Jun 23, 2016

The universe: Learning about the future from the distant past

Our universe came to life nearly 14 billion years ago in the Big Bang -- a tremendously energetic fireball from which the cosmos has been expanding ever since. Today, space is filled with hundreds of billions of galaxies, including our solar system's own galactic home, the Milky Way. But how exactly did the infant universe develop into its current state, and what does it tell us about our future?

These are the fundamental questions "astrophysical archeologists" like Risa Wechsler want to answer. At the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) of Stanford and the Department of Energy's SLAC National Accelerator Laboratory, her team combines experimental data with theory in computer simulations that dig deeply into cosmic history and trace back how matter particles clumped together to form larger and larger structures in the expanding universe.

"Most of our calculations are done at KIPAC, and computing is a crucial aspect of the collaboration between SLAC and Stanford," says Wechsler, who is an associate professor of physics and of particle physics and astrophysics.

Wechsler's simulated journeys through spacetime use a variety of experimental data, including observations by the Dark Energy Survey (DES), which recently discovered a new set of ultra-faint companion galaxies of our Milky Way that are rich in what is known as dark matter. The gravitational pull from this invisible form of matter affects regular matter, which plays a crucial role in the formation and growth of galaxies.

Dark energy is another key ingredient shaping the universe: It inflates the universe like a balloon at an ever-increasing rate, but researchers don't know much about what causes the acceleration.

Two future projects will give Wechsler and other researchers new clues about the mysterious energy. The Dark Energy Spectroscopic Instrument (DESI), whose science collaboration she is leading, will begin in 2018 to turn two-dimensional images of surveys like DES into a three-dimensional map of the universe. The Large Synoptic Survey Telescope (LSST), whose ultrasensitive 3,200-megapixel digital eye is being assembled at SLAC, will start a few years later to explore space more deeply than any telescope before.

"Looking at faraway galaxies means looking into the past and allows us to measure how the growth and distribution of galaxies were affected by dark energy at different points in time," Wechsler says. "Over the past 10 years, we've made a lot of progress in refining our cosmological model, which describes many of the properties of today's universe very well. Yet, if future data caused this model to break down, it would completely change our view of the universe."

Read more at Science Daily

Possible solution to 'faint young Sun paradox'

In the first billion years of Earth's history, the planet was bombarded by primordial asteroids, while a faint Sun provided much less heat. A Southwest Research Institute-led team posits that this tumultuous beginning may have ultimately fostered life on Earth, particularly in terms of sustaining liquid water.

"The early impacts caused temporary, localized destruction and hostile conditions for life. But at the same time, they had a long-term beneficial effect in stabilizing surface temperatures and delivering key elements for life as we know it," said Dr. Simone Marchi, a senior research scientist at SwRI's Planetary Science Directorate in Boulder, Colo. He is the lead author of a paper, "Massive Impact-induced Release of Carbon and Sulfur Gases in the Early Earth's Atmosphere," recently published in the journal Earth and Planetary Science Letters. The paper addresses a major problem, one of the outstanding mysteries in the history of the solar system and Earth -- the faint young Sun paradox.

"Atmospheric and surface conditions during the first billion years of Earth's history are poorly understood due to the scarcity of geological and geochemical evidence," said Marchi. However, ancient zircon crystals in sedimentary rocks provide evidence that our planet had liquid oceans, at least intermittently, during this earliest period. His team created a new model for impact-generated outgassing on the early Earth, showing how a resulting greenhouse effect could have counterbalanced the weak light from the infant Sun enough to sustain liquid water.

The findings could be key to understanding how life started on Earth despite the faint young Sun and havoc caused by collisions. Studies of other stars, as well as theoretical modeling, have shown that Sun-like stars begin their life about 20 to 30 percent fainter in visible wavelengths than the Sun is at present. They gradually increase in luminosity over time.

"Today Earth is in the 'Goldilocks zone,' where liquid water can exist on its surface," said Marchi. Referencing the fairy tale about the three little bears, the Goldilocks zone is an orbit around a star where it's not too hot, nor too cold, for liquid water. Liquid water is generally considered a key ingredient for life. When the Sun was much fainter, the Earth with its present atmospheric composition would have been frozen solid. If the oceans were frozen, life may not have formed.

The most straightforward explanation would be a massive atmospheric greenhouse effect, from either carbon dioxide or methane, or both. Previous work has speculated that volcanic outgassing or impact-vaporized materials could have released greenhouse gases. Marchi's team proposes a novel, more efficient mechanism As the planet was pummeled by primordial asteroids -- some larger than 100 kilometers in diameter -- impacts would melt large volumes of rock, creating temporary lakes of lava. These pools of lava could have released large quantities of carbon dioxide to the atmosphere.

Read more at Science Daily

Scientists reveal single-neuron gene landscape of the human brain

A team of scientists at The Scripps Research Institute (TSRI), University of California, San Diego (UC San Diego) and Illumina, Inc., has completed the first large-scale assessment of single neuronal "transcriptomes." Their research reveals a surprising diversity in the molecules that human brain cells use in transcribing genetic information from DNA to RNA and producing proteins.

The researchers accomplished this feat by isolating and analyzing single-neuronal nuclei from the human brain, allowing classification of 16 neuronal subtypes in the brain's cerebral cortex, the "gray matter" involved in thought, cognition and many other functions.

