May 20, 2017
With this discovery, most of the known dwarf planets in the Kuiper Belt larger than 600 miles across have companions. These bodies provide insight into how moons formed in the young solar system.
"The discovery of satellites around all of the known large dwarf planets -- except for Sedna -- means that at the time these bodies formed billions of years ago, collisions must have been more frequent, and that's a constraint on the formation models," said Csaba Kiss of the Konkoly Observatory in Budapest, Hungary. He is the lead author of the science paper announcing the moon's discovery. "If there were frequent collisions, then it was quite easy to form these satellites."
The objects most likely slammed into each other more often because they inhabited a crowded region. "There must have been a fairly high density of objects, and some of them were massive bodies that were perturbing the orbits of smaller bodies," said team member John Stansberry of the Space Telescope Science Institute in Baltimore, Maryland. "This gravitational stirring may have nudged the bodies out of their orbits and increased their relative velocities, which may have resulted in collisions."
But the speed of the colliding objects could not have been too fast or too slow, according to the astronomers. If the impact velocity was too fast, the smash-up would have created lots of debris that could have escaped from the system; too slow and the collision would have produced only an impact crater.
Collisions in the asteroid belt, for example, are destructive because objects are traveling fast when they smash together. The asteroid belt is a region of rocky debris between the orbits of Mars and the gas giant Jupiter. Jupiter's powerful gravity speeds up the orbits of asteroids, generating violent impacts.
The team uncovered the moon in archival images of 2007 OR10 taken by Hubble's Wide Field Camera 3. Observations taken of the dwarf planet by NASA's Kepler Space Telescope first tipped off the astronomers of the possibility of a moon circling it. Kepler revealed that 2007 OR10 has a slow rotation period of 45 hours. "Typical rotation periods for Kuiper Belt Objects are under 24 hours," Kiss said. "We looked in the Hubble archive because the slower rotation period could have been caused by the gravitational tug of a moon. The initial investigator missed the moon in the Hubble images because it is very faint."
The astronomers spotted the moon in two separate Hubble observations spaced a year apart. The images show that the moon is gravitationally bound to 2007 OR10 because it moves with the dwarf planet, as seen against a background of stars. However, the two observations did not provide enough information for the astronomers to determine an orbit.
"Ironically, because we don't know the orbit, the link between the satellite and the slow rotation rate is unclear," Stansberry said.
The astronomers calculated the diameters of both objects based on observations in far-infrared light by the Herschel Space Observatory, which measured the thermal emission of the distant worlds. The dwarf planet is about 950 miles across, and the moon is estimated to be 150 miles to 250 miles in diameter. 2007 OR10, like Pluto, follows an eccentric orbit, but it is currently three times farther than Pluto is from the sun.
Read more at Science Daily
The area south of the Pyrenees is particularly suitable for studying sedimentary layers. Rocks are exposed over large distances, allowing researchers to undertake direct observation. Turbidites can be seen here: large sediment deposits formed in the past by underwater avalanches consisting of sand and gravel. "We noticed that these turbidites returned periodically, about every million years. We then wondered what the reasons for this cyclicity were," explains Sébastien Castelltort, professor in the department of earth sciences in UNIGE's faculty of sciences.
The ups and downs of oceans regulate sedimentation cycles
The geologists focused their attention on Eocene sedimentary rocks (about 50 million years ago), which was particularly hot, and undertook the isotopic profiling of the sedimentary layers. "We took a sample every 10 metres," says Louis Honegger, a researcher at UNIGE, "measuring the ratio between 13C (heavy carbon stable isotope) and 12C (light carbon stable isotope). The ratio between the two tells us about the amount of organic matter, the main consumer of 12C, which is greater when the sea level is high. The variations in the ratio helped us explore the possible link with the sea level." The research team found that the turbidite-rich intervals were associated with high 12C levels, and almost always corresponded to periods when the sea level was low. It seems that sedimentary cycles are mainly caused by the rise and fall of the sea level and not by the episodic growth of mountains.
When the sea level is high, continental margins are flooded under a layer of shallow water. Since the rivers are no longer able to flow, they begin to deposit the sediments they carry there. This is why so little material reaches the deep basins downstream. When the sea level is low, however, rivers erode their beds to lower the elevation of their mouth; they transfer their sediment directly to the continental slopes of the deep basins, creating an avalanche of sand and gravel. Consequently, if the variations of the sea level are known, it is possible to predict the presence of large sedimentary accumulations created by turbidites, which often contain large volumes of hydrocarbons, one of the holy grails of exploration geology.
Read more at Science Daily
A puree made from these peppers — which are infamous for their off-the-charts level of spiciness — led to a rare, life-threatening condition in an otherwise healthy, 47-year-old man in California, according to a recent report of the man's case.
Ghost peppers are among the hottest chili peppers in the world, the report said. They have a measured "heat" of more than 1 million Scoville heat units, according to the report. (For comparison, a poblano pepper measures at 2,000 Scoville units, and jalapeños come in at 5,000. Eating a single seed from a ghost pepper can cause severe burning in the mouth that lasts up to 30 minutes, the report said.
In the man's case, a ghost pepper had been pureed and served atop a hamburger as a part of an eating contest at local restaurant. After finishing the pepper-topped burger, the man drank six large glasses of water, then began "violently retching and vomiting," according to the report, which was published online in September in the Journal of Emergency Medicine.
The man ended up going to the emergency room in San Francisco because he couldn't stop vomiting, and developed severe chest and stomach pain, the authors wrote.
A CT scan of the man's chest appeared to show that his esophagus was torn and that his left lung had collapsed, so the man was sent for emergency surgery.
During the operation, the surgeons found a 2.5-centimeter (1 inch) tear in the man's esophagus. The tear was leaking food — a mix of "hamburger, onions and other green vomitus material" — into the space around the man's left lung, which had collapsed, according to the report. The surgeons repaired the man's esophagus and re-inflated his lung, then placed him on a feeding tube so that his esophagus could heal.
The man's condition, a "spontaneous esophageal rupture," which is also called Boerhaave syndrome, is "a relatively rare phenomenon," said lead study author Dr. Ann Arens, who was a physician in the department of emergency medicine at the University of California, San Francisco at the time of the man's case in the summer of 2015. (Arens is currently an emergency medicine doctor and medical toxicologist at Hennepin County Medical Center in Minneapolis.)
Spontaneous esophageal rupture is caused by violent vomiting and retching, Arens said. In other words, the man's reaction to the ghost pepper, rather than the pepper itself, caused the rupture, Arens said.
The condition is very dangerous, and is fatal in 20 to 40 percent of all cases, even when patients receive treatment, the report said. "If [the condition is] left untreated, mortality approaches 100 percent," the authors wrote.
When patients die from a ruptured esophagus, the cause of death is likely a "rapid and fatal infection," Arens told Live Science.
The man was sent home from the hospital 23 days after the operation, the report said. His feeding tube was still in place when he was sent home, but Arens said the tube was only temporary, until the esophagus healed. She said she believes the man is currently doing well.
When Arens spoke to the man after the surgery, he "did not seem keen to try [eating a ghost pepper] again," she said.
Read more at Discovery News
May 18, 2017
|While showing monkeys videos of social interaction, scientists scanned their brains and tracked their gaze (red dot).|
Working with rhesus macaque monkeys, researchers in Winrich Freiwald's Laboratory of Neural Systems at The Rockefeller University have discovered tantalizing clues about the origins of our ability to understand what other people are thinking. As reported in Science on May 18, Freiwald and postdoc Julia Sliwa have identified areas in the brains of these primates that are exclusively dedicated to analyzing social interactions. And they may have evolved into the neural circuitry that supports theory of mind in the human brain.
