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Model can predict tariff impact ahead of time

Fri, 2019-04-19 13:51

New research explores the complexity of tariffs as a trade tool in a global economy.

A global trade war initially launched with Trump Administration tariffs on Chinese steel in 2018 indeed boosted domestic steel production. But as analysts learned how higher costs would affect downstream manufacturers—and later affect demand for domestic steel—stock prices for US steelmakers tumbled by almost 50 percent year-over-year.

Researchers cited that anecdote—among many others—in their new work. Their paper also establishes a supply chain model to explain those effects and proposed that, in some cases, the effects were foreseeable when accounting for strategic, multi-party interactions and competition.

“The logic that levying tariffs will help protect and strengthen the corresponding domestic industries is not that straightforward in today’s global economy,” write Lingxiu Dong and Panos Kouvelis in their paper, which was accepted for publication in the journal Manufacturing & Service Operations Management.

When policymakers employ a tariff—a tax on imported or exported goods—as a tool to protect a domestic industry from foreign manufacturing, they may assume the industry operates in a vacuum. The effect of imposing a tariff on, say, soybean exports, however, has ripple effects throughout the supply chain for both soybean farmers and their suppliers as well as for the downstream consumers of soybeans, says Kouvelis, professor of operations and manufacturing management at Washington University in St. Louis.

Following the ripples

In retaliation for earlier US tariffs, the Chinese government imposed a 25 percent tariff on 106 US goods—including soybeans—in April 2018. Chinese buyers of US soybeans, which pork producers often use as feed, have started finding suppliers in Brazil and Argentina, avoiding higher prices.

Thus, the Chinese market begins to dry up for US soybean farmers, possibly forever. Agribusiness firms in South America are expanding aggressively in the region to capture the Chinese market opportunity.

“Suddenly, they realize there’s another sourcing opportunity, and they seize the opportunity,” says Kouvelis.

“Tariffs have short-term benefits and long-term implications that are frequently quite unpleasant. In the long term, firms adjust to the new realities.”

Kouvelis and Dong, professor of operations & manufacturing management, began working on their paper about 10 months after the Trump Administration levied the first tariffs on steel and aluminum imports from all nations, including China, in March 2018.

“It’s a very timely topic,” Kouvelis says. “What we thought as we started reading the stories was that the impact is not that obvious.” Under the theory, tariffs would protect US manufacturers from cut-rate imports of foreign-made steel and aluminum. In theory, US firms could expand, hire and supply more US consumers of steel and aluminum. But that’s not how it works in reality.

“Trade policies such as tariffs have significant implications not only for the industries the policies were intended to protect, but also for the complex supply chain that they are a part of,” Dong says. “The net effect of those reactions on the industry and the supply chain is hard to predict.”

The researchers did not conclude that tariffs were a poor instrument for executing trade policy. Rather, policymakers must be aware of the likely effects if they use tariffs. For example, tariffs may indeed restrict trade with a region of a globe—but that doesn’t mean all the companies within that region will be US firms.

“Companies go where they see the opportunities and the growth,” Kouvelis says. “We are moving towards regional supply chains, and in many cases that might be a desirable supply chain outcome. Shorter and market-focused chains are often argued as agile and lean. But tariffs might not have been the best way to end up there, and they may have caused competitive headaches for some of the US companies.”

Predicting the impact

In their research, the pair developed a number of mathematical models accounting for different variables in the supply chain. They examined where the supplier of raw materials is located relative to the manufacturers of finished goods, for example. Or whether the suppliers or manufacturers have multiple production plants in international locations or localized facilities.

Other variables include the costs of shipping goods or finished products and the ability (or inability) of a company to pivot to new suppliers or production facilities as costs rise.

Throughout their paper, the two researchers share anecdotes about how the tariffs have affected companies and industries. Motorcycle maker Harley-Davidson, for example, experienced higher production costs in the United States, thanks to steel and aluminum tariffs and an increase of $2,200 per bike from shipment costs resulting from European retaliatory tariffs. The company ended up shifting some of its production to Europe to better deal with such cost increases.

The model Kouvelis and Dong created would predict what is actually happening: US carmakers are shifting production to China, especially so for the lower-end car models—employing more Chinese workers and fewer US workers.

Meanwhile, the researchers captured the complexity of the auto industry, where US-made cars may be using Chinese components that US tariffs potentially affect, while Chinese tariffs also affect the final products the US exports to China.

The model Kouvelis and Dong created would predict what is actually happening: US carmakers are shifting production to China, especially so for the lower-end car models—employing more Chinese workers and fewer US workers. US production facilities will be further de-labored through flexible automation.

“We can tell you in stories after the fact some of the impact, but we need a model that predicts the direction of change and explains the stories,” Kouvelis says.

“What are the factors you have to think about so you can predict the move before it happens—rather than being a Monday morning quarterback?”

Source: Washington University in St. Louis

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Logging hit ‘fast forward’ on an entire river’s erosion

Fri, 2019-04-19 09:37

The effects of logging show that human activity can significantly erode bedrock, causing geology to fast forward, according to new research.

Geologic time is supposed to be slow, and the most solid object should be bedrock. But the new study, which focuses on a picturesque river in central Washington state called the Teanaway River, upends both concepts.

“In the last century, we have more river incision in this area than expected. Something caused these rivers to start eroding a lot more,” says lead author Sarah Schanz, a postdoctoral researcher at Indiana University.

“We know the Teanaway River has eroded into bedrock before, naturally—it has some terraces that are 1,800 years old. But this current cycle is anthropogenic, or human-driven.”

Exposed bedrock in the Teanaway River forms flutes and grooves—depressions where gravel gets trapped in a pothole and erodes it further. The oblong depressions are popular summer bathing spots. (Credit: Sarah Schanz/Indiana U.)

The research shows that practices related to logging caused bedrock incision of up to 2 meters (6 feet) along the riverbed. As much as a half of what had been a floodplain transformed into a new terrace abutting the river.

“This is the first time that we’ve been able to pinpoint erosion into bedrock due to human action,” Schanz says. “Most rivers are eroding at about a tenth of a millimeter per year. This is about 100 times that amount.”

The discovery means this beautiful riverbank resulted from human action, not natural forces. It could change how geologists think about landscapes in other parts of the world, such as Taiwan, with its long history of intense human activity.

Workers decking logs on the bank of the Teanaway River in 1920. (Credit: Frederick Krueger Photographs 207/Central Washington University Archives)

The study began 20 years ago when coauthor Brian Collins, a senior lecturer in river geology at the University of Washington, was curious about why there was so much exposed bedrock in the Teanaway.

Collins also noticed unusual river terraces, the stepped structures along the river bank resulting from cycles of the river flooding and then running more quickly, cutting a new channel deeper into the sediment. He led a 2016 study that calculated short-term changes in the Teanaway’s western fork and suggested logging may have caused the river to cut a new channel.

This site in a community forest offered good access for regular visits by the research team and undergraduate assistants to all three forks. By combining newspaper records, material from the University of Washington’s Libraries Special Collections, Central Washington University, and the local Kittitas County historical society, the researchers pieced together and confirmed the full history.

Before logging roads existed, companies built temporary “splash dams” high up on the slope with all the logs and then broke up the dam with tools or explosives. Released water helped send logs shooting down to the mills.

“It was such an event that schools closed, and newspaper records show it really well,” Schanz says. “People who are still alive today, some of their earliest memories are of going to see it.”

Key to the process is that loggers would clear away debris to give the logs a clear shot down the river. This removed barriers that held back sediment and cleared out much of the gravel from the riverbed. Such events, the authors believe, caused the erosion to change dramatically.

Field assistant Alex Pacubas stands next to one of the fluted bedrock channels of the West Fork Teanaway River in summer 2015. In the background, you can see a slab of bedrock that eroded off the channel in the foreground. (Credit: Sarah Schanz/Indiana U.)