"Through a wonderful scientific collaboration, we found an enormous amount of transcriptomic diversity from cell to cell that will be relevant to understanding the normal brain and its diseases such as Alzheimer's, Parkinson's, ALS and depression," said TSRI Professor and neuroscientist Jerold Chun, who co-led the study with bioengineers Kun Zhang and Wei Wang of UC San Diego and Jian-Bing Fan of Illumina.

The study was published on June 24 in the journal Science.

All the Same

While parts of the cerebral cortex look different under a microscope--with different cell shapes and densities that form cortical layers and larger regions having functional roles called "Brodmann Areas"--most researchers treat neurons as a fairly uniform group in their studies.

"From a tiny brain sample, researchers often make assumptions that obtained information is true for the entire brain," said Chun.

But the brain isn't like other organs, Chun explained. There's a growing understanding that individual brain cells are unique, and a possibility has been that the microscopic differences among cerebral cortical areas may also reflect unique transcriptomic differences--i.e., differences in the expressed genes, or messenger RNAs (mRNAs), which carry copies of the DNA code outside the nucleus and determine which proteins the cell makes.

To better understand this diversity, the researchers in the new study analyzed more than 3,200 single human neurons--more than 10-fold greater than prior publications--in six Brodmann Areas of one human cerebral cortex.

With the help of newly developed tools to isolate and sequence individual cell nuclei (where genetic material is housed in a cell), the researchers deciphered the minute quantities of mRNA within each nucleus, revealing that various combinations of the 16 subtypes tended to cluster in cortical layers and Brodmann Areas, helping explain why these regions look and function differently.

Neurons exhibited anticipated similarities, yet also many differences in their transcriptomic profiles, revealing single neurons with shared, as well as unique, characteristics that likely lead to differences in cellular function.

"Now we can actually point to an enormous amount of molecular heterogeneity in single neurons of the brain," said Gwendolyn E. Kaeser, a UC San Diego Biomedical Sciences Graduate Program student studying in Chun's lab at TSRI. Kaeser was co-first author of the study with Blue B. Lake and Rizi Ai of UC San Diego and Neeraj S. Salathia of Illumina.

Many New Questions

Interestingly, some of these differences in gene expression have roots in very early brain development taking place before birth. The researchers found markers on some neurons showing that they originated from a specific region of fetal brain called the ganglionic eminence, which generates inhibitory neurons destined for the cerebral cortex. These neurons may have particular relevance to developmental brain disorders.

The enormous transcriptomic diversity of single neurons was predicted by earlier work from Chun's laboratory and others showing that the genomes--the DNA--of individual brain cells can be different from cell to cell. In future studies, the researchers hope to investigate how single-neuron DNA and mRNA differs in single neurons, groups and between human brains--and how these may be influenced by factors such as stress, medications or disease.

Read more at Science Daily

SETI Eavesdrops on Nearby Star in Smart Alien Hunt

Astronomers seeking out extraterrestrial intelligence have used a powerful radio telescope to eavesdrop on a star system that is relatively close to Earth in the hope of hearing the faint radio whisper of an alien civilization.

Using the Allen Telescope Array (ATA) located in California (pictured top), members of the SETI Institute chose Trappist 1 as they know the red dwarf-type star plays host to at least 3 exoplanets. Traditional SETI searches have looked to random stars in the sky in the hope of detecting an artificial radio signal using luck and some educated guesses. But now we know certain stars play host to exoplanets, alien hunters can be a little more discerning with the selection of stellar targets.

Known as "targeted SETI", the ATA has been used to "listen in" on star systems that NASA's Kepler Space Telescope and other exoplanet-hunting missions have confirmed the presence of exoplanets. Even better than that, as Kepler can identify the physical size and orbit of a given exoplanet, astronomers can deduce whether that planet is located in the star's "habitable zone." The habitable zone around any star is the distance at which a hypothetical rocky planet can orbit that is not too hot or too cold for liquid water to exist. As we know from life on our planet, where there's water, there's life; could intelligent alien life be living on one of these potentially habitable worlds?

If so, they might be transmitting radio waves. However, for us to stand a chance of detecting their signals, they either need to be deliberately blasting a radio beacon in our direction with the explicit purpose of communication or they need to live in a relatively nearby star system for us to detect their accidental leakage of radio waves into space.

Earth has been leaking a faint radio signals into space for over 100 years since the advent of commercial radio transmissions around the globe at the beginning of the 20th century. More recently, we've been pinging asteroids and the planets with powerful radar. And let's not forget the controvercial Messaging Extraterrestrial Intelligence, or METI, a practice that has unsettled some scientists. Therefore, in theory, any intelligent aliens living within 100 light-years of Earth -- assuming they possess sensitive enough radio receivers -- could be aware of our presence.

And this is what SETI is doing: listening out for alien transmissions that, so far, have proven inconclusive.

However, last year, Kepler discovered a bizarre transit signal from the star KIC 8462852, otherwise known as Tabby's Star. Kepler detects exoplanets by detecting their faint shadows cross the faces of their host stars. When Kepler detected Tabby's Star transit, it was like nothing it had ever recorded; the brightness dip dimmed around 20 percent. Though the generally-accepted hypothesis is that a swarm of comets may have caused this strange transit signal, there's another idea that it could be evidence of an advanced alien civilization building a "megastructure" around their star.