The team used functional magnetic resonance imaging (fMRI) to identify those parts of the monkeys' brains that become active when the animals watched different kinds of videos.
Some of those videos showed inanimate objects (i.e., monkey toys) colliding or otherwise interacting physically. Others showed macaques interacting with the same objects by playing with them. And others still showed macaques interacting socially with other macaques: grooming, playing, fighting, etc.
By analyzing the fMRI data, the researchers were able to determine precisely which portions of the monkeys' brains responded to physical or social interactions. And much of what they found came as a surprise.
Monkey see, monkey analyze
For example, the team expected that areas containing specialized brain cells called mirror neurons, which fire when an animal performs an action such as grasping a stick or hitting a ball, or sees another animal performing the same action, would light up when the macaques watched other macaques playing with toys.
But the macaques' mirror neuron regions also showed activity when the animals watched their fellow monkeys interacting socially -- and even when they watched objects colliding with other objects.
That, says Sliwa, suggests that the motor neuron system, which also exists in the human brain, could be more involved than previously thought in understanding a variety of both social and non-social interactions.
The scientists also expected those areas of the brain that respond selectively to specific visual shapes -- namely, faces, bodies, or objects -- would be activated when the monkeys watched videos featuring those shapes. And that did indeed happen.
Surprisingly, though, the body-selective areas of the macaques' brains got an extra boost when the animals watched videos of monkeys interacting with objects. And their face-selective areas perked up even more in response to videos of monkey-on-monkey social interactions. This suggests that the same parts of the brain that are responsible for analyzing visual shapes might also be partly responsible for analyzing both physical and social interactions.
An exclusive social network
Most intriguingly, the team discovered that additional areas of the brain, far removed from those face- and body-selective areas, also lit up in response to social interactions. Digging deeper, the researchers even identified a portion of the network that responded exclusively to social interactions, remaining nearly silent in their absence.
"That was both unexpected and mind-boggling," says Freiwald, who explains that no other study has shown evidence of a network in the brain going dark when denied its preferred input.
This socially sensitive network is located in the same areas of the brain that are associated with theory of mind in humans -- areas that are similarly activated only when we reflect on the thoughts of others.
Read more at Science Daily
Earlier ALMA observations of Fomalhaut -- taken in 2012 when the telescope was still under construction -- revealed only about one half of the debris disk. Though this first image was merely a test of ALMA's initial capabilities, it nonetheless provided tantalizing hints about the nature and possible origin of the disk.
The new ALMA observations offer a stunningly complete view of this glowing band of debris and also suggest that there are chemical similarities between its icy contents and comets in our own solar system.
"ALMA has given us this staggeringly clear image of a fully formed debris disk," said Meredith MacGregor, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author on one of two papers accepted for publication in the Astrophysical Journal describing these observations. "We can finally see the well-defined shape of the disk, which may tell us a great deal about the underlying planetary system responsible for its highly distinctive appearance."
Fomalhaut is a relatively nearby star system and one of only about 20 in which planets have been imaged directly. The entire system is approximately 440 million years old, or about one-tenth the age of our solar system.
As revealed in the new ALMA image, a brilliant band of icy dust about 2 billion kilometers wide has formed approximately 20 billion kilometers from the star.
Debris disks are common features around young stars and represent a very dynamic and chaotic period in the history of a solar system. Astronomers believe they are formed by the ongoing collisions of comets and other planetesimals in the outer reaches of a recently formed planetary system. The leftover debris from these collisions absorbs light from its central star and reradiates that energy as a faint millimeter-wavelength glow that can be studied with ALMA.
Using the new ALMA data and detailed computer modeling, the researchers were able to calculate the precise location, width, and geometry of the disk. These parameters confirm that such a narrow ring is likely produced through the gravitational influence of planets in the system, noted MacGregor.
The new ALMA observations are also the first to definitively show "apocenter glow," a phenomenon predicted in a 2016 paper by Margaret Pan, a scientist at the Massachusetts Institute of Technology in Cambridge, who is also a co-author on the new ALMA papers. Like all objects with elongated orbits, the dusty material in the Fomalhaut disk travels more slowly when it is farthest from the star. As the dust slows down, it piles up, forming denser concentrations in the more distant portions of the disk. These dense regions can be seen by ALMA as brighter millimeter-wavelength emission.
Using the same ALMA dataset, but focusing on distinct millimeter-wavelength signals naturally emitted by molecules in space, the researchers also detected vast stores of carbon monoxide gas in precisely the same location as the debris disk.
"These data allowed us to determine that the relative abundance of carbon monoxide plus carbon dioxide around Fomalhaut is about the same as found in comets in our own solar system," said Luca Matrà with the University of Cambridge, UK, and lead author on the team's second paper. "This chemical kinship may indicate a similarity in comet formation conditions between the outer reaches of this planetary system and our own." Matrà and his colleagues believe this gas is either released from continuous comet collisions or the result of a single, large impact between supercomets hundreds of times more massive than Hale-Bopp.
The presence of this well-defined debris disk around Fomalhaut, along with its curiously familiar chemistry, may indicate that this system is undergoing its own version of the Late Heavy Bombardment, a period approximately 4 billion years ago when Earth and other planets were routinely struck by swarms of asteroids and comets left over from the formation of our solar system.
Read more at Science Daily
"This is a game-changing breakthrough that brings us closer not only to treat blood disorders, but also deciphering the complex biology of stem-cell self-renewal machinery," said senior author Dr. Shahin Rafii, director of the Ansary Stem Cell Institute, chief of the Division of Regenerative Medicine and the Arthur B. Belfer Professor at Weill Cornell Medicine.
"This is exciting because it provides us with a path towards generating clinically useful quantities of normal stem cells for transplantation that may help us cure patients with genetic and acquired blood diseases," added co-senior author Dr. Joseph Scandura, an associate professor of medicine and scientific director of the Silver Myeloproliferative Neoplasms Center at Weill Cornell Medicine.
Hematopoietic stem cells (HSCs) are long-lasting cells that mature into all types of blood cells: white blood cells, red blood cells and platelets. Billions of circulating blood cells do not survive long in the body and must be continuously replenished. When this does not happen, severe blood diseases, such as anemia, bleeding or life-threatening infections, can occur. A special property of HSCs is that they can also "self-renew" to form more HSCs. This property allows just a few thousand HSCs to produce all of the blood cells a person has throughout one's life.
Researchers have long hoped to find a way to make the body produce healthy HSCs in order to cure these diseases. But this has never been accomplished, in part because scientists have been unable to engineer a nurturing environment within which stem cells can convert into new, long-lasting cells -- until now.
In a paper published May 17 in Nature, Dr. Rafii and his colleagues demonstrate a way to efficiently convert cells that line all blood vessels, called vascular endothelial cells, into abundant, fully functioning HSCs that can be transplanted to yield a lifetime supply of new, healthy blood cells. The research team also discovered that specialized types of endothelial cells serve as that nurturing environment, known as vascular niche cells, and they choreograph the new converted HSCs' self-renewal. This finding may solve one of the most longstanding questions in regenerative and reproductive medicine: How do stem cells constantly replenish their supply?
The research team showed in a 2014 Nature study that converting adult human vascular endothelial cells into hematopoietic cells was feasible. However, the team was unable to prove that they had generated true HSCs because human HSCs' function and regenerative potential can only be approximated by transplanting the cells into mice, which don't truly mimic human biology.