“If you have too much sediment, you’re basically protecting the river from erosion. But if you have not enough sediment, as that sediment is moving along, it starts to hit the bedrock and erode it,” Schanz says.

David Montgomery, a professor of earth and space sciences, and the other two coauthors used many techniques to analyze the four youngest terraces on the river’s edge, including LIDAR maps, carbon dating of rocks, and computer models. In 1999, the team even hammered nails into the bedrock and measured the erosion rates directly.

David Montgomery and doctoral student Vivian Leung study the bank of the Teanaway River where the team hammered a nail into the bedrock in 1999 to measure the erosion rate directly. (Credit: Brian Collins/U. Washington)

Many rivers, including the Teanaway, have individual features that show evidence of human impact on areas of bedrock. But this is the first time an entire river basin is found to have been transformed by human activity.

“This is a direct topographic signature of the Anthropocene, the ‘age of humans’ that we now live in,” Montgomery says. “The finding that terrace surfaces in the Teanaway are recently-abandoned floodplains suggests that similar landforms around the world may also reflect the influence of human activity.”

The team recently published an overview paper looking at where river terraces have formed worldwide over the past 4,000 years. The authors showed that in many cases, river terrace formation coincided with deforestation.

“It’s sort of a hand-wavey linkage at this point, but I think this could be prevalent worldwide,” says Schanz. “It’s just not a signal that we’ve known to look for before.”

Schanz also plans to explore what the finding means for how river canyons form through natural processes.

“I think the human part is really interesting, but what has broader implications, for me, is the proof that if you change how sediment moves through a river, you can change erosion rates,” Schanz says.

The study appears in the Proceedings of the National Academy of Sciences. The National Science Foundation funded the research.

Source: University of Washington

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Find greater success by embracing ‘soft’ deadlines

Fri, 2019-04-19 09:29

New research on project management finds that embracing uncertainty around deadlines can lead to greater success.

The work offers a way to peek under the hood of deadlines, map out their uncertainty, and fold it into a project management system.

“Our society tends to think of deadlines as less flexible than other aspects of a project, but in reality, that’s often not the case…”

“Our society tends to think of deadlines as less flexible than other aspects of a project, but in reality, that’s often not the case,” says Tom Logan, a doctoral student in industrial and operations engineering at the University of Michigan. “When we recognize that, it enables us to do some really novel things.”

Success rate

Logan worked on the project with Robert Bordley, professor of practice and program director in Integrative Systems + Design at the University of Michigan College of Engineering.

In a series of experiments testing the team’s technique, it improved the success rate of projects by up to 40 percent. That improved success rate can manifest itself in a variety of ways, including more timely completion, projects that better fit the original requirements, and improved profitability.

“A deadline is just another stakeholder requirement and we all know that stakeholder requirements hold a certain amount of uncertainty,” Bordley says. “We can’t eliminate that uncertainty, but we can often quantify it. And I’ve found that the value of doing that is very big.”

The solution, which appears in the European Journal of Operational Research, is to work with stakeholders to understand the uncertainty and work it into the project as an active, manageable variable.

How to work with stakeholders

The hard part comes first—managers should ask for more than just the optimistic and pessimistic completion dates that are part of Project Evaluation and Review Technique, the statistical tool that underpins modern project management. This requires an honest sit-down with stakeholders and some digging to learn the reasoning behind those dates.

“Stakeholders are always dealing with a complex set of uncertainties, but they are rarely shared with project managers. The goal is to bring the two worlds closer together and incorporate the knowledge that’s uncovered into the management process,” Bordley says.

“I like to ask stakeholders to think of a situation that would cause a deadline to get pushed forward by a month, for example. Tell me about that situation, estimate how likely it is to happen. Focus on the extremes. That way, you end up with optimistic and pessimistic deadlines that are more than just numbers.”

Find your bull’s-eye

With optimistic and pessimistic deadlines in hand, the next step is to indicate the uncertainty of the deadline within the project management system.

To do this, Bordley says, add an additional, virtual activity to a project. The activity begins on the optimistic completion date and ends on the pessimistic completion date, creating a virtual bull’s-eye for on-time completion. As long as the project finishes between the optimistic and pessimistic dates, it’s considered on time. The more uncertainty in the deadline, the larger the bull’s-eye.

The manager can then make decisions based on the uncertainty of the deadline. A less certain deadline means a larger target and more flexibility to focus resources on other project requirements that are more certain.

The virtual activity can also be adjusted as the project progresses—shrinking as the deadline firms up or growing as uncertainty mounts. Either way, it gives the manager a running forecast of deadline uncertainty and the ability to plan accordingly.

“This technique can save a manager from spending a lot of time and resources on a deadline that might not matter much in the end,” Bordley says. “If it’s soft, the manager can quickly see that it’s soft and focus resources on other requirements that are less likely to change.”

To test the effectiveness of the modification, the team built a computer model that cycled through 1,000 simulated projects. First, they applied a traditional PERT project management model that ignores deadline uncertainty, then they applied their modified model that recognizes deadline uncertainty and adjusts resources as needed.

Bordley and Logan devised the strategy along with Jeffrey Keisler, a professor at the University of Massachusetts-Boston.

Source: University of Michigan

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Self-driving cars could make for more pollution

Fri, 2019-04-19 09:28

The benefits of self-driving cars will likely make us want to drive more. Those extra miles could partially or completely offset any potential energy savings, research finds.

Previous studies have shown that greater fuel efficiency induces some people to travel extra miles, and those added miles can partially offset fuel savings—a behavioral change known as the rebound effect.

The ability to use time on the road productively in a self-driving car—work, sleep, watch a movie, read a book—will likely induce even more travel.

Taken together, those two sources of added mileage could partially or completely offset the energy savings that autonomous vehicles provide—and conceivably, even result in a net increase in energy consumption, a phenomenon known as backfire.

“The core message of the paper is that the induced travel of self-driving cars presents a stiff challenge to policy goals for reductions in energy use,” says coauthor Samuel Stolper, assistant professor of environment and sustainability at the School for Environment and Sustainability at the University of Michigan.

“Thus, much higher energy efficiency targets are required for self-driving cars,” says coauthor Ming Xu, associate professor of environment and sustainability at SEAS and associate professor of civil and environmental engineering at the College of Engineering.

For the paper, which appears in Applied Energy, researchers used economic theory and US travel survey data to model travel behavior and to forecast the effects of vehicle automation on travel decisions and energy use.

Most previous studies of the energy impact of autonomous vehicles focused exclusively on the fuel-cost component of the price of travel, likely resulting in an overestimation of the environmental benefits of the technology, researchers say.

In contrast, the new study looked at both fuel cost and time cost. The approach adapts standard microeconomic modeling and statistical techniques to account for the value of time.

The researchers estimate that the induced travel resulting from a 38 percent reduction in perceived travel time cost would completely eliminate the fuel savings associated with self-driving cars.

“Backfire—a net rise in energy consumption—is a distinct possibility if we don’t develop better efficiencies, policies, and applications,” says doctoral student Morteza Taiebat, lead author of the paper in Applied Energy.

The possibility of backfire, in turn, implies the possibility of net increases in local and global air pollution, the authors say.

Further, the researchers suggest there’s an equity issue that needs to be addressed as autonomous vehicles become a reality. The study found that wealthier households are more likely than others to drive extra miles in autonomous vehicles “and thus stand to experience greater welfare gains.”

The Dow Sustainability Fellows Program at the University of Michigan funded the work.

Source: University of Michigan

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To stop wasting fertilizer, find dud spots in corn fields

Fri, 2019-04-19 07:38

Big data can help corn farmers pinpoint specific parts of their fields that consistently produce either good or bad yields, research shows.

This will not only save them time and money, but also solve one of the most widespread environmental problems facing crop-producing regions—nitrogen loss.

“This is the first time anyone has been able to quantify how much small-scale yield variability there is in the United States Corn Belt,” says lead author Bruno Basso, professor of ecosystems science at Michigan State University.