Tabby's Star quickly became a target for SETI, but no transmissions were detected by the ATA.

According to a SETI Institute news release on Wednesday, even if there were transmitting aliens at Tabby's Star, the fact it's nearly 1,500 light-years away would make the detection of alien radio signals extremely unlikely, unless said aliens were deliberately beaming extremely powerful radio waves right at us.

This is why Trappist 1 was selected for a follow-up SETI investigation. Though there's no evidence of weird transit signals around this small star, it is an ancient compact planetary system that might, after some assumptions, be considered habitable. What's more, Trappist 1 is only 40 light-years away -- pretty much on our interstellar doorstep. Any signal transmitted from the Trappist 1 system would be a thousand times stronger than a signal of identical strength transmitted from Tabby's Star.

So, for 2 days in May, the ATA focused on Trappist 1, seeking out an artificial narrowband signal of around 1 Hz or less. As the headline of this article isn't "Aliens Found!" you can guess what the outcome was: no aliens were detected on this pass. But the ATA did put a valuable upper limit on the strength of a signal if there is a hypothetical alien civilization transmitting a signal at us.

Read more at Discovery News

Black Hole Crashes Warp Spacetime 1,000 Times Yearly

Crashes of black holes similar to the one that triggered the first detection of gravitational waves in September happen about 1,000 times per year and should be detectable with the next-generation of gravitational wave observatories, a new study shows.

The finding stems from an attempt to discover the source of the Sept. 14, 2015, black hole merger that set off vibrations in space and across time.

The detection of so-called gravitational waves, predicted 100 years ago by Albert Einstein, demonstrated a new technique for observing the universe.

In the new study, reported in this week's Nature, Warsaw University astrophysicist Krzysztof Belczynski and colleagues conclude that the pair of black holes, each about 30 times more massive than the sun, probably started off as two behemoth stars that formed about 2 billion years after the Big Bang.

The stars, which were estimated to be between 40 and 100 times more massive than the sun, didn't last long. About 5 million years after forming, they became black holes that orbited one another for another 10.3 billion years.

The pair then merged in crash so violent that it warped the interwoven fabric of space and time, setting off a wave, which 1.2 billion years later was detected by Laser Interferometer Gravitational-Wave Observatory, or LIGO, on Earth.

"The black holes were monsters, and the results show that their progenitor stars would have been some of the brightest and most massive in the universe," physicist J.J. Eldridge, with the University of Auckland in New Zealand, writes in a commentary in this week's Nature.

"If the proposed age of the stars' formation is correct, then they might have contributed to the re-ionization of the universe — one of the key events in the universe's evolution," Eldridge added.

The research is based on very precise numerical simulations of the formation of binary black holes from isolated pairs of binary stars, Belczynski and colleagues write.

The models serve as "a framework within which to interpret the first gravitational-wave source … and to predict the properties of subsequent binary-black-hole gravitational-wave events," the scientists said.

In addition to estimating the number of black hole mergers, the study has implications for understanding how stars evolve and die.

"Belczynski and colleagues' study is tremendously exciting," Eldridge said. "With each gravitational-wave signal detected we'll learn something new."

Read more at Discovery News

Jun 22, 2016

Wasp Species Seen for First Time in a Century

A wasp no one has documented since World War I has been spotted again.

What's more, underscoring nature's penchant for pin action, this wasp story is really a combined wasp, beetle and tree story.

First, the wasp.

Researchers from University of California, Riverside (UCR) and the U.S. Department of Agriculture (USDA) say they have rediscovered Oobius depressus, a wasp last studied from specimens found in Morristown, Ill. in 1914, samples that lacked key identifying features such as heads and antennae.

To find the mysteriously absent critter, the scientists set an insect trap in the canopy of a black locust tree in Michigan, and within a couple of months it produced a female specimen of the wasp.

Which brings us to the beetle.

Presence of the wasp is never good news for the wood-boring beetle Megacyllene robiniae. The wasp "parasitizes" the beetle's eggs, using them as depositories for its own eggs.

Indeed, the black wasp found by the researchers had a body "flat" enough to snoop around beneath tree bark in search of beetle eggs.

Meanwhile, the beetle, no angel itself, is a rampant pest of the black locust tree (Robinia pseudoacacia): Its larvae bore holes in the tree's bark that are big enough to invite wind-blown fungus spores that cause rot in the trunk and branches of the tree from its center.

Fewer beetles, then, would be good news for the tree. Black locust trees, though native to the southeastern United States, are planted widely across the globe in temperate areas. In the eastern United States, it's a key honey source. The tree grows fast and its wood is tough and durable and makes great lumber, but the beetle's damage can depress that use of the tree.

The Big However in all of this is that it's not yet clear how many of the lost wasp are out there. The researchers' chief goal was to re-establish the wasp and update its picture in the taxonomic photo album -- upgrading it to one with, for example, a head.

"We did it solely to redescribe the species taxonomically and make it recognizable, because the type specimens are incomplete and the original description was very poor and without illustrations," UCR entomologist and study co-author Serguei Triapitsyn told Discovery News in an email.

