Science: February 2015

Friday, 13 February 2015

ScienceDaily: Your source for the latest research news Featured Research from universities, journals, and other organizations A gene that shaped the evolution of Darwin's finches

The medium ground finch (Geospiza fortis) on Daphne Major Island, Galápagos archipelago

Researchers from Princeton University and Uppsala University in Sweden have identified a gene in the Galápagos finches studied by English naturalist Charles Darwin that influences beak shape and that played a role in the birds' evolution from a common ancestor more than 1 million years ago.

The study illustrates the genetic foundation of evolution, including how genes can flow from one species to another, and how different versions of a gene within a species can contribute to the formation of entirely new species, the researchers report in the journal Nature. The study was published online February 11, one day before birthday of Darwin, who studied the finches during the 1835 voyage that would lead him to publish the seminal work on evolution, "On the Origin of Species," in 1859.
"We now know more about the genetic basis for our evolutionary studies, and this is a highly satisfactory, very exciting discovery after all these years," said Peter Grant, Princeton's Class of 1877 Professor of Zoology, Emeritus, and a professor of ecology and evolutionary biology, emeritus. Along with co-author and wife B. Rosemary Grant, a senior biologist in ecology and evolutionary biology, Grant has studied the finches for 40 years on the arid, rocky islands of Daphne Major and Genovesa in the Galápagos archipelago.
The latest study reveals how evolution occurs in halting and disordered steps, with many opportunities for genes to spread in different species and create new lineages. Given the right conditions, such as isolation from the original population and an accumulation of genetic differences, these lineages can eventually evolve into entirely new species.
Working with DNA samples collected by the Grants, researchers at Uppsala identified the gene that influences beak shape by comparing the genomes of 120 birds, all members of the 15 species known as "Darwin's finches." They spotted a stretch of DNA that looked different in species with blunt beaks, such as the large ground finch (Geospiza magnirostris), versus species with pointed beaks, such as the large cactus finch (G. conirostris).
Within that stretch of DNA, the researchers found a gene known as ALX1, which has previously been identified in humans and mice as being associated with the formation of facial features. Mutations that inactivate this gene cause severe birth defects in humans.
"This is an interesting example where mild mutations in a gene that is critical for normal development leads to phenotypic [observable] evolution," said lead researcher Leif Andersson, a professor of functional genomics at Uppsala University, the Swedish University of Agricultural Sciences, and Texas A&M University.
But the most exciting and interesting finding of the study, Andersson said, was that the gene also varied among individuals from the same species. For example, the medium ground finch (G. fortis) species includes some birds with blunt beaks and others with pointed ones.
This finding is significant because it shows how evolution can happen, Peter Grant said. Within a species, when some individuals have a trait that aids their survival -- such as a blunt beak that allows them to crack open tough seed coverings -- they will pass on the genes for that trait to their offspring, whereas individuals with pointed beaks will have died. "This is the genetic variation upon which natural selection can work," he said.
The shape and size of the beak are crucial for finch survival on the islands, which periodically experience extreme droughts, El Niño-driven rains and volcanic activity. The birds use their beaks as tools to crack open the hard and woody outer coverings of seeds, pry insects from twigs, and sip nectar from cactus flowers. In times of drought, a bird that can extract food from multiple sources will survive whereas other birds will not.
During the past four decades, the Grants and their research team have found that beak shape and size played a significant role in the evolution of finch species via natural selection when droughts hit Daphne Major in 1977, 1985 and 2004. "Now we have a genetic underpinning of something we have seen three times during the last 40 years," Rosemary Grant said.
The Nature study also adds to what is known about how genes are transferred from one species to another when individuals from two closely related species mate. Although in many species of birds the resulting chicks would be sterile, the hybrid offspring of Galápagos finches can mate with an individual from either of the two parental species. The resulting chicks will identify with one or the other of the parent species through song and appearance, but they will carry genes from both parents.
Through this process, known as gene flow, or introgression, genetic material can move between species and contribute to the development of new species. The Grants had shown that gene flow has occurred in the finches of Daphne Major during the past 40 years, but the new study found extensive evidence for gene flow throughout the roughly 1 million years that the birds have occupied the archipelago, which has helped the researchers update their understanding of how the lineages diverged over time.
"We've been able to get a much more confident estimate," Peter Grant said, "of which species are old and which are young, and the time course over which evolution happened."

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The above story is based on materials provided by Princeton University. The original article was written by Catherine Zandonella. Note: Materials may be edited for content and length.