“Our findings allow farmers to know exactly which portions of their farm fields have stable yields—which allows them to better manage their variable fields to save money, reduce fertilizer losses, and lower greenhouse gas emissions.”

Losing nitrogen, losing money

The researchers discovered that almost all fields have certain areas with consistently low or high yields, meaning much of the fertilizer added to low-yielding areas will go unused and be lost to the environment.

The study shows that lost nitrogen from 10 Midwest states totals nearly $1 billion of wasted fertilizer and 6.8 million metric tons of greenhouse gas emissions annually.

The research, which appears in Scientific Reports, is the first to quantify nitrogen losses from the low-producing areas of individual fields. Basso’s team used satellite imagery to measure eight years’ worth of sub-yield fields for 70 million acres of farmland in the Midwest. The analysis provided the researchers with a finely resolved image of the entire Midwest’s corn production, Basso says.

To validate the satellite imagery the team compared the satellite data against 10 years of high-resolution yield data sensors mounted on combine harvesters collected from more than 1,000 farms.

“We color-coded pixels in the images to see where the crop was stable and high-yielding, where it was stable and low-yielding and where it was unstable year-over-year,” Basso says.

“In total, about 50 percent of the subfield areas we analyzed were stable and high-yielding. The underperforming and the unstable areas each represented about 25 percent of total farmland.”

Focus on the high-yield fields

By assessing how much Corn Belt farmers spend on fertilizer that goes unused, the authors conclude that the best outcome—both for farmers and the environment—is to avoid fertilizing the underperforming areas of each field. In fact, Basso says, it may be better from an economic standpoint to leave these areas unfarmed, to plant them with conservation grasses, or in the future, with perennial bioenergy crops.

In any case, Basso says that time and resources should be focused on farming the portions of the fields that are high yielding or that are unstable—high yielding some years, low-yielding others. The unstable areas can be still be managed well with careful in-season management of nitrogen fertilizer, he says.

“By putting big data at the service of sustainability, we are now able to provide farmers with a prescription (Rx) map of nitrogen fertilizer for their fields, which can completely change how and where they focus their efforts,” Basso says.

“Farmers want to be good environmental stewards, and these findings give them an additional way to do so—to avoid over-fertilizing areas of fields that will lose the most nitrogen to groundwater, rivers, and streams. Nobody wins when fertilizer is wasted on areas that won’t produce. Once farmers identify these areas, they can both save money and help the environment.”

The researchers conducted the work at a variety of geographic scales, extending from small-scale research at the Kellogg Biological Station Long-Term Ecological Research site to individual farms in the region to ultimately the entire Midwest.


“The work demonstrates that overfertilization of consistently low-yield croplands is very costly to the industry and offers a valuable approach to meeting the farming industry goal of precision nitrogen management. Importantly, what’s best for farmers is also best for the environment,” says Colette St. Mary, a director of the National Science Foundation’s Long-Term Ecological Research program.

“The findings provide practical recommendations based on a convincingly complete data set coupled with remote sensing to persuade farmers that matching low crop yields from stable low-yield areas could eliminate seasonal excesses in reactive nitrogen,” says Jim Dobrowolski, National Program Leader for Water at USDA-NIFA.

The research “helps the farmer’s bottom line, while simultaneously reducing greenhouse gas emissions and maintaining water quality. It’s a ‘win-win-win’ solution.”

The US Department of Agriculture’s National Institute for Food and Agriculture, the US National Science Foundation’s Long-term Ecological Research and Dynamics of Coupled Natural and Human Systems Programs, the US Department of Energy’s Office of Science Division of Biological and Environmental Research, and Michigan State University AgBioResearch funded the research.

Source: Michigan State University

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When companies file an IPO, local ZIP codes get a boost

Fri, 2019-04-19 06:56

After a business files for an initial public offering, or IPO, communities with ZIP codes close to the company’s headquarters benefit, research finds.

Specifically, they see a rise in certain home prices and consumer spending—and creations of new businesses and jobs.

IPOs are not all good news for communities, however. The study also finds that IPO activity increases the odds that middle-to-lower-income residents may have to move to lower-income ZIP codes. In the years following Facebook’s IPO, for example, workers in the San Francisco Bay Area such as police officers, teachers, and firefighters were priced out of the housing market and relegated to long commutes to work.

“An IPO doesn’t create a new company,” says Alexander Butler, professor of finance at the Jones School at Rice University. “It does, however, generate significant liquidity for the firm, for employees, and for other shareholders who go forth into the community to spend their new cash.”

For the study, which appears in the Journal of Financial and Quantitative Analysis, researchers looked at 1,365 ZIP codes in which at least one company filed for an IPO between 1998 and 2015. They also identified ZIP codes two miles, five miles, and 10 miles from a newly public company’s headquarters. The team determined that the listing decision, rather than actual raising of capital, boosts local labor markets, business environments, consumer spending, and real estate.

“Investors’ wealth also rises if a firm’s stock price climbs after listing, as does a firm’s wealth as it raises new capital,” Butler says.

Businesses and jobs

To reach their conclusions, the researchers compared their selected ZIP codes to other ZIP codes in the same county using a matching process to compare “apples to apples.”

They compared figures such as changes in home prices, the number of new mortgages, ZIP code business patterns, credit card spending, and income and wages for the two years following an IPO.

An analysis of the data showed that when a company goes on the stock market, each $10 million in proceeds leads to an extra 0.7 new businesses in the surrounding area and 41 new local jobs.

And while the price of expensive homes in the new public company’s ZIP code didn’t increase, the prices of expensive homes in other ZIP codes within two miles of headquarters did—by $3,900 for the average home valued at $590,000. Prices also rose in ZIP codes two to five miles away from headquarters, but less so.

The growth of home prices gets a boost after the lockup period ends and shareholders can sell their stock, supporting the hypothesis that changes in investor liquidity cause that spillover. Further evidence of this came when they found that home prices climb even more when a firm’s stock price jumps after the IPO.


Coauthor Ioannis Spyridopoulos, assistant professor of finance at American University’s Kogod School of Business, says he and colleagues did the work, in part, to raise awareness of the positive side of finance.

“People have this demonized view of finance,” Spyridopoulos says. “They see and remember financial scandals. They think that finance is only about speculating and making profit in the short run, but they forget that finance is more than that.

“We need a well-functioning financial system. We need to have a functioning stock market that people trust and benefit from selling their stock quickly at a fair price. Our work shows why this liquidity is so important, by documenting positive economic effects in communities where people become flush with liquidity after their firms get listed in the stock market.

“It is an important reason why the US is the best economy in the world,” Spyridopoulos says. “We have the most developed financial system and a very good framework to protect it.”

Source: Rice University

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‘CSI’ conservation uses tiger spit and conch fritters

Thu, 2019-04-18 19:30

Scientists have come up with a new way to collect DNA from endangered species—extract it from degraded and left-behind materials, including feces, saliva, and even food products.

The near impossibility of collecting DNA samples from rare and elusive animals has hobbled wildlife detectives aiming to protect these endangered species. The researchers say their proof of concept, which appears in Methods in Ecology and Evolution, could revolutionize conservation approaches and policies worldwide.

“It’s CSI meets conservation biology,” says coauthor Dmitri Petrov, professor in the School of Humanities and Sciences at Stanford University.

Looming extinctions

The specter of extinction hangs over more than a quarter of all animal species, according to the best estimate of the International Union for Conservation of Nature, which maintains a list of threatened and extinct species. Conservationists have documented extreme declines in animal populations in every region of Earth.

“Conservation needs answers fast, and our research was not providing them fast enough.”

Helping species recover often depends on collecting DNA samples, which can reveal valuable information about details including inbreeding, population history, natural selection, and large-scale threats such as habitat destruction and illegal wildlife trade.

However, current approaches tend to require relatively large amounts of DNA or expensive and often inefficient strategies for extracting the material. Getting meaningful information rapidly from lower-concentration, often degraded and contaminated DNA samples requires expensive and specialized equipment.