To address this issue, the team applied their conversion approach to mouse blood marrow transplant models that are endowed with normal immune function and where definitive evidence for HSC potential could rigorously tested. The researchers took vascular endothelial cells isolated from readily accessible adult mice organs and instructed them to overproduce certain proteins associated with blood stem-cell function. These reprogrammed cells were grown and multiplied in co-culture with the engineered vascular niche. The reprogrammed HSCs were then transplanted as single cells with their progenies into mice that had been irradiated to destroy all of their blood forming and immune systems, and then monitored to see whether or not they would self-renew and produce healthy blood cells.
Remarkably, the conversion procedure yielded a plethora of transplantable HSCs that regenerated the entire blood system in mice for the duration of their lifespans, a phenomenon known as engraftment. "We developed a fully-functioning and long-lasting blood system," said lead author Dr. Raphael Lis, an instructor in medicine and reproductive medicine at Weill Cornell Medicine. In addition, the HSC-engrafted mice developed all of the working components of the immune systems. "This is clinically important because the reprogrammed cells could be transplanted to allow patients to fight infections after marrow transplants," Dr. Lis said. The mice in the study went on to live normal-length lives and die natural deaths, with no sign of leukemia or any other blood disorders.
In collaboration with Dr. Olivier Elemento, associate director of the HRH Prince Alwaleed Bin Talal Bin Abdulaziz Al-Saud Institute for Computational Biomedicine, and Dr. Jenny Xiang, the director of Genomics Services, Dr. Rafii and his team also showed that the reprogrammed HSCs and their differentiated progenies -- including white and red bloods cells, as well as the immune cells -- were endowed with the same genetic attributes to that of normal adult stem cells. These findings suggest that the reprogramming process results in the generation of true HSCs that have genetic signature that are very similar to normal adult HSCs
The Weill Cornell Medicine team is the first to achieve cellular reprogramming to create engraftable and authentic HSCs, which have been considered the holy grail of stem cell research. "We think the difference is the vascular niche," said contributing author Dr. Jason Butler, an assistant professor of regenerative medicine at Weill Cornell Medicine. "Growing stem cells in the vascular niche puts them back into context, where they come from and multiply. We think this is why we were able to get stem cells capable of self-renewing."
If this method can be scaled up and applied to humans, it could have wide-ranging clinical implications. "It might allow us to provide healthy stem cells to patients who need bone marrow donors but have no genetic match," Dr. Scandura said. "It could lead to new ways to cure leukemia, and may help us correct genetic defects that cause blood diseases like sickle-cell anemia."
Read more at Science Daily
Average annual temperatures on the peninsula — the panhandle that points toward South America — have gone up nearly 3 degrees Celsius (5.4 degrees Fahrenheit) since the 1950s, when researchers started keeping detailed weather records. And the banks of moss that cover portions of the peninsula point to “a very widespread biological response” to climate change, said Matt Amesbury, a paleoclimatologist at Britain’s University of Exeter.
“Under future warming scenarios, there is likely to be a greening of the Antarctic Peninsula, both in terms of further increases in growth rates and also a likely expansion of the extent of these moss growths,” Amesbury said. As glaciers in the region continue to retreat, “It’s very likely in the future that we will see increased growth rates of the mosses, but also those mosses covering a wider area,” he said.
Amesbury is the lead author of the new study, published today in the scientific journal Current Biology. The peninsula’s moss banks grow in the summer and freeze in the winter — and core samples from those banks give scientists a window into how the plants behaved as temperatures rose.
The 150-year record the study collected from those cores reveals how much they grew in a particular year and how well the microbes living among them thrived.
“What we see is for about the first hundred years or so, all of these different proxies kind of tick along nicely at a very low level,” Amesbury said. “And then when we get to around the 1950s or 1980s … we see a dramatic increase in these different parameters across all of our sites and all of our methods.”
The findings are a follow-up to a 2013 study that examined core samples taken from a single point on the peninsula. This study included a total of five core samples taken from the previous location and three new sites on islands offshore; all cores showed signs of increased biological activity.
“The precise timing of these shifts varied, but the prevalent pattern of change indicates a widespread biological response to increasing temperature,” the study states.
Read more at Discovery News
May 17, 2017
|These are Ordovician-Silurian marine fossils from the museum of Tohoku University.|
There have been five mass extinctions since the divergent evolution of early animals 600 -450 million years ago. The cause of the third and fourth was volcanic activity, while an asteroid impact led to the fifth. But triggers of the first and second mass extinctions had, until now, been unknown.
The first mass extinction occurred at the end of the Ordovician. This age is between the divergence of the Ordovician and land invasion of vascular land plant and animals. Animals in the Ordovician-Silurian comprised marine animals like corals, trilobites, sea scorpion, orthoceras, brachiopods, graptolite, crinoid and jawless fish. Approximately 80% of species disappeared at the end of the Ordovician.
A team led by Dr. David S. Jones of Amherst College and Professor Kunio Kaiho of Tohoku University, looked into possible triggers of the first mass extinction. They took sedimentary rock samples from two places -- North America and southern China -- and analyzed the mercury (Hg) in them. They found Hg enrichments coinciding with the mass extinction in both areas.
This, they believe, is the product of large volcanic eruptions because Hg anomaly was also observed in other large igneous province volcanisms.
Huge volcanic eruptions can produce sulfate aerosols in the stratosphere. Sulfate aerosols are strong, light-reflecting aerosols, and cause global cooling. This rapid climate change is believed to be behind the loss of marine creatures.
Kaiho's team is now studying the second mass extinction in the hopes of further understanding the cause and processes behind it.
From Science Daily
|Researchers at UC Riverside are studying the world's oldest fossil animal, Dickinsonia, to learn more about the evolutionary history of animals.|
In their latest study, published today in the journal PLOS ONE, Scott Evans, a graduate student in the Department of Earth Sciences, and Mary Droser, a professor of paleontology, both in UCR's College of Natural and Agricultural Sciences, show that the Ediacaran-era fossil animal Dickinsonia developed in a complex, highly regulated way using a similar genetic toolkit to today's animals. The study helps place Dickinsonia in the early evolution of animal life, and showcases how the large, mobile sea creature grew and developed.
Dickinsonia was a flat, oval-shaped creature that ranged in size from less than an inch to several feet, and is characterized by a series of raised bands -- known as modules -- on its surface. These animals are of interest to paleontologists because they are the first to become large and complex, to move around, and form communities, yet little is known about them. For years, scientists have been debating the taxonomic status of Dickinsonia -- placing it with fungi, marine worms and jellyfish, to name a few. It is now generally accepted that Dickinsonia was an animal, now extinct.
"Part of this study was trying to put Dickinsonia in context in the development of early life. We wanted to know if these creatures were part of a group of animals that survived or a failed evolutionary experiment. This research adds to our knowledge about these animals and our understanding of life on Earth as an artifact of half a billion years of evolution," Droser said.
To study Dickinsonia, the researchers travelled to South Australia's desert outback, which was once underwater and is now home to an abundance of Ediacaran fossils.
They measured the size, shape and structure of almost 1,000 specimens of Dickinsonia costata, paying attention to the number and size of the modules. The work was done in collaboration with James Gehling of the South Australian Museum in Adelaide, Australia, who is a coauthor on the paper.
