Large Antarctic Ice Shelf, home to a UK research station, is about to break apart

This is the Halloween Crack, which was discovered on 31 October 2016.

Glaciology experts have issued evidence that a large section of the Brunt Ice Shelf in Antarctica, which is home to the British Antarctic Survey's Halley Research Station, is about break off.

The rifting started several years ago and is now approaching its final phase. In anticipation of the iceberg breaking away, the research station, which is currently unmanned, has been relocated to a safer location on the ice shelf, meaning there is no danger posed to personnel.

The iceberg, measuring over 1,500 square kilometres -- which is twice the size of New York City -- is expected to break away from the Brunt Ice Shelf in as little as a few months, when two large cracks which have been growing over the past seven years meet.

Now academics from Northumbria University, in Newcastle upon Tyne, UK, in collaboration with scientists from ENVEO, a remote sensing company in Austria, have submitted new research to the journal The Cryosphere, which shows that the break-off is part of the ice shelf's natural lifecycle, and that similar events may have occurred in the past.

As Professor Hilmar Gudmundsson of Northumbria explains: "I have been carrying out research in this area for more than 15 years and have been monitoring the growth of the cracks since they first emerged in 2012.

"Satellite images of the changes in the ice shelf have been shared online and there has been much speculation about the cause of this movement and the impact the iceberg will have when it breaks away.

"However, what many people do not realise is that this is a natural process and something which has happened time and again. We recognise that climate change is a serious problem which is having an impact around the world, and particularly in the Antarctic. However, there is no indication from our research that this particular event is related to climate change.

"We have been tracking the movement of the ice shelf for many years and our modelling indicates that this breakaway is entirely expected. That is why in 2014 we recommended that the Halley Research Station was moved to a new and safe location on the ice shelf.

"Our field observations and modelling has meant that the station was safely relocated with no danger to the scientists using it and minimal disruption to the research taking place."

The Brunt Ice Shelf is a large floating area of ice, around 150m to 250m thick, and is made up of freshwater ice which originally fell as snow further inland. The ice shelf rests on top of the Weddell Sea and flows off the mainland, moving outwards from the centre of Antarctica.

As ice shelves are afloat, any icebergs that form as a result of fractures in the ice do not contribute to sea level rise. "Once the iceberg breaks away from the Brunt Ice Shelf it is likely to drift towards the west and slowly break up into smaller icebergs," explains Dr Jan De Rydt, also of Northumbria University.

This isn't the first time a large piece of ice shelf has broken away in Antarctica. The Pine Island Ice Shelf in West Antarctica has seen several large sections break off in recent years, and the Larsen C Ice Shelf to the West of the Brunt Ice Shelf has lost a section more than 3,600 square miles due to calving -- when ice chunks break from the edge of a glacier -- in 2017.

And there is historic evidence to show the Brunt Ice Shelf has seen similar large calving events in the past. As Professor Gudmundsson explains: "Maps drawn by Shackleton and Wordie during their expedition to the Brunt Ice Shelf in 1915 show that, at that time, the ice shelf was quite extended. However, by the time the Halley Research Station was established in the 1950s the reach of the ice shelf was much shorter, indicating that a large iceberg must have broken away at some point after 1915. This further backs up our research that this type of event is historically consistent and part of the natural cycle and movement of the ice shelf."

Dr De Rydt and Professor Gudmundsson's paper, Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice-shelf geometry, is currently undergoing peer review in the European Geosciences Union journal The Cryosphere.

The paper is co-authored by Thomas Nagler and Jan Wuite of ENVEO (Environmental Earth Observation), in Innsbruck, Austria, who have worked closely with Professor Gudmundsson and Dr De Rydt during the research. ENVEO is a world-leader in processing satellite data for monitoring changes in the global snow and ice cover. The two teams have been collaborating together for several years on a number of projects, with scientists from ENVEO using satellite imagery to extract data about the changing speed of the ice shelf, which is then shared with researchers at Northumbria University for modelling and interpretation.

Dr Jan Wuite of ENVEO said: "Thanks to the Copernicus Sentinel-1 and Sentinel-2 satellites we can now continuously monitor the movement of the ice shelf and the propagation of the cracks in great detail and in near real-time. These observational data are very useful for improving existing ice flow models."

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Unexpected rain on sun links two solar mysteries

Mason's article analyzed three observations of Raining Null-Point Topologies, or RNTPs, a previously overlooked magnetic structure shown here in two wavelengths of extreme ultraviolet light. The coronal rain observed in these comparatively small magnetic loops suggests that the corona may be heated within a far more restricted region than previously expected.

For five months in mid 2017, Emily Mason did the same thing every day. Arriving to her office at NASA's Goddard Space Flight Center in Greenbelt, Maryland, she sat at her desk, opened up her computer, and stared at images of the Sun -- all day, every day. "I probably looked through three or five years' worth of data," Mason estimated. Then, in October 2017, she stopped. She realized she had been looking at the wrong thing all along.

Mason, a graduate student at The Catholic University of America in Washington, D.C., was searching for coronal rain: giant globs of plasma, or electrified gas, that drip from the Sun's outer atmosphere back to its surface. But she expected to find it in helmet streamers, the million-mile tall magnetic loops -- named for their resemblance to a knight's pointy helmet -- that can be seen protruding from the Sun during a solar eclipse. Computer simulations predicted the coronal rain could be found there. Observations of the solar wind, the gas escaping from the Sun and out into space, hinted that the rain might be happening. And if she could just find it, the underlying rain-making physics would have major implications for the 70-year-old mystery of why the Sun's outer atmosphere, known as the corona, is so much hotter than its surface. But after nearly half a year of searching, Mason just couldn't find it. "It was a lot of looking," Mason said, "for something that never ultimately happened."

The problem, it turned out, wasn't what she was looking for, but where. In a paper published today in the Astrophysical Journal Letters, Mason and her coauthors describe the first observations of coronal rain in a smaller, previously overlooked kind of magnetic loop on the Sun. After a long, winding search in the wrong direction, the findings forge a new link between the anomalous heating of the corona and the source of the slow solar wind -- two of the biggest mysteries facing solar science today.

How It Rains on the Sun

Observed through the high-resolution telescopes mounted on NASA's SDO spacecraft, the Sun -- a hot ball of plasma, teeming with magnetic field lines traced by giant, fiery loops -- seems to have few physical similarities with Earth. But our home planet provides a few useful guides in parsing the Sun's chaotic tumult: among them, rain.

On Earth, rain is just one part of the larger water cycle, an endless tug-of-war between the push of heat and pull of gravity. It begins when liquid water, pooled on the planet's surface in oceans, lakes, or streams, is heated by the Sun. Some of it evaporates and rises into the atmosphere, where it cools and condenses into clouds. Eventually, those clouds become heavy enough that gravity's pull becomes irresistible and the water falls back to Earth as rain, before the process starts anew.

On the Sun, Mason said, coronal rain works similarly, "but instead of 60-degree water you're dealing with a million-degree plasma." Plasma, an electrically-charged gas, doesn't pool like water, but instead traces the magnetic loops that emerge from the Sun's surface like a rollercoaster on tracks. At the loop's foot points, where it attaches to the Sun's surface, the plasma is superheated from a few thousand to over 1.8 million degrees Fahrenheit. It then expands up the loop and gathers at its peak, far from the heat source. As the plasma cools, it condenses and gravity lures it down the loop's legs as coronal rain.

Mason was looking for coronal rain in helmet streamers, but her motivation for looking there had more to do with this underlying heating and cooling cycle than the rain itself. Since at least the mid-1990s, scientists have known that helmet streamers are one source of the slow solar wind, a comparatively slow, dense stream of gas that escapes the Sun separately from its fast-moving counterpart. But measurements of the slow solar wind gas revealed that it had once been heated to an extreme degree before cooling and escaping the Sun. The cyclical process of heating and cooling behind coronal rain, if it was happening inside the helmet streamers, would be one piece of the puzzle.

The other reason connects to the coronal heating problem -- the mystery of how and why the Sun's outer atmosphere is some 300 times hotter than its surface. Strikingly, simulations have shown that coronal rain only forms when heat is applied to the very bottom of the loop. "If a loop has coronal rain on it, that means that the bottom 10% of it, or less, is where coronal heating is happening," said Mason. Raining loops provide a measuring rod, a cutoff point to determine where the corona gets heated. Starting their search in the largest loops they could find -- giant helmet streamers -- seemed like a modest goal, and one that would maximize their chances of success.

She had the best data for the job: Images taken by NASA's Solar Dynamics Observatory, or SDO, a spacecraft that has photographed the Sun every twelve seconds since its launch in 2010. But nearly half a year into the search, Mason still hadn't observed a single drop of rain in a helmet streamer. She had, however, noticed a slew of tiny magnetic structures, ones she wasn't familiar with. "They were really bright and they kept drawing my eye," said Mason. "When I finally took a look at them, sure enough they had tens of hours of rain at a time."

