The MIT team's analysis -- led by Ruben Juanes, the ARCO Associate Professor in Energy Studies in the Department of Civil and Environmental Engineering, and part of the doctoral thesis work of graduate students Christopher MacMinn PhD '12 and Michael Szulczewski -- is published this week in the Proceedings of the National Academy of Sciences.

Coal-burning powerplants account for about 40 percent of worldwide carbon emissions, so climate change "will not be addressed unless we address carbon dioxide emissions from coal plants," Juanes says. "We should do many different things" such as developing new, cleaner alternatives, he says, "but one thing that's not going away is coal," because it's such a cheap and widely available source of power.

Efforts to curb greenhouse gases have largely focused on the search for practical, economical sources of clean energy, such as wind or solar power. But human emissions are now so vast that many analysts think it's unlikely that these technologies alone can solve the problem. Some have proposed systems for capturing emissions -- mostly carbon dioxide from the burning of fossil fuels -- then compressing and storing the waste in deep geological formations. This approach is known as carbon capture and storage, or CCS.

One of the most promising places to store the gas is in deep saline aquifers: those more than half a mile below the surface, far below the freshwater sources used for human consumption and agriculture. But estimates of the capacity of such formations in the United States have ranged from enough to store just a few years' worth of coal-plant emissions up to many thousands of years' worth.

The reason for the huge disparity in estimates is twofold. First, because deep saline aquifers have no commercial value, there has been little exploration to determine their extent. Second, the fluid dynamics of how concentrated, liquefied carbon dioxide would spread through such formations is very complex and hard to model. Most analyses have simply estimated the overall volume of the formations, without considering the dynamics of how the CO2 would infiltrate them.......

All evidence points to a white dwarf that feeds off its companions star, gaining mass, growing unstable, and ultimately detonating. But does that white dwarf draw material from a Sun-like star, an evolved red giant star, or from a second white dwarf? Or is something more exotic going on? Clues can be collected by searching for "cosmic crumbs" left over from the white dwarf's last meal.

In two comprehensive studies of SN 2011fe -- the closest Type Ia supernova in the past two decades -- there is new evidence that indicates that the white dwarf progenitor was a particularly picky eater, leading scientists to conclude that the companion star was not likely to be a Sun-like star or an evolved giant.

"It's hard to understand how a white dwarf could eat itself to death while showing such good table manners," said Alicia Soderberg of the Harvard-Smithsonian Center for Astrophysics (CfA).

Soderberg and her colleagues examined SN 2011fe with a suite of instruments in wavelengths ranging from X-rays to radio. They saw no sign of stellar material recently devoured by the white dwarf. Instead, the explosion occurred in a remarkably clean environment.

"This white dwarf was a tidy eater," said Laura Chomiuk of the CfA, lead author of one of the two papers.

Additional studies using NASA's Swift satellite, which examined a large number of more distant Type Ia supernovae, appear to rule out giant stars as companions for the white-dwarf progenitors.

Taken together, these studies suggest that Type Ia supernovae likely originate from a more exotic scenario, possibly the explosive merger of two white dwarfs........

Their study, published March 18th onNature Medicine's website, suggests there might be a way to stimulate expression of that gene to treat obesity caused by uncontrolled eating.

The research team specifically found that a mutation in the brain-derived neurotrophic factor (Bdnf) gene in mice does not allow brain neurons to effectively pass leptin and insulin chemical signals through the brain. In humans, these hormones, which are released in the body after a person eats, are designed to "tell" the body to stop eating. But if the signals fail to reach correct locations in the hypothalamus, the area in the brain that signals satiety, eating continues.

"This is the first time protein synthesis in dendrites, tree-like extensions of neurons, has been found to be critical for control of weight," says the study's senior investigator, Baoji Xu, Ph.D., an associate professor of pharmacology and physiology at Georgetown.

"This discovery may open up novel strategies to help the brain control body weight," he says.

Xu has long investigated the Bdnf gene. He has found that the gene produces a growth factor that controls communication between neurons.

For example, he has shown that during development, BDNF is important to the formation and maturation of synapses, the structures that permit neurons to send chemical signals between them. The Bdnf gene generates one short transcript and one long transcript. He discovered that when the long-form Bdnf transcript is absent, the growth factor BDNF is only synthesized in the cell body of a neuron but not in its dendrites. The neuron then produces too many immature synapses, resulting in deficits in learning and memory in mice........

Research, led by experts at Newcastle University, UK, and published March 18 in the journal Nature Geoscience, reveals that Earth's early atmosphere periodically flipped from a hydrocarbon-free state into a hydrocarbon-rich state similar to that of Saturn's moon, Titan.

This switch between "organic haze" and a "haze-free" environment was the result of intense microbial activity and would have had a profound effect on the climate of Earth system.

Similar to the way scientists believe our climate behaves today, the team say their findings provide us with an insight into Earth's surface environment prior to oxygenation of the planet.

Study lead Dr Aubrey Zerkle, based in the School of Civil Engineering and Geosciences at Newcastle University, explains: "Models have previously suggested that Earth's early atmosphere could have been warmed by a layer of organic haze.

"Our geochemical analyses of marine sediments from this time period provide the first evidence for such an atmosphere.

"However, instead of evidence for a continuously 'hazy' period we found the signal flipped on and off, in response to microbial activity.

"This provides us with insight into Earth's surface environment prior to oxygenation of the planet and confirms the importance of methane gas in regulating the early atmosphere."

Dr Zerkle, working along with Dr James Farquhar at the University of Maryland, USA, and Dr Simon Poulton at Newcastle University, UK, analysed the geochemistry of marine sediments deposited between 2.65 and 2.5 billion years ago in what is now South Africa......