Tigers and conchs

A solution may lie in an ongoing collaboration between Stanford’s Program for Conservation Genomics, including the labs of Petrov and coauthors Elizabeth Hadly and Stephen Palumbi, and India’s National Centre for Biological Sciences, including the lab of coauthor Uma Ramakrishnan, a molecular ecologist and former Fulbright faculty fellow at Stanford.

“I have been working on tiger conservation genetics for over a decade, but have been frustrated at how slow and unreliable the process of generating genetic data can be,” Ramakrishnan says. “Conservation needs answers fast, and our research was not providing them fast enough.”

The researchers looked at endangered wild tigers in India and overfished Caribbean queen conchs, examining tiger feces, shed hair, and saliva found on killed prey, as well as fried conch fritters purchased in US restaurants. All of the samples were too impure, mixed, or degraded for conventional genetic analysis.

“Our goal was to find extremely different species that had strong conservation needs, and show how this approach could be used generally,” says Palumbi, professor of marine biology. “The King of the Forest—tigers—and Queen of the Caribbean—conch—were ideal targets.”

Tiny bits of DNA

Together, the team improvised a new approach, using a sequencing method that amplifies and reads small bits of DNA with unique differences in each sample. Doing this simultaneously across many stretches of DNA in the same test tubes allowed the researchers to keep the total amount of DNA needed to a minimum.

Making the procedure specific to tiger and conch DNA allowed for the use of samples contaminated with bacteria or DNA from other species.

The technology proved highly effective at identifying and comparing genetic characteristics. For example, the method worked with an amount of tiger DNA equivalent to about one-one-hundred-thousandth the amount of DNA in a typical blood sample. The method had a higher failure rate in conchs because the researchers did not have whole genomes at their disposal.

The approach’s effectiveness, speed and affordability—implementation could cost as little as $5 per sample—represents a critical advance for wildlife monitoring and forensics, field-ready testing, and the use of science in policy decisions and wildlife trade, the researchers say.

“It is easy to implement and so can be done in labs with access to more or less basic equipment,” says coauthor Meghana Natesh of the National Centre for Biological Sciences and Sastra University in India. “If a standard procedure is followed, the data generated should be easy to share and compare across labs. So monitoring populations across states or even countries should be easier.”

The scientists have made their methods freely available. “We are working to expand the method so that it can identify other species and other characteristics, such as diet and pathogens,” Hadly says.

The Wildlife Conservation Trust, the US Department of State, the Wellcome Trust / DBT India Alliance, the Summit Foundation, and the Smithsonian Institution funded the work, which appears in
Methods in Ecology and Evolution.

Source: Stanford University

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Rain on other side of the planet foreshadows California heat

Thu, 2019-04-18 18:50

When heavy rain falls over the Indian Ocean and Southeast Asia and the eastern Pacific Ocean, it is a good indicator that temperatures in central California will reach 100°F in four to 16 days, according to new research.

Heat waves are common in California’s Central Valley, a 50-mile-wide oval of land that runs 450 miles from just north of Los Angeles up to Redding. The valley is home to half of the nation’s tree fruit and nut crops, as well as extensive dairy production, and heat waves can wreak havoc on agricultural production. The dairy industry had a heat wave-induced economic loss of about $1 billion in 2006, for instance. The ability to predict heat waves and understand what causes them could inform protective measures against damage.

“We want to know more about how extreme events are created,” says corresponding author Richard Grotjahn, professor in the land, air, and water resources department at the University of California, Davis.

“We know that such patterns in winter are sometimes linked with areas of the tropics where thunderstorms are enhanced. We wondered if there might be similar links during summer for those heat waves.”

The scientists analyzed the heat wave data from June through September from 1979 to 2010. Fifteen National Climatic Data Center stations located throughout the valley collected the data. From these data, the researchers identified 24 heat waves. They compared these instances to the phases of a large, traveling atmospheric circulation pattern called the Madden-Julian Oscillation, or MJO.

The MJO manifests as heavy rain that migrates across the tropical Indian and then Pacific oceans, and researchers have shown that it influences winter weather patterns.

“It’s well known that tropical rainfall, such as the MJO, has effects beyond the tropics,” says the paper’s first author Yun-Young Lee of the Asia-Pacific Economic Cooperation Climate Center in Busan, South Korea. “So a question comes to mind: Is hot weather in the Central California Valley partly attributable to tropical rainfall?”

Lee and Grotjahn found that, yes, enhanced rainfall in the tropics preceded each heat wave in specific and relatively predictable patterns. They also found that hot weather in the valley is most common after more intense MJO activity in the eastern Pacific Ocean, and next most common after strong MJO activity in the Indian Ocean.

“The more we know about such associations to large-scale weather patterns and remote links, the better we can assess climate model simulations and therefore better assess simulations of future climate scenarios,” Grotjahn says.

The National Science Foundation, the National Aeronautics and Space Administration, the Department of Energy Office of Science, the United States Department of Agriculture’s National Institute of Food and Agriculture, and the APEC Climate Center in the Republic of Korea funded the research.

The work appears in Advances in Atmospheric Sciences.

Source: UC Davis

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We finally know how general anesthesia works

Thu, 2019-04-18 18:44

In a new study,researchers found that to knock you out, different anesthesia drugs hijack the neural circuitry that makes you fall sleep.

The discovery of general anesthesia 170 years ago was a medical miracle, enabling millions of patients to undergo invasive, life-saving surgeries without pain.

General anesthesia drugs induce unconsciousness by activating a tiny cluster of cells at the base of the brain called the supraoptic nucleus (shown in red), while the rest of the brain remains in a mostly inactive state (blue). (Credit: Duke)

For the study, which appears in Neuron, researchers traced this neural circuitry to a tiny cluster of cells at the base of the brain responsible for churning out hormones to regulate bodily functions, mood, and sleep.

The finding is one of the first to suggest a role for hormones in maintaining the state of general anesthesia, and provides valuable insights for generating newer drugs that could put people to sleep with fewer side effects.

Ever since the first patient went under general anesthesia in 1846, scientists have tried to figure out exactly how it works. The prevailing theory was that many of these drugs tamp down the brain’s normal activities, resulting in the inability to move or feel pain.

Similar theories revolved around sleep, the sister state to general anesthesia. However, research over the last decade has shown that sleep is a more active process than previously recognized, with entire sets of neurons clocking in to work while you catch your Z’s.

Fan Wang, a professor of neurobiology at Duke University School of Medicine, and Li-Feng Jiang-Xie, a graduate student in her laboratory, wondered whether the predominant view of general anesthesia was also one-sided.

“Perhaps rather than simply inhibiting neurons, anesthetics could also activate certain neurons in the brain,” says Jiang-Xie.

To test their new theory, Jiang-Xie and Luping Yin, a postdoctoral fellow in the Wang lab, put mice under general anesthesia with several different but commonly used drugs. Then they used molecular markers to track down the neurons commonly activated by the anesthetics.

They found a cluster of actively firing neurons buried in a tiny brain region called the supraoptic nucleus, known to have leggy projections that release large amounts of hormones like vasopressin directly into the bloodstream.

“Most of the anesthesia-activated cells were a kind of hybrid cell that connects the nervous system and the endocrine system,” says Jiang-Xie. “That took us by surprise and led us into unexplored territory for understanding the neural pathways of general anesthesia.”

Next, the researchers tapped a sophisticated technique developed in the Wang lab to turn on or off this specialized group of cells with chemicals or light. When they switched on the cells in mice, the animals stopped moving and fell into a deep slumber called slow wave sleep, typically associated with unconsciousness.

Then the research team killed off this group of cells. The mice continued to move around, unable to fall asleep.

Finally, the researchers performed similar experiments on mice under general anesthesia. They found that artificially pre-activating the neuroendocrine cells made the mice stay under general anesthesia for longer periods of time. Conversely, when they silenced these cells, the mice woke up from anesthesia more easily.