Journal Reference:

Sangeet Lamichhaney, Jonas Berglund, Markus Sällman Almén, Khurram Maqbool, Manfred Grabherr, Alvaro Martinez-Barrio, Marta Promerová, Carl-Johan Rubin, Chao Wang, Neda Zamani, B. Rosemary Grant, Peter R. Grant, Matthew T. Webster, Leif Andersson. Evolution of Darwin’s finches and their beaks revealed by genome sequencing. Nature, 2015; DOI: 10.1038/nature14181

Tuesday, 10 February 2015

Dark Matter Could Create Halos of Light Around Galaxies

Messier 101, also known as the Pinwheel Galaxy, seen at ultraviolet and optical wavelengths, in an image taken by ESA's XMM-Newton space telescope. A new study looked at the Pinwheel Galaxy in hopes of finding evidence of dark matter interactions with light.

Dark matter might not be totally dark: A new study reports that if dark matter has even a small interaction with particles of light, it could create a visible glow around galaxies.
Searching for light from the darkest substance in the universe may seem like an oxymoron, but scientists can't rule out the possibility that dark matter and light occasionally interact.
If particles of light can scatter off of dark matter, a new study suggests that this interaction could create "halos of light" around galaxies. The authors of the new work say there are telescopes in operation that could look for this dark matter glow

Looking for a dark matter glow

Roughly 80 percent of the matter in the universe is dark matter. While scientists cannot see dark matter, they know it exists in significant amounts because it exerts a gravitational pull on regular matter. Without dark matter, many galaxies would fly apart, unable to hold all the stars together while spinning at such high speeds.
Scientists have never directly observed dark matter — light appears to pass through it as if it weren't there at all. But it's possible that interactions between dark matter and light occur, but haven't been observed yet.
"The basic idea [of our work] is quite simple: can you say that dark matter is perfectly dark?" Jonathan Davis, a postdoctoral researcher at the Paris Institute of Astrophysics, said. "We want to put a number on how dark it is."
Davis is the lead author on a new paper that suggests that if starlight in galaxies occasionally scatters off dark matter, it would create a halo of light around the galaxy. This effect is the same for light scattering off of regular matter. Fog, for example, can turn a narrow beam of light into a diffuse glow.
"We know dark matter exists around galaxies and we want to ask — if light from the galaxy can scatter off the dark matter, like a dust cloud, can you actually observe this light?" Davis said.
Davis and his co-author, Joseph Silk, an astrophysicist at Johns Hopkins University, went looking for this kind of glow around the galaxy Messier 101, also known as the Pinwheel Galaxy, using data from the Dragonfly Telephoto Array.
"These telescopes were designed to look for diffuse light around galaxies. Not in the context of dark matter, but you can repurpose the data to look for this glow," Davis said. "[The Dragonfly telescopes] are really good at looking for this high contrast between the really bright galactic center and the really dim outskirts of galaxies."
The hunt came up empty — there was no halo in this particular wavelength. But Davis said he hopes the results inspire someone to make a more dedicated search for one of these halos. [8 Baffling Astronomy Mysteries]

A dark particle

Scientists don't know what kind of particle (or particles) make up dark matter, so they don't know for sure what kind of interactions it would have with other particles. These interactions could be somewhat rare.
Particles called neutrinos, for example, shower down on the Earth every second of every day, but for the most part they pass through matter like ghosts. But every once in a while, a neutrino will collide with an atom of regular matter. It's possible that dark matter particles have a similarly low, but not nonexistent, interaction rate with light.
Davis said that if dark matter interacts with light it would have to be made of a charged particle. One of the leading dark matter theories favors weakly interacting massive particles, or WIMPS, which are neutral. But Davis said there are other theories about dark matter that include charged particles.
Davis and Silk are not the only scientists looking for dark matter interactions with light. Carolyn Boehm at the University of Durham (who served as Davis' Ph.D. adviser) has spent years studying how dark matter interactions with light could influence the formation of galaxies and galaxy clusters.
If dark matter interacts with photons and other particles, those interactions could scatter the dark matter. This, in turn, could wipe out structures that trap gas and eventually form galaxies, according to a news release from the Royal Astronomical Society. In September, Boehm co-authored a paper suggesting that dark matter and photon interactions might explain why there are not as many galaxies orbiting the Milky Way, as some scientists expect.
Boehm said in an email to Space.com that she feels the merit of the new work by Davis and Silk lies in the idea of using halos to constrain dark matter interactions with light.
Looking forward, Davis said he hopes the publication of the new work draws attention from other scientists who might like to join the search for light from the darkest substance in the universe

Saturday, 7 February 2015

Gravitational waves from early universe remain elusive

The color scale in this image from the Planck mission represents the emission from dust, a minor but crucial component that pervades our Milky Way galaxy. The texture indicates the orientation of the galactic magnetic field. It is based on measurements of the direction of the polarized light emitted by the dust.