Read more at Discovery News

The Myth of the 'Fred Flintstone' Treatment

If someone comes down with a case of amnesia caused by traumatic head injury, what's the best way to bring him or her back to normal?

Any fan of The Flintstones knows the answer to that question: Simply bonk the amnesiac on the head again to realign the senses. It worked for Fred, after all, whenever a stray bowling ball found its way to his skull, as if drawn to him.

This course of action is also likely known to anyone in the medical profession as one the worst treatments imaginable for any head trauma. And yet, the idea that a second trauma could effectively offset the first to restore an amnesiac's memory is endorsed by upwards of 46 percent of the general public, finds Drexel University psychology professor Mary Spiers.

 So how is that anyone could ever consider this Stone Age treatment an effective remedy? Rather that tracing back to prehistory, the notion of a second knock on the noggin to cure amnesia has its roots in 19th-century medicine, Spiers writes in an article published in the journal Neurology.

The traumatic treatment was first theorized by French scientist named Francois Xavier Bichat. He reasoned that the two hemispheres of the brain acted in sync. As such, in order to restore balance, what happens on one side must be duplicated on the other.

His evidence for his supposed amnesia cure? None whatsoever.

"From my reading of Bichat's work, it seems that he felt that the second trauma amnesia cure was a common occurrence and didn't need the citation of an individual case," Spiers said. "This was not unusual at the time, to forgo evidence like that."

Before he could even be bothered to prove his case, Bichat died of what was likely a traumatic head injury in 1802. And yet Bichat's untested insights, known as Bichat's Law of Symmetry, were taken up by doctors, scientists and otherwise learned individuals of the time, published and passed on for decades after his death.

When scientists finally came around to the fact that you don't fight traumatic brain injury with traumatic brain injury, it was too late. Rather unlike the faded images in an amnesiac's mind, the memory stuck in the public consciousness.

Read more at Discovery News

Large-Scale Motion Detected Around San Andreas Fault

For the first-time, scientists have confirmed the existence of a previously-hypothesized form of movement in Earth's crust surrounding the San Andreas Fault system.

That the crust around the fault -- an 800-mile stretch of California where the Pacific and North American tectonic plates rub up against each other -- is capable of movement is hardly a revelation. Just check out photographs of San Francisco on April 18, 1906. Or ask The Rock. The northern part of the fault, which ruptured along 300 miles and killed between 700 and 2,800 people in 1906, experienced its most recent notable temblor in the form of the 1989 Loma Prieta quake, which struck during Game 3 of the World Series and, more seriously, injured more than 3,000 people and took the lives of 63.

The southern segment of the fault, however, has not experienced a major release of energy since 1857, and the most southerly portion of that southern segment hasn't suffered a major quake since 1690. It is the thought of so much seismic energy building up over the course of centuries that feeds anxieties about the prospect of the imminent arrival of "The Big One." Such anxieties are shared by some experts, too; in May, Thomas Jordan of the Southern California Earthquake Center observed that, "The springs on the San Andreas system have been wound very, very tight. And the southern San Andreas fault, in particular, looks like it's locked, loaded and ready to go."

Unfortunately, scientists are unable to predict earthquakes; furthermore, there is no consensus as to whether they ever will be able to. The best that researchers can do in the meantime is continue to gather as much information as they possibly can about the geology and seismology of fault lines; and several million San Franciscans and Los Angelenos are hanging anxiously on their every utterance. Hence the interest in a recent paper in the journal Nature Geoscience, which revealed a little bit more information about the way the earth is moving around the San Andreas Fault.

The fault is what's known as a strike slip, or transform, fault: the two plates are pushing horizontally against each other. But modelling of the plates' horizontal movements suggested that there should also be a small amount of ongoing vertical motion, as well. Such movements have been difficult to detect, but through careful analysis of data from GPS sensor arrays deployed around the fault, researchers from the University of Hawaii at Mānoa, University of Washington and Scripps Institution of Oceanography have now succeeded in doing so.

The movements are not large: around 2 millimeters a year. But they are spread out over a large area, in the form of 125-mile-wide "lobes" of uplift and subsidence. Notwithstanding some overly dramatic tabloid headlines, the new paper says nothing about the likelihood or likely scale of "The Big One." But it does add more knowledge and understanding of the way the crust around the fault moves and may help scientists calculate some of the likely impacts when and if The Big One eventually strikes.

From Discovery News

New Horizons Finds Clues of an Ocean on Pluto

Simulations of Pluto's geological evolution suggest more evidence that a liquid ocean may lie beneath the dwarf planet's surprisingly young surface.

There's long been speculation that there may be an ocean hiding below Pluto's frozen surface, but until now observational evidence has been inconclusive. However, as we continue to stare in awe at the ever-sharpening dwarf planet's complex landscape, some tantalizing clues as to what lies beneath are beginning to present themselves.

Probably the most profound discovery by NASA's New Horizons mission, which buzzed Pluto on July 14, 2015, is that the world has an active geology. This is a surprise; Pluto orbits the sun around 40 times times further away than the Earth orbits the sun. Shouldn't it be a barren, frozen wasteland? Apparently not. Pluto has complex geology, sporting a surprisingly young surface composed of a rich assortment of chemicals, including water, ammonia and methane ices.