At first, Mason was so focused on her helmet streamer quest that she made nothing of the observations. "She came to group meeting and said, 'I never found it -- I see it all the time in these other structures, but they're not helmet streamers,'" said Nicholeen Viall, a solar scientist at Goddard, and a coauthor of the paper. "And I said, 'Wait...hold on. Where do you see it? I don't think anybody's ever seen that before!'"

A Measuring Rod for Heating

These structures differed from helmet streamers in several ways. But the most striking thing about them was their size.

"These loops were much smaller than what we were looking for," said Spiro Antiochos, who is also a solar physicist at Goddard and a coauthor of the paper. "So that tells you that the heating of the corona is much more localized than we were thinking."

While the findings don't say exactly how the corona is heated, "they do push down the floor of where coronal heating could happen," said Mason. She had found raining loops that were some 30,000 miles high, a mere two percent the height of some of the helmet streamers she was originally looking for. And the rain condenses the region where the key coronal heating can be happening. "We still don't know exactly what's heating the corona, but we know it has to happen in this layer," said Mason.

A New Source for the Slow Solar Wind

But one part of the observations didn't jibe with previous theories. According to the current understanding, coronal rain only forms on closed loops, where the plasma can gather and cool without any means of escape. But as Mason sifted through the data, she found cases where rain was forming on open magnetic field lines. Anchored to the Sun at only one end, the other end of these open field lines fed out into space, and plasma there could escape into the solar wind. To explain the anomaly, Mason and the team developed an alternative explanation -- one that connected rain on these tiny magnetic structures to the origins of the slow solar wind.

In the new explanation, the raining plasma begins its journey on a closed loop, but switches -- through a process known as magnetic reconnection -- to an open one. The phenomenon happens frequently on the Sun, when a closed loop bumps into an open field line and the system rewires itself. Suddenly, the superheated plasma on the closed loop finds itself on an open field line, like a train that has switched tracks. Some of that plasma will rapidly expand, cool down, and fall back to the Sun as coronal rain. But other parts of it will escape -- forming, they suspect, one part of the slow solar wind.

Mason is currently working on a computer simulation of the new explanation, but she also hopes that soon-to-come observational evidence may confirm it. Now that Parker Solar Probe, launched in 2018, is traveling closer to the Sun than any spacecraft before it, it can fly through bursts of slow solar wind that can be traced back to the Sun -- potentially, to one of Mason's coronal rain events. After observing coronal rain on an open field line, the outgoing plasma, escaping to the solar wind, would normally be lost to posterity. But no longer. "Potentially we can make that connection with Parker Solar Probe and say, that was it," said Viall.

Digging Through the Data

As for finding coronal rain in helmet streamers? The search continues. The simulations are clear: the rain should be there. "Maybe it's so small you can't see it?" said Antiochos. "We really don't know."

But then again, if Mason had found what she was looking for she might not have made the discovery -- or have spent all that time learning the ins and outs of solar data.

Read more at Science Daily

Like old photographs, memories fade over time

Like old photographs, memories fade in quality over time -- a surprising finding for a team of Boston College researchers who expected recollections would become less accurate, but found people also report declines in the vibrancy and visual qualities of their memories.

When people remember the past, they remember it with varying degrees of clarity, said Boston College Assistant Professor of Psychology Maureen Ritchey, a cognitive neuroscientist and co-author of the study, published in an online edition of the journal Psychological Science.

Sometimes people remember lots of details about an event, as if they are reliving the moment as it happened, said Ritchey. Other times, it seems like the memory has faded, and the details are fuzzy. Prior memory research has shown that emotionally significant events -- like a car accident -- are remembered more vividly than everyday events.

"We wanted to know whether this feeling of memory vividness is related to not just what is remembered, but how it is remembered -- the visual quality of the memory," said Ritchey, who conducted the study with Boston College Professor of Psychology Elizabeth Kensinger and post-doctoral researcher Rose Cooper.

As events are stored in memory or forgotten, the team asked, how do their visual features change? Ritchey said people reported changes to their memories akin to using a filter to edit a picture.

"A simple analogy is what happens when you post a photo on Instagram," Ritchey said. "You're cued to apply a filter that changes the brightness or color saturation of the image. In our study, we asked if forgetting is like applying a filter to past experience, and whether or not the emotional significance of the event would change which filter you apply."

In three experiments, participants studied emotionally negative and neutral images that varied in visual quality -- luminance and color saturation. They then reconstructed the visual qualities of each image in a subsequent test.

The findings revealed that memories were recollected as less visually vibrant than they were encoded, demonstrating a novel memory-fading effect, the researchers reported.

Negative emotions subjects experienced when viewing the images increased the likelihood that images would be accurately remembered but did not influence memory fading. In addition, subjective ratings of memory vividness were lower for less accurate memories and for memories that had visually faded, the team found.

These findings provide evidence that the vibrancy of low-level details -- such as colors and shapes associated with an event -- fade in memory while the gist of the experience is retained.

People may remember going to a music festival and watching their favorite band, but the intensity of that sensory experience, including the bright stage lights and strength of the bass, will slowly fade.

"We found that memories seem to literally fade: people consistently remembered visual scenes as being less vibrant than they were originally experienced," said Cooper. "We had expected that memories would get less accurate after a delay, but we did not expect that there would be this qualitative shift in the way that they were remembered."

The fading effect happened less for memories that were rated as subjectively stronger. "We were also surprised to find that emotional memories did not influence the amount of fading, only the likelihood with which people remembered the images at all," she added.

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Scientists discover first organism with chlorophyll genes that doesn't photosynthesize

Corallicolids are found in 70 percent of corals around the world.

For the first time scientists have found an organism that can produce chlorophyll but does not engage in photosynthesis.

The peculiar organism is dubbed 'corallicolid' because it is found in 70 per cent of corals around the world and may provide clues as to how to protect coral reefs in the future.

"This is the second most abundant cohabitant of coral on the planet and it hasn't been seen until now," says Patrick Keeling, a University of British Columbia botanist and senior researcher overseeing the study published in Nature. "This organism poses completely new biochemical questions. It looks like a parasite, and it's definitely not photosynthetic. But it still makes chlorophyll."

Chlorophyll is the green pigment found in plants and algae that allows them to absorb energy from sunlight during photosynthesis.

"Having chlorophyll without photosynthesis is actually very dangerous because chlorophyll is very good at capturing energy, but without photosynthesis to release the energy slowly it is like living with a bomb in your cells," Keeling says.

Corallicolids live in the gastric cavity of a wide array of corals responsible for building reefs, as well as black corals, fan corals, mushroom corals, and anemones. They are an apicomplexan, part of a vast group of parasites that have a cellular compartment called a plastid, which is the part of plant and algal cells where photosynthesis takes place. The most famous apicomplexan is the parasite responsible for malaria.

More than a decade ago, photosynthetic algae related to apicomplexans were discovered in healthy corals, indicating they might have evolved from benign photosynthesising organisms attached to corals before turning into the parasites we know today.

Ecological data showed that coral reefs contain several apicomplexans, but corallicolids, the most most common one, had not been studied until now. The organism has revealed a new puzzle: not only does it have a plastid, but it contains all four plastid genes used in chlorophyll production.

"It's quite a head scratcher," says Waldan Kwong, a UBC postdoctoral research fellow and lead author of the study. "We don't know why these organisms are holding on to these photosynthesis genes. There's some novel biology going on here, something we haven't seen before."

Read more at Science Daily

Electricity-conducting bacteria yield secret to tiny batteries, big medical advances

An atomic model for the microbial nanowires that conduct electricity is in the foreground, while two bacteria are seen in the electron micrograph in the background, surrounded by the nanowires.

Scientists have made a surprising discovery about how strange bacteria that live in soil and sediment can conduct electricity. The bacteria do so, the researchers determined, through a seamless biological structure never before seen in nature -- a structure scientists can co-opt to miniaturize electronics, create powerful-yet-tiny batteries, build pacemakers without wires and develop a host of other medical advances.

Scientists had believed Geobacter sulfurreducens conducted electricity through common, hair-like appendages called pili. Instead, a researcher at the University of Virginia School of Medicine and his collaborators have determined that the bacteria transmit electricity through immaculately ordered fibers made of an entirely different protein. These proteins surround a core of metal-containing molecules, much like an electric cord contains metal wires. This "nanowire," however, is 100,000 times smaller than the width of a human hair.

This tiny-but-tidy structure, the researchers believe, could be tremendously useful for everything from harnessing the power of bioenergy to cleaning up pollution to creating biological sensors. It could actually serve as the bridge between electronics and living cells.

"There are all sorts of implanted medical devices that are connected to tissue, like pacemakers with wires, and this could lead to applications where you have miniature devices that are actually connected by these protein filaments," said UVA's Edward H. Egelman, PhD. "We can now imagine the miniaturization of many electronic devices generated by bacteria, which is pretty amazing."