A joint analysis of data from the Planck space mission and the ground-based experiment BICEP2 has found no conclusive evidence of gravitational waves from the birth of our universe, despite earlier reports of a possible detection. The collaboration between the teams has resulted in the most precise knowledge yet of what signals from the ancient gravitational waves should look like, aiding future searches.

Planck is a European Space Agency mission with significant NASA contributions. BICEP2 and its sister project, the Keck Array, are based at the South Pole and funded by the National Science Foundation, also with NASA contributions.
"By analyzing both sets of data together, we could get a more definitive picture of what's going on than we could with either dataset alone," said Charles Lawrence, the U.S. project scientist for Planck at NASA's Jet Propulsion Laboratory, Pasadena, California. "The joint analysis shows that much of the signal detected by BICEP2/Keck is coming from dust in the Milky Way, but we cannot rule out a gravitational wave signal at a low level. This is a good example of how progress is made in science, one step at a time."
Planck and BICEP/Keck were both designed to measure relic radiation emitted from our universe shortly after its birth 13.8 billion years ago. An extraordinary source of information about the universe's history lies in this "fossil" radiation, called the cosmic microwave background (CMB). Planck mapped the CMB over the entire sky from space, while BICEP2/Keck focused on one patch of crisp sky over the South Pole.
In March of 2014, astronomers presented intriguing data from the BICEP2/Keck experiments, finding what appeared to be a possible signal from our universe when it was just born. If the signal were indeed from the early cosmos, then it would have confirmed the presence of ancient gravitational waves. It is hypothesized that these waves were generated by an explosive and very rapid period of growth in our universe, called inflation, which took place when the universe was only a tiny of a fraction of one second old.
Specifically, the BICEP/Keck experiments found evidence for a "curly" pattern of polarized light called B-modes. These patterns would have been imprinted on the CMB light as the gravitational waves slightly squeezed and stretched the fabric of space. Polarization describes a particular property of light. Usually, the electric and magnetic fields carried by light vibrate at all orientations equally, but when they vibrate preferentially in a certain direction, the light is polarized.
"The swirly polarization pattern, reported by BICEP2, was also clearly seen with new data from the Keck Array," said Jamie Bock of the California Institute of Technology in Pasadena, and JPL, a member of both the BICEP2/Keck and Planck teams.
"Searching for this unique record of the very early universe is as difficult as it is exciting, since this subtle signal is hidden in the polarization of the CMB, which itself only represents only a feeble few percent of the total light," said Jan Tauber, the European Space Agency's project scientist for Planck.
One of the trickiest aspects of identifying the primordial B-modes is separating them from those that can be generated much closer to us by interstellar dust in our Milky Way galaxy.
The Milky Way is pervaded by a mixture of gas and dust shining at similar frequencies to those of the CMB, and this closer, or foreground, emission affects the observation of the oldest cosmic light. Very careful data analysis is needed to separate the foreground emission from that of the CMB.
"When we first detected this signal in our data, we relied on models for galactic dust emission that were available at the time," said John Kovac, a co-principal investigator of the BICEP2/Keck collaboration at Harvard University, Cambridge, Massachusetts. "These seemed to indicate that the region of the sky chosen for our observations was relatively devoid of dust."
The BICEP2/Keck experiments collected data at a single microwave frequency, making it difficult to separate the emissions coming from the dust in the Milky Way and the CMB. On the other hand, Planck observed the sky in nine microwave and sub-millimeter frequency channels, seven of which were also equipped with polarization-sensitive detectors. Some of these frequencies were chosen to make measurements of dust in the Milky Way. By careful analysis, these multi-frequency data can be used to separate the various contributions of emissions.
The Planck and BICEP2/Keck teams joined forces, combining the space satellite's ability to deal with foregrounds using observations at several frequencies, with the greater sensitivity of the ground-based experiments over limited areas of the sky.
"The noise in the instruments limits how deeply we can search for a signal from inflation," said Bock. "BICEP2/Keck measured the sky at one wavelength. To answer how much of the signal comes from the galaxy, we used Planck's measurements in multiple wavelengths. We get a big boost by combining BICEP2/Keck and Planck measurements together, the best data currently available."
The final results showed that most of the original BICEP2/Keck B-mode signal, but not necessarily all of it, could be explained by dust in our Milky Way. As for signs of the universe's inflationary period, the question remains open.
The joint Planck/BICEP/Keck study sets an upper limit on the amount of gravitational waves from inflation, which might have been generated at the time but at a level too low to be confirmed by the present analysis.
"The new upper limit on the signal due to gravitational waves agrees well with the upper limit that we obtained earlier with Planck using the temperature fluctuations of the CMB. The gravitational wave signal could still be there, and the search is definitely on," said Brendan Crill, a member of both the BICEP2 and Planck teams from JPL.
A paper on the findings is still under peer review.
NASA and JPL developed detector technology for both the BICEP and Keck Array experiments, as well as for the Planck space telescope. JPL is managed by Caltech for NASA.