The study also revealed a previously unexpected role of the brain’s hormone-secreting cells in promoting deep sleep.

“Many people, particularly those with Alzheimer’s disease, have difficulty falling to sleep, yet current medications have troublesome side effects,” says Yin. “If we can find ways to manipulate this neural circuitry, perhaps by targeting hormones or small peptides, then it could lead to the development of better sleeping pills.”

The W.M Keck Foundation, the Brain Research Foundation, the National Institutes of Health, and a Human Frontier Science Fellowship funded the work.

Source: Duke University

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System restores some pig brain function hours after death

Thu, 2019-04-18 18:33

Researchers restored circulation and cellular activity in a pig’s brain four hours after its death, the team reports.

The finding challenges long-held assumptions about the timing and irreversible nature of the cessation of some brain functions after death.

Researchers isolated the brain of a postmortem pig from a meatpacking plant and circulated a specially designed chemical solution. They observed many basic cellular functions once thought to cease seconds or minutes after oxygen and blood flow cease, the scientists report.

“The intact brain of a large mammal retains a previously under-appreciated capacity for restoration of circulation and certain molecular and cellular activities multiple hours after circulatory arrest,” says senior author Nenad Sestan, professor of neuroscience, comparative medicine, genetics, and psychiatry at Yale University.

Immunofluorescent stains for neurons (green), astrocytes (red), and cell nuclei (blue) in a region of the hippocampus of a pig’s brain left untreated 10 hours after death (left) or subjected to perfusion with the BrainEx technology. Ten hours postmortem, neurons and astrocytes undergo cellular disintegration unless the BrainEx system salvages them. (Credit: Stefano G. Daniele & Zvonimir Vrselja; Sestan Laboratory; Yale School of Medicine)

Researchers also stress, however, that the brain lacked any recognizable global electrical signals associated with normal brain function.

“At no point did we observe the kind of organized electrical activity associated with perception, awareness, or consciousness,” says co-first author Zvonimir Vrselja, associate research scientist in neuroscience.

“Clinically defined, this is not a living brain, but it is a cellularly active brain.”

The nature of death

Scientists usually consider cellular death within the brain a swift and irreversible process. Cut off from oxygen and a blood supply, the brain’s electrical activity and signs of awareness disappear within seconds, while energy stores are depleted within minutes. Current understanding maintains that a cascade of injury and death molecules activate, leading to widespread, irreversible degeneration.

However, researchers in Sestan’s lab, whose research focuses on brain development and evolution, observed that the small tissue samples they worked with routinely showed signs of cellular viability, even when the tissue was harvested multiple hours postmortem.

Intrigued, they obtained the brains of pigs processed for food production to study how widespread this postmortem viability might be in the intact brain. Four hours after the pig’s death, they connected the vasculature of the brain to circulate a uniquely formulated solution they developed to preserve brain tissue, utilizing a system they call BrainEx. They found the system preserved neural cell integrity, and restored certain neuronal, glial, and vascular cell functionality.

Why it matters

The new system can help solve a vexing problem—the inability to apply certain techniques to study the structure and function of the intact large mammalian brain—which hinders rigorous investigations into topics like the roots of brain disorders, as well as neuronal connectivity in both healthy and abnormal conditions.

“Previously, we have only been able to study cells in the large mammalian brain under static or largely two-dimensional conditions utilizing small tissue samples outside of their native environment,” says co-first author Stefano G. Daniele, an MD/PhD candidate.

“For the first time, we are able to investigate the large brain in three dimensions, which increases our ability to study complex cellular interactions and connectivity.”

While the advance has no immediate clinical application, the new research platform may one day be able to help doctors find ways to help salvage brain function in stroke patients, or test the efficacy of novel therapies targeting cellular recovery after injury, the authors say.

“This line of research holds hope for advancing understanding and treatment of brain disorders and could lead to a whole new way of studying the postmortem human brain,” says Andrea Beckel-Mitchener, chief of functional neurogenomics at the NIH’s National Institute of Mental Health, which co-funded the research.

Ethical standards

The researchers says that it is unclear whether this approach can be applied to a recently deceased human brain. The chemical solution used lacks many of the components natively found in human blood, such as the immune system and other blood cells, which makes the experimental system significantly different from normal living conditions. However, the researchers stress that any future study involving human tissue or possible revival of global electrical activity in postmortem animal tissue should be done under strict ethical oversight.

“Restoration of consciousness was never a goal of this research,” says coauthor Stephen Latham, director of Yale’s Interdisciplinary Center for Bioethics. “The researchers were prepared to intervene with the use of anesthetics and temperature-reduction to stop organized global electrical activity if it were to emerge. Everyone agreed in advance that experiments involving revived global activity couldn’t go forward without clear ethical standards and institutional oversight mechanisms.”

There is an ethical imperative to use tools developed by the Brain Initiative to unravel mysteries of brain injuries and disease, says Christine Grady, chief of the Department of Bioethics at the NIH Clinical Center.

“It’s also our duty to work with researchers to thoughtfully and proactively navigate any potential ethical issues they may encounter as they open new frontiers in brain science,” she says.

The research appears in Nature. The National Institutes of Health’s BRAIN Initiative funded the research.

Source: Yale University

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Can ginkgo biloba seeds fight skin infections?

Thu, 2019-04-18 12:05

Extracts from the seeds of the Ginkgo biloba tree show antibacterial activity on pathogens that can cause skin infections such as acne, psoriasis, dermatitis, and eczema, a new study finds.

The findings show that the extracts inhibit the growth of Cutibacterium acnes, Staphylococcus aureus, and Streptococcus pyogenes.

A nearly 200-year-old copy of a 16th-century text on traditional Chinese medicine, the Ben Cao Gang Mu, guided the researchers in their experiments.

“It was like blowing the dust off knowledge from the past and rediscovering something that had been there all along,” says co-first author of the paper Xinyi (Xena) Huang.

Huang, a native of China, began the project for her senior thesis as a biology major at Emory University. She is now a student at the University of Maryland School of Pharmacy.

‘Complex chemistry’

“To the best of our knowledge, this is the first study to demonstrate the antibacterial activity of ginkgo seeds on skin pathogens,” says Cassandra Quave, senior author of the paper and assistant professor at Emory’s Center for the Study of Human Health and the dermatology department at the School of Medicine.

“This paper is just one more example of how much we still have to learn about the pharmacological potential of the complex chemistry of plants.”

Quave is an ethnobotanist, studying how indigenous people use plants in their healing practices, to uncover promising candidates for new drugs.

“Our results give validity to the use of ginkgo seeds as a topical antimicrobial as prescribed in this 16th-century text,” says co-first author Francois Chassagne, a pharmacist in the Quave lab.

Many hurdles remain, he adds, before scientists can consider ginkgo seed extracts for use in a modern-day medical context. In its concentrated form, the main compound that a statistical analysis identified as likely responsible for the antibacterial activity, ginkgolic acid C15:1, has been demonstrated to have skin toxicity.

“One possible strategy in the search for new antibiotics would be to investigate ways to modify the structure of the particular ginkgolic acid tied to the antibacterial activity, to try to improve its efficacy and also to reduce its toxicity to human skin cells,” Chassagne says.

The ginkgo biloba, which is native to China, is one of the oldest tree species, going back at least 270 million years. The tree has distinctive fan-shaped leaves and a long history in traditional Chinese medicine.

Modern-day researchers have studied ginkgo extensively in search of medical benefits for everything from memory enhancement to macular degeneration, but there is still “no conclusive evidence that ginkgo is helpful for any health condition,” according to the web page of the National Institutes of Health’s National Center for Complementary and Integrative Health. Most previous studies have focused on the ginkgo leaves.

A seed of inspiration

During her first year at Emory, Huang began volunteering in the Emory Herbarium, where she processed medicinal herbs that Quave collected in the Mediterranean. She eventually joined the Quave lab, due to her interest in pharmacy.