The study showed that Dickinsonia's development, and particularly that of the modules, was complex and systematic to maintain the oval shape of the animal. The accumulation of new modules, by a process called terminal addition, suggests that Dickinsonia developed in a related way to bilaterians, a complex group that display bilateral symmetry, including animals ranging from flies and worms to humans. However, the researchers do not believe Dickinsonia was ancestrally related to bilaterians, since it lacked other features that most bilaterians share, most notably a mouth, gut and anus.
Read more at Science Daily
Some 5,000 years on archaeologists believe the ruins could unlock the secrets of the Indus Valley people, who flourished around 3,000 BC in what is now India and Pakistan before mysteriously disappearing.
But they warn, if nothing is done to protect the ruins — already neglected and worn by time — it will fade to dust and obscurity, never taking its rightful place in history.
"Everybody knows Egypt, nobody knows Mohenjo Daro, this has to be changed," said Dr. Michael Jansen, a German researcher working at the sun-baked site on the banks of the Indus river in Pakistan's southern Sindh province.
Jansen is at the forefront of a new effort to promote the site internationally while finding ways to protect what is left.
In summer, temperatures can soar above 46 degrees Celsius (115 Fahrenheit). "There is enormous thermo-stress," said Jansen, adding that salt from the underground water table is also damaging the ruins.
But it's more than just the weather and time. Pakistan's bloody fight against militancy has also raised the specter of destruction by an Islamist group, much like Islamic State destroyed the ruins in Syria's Palmyra.
Most horrifying, however, is the wanton disregard for Mohenjo Daro — or "mound of the dead" — by ordinary citizens.
In 2014 police stood atop the main stupa as hundreds of people swarmed the site to, ironically, commemorate Pakistan's cultural heritage — complete with scaffolding, dancing, fireworks, heavy spotlights, and lasers.
Sardar Ali Shah, cultural minister in Sindh province, vowed never to let such a thing happen again.
"It's like you are jumping on the bed of a 5,000-year-old ailing patient," he told AFP.
Yet today curious visitors still roam the remains with impunity, many leaving rubbish in the once pristine-streets and wells.
“Foreigners are afraid”
Jansen and his Friends of Mohenjo Daro society aim to promote the site internationally, with plans to recruit Pakistanis around the world for conferences, seminars, and debates.
Dr. Kaleem Lashari, chief consultant to the Pakistani government over Mohenjo Daro, said they will also digitally archive the Indus script — which has never been deciphered — in hopes that making it accessible will increase the site's profile.
At the site itself, he said, technical reviews are being held to examine the water logging issue and other ways to shore up the ruins, while exploring new, modern technology that allows researchers to ascertain what lies beneath the surface in the portions of the city not yet excavated.
But, Lashari said, perhaps the biggest challenge remains Pakistan's international image, tarnished by extremism, corruption, poverty, and insecurity.
"Foreigners are afraid to visit Pakistan and the site because of the chronic issue of law and order," he warned.
All roads lead to equality?
The issues he cited underscore unsettling differences between modern day Pakistan and the civilization found among the ruins.
At their peak during the Bronze Age, the Indus Valley people are believed to have numbered up to five million, with Mohenjo Daro their largest and most advanced settlement.
Clay and metallic seals, coins, standardized weighing stones, gold and bronze ornaments, toys and whistles — the bric-a-brac of ancient lives have revealed volumes about thriving Indus trade and commerce.
The layout of the city itself suggests an egalitarian people more concerned with cleanliness than hierarchy, said Dr. Jonathan Mark Kenoyer of the University of Wisconsin.
"In Mesopotamia, the streets went from the city to the palace ... whereas in (Indus) cities all the streets were organized to allow access to the whole city," he said.
Read more at Discovery News
Warmer, drier conditions in much of the eastern United States has resulted in dozens of America’s most common tree species shifting their ranges over the last three decades, scientists report in a new study published in the journal Science Advances. Pines and other evergreens in the Southeast are growing farther north than they did in the years before 1980, while oaks, maples, and other Northeastern hardwoods are now growing more to the west of their traditional territories.
The geographic center of some species’ ranges has been moving more than a mile a year, said Songlin Fei, an ecologist at Purdue University who led the study. While previous studies have shown trees shifting northward and toward higher elevations in response to warming temperatures, Fei’s research suggests that the shift may have more to do with changes in rainfall.
“The Southeast has had a dramatic reduction in precipitation,” Fei said. “The western portion of the study area has more moisture available compared to the historical average.”
So while Florida still gets more rain than Indiana, new growth is moving rapidly toward the Midwest as a result of that change, with more drought-tolerant trees leading the way.
Of the 86 species included in the study, scientists saw westward shifts in 73 percent of them, while 62 percent shifted northward. The migration is far more rapid than has been seen in historical data: The center of some species’ ranges moved as much as 30 kilometers (19 miles) per decade.
Trees are always shifting in response to their environment. But the pace Fei and his colleagues clocked over the past 30 years is far more rapid than has been seen in historical records. It’s comparable to speeds estimated to have occurred as the glaciers retreated at the end of the last ice age, he said.
Climate change isn’t the only factor in that process – American woodlands are also under pressure from pests and development, Fei noted, and new plantings from conservation programs also affect their ranges. But climate change accounts for about 20 percent of the changes.
Fei and his colleagues compiled their results from reams of US Forest Service records — an annual count from more than 100,000 locations around the country.
“These are boots on the ground,” he said. “This is something I think is really unique about this study. This is empirical data — people on the ground, counting the trees, not modeling or estimating how many trees we have or how many we’ll have in the future.”
Read more at Discovery News
Tyrannomyrmex rex is a timid, finicky eater, new research finds. The ants can, however, turn to cannibalism in times of need.
Until now, these Asian ants were a complete mystery to science, despite being discovered more than 20 years ago. No one had ever collected more than a single specimen, and no one had ever observed a T. rex ant alive for an extended period of time. So when biologist Mark Wong stumbled across a colony of T. rex ants while conducting an ant diversity survey in Singapore, he knew he had something important.
He and his colleague Gordon Yong from the National University of Singapore carefully collected the colony, which consisted of 13 workers, as well as eggs, larvae and pupae (the liminal stage between larva and adulthood). They then observed the ants in an attempt to figure out what makes them tick. Because the study is the first of its kind, everything the researchers discovered is new, Wong told Live Science.
The T. rex ant was first discovered in Malaysia in 1994. It's part of the rare group of ants in the Tyrannomyrmex genus; there are only two other identified species. (T. dux from India and T. legatus from Sri Lanka.) The ants have pointed snouts, which may explain the T. rex namesake, Wong said.
In March 2016, Wong found the first known live colony of T. rex ants in a piece of rotting wood stuck in the ground in Singapore's Mandai area, just south of Malaysia and north of the Singapore Zoo. The ants were nesting in a second-growth forest that was once the home of 20th-century orchards and rubber plantations, Wong and Yong reported April 27 in the journal Asian Myrmecology.
In the field, it was apparent why the T. rex ant is so little-known. The colony was small, subterranean and unobtrusive. Ant collection methods rarely involve careful underground surveys, Wong said.
"Our finding of T. rex below the ground surface highlights the need for more focused exploration of the ant communities within this environment," he said.
Timid T. rex
In captivity, the colony further exhibited the retiring manner that has made these ants so elusive. They were more active at night than during the day, suggesting that they are probably nocturnal in the wild, Wong said. They are not aggressive. When exposed to a potential threat, like a millipede, the ants curled up and froze, likely hoping to be overlooked so they could run away when the immediate danger passed.
