Aug 30, 2016

The rise and fall of galaxy formation

A comparison of visualizing galaxies with and without ZFOURGE.
An international team of astronomers, including Carnegie's Eric Persson, has charted the rise and fall of galaxies over 90 percent of cosmic history. Their work, which includes some of the most sensitive astronomical measurements made to date, is being published in The Astrophysical Journal.

The FourStar Galaxy Evolution Survey (ZFOURGE) has built a multicolored photo album of galaxies as they grow from their faint beginnings into mature and majestic giants. They did so by measuring distances and brightnesses for more than 70,000 galaxies spanning more than 12 billion years of cosmic time, revealing the breadth of galactic diversity.

The team assembled the colorful photo album by using a new set of filters that are sensitive to infrared light and taking images with them with the FourStar camera at Carnegie's 6.5-meter Baade Telescope at our Las Campanas Observatory in Chile. They took the images over a period of 45 nights. The team made a 3-D map by collecting light from over 70,000 galaxies, peering all the way into the distant universe, and by using this light to measure how far these galaxies are from our own Milky Way.

The deep 3-D map also revealed young galaxies that existed as early as 12.5 billion years ago (at less than 10 percent of the current universe age), only a handful of which had previously been found. This should help astronomers better understand the universe's earliest days.

"Perhaps the most surprising result is that galaxies in the young universe appear as diverse as they are today," when the universe is older and much more evolved, said lead author Caroline Straatman, a recent graduate of Leiden University. "The fact that we see young galaxies in the distant universe that have already shut down star formation is remarkable."

But it's not just about distant galaxies; the information gathered by ZFOURGE is also giving the scientists the best-yet view of what our own galaxy was like in its youth.

"Ten billion years ago, galaxies like our Milky Way were much smaller, but they were forming stars 30 times faster than they are today," said Casey Papovich of Texas A&M University.

"ZFOURGE is providing us with a highly complete and reliable census of the evolving galaxy population, and is already helping us to address questions like: How did galaxies grow with time? When did they form their stars and develop into the spectacular structures that we see in the present-day universe?" added Ryan Quadri, also of Texas A&M.

In the study's first images, the team found one of the earliest examples of a galaxy cluster, a so-called "galaxy city" made up of a dense concentration of galaxies, which formed when the universe was only three billion years old, as compared to the nearly 14 billion years it is today.

Read more at Science Daily

Traces of Prehistoric Baked Salmon Found

Salmon has been on the American menu for 11,800 years, says a new chemical investigation of prehistoric hearths.

Researchers from the University of Alaska Fairbanks (UAF) made the discovery as they excavated a total of 17 hearths from different time periods at the Upward Sun River site near the Tanana River in central Alaska.

To identify the fish remains, a team led by UAF postdoctoral researcher Kyungcheol Choy employed the same technique used to reconstruct ancient diets from cooking pottery and food residues. In this case, they analyzed the chemistry of sediments from each hearth.

"Most of archaeologists are interested in bone remains, human bones and pottery residues to reconstruct the food consumption in ancient people. However, fishbone remains are not preserved well and it's difficult to detect fish consumption in pre-pottery people," Choy told Discovery News.

The researchers examined chemical profiling of the hearth residues by carrying out stable isotope analysis and lipid residue analysis. In this way, they determined whether the food cooked there came from land animals and plants or aquatic ones.

"We confirmed the Upward Sun River site was used for cooking salmon and freshwater fish even though the site is located in the central Alaska," Choy said.

High nitrogen values in hearths indicated that fish was cooked in hearths dating to 11,800 and 11,500 years ago.

More in detail, the carbon ratios from lipids in hearths pointed to both marine and freshwater fish. Given the site location in central Alaska, far away from the ocean, the researchers concluded the marine species must have been salmon, which migrate from the ocean into rivers each year to spawn on gravel beds.

"DNA analysis of chum salmon bones from the same site on the Tanana River had previously confirmed that fish were part of the local indigenous diet as far back as 11,500 years ago," UAF said in a statement.

Read more at Discovery News

Mystery of Mars' Crater Chains Solved

Grooves on Mars' moon Phobos are likely caused by tidal forces – the mutual gravitational pull of the planet and the moon. But some of Phobos' crater chains don't line up.
Scientists have resolved a long-standing mystery of oddly aligned chains of craters on the Martian moon Phobos.