When walking across campus, pondering what to focus on for her senior thesis, a ginkgo tree caught Huang’s eye. She knew that the tree was used in traditional Chinese medicine, although she did not know any details, so she decided to research it.

Huang’s interest grew when she learned that Emory has an 1826 version of the Ben Cao Gang Mu, or Compendium of Materia Medica. Considered the most comprehensive book on traditional Chinese medicine, Li Shi-zhen compiled and wrote the book in the 16th century during the heyday of the Ming Dynasty. The original compendium is vast, encompassing dozens of volumes, but Huang had only seen greatly condensed versions sold in Chinese bookstores.

The copy Huang read resides in the Candler School of Theology’s Pitts Theology Library. The 1826 version passed at one stage through a London book dealer. The unnumbered pages contain block-printed in Chinese characters, but at some point someone rebound them into 10 volumes with covers labeled in English.

The Ben Cao Gang Mu arrived at Emory as part of the university’s purchase of more than 200,000 volumes from Hartford Theological Seminary in 1975.

“At the time, it was the largest transfer of a book collection ever between academic libraries,” says Brandon Wason, above, curator of archives and manuscripts at Pitts Theology Library.

Touching history

Huang never imagined she would be touching such an old copy of the Ben Cao Gang Mu.

“You can feel the history in it,” she says. “The paper is so yellow, thin and fragile that I was afraid I would break the pages as I was turning them.”

In a volume labeled “Grains, Vegetables, Fruits,” Huang found references to the uses of ginkgo, written in an engaging, narrative style. The book described 17 traditional uses for the seed, including eight for skin disorders such as chapped hands and feet, rosacea, crab louse-induced itchiness, dog-bit wound abscesses, and pustules.

Li Shi-Zhen recommended preparing a paste of ground up seeds mixed with rice wine or other alcohol, or by immersing the crushed seeds in rape seed oil. The paste could then be applied to the affected area.

“I was surprised because I had never thought about doing anything with gingko seeds except eating them,” Huang says. “I remember the first time I tasted them was in Cantonese soup. The seed turns an unforgettable bright yellow when it’s cooked. The flavor is really distinct—a little bit bitter but also sweet. They’re good, but my parents warned me not to eat more than five at a time.”

The Ben Cao Gang Mu, she learned as she read it, also advised limiting consumption of the seeds.

The past and the present

A previous study found that ginkgo seed coats demonstrated antibacterial activity against some intestinal bacterial pathogens. And ginkgo leaves have shown antibacterial activity on both some intestinal bacteria and on the skin pathogen S. aureus.

Huang, however, wanted to test the information she had gleaned from the ancient text for the use of ginkgo seeds as a topical treatment for skin disorders. Skin pathogens are of particular interest to the Quave lab, which focuses on finding new approaches to treat antibiotic-resistant bacteria.

Huang gathered ginkgo samples from trees on campus, including seeds and immature whole seeds. She purchased additional fresh seeds from a local farmer’s market for the research and obtained nine chemicals known to be in ginkgo from chemical suppliers in their pure form.

The researchers processed the extractions from the seeds as closely as possible to the recommendations of the Ben Cao Gang Mu, using either water, ethanol, or rape seed oil. Huang and Chassagne conducted microbial experiments—including the evaluation of ginkgo extracts from the seed nut, immature seeds, and the seed coat—on 12 different bacterial strains.

The results showed that the ginkgo seed coats and the immature seeds exhibited antibacterial activity on three of the strains tested: C. acnes, S. aureus, and S. pyogenes. Statistical analysis also found a positive correlation between the antimicrobial activity of the ginkgo samples and the concentration of ginkgolic acid C15:1, suggesting it was involved in the activity.

“Our finding is still in a basic, benchtop phase—these extracts have not yet been tested in animal or human studies—but it is still a thrill for me to learn that this ancient story in the Ben Cao Gang Mu appears to be real,” Huang says. “As a student pharmacist, this gives me more appreciation for the value of using ancient plant remedies to guide modern-day research.”

The research appears in Frontiers in Microbiology.

Source: Emory University

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Sea snake and elephant skin have a trick in common

Thu, 2019-04-18 10:57

Both elephants and yellow-bellied sea snakes have skin that can create a water sheath around the animal, research finds.

In addition, sea snake skin has evolved to permit the animal to thrive as the only pelagic species of venomous sea snake. (Pelagic refers to species residing in the open sea.)

The new study, published in the Journal of Morphology, is the first to quantify the water-retention capacity of sea snake skin, which is crucial to their ability to rest on the surface of the ocean to bask and travel great distances oversea without drying out.

A yellow-bellied sea snake (Hydrophis platurus). (Credit: Mark Sandfoss/U. Florida)

Squamates (snakes and lizards) have a thicker, cornified outer layer of skin called the stratum corneum that allows them to thrive in many arid or semi-arid environments. The stratum corneum includes a lipid- and keratin-based permeability barrier. Yet Hydrophis platurus has an unusual skin structure.

To support H. platurus’ ability to move between the ocean’s surface and depths, the outer keratin level is thinner to allow for improved respiratory gas exchange in the skin. The skin also includes filamentous receptors that permit the snake to detect nearby prey and even help distinguish freshwater from seawater.

“I realized from natural history and photographs of elephants that the superficial structure of the skin had similarities with that of toads, and that both animals used capillary attraction forces to help wet the skin and keep the superficial epidermis from drying,” says Harvey Lillywhite, professor of biology at the University of Florida.

“Elephants wallow when they can find water holes, and the adaptive function of the sculptured surfaces is similar to that of toads that were studied previously.”

The sea snake species’ enormous range takes it across the Indo-Pacific Oceans, and it moves between the surface of the water down to depths of 50 feet. According to Lillywhite, because of this unusual habitat, its skin has some distinct features, including furrows along its scales, as opposed to the overlapping morphology of other snakes’ scales.

These furrows collect water and form a sheath around the snake. A similar structure is evident in elephant skin. Indeed, this research shows that the meso layer of H. platurus’ skin features a “brick and mortar” organization of lipids that is closer to mammalian skin and is markedly different from most squamates’ skin.

Moreover, to keep from drying out while constantly immersed in seawater, sea snake skin actively creates lipids to enhance the permeability barrier. This increased production of lipids to keep the skin hydrated is unusual among squamates, including other species of sea snakes, but has parallels to the skin of cetaceans (dolphins and whales).

Lillywhite’s coauthor, Gopinathan Menon from the California Academy of Sciences, says, “We get an evolutionary insight into what preceded the development of mammalian skin barrier, what pre-adaptations allowed the mammals to go back into an aquatic life as mammals and birds evolved from reptiles.”

Source: University of Florida

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Morphing origami could lead to better concert halls and drones

Thu, 2019-04-18 09:48

A new type of origami can morph from one pattern to another—or even a hybrid of two patterns—instantly altering many of its structural characteristics.

The research could unlock new types of origami-based structures or metamaterials that leverage the characteristics of two types of origami.

Scientists have used origami-based structures to create deployable solar arrays for space, adaptable acoustic systems for symphony halls, and even crash protection systems for flying drones.

“This hybrid origami allows for reprogrammable mechanical properties and the ability to change those properties while the material is in service,” says Glaucio Paulino, a professor in the School of Civil and Environmental Engineering at Georgia Tech.

(Credit: Allison Carter)

The researchers started with two types of origami patterns: the Miura-ori and the eggbox, both of which can form into sheets of repeating patterns. The Miura-ori looks like rows of folded zigzags, while the eggbox pattern resembles a mountain range with repeating peaks and valleys.

Both can compress into a very small space, but when expanded behave differently from one another in how they respond to bending. The eggbox pattern resembles a dome when bent, and the Miura-ori takes the shape of a saddle.

“Traditionally, if you have an eggbox pattern, you are locked into the characteristics of that particular pattern,” Paulino says. “With this new pattern, which we are calling morph, that’s no longer the case.”