Small but Effective

Geobacter bacteria play important roles in the soil, including facilitating mineral turnover and even cleaning up radioactive waste. They survive in environments without oxygen, and they use nanowires to rid themselves of excess electrons in what can be considered their equivalent to breathing. These nanowires have fascinated scientists, but it is only now that researchers at UVA, Yale and the University of California, Irvine, have been able to determine how G. sulfurreducens uses these organic wires to transmit electricity.

"The technology [to understand nanowires] didn't exist until about five years ago, when advances in cryo-electron microscopy allowed high resolution," said Egelman, of UVA's Department of Biochemistry and Molecular Genetics. "We have one of these instruments here at UVA, and, therefore, the ability to actually understand at the atomic level the structure of these filaments. ... So this is just one of the many mysteries that we've now been able to solve using this technology, like the virus that can survive in boiling acid, and there will be others."

Read more at Science Daily

Novel Hawaiian communities operate similarly to native ecosystems

In Hawaii's novel seed dispersal networks, introduced birds primarily disperse introduced plants. In a new study published in Science, research shows these novel networks operate very similarly to native communities worldwide.

On the Hawaiian island of Oahu, it is possible to stand in a lush tropical forest that doesn't contain a single native plant. The birds that once dispersed native seeds are almost entirely gone too, leaving a brand-new ecological community composed of introduced plants and birds. In a first-of-its-kind study published today in Science, researchers demonstrate that these novel communities are organized in much the same way as native communities worldwide.

The discovery comes after an exhaustive examination of bird diets across Oahu and a subsequent network analysis describing bird-plant interactions on the island. Unexpectedly, the analysis showed introduced birds have developed complex patterns of interactions with plants, most of them non-native to the island. And when bird-plant interactions in Oahu were compared to native-dominated ecosystems around the world, they were strikingly similar.

"These birds on Oahu aren't interacting with these invasive plants randomly. They're actually selecting certain plants. What's interesting about this is that these birds didn't co-evolve with these plants. We think of specialization as a co-evolved trait that develops over millennia, but we are seeing it in completely novel ecosystems and in species that have only lived together for less than 100 years," says Jinelle Sperry, wildlife biologist for the U.S. Army Engineer Research and Development Center, adjunct professor in the Department of Natural Resources and Environmental Sciences (NRES) at the University of Illinois, and co-author on the Science study.

The researchers also tested the stability of these bird-plant interactions by simulating the extinction of plant species. That result was surprising, as well.

"We were trying to determine how fast the birds would go extinct if you remove plants in a given sequence. I simulated this for Oahu and native-dominated communities and compared," says Jeferson Vizentin-Bugoni, lead author on the study and postdoctoral researcher with the U.S. Army Engineer Research and Development Center and NRES at U of I. "The rates at which Oahu communities collapsed in the simulations were very similar to native communities. This means that now these novel networks in Hawaii are as stable as native-dominated communities."

Although the results could be interpreted as a silver lining to the ever-increasing threat of invasive species and extinctions, the researchers call for caution. First, there's the fact that they didn't find evidence of a single native bird consuming a single native seed, even after examining fecal material from more than three thousand birds.

"Because all native fruit-eating birds are extinct on Oahu, we knew chances were low that we'd find native birds consuming native seeds," Sperry says. "But to have caught that many birds over three years and not have found a single native interaction is pretty astounding."

Rather than consuming native seeds, the study showed introduced birds are predominantly eating and spreading invasive plants around the island, compounding an already hard-to-solve problem.

Vizentin-Bugoni says, "Introduced birds are acting as a double-edged sword. Because there are no native dispersers left, they are the only hope left for native plants, but at the same time, they are dispersing a lot of introduced plants."

Interestingly, the birds ate different groups of invasive plants in different locations on the island. This ability to "partner switch" has important implications for restoration, Sperry says.

"These birds are really flexible in what they'll consume, but across sites, they're primarily eating invasive plant species. Because of that, in restored sites, we need to really entice birds to eat native fruits. They're the only ones left to help move seeds of native plants. We need to use active management and multiple restoration tools or we won't have a self-sustaining restoration," she notes.

Finally, although the novel community might have some of the same properties as a native system, the researchers stress it is not the same. Importantly, the community is dramatically less diverse. Study results indicate just four bird species are responsible for moving the bulk of the plants around the island.

Before Hawaii became the extinction and species-invasion capital of the world, its ecological communities were much more diverse. Experts estimate that in the last 700 years, 77 species and subspecies of birds in the Hawaiian Archipelago have gone extinct, accounting for 15 percent of bird extinctions worldwide.

"Many Hawaiian communities now lack birds with the appropriate beak shapes or sizes to consume seeds of certain native plants. Those plants are out of luck with regards to dispersal," says Jason Gleditsch, a co-author on the study and doctoral student in NRES at U of I.

Read more at Science Daily

Otherworldly mirror pools and mesmerizing landscapes discovered on ocean floor

The hydrothermal vent field featured numerous volcanic flanges that create the illusion of looking at a mirror when observing the superheated (366ºC) hydrothermal fluids beneath them. The minerals across the features were laden with metals and the fluids were highly sulfidic, yet these sites were teeming with biodiversity and potentially novel fauna.

While exploring hydrothermal vent and cold seep environments, Dr. Mandy Joye (University of Georgia), and her interdisciplinary research team discovered large venting mineral towers that reach up to 23 meters in height and 10 meters across. These towers featured numerous volcanic flanges that create the illusion of looking at a mirror when observing the superheated (366ºC) hydrothermal fluids beneath them. The minerals across the features were laden with metals and the fluids were highly sulfidic, yet these sites were teeming with biodiversity and potentially novel fauna.

"We discovered remarkable towers where every surface was occupied by some type of life. The vibrant colors found on the 'living rocks' was striking, and reflects a diversity in biological composition as well as mineral distributions," said Dr. Joye. "This is an amazing natural laboratory to document incredible organisms and better understand how they survive in extremely challenging environments. Unfortunately, even in these remote and beautiful environments we saw copious amounts of trash including fishing nets, deflated Mylar balloons, and even a discarded Christmas trees. This provided a stark juxtaposition next to the spectacular mineral structures and biodiversity."

The expedition was an unprecedented study of hydrothermal and gas plumes, with researchers using advanced technology including 4K deep-sea underwater cameras and radiation tracking devices, as well as sediment and fluid samplers working via a remotely operated vehicle, ROV SuBastian. To get a true measure of methane and other volatile substances existing in the deep sea, scientists need to capture the samples at the source. The scientists were able to do this with a unique osmo sampler, a device that draws hydrothermal fluids into small capillary-like tubing, mounted onto the ROV. Several other in-situ experiments were performed, including a high throughput water filtration for viruses that allowed the team to reduce processing bias.

From super-hot hydrothermal vents to slowly discharging cold seeps, the common thread of the sample collections involved studies of methane cycling. Hydrothermal fluids and gas plume samples all contained highly elevated concentrations of methane and surface-breaching methane hydrate mounds. Methane is a potent atmospheric greenhouse gas, 30 times the strength of carbon dioxide, and this study will advance the knowledge of the biological storage for methane in water column and sediment systems.

"It is a different world down there. Each dive feels like floating into a science fiction film," said Schmidt Ocean Institute Cofounder Wendy Schmidt. "The complex layers of data we've collected aboard Falkor during this expedition will help tell the story of this remote place and bring it to public attention. Witnessing these remarkable oceanscapes, we are reminded that although they are out of our everyday sight, they are hardly immune from human impact. Our hope is to inspire people to learn more and care more about our ocean."

The team will now spend the next few months analyzing samples and plans to publicly share the results. As the different data sets are synthesized, scientists will generate a more complete understanding of the Gulf of California system. This understanding will be applicable to oceanic environments around the globe, as well as allow scientists to identify and frame exciting new questions.

Read more at Science Daily

Poverty leaves a mark on our genes

Rendering of DNA.

A new Northwestern University study challenges prevailing understandings of genes as immutable features of biology that are fixed at conception.

Previous research has shown that socioeconomic status (SES) is a powerful determinant of human health and disease, and social inequality is a ubiquitous stressor for human populations globally. Lower educational attainment and/or income predict increased risk for heart disease, diabetes, many cancers and infectious diseases, for example. Furthermore, lower SES is associated with physiological processes that contribute to the development of disease, including chronic inflammation, insulin resistance and cortisol dysregulation.

In this study, researchers found evidence that poverty can become embedded across wide swaths of the genome. They discovered that lower socioeconomic status is associated with levels of DNA methylation (DNAm) -- a key epigenetic mark that has the potential to shape gene expression -- at more than 2,500 sites, across more than 1,500 genes.

In other words, poverty leaves a mark on nearly 10 percent of the genes in the genome.

Lead author Thomas McDade said this is significant for two reasons.

"First, we have known for a long time that SES is a powerful determinant of health, but the underlying mechanisms through which our bodies 'remember' the experiences of poverty are not known," said McDade, professor of anthropology in the Weinberg College of Arts and Sciences at Northwestern and director of the Laboratory for Human Biology Research.

"Our findings suggest that DNA methylation may play an important role, and the wide scope of the associations between SES and DNAm is consistent with the wide range of biological systems and health outcomes we know to be shaped by SES."