A new study shows that the peculiar chains of craters likely were created by material that had been boosted into space by a previous impact. After some time in orbit, the material crashed back into Phobos, forming chains of craters that are not aligned with surface features caused by the moon's deadly gravitational embrace with Mars.

Phobos, a small, potato-shaped moon of Mars, is covered with bulges and parallel linear features that are mostly aligned with tidal stresses as Phobos spirals closer to Mars, planetary scientists Michael Nayak and Erik Asphaug, with the University of California at Santa Cruz, write in a paper published in this week's Nature Communications.

"As the tidal bulge grows, surface stresses increase and cause striations. However, many of Phobos' linear features do not align with any interpretation of tidal stress, giving rise to alternative models," the scientists said.

They modeled the flight paths of material ejected into orbit by a primary impact strike and found that it left a chain of craters on Phobos as the process repeated.

The model was a match to one chain of craters on Phobos that had been unexplained by previous models.

Nayak and Asphaug conclude that these types of impacts likely created some of Phobos' crater chains, but that the massive tidal forces acting on Phobos also play a large role in shaping its surface features.

The scientists also noted that the lack of a crater chain near Stickney, Phobos' largest impact basin, suggests it formed when the moon was farther away from Mars.

From Discovery News

'Interesting' SETI Signal Detected: Noise or... Aliens?

The RATAN-600 radio telescope in Zelenchukskaya, Russia.
First things first, it's probably not aliens.

But astronomers have identified an "interesting" signal emanating from a not-so-distant sun-like star and the mere fact that I've mentioned aliens will have you thinking about aliens and not the other things this signal could be. I'm not saying it's aliens, OK? I really shouldn't have mentioned aliens.

Anyhow, let's wind this back a bit without mentioning ET. What's actually been detected?

Astronomers using the Russian RATAN-600 radio telescope have recorded "a strong signal in the direction of HD164595," according to Centauri Dreams' Paul Gilster who has access to a document that is currently circulating behind the scenes. The research is not published yet, but according to Gilster, the signal will be discussed during a SETI meeting at the 67th International Astronautical Congress (IAC) in Guadalajara, Mexico, in September.

The signal in question appears to be a radio burst with a frequency of 11 GHz that was detected by the observatory on May 15, 2015, coming from HD164595, which is located 95 light-years away and is known to possess one exoplanet. This exoplanet is likely "Neptune-like," approximately 4% the mass of Jupiter, with a 40 day orbit. Though this planet is very un-habitable for life as we know it (as it's very close to its star), there could be other undiscovered planets in the system.

But the interesting thing is that HD164595 is very sun-like, only a little older. The 6.3 billion year-old star is 99% the size of the sun and contains an almost identical chemical makeup. When looking for habitable worlds, it helps to find a star that has similar qualities to our sun as it's the only star known to have a planet orbiting that's packed with life.

So it becomes really interesting when a signal with few natural explanations is detected and, according to astronomer Nick Suntzeff of Texas A&M University in an interview with Ars Technica, a radio signal at this frequency is, well, "strange."

"If this were a real astronomical source, it would be rather strange," said Suntzeff, adding that his guess would be that the signal is actually terrestrial and may be a 11 GHz burst from a military source. However, there's no known program that would be using such a frequency.

The upshot is that little is so far known about this event and we'll have to wait until SETI astronomers can deduce what may have caused it. But for now, an intelligent extraterrestrial civilization blasting radio transmissions into space is a very slight possibility... though the thought is intriguing.

Gilster points out that for this to be a SETI signal, the hypothetical civilization would need to be a "Kardashev Type II civilization" if it's blasting radio in all directions (an omnidirectional radio beacon) to get cosmic attention. But if they were aiming a narrow beam signal directly at Earth, which requires far less energy, they could be a Type I civilization. As a comparison, a Type I civilization has evolved with the technological ability to harness all the energy that reached their planet from their star; a Type II civilization is much more advanced, with the ability of harnessing all of the energy from their star. In the latter case, this could be achieved using a Dyson sphere or swarm.

Read more at Discovery News

Aug 29, 2016

Strange New Objects Found During Hunt for 'Planet 9'

Astronomers have captured some interesting prey as they scan the distant solar systems for signs of a potential ninth major planet beyond Neptune.

Among the discoveries: the first Oort Cloud object that orbits entirely past Neptune. At the most distant part of its orbit, the newly found object, known as 2014 FE72, is 3,000 times farther away from the sun than Earth.