A redesign of the geometry of two of the four planes that comprise one section of the origami allows the new pattern to achieve its morphing ability. Shrinking the two planes on one side enables their creases to shift from a mountain to a valley, or in other words, to fold in the opposite direction.

And importantly, the transition from peak to valley can occur whether the origami forms from a flexible material such as paper or a rigid material such as metal.

That means, for example, that origami-based structures used for acoustic systems—which can already expand and contract to increase or decrease the volume of the sound response—could go one step further, changing how they bend to potentially offer an even greater range of resonant responses.

In the example of the drone crash protection system, the new origami pattern could potentially offer other customization options or alter aspects of its impact resistance, Paulino says.

The new origami pattern can also take on a hybrid structure, where certain rows fold into one configuration and others fold in the other. In such a configuration, the structure would exhibit characteristics of both types.

“There are a large number of combinations in terms of how these could be configured, which offers a lot of customization possibilities for structures based on the morph pattern,” says Ke Liu, a postdoctoral scholar at the California Institute of Technology.

Another unique characteristic of the morph pattern happens when a Miura-ori row lies between two eggbox rows. Typically, when tension pulls apart either of the patterns, they give in and flatten their shape. However, in this new instance, the Miura-ori pattern locks into place.

“The locking is very strong, and there is no way to break that hold other than to tear the entire structure apart,” says Phanisri Pratapa, an assistant professor of civil engineering at the Indian Institute of Technology Madras.

The locking could enable structures to limit the amount of expansion possible and change that limit on the fly, Pratapa says.

The research appears in Physical Review Letters. The National Science Foundation and the Raymond Allen Jones Chair at Georgia Tech supported the work.

Source: Georgia Tech

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Quick learners have speedier neurons

Thu, 2019-04-18 09:43

The speed with which a person is able to grasp, process, understand, store, and use information comes down to the speed and timing with which the neurons in the brain fire off, research finds.

The closer the gap between the firing of one neuron and the next, the greater the speed with which they receive the information, store it, and act upon it.

In other words, when it comes to quick thinking, timing makes all the difference. The research  provides fundamental information about the precise timing that can critically affect the formation of memory processes.

Snappy synapses

The capacity to adapt and learn with experience is one of the most intriguing features of the human brain. This fascinating organ is composed of billions of neurons, which are in turn connected to many other cells. The physical connections between neurons, called synapses, are where neurons communicate with each other.

Synapses are remarkably plastic—these connections can strengthen or weaken dynamically in response to incoming information. Such changes in the efficacy of the synapses underlie learning and the formation of memory in the brain.

Researchers at NUS Yong Loo Lin School of Medicine found that neurons in the hippocampus, a brain region critical for the formation of memory, use a surprisingly wide variety of learning mechanisms. One such form of learning, termed “spike-timing-dependent plasticity (STDP),” depends on the timing of each pair of electrical spikes (electrical activity used to transmit information within neurons) in the pre-synaptic neuron and the post-synaptic neuron. An electrical spike in the presynaptic neuron stimulates the neuron to release neurotransmitters, which travel across the synapse to activate the postsynaptic neuron, where it converts information back into an electrical spike.

When the pre- and postsynaptic neurons are active at the same time (less than 30 milliseconds apart), the connections between them strengthen. However, when the presynaptic neuron fires earlier by 30 milliseconds or more, or when the postsynaptic neuron fires earlier by more than 10 milliseconds, the connections strengthen to a lesser degree.

In addition, the researchers demonstrated that when the pre- and postsynaptic spikes occur at the same time, the increase in synaptic strength persists for several hours, and the synapse can even strengthen weak information so that it gets stored. The effect was specific, working only to strengthen this synapse, not to enhance changes in other synapses. This study reveals how important the split-second timing in neuronal activity is in shaping information processing in the brain.

The researchers could detect the longer-term effects of the inter-spike timing because they studied the synaptic changes for a longer duration (4 hours) than previous studies, which were typically less than 1.5 hours.

The STDP model has been proposed to explain spatial and temporal sequence learning. Moreover, the STDP model comes in handy in various situations where object identification and decision-making have to be done quickly, e.g. projectile avoidance or friend-foe identification.

For instance, when a ball is flying towards us, we have to identify the object and its trajectory of travel within a very small window of time, in order to swiftly take action to avoid being hit. Similarly, when we come across another person, we have to quickly decide whether they are a friend or a foe. And this recognition requires the coordinated action of various areas of the brain within an activity timing window explained by STDP.

Timing is everything

“Unfortunately, the ability for the brain to change in response to such precise timing of information flow may be lacking in brains affected by Alzheimer’s disease as the hippocampus is particularly damaged in this common cause of dementia,” says Christopher Chen, senior consultant neurologist at National University Hospital and director of the Memory Aging and Cognition Centre in the National University Health System.

“This study may provide the foundation for understanding how such timing differences alter brain function and also how these changes could be reversed or mitigated. This might enable clinicians to help patients who suffer from memory loss.”

A comprehensive understanding of the factors that shape neural connections is critical for our understanding of information processing in the brain. It also helps us to understand how memories form. Furthermore, a firm grasp of these neural computational rules can help guide the building of artificial intelligence technology, e.g. deep neural networks, which take inspiration from the brain’s learning mechanisms.

“In the case of Autism Spectrum Disorder, some of the neural systems are more active than the others. This could be the reason why some autistic people are good at certain tasks like arts or mathematics, but have difficulty socializing. Using artificial intelligence, it might be possible to identify the neural networks that are more or less active and it might be possible to normalize their functioning using STDP rules,” says Sajikumar Sreedharan of the physiology department of the National University of Singapore.

Based on this improved understanding of how normal brains compute information and learn, researchers can identify mechanisms for further study that may be involved in conditions like schizophrenia, depression, sleep loss, stroke, chronic pain, learning disability, and Alzheimer’s disease.

The study appears in the Proceedings of the National Academy of Sciences.

Source: National University of Singapore

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Same-sex couples 73% more likely to get mortgage denial

Thu, 2019-04-18 09:24

Mortgage lenders are less likely to approve same-sex couples, research finds.

Researchers in Iowa State University’s Ivy College of Business analyzed national mortgage data from 1990 to 2015 and found the approval rate for same-sex couples was 3 to 8 percent lower. The study also includes a smaller dataset with more detail about applicants’ work history and credit worthiness.

Based on this data, same-sex applicants were 73 percent more likely to get a denial than heterosexual couples.

Same-sex couples who were approved paid more in interest and fees. Coauthors Hua Sun and Lei Gao, associate and assistant professors of finance, respectively, say the difference in finance fees averaged less than .5 percent, but combined added up as much as $86 million annually.

The research, published in the Proceedings of the National Academy of Sciences, found no evidence that same-sex couples had a higher default risk.

“Lenders can justify higher fees, if there is greater risk,” Gao says. “We found nothing to indicate that’s the case. In fact, our findings weakly suggest same-sex borrowers may perform better.”

Equal access to credit

While mortgage applicants are not required to disclose their sexual orientation, the researchers say perception is just as damaging in terms of discrimination. The Fair Housing and Equal Credit Opportunity acts prohibit discrimination based on a borrower’s race, gender, marital status, or religion, but neither specifically lists sexual orientation.

The researchers say the findings illustrate a need for change to make the law fair for everyone. Loan decisions should be based on fundamental economic factors, not skin color, sexual orientation, or gender. Sun says making sexual orientation a protected class would limit potential discrimination.

“Policymakers need to guarantee same-sex couples have equal access to credit,” Sun says. “Using our framework, credit monitoring agencies also can take steps to investigate unfair lending practices.”

Neighborhood effects

Sun and Gao used data from the Home Mortgage Disclosure Act, the Federal Reserve Bank of Boston, and Fannie Mae Loan Performance to test whether perceived sexual orientation affected mortgage approval, cost, and performance. Using these datasets allowed researchers to validate their findings and control for factors such as income, variations in lenders’ underwriting standards, and property type, which may influence approval rates.

