without adding redshifts, 2MASS makes only a 2-D image. Some of the galaxies mapped had previously-measured redshifts, and Huchra started painstakingly measuring redshifts for the others in the late 1990s using mainly two telescopes: one at the Fred Lawrence Whipple Observatory on Mt. Hopkins, AZ, and one at the Cerro Tololo Inter-American Observatory in Chile. The last observations were completed by 2MRS observers on these telescopes shortly after Huchra's death in October 2010.

Robert Kirshner, Huchra's colleague at the Center for Astrophysics (CfA), said, "John loved doing redshift surveys and he loved the infrared. He had the insight to tell when infrared technology, formerly the province of the experts, was ripe for routine use in a big project."

"John was instrumental in setting up the 2MASS telescope at Mount Hopkins, seeing the infrared side of the project through, and making a much more complete survey of the local universe. It's a wonderful tribute to John that his colleagues have finished the infrared-selected galaxy redshift survey that John started," he added.

The 2MRS mapped in detail areas previously hidden behind our Milky Way to better understand the impact they have on our motion. The motion of the Milky Way with respect to the rest of the universe has been a puzzle ever since astronomers were first able to measure it and found it couldn't be explained by the gravitational attraction from any visible matter. Massive local structures, like the Hydra-Centaurus region (the "Great Attractor") were previously hidden almost behind the Milky Way but are now shown in great detail by 2MRS.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Students Struggling With Math May Have a Neurocognitive Disorder Called Dyscalculia: Disorder Affects Roughly as Many People as Dyslexia

Students who struggle to learn mathematics may have a neurocognitive disorder that inhibits the acquisition of basic numerical and arithmetic concepts, according to a new paper. Specialised teaching for individuals with dyscalculia, the mathematical equivalent of dyslexia, should be made widely available in mainstream education, according to a review of current research published in the journal Science.

Science can't design away tornadoes' deadly threat

WASHINGTON – Storm science has greatly improved tornado warnings in recent years. But if that's led anyone into a sense of security, that feeling has taken a beating in recent weeks.

Super Outbreak 2011, on April 25-28, killed more than 300 people in the South and Midwest. Less than a month later, a devastating tornado took more than 130 lives around Joplin, Mo. This is now the deadliest year for tornadoes since 1950, based on an assessment of National Weather Service figures.

This despite warnings of as much as 20 minutes, thanks to improved weather radar installed across the country in the 1990s. Before that, tornado warnings often weren't issued until a twister was sighted on the ground.

Scientists see a variety of factors that helped make this year's twisters deadlier — from La Nina to public complacency, from global warming to urban sprawl.

"We thought for the longest time physical science could get us by ... that we could design out of disaster," said meteorology professor Walker Ashley of Northern Illinois University. Now scientists are finding they need to take human nature into account.

What is clear is that certain factors add to the risk of death. The most vulnerable folks are those living in mobile homes and houses without basements. For a variety of reasons, a lot of homes don't have basements.

Twisters occurring on weekends — like the Joplin tornado — and at night tend to be greater killers because they catch people at home. At night, twisters are harder to see and sleeping people may not hear a warning.

Those less likely to be killed in a storm tend to be more educated and to have a plan in place beforehand.

In Sedalia, Mo., 30-year-old Sean McCabe had the right idea when the tornado struck, heading to the basement. He said the storm shoved him down the final flight of steps. He had scrapes and cuts on his hands, wrists, back and feet. Blood was visible in the house, and much of the roof of the house was gone.

"I saw little debris and then I saw big debris, and I'm like OK, let's go," said McCabe.

Having a plan was a lifesaver for Tuscaloosa's LaRocca Nursing Home in Alabama. As the storm howled, four dozen residents massed in the hallways as trees crashed down and a cloud of dust rained upon them. When the dust settled, the staff realized their drills had paid off. Not one patient was killed, and the worst injury among them was a bruise.

Hundreds have not been so lucky, with more than 500 deaths and counting so far this year, a toll not seen in more than a half-century.

The toll for 2011 is now at least 520 people, exceeding the previous highest recorded death toll in a single year of 519 in 1953. There were deadlier storms before 1950, but those counts were based on estimates and not on precise figures.