Secondly, said McDade, also a faculty fellow at Northwestern's Institute for Policy Research, experiences over the course of development become embodied in the genome, to literally shape its structure and function.

"There is no nature vs. nurture," he adds.

McDade said he was surprised to find so many associations between socioeconomic status and DNA methylation, across such a large number of genes.

"This pattern highlights a potential mechanism through which poverty can have a lasting impact on a wide range of physiological systems and processes," he said.

Follow-up studies will be needed to determine the health consequences of differential methylation at the sites the researchers identified, but many of the genes are associated with processes related to immune responses to infection, skeletal development and development of the nervous system.

Read more at Science Daily

Heavy metal planet fragment survives destruction from dead star

A planetary fragment orbits the star SDSS J122859.93+104032.9, leaving a tail of gas in its wake.

A fragment of a planet that has survived the death of its star has been discovered by University of Warwick astronomers in a disc of debris formed from destroyed planets, which the star ultimately consumes.

The iron and nickel rich planetesimal survived a system-wide cataclysm that followed the death of its host star, SDSS J122859.93+104032.9. Believed to have once been part of a larger planet, its survival is all the more astonishing as it orbits closer to its star than previously thought possible, going around it once every two hours.

The discovery, reported in the journal Science, is the first time that scientists have used spectroscopy to discover a solid body in orbit around a white dwarf, using subtle variations in the emitted light to identify additional gas that the planetesimal is generating.

Using the Gran Telescopio Canarias in La Palma, the scientists studied a debris disc orbiting a white dwarf 410 light years away, formed by the disruption of rocky bodies composed of elements such as iron, magnesium, silicon, and oxygen -- the four key building blocks of the Earth and most rocky bodies. Within that disc they discovered a ring of gas streaming from a solid body, like a comet's tail. This gas could either be generated by the body itself or by evaporating dust as it collides with small debris within the disc.

The astronomers estimate that this body has to be at least a kilometre in size, but could be as large as a few hundred kilometres in diameter, comparable to the largest asteroids known in our Solar System.

White dwarfs are the remains of stars like our sun that have burnt all their fuel and shed their outer layers, leaving behind a dense core which slowly cools over time. This particular star has shrunk so dramatically that the planetesimal orbits within its sun's original radius. Evidence suggests that it was once part of a larger body further out in its solar system and is likely to have been a planet torn apart as the star began its cooling process.

Lead author Dr Christopher Manser, a Research Fellow in the Department of Physics, said: "The star would have originally been about two solar masses, but now the white dwarf is only 70% of the mass of our Sun. It is also very small -- roughly the size of the Earth -- and this makes the star, and in general all white dwarfs, extremely dense.

"The white dwarf's gravity is so strong -- about 100,000 times that of the Earth's -- that a typical asteroid will be ripped apart by gravitational forces if it passes too close to the white dwarf."

Professor Boris Gaensicke, co-author from the Department of Physics, adds: "The planetesimal we have discovered is deep into the gravitational well of the white dwarf, much closer to it than we would expect to find anything still alive. That is only possible because it must be very dense and/or very likely to have internal strength that holds it together, so we propose that it is composed largely of iron and nickel.

"If it was pure iron it could survive where it lives now, but equally it could be a body that is rich in iron but with internal strength to hold it together, which is consistent with the planetesimal being a fairly massive fragment of a planet core. If correct, the original body was at least hundreds of kilometres in diameter because it is only at that point planets begin to differentiate -- like oil on water -- and have heavier elements sink to form a metallic core."

The discovery offers a hint as to what planets may reside in other solar systems, and a glimpse into the future of our own.

Dr Christopher Manser said: "As stars age they grow into red giants, which 'clean out' much of the inner part of their planetary system. In our Solar System, the Sun will expand up to where the Earth currently orbits, and will wipe out Earth, Mercury, and Venus. Mars and beyond will survive and will move further out.

"The general consensus is that 5-6 billion years from now, our Solar System will be a white dwarf in place of the Sun, orbited by Mars, Jupiter, Saturn, the outer planets, as well as asteroids and comets. Gravitational interactions are likely to happen in such remnants of planetary systems, meaning the bigger planets can easily nudge the smaller bodies onto an orbit that takes them close to the white dwarf, where they get shredded by its enormous gravity.

"Learning about the masses of asteroids, or planetary fragments that can reach a white dwarf can tell us something about the planets that we know must be further out in this system, but we currently have no way to detect.

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Jurassic crocodile discovery sheds light on reptiles' family tree

A newly identified species of marine crocodile, Cricosaurus bambergensis, has given insights into how a group of ancient animals evolved. The ancestor of today's crocodiles belonged to a group of animals that developed a tail fin and paddle-like limbs for life in the sea.

A newly identified species of 150 million-year-old marine crocodile has given insights into how a group of ancient animals evolved.

The ancestor of today's crocodiles belonged to a group of animals that developed a tail fin and paddle-like limbs for life in the sea, resembling dolphins more than crocodiles.

These slender animals, which fed on fast-moving prey such as squid and small fish, lived during the Jurassic era in shallow seas and lagoons in what is now Germany. Related species have previously been found in Mexico and Argentina.

An international team of scientists, including researchers from Germany and the University of Edinburgh, identified the new species from a remarkably well-preserved skeleton.

The fossil was discovered in 2014 in a quarry near the town of Bamberg in Bavaria, Germany by a team from the Naturkunde-Museum Bamberg, where it is now housed. The species, Cricosaurus bambergensis, takes its name from the town.

Researchers compared the fossil with those from other museum collections, and confirmed that it was a previously unseen species.

The skeleton has several distinguishing features in its jaws, the roof of its mouth and tail, some of which have not been seen in any other species.

Experts created digital images of the fossil in high resolution, to enable further research. They expect the fossil will aid greater understanding of a wider family of ancient animals, known as metriorhynchid, to which this species belonged.

The research, carried out with Naturkunde-Museum Bielefeld, Eberhard-Karls Universität Tübingen and commercial partners Palaeo3D, is published in Acta Palaeontologica Polonica.

Dr Mark Young, of the University of Edinburgh's School of GeoSciences, who took part in the study, said: "The rock formations of southern Germany continue to give us fresh insights into the age of dinosaurs. These rock layers were deposited at a time when Europe was covered by a shallow sea, with countries such as Germany and the UK being a collection of islands."

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Ancient, four-legged whale with otter-like features found along the coast of Peru

This figure shows the bones of Peregocetus, including the mandible with teeth, scapula, vertebrae, sternum elements, pelvis, and fore- and hind limbs.

Cetaceans, the group including whales and dolphins, originated in south Asia more than 50 million years ago from a small, four-legged, hoofed ancestor. Now, researchers reporting the discovery of an ancient four-legged whale -- found in 42.6-million-year-old marine sediments along the coast of Peru -- have new insight into whales' evolution and their dispersal to other parts of the world. The findings are reported in the journal Current Biology on April 4.

The presence of small hooves at the tip of the whale's fingers and toes and its hip and limbs morphology all suggest that this whale could walk on land, according to the researchers. On the other hand, they say, anatomical features of the tail and feet, including long, likely webbed appendages, similar to an otter, indicate that it was a good swimmer too.

"This is the first indisputable record of a quadrupedal whale skeleton for the whole Pacific Ocean, probably the oldest for the Americas, and the most complete outside India and Pakistan," says Olivier Lambert of the Royal Belgian Institute of Natural Sciences.

Some years ago, study co-author Mario Urbina of Museo de Historia Natural-UNMSM, Peru, discovered a promising area for digging fossils in the coastal desert of southern Peru, named Playa Media Luna. In 2011, an international team, including members from Peru, France, Italy, the Netherlands, and Belgium, organized a field expedition, during which they excavated the remains of an ancient whale they've since named Peregocetus pacificus. It means "the traveling whale that reached the Pacific."

"When digging around the outcropping bones, we quickly realized that this was the skeleton of a quadrupedal whale, with both forelimbs and hind limbs," Lambert says.

With the help of microfossils, the sediment layers where the skeleton was positioned were precisely dated to the middle Eocene, 42.6 million years ago. Anatomical details of the skeleton allowed them to infer that the animal was capable of maneuvering its large body (up to 4 meters long, tail included), both on land and in the water. For instance, features of the caudal vertebrae (in the tail) are reminiscent of those of beavers and otters, suggesting a significant contribution of the tail during swimming.

The geological age of the new four-limbed whale and its presence along the western coast of South America strongly support the hypothesis that early cetaceans reached the New World across the South Atlantic, from the western coast of Africa to South America, the researchers report. The whales would have been assisted in their travel by westward surface currents and by the fact that, at the time, the distance between the two continents was half what it is today. The researchers suggest that, only after having reached South America, the amphibious whales migrated northward, finally reaching North America.

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Global warming disrupts recovery of coral reefs

The damage caused to the Great Barrier Reef by global warming has compromised the capacity of its corals to recover, according to new research published today in Nature.