Despite offering the ants an absolute smorgasbord of food, Wong and Yong could not determine what the ant version of T. rex eats. They rejected termites, smaller ants, mites, millipedes and even honey, Wong said. When shown a drop of honey, they kept their distance, except for a tentative poke at the sticky substance with their antennae.
Read more at Discovery News
May 16, 2017
|Bioprosthetic ovary. By removing a female mouse’s ovary and replacing it with a bioprosthetic ovary, the mouse was able to not only ovulate but also give birth to healthy pups. The moms were even able to nurse their young.|
By removing a female mouse's ovary and replacing it with a bioprosthetic ovary, the mouse was able to not only ovulate but also give birth to healthy pups. The moms were even able to nurse their young.
The bioprosthetic ovaries are constructed of 3-D printed scaffolds that house immature eggs, and have been successful in boosting hormone production and restoring fertility in mice, which was the ultimate goal of the research.
"This research shows these bioprosthetic ovaries have long-term, durable function," said Teresa K. Woodruff, a reproductive scientist and director of the Women's Health Research Institute at Feinberg. "Using bioengineering, instead of transplanting from a cadaver, to create organ structures that function and restore the health of that tissue for that person, is the holy grail of bioengineering for regenerative medicine."
The paper will be published May 16 in Nature Communications.
How is this research different from other 3-D printed structures?
What sets this research apart from other labs is the architecture of the scaffold and the material, or "ink," the scientists are using, said Ramille Shah, assistant professor of materials science and engineering at McCormick and of surgery at Feinberg.
That material is gelatin, which is a biological hydrogel made from broken-down collagen that is safe to use in humans. The scientists knew that whatever scaffold they created needed to be made of organic materials that were rigid enough to be handled during surgery and porous enough to naturally interact with the mouse's body tissues.
"Most hydrogels are very weak, since they're made up of mostly water, and will often collapse on themselves," Shah said. "But we found a gelatin temperature that allows it to be self-supporting, not collapse, and lead to building multiple layers. No one else has been able to print gelatin with such well-defined and self-supported geometry."
That geometry directly links to whether or not the ovarian follicles, organized hormone-producing support cells surrounding an immature egg cell, will survive in the ovary, which was one of the bigger findings in the study.
"This is the first study that demonstrates that scaffold architecture makes a difference in follicle survival," Shah said. "We wouldn't be able to do that if we didn't use a 3-D printer platform."
How does this impact humans?
The scientists' sole objective for developing the bioprosthetic ovaries was to help restore fertility and hormone production in women who have undergone adult cancer treatments or those who survived childhood cancer and now have increased risks of infertility and hormone-based developmental issues.
"What happens with some of our cancer patients is that their ovaries don't function at a high enough level and they need to use hormone replacement therapies in order to trigger puberty," said Monica Laronda, co-lead author of this research and a former post-doctoral fellow in the Woodruff lab. "The purpose of this scaffold is to recapitulate how an ovary would function. We're thinking big picture, meaning every stage of the girl's life, so puberty through adulthood to a natural menopause."
Laronda is now an assistant professor at the Stanley Manne Children's Research Institute at the Ann & Robert H. Lurie Children's Hospital.
Additionally, the successful creation of 3-D printed implants to replace complex soft tissue could significantly impact future work in soft tissue regenerative medicine.
Technically, how does biological 3-D printing work?
3-D printing an ovary structure is similar to a child using Lincoln Logs, said Alexandra Rutz, co-lead author of the study and a former biomedical engineering graduate fellow in Shah's Tissue Engineering and Additive Manufacturing (TEAM) lab at the Simpson Querrey Institute. Children can lay the logs at right angles to form structures. Depending on the distance between the logs, the structure changes to build a window or a door, etc.
"3-D printing is done by depositing filaments," said Rutz, who is now a Whitaker International Postdoctoral Scholar at École Des Mines De Saint-Étienne in Gardanne, France. "You can control the distance between those filaments, as well as the advancing angle between layers, and that would give us different pore sizes and different pore geometries."
In Northwestern's lab, the researchers call these 3-D printed structures "scaffolds," and liken them to the scaffolding that temporarily surrounds a building while it undergoes repairs.
"Every organ has a skeleton," said Woodruff, who also is the Thomas J. Watkins Memorial Professor of Obstetrics and Gynecology and a member of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. "We learned what that ovary skeleton looked like and used it as model for the bioprosthetic ovary implant."
In a building, the scaffolding supports the materials needed to repair the building until it's eventually removed. What's left is a structure capable of holding itself up. Similarly, the 3-D printed "scaffold" or "skeleton" is implanted into a female and its pores can be used to optimize how follicles, or immature eggs, get wedged within the scaffold. The scaffold supports the survival of the mouse's immature egg cells and the cells that produce hormones to boost production. The open structure also allows room for the egg cells to mature and ovulate, as well as blood vessels to form within the implant enabling the hormones to circulate within the mouse bloodstream and trigger lactation after giving birth.
Read more at Science Daily
|Deforested land. Central American forests are giving way to pasture land for cattle ranches.|
The culprit? Cocaine.
The problem is not the cultivation of the coca plant -- which is processed into cocaine -- that is causing this "narco-deforestation." It results from people throughout the spectrum of the drug trade purchasing enormous amounts of land to launder their illegal profits, researchers say.
Results of the study, which was funded by the Open Society Foundations and supported by the National Socio-Environmental Synthesis Center, have just been published in the journal Environmental Research Letters.
"Starting in the early 2000s, the United States-led drug enforcement in the Caribbean and Mexico pushed drug traffickers into places that were harder to patrol, like the large, forested areas of central America," said David Wrathall, an Oregon State University geographer and co-author on the study. "A flood of illegal drug money entered these places and these drug traffickers needed a way that they could spend it.
"It turns out that one of the best ways to launder illegal drug money is to fence off huge parcels of forest, cut down the trees, and build yourself a cattle ranch. It is a major, unrecognized driver of tropical deforestation in Central America."
Using data from the Global Forest Change program estimating deforestation, the research team identified irregular or abnormal deforestation from 2001-2014 that did not fit previously identified spatial or temporal patterns caused by more typical forms of land settlement or frontier colonization. The team then estimated the degree to which narcotics trafficking contributes to forest loss, using a set of 15 metrics developed from the data to determine the rate, timing and extent of deforestation.
Strongly outlying or anomalous patches and deforestation rates were then compared to data from the Office of National Drug Control Policy -- considered the best source for estimating cocaine flow through the Central American corridor, Wrathall pointed out.
"The comparisons helped confirm relationships between deforestation and activities including cattle ranching, illegal logging, and land speculation, which traffickers use to launder drug trafficking profits in remote forest areas of Central America," Wrathall said.
They estimate that cocaine trafficking may account for up to 30 percent of the total forest loss in Honduras, Guatemala and Nicaragua over the past decade. A total of 30 to 60 percent of the forest losses occurred within nationally and internationally designated protected areas, threatening conservation efforts to maintain forest carbon sinks, ecological services, and rural and indigenous livelihoods.
"Imagine the cloud of carbon dioxide from all of that burning forest," Wrathall said. "The most explosive change in land use happened in areas where land ownership isn't clear -- in forested, remote areas of Honduras, Guatemala and Nicaragua, where the question of who owns the land is murky."
"In Panama, the financial system is built to launder cocaine money so they don't need to cut down trees to build ranches for money laundering. In Honduras, land is the bank."
