Month: December 2014

WASHINGTON (TIP): Even as astronomers search for extraterrestrial life in planets that look a lot like Earth because of presence of oxygen, some such planets may not be habitable because of intense heat during their formative years, says a study. Some planets close to lowmass stars – prime targets in the search for extraterrestrial life – likely had their water and atmospheres burned away when they were still forming, the researchers found through computer simulations.

Low-mass stars, also called M dwarfs, are smaller than the sun, and also much less luminous, so their habitable zone tends to be fairly close in. “All stars form in the collapse of a giant cloud of interstellar gas, which releases energy in the form of light as it shrinks,” said Rodrigo Luger from University of Washington. “But because of their lower masses, and therefore lower gravities, M dwarfs take longer to fully collapse – on the order of many hundreds of millions of years,” Luger explained. Planets around these stars can form within 10 million years, so they are around when the stars are still extremely bright. “And that is not good for habitability, since these planets are going to initially be very hot, with surface temperatures in excess of a thousand degrees.

When this happens, your oceans boil and your entire atmosphere becomes steam,” Luger added. The researchers noted that M dwarf stars emit a lot of Xray and ultraviolet light, which heats the upper atmosphere to thousands of degrees. A side effect of this process could lead to huge oxygen build-up in the planets. “Because of the oxygen they build up, they could look a lot like Earth from afar – but if you look more closely you will find that they are really a mirage; there is just no water there,” Luger added.

CAPE CANAVERAL (TIP): Wind gusts and sticky fuel valves conspired to keep Nasa’s new Orion spacecraft on the launch pad on December 5, delaying a crucial test flight meant to revitalize human exploration. The space agency’s new countdown clock got a workout as problem after problem cropped up in the final four minutes, and the count switched back and forth. A stray boat in the launch-danger zone kicked things off badly.

Then excessive wind twice halted the countdown, followed by valve trouble on the unmanned Delta IV rocket that could not be fixed in time. Declining battery power in the rocket’s video camera system reinforced the decision to quit for the day. Orion is how Nasa hopes to one day send astronauts to Mars. This inaugural flight, while just 4 hours, will send the unmanned capsule 3,600 miles (5,800 kilometres) into space. It’s the first attempt to send a spacecraft capable of carrying humans beyond a couple hundred miles of Earth since the Apollo moon program.

The ultimate goal, in the decades ahead, is to use Orion to carry people to Mars and back. Nasa anticipated 26,000 guests for the historic send-off — the roads leading into Kennedy Space Center were packed well before dawn — and the atmosphere was reminiscent of the shuttle-flying days. “Go Orion!!” urged a hotel billboard in nearby Cocoa Beach. The launch would have been special for another reason: Nasa launch commentator Mike Curie noted that it was the 16th anniversary of the launch of the first US piece of the International Space Station, by shuttle Endeavour.

“That was the beginning of the space station, and today is the dawn of Orion,” he said. Orion is aiming for two orbits on this inaugural run. On the second lap around the home planet, the spacecraft should reach a peak altitude of 3,600 miles, high enough to ensure a re-entry speed of 20,000mph (32,200kmph)and an environment of 4,000 degrees (2,200 celsius). Splashdown will be in the Pacific off the Mexican Baja coast, where Navy ships already are waiting. Nasa’s Mission Control in Houston was all set to oversee the entire 4{- hour operation once the rocket was in flight.

The flight program was loaded into Orion’s computers well in advance, allowing the spacecraft to fly essentially on autopilot. Flight controllers could intervene in the event of an emergency breakdown. The spacecraft is rigged with 1,200 sensors to gauge everything from heat to vibration to radiation. At 11 feet (3.4 meters) tall with a 16.5-foot (5-meter) base, Orion is bigger than the old-time Apollo capsules and, obviously, more advanced. As Nasa’s program manager Mark Geyer noted, “The inside of the capsule is totally different.”

LONDON (TIP): Scientists have confirmed that eating late at night causes weight gain suggesting that restricting eating hours could help fight high cholesterol, diabetes and obesity. Confining meals to a 12 hour window, such as 8am to 8pm, and fasting for the remaining day, appears to make a huge difference to whether fat is stored, or burned up by the body.

A new study by researchers at the Salk Institute cautions against an extended period of snacking, suggesting instead that confining caloric consumption to an 8 to 12 hour period — as people did just a century ago-might stave off high cholesterol, diabetes and obesity. The results add to mounting evidence suggesting that it’s not just what we eat but when we eat it that matters to our health. Although the intervention has not yet been tested in humans, it has already gained visibility as a potential weight loss method – and, in mice, it may reveal what causes obesity and related conditions in the first place.

In 2012, Satchidananda Panda, a Salk associate professor, showed that mice which were fed a high-fat diet, but allowed access to that diet for only eight hours per day, were healthier and slimmer than mice given access to the same food for the whole day, even though the two groups consumed the same number of calories. The new study shows the benefits of time restriction is surprisingly more profound than initially thought and can reverse obesity and diabetes in animal models.

Panda says, “These days, with the abundance of artificial light, TV, tablets and smartphones, adults and children alike are burning the midnight oil. What they are not burning is calories: with later bedtimes comes the tendency to eat.” The authors demonstrated that time restriction better synchronizes the function of hundreds of genes and gene products in our body with the predictable time of eating. Panda and his researchers, who study the body’s 24-hour rhythms, wanted to know how forgiving time-restricted feeding was.

In the new study, Panda’s group subjected nearly 400 mice, ranging from normal to obese, to various types of diets and lengths of time restrictions. They found that the benefits of time-restricted feeding showed up regardless of the weight of the mouse, type of diet and length of the time restriction (to some degree). Regardless of whether their diets were high in fat, fat and sucrose or just fructose, mice that were given time restrictions of 9 to 12 hours-and consumed the same amount of daily calories as their unrestricted counterpartsgained less weight than the controls, researchers found.

In particular, variations in the time window in which the mice were allowed to eat a highfat diet-including 9-, 10- and 12-hour periods-all resulted in similarly lean mice. For a 15-hour group, the benefits conferred by time restriction became more modest. Researchers gave some of the time-restricted mice a respite on weekends, allowing them free access to high-fat meals for these two days.

These mice had less fat mass and gained less weight than the mice given a freely available, high-fat diet the whole time. In fact, the mice that were freely fed just on weekends looked much the same as mice given access to food 9 or 12 hours a day for seven days a week, suggesting that the diet can withstand some temporary interruptions. “The fact that it worked no matter what the diet, and the fact that it worked over the weekend and weekdays, was a very nice surprise,” says the study’s first author Amandine Chaix, a postdoctoral researcher in Panda’s lab. More importantly, for the mice that had already become obese by eating a freely available high-fat diet, researchers restricted their food access to a nine-hour window.

Although the mice continued to consume the same number of calories, they dropped body weight by five percent within a few days. Importantly, eating this way prevented the mice from further weight gain (by about 25 percent by the end of the 38-week study) compared to the group kept on the freely available high-fat diet. The group also compared mice given a more balanced diet, showing that the timerestricted mice had more lean muscle mass than their unfettered littermates. It’s an interesting observation that although the mice on a normal diet did not lose weight, they changed their body composition,” Panda says. “That brings up the question—what happens? Are these mice maintaining their muscle mass which might have been lost with free feeding, or are they gaining muscle mass?”