At that distance, FE72 is "likely being influenced by forces of gravity from beyond our solar system, such as other stars and the galactic tide," the Carnegie Institute for Science wrote in a press release.

Also submitted to the Minor Planet Center for official designations are the newly discovered extremely distant objects 2014 SR349 and 2013 FT28. Both so-called "trans-Neptunian objects" show signs their orbits may be under the gravitational influence of one or more large, undiscovered planets in the distant reaches of the solar system.

"The smaller objects can lead us to the much bigger planet we think exists out there," astronomer Scott Sheppard, with the Carnegie Institute for Science in Washington DC, said in a statement.

"The more we discover, the better we will be able to understand what is going on in the outer solar system," he added.

In 2014 Sheppard and colleague Chadwick Trujillo, with Northern Arizona University, discovered several extreme trans-Neptunian objects with similar orbital angles, raising the prospect that the bodies are being gravitationally influenced by an undiscovered, ninth planet more than 200 times farther away from the sun than Earth.

Calculations show the mystery planet would be at least several times bigger than Earth, and possibly as big as Neptune, which is about 17 times more massive than Earth.

So far, Sheppard and colleagues have scoured about 10 percent of the sky looking for objects beyond Neptune and the Kuiper Belt using the 6.5-meter Magellan Telescopes in Chile, NOAO's 4-meter Blanco telescope in Chile and the 8-meter Subaru telescope in Hawaii, among others.

Read more at Discovery News

'Cyclops' Beetle Grows Third Eye on Its Head

Onthophagus beetles are shown with the orthodenticle gene (left) and without it (right).
Baby beetles with three compound eyes, one in the center of their heads, are teaching scientists something about how new facial traits evolve.

The researchers focused on a group of dung beetles with horns in the genus Onthophagus. They were surprised to find that when they inactivated a certain gene, the beetle larvae developed into adults with no head horns. Instead, another compound eye popped up in an odd place.

"We were amazed that shutting down a gene could not only turn off development of horns and major regions of the head, but also turn on the development of very complex structures such as compound eyes in a new location," study leader Eduardo Zattara, a postdoctoral researcher at Indiana University's Department of Biology, said in a statement.

Like other insects, beetles hatch as larvae that then grow and metamorphose into adults. Based on research in flour beetles in the Tribolium genus, Zattara and his colleagues knew that certain genes are key to making the heads of the beetle larvae. But whether these same genes played any role in shaping adult heads was a mystery.

To find out, they figured out which parts of the larval heads turned into different parts of the adult head and then turned off some of those genes. (That research was a separate study led by Indiana University's Hannah Busey.) They found the intriguing "extra eye" results when they knocked out the so-called orthodenticle gene. Without that gene, most animal embryos don't develop a head or brain, the researchers noted.

Though beetle embryos also need orthodenticle to develop heads, nobody knew how the gene functioned in beetle larvae or adults. Turns out, during metamorphosis, the gene reorganizes the head and integrates the beetles' horns.

Shutting off orthodenticle in flour beetles did not have the same effect — they didn't grow extra eyes or lose their horns — suggesting the gene acquired this new function only in the heads of horned beetles, the researchers noted.

"Here we have a situation where a gene is already in the right place — the head — just not at the right time — the embryo instead of the adult," study researcher Armin Moczek, a biology professor at Indiana University, said in the statement. "By allowing the gene's availability to linger into later stages of development, it becomes easier to envision how it could then be eventually captured by evolution and used for a new function, such as the positioning of horns."

From Discovery News

Ancestor, Lucy, Died After Falling From Tree

Shown is a recreation of Australopithecus afarensis.
"Lucy," the iconic 3.18-million-year-old early human, literally dropped dead, according to new research that determined she died of injuries sustained after falling from a tall tree.

Since Lucy's species Australopithecus afarensis existed within a transitional period when our primate ancestors evolved from a more tree-dwelling lifestyle to a terrestrial one, the new findings -- published in the journal Nature -- indicate that adaptations that made it easier for our ancestors to walk on two legs on land compromised their ability to climb trees safely and efficiently. This may have predisposed them to falls from heights, as what may have happened to unfortunate Lucy, whose broken fossilized bones tell nearly the whole story.