Farming and cattle ranching aren't the only money laundering methods threatening tropical forests, the researchers say. Mining, tourism ventures and industrial agriculture are other ways drug money is funneled into legitimate businesses.
Wrathall said the impact affects both people and ecosystems.
"The indigenous people who have lived sustainably in these environments are being displaced as the stewards of the land," he said. "These are very important ecological areas with tremendous biodiversity that may be lost."
The authors says the solutions include de-escalating and demilitarizing the war on drugs; strengthening the position of indigenous peoples and traditional forest communities to be stewards of the remaining forest lands; and developing regional awareness of the issue.
"We are cruising through the last of our wild spaces in Central America," Wrathall said. "Obviously, ending the illegal drug trade would be the best solution, but that isn't going to happen. In fact, when drug enforcement efforts are successful, they often push the activity into remote areas that haven't had issues before, such as remote biodiversity hotspots."
Read more at Science Daily
|Blue marlin. Fishing typically removes the largest fish from the population.|
During the last two decades, there has been a lot of discussion on size-selective fishing causing genetic changes in exploited populations in contemporary timescales. Now, researchers have shown that fishing can cause expression changes in thousands of genes and that these changes can at least partly be associated with changes at DNA level.
"Removing the largest individuals from the experimentally exploited populations induced differences in the expression of more than 4,000 genes after five generations of size-selective harvesting," says postdoctoral researcher Silva Uusi-Heikkilä from the University of Turku.
The harvesting experiment was done in collaboration between the University of Turku and the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin. For five generations, experimental zebrafish populations were harvested by using two harvesting strategies: removing the largest individuals and removing individuals randomly with respect to body size. After harvesting, the populations were allowed to recover for six generations.
"Changes in gene expression help fish to adapt to different selective pressure," Uusi-Heikkilä says. "It's noteworthy, however, that the differences in expression pattern between the harvest treatments remained after the recovery."
In addition to the changes in gene expression, the expression variance was also affected by fishing: fishing decreased the variance. Gene expression variation can be important because it may help fish to adapt to changes in the environment and the climate.
"After the recovery period, the gene expression variance increased but only in randomly harvested fish. The variance continued to decrease among fish where the largest individuals had been removed," Uusi-Heikkilä says.
Reduced variation caused by size-selective harvesting in exploited populations can slow down the recovery. "Moderate fishing pressure combined with protection of large individuals may advance the recovery of fish populations."
From Science Daily
|Domesticated crops have been transformed almost beyond recognition in comparison with their wild relatives - a change that happened during the early stages of farming in the Stone Age.|
Researchers from the Grantham Centre for Sustainable Futures at the University of Sheffield have shed light on how hunter-gatherers first began farming and how crops were domesticated to depend on humans.
Domesticated crops have been transformed almost beyond recognition in comparison with their wild relatives -- a change that happened during the early stages of farming in the Stone Age.
For grain crops like cereals, the hallmark of domestication is the loss of natural seed dispersal -- seeds no longer fall off plants but have become dependent on humans or machines to spread them.
Professor Colin Osborne, from the Grantham Centre for Sustainable Futures at the University of Sheffield, said: "We know very little about how agriculture began, because it happened 10,000 years ago -- that's why a number of mysteries are unresolved. For example why hunter-gatherers first began farming, and how were crops domesticated to depend on people.
"One controversy in this area is about the extent to which ancient peoples knew they were domesticating crops. Did they know they were breeding domestication characteristics into crops, or did these characteristics just evolve as the first farmers sowed wild plants into cultivated soil, and tended and harvested them?"
The new research, published in the journal Evolution Letters, shows the impact of domestication on vegetable seed size.
Any selective breeding of vegetables by early farmers would have acted on the leaves, stems or roots that were eaten as food, but should not have directly affected seed size.
Instead, any changes in vegetable seed size must have arisen from natural selection acting on these crops in cultivated fields, or from genetic links to changes in another characteristic like plant or organ size. In the last instance, people might have bred crops to become bigger, and larger seeds would have come along unintentionally.
The University of Sheffield researchers gathered seed size data from a range of crops and found strong evidence for a general enlargement of seeds due to domestication.
They discovered domesticated maize seeds are 15 times bigger than the wild form, soybean seeds are seven times bigger. Wheat, barley and other grain crops had more modest increases in size (60 per cent for barley and 15 per cent for emmer wheat) but these changes are important if they translate into yield.
"We found strong evidence for a general enlargement of seeds due to domestication across seven vegetable species," said Professor Osborne.
"This is especially stunning in a crop like a sweet potato, where people don't even plant seeds, let alone harvest them. The size of this domestication effect falls completely within the range seen in cereals and pulse grains like lentils and beans, raising the possibility that at least part of the seed enlargement in these crops also evolved during domestication without deliberate foresight from early farmers."
Professor Osborne added: "Our findings have important implications for understanding how crops evolved, because they mean that major changes in our staple crops could have arisen without deliberate foresight by early farmers.
Read more at Science Daily
According to researchers at Lehigh University, KELT-11b has by far the largest atmospheric scale height of any ever studied, including our own solar system. Scale height describes the height at which an atmosphere “hugs” a planet, and while the scale height of Saturn’s atmosphere is about 60 km (37 miles) and Earth’s is about 8 km (5 miles), KELT-11b’s is a whopping 2,763 km (1,716 miles).
And the oddities of KELT-11b don’t stop there. The planet itself is one of the most puffy and inflated planets in the known universe, with the density of a Styrofoam ball — the kind that students use to simulate planetary bodies in classroom presentations.
“It is highly inflated, so that while it's only a fifth as massive as Jupiter, it is nearly 40 percent larger, making it about as dense as Styrofoam, with an extraordinarily large atmosphere,” said Joshua Pepper, astronomer and assistant professor of physics at Lehigh University, who led the study.
Pepper called KELT-11b an “extreme” version of a gas planet. It is orbiting very close to its host star, circling it in less than five days. The star, KELT-11, has started using up its nuclear fuel and is evolving into a red giant, so the planet will eventually be engulfed by its star and not survive the next hundred million years.
But this star is extremely bright — the brightest known transiting exoplanet host that can be seen from the southern hemisphere — and is the sixth brightest transit host to date. Such a bright star allows for precise measurements of the planet's atmosphere.
The team wrote in their paper that all “these attributes make the KELT-11 system a valuable target for follow-up and atmospheric characterization and it promises to become one of the benchmark systems for the study of inflated exoplanets.”
Pepper also said that KELT-11b is “an excellent testbed for measuring the atmospheres of other planets,” and that it will help astronomers develop the best tools to see the types of gases in atmospheres, specifically for assessing habitability or possible life on distant exoplanets.
“We don't know of any real Earth-like planets or stars for which we can measure their atmospheres, though we expect to discover more in future years,” Pepper said. “These [giant gas] planets are the gold standards or testbeds for learning how to measure the atmospheres of planets.”
Another unique aspect of this exoplanet is that it was found with the help of citizen scientists. In fact, 40 amateur scientists from 10 countries contributed directly to the discovery of KELT-11b and are listed as co-authors on the paper.
The KELT (Kilodegree Extremely Little Telescope) survey uses two small robotic telescopes in Arizona and in South Africa. The telescopes scan the sky every night, measuring the brightness of about five million stars. Like the exoplanet-finding “champion,” the Kepler space telescope, KELT looks for stars that seem to dim slightly at regular intervals, which can indicate a planet is orbiting that star and eclipsing it, called a transit.
But most of the planets found by Kepler orbit faint stars, making it difficult to measure the planets' properties precisely.