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The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.

Astronomers find new details in first known spiral galaxy: Plumes

Case Western Reserve University astronomers found new features on the first-known spiral galaxy, M51a, which has been sketched and photographed for 170 years

Case Western Reserve University astronomers peered deep into space to discover new features of a galaxy that's been sketched and photographed for 170 years.

The researchers were able to see faint plumes extending from the northeast and south of the nearby spiral galaxy M51a, also called the "Whirlpool Galaxy," by taking what is essentially a photograph made by a 20-hour exposure.
The image also provides new details of the linear northwest plume, which itself is nearly 120,000 light-years long, and reveals a lack of stars in a portion of the southeast tail.,
"These features can be used in future modeling to understand the history of M51, when it and its companion galaxy first started to interact," said Aaron Watkins, a PhD student in the department of astronomy at Case Western Reserve and lead author of the study.
Modeling that's already been done fails to match the structures of the system, ages and more.
Watkins worked with the CWRU astronomy professor Chris Mihos and Observatory Manager Paul Harding. The research is published in Astrophysical Journal Letters.
M51a is the first known spiral galaxy, identified and sketched by William Parsons, the Earl of Rosse, in 1845. The whirlpool and its small companion, M51b, are in the hunting dogs constellation, Canes Venatici, about 31 million light years away.
"No professional astronomer we know of has ever taken such a deep image of this galaxy," Watkins said. The images were taken from the CWRU's Burrell Schmidt telescope at Kitt Peak National Observatory near Tucson during February, March and April in 2010 and 2012.
The team aimed the telescope at M51 on moonless nights and exposed its digital camera to the light from the galaxy at 20-minute intervals, recalibrating in between. For a total of 10 hours, light was filtered to reveal younger stars. For anther 10 hours, light was filtered to reveal older stars. These 10-hour images were merged to create the 20-hour final image.
The northwest plume was seen in the 1970s, but the technology provided limited detail. The astronomers found it's dominated by older, redder stars and has little gas, found in small patches. Due to the age of the stars and the extreme length of the plume, they suggest the plume was created by the interaction of an outer disk of M51 with another galaxy 200 million years ago or more.
The southern plume is an oddity. It has no morphological similarities with the surrounding parts of M51 and no gas. The plume has comparatively few stars and, therefore, mass, and little total light. One possibility, the researchers suggest, is the plume could be the remnants of a third satellite or body in the M51 system.
The northeast plume has about the same total light as the southern one. It may be an extension of the north side of the galaxy, but that is impossible to tell, Watkins said.
Other researchers discovered the southeastern gas tail in 1990 and assumed it was pulled out during an interaction with another galaxy. This new, deeper view still found no stars. That's unusual for such a tail, but it provides a clear test for future interaction models.
The astronomers are now devising other ways to look at M51, particularly to gather more detail from the faint plumes. The northwest plume is bright enough that it may be a good candidate for further study using the Hubble telescope, Watkins said.

Story Source:
The above story is based on materials provided by Case Western Reserve University. Note: Materials may be edited for content and length.

Journal Reference:

Aaron E. Watkins, J. Christopher Mihos, Paul Harding. DEEP IMAGING OF M51: A NEW VIEW OF THE WHIRLPOOL’S EXTENDED TIDAL DEBRIS. The Astrophysical Journal, 2015; 800 (1): L3 DOI: 10.1088/2041-8205/800/1/L3

Mining the Moon becomes a serious prospect

With an estimated 1.6 billion tonnes of water ice at its poles and an abundance of rare-earth elements hidden below its surface, the Moon is rich ground for mining.