"Today these fractures are often seen in automobile accidents, but also an impact following a fall from height," lead author John Kappelman, a professor of anthropology at The University of Texas at Austin, told Discovery News. "Since there were no cars in Lucy's time, we suggest that a fall is the mostly likely way that this subset of fractures formed, just as seen in modern patients today under natural conditions."

In order to assess Lucy's cause of death, Kappelman and his team studied her remains, which include parts of her skull, hand, axial skeleton, pelvis and foot. The scientists used computed tomographic scans to analyze these parts in detail, and then compared the findings to various documented clinical cases where the cause of death is clearly noted.

In addition to discovering that Lucy's cause of death is consistent with a fall from a high place -- presumed to have been from a tall tree due to where her remains were found in the Afar region of Ethiopia -- the fossil clues presented another key piece of evidence.

Fractures in Lucy's upper arms suggest that she stretched out her arms in an attempt to break her fall. This tells us that she was very much alive when she toppled to her demise, and did not die of a heart attack or from some other cause beforehand.

Lucy's distal radius (forearm bone) undergoes computed tomographic scanning.
The scientists further found that Lucy died relatively young, but was not a child, since she had all of her adult teeth, including a third molar -- a wisdom tooth.

"Her species appears to have grown up faster than us, probably more like a chimpanzee, and I suspect she was maybe 15 years old, so a young adult for her kind," Kappelman said.

Chimpanzees and other modern arboreal primates are far more agile at tree climbing than humans are. They can climb trees from a young age since it's a life or death matter for them.

But even chimps can fall to their death from trees. Famed primatologist Jane Goodall and her team documented 51 such falls in a two-year period, with breaking branches being one of the main reasons that they topple.

Lucy's feet had evolved for better walking on the ground, according to earlier research. This would have compromised her ability to clutch onto tree limbs, probably making falls more common.

Reconstruction of the foot of Lucy's species, Australopithecus afarensis, with one of the more recently found bones highlighted.
Kappelman, however, does not think that this risk caused our primate ancestors to become fully terrestrial.

He said that the arboreal lifestyle "is still a viable niche for lots of animals, including the majority of primates. The first committed terrestrial bipeds (two-legged ground walkers) are probably Homo erectus, but even some modern humans forage in the trees."

He and his colleagues suspect that small-bodied Lucy nested in trees at night to avoid predators, which is what chimps and gorillas do today. This means that, "at a minimum, she climbed up a tree at night, slept there for some hours, and climbed down from that tree in the morning," Kappelman said, adding that she might have sometimes foraged for food in trees too.

Experts contacted by Discovery News were all intrigued by the new study.

Osbjorn Pearson, an associate professor in the University of New Mexico's Department of Anthropology, said, "The evidence was literally right under the noses of many anthropologists for the last three and a half decades," referring to the time since 1982 that researchers have known of Lucy's remains.

Read more at Discovery News

Frogs Find Mates with Ultrasonic Calls in Noisy Streams

The frog Huia cavitympanum, from the island of Borneo, has evolved calls to be heard over the noise of rushing water.
Some frogs have evolved ultrasonic mating calls so they can be heard above the background rumble of the fast-flowing streams they depend on, say researchers.

Biologist Dr Sandra Goutte of Sorbonne University in Paris and her and colleagues studied the calls of a group of "torrent frogs" in Borneo, Indonesia, Malaysia, China and Cambodia.

They discovered the frogs all had higher pitched calls than most other frogs in the world, and a few species even had ultrasonic calls.

"You can see the frog calling but you cannot hear it," said Dr Goutte, who carried out the research for her PhD research.

"The call of torrent frogs has most probably been constrained by the environment they live in — which is the torrents — that are really noisy."

Male torrent frogs generally put out mating calls while sitting in vegetation next to fast-flowing streams. Females lay their eggs on rocks and then the tadpoles thrive in the oxygen-rich waters nearby.

The problem is falling water makes a low pitched rumble of about 2 kilohertz that would mask the pitch of most frog mating calls, which are generally under 5 kilohertz.

Dr Goutte and colleagues measured the call pitch of 70 species of torrent frogs, that range in size from 2 to 15 centimeters in body length.

They found that, on average, most of the frogs had calls that ranged between 4 and 10 kilohertz.

A few species had calls that consisted of frequency above 20 kilohertz, which is in the ultrasonic range, above the human range of hearing.

For example, the hole-in-the-head frog (Huia cavitympanum), which is found in Borneo, has purely ultrasonic calls.