“The KELT project is specifically designed to discover a few scientifically valuable planets orbiting very bright stars, and KELT-11b is a prime example of that,” Pepper said.
KELT specifically looks for gas giant planets orbiting bright stars, but the team didn’t expect to find planets with such low mass and large sizes.
”We were very surprised by the amazingly low density of this planet,” Pepper said. “It's extremely big for its mass. It's got a fifth of the mass of Jupiter but is puffed up into this really underdense planet.”
They hope that further study of this world by the Hubble and Spitzer space telescopes will provide additional information about the mechanism that causes inflated planets.
Read more at Discovery News
May 15, 2017
|This wildebeest fossil skull was excavated at the Ledi-Geraru research site, Ethiopia.|
But how do you re-create specific environments from millions of years ago to understand where our ancient ancestors lived?
Paleoanthropologists use animal fossils like proxy time machines to re-create what past environments were like. If animal fossils indicate browsing on tree leaves, like giraffes and monkeys do, then they know that the environment was characterized by woody trees and significant rainfall. If the fossils suggest grazing on grass, as many antelopes do, then the environments would have been open and arid with grassy plains.
Scientists have long suggested that global cooling and the spread of grassy environments set the stage for the beginnings of Homo.
"A growing body of evidence has hinted at this connection," said Joshua Robinson, postdoctoral researcher with the Institute of Human Origins, "but, until now, we had no direct environmental data for the origins of Homo now that its been pushed back in time."
Following the discovery of the Ledi-Geraru jaw, an intensive environmental study of the eastern African Plio-Pleistocene -- from around 3.5 million years ago to 1.0 million years ago -- was conducted in order to investigate these long-standing hypotheses.
The study, coauthored by ASU researchers Joshua Robinson, John Rowan, Christopher Campisano and Kaye Reed with University of South Florida researcher Jonathan Wynn, in the journal Nature Ecology and Evolution, offers the first comprehensive assessment of the ecological contexts of the transition from Australopithecus to Homo.
The time period around 2.8 million years ago is particularly important for the human fossil record of eastern Africa. Thirty kilometers to the west of Ledi-Geraru is Hadar, where the famous "Lucy" fossil of Australopithecus afarensis was found in 1974 by ASU professor Donald Johanson and dated to 3.2 million years ago. The geological sequence at Hadar, however, ends around 2.95 million years ago and is thus missing the important transitional period between the end of Australopithecus and earliest Homo.
Using stable isotopes of fossil teeth, the researchers found that early Homo at Ledi-Geraru was indeed associated with open and arid grassy environments. Results show that almost all animals found with early Homo at Ledi-Geraru fed on grass, including some that consumed substantial amounts of tree leaves prior to 2.8 million years ago. The diet of early Homo at Ledi-Geraru, however, appears to be indistinguishable from that of the earlier Australopithecus, implying that a change in diet is not a characteristic of the origins of Homo.
"We weren't necessarily surprised that the diet of early Homo was similar to Australopithecus," said Chris Campisano, research associate with the Institute of Human Origins and associate professor in the School of Human Evolution and Social Change. "But we were surprised that its diet didn't change when those of all the other animals on the landscape did."
Placing Ledi-Geraru in a regional context indicates that eastern Africa environments at this time were not homogeneous. The ecology of the lower Awash Valley shifted from a wet and wooded environment at the time of the disappearance of Australopithecus around three million years ago to a dry and open landscape at the time of early Homo 2.8 million years ago.
"Although Lucy's species persisted through many environmental changes in the Hadar sequence," School of Human Evolution and Social Change graduate student John Rowan said, "it seems the species was unable to persist as really open environments spread in the Afar during the late Pliocene."
Furthermore, these results indicate that the spread of grassy environments at Ledi-Geraru occurred earlier than in the Turkana Basin of Kenya and Ethiopia, which continued to have wooded regions that supported browsers and other mammals that fed on both trees and grasses.
Read more at Science Daily
|If space and time are fluctuating, why can’t we feel it?|
PhD student Qingdi Wang has tackled this question in a new study that tries to resolve a major incompatibility issue between two of the most successful theories that explain how our universe works: quantum mechanics and Einstein's theory of general relativity.
The study suggests that if we zoomed in-way in-on the universe, we would realize it's made up of constantly fluctuating space and time.
"Space-time is not as static as it appears, it's constantly moving," said Wang.
"This is a new idea in a field where there hasn't been a lot of new ideas that try to address this issue," said Bill Unruh, a physics and astronomy professor who supervised Wang's work.
In 1998, astronomers found that our universe is expanding at an ever-increasing rate, implying that space is not empty and is instead filled with dark energy that pushes matter away.
The most natural candidate for dark energy is vacuum energy. When physicists apply the theory of quantum mechanics to vacuum energy, it predicts that there would be an incredibly large density of vacuum energy, far more than the total energy of all the particles in the universe. If this is true, Einstein's theory of general relativity suggests that the energy would have a strong gravitational effect and most physicists think this would cause the universe to explode.
Fortunately, this doesn't happen and the universe expands very slowly. But it is a problem that must be resolved for fundamental physics to progress.
Unlike other scientists who have tried to modify the theories of quantum mechanics or general relativity to resolve the issue, Wang and his colleagues Unruh and Zhen Zhu, also a UBC PhD student, suggest a different approach. They take the large density of vacuum energy predicted by quantum mechanics seriously and find that there is important information about vacuum energy that was missing in previous calculations.
Their calculations provide a completely different physical picture of the universe. In this new picture, the space we live in is fluctuating wildly. At each point, it oscillates between expansion and contraction. As it swings back and forth, the two almost cancel each other but a very small net effect drives the universe to expand slowly at an accelerating rate.
Read more at Science Daily
How long? Like millions of years.
Once oxygen disappears in the seas — a state known as anoxia — changes in the atmosphere will eventually trigger forest fires that will spark a chain of events leading to oxygen returning after millenniums, according a study in the journal Nature Communications authored by researchers at the University of Exeter in Britain.
“It’s going to take a long, long time for the Earth’s system to rebalance,” said study co-author Sarah Baker, a Ph.D candidate in geography at Exeter. “It’s not a flip of the switch thing. It’s not going to take a day a week or a few years.”
Scientists have determined that oceanic oxygen levels are decreasing, killing fish and other life in the Gulf of Mexico, the Baltic Sea, and elsewhere. Agricultural runoff that feeds algae that becomes food for oxygen-sucking bacteria when it decomposes and warmer temperatures that make it harder for water to chemically absorb oxygen from the atmosphere are prime causes of the drop-off.
Making a connection between volcanic eruptions 183 million years ago that emitted massive quantities of carbon into the air — causing deadly drops in oxygen levels in the ocean and massive marine extinctions — Baker and her colleagues studied layers of fossilized charcoal in Wales and Portugal from the same period to see how the land might have reacted.
Their findings depict mechanisms that take place on a geological time scale.
The researchers surmised that carbon spikes in the water after a so-called “anoxic event” like a catastrophic volcanic eruption would cause oxygen levels in the ocean to collapse, spurring the growth of marine plants. More plants would then theoretically produce more oxygen that would eventually make it into the atmosphere.
Confirming their thesis, the fossil record showed an uptick in wildfires around 1 million years after the volcano eruptions. More oxygen in the air correlates to fires, said Baker.