In this month's issue of Physics World, science writer Richard Corfield explains how private firms and space agencies are dreaming of tapping into these lucrative resources and turning the Moon's grey, barren landscape into a money-making conveyer belt.
Since NASA disbanded its manned Apollo missions to the Moon over 40 years ago, unmanned spaceflight has made giant strides and has identified a bountiful supply of water ice at the north and south poles of the Moon.
"It is this, more than anything else," Cornfield writes, "that has kindled interest in mining the Moon, for where there is ice, there is fuel."
Texas-based Shackleton Energy Company (SEC) plans to mine the vast reserves of water ice and convert it into rocket propellant in the form of hydrogen and oxygen, which would then be sold to space partners in low Earth orbit.
As the company's chief executive officer, Dale Tietz, explains, the plan is to build a "gas station in space" in which rocket propellant will be sold at prices significantly lower than the cost of sending fuel from Earth.
SEC plans to extract the water ice by sending humans and robots to mine the lunar poles, and then use some of the converted products to power mining hoppers, lunar rovers and life support for its own activities.
Moon Express, another privately funded lunar-resources company, is also interested in using water ice as fuel -- but in a different form. It plans to fuel its operations and spacecraft using "high-test peroxide" (HTP), which has a long and illustrious history as a propellant.
As for mining the rare-earth elements on the Moon, China is making the most noticeable headway. The Jade Rabbit lander successfully touched down on the Moon in December 2013 and the Chinese space agency has publicly suggested establishing a "base on the Moon as we did in the South Pole and the North Pole."
With a near-monopoly on the dwindling terrestrial rare-earth elements, which are vital for everything from mobile phones to computers and car batteries, it is no surprise that China may want to cast its net wider.
"All interested parties agree that the Moon -- one step from Earth -- is the essential first toehold for humankind's diaspora to the stars," Corfield concludes.

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The above story is based on materials provided by Institute of Physics. Note: Materials may be edited for content and length.

'Live fast, die young' galaxies lose the gas that keeps them alive

This is an image showing galaxy J0836, the approximate location of the black hole residing at the galaxy's core, and the expelled gas reservoir

Galaxies can die early because the gas they need to make new stars is suddenly ejected, research published today suggests.

Most galaxies age slowly as they run out of raw materials needed for growth over billions of years. But a pilot study looking at galaxies that die young has found some might shoot out this gas early on, causing them to redden and kick the bucket prematurely.
Astrophysicist Ivy Wong, from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said there are two main types of galaxies; 'blue' galaxies that are still actively making new stars and 'red' galaxies that have stopped growing.
Most galaxies transition from blue to 'red and dead' slowly after two billion years or more, but some transition suddenly after less than a billion years--young in cosmic terms.
Dr Wong and her colleagues looked for the first time at four galaxies on the cusp of their star formation shutting down, each at a different stage in the transition.
The researchers found that the galaxies approaching the end of their star formation phase had expelled most of their gas.
Dr Wong said it was initially hard to get time on telescopes to do the research because other astronomers did not believe the dying galaxies would have any gas left to see.
The exciting result means the scientists will be able to use powerful telescopes to conduct a larger survey and discover the cause of this sudden shutdown in star formation.
Dr Wong said it is unclear why the gas was being expelled. "One possibility is that it could be blown out by the galaxy's supermassive black hole," she said.
"Another possibility is that the gas could be ripped out by a neighbouring galaxy, although the galaxies in the pilot project are all isolated and don't appear to have others nearby."
Swiss Federal Institute of Technology Professor Kevin Schawinski said the researchers predicted that the galaxies had to rapidly lose their gas to explain their fast deaths.
"We selected four galaxies right at the time where this gas ejection should be occurring," he said. "It was amazing to see that this is exactly what happens!"
The study appeared in the journal Monthly Notices of the Royal Astronomical Society, published by Oxford University Press.

Story Source:
The above story is based on materials provided by International Centre for Radio Astronomy Research. Note: Materials may be edited for content and length.

Journal Reference:

O. I. Wong, K. Schawinski, G. I. G. Jozsa, C. M. Urry, C. J. Lintott, B. D. Simmons, S. Kaviraj, K. L. Masters. Misalignment between cold gas and stellar components in early-type galaxies. Monthly Notices of the Royal Astronomical Society, 2015; 447 (4): 3311 DOI: 10.1093/mnras/stu2724

First stars were born much later than thought

Polarisation of the cosmic microwave background.

New maps from ESA's Planck satellite uncover the 'polarised' light from the early Universe across the entire sky, revealing that the first stars formed much later than previously thought.