"As a result we don't hear anything, but the frogs do," said Dr Goutte.

While the large odorous frog (Odorrana graminea), a species found in China, had partially ultrasonic calls.

"We hear only a part of the call," said Dr Goutte.

Read more at Discovery News

Dark Streaks on Mars Hold Water, But Not Much

The dark streaks are called recurring slope lineae (RSL), and last year, scientists presented new evidence suggesting that these streaks contain liquid water — albeit very, very salty water called brine. The new work shows that these RSL cannot contain more water than the driest deserts on Earth, which makes it unlikely that water is streaming down these hillsides.

In an attempt to determine the water content of the RSL, researchers turned to Mars Odyssey's Thermal Emission Imaging System (THEMIS), and looked at the temperature of the planet's surface from orbit.

"When water is present in the spaces between particles of soil or grains of sand, it affects how quickly a patch of ground heats up during the day and cools off at night," NASA officials said in a statement. The depth to which the water saturates the soil also influences how quickly the surface changes temperature, according to NASA.

The researchers studied the RSL on the walls of craters within the Valles Marineris canyon on Mars. They looked at several years' worth of surface-temperature measurements by THEMIS, to figure out the water concentration in the soil.

The researchers found that the upper limit of the water content was about 3 percent by weight — about the same concentration of water as in the surface material of the Atacama Desert in Chile and the Antarctic Dry Valleys, which are two of the driest places in the world.

The findings presented in 2015 showed evidence of "hydrated salts" (or brines) at the surface where the dark streaks are located.

"Our findings are consistent with the presence of hydrated salts, because you can have hydrated salt without having enough for the water to start filling pore spaces between particles," said Christopher Edwards, a faculty member in the Department of Physics and Astronomy at Northern Arizona University and one of the study's authors. "Salts can become hydrated by pulling water vapor from the atmosphere, with no need for an underground source of the water."

Read more at Discovery News

Aug 27, 2016

Memory activation before exposure reduces life-long fear of spiders

By disrupting the recreation of fear memories, exposure therapy can be made more effective for anxiety disorder patients, suggests a new report.
Many people suffer from anxiety and fears, and a common treatment for these problems is exposure therapy. In a new study published in Current Biology, researchers at Uppsala University have shown how the effect of exposure therapy can be improved by disrupting the recreation of fear-memories in people with arachnophobia.

Studies show that up to 30 per cent of all people suffer an anxiety disorder at some point in their lives. Anxiety leads to great suffering for those affected, but can be treated with exposure therapy, in which the patient is gradually exposed to the object or context that provokes the reactions. If exposure therapy is successful, a new 'safe' memory is formed, which overshadows the old fear memory. But not everyone is helped by this treatment, in part because the learning that takes place during the treatment is not permanent; the memory may return at some point later on after an initially successful exposure. Memory researchers have now demonstrated that the improvement can be made more lasting.

When a person is reminded of something, the memory becomes unstable and is re-saved. If you disrupt the re-saving of the memory, so-called reconsolidation, the creation of the memory can be disrupted and the memory that is saved can be changed. A fear memory could thus be weakened or erased, and this offers hope for improved treatment of anxiety disorders. But until now there has been doubt if this would be possible because older and stronger memories have proven to be difficult to disrupt.

In a study published in the journal Current Biology, researchers from Uppsala University and Karolinska Institutet in Sweden have now for the first time shown that it is possible to use this method to reduce fear in life-long phobias. The researchers exposed individuals with arachnophobia to spider pictures while measuring their brain activity in the amygdala, a part of the brain that is strongly linked to fear.

They found that an activation of the fear memory, consisting of a mini-exposure 10 minutes before a more extensive exposure, led to significantly reduced amygdala activity when the subjects looked at the spider pictures again the following day. Because the memory is made unstable before exposure and re-saved in its weakened form, the fear does not return as easily. The day after exposure, the group that received an initial activation of their spider fear showed reduced amygdala activity in comparison with a control group. Avoidance of spiders also decreased, which could be predicted from the degree of amygdala activation.

'It is striking that such a simple manipulation so clearly affects brain activity and behaviour. A simple modification of existing treatments could possibly improve effects. This would mean more people getting rid of their anxieties after treatment and fewer relapses,' says Johannes Björkstrand, PhD student at the Department of Psychology, Uppsala University.

From Science Daily