The planet's apparent youth is caused by a complex interplay between the surface ice sublimating into the world's thin atmosphere (which, by the way, may even support clouds) and internal motions of ice that act like a lava lamp, slowly cycling chemicals from below.

This dynamic behavior seems odd and it could be a strong indicator that Pluto has an ocean -- albeit a very alien one. Now, in a paper published by the journal Geophysical Research Letters, planetary scientists have carried out numerical simulations of Pluto's geological evolution and their conclusions are fascinating.

"Thanks to the incredible data returned by New Horizons, we were able to observe tectonic features on Pluto's surface, update our thermal evolution model with new data and infer that Pluto most likely has a subsurface ocean today," said lead author and graduate student Noah Hammond, of Brown University, in a statement. "What New Horizons showed was that there are extensional tectonic features, which indicate that Pluto underwent a period of global expansion.

"A subsurface ocean that was slowly freezing over would cause this kind of expansion."

As water freezes, it expands -- a reason why you should never put a glass bottle of water in the freezer; it would shatter as the water freezes. As water ice expands, it also becomes buoyant (re: icebergs or the ice cubes floating in your G&T).

OK, so there's features that show Pluto has expanded, but who's to say that the dwarf planet did have a subsurface ocean, which has since frozen long ago? Well, after freezing, the frozen subsurface ocean would experience extreme pressure and increasingly cold conditions as Pluto's internal heat is radiated into space. What would then form is a phase of ice that we don't experience in everyday life here on Earth. Known as "ice II," this phase of water ice can only be produced in the laboratory, but is thought to exist in the icy moons of the outer solar system such as Jupiter's Ganymede. In this phase, water molecules form a crystalline structure that cause ice II's volume to contract and its density to increase. It is no longer buoyant.

Therefore, if Pluto's subsurface ocean froze long ago in the solar system's history, Hammond's simulations show that New Horizons should have seen ancient compression features during its flyby, such as the wrinkles and mare ridges found on the surface of Earth's moon -- features created by contraction after the moon cooled. In fact, the opposite is true; Pluto's landscape is filled with geological features that suggest expansion. This only adds to the hypothesis that Pluto's strikingly dynamic surface is a sign that there's a liquid water ocean below covered with a crust of ice.

"In our paper, we look at tectonic features on the surface of Pluto to understand the interior and we run thermal evolution models to help us understand how Pluto's interior may have evolved over time," said Hammond. "Our study further supports that hypothesis by showing that if the ocean froze, ice II would likely form, causing compressional tectonic features which are absent from the surface."

"Many people thought that Pluto would be geologically 'dead,' that it would be covered in craters and have an ancient surface," added coauthor Amy C. Barr, of the Planetary Science Institute (PSI). "Our work shows how even Pluto, at the edge of the solar system, with very little energy, can have tectonics."

Read more at Discovery News

Jun 21, 2016

'Space tsunami' causes the third Van Allen Belt

Earth's magnetosphere, the region of space dominated by Earth's magnetic field, protects our planet from the harsh battering of the solar wind. Like a protective shield, the magnetosphere absorbs and deflects plasma from the solar wind which originates from the Sun. When conditions are right, beautiful dancing auroral displays are generated. But when the solar wind is most violent, extreme space weather storms can create intense radiation in the Van Allen belts and drive electrical currents which can damage terrestrial electrical power grids. Earth could then be at risk for up to trillions of dollars of damage.

Announced today in Nature Physics, a new discovery led by researchers at the University of Alberta shows for the first time how the puzzling third Van Allen radiation belt is created by a "space tsunami." Intense so-called ultra-low frequency (ULF) plasma waves, which are excited on the scale of the whole magnetosphere, transport the outer part of the belt radiation harmlessly into interplanetary space and create the previously unexplained feature of the third belt.

"Remarkably, we observed huge plasma waves," says Ian Mann, physics professor at the University of Alberta, lead author on the study and former Canada Research Chair in Space Physics. "Rather like a space tsunami, they slosh the radiation belts around and very rapidly wash away the outer part of the belt, explaining the structure of the enigmatic third radiation belt."

The research also points to the importance of these waves for reducing the space radiation threat to satellites during other space storms as well. "Space radiation poses a threat to the operation of the satellite infrastructure upon which our twenty-first century technological society relies," adds Mann. "Understanding how such radiation is energized and lost is one of the biggest challenges for space research."

For the last 50 years, and since the accidental discovery of the Van Allen belts at the beginning of the space age, forecasting this space radiation has become essential to the operation of satellites and human exploration in space.

The Van Allen belts, named after their discoverer, are regions within the magnetosphere where high-energy protons and electrons are trapped by Earth's magnetic field. Known since 1958, these regions were historically classified into two inner and outer belts. However, in 2013, NASA's Van Allen Probes reported an unexplained third Van Allen belt that had not previously been observed. This third Van Allen belt lasted only a few weeks before it vanished, and its cause remained inexplicable.