"Dead corals don't make babies," said lead author Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University (JCU). "The number of new corals settling on the Great Barrier Reef declined by 89 percent following the unprecedented loss of adult corals from global warming in 2016 and 2017."

The unique study measured how many adult corals survived along the length of the world's largest reef system following extreme heat stress, and how many new corals they produced to replenish the Great Barrier Reef in 2018. The loss of adults resulted in a crash in coral replenishment compared to levels measured in previous years before mass coral bleaching.

"The number of coral larvae that are produced each year, and where they travel to before settling on a reef, are vital components of the resilience of the Great Barrier Reef. Our study shows that reef resilience is now severely compromised by global warming," said co-author Professor Andrew Baird.

"The biggest decline in replenishment, a 93% drop compared to previous years, occurred in the dominant branching and table coral, Acropora. As adults these corals provide most of the three-dimensional coral habitat that support thousands of other species," he said.

"The mix of baby coral species has shifted, and that in turn will affect the future mix of adults, as a slower than normal recovery unfolds over the next decade or longer."

"The decline in coral recruitment matches the extent of mortality of the adult brood stock in different parts of the Reef," added Professor Hughes. "Areas that lost the most corals had the greatest declines in replenishment."

"We expect coral recruitment will gradually recover over the next five to ten years, as surviving corals grow and more of them reach sexual maturity, assuming of course that we don't see another mass bleaching event in the coming decade," he said.

So far, the Great Barrier Reef has experienced four mass bleaching events due to global warming, in 1998, 2002, and back-to-back in 2016 and 2017. Scientists predict that the gap between pairs of coral bleaching events will continue to shrink as global warming intensifies.

"It's highly unlikely that we could escape a fifth or sixth event in the coming decade," said co-author Professor Morgan Pratchett.

"We used to think that the Great Barrier Reef was too big to fail -- until now," he said.

"For example, when one part was damaged by a cyclone, the surrounding reefs provided the larvae for recovery. But now, the scale of severe damage from heat extremes in 2016 and 2017 was nearly 1500km -- vastly larger than a cyclone track."

Professor Pratchett added that the southern reefs that escaped the bleaching are still in very good condition, but they are too far away to replenish reefs further north.

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A 5,000-year-old barley grain discovered in Finland changes understanding of livelihoods

Researchers determined the age of millennia-old barley grains using radiocarbon dating.

On the basis of prior research, representatives of the Pitted Ware Culture from the Stone Age have been known as hard-core sealers, or even Inuits of the Baltic Sea. Now, researchers have discovered barley and wheat grains in areas previously inhabited by this culture, leading to the conclusion that the Pitted Ware Culture adopted agriculture on a small scale.

A study carried out in cooperation with parties representing the discipline of archaeology and the Department of Chemistry at the University of Helsinki, as well as Swedish operators in the field of archaeology (The Archaeologists, a governmental consultant agency, and Arkeologikonsult, a business), found grains of barley and wheat in Pitted Ware settlements on Finland's Aland Islands and in the region of modern Stockholm.

The age of the grains was ascertained using radiocarbon dating. Based on the results, the grains originated in the period of the Pitted Ware culture, thus being approximately 4,300-5,300 years old. In addition to the cereal grains, the plant remnants found in the sites included hazelnut shells, apple seeds, tuberous roots of lesser celandine and rose hips.

The study suggests that small-scale farming was adopted by the Pitted Ware Culture by learning the trade from farmers of the Funnel Beaker Culture, the latter having expanded from continental Europe to Scandinavia.

Other archaeological artefacts are also evidence of close contact between these two cultures.

"The grains found on Aland are proof that the Pitted Ware Culture introduced cultivation to places where it had not yet been practised," says Santeri Vanhanen, a doctoral student of archaeology at the University of Helsinki.

Cereal perhaps used to brew beer?

The 5,000-year-old barley grain found on Aland is the oldest grain of cereal ever found in Finland. The researchers also found a handful of barley and wheat grains a few hundred years younger, representing either common wheat or club wheat.

"We also dated one barley grain found in Raseborg, southern Finland. This grain and the other earliest grains found in mainland Finland date back some 3,500 years, some 1,500 years behind Aland according to current knowledge," Vanhanen explains.

In prior studies, it has been extremely difficult to demonstrate that the hunter-gatherer population would have adopted farming during recorded history, let alone in the Stone Age. Research on ancient DNA has in recent years proven that the spread of agriculture in Europe was almost exclusively down to migrants.

"We find it possible that this population, which was primarily specialised in marine hunting, continued to grow plants as the practice provided the community with social significance."

From time to time, an abundance of pig bones are found at Pitted Ware sites, even though pigs were not an important part of their daily nourishment. For instance, the bones of more than 30 pigs were found in a grave located on the island of Gotland.

"Members of the Pitted Ware culture may have held ritual feasts where pigs and cereal products were consumed. It's not inconceivable that grains might even have been used to brew beer, but the evidence is yet to be found," Vanhanen continues.

Grain age determined through radiocarbon dating

The research relies primarily on archaeobotanical methodology, which helps examine plant remains preserved in archaeological sites. In this study, soil samples were collected from the sites, from which plant remains were extracted using a flotation method. The plant remains are charred; in other words, the grains and seeds have turned into carbon after having come to contact with fire.

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It's a one-way street for sound waves in this new technology

In the image, a flexible membrane (gray square) serves as an acoustic resonator, placed between two mirrors. When laser light is trapped between the mirrors, it passes repeatedly through the membrane. The force exerted by the laser light is used to control the membrane's vibrations.

Imagine being able to hear people whispering in the next room, while the raucous party in your own room is inaudible to the whisperers. Yale researchers have found a way to do just that -- make sound flow in one direction -- within a fundamental technology found in everything from cell phones to gravitational wave detectors.

What's more, the researchers have used the same idea to control the flow of heat in one direction. The discovery offers new possibilities for enhancing electronic devices that use acoustic resonators.

The findings, from the lab of Yale's Jack Harris, are published in the April 4 online edition of the journal Nature.

"This is an experiment in which we make a one-way route for sound waves," said Harris, a Yale physics professor and the study's principal investigator. "Specifically, we have two acoustic resonators. Sound stored in the first resonator can leak into the second, but not vice versa."

Harris said his team was able to achieve the result with a "tuning knob" -- a laser setting, actually -- that can weaken or strengthen a sound wave, depending on the sound wave's direction.

Then the researchers took their experiment to a different level. Because heat consists mostly of vibrations, they applied the same ideas to the flow of heat from one object to another.

"By using our one-way sound trick, we can make heat flow from point A to point B, or from B to A, regardless of which one is colder or hotter," Harris said. "This would be like dropping an ice cube into a glass of hot water and having the ice cubes get colder and colder while the water around them gets warmer and warmer. Then, by changing a single setting on our laser, heat is made to flow the usual way, and the ice cubes gradually warm and melt while the liquid water cools a bit. Though in our experiments it's not ice cubes and water that are exchanging heat, but rather two acoustic resonators."

Although some of the most basic examples of acoustic resonators are found in musical instruments or even automobile exhaust pipes, they're also found in a variety of electronics. They are used as sensors, filters, and transducers because of their compatibility with a wide range of materials, frequencies, and fabrication processes.

From Science Daily

VLA makes first direct image of key feature of powerful radio galaxies

Artist's conception of the dusty, doughnut-shaped object surrounding the supermassive black hole, disk of material orbiting the black hole, and jets of material ejected by the disk, at the center of a galaxy.

Astronomers used the National Science Foundation's Karl G. Jansky Very Large Array (VLA) to make the first direct image of a dusty, doughnut-shaped feature surrounding the supermassive black hole at the core of one of the most powerful radio galaxies in the Universe -- a feature first postulated by theorists nearly four decades ago as an essential part of such objects.

The scientists studied Cygnus A, a galaxy some 760 million light-years from Earth. The galaxy harbors a black hole 2.5 billion times more massive then the Sun at its core. As the black hole's powerful gravitational pull draws in surrounding material, it also propels superfast jets of material traveling outward at nearly the speed of light, producing spectacular "lobes" of bright radio emission.

Black hole-powered "central engines" producing bright emission at various wavelengths, and jets extending far beyond the galaxy are common to many galaxies, but show different properties when observed. Those differences led to a variety of names, such as quasars, blazars, or Seyfert galaxies. To explain the differences, theorists constructed a "unified model" with a common set of features that would show different properties depending on the angle from which they are viewed.

The unified model includes the central black hole, a rotating disk of infalling material surrounding the black hole, and the jets speeding outward from the poles of the disk. In addition, to explain why the same type of object looks different when viewed from different angles, a thick, dusty, doughnut-shaped "torus" is included, surrounding the inner parts. The torus obscures some features when viewed from the side, leading to apparent differences to the observer, even for intrinsically similar objects. Astronomers generically call this common set of features an active galactic nucleus (AGN).