The National Weather Service said 58 tornadoes touched down in Alabama on April 27, killing 238 people in that state alone and injuring thousands. Scores died in other states from twisters spawned by the same storm system. Put together, emergency management officials say the twisters left a path of destruction 10 miles wide and 610 miles long, or about as far as a drive from Birmingham to Columbus, Ohio.

Statewide, Alabama officials estimate there was enough debris to stack a football field a mile high with rubble.

Contributing to the massive loss of life is the growth of urban areas, suggested Marshall Shepherd, a professor of atmospheric science at the University of Georgia.

"Historically, the central business districts of cities have not been hit that frequently," he explained. But as you increase the land area covered by homes and businesses, he said, "you're increasing the size of the dartboard."

An expanding population does increase exposure to the danger, agreed Ashley, who fears deaths could begin to rise in the future as a result of sprawl and more people living in vulnerable residences such as mobile homes.

If the Tuscaloosa and Joplin tornadoes had each been a few miles to the south, on farmland, little would be heard about them, Ashley said, but when extremely violent tornadoes mingle with urban sprawl "you're going to have a disaster."

"I hope this will be an outlier year, very much like Katrina was to hurricanes," he said in a telephone interview from a field trip to chase tornadoes.

But no one can guarantee that, and weather experts are becoming increasingly concerned about how people respond to tornado warnings.

"A lot of it is complacency," Ashley said. "The population seems to be becoming desensitized to nature. I don't know why."

Studies have shown that 15 to 20 minutes is the most effective amount of warning time, and longer warning times can increase deaths. Weather experts aren't sure why, but worry that people think that if a twister hasn't appeared in a certain amount of time, it must have been a false alarm.

Yet a long-track tornado can be on the ground for 30 miles.

"If you have a basement, you don't need 20 minutes warning, but if you are in a mobile home park you may need more than 20 minutes to find a shelter," commented Alan W. Black, a University of Georgia doctoral student and co-author with Ashley of a recent study of tornado and wind fatalities.

Jerry Brotzge, a research scientist at the Center for Analysis & Prediction of Storms, University of Oklahoma, said many people who hear warnings will look outside to see if they can see the tornado — "they need some kind of confirmation, they want to see it."

But the Joplin tornado was at least partly rain-wrapped, meaning that a powerful rainstorm obscured it from some directions and "they wouldn't have seen it coming."

"Even when people are sheltered in their homes, if they are not underground they can die," Brotzge added.

But asking people to evacuate an area is also a difficult decision, he said, "what if you have a traffic jam and the tornado hits that."

Ashley concluded: "The take-home is, people have to take personal responsibility for their lives."

Why there have been so many tornado threats this year is harder to say.

Viewing pictures of the tornado aftermath it's hard to overestimate the power of such storms, and records bear out how strong they can be.

"You see pictures of World War II, the devastation and all that with the bombing. That's really what it looked like," said Kerry Sachetta, the principal of a flattened Joplin High School. "I couldn't even make out the side of the building. It was total devastation in my view. I just couldn't believe what I saw."

And that movie image a few years ago was no joke: A cow was transported 10 miles by a twister in Iowa in 1878 and a tornado in Minnesota moved a headstone three miles in 1886.

One Joplin resident said a picture that was sucked off his house's wall was found in Springfield, 70 miles away. An insurance policy was found more than 40 miles from its original residence in Oklahoma in 1957 and a 210-mile trip was taken by a canceled check in Nebraska in 1915, according to a study several years ago by researchers at the University of Oklahoma and St. Louis University.

Typically, tornadoes spawn in the clash between warm, moist air from the Gulf of Mexico and cooler, dry air from the north and west — conditions that mark Tornado Alley in the Midwest and South, the most common breeding grounds for twisters.

Factors in this year's excess may include La Nina, a periodic cooling of the tropical Pacific Ocean which can affect weather worldwide. In a La Nina year there tend to be more tornadoes than average. If that is a factor, the good news is that La Nina is weakening and is expected to end in a month or so.

The meandering jet stream high in the atmosphere that directs the movements of weather also has been in a pattern that encourages warm Gulf air to move in and clash with drier air masses.

While studies of global warming have suggested it could cause more and stronger storms, National Weather Service Director Jack Hayes isn't ready to blame climate change — at least not yet — saying it's too soon to link individual events with the ongoing warming.