Mann is co-investigator on the NASA Van Allen Probes mission. One of his team's main objectives is to model the process by which plasma waves in the magnetosphere control the dynamics of the intense relativistic particles in the Van Allen belts--with one of the goals of the Van Allen Probes mission being to develop sufficient understanding to reach the point of predictability. The appearance of the third Van Allen belt, one of the first major discoveries of the Van Allen Probes era, had continued to puzzle scientists with ever increasingly complex explanation models being developed. However, the explanation announced today shows that once the effects of these huge ULF waves are included, everything falls into place.

"We have discovered a very elegant explanation for the dynamics of the third belt," says Mann. "Our results show a remarkable simplicity in belt response once the dominant processes are accurately specified."

Many of the services we rely on today, such as GPS and satellite-based telecommunications, are affected by radiation within the Van Allen belts. Radiation in the form of high-energy electrons, often called "satellite killer" electrons because of their threat to satellites, is a high profile focus for the International Living with a Star (ILWS) Program and international cooperation between multiple international space agencies. Recent socio-economic studies of the impact of a severe space weather storm have estimated that the cost of the overall damage and follow-on impacts on space-based and terrestrial infrastructure could be as large as high as $2 trillion USD.

Politicians are also starting to give serious consideration to the risk from space weather. The White House recently announced the implementation of a Space Weather Action Plan highlighting the importance of space weather research like this recent discovery. The action plan seeks to mitigate the effects of extreme space weather by developing specific actions targeting mitigation and promoting international collaboration.

Read more at Science Daily

Poisonous Lionfish May Invade Mediterranean

The lionfish, a tropical creature with poisonous barbs and a painful sting that can kill humans in rare cases, may be spreading in the Mediterranean, a conservation group warned Monday.

The International Union for the Conservation of Nature (UICN) said the fish had been spotted in waters around Turkey and Cyprus in the eastern Mediterranean.

"That shows that the fish is spreading, and that's a cause for concern," Maria del Mar Otero of the UICN told AFP.

The highly invasive, predatory fish, also known as the Devil Firefish, is a native of the South Pacific and Indian Ocean.

Stings from its barbs are rarely fatal to humans, but can cause extreme pain, vomiting and respiratory paralysis.

Environmentalists fear that the fish's arrival in the eastern Mediterranean could decimate stocks of other fish, with knock-on effects on the rest of the marine environment.

Dr Carlos Jimenez, a marine biologist at the Cyprus Institute, said the species "could have a heavy negative impact on the ecosystems as well as on local economies".

Despite their conspicuous colours and slow movements, even sharks won't go near lionfish, giving them free rein to feed and wipe out other species that normally keep algae in check.

This can attract the arrival of new invasive species because of the weakening of the local fauna and flora, said Jimenez.

The voracious fish caused environmental havoc after it was introduced to the Caribbean.

Lionfish were first recorded in Cuba in 2007, and within two years, they were common in waters around the island, said Delmis Cabrera, a marine biologist at the National Aquarium in Havana.

The Association of Caribbean States organised a summit to discuss ways of combatting the fish's spread.

Cuba, Colombia and the Bahamas have encouraged their populations to start eating the fish to keep down numbers.

Read more at Discovery News

Bird Dad Seen Teaching Chicks to Sing

A new video captures a zebra finch father giving singing lessons to his sons, revealing how important it can be to pay attention to dad.

Birds, humans and many other vocal animals appear to be more influenced by parental communications than previously thought, as new research finds that youngsters can start learning from a parent very early in life, with sounds of parental yammering imprinted in memory nearly for perpetuity.

"For young animals, the early sensory experiences are very important and strongly affect brain development," co-author Shin Yanagihara, a scientist at the Okinawa Institute of Science and Technology Graduate University's Neuronal Mechanism for Critical Period Unit, said in a press release. "This stage is called the 'critical period' where the brain circuits are very flexible and can be easily changed and modified."

For the study, published in the journal Nature Communications, Yanagihara and colleague Yoko Yazaki-Sugiyama studied zebra finch interactions as well as the brains of young zebra finches as the little birds listened to dad sing. They also monitored the neuronal activity in the young birds' brains as they listened to their own songs, as well as those of other zebra finches and the songs of different songbird species.

The researchers found that some "non-selective neurons" responded to all songs, but that other "selective neurons" responded exclusively to dad's tunes.

The scientists also found that about 5 percent of the neurons in the young birds' higher auditory cortex -- a part of the brain associated with hearing -- reacted to dad's songs. The researchers identified 27 neurons that selectively respond to dad's song.

The location in the brain that the scientists pinpointed could therefore be where early sound memories are located in the brains of birds and in many other animals, including humans.

As for why this is important, consider that for us, learning a first language is nearly effortless. That's because we start learning from our parents or early caregivers before we can even remember. Their words and sounds are imprinted into our memory at a very early age.

Learning a new language later in life, on the other hand, is much more difficult. It usually involves a lot of hard work and the speaker may never have the same fluency as with the first language.

The same is true of songbirds. Watch as, over time, two zebra finch sons learn a song from their dad:

At first the young birds sing as though they are babbling, not copying dad's songs very well. Over time their singing becomes more precise, until they can even develop their own song that is based on dad's, but is distinctive to the individual.

All of this is critical for the birds' future lives. Males are the singers in this species, and use their songs to attract mates. In short, a whole new generation of little birds relies upon such singing prowess.