"The torus is an essential part of the AGN phenomenon, and evidence exists for such structures in nearby AGN of lower luminosity, but we've never before directly seen one in such a brightly-emitting radio galaxy," said Chris Carilli, of the National Radio Astronomy Observatory (NRAO). "The torus helps explain why objects known by different names actually are the same thing, just observed from a different perspective," he added.

In the 1950s, astronomers discovered objects that strongly emitted radio waves, but appeared point-like, similar to distant stars, when later observed with visible-light telescopes. In 1963, Maarten Schmidt of Caltech discovered that one of these objects was extremely distant, and more such discoveries quickly followed. To explain how these objects, dubbed quasars, could be so bright, theorists suggested that they must be tapping the tremendous gravitational energy of supermassive black holes. The combination of black hole, the rotating disk, called an accretion disk, and the jets was termed the "central engine" responsible for the objects' prolific outpourings of energy.

The same type of central engine also appeared to explain the output of other types of objects, including radio galaxies, blazars, and Seyfert Galaxies. However, each showed a different set of properties. Theorists worked to develop a "unification scheme" to explain how the same thing could appear differently. In 1977, obscuration by dust was suggested as one element of that scheme. In a 1982 paper, Robert Antonucci, of the University of California, Santa Barbara, presented a drawing of an opaque torus -- a doughnut-shaped object -- surrounding the central engine. From that point on, an obscuring torus has been a common feature of astronomers' unified view of all types of active galactic nuclei.

"Cygnus A is the closest example of a powerful radio-emitting galaxy -- 10 times closer than any other with comparably bright radio emission. That proximity allowed us to find the torus in a high-resolution VLA image of the galaxy's core," said Rick Perley, also of NRAO. "Doing more work of this type on weaker and more distant objects will almost certainly need the order-of-magnitude improvement in sensitivity and resolution that the proposed Next Generation Very Large Array (ngVLA) would bring," he added.

The VLA observations directly revealed the gas in Cygnus A's torus, which has a radius of nearly 900 light-years. Longstanding models for the torus suggest that the dust is in clouds embedded in the somewhat-clumpy gas.

"It's really great to finally see direct evidence of something that we've long presumed should be there," Carilli said. "To more accurately determine the shape and composition of this torus, we need to do further observing. For example, the Atacama Large Millimeter/submillimeter Array (ALMA) can observe at the wavelengths that will directly reveal the dust," he added.

Carilli and Perley, with their colleagues Vivek Dhawan, also of NRAO, and Daniel Perley of Liverpool John Moores University in the UK, discovered the torus when following up their surprising discovery in 2016 of a new, bright object near the center of Cygnus A. That new object, they said, is most likely a second supermassive black hole that only recently encountered new material it could devour, causing it to produce bright emission the same way the central black hole does. The existence of the second black hole, they said, suggests that Cygnus A merged with another galaxy in the astronomically recent past.

Cygnus A, so named because it is the most powerful radio-emitting object in the constellation Cygnus, was discovered in 1946 by English physicist and radio astronomer J.S. Hey. It was matched to a visible-light, giant galaxy by Walter Baade and Rudolf Minkowski in 1951. It became an early target for the VLA soon after its completion in the early 1980s. Detailed VLA images of Cygnus A published in 1984 produced major advances in astronomers' understanding of such galaxies.

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Rise of religion pre-dates Incas at Lake Titicaca

Findings, such as this bowl, allowed the researchers to reconstruct the structure and significance of repeated state rituals by the Tiwanaku people.

An ancient group of people made ritual offerings to supernatural deities near the Island of the Sun in Lake Titicaca, Bolivia, about 500 years earlier than the Incas, according to an international team of researchers. The team's findings suggest that organized religion emerged much earlier in the region than previously thought.

"People often associate the Island of the Sun with the Incas because it was an important pilgrimage location for them and because they left behind numerous ceremonial buildings and offerings on and around this island," said Jose Capriles, assistant professor of anthropology, Penn State. "Our research shows that the Tiwanaku people, who developed in Lake Titicaca between 500 and 1,100 AD, were the first people to offer items of value to religious deities in the area."

The Incas, Capriles noted, did not arrive in the Lake Titicaca region until around the 15th century AD.

A team lead by Christophe Delaere, postdoctoral fellow at the University of Oxford Centre for Maritime Archaeology and research associate at the Universite Libre de Bruxelles, conducted underwater archaeological excavations in the Khoa Reef near the Island of the Sun. The archaeologists used sonar and underwater three-dimensional photogrammetry to scan and map the reef. They used a water-dredge to excavate the sediment and measured and weighed all the archaeological materials they uncovered. Their results appear today (April 1) in Proceedings of the National Academy of Sciences.

In particular, the team found ritual offerings consisting of ceramic feline incense burners; sacrificed juvenile llamas; and gold, shell and stone ornaments.

"The findings, and especially the ceramic puma-shaped incense burners, are significant because they help us gain a broader understanding of the ritual behavior and religion of the Tiwanaku state -- a society that preceded the Incas by several hundred years," said Delaere.

The puma was an important religious symbol to the Tiwanaku, Delaere added.

Another observation made by the team was that the religious offerings appear to have been made intentionally to be submerged underwater.

"The presence of anchors near the offerings suggests that officiating authorities may have deposited the offerings during rituals held from boats," said Capriles.

According to Capriles, the Island of the Sun was likely important to the Tiwanaku people because of its natural beauty, but also because of its location at the center of the Andes Mountains.

"It was a strategic and ritually charged place," said Capriles. "At the Island of the Sun and the Khoa Reef, religious specialists could come together for sacred ceremonies. The ritual offerings they made here demonstrate the transitioning of societies from more local-based religious systems to something that had a more ambitious geopolitical and spiritual appeal."

In turn, he added, this emergence of organized religion likely led to consolidation of the groups of people living around the lake and the emergence of the Tiwanaku state, characterized by political hierarchy.

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Building blocks of DNA and RNA could have appeared together before life began on Earth

Did RNA and DNA arise at around the same time in the first life forms?

Scientists for the first time have found strong evidence that RNA and DNA could have arisen from the same set of precursor molecules even before life evolved on Earth about four billion years ago.

The discovery, published April 1 in Nature Chemistry, suggests that the first living things on Earth may have used both RNA and DNA, as all cell-based life forms do now. In contrast, the prevailing scientific view -- the "RNA World" hypothesis -- is that early life forms were based purely on RNA, and only later evolved to make and use DNA.

"These new findings suggest that it may not be reasonable for chemists to be so heavily guided by the RNA World hypothesis in investigating the origins of life on Earth," says co-principal investigator Ramanarayanan Krishnamurthy, PhD, associate professor of chemistry at Scripps Research.

Krishnamurthy and his lab worked on the study with the lab of John Sutherland, DPhil, of the UK Medical Research Council's Laboratory of Molecular Biology at Cambridge, as part of the New York-based Simons Foundation's Collaboration on the Origins of Life.

RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) are chemically very similar, but chemists have never been able to show how the one could have been converted to the other on the early Earth, except with the help of enzymes produced by early organisms. Due in part to this lack of a demonstrated pre-life or "pre-biotic" chemical path connecting RNA to DNA, researchers in this field have been inclined to think that the simpler, more versatile one, RNA, was the basis for the first life forms -- or at least for an early stage of life prior to the emergence of DNA. RNA is able to store genetic information as DNA can, is able to catalyze biochemical reactions as protein enzymes can, and otherwise probably could have performed the basic biological tasks that would have been necessary in the first life forms.

Although origin-of-life researchers in recent decades have largely come to embrace the RNA World hypothesis, Sutherland, Krishnamurthy, Harvard's Jack Szostak and others have accumulated evidence that RNA and DNA may have arisen more or less all at once in the first life forms.

In a study published in 2017 for example, Krishnamurthy and colleagues at Scripps Research identified a compound that plausibly was present on the pre-biotic Earth and could have performed the crucial task of linking RNA building blocks into larger, chain-like RNA strands -- and could have done the same for the building blocks of DNA and proteins.

In the new study, the scientists combined insights from that investigation with recent findings from Sutherland and his lab on a compound called thiouridine. The latter was likely present on Earth before life arose, and could have been a chemical precursor of the nucleoside building blocks of early RNAs. The team showed that in a few chemical-reaction steps, which plausibly could have occurred in a pre-biotic world, they could convert this precursor of an RNA building-block into a DNA building block -- deoxyadenosine, which forms the letter "A" in the modern, four-letter DNA code. Alternatively they could convert thiouridine into deoxyribose, which is very closely related to deoxyadenosine and may also have been a precursor of early DNA building blocks.

The finding should make it easier for scientists to accept the possibility that DNA and RNA arose together and were included in the first life forms. Some researchers including Sutherland have suggested that RNA and DNA might even have been mixed together to make the first genes. No such organism is known to occur naturally now, but a recent paper by Scripps Research's Peter Schultz, PhD and colleagues described an engineered bacterium that can survive with genes made of an RNA/DNA mix.