"Our results show that the final distribution of planets does not vary smoothly with distance from the star, but instead has clear 'deserts' -- deficits of planets -- and 'pile-ups' of planets at particular locations," said Ilaria Pascucci, an assistant professor at the University of Arizona's Lunar and Planetary Laboratory.

"Our models offer a plausible explanation for the pile-ups of giant planets observed recently detected in exoplanet surveys," said Richard Alexander of the University of Leicester in the United Kingdom.

Alexander and Pascucci identified high-energy radiation from baby sun-like stars as the likely force that carves gaps in protoplanetary disks, the clouds of gas and dust that swirl around young stars and provide the raw materials for planets. The gaps then act as barricades, corralling planets into certain orbits.

The exact locations of those gaps depend on the planets' mass, but they generally occur in an area between 1 and 2 astronomical units from the star. One astronomical unit, or AU, marks the average distance from Earth to the sun. The findings are to be published in the journal Monthly Notices of the Royal Astronomical Society........

Nearly 48 billion bases of DNA, the genetic building blocks, were collected in the stools of 12 individuals. The researchers then assembled the blocks like puzzle pieces to recreate whole virus genomes. Hundreds to thousands of likely distinct viruses were assembled per individual, of which all but one type were bacteriophages -- viruses that infect bacteria -- which the team expected. The other was a human pathogen, a human papillomavirus found in a single individual. Bacteriophages are responsible for the toxic effects of many bacteria, but their role in the human microbiome has only recently started to be studied.

To assess variability in the viral populations among the 12 individuals studied, Bushman's team, led by graduate student Samuel Minot, looked for stretches of bases that varied the most.

Their survey identified 51 hypervariable regions among the 12 people studied, which, to the team's surprise, were associated with reverse transcriptase genes. Reverse transcriptase enzymes, more commonly associated with replication of retroviruses such as HIV, copy RNA into DNA. Of the 51 regions, 29 bore sequence and structural similarity to one well-studied reverse transcriptase, a hypervariable region in theBordetella bacteriophage BPP-1. Bordetella is the microbe that causes kennel cough in dogs.

BPP-1 uses reverse transcriptase and an error-prone copying mechanism to modify a protein to aid in entering and reproducing in a wide array of viral targets. Bushman and colleagues speculate that the newly discovered hypervariable regions could serve a similar function in the human virome, and microbiome, by extension........

Following its discovery by Galileo in January 1610, Io has been the focus of repeated telescopic and satellite scientific observation. These studies have shown that the orbital and gravitational relationships between Io, its sister moons Europa and Ganymede, and Jupiter cause massive, rapid flexing of its rocky crust. These tidal flexures generate tremendous heat within Io's interior, which is released through the many surface volcanoes observed.

"One of the reasons for making this map was to create a tool for continuing scientific studies of Io, and a tool for target planning of Io observations on future missions to the Jupiter system," says David Williams, a faculty research associate in the School of Earth and Space Exploration at ASU, who led the six-year research project to produce the geologic map.

The highly detailed, colorful map reveals a number of volcanic features, including: paterae (caldera-like depressions), lava flow fields, tholi (volcanic domes), and plume deposits, in various shapes, sizes and colors, as well as high mountains and large expanses of sulfur- and sulfur dioxide-rich plains. The mapping identified 425 paterae, or individual volcanic centers. One feature you will not see on the geologic map is impact craters.

"Io has no impact craters; it is the only object in the Solar System where we have not seen any impact craters, testifying to Io's very active volcanic resurfacing," says Williams.

Io is extremely active, with literally hundreds of volcanic sources on its surface. Interestingly, although Io is so volcanically active, more than 25 times more volcanically active than Earth, most of the long-term surface changes resulting from volcanism are restricted to less than 15 percent of the surface, mostly in the form of changes in lava flow fields or within paterae.

"Our mapping has determined that most of the active hot spots occur in paterae, which cover less than 3 percent of Io's surface. Lava flow fields cover approximately 28 percent of the surface, but contain only 31 percent of hot spots," says Williams. "Understanding the geographical distribution of these features and hot spots, as identified through this map, are enabling better models of Io's interior processes to be developed."........

For 27 years, the Concorde provided its passengers with a rare luxury: time saved. For a pricey fare, the sleek supersonic jet ferried its ticketholders from New York to Paris in a mere three-and-a-half hours -- just enough time for a nap and an aperitif. Over the years, expensive tickets, high fuel costs, limited seating and noise disruption from the jet's sonic boom slowed interest and ticket sales. On Nov. 26, 2003, the Concorde -- and commercial supersonic travel -- retired from service.

Since then, a number of groups have been working on designs for the next generation of supersonic jets. Now an MIT researcher has come up with a concept that may solve many of the problems that grounded the Concorde. Qiqi Wang, an assistant professor of aeronautics and astronautics, says the solution, in principle, is simple: Instead of flying with one wing to a side, why not two?

Wang and his colleagues Rui Hu, a postdoc in the Department of Aeronautics and Astronautics, and Antony Jameson, a professor of engineering at Stanford University, have shown through a computer model that a modified biplane can, in fact, produce significantly less drag than a conventional single-wing aircraft at supersonic cruise speeds. The group will publish their results in the Journal of Aircraft.

This decreased drag, according to Wang, means the plane would require less fuel to fly. It also means the plane would produce less of a sonic boom.

"The sonic boom is really the shock waves created by the supersonic airplanes, propagated to the ground," Wang says. "It's like hearing gunfire. It's so annoying that supersonic jets were not allowed to fly over land."

Double the wings, double the fun

With Wang's design, a jet with two wings -- one positioned above the other -- would cancel out the shock waves produced from either wing alone. Wang credits German engineer Adolf Busemann for the original concept. In the 1950s, Busemann came up with a biplane design that essentially eliminates shock waves at supersonic speeds........