The history of our Universe is a 13.8 billion-year tale that scientists endeavour to read by studying the planets, asteroids, comets and other objects in our Solar System, and gathering light emitted by distant stars, galaxies and the matter spread between them.
A major source of information used to piece together this story is the Cosmic Microwave Background, or CMB, the fossil light resulting from a time when the Universe was hot and dense, only 380,000 years after the Big Bang.
Thanks to the expansion of the Universe, we see this light today covering the whole sky at microwave wavelengths.
Between 2009 and 2013, Planck surveyed the sky to study this ancient light in unprecedented detail. Tiny differences in the background's temperature trace regions of slightly different density in the early cosmos, representing the seeds of all future structure, the stars and galaxies of today.
Scientists from the Planck collaboration have published the results from the analysis of these data in a large number of scientific papers over the past two years, confirming the standard cosmological picture of our Universe with ever greater accuracy.
"But there is more: the CMB carries additional clues about our cosmic history that are encoded in its 'polarisation'," explains Jan Tauber, ESA's Planck project scientist.
"Planck has measured this signal for the first time at high resolution over the entire sky, producing the unique maps released today."
Light is polarised when it vibrates in a preferred direction, something that may arise as a result of photons -- the particles of light -- bouncing off other particles. This is exactly what happened when the CMB originated in the early Universe.
Initially, photons were trapped in a hot, dense soup of particles that, by the time the Universe was a few seconds old, consisted mainly of electrons, protons and neutrinos. Owing to the high density, electrons and photons collided with one another so frequently that light could not travel any significant distant before bumping into another electron, making the early Universe extremely 'foggy'.
Slowly but surely, as the cosmos expanded and cooled, photons and the other particles grew farther apart, and collisions became less frequent.
This had two consequences: electrons and protons could finally combine and form neutral atoms without them being torn apart again by an incoming photon, and photons had enough room to travel, being no longer trapped in the cosmic fog.
Once freed from the fog, the light was set on its cosmic journey that would take it all the way to the present day, where telescopes like Planck detect it as the CMB. But the light also retains a memory of its last encounter with the electrons, captured in its polarisation.
"The polarisation of the CMB also shows minuscule fluctuations from one place to another across the sky: like the temperature fluctuations, these reflect the state of the cosmos at the time when light and matter parted company," says François Bouchet of the Institut d'Astrophysique de Paris, France.
"This provides a powerful tool to estimate in a new and independent way parameters such as the age of the Universe, its rate of expansion and its essential composition of normal matter, dark matter and dark energy."
Planck's polarisation data confirm the details of the standard cosmological picture determined from its measurement of the CMB temperature fluctuations, but add an important new answer to a fundamental question: when were the first stars born?
"After the CMB was released, the Universe was still very different from the one we live in today, and it took a long time until the first stars were able to form," explains Marco Bersanelli of Università degli Studi di Milano, Italy.
"Planck's observations of the CMB polarisation now tell us that these 'Dark Ages' ended some 550 million years after the Big Bang -- more than 100 million years later than previously thought.
"While these 100 million years may seem negligible compared to the Universe's age of almost 14 billion years, they make a significant difference when it comes to the formation of the first stars."
The Dark Ages ended as the first stars began to shine. And as their light interacted with gas in the Universe, more and more of the atoms were turned back into their constituent particles: electrons and protons.
This key phase in the history of the cosmos is known as the 'epoch of reionisation'.
The newly liberated electrons were once again able to collide with the light from the CMB, albeit much less frequently now that the Universe had significantly expanded. Nevertheless, just as they had 380 000 years after the Big Bang, these encounters between electrons and photons left a tell-tale imprint on the polarisation of the CMB.
"From our measurements of the most distant galaxies and quasars, we know that the process of reionisation was complete by the time that the Universe was about 900 million years old," says George Efstathiou of the University of Cambridge, UK.
"But, at the moment, it is only with the CMB data that we can learn when this process began."
Planck's new results are critical, because previous studies of the CMB polarisation seemed to point towards an earlier dawn of the first stars, placing the beginning of reionisation about 450 million years after the Big Bang.
This posed a problem. Very deep images of the sky from the NASA-ESA Hubble Space Telescope have provided a census of the earliest known galaxies in the Universe, which started forming perhaps 300-400 million years after the Big Bang.
However, these would not have been powerful enough to succeed at ending the Dark Ages within 450 million years.
"In that case, we would have needed additional, more exotic sources of energy to explain the history of reionisation," says Professor Efstathiou.
The new evidence from Planck significantly reduces the problem, indicating that reionisation started later than previously believed, and that the earliest stars and galaxies alone might have been enough to drive it.
This later end of the Dark Ages also implies that it might be easier to detect the very first generation of galaxies with the next generation of observatories, including the James Webb Space Telescope.
But the first stars are definitely not the limit. With the new Planck data released today, scientists are also studying the polarisation of foreground emission from gas and dust in the Milky Way to analyse the structure of the Galactic magnetic field.
The data have also enabled new important insights into the early cosmos and its components, including the intriguing dark matter and the elusive neutrinos, as described in papers also released today.
The Planck data have delved into the even earlier history of the cosmos, all the way to inflation -- the brief era of accelerated expansion that the Universe underwent when it was a tiny fraction of a second old. As the ultimate probe of this epoch, astronomers are looking for a signature of gravitational waves triggered by inflation and later imprinted on the polarisation of the CMB.
No direct detection of this signal has yet been achieved, as reported last week. However, when combining the newest all-sky Planck data with those latest results, the limits on the amount of primordial gravitational waves are pushed even further down to achieve the best upper limits yet.
"These are only a few highlights from the scrutiny of Planck's observations of the CMB polarisation, which is revealing the sky and the Universe in a brand new way," says Jan Tauber.
"This is an incredibly rich data set and the harvest of discoveries has just begun."
Series of publications: http://www.cosmos.esa.int/web/planck/publications