Co-applicants of the same gender were identified as same-sex couples for the study. The researchers used Gallup and Census Bureau data of geographic distributions of LGBT adults to verify their identification strategy and reported a good matching quality.

Previous research has shown that recent home purchases or refinancing in a neighborhood can predict defaults, which influences mortgage lending approval and interest rates. To determine if the percentage of LGBT individuals living in a neighborhood contributed to the disparity in approval rates, Sun and Gao looked at county-level percentages of same-sex applicants each year.

What they found was somewhat surprising. In neighborhoods with more same-sex couples, both same-sex and different-sex borrowers seem to experience more unfavorable lending outcomes overall. The researchers say the findings should raise enough concern to warrant further investigation.

Source: Iowa State University

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Stress doesn’t stop male lizards from showing off

Thu, 2019-04-18 08:11

The physical traits and behaviors that lizards use to attract potential mates and fend off competitors may be so important that they don’t change in the face of stress.

A new study shows that low levels of stress-associated hormones don’t affect the blue and black badges on the throats and abdomens of male fence lizards—or the signaling behaviors used to show them off.

“Animals in the wild experience stress every day when they flee from predators, fight with others over food, or face extreme weather,” says Kirsty MacLeod, a postdoctoral scholar at Penn State at the time of the research and lead author of the paper, which appears in Scientific Reports.

“But they are facing increasing amounts of stress due to increased interactions with people, a changing climate, and other anthropogenic changes. Because of this, it is rapidly becoming more important to understand the myriad effects of stress on population health.”

Billboard ads

The researchers studied the effects of stress on “secondary sexual traits,” which, like a deer’s antlers or a bird’s brilliant colors, are important in attracting mates or warding off potential rivals, and ultimately contribute to an animal’s ability to reproduce.

Specifically, they studied the blue and black badges that appear on the throats and abdomens of male eastern fence lizards.

“Secondary sexual traits are the billboard ads animals use to advertise their condition,” MacLeod says. “Being more colorful or having bigger ornaments—like antlers—than your neighbor, could mean the difference between mating and passing on your genes, or not mating at all.

“They also help in maintaining a great territory that can provide resources for your offspring and preventing constant attack by rival males. If stress affects these secondary sexual traits, it could affect which individuals are successful in mating or holding territories, which could in turn affect the evolution and persistence of these populations—even though these traits are often not thought of as being central to population health.”

The researchers found that the color of a lizard’s badges is not related to the normal circulating levels of the stress hormone corticosterone in their blood. Additionally, artificially elevating levels of corticosterone, replicating the elevation that occurs when a lizard encounters a stressor like a predator, repeatedly over the course of a few weeks did not affect badge color.

Lizard push-ups

In addition to investigating the physical trait of badge color, the research team also looked at how the trait is displayed through behaviors. Much like a male peacock might raise its colorful tail, fence lizards perform push-ups and bob their heads to show off their badges, warding off other males or attracting potential mates.

“If stress did not affect color but did affect the behavior, for example if lizards stopped doing push-ups, then it wouldn’t matter if their color was the same because it wouldn’t be seen,” MacLeod says. “It would be like having a big flashy billboard lying on the ground.”

Elevating stress hormones did not affect signaling behaviors, including the number of push-ups or head bobs that the lizards performed, the researchers found.

“We know that elevating stress hormones can have important effects in this lizard species, including on immune function and behaviors that allow them to deal with predators, so these results are particularly interesting,” says Tracy Langkilde, professor and head of biology and senior author of the paper.

“It may be that low-level stress is not enough to impact these traits. Or that sexual signaling—to find better mates and maintain better territories—is so important that, when lizards experience stress, more resources are allocated to maintain them.”

Negative results

Next, the researchers plan to investigate whether maintaining these signaling traits under stress has an increased physiological cost on other aspects of lizard health and survival.

Sharing negative results like these, which show that a factor of interest does not have an effect, provide meaningful information and can challenge the status quo, the researchers say.

“It’s always cool to show that something you expected to have an impact on animals, like stress, does so, but it’s equally important to show where there is no impact,” MacLeod says.

“If we only reported results that show stress having an impact, we might over-estimate the effects of stress. Our results suggest that animals are resilient to stress where it matters: in the context of sexual signaling, which is likely to be critical in determining their ability to successfully reproduce.”

Gail McCormick, a graduate student at Penn State at the time of the research and currently a research fellow at Lund University in Sweden, contributed to the research, which received funding from the National Science Foundation and the Society of Ichthyologists and Herpetologists.

Source: Penn State

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A new kind of signal points to neutron star mergers

Thu, 2019-04-18 07:34

NASA’s Chandra X-ray Observatory has discovered a bright burst of X-rays in a galaxy 6.6 billion light years from Earth.

This event likely signaled the merger of two neutron stars—dense stellar objects packed mainly with neutrons—and could give astronomers fresh insight into how neutron stars are built.

When two neutron stars merge they produce jets of high-energy particles and radiation fired in opposite directions. If the jet is pointed along the line of sight to Earth, astronomers can detect a flash, or burst, of gamma rays. If the jet is not pointed in our direction, a different signal is necessary to identify the merger, such as the detection of gravitational waves—ripples in space time.

Now, with the observation of a bright flash of X-rays, astronomers have found a different kind of signal that could indicate a merger, and discovered that two neutron stars likely merged to form a new, heavier, and fast-spinning neutron star with an extraordinarily strong magnetic field.

A bright burst of X-rays that NASA’s Chandra X-ray Observatory discovered likely signals the merger of two neutron stars— dense stellar objects packed mainly with neutrons. The source of the X-rays, dubbed XT2, is located in the Chandra Deep Field South (CDF-S), a small patch of sky in the Fornax constellation. The wider field of view shows an optical image from the Hubble Space Telescope of a portion of the CDF-S field, while the inset shows a Chandra image focusing only on XT2. (Credit: X-ray: NASA/CXC/U. of Science and Technology of China/Y. Xue et. al.; Optical: NASA/STScI)

“We’ve found a completely new way to spot a neutron-star merger,” says Yongquan Xue, professor at the University of Science and Technology of China (USTC) and lead author of the paper; Xue was formerly a postdoctoral researcher at Penn State.

“The behavior of this X-ray source matches what one of our team members predicted for these events.”

XT2 discovery

Chandra observed the source, dubbed XT2, as it suddenly appeared and then faded away after about seven hours. The source is in a region of the sky known as the Chandra Deep Field-South, which is the focus of the deepest X-ray image ever taken, containing almost 12 weeks of Chandra observing time taken at various intervals over nearly 16 and a half years. XT2 appeared on March 22, 2015, and scientists discovered it later in analysis of archival data.

“The serendipitous discovery of XT2 makes another strong case that nature’s fecundity repeatedly transcends human imagination,” says coauthor Niel Brandt, professor of astronomy and astrophysics and professor of physics at Penn State, as well as principal investigator of the relevant Chandra Deep Field-South data.

The researchers identified the likely origin of XT2 by studying how its X-ray light varied with time, and comparing this behavior with predictions made in 2013 by coauthor Bing Zhang, professor and associate dean for research at the University of Nevada, Las Vegas.

The X-rays showed a characteristic signature that matched those astronomers predicted for a newly-formed magnetar—a neutron star spinning around hundreds of times per second and possessing a tremendously strong magnetic field about a quadrillion times that of Earth’s.

The team thinks that the magnetar lost energy in the form of an X-ray-emitting wind, slowing down its rate of spin as the source faded. The amount of X-ray emission stayed roughly constant in X-ray brightness for about 30 minutes, then decreased in brightness by more than a factor of 300 over 6.5 hours before becoming undetectable. This behavior indicates that the neutron star merger produced a new, larger neutron star that survived at least a few hours rather than collapsing immediately into a