The brain mechanisms during "the critical period" of learning vocalizations are still not very well understood, but the new findings could help show how the brain circuit is shaped during this early stage of development. They also shed light on how these neuronal circuits contribute to higher brain function in adulthood.

Read more at Discovery News

E.T. Phones Earth? Not for 1,500 Years

Aliens may be mediocre just like Earthlings, which could explain why humanity hasn't heard from advanced civilizations yet. If life on this planet develops at an average pace, rather than an exceptionally slow pace, then extraterrestrial life likely followed a similar path.

Like humanity, average civilizations have barely scratched the surface of galactic communication, so humans shouldn't start to worry about whether they're alone for another 1,500 years or so.

"Communicating with anybody is an incredibly slow, long-duration endeavor," said Evan Solomonides at a press conference June 14 at the American Astronomical Society's summer meeting in San Diego, California. Solomonides is an undergraduate student at Cornell University in New York, where he worked with Cornell radio astronomer Yervant Terzian to explore the mystery of the Fermi paradox: If life is abundant in the universe, the argument goes, it should have contacted Earth, yet there's no definitive sign of such an interaction.

 Solomonides said the enormous size of the galaxy means the silence comes as no surprise.

"Space is very big. It takes a long time to reach anyone, even at the speed of light," he said.

When Enrico Fermi formulated his namesake paradox in the 1950s, planets around other stars were only hypothetical. Today, scientists suspect that nearly every sun has at least one if not more worlds, dramatically increasing the chances for life to have evolved throughout the universe. However, for some people, the lack of confirmed greeting from another civilization suggests that life may not be so common after all.

Solomonides applied the mediocrity principle — the idea that Earth's attributes are likely common in the rest of the universe, rather than unusual — to the Fermi paradox. Scientists think that Earth is an average planet around an average star, orbiting in an average place within an average galaxy.

"There's nothing even remotely special about where we are in the universe, or even in the galaxy," Solomonides said.

The 1936 Berlin Olympic games broadcast was the first radio signal strong enough to leave Earth. Traveling at the speed of light, this program is the leading edge of a bubble of broadcasts racing outward through space from Earth. But that signal has managed to travel only 80 light-years from the planet.

Solomonides said advanced life elsewhere in the universe is unlikely to have arisen much before life on Earth. That's because bodies like those of humans require a mixture of the heavy elements produced over the lifetimes of stars, and it takes several generations of star formation to produce the necessary quantities. As a result, civilizations capable of communicating throughout the galaxy wouldn't have started out much earlier than happened on Earth.

Based on the assumption that life and technology on Earth should have evolved at a relatively average pace, not significantly faster or slower than for other civilizations, Solomonides calculated the communication bubbles that life would produce throughout the galaxy. He found that, as of today, only about a tenth of 1 percent of the Milky Way would be blanketed by signals. With those numbers, it's likely that Earth won't hear from other life-forms for another 1,500 years.

"There could be life everywhere in the galaxy, and we still wouldn't know it," Solomonides said.

 In fact, "if we had been contacted by another civilization, we would actually be special."

That doesn't mean humanity should stop searching for signals or cut off broadcasts (though the rise of cable to carry television signals may mean that Earth is getting quieter anyway), Solomonides said. Instead, humans should keep broadcasting and listening in order to avoid missing the historic chance of contact, he said. People simply shouldn't expect results any time in the near future.

Even if, in the next 2,000 years, humans still haven't heard from other life-forms, that won't mean life doesn't exist throughout the galaxy, Solomonides said. He pointed out that communication requires the evolution of advanced life; molecular life won't be sending out signals, and so isn't considered in the search for extraterrestrial intelligence. Other scientists have suggested alien life may have evolved but then died out.

Read more at Discovery News

Jun 19, 2016

New type of meteorite linked to ancient asteroid collision

An ancient space rock discovered in a Swedish quarry is a type of meteorite never before found on Earth, scientists reported June 14 in the journal Nature Communications.

"In our entire civilization, we have collected over 50,000 meteorites, and no one has seen anything like this one before," said study co-author Qing-zhu Yin, professor of geochemistry and planetary sciences at the University of California, Davis. "Discovering a new type of meteorite is very, very exciting."

The new meteorite, called Ost 65, appears to be from the missing partner in a massive asteroid collision 470 million years ago. The collision sent debris falling to Earth over about a million years and may have influenced a great diversification of life in the Ordovician Period. One of the objects involved in this collision is well-known: It was the source of L-chondrites, still the most common type of meteorite. But the identity of the object that hit it has been a mystery.

Ost 65 was discovered in Sweden's Thorsberg quarry, source of more than 100 fossil meteorites. Measuring just under 4 inches wide, it looks like a gray cow patty plopped into a pristine layer of fossil-rich pink limestone. The Ost 65 rock is called a fossil meteorite because the original rock is almost completely altered except for a few hardy minerals -- spinels and chromite. Analyses of chromium and oxygen isotopes in the surviving minerals allowed the researchers to conclude the Ost 65 meteorite is chemically distinct from all known meteorite types.

By measuring how long Ost 65 was exposed to cosmic rays, the team established that it traveled in space for about a million years before it fell to Earth 470 million years ago. This timeline matches up with L-chondrite meteorites found in the quarry, leading the study authors to suggest the rock is a fragment of the other object from the Ordovician collision. The original object may have been destroyed during the collision, but it's also possible that the remains are still out in space.