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The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.

15-million-year-old mollusk protein found

A team of Carnegie scientists have found "beautifully preserved" 15 million-year-old thin protein sheets in fossil shells from southern Maryland. Their findings are published in the inaugural issue of Geochemical Perspectives Letters.

The team--John Nance, John Armstrong, George Cody, Marilyn Fogel, and Robert Hazen--collected samples from Calvert Cliffs, along the shoreline of the Chesapeake Bay, a popular fossil collecting area. They found fossilized shells of a snail-like mollusk called Ecphora that lived in the mid-Miocene era--between 8 and 18 million years ago.
Ecphora is known for an unusual reddish-brown shell color, making it one of the most distinctive North American mollusks of its era. This coloration is preserved in fossilized remains, unlike the fossilized shells of many other fossilized mollusks from the Calvert Cliffs region, which have turned chalky white over the millions of years since they housed living creatures.
Shells are made from crystalline compounds of calcium carbonate interleaved with an organic matrix of proteins and sugars proteins and sugars. These proteins are called shell-binding proteins by scientists, because they help hold the components of the shell together.They also contain pigments, such as those responsible for the reddish-brown appearance of the Ecphora shell. These pigments can bind to proteins to form a pigment-protein complex.
The fact that the coloration of fossilized Ecphora shells is so well preserved suggested to the research team that shell proteins bound to these pigments in a complex might also be preserved. They were amazed to find that the shells, once dissolved in dilute acid, released intact thin sheets of shell proteins more than a centimeter across. Chemical analysis including spectroscopy and electron microscopy of these sheets revealed that they are indeed shell proteins that were preserved for up to 15 million years.
"These are some of the oldest and best-preserved examples of a protein ever observed in a fossil shell," Hazen said.
Remarkably, the proteins share characteristics with modern mollusk shell proteins. They both produce thin, flexible sheets of residue that's the same color as the original shell after being dissolved in acid. Of the 11 amino acids found in the resulting residue, aspartate and glutamate are prominent, which is typical of modern shell proteins. Further study of these proteins could be used for genetic analysis to trace the evolution of mollusks through the ages, as well as potentially to learn about the ecology of the Chesapeake Bay during the era in which Ecphora thrived.

Story Source:
The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.

Preventing greenhouse gas from entering the atmosphere

Microcapsule method offers new approach to carbon capture and storage at power plants. The new technique for carbon-capturing employs an abundant and environmentally benign sorbent: sodium carbonate, which is kitchen-grade baking soda. The microencapsulated carbon sorbents (MECS) achieve an order-of-magnitude increase in CO2 absorption rates compared to sorbents currently used. This illustration shows the flow-focusing microfluidic capillary device used to produce the silicone microcapsules

A team of researchers has developed a novel class of materials that enable a safer, cheaper, and more energy-efficient process for removing greenhouse gas from power-plant emissions. The approach could be an important advance in carbon capture and sequestration.