Krishnamurthy suspects that, however life arose, RNA and DNA with their respective strengths and shortcomings would swiftly have sorted themselves into the rather strict division of labor seen in all cells today: DNA for the stable long-term storage of genetic information, and RNA for its own special set of tasks including the short-term storage and transport of genetic information and the making of proteins.

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Researchers tap rare pristine air to reveal pollution's impact

Data was collected by a research aircraft zigzagging between pristine air over the Amazon rainforest and polluted air nearby.

Five years ago, researchers spent three hours packed aboard a steamy Gulfstream-1 research aircraft as it zig-zagged between pristine air over the Amazon rainforest and polluted air nearby. It was like a trip back (and forth) through time, as scientists weaved between the two vastly different settings, snagging air samples characteristic of today's industrial environment as well as samples of unpolluted air, like that before the industrial age.

An international team of scientists led by Manish Shrivastava of the U.S. Department of Energy's Pacific Northwest National Laboratory has analyzed some of the data and found that human-caused pollution spurs the production of climate-changing particles known as secondary organic aerosols much more than previously thought. The team published its results in Nature Communications.

The findings illustrate how pollution from cars, power plants and other sources combines with natural emissions from trees in the Amazon to spur a marked increase in tiny particles that can reflect or absorb sunlight, help create clouds, change rainfall patterns, and determine how carbon flows between the land and atmosphere -- all with dramatic effects on our planet.

The result comes from a research campaign, known as GOAmazon, led by the Atmospheric Radiation Measurement Research Facility, a Department of Energy Office of Science user facility. The campaign focused on the region near and around Manaus, a Brazilian city of more than 2 million people that is surrounded by tropical forests for hundreds of miles. Scientists refer to the vast forest canopy around Manaus as a "Green Ocean," giving the campaign's name its first letters.

The region offers a research environment hard to find anywhere else on earth. On one side of an undefined boundary is a straight-up tropical rainforest with crystal-clear air and levels of 300 aerosol particles per cubic centimeter; on the other side is the air over Manaus, with particle concentrations 100 times higher due to human activity.

"To really understand how pollution has influenced the atmosphere, we need to compare today's atmosphere with times before the industrial age," said Shrivastava. "This is challenging; of course, we cannot go back in time. But the Amazon is one of the few places on earth where we can study atmospheric chemistry both past and present simultaneously."

On that sunny day five years ago, the ARM aircraft ambled from one side of the boundary to the other, flying about the length of a football field every second, taking air samples from the pristine and then the polluted.

"The region provides a wonderful natural laboratory to understand how anthropogenic emissions have an impact on atmospheric chemistry and climate," said Shrivastava.

While only a tiny sliver of our planet provides the unique opportunity for this study, the findings apply to atmospheric chemistry that takes place everywhere on earth every moment.

This chemistry is behind the refreshing scents of a forest meadow or fresh flowers. When those scents hit our olfactory nerve, we're actually sensing an array of gases, such as carbon-containing isoprene and terpenes, which are given off naturally by trees and other vegetation. The gases contribute to ozone and other forms of haze that affect the amount of sunlight reaching the earth.

When these natural carbon emissions interact in sunlight with nitrogen oxide -- naturally emitted from soils but also a common product largely emitted by human activity -- one result is the formation of tiny particles known as secondary organic aerosols. Though aerosols are tiny, much smaller than the width of a human hair, they are no bit players when it comes to earth's climate. They're an important component in the planet's energy and carbon cycles, determining in part the fate of the planet's vast reservoir of carbon and how it flows between the land and the atmosphere.

Shrivastava and colleagues sought to learn how anthropogenic emissions increase the production of these naturally occurring carbon particles -- just how extensive the effects of human activity are in spurring the transformation of gases ejected from vegetation to these powerful climate-changing particles.

The team integrated this data with other laboratory measurements to develop an advanced computer model to simulate chemical reactions that form particles in the atmosphere. The model does double duty, reproducing both pre-industrial and present-day chemistry. Most models have largely been created based on present-day conditions; the Amazon measurements provide information about pre-industrial chemistry conditions that improved the model's predictive abilities.

The team found that nitrogen oxide emitted from human activities like traffic and oil refineries promotes the creation of these particles from natural forest carbon much more than previously thought, causing an average increase of anywhere from 60 to 200 percent and even up to 400 percent in some cases. That's compared to the 20 percent previously estimated by scientists based on data in more polluted continental locations.

The team also showed that most of these secondary carbon-containing particles were formed by this phenomenon.

"The impact of pollution in creating secondary organic aerosols has been very difficult to tease out," says Shrivastava. "Our findings indicate the earth's atmosphere in many continental locations has already been substantially altered by human activities, and there's a much larger and widespread impact than has been appreciated."

In their paper, Shrivastava and the other authors conclude: "Our results provide a clear picture of how anthropogenic emissions are likely to have greatly modified biogenic SOA [secondary organic aerosol] formation since preindustrial times over the Earth, and imply that rapid urbanization in future years might substantially enhance biogenic SOA formation in the pristine forested regions of the Amazon."

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Dark matter is not made up of tiny black holes

The Milky Way galaxy (left) and the Andromeda galaxy (right) are separated by 2.6 million light years. Compared with the areas where stars are clustered together, dark matter is believed to be distributed over a much larger volume.

An international team of researchers has put a theory speculated by the late Stephen Hawking to its most rigorous test to date, and their results have ruled out the possibility that primordial black holes smaller than a tenth of a millimeter make up most of dark matter. Details of their study have been published in this week's Nature Astronomy.

Scientists know that 85 per cent of the matter in the Universe is made up of dark matter. Its gravitational force prevents stars in our Milky Way from flying apart. However, attempts to detect such dark matter particles using underground experiments, or accelerator experiments including the world's largest accelerator, the Large Hadron Collider, have failed so far.

This has led scientists to consider Hawking's 1974 theory of the existence of primordial black holes, born shortly after the Big Bang, and his speculation that they could make up a large fraction of the elusive dark matter scientists are trying to discover today.

An international team of researchers, led by Kavli Institute for the Physics and Mathematics of the Universe Principal Investigator Masahiro Takada, PhD candidate student Hiroko Niikura, Professor Naoki Yasuda, and including researchers from Japan, India and the US, have used the gravitational lensing effect to look for primordial black holes between Earth and the Andromeda galaxy. Gravitational lensing, an effect first suggested by Albert Einstein, manifests itself as the bending of light rays coming from a distant object such as a star due to the gravitational effect of an intervening massive object such as a primordial black hole. In extreme cases, such light bending causes the background star to appear much brighter than it originally is.

However, gravitational lensing effects are very rare events because it requires a star in the Andromeda galaxy, a primordial black hole acting as the gravitational lens, and an observer on Earth to be exactly in line with one another. So to maximize the chances of capturing an event, the researchers used the Hyper Suprime-Cam digital camera on the Subaru telescope in Hawaii, which can capture the whole image of the Andromeda galaxy in one shot. Taking into account how fast primordial black holes are expected to move in interstellar space, the team took multiple images to be able to catch the flicker of a star as it brightens for a period of a few minutes to hours due to gravitational lensing.

From 190 consecutive images of the Andromeda galaxy taken over seven hours during one clear night, the team scoured the data for potential gravitational lensing events. If dark matter consists of primordial black holes of a given mass, in this case masses lighter than the moon, the researchers expected to find about 1000 events. But after careful analyses, they could only identify one case. The team's results showed primordial black holes can contribute no more than 0.1 per cent of all dark matter mass. Therefore, it is unlikely the theory is true.

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'Molecular surgery' reshapes living tissue with electricity but no incisions

A new noninvasive process can alter the curve of a cornea from that seen in blue in a) to the new position seen in red in b) to fix vision problems.

Traditional surgery to reshape a nose or ear entails cutting and suturing, sometimes followed by long recovery times and scars. But now, researchers have developed a "molecular surgery" process that uses tiny needles, electric current and 3D-printed molds to quickly reshape living tissue with no incisions, scarring or recovery time. The technique even shows promise as a way to fix immobile joints or as a noninvasive alternative to laser eye surgery.

The researchers will present their results today at the American Chemical Society (ACS) Spring 2019 National Meeting & Exposition.

"We envision this new technique as a low-cost office procedure done under local anesthesia," says Michael Hill, Ph.D., one of the project's principal investigators, who will discuss the work at the meeting. "The whole process would take about five minutes."

Hill, who is at Occidental College, became involved in this project when Brian Wong, M.D., Ph.D., who is at the University of California, Irvine, asked for help in developing a noninvasive technique to reshape cartilage. Such a method would be useful for cosmetic surgery procedures, such as making a nose more attractive. But the method also could help fix problems, such as a deviated septum, or conditions for which no good treatments exist, such as joint contractures caused by stroke or cerebral palsy. Having suffered through painful deviated septum surgery himself, Hill understands what patients go through, and was excited to join a project to develop a better strategy.