Taking their theorizing a step further, they inferred that more wildfires would have cleared the land of vegetation that helps erode rocks that naturally provide marine nutrients like phosphorus — an ingredient in dish detergents and fertilizers that causes aquatic algae blooms today. The lack of those nutrients would then depress plant populations in the water, robbing fish and other creatures of food. Fewer organisms breathing oxygen would result in oxygen levels rising in the water.
Around 800,000 years later, the heightened wildfire activity ebbed, the researchers found, suggesting the oxygen-carbon balance on the planet had returned to balance.
Baker admitted that the fossil record was just one piece of an enormous puzzle. But the fossils confirmed 14-year-old research that reached similar conclusions using mathematical models, she said.
Pennsylvania State University Geoscientist Katherine Freeman had questions about the findings. It’s not clear what kind of vegetation was burning during the periods that Baker and her fellow researchers had studied. Certain plants could have produced more charcoal during normal wildfire seasons.
Read more at Discovery News
“When we first saw them, we knew they were unusual, but the feeling wasn’t so much, ‘Eureka!’ as it was, ‘What the heck is this?’” said Moscato, who is the programming coordinator at the Center for Science Teaching and Learning at East Tennessee State University. “Before we could be sure this was something new, we had to look at just about every similar species of snake we could think of, alive or extinct.”
The extensive investigation determined that the bones belonged to a new five-million-year-old fossil species, which the researchers named Zilantophis schuberti, or “Schubert’s Winged Serpent.” Their work was published in the Journal of Herpetology.
“Schubert” honors Blaine Schubert, the executive director of East Tennessee State’s Don Sundquist Center of Excellence in Paleontology. He was the adviser of both Jasinski and Moscato when they were students there.
The snake, which when alive measured about 12 to 16 inches long, did not have actual wings and therefore could not fly, yet it was a compact powerhouse. The researchers believe that the winged projections were likely attachment sites for back muscles.
The unusual features did not last long, however, in evolutionary time.
“Those wing-like projections are probably something that evolved uniquely in Zilantophis and disappeared with it when it went extinct,” Moscato explained.
The new fossil species is thought to be most closely related to rat snakes and kingsnakes, both of which are relatively common in North America today. Schubert’s Winged Serpent had a unique life in and around the sinkhole, though. It lived in leaf litter on land close to the water that once filled the prehistoric depression.
The researchers suspect that the snake nabbed tiny fish in the water as well as insects, worms, and small amphibians. All were once plentiful at the location, named the Gray Fossil Site.
It has always been a snake-eat-snake world, so larger snakes could have preyed upon Schubert’s Winged Serpent, as well as birds of prey, large toads, and small mammals that were living at the time in what is now eastern Tennessee.
“Zilantophis would have had to make sure to stay out from under the feet of barrel-chested hornless rhinos, saber-toothed cats, shovel-tusked elephants, and the most abundant large animal at the site: tapirs,” Moscato said. “The site’s most famous animal, the red panda (Pristinailurus bristoli), was larger and more omnivorous than the modern-day version. It might even have made a grab for Zilantophis if given the chance!”
For millions of years, well into the Dinosaur Age, North America was once home to many ancient species of boas. After non-avian dinosaurs went extinct around 65 million years ago, boas were still going strong. That all began to change starting about 30 million years ago, when a gradual shift in the climate led to the replacement of many forests with grasslands.
“In North America, this shift gradually edged out the ‘old guard’ of boas, but was favorable for the kinds of snakes we have today,” Moscato said, noting that most of today’s snakes belong to the family Colubridae. Two-thirds of all known living snakes are colubrids, which are typically smaller than boas.
Read more at Discovery News
May 14, 2017
|Picture of a lung organoid.|
A paper detailing the discovery was published in the April 24 online issue of Nature Cell Biology.
Organoids are 3-D structures containing multiple cell types that look and function like a full-sized organ. By reproducing an organ in a dish, researchers hope to develop better models of human diseases, and find new ways of testing drugs and regenerating damaged tissue.
"Researchers have taken up the challenge of creating organoids to help us understand and treat a variety of diseases," said Hans-Willem Snoeck, PhD, professor of medicine (in Microbiology & Immunology) at CUMC and lead investigator of the study. "But we have been tested by our limited ability to create organoids that can replicate key features of human disease."
The lung organoids created in Dr. Snoeck's lab are the first to include branching airway and alveolar structures, similar to human lungs.
To demonstrate their functionality, the researchers showed that the organoids reacted in much the same way as a real lung does when infected with respiratory syncytial virus (RSV). Additional experiments revealed that the organoids also responded as a human lung would when carrying a gene mutation linked to pulmonary fibrosis.
RSV is a major cause of lower respiratory tract infection in infants and has no vaccine or effective antiviral therapy. Idiopathic pulmonary fibrosis, a condition that causes scarring in the lungs, causes 30,000 to 40,000 deaths in the U.S. each year. A lung transplant is the only cure for this condition.
"Organoids, created with human pluripotent or genome-edited embryonic stem cells, may be the best, and perhaps only, way to gain insight into the pathogenesis of these diseases," Dr. Snoeck says.
From Science Daily
|This graphic reflects three scales: the macroscopic snowflake (blue lines), the molecular structure (red tube model), and the electron scattering diffraction (density plot).|
Now, research led by a Tufts University chemist has answered Kepler's questions by shedding new light on this process by combining an electron backscatter with a large single crystal ice model. In a study published in the Proceedings of the National Academy of Sciences, scientists discovered that an ice crystal's flat sides are formed by a hexagon that is larger and consists of a central water molecule surrounded by six others in the same layer.
Mary Jane Shultz, Ph.D., a chemistry professor in the School of Arts and Sciences at Tufts University and first author of the study, said the chair-form hexagon has three molecules in one layer and three more slightly lower in what is called a bilayer structure. The six flat sides of a snowflake grow from a hexagon formed within one layer. This larger hexagon is rotated 30 degrees relative to the chair-form hexagon.
"Snowflakes grow from water vapor. Faces that release the most heat (per unit area) vaporize," said Shultz. "The face with the least heat release is the hexagonal face; next is the flat face of the larger hexagon. The flat side of the chair-form hexagon releases the most heat per area, which vaporizes itself. Thus, the snowflake hexagonal prism has flat sides that correspond to the larger hexagon."
The study findings debunk previous assumptions that snowflakes grow from the flat sides of the chair-form hexagon, Shultz said.
To determine how the formation occurs, researchers built a model that balances the heat released when molecules are incorporated in the solid lattice against probability of successful attachment. Combining macroscopic and molecular-level techniques allowed the team to investigate the same surface at different scales.
The macroscopic probe has been used for decades to investigate ice. This technique produces the beautiful visual images of the macroscopic hexagonal shape. The molecular-level probe is more recent. While an X-ray is commonly used to show the molecular-level, Shultz and her team opted to use the electron backscatter diffraction technique, which produces orientation density plots that are more illustrative and visually compelling.
"Careful sample orientation tracking enabled us to link the two images to produce the connection," she said.
The research confirmed that snowflake points align with the crystallographic a axes shown as hot spots in the electron backscatter data. The significance is that the flat side of a snowflake consists of a bilayer structure. The basal face is a chair-form hexagon; the up-down alteration forms a bilayer. The flat side is a boat-form hexagon consisting of pairs of water molecules bridging pairs in the lower half of the bilayer. Flexibility and mobility of a pair is expected to result in unique reactivity of this face, including potentially catalyzing conversion of gases like CO2 and nitrogen oxides in the atmosphere. Shultz said the team is now investigating this reactivity.
From Science Daily