Meteorites may have influenced evolution

Researchers think that about 100 times as many meteorites slammed into Earth during the Ordovician compared with today, thanks to the massive collision in the asteroid belt. This rain of meteorites may have opened new environmental niches for organisms, thus boosting both the diversity and complexity of life on Earth.

"I think this shows the interconnectedness of the entire solar system in space and time, that a random collision 470 million years ago in the asteroid belt could dictate the evolutionary path of species here on Earth," Yin said.

The study was led by Birger Schmitz, of Lund University in Sweden. Yin, of UC Davis, together with his postdoctoral fellow Matthew Sanborn, made the very precise measurement of chromium in tiny mineral grains within the meteorite. Researchers from the University of Hawaii at Manoa analyzed its oxygen isotopes.

Read more at Science Daily

New imaging method reveals nanoscale details about DNA

A new imaging technique allows researchers to image both the position and orientation of single fluorescent molecules attached to DNA.
Researchers have developed a new enhanced DNA imaging technique that can probe the structure of individual DNA strands at the nanoscale. Since DNA is at the root of many disease processes, the technique could help scientists gain important insights into what goes wrong when DNA becomes damaged or when other cellular processes affect gene expression.

The new imaging method builds on a technique called single-molecule microscopy by adding information about the orientation and movement of fluorescent dyes attached to the DNA strand.

W. E. Moerner, Stanford University, USA, is the founder of single-molecule spectroscopy, a breakthrough method from 1989 that allowed scientists to visualize single molecules with optical microscopy for the first time. Of the 2014 Nobel Laureates for optical microscopy beyond the diffraction limit (Moerner, Hell & Betzig), Moerner and Betzig used single molecules to image a dense array of molecules at different times.

In The Optical Society's journal for high impact research, Optica, the research team led by Moerner describes their new technique and demonstrates it by obtaining super-resolution images and orientation measurements for thousands of single fluorescent dye molecules attached to DNA strands.

"You can think of these new measurements as providing little double-headed arrows that show the orientation of the molecules attached along the DNA strand," said Moerner. "This orientation information reports on the local structure of the DNA bases because they constrain the molecule. If we didn't have this orientation information the image would just be a spot."

Adding more nanoscale information

A strand of DNA is a very long, but narrow string, just a few nanometers across. Single-molecule microscopy, together with fluorescent dyes that attach to DNA, can be used to better visualize this tiny string. Until now, it was difficult to understand how those dyes were oriented and impossible to know if the fluorescent dye was attached to the DNA in a rigid or somewhat loose way.

Adam S. Backer, first author of the paper, developed a fairly simple way to obtain orientation and rotational dynamics from thousands of single molecules in parallel. "Our new imaging technique examines how each individual dye molecule labeling the DNA is aligned relative to the much larger structure of DNA," said Backer. "We are also measuring how wobbly each of these molecules is, which can tell us whether this molecule is stuck in one particular alignment or whether it flops around over the course of our measurement sequence."

The new technique offers more detailed information than today's so-called "ensemble" methods, which average the orientations for a group of molecules, and it is much faster than confocal microscopy techniques, which analyze one molecule at a time. The new method can even be used for molecules that are relatively dim.

Because the technique provides nanoscale information about the DNA itself, it could be useful for monitoring DNA conformation changes or damage to a particular region of the DNA, which would show up as changes in the orientation of dye molecules. It could also be used to monitor interactions between DNA and proteins, which drive many cellular processes.

30,000 single-molecule orientations

The researchers tested the enhanced DNA imaging technique by using it to analyze an intercalating dye; a type of fluorescent dye that slides into the areas between DNA bases. In a typical imaging experiment, they acquire up to 300,000 single molecule locations and 30,000 single-molecule orientation measurements in just over 13 minutes. The analysis showed that the individual dye molecules were oriented perpendicular to the DNA strand's axis and that while the molecules tended to orient in this perpendicular direction, they also moved around within a constrained cone.

The investigators next performed a similar analysis using a different type of fluorescent dye that consists of two parts: one part that attaches to the side of the DNA and a fluorescent part that is connected via a floppy tether. The enhanced DNA imaging technique detected this floppiness, showing that the method could be useful in helping scientists understand, on a molecule by molecule basis, whether different labels attach to DNA in a mobile or fixed way.

In the paper, the researchers demonstrated a spatial resolution of around 25 nanometers and single-molecule orientation measurements with an accuracy of around 5 degrees. They also measured the rotational dynamics, or floppiness, of single-molecules with an accuracy of about 20 degrees.

How it works

To acquire single-molecule orientation information, the researchers used a well-studied technique that adds an optical element called an electro-optic modulator to the single-molecule microscope. For each camera frame, this device changed the polarization of the laser light used to illuminate all the fluorescent dyes.

Since fluorescent dye molecules with orientations most closely aligned with the laser light's polarization will appear brightest, measuring the brightness of each molecule in each camera frame allowed the researchers to quantify orientation and rotational dynamics on a molecule-by-molecule basis. Molecules that switched between bright and dark in sequential frames were rigidly constrained at a particular orientation while those that appeared bright for sequential frames were not rigidly holding their orientation.

Read more at Science Daily