Wong was already an expert in one alternative technique that uses an infrared laser to heat cartilage, making it flexible enough to reshape. "The problem is, that technique is expensive, and it's hard to heat the cartilage enough so that it's malleable without killing the tissue," Hill says. To find a more practical approach, Wong's team began experimenting with passing current through cartilage to heat it up. The method indeed allowed them to reshape tissue, but, curiously, not by warming it. Wong turned to Hill to determine just how the new method was working and to refine it to prevent tissue damage.

Cartilage is made up of tiny rigid fibers of collagen loosely woven together by biopolymers. Its structure resembles spaghetti that's been randomly dumped on a counter, with the individual strands tied together with thread. "If you picked it up, the strands wouldn't fall apart, but it would be floppy," Hill says. Cartilage also contains negatively charged proteins and positively charged sodium ions. Cartilage with a greater density of these charged particles is stiffer than cartilage with a lower charge density.

Hill's group discovered that passing current through cartilage electrolyzes water in the tissue, converting the water into oxygen and hydrogen ions, or protons. The positive charge of the protons cancels out the negative charge on the proteins, reducing charge density and making the cartilage more malleable. "Once the tissue is floppy," he says, "you can mold it to whatever shape you want."

The team tested the method on a rabbit whose ears normally stand upright. They used a mold to hold one ear bent over in the desired new shape. If they had then removed the mold without applying a current, the rabbit's ear would have sprung back into its original upright position, just like a human ear would. But by inserting microneedle electrodes into the ear at the bend and pulsing current through them with the mold in place, they briefly softened the cartilage at the bend site without damage. Turning off the current then allowed the cartilage to harden in its new shape, after which the mold was removed.

To achieve this outcome with traditional methods, a surgeon would have to cut through the skin and cartilage and then stick the pieces back together. That can lead to formation of scar tissue at the joint. That scar tissue must sometimes be removed in subsequent operations, Hill says. By avoiding this mechanical damage to the cartilage, the molecular surgery technique causes no scarring and no pain.

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Researchers find ancient Maya farms in Mexican wetlands

UC assistant professor Christopher Carr examines an ancient quarry in Yaxnohcah, Mexico.

Archaeologists with the University of Cincinnati used the latest technology to find evidence suggesting ancient Maya people grew surplus crops to support an active trade with neighbors up and down the Yucatan Peninsula.

They will present their findings at the annual American Association of Geographers conference in Washington, D.C.

The Mayan civilization stretched across portions of Mesoamerica, a region spanning Mexico and Central America. The oldest evidence of Maya civilization dates back to 1800 B.C., but most cities flourished between 250 and 900 A.D. By the time Spanish ships arrived in the 1500s, some of the biggest cities were deserted. Researchers at UC are trying to piece together the life history of the Maya before the Spanish conquest.

Nicholas Dunning, a professor of geography in UC's McMicken College of Arts and Sciences, was part of a research team that found evidence of cultivation along irregular-shaped fields in Mexico that followed the paths of canals and natural water channels at a place called Laguna de Terminos on the Gulf of Mexico. The archaeologists expect to find evidence of habitation when they begin excavations.

The extensive croplands suggest the ancient Maya could grow surplus crops, especially the cotton responsible for the renowned textiles that were traded throughout Mesoamerica.

"It was a much more complex market economy than the Maya are often given credit for," Dunning said.

Local workers brought the Laguna de Terminos site to the attention of researchers about seven years ago.

"A forester working in the area said there seemed to be a network of ancient fields," Dunning said. "I looked on Google Earth and was like, 'Whoa!' It was an area in the Maya Lowlands that I'd never paid any attention to. And obviously not a lot of other people had, either, from the perspective of looking at ancient agriculture."

Satellite images revealed a patchwork quilt of blocks along drainage ditches that suggested they were built. Archaeologist also studied imagery NASA created of the region using a tool called Light Detection and Ranging, or LIDAR, that can depict the contours of the ground beneath the leafy canopy of trees and vegetation. Their review confirmed Dunning's suspicions: the area was covered in ancient farm fields.

"It appears they developed fairly simply from modifications of existing drainage along the eastern edge of the wetlands," Dunning said. "They probably deepened and straightened some channels or connected them in places, but then further expanded the fields with more sophisticated hydro-engineering."

LIDAR gives scientists a never-before-seen picture of the Earth's surface even after centuries of unchecked jungle growth conceals the remains of ancient structures. Researchers look for telltale signs of human activity: squares and rectangles indicating old foundations and circular pits from human-made reservoirs and quarries where the chert used in stone tools was mined. On the LIDAR maps, any hidden structures pop out, including ancient roads and former villages.

"That's the magic of LIDAR," UC assistant research professor Christopher Carr said.??Carr spent a career practicing engineering before returning to UC to study and eventually teach in the geography department. He approaches questions about the ancient Maya from an engineer's perspective.

Carr pointed to a map of Yaxnohcah, Mexico, showing a small reservoir the ancient Maya apparently dug in a wetland far from cultivated fields or known settlements.

"What were my ancient counterparts thinking when they built that water reservoir? What did they want to accomplish?" he asked.

Carr also used the LIDAR imagery in the project to follow an ancient Maya road that perhaps hasn't been traveled in more than 1,000 years. The road is perfectly visible on the LIDAR map but is virtually impossible to discern when you are standing right on it, Carr said.

"There's vegetation everywhere. But when you've been doing this for a while, you notice little things," Carr said. "I'll have a LIDAR image on my smartphone that shows me where I am, but I don't see anything but rainforest. You just walk back and forth until you can feel something underfoot and follow it."

Identifying possible roads is important for another interest of the UC researchers: ancient Maya marketplaces. Dunning and Carr are working at Yaxnohcah with researchers such as Kathryn Reese-Taylor from the University of Calgary and Armando Anaya Hernandez from Universidad Autónoma de Campeche to unlock the mysteries of the ancient Maya economy. Additionally, they and graduate student Thomas Ruhl have been analyzing NASA's LIDAR imagery across the Yucatan Peninsula to identify more ancient marketplaces.

Unlike pyramids or even many homes, marketplaces had no foundations or permanent structures, researchers said. They were built on low platforms or cleared areas, perhaps like a seasonal fair or flea market. But they were an important part of life in Maya culture

Dunning said the presence of roads between Maya cities would lend credence to the value the ancient Maya placed on trade with their neighbors. He thinks some of the larger squares identified on the LIDAR maps represent these open markets.

"In some areas, they have this very distinct physical signature," Dunning said. "So far, we've identified several possible marketplaces. We don't know for sure that they're marketplaces, but they have an architectural layout that is suggestive of one."

Soil analysis at other locations identified evidence of ancient butcher shops and stone masons. Dunning solicited the help of UC's botanists who are conducting analyses that might shed light on his marketplace hypothesis. But the LIDAR maps themselves are instructive.

"I look at spatial patterns. If you look at these big structures and small pyramids, you can tell they're important structures," Carr said. "And then you have this 'lightweight' thing next to it. That's what a marketplace looks like to me."

Dunning said the ancient Maya likely sold perishable goods such as maize and a starchy tuber called manioc. And they traded "mantas," or bolts of the ornate and richly patterned textiles made from the cotton they grew. These were prized by the Spaniards who arrived in the 1600s.

"We don't have direct evidence of what the textiles look like in this area. But if you look at ancient paintings and sculptures, people were wearing very elaborate garments," Dunning said.

Dunning first explored the historic sites of the Yucatan Peninsula at age 14 when he and his older brother drove down to Mexico from Illinois.

"We took a train to the Yucatan and used public transportation to get around to the sites," Dunning said.

He applied to the University of Chicago partly because it offered a Mayan language class. Dunning returned to Mexico while in college to conduct his first field research. He's been back many times since.

"My interest in archaeology is in human-environment interactions, including agriculture," Dunning said.

Dunning is learning more about how ancient Maya people shaped their world to overcome challenges and take advantage of natural opportunities. Dunning's work also took him to a place called Acalan near the Gulf of Mexico.

"Roughly translated, Acalan means 'place of canoes' because it's very watery," Dunning said. "And getting around by water is far easier than any other means in that area."

Then as now the region is covered in thick tropical rainforest. Researchers have to be wary of cheeky monkeys that will throw fruit or worse from the treetops. Carr said one encounter left him sore for days.

"There was this aggressive spider monkey. He'd seen me a couple days earlier. And he's back shaking the trees," Carr said. "And all of a sudden, I'm lying flat on the ground. A branch hit me in the shoulder and knocked me to the ground."

Visiting archaeologists at Yaxnohcah stay at a former Army outpost that was converted into a staffed research station.

"Living conditions are actually luxurious by camping standards. You're in the field all day and you're dirty and tired. But you can take a shower. And when you're finished, someone has cooked you a meal," Carr said.

At Laguna de Terminos, UC researchers are working to collect clues about the ancient Maya before they are lost to development. Many of the wetlands are being drained or plowed up for grazing pasture.?

Dunning said ironically these low-yield pastures provide far less economic value to today's farmers than the seeming bounty of crops the ancient Maya derived from them more than 1,000 years ago. Their study warns the land-use practices are causing environmental damage to some of these valuable wetlands.

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