The team, led by scientists from Harvard University and Lawrence Livermore National Laboratory, employed a microfluidic assembly technique to produce microcapsules that contain liquid sorbents, or absorbing materials, encased in highly permeable polymer shells. They have significant performance advantages over the carbon-absorbing materials used in current capture and sequestration technology.
The work is described in a paper published online today in the journal Nature Communications.
"Microcapsules have been used in a variety of applications -- for example, in pharmaceuticals, food flavoring, cosmetics, and agriculture -- for controlled delivery and release, but this is one of the first demonstrations of this approach for controlled capture," said Jennifer A. Lewis, the Hansjörg Wyss Professor of Biologically Inspired Engineering at the Harvard School of Engineering and Applied Sciences (SEAS) and a co-lead author. Lewis is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering at Harvard.
Power plants are the single largest source of carbon dioxide (CO₂), a greenhouse gas that traps heat and makes the planet warmer. According to the U.S. Environmental Protection Agency, coal- and natural gas-fired plants were responsible for a third of U.S. greenhouse gas emissions in 2012.
That's why the agency has proposed rules mandating dramatically reduced carbon emissions at all new fossil fuel-fired power plants. Satisfying the new standards will require operators to equip plants with carbon-trapping technology.
Current carbon-capture technology uses caustic amine-based solvents to separate CO₂from the flue gas escaping a facility's smokestacks. But state-of-the-art processes are expensive, result in a significant reduction in a power plant's output, and yield toxic byproducts. The new technique employs an abundant and environmentally benign sorbent: sodium carbonate, which is kitchen-grade baking soda. The microencapsulated carbon sorbents (MECS) achieve an order-of-magnitude increase in CO₂absorption rates compared to sorbents currently used in carbon capture. Another advantage is that amines break down over time, while carbonates have a virtually limitless shelf life.
"MECS provide a new way to capture carbon with fewer environmental issues," said Roger D. Aines, leader of the fuel cycle innovations program at Lawrence Livermore National Laboratory and a co-lead author. "Capturing the world's carbon emissions is a huge job. We need technology that can be applied to many kinds of carbon dioxide sources, with the public's full confidence in the safety and sustainability."
Researchers at Lawrence Livermore and the U.S. Department of Energy's National Energy Technology Lab are now working on enhancements to the capture process to bring the technology to scale.
Aines says that the MECS-based approach could also be tailored to industrial processes like steel and cement production, which are significant greenhouse gas sources.
"These permeable silicone beads could be a 'sliced-bread' breakthrough for CO₂ capture -- efficient, easy-to-handle, minimal waste, and cheap to make," said Stuart Haszeldine, a professor of carbon capture and storage at the University of Edinburgh, who was not involved in the research. "Durable, safe, and secure capsules containing solvents tailored to diverse applications can place CO₂ capture … firmly onto the cost-reduction pathway."
MECS are produced using a double-capillary device in which the flow rates of three fluids -- a carbonate solution combined with a catalyst for enhanced CO₂absorption, a photo-curable silicone that forms the capsule shell, and an aqueous solution -- can be independently controlled.
"Encapsulation allows you to combine the advantages of solid-capture media and liquid-capture media in the same platform," said Lewis. "It is also quite flexible, in that both the core and shell chemistries can be independently modified and optimized."
"This innovative gas separation platform provides large surface areas while eliminating a number of operational issues, including corrosion, evaporative losses, and fouling," said Ah-Hyung (Alissa) Park, the chair in applied climate science and associate professor of Earth and environmental engineering at Columbia University, who was not involved in the research.
Lewis has previously conducted groundbreaking research in the 3-D printing of functional materials, including tissue constructs with embedded vasculature, lithium-ion microbatteries, and ultra-lightweight carbon-fiber epoxy materials.
Funding for the encapsulated liquid carbonates work was provided by the Innovative Materials and Processes for Advanced Carbon Capture Technology program of the U.S. Department of Energy's Advanced Research Projects Agency-Energy.

Story Source:
The above story is based on materials provided by Harvard University. The original article was written by Paul Karoff. Note: Materials may be edited for content and length.

Journal Reference:

John J. Vericella, Sarah E. Baker, Joshuah K. Stolaroff, Eric B. Duoss, James O. Hardin, James Lewicki, Elizabeth Glogowski, William C. Floyd, Carlos A. Valdez, William L. Smith, Joe H. Satcher, William L. Bourcier, Christopher M. Spadaccini, Jennifer A. Lewis, Roger D. Aines. Encapsulated liquid sorbents for carbon dioxide capture. Nature Communications, 2015; 6: 6124 DOI: 10.1038/ncomms7124

Wednesday, 4 February 2015

'Live fast, die young' galaxies lose the gas that keeps them alive

This is an image showing galaxy J0836, the approximate location of the black hole residing at the galaxy's core, and the expelled gas reservoir

Galaxies can die early because the gas they need to make new stars is suddenly ejected, research published today suggests.

Story Source:
The above story is based on materials provided by International Centre for Radio Astronomy Research. Note: Materials may be edited for content and length.

Journal Reference:

O. I. Wong, K. Schawinski, G. I. G. Jozsa, C. M. Urry, C. J. Lintott, B. D. Simmons, S. Kaviraj, K. L. Masters. Misalignment between cold gas and stellar components in early-type galaxies. Monthly Notices of the Royal Astronomical Society, 2015; 447 (4): 3311 DOI: 10.1093/mnras/stu2724