Tornado researcher Howard B. Bluestein of the University of Oklahoma says his best guess is this unusual outburst of twisters is due to natural variability of the weather.

"Sometimes you get a weather pattern in which the ingredients for a tornado are there over a wide area and persist for a long time. That's what we're having this year," he said.

"If we see this happen next year and the following year and the following year," then maybe climate change could be to blame, he said.

Whatever the reasons it's an extraordinary year for tornadoes and the worst may not be over. May is usually the peak month, but June traditionally gets lots of twisters, and they can occur in any month.

"You can never completely breathe easy," concluded Russell Schneider, director of the government's Storm Prediction Center in Norman, Okla.

Astronauts pack up on next-to-last shuttle flight

CAPE CANAVERAL, Fla. – Endeavour's astronauts took care of some last-minute space station chores Saturday before packing up to come home and end the next-to-last shuttle flight.

The space shuttle and its crew of six will depart the International Space Station late Sunday night. They worked to repair one of the space station's air purifiers and straightened out the suits that were used in four spacewalks. The final spacewalk of the mission, on Friday, completed the U.S. portion of station construction.

Now that the spacewalks are over, Mission Control told the astronauts they "can bask in the glow of a job well done."

Shuttle pilot Gregory Johnson said it will be bittersweet to leave. He and his crewmates installed a $2 billion physics experiment at the orbiting outpost, as well as an extension pole and a platform full of spare parts.

"It's been a fantastic mission," Johnson said in a series of news interviews. "It's the sort of mission that astronauts dream of having."

Johnson said he and his colleagues are spending their final hours at the space station doing "everything we can do to help the space station out before we return to Earth." The station is so big now, he said, that sometimes he takes a wrong turn and finds himself in the wrong chamber.

Endeavour is scheduled to return to Florida before dawn Wednesday, 16 days after blasting off.

After Sunday night's undocking, Johnson will guide Endeavour through a victory lap around the space station. He said he'll try to maintain a good position for the shuttle, "so we can get great photos of one of the final fly-arounds of the space station." The shuttle crew also will test out an experimental navigation system for future spacecraft.

This is the final voyage of Endeavour, the youngest in the shuttle fleet. NASA is closing down the shuttle program this summer after 30 years. Atlantis will fly one last time to the space station in July.

Birthplace of 'hot Neptunes' revealed

HOT Neptunes are modestly giant planets that resemble their namesake but orbit close to their stars. But the puzzle is why we see so many hot Neptunes elsewhere but none in our solar system.

The conventional view is that these worlds formed in cold regions far from their stars and then migrated inwards. Now Brad Hansen at the University of California, Los Angeles, and Norm Murray of the Canadian Institute for Theoretical Astrophysics in Toronto say hot Neptunes may have arisen right where they are.

The team modelled a disc of gas and dust around a young star. In work submitted to The Astrophysical Journal, they suggest that if the disc is particularly massive, large cores can form in the inner regions with enough gravity to attract gas, producing hot Neptunes (arxiv.org/abs/1105.2050). However, our sun's disc of gas and dust lacked the mass to build giant worlds in its inner regions. So our Neptune formed far from the sun.

This scenario may explain the large number of hot Neptunes orbiting other stars, says Gregory Laughlin at the University of California, Santa Cruz.

X-ray video reveals how dogs drink

Dogs don't have cheeks to trap liquid, so how do they manage to drink? Alfred Crompton and his team from Harvard University fed a dog some dark broth to observe the process, followed by X-ray video to reveal details of the tongue action.

A recent study showed that cats drink by drawing milk upwards as it clings to the tip of their tongue. Although dogs have a similarly-shaped mouth, it was suggested that unlike cats, they curl their tongues backwards and scoop up liquid.

Crompton's analysis proved that this isn't the case: cats and dogs use the same basic mechanism to lift liquid into their mouths. Although X-ray footage did show that a tiny depression forms on the back surface of a dog's tongue as it lifts up a column of milk, the scooped-up liquid simply spilled out of its mouth. So dogs are simply messier drinkers than cats.

Another difference is that dogs trap milk in tiny folds on the roof of their mouth between sips, allowing them to reach for more milk without losing the previous drops. But even so, it took this dog three laps to finish the contents of a bowl. Drinking just isn't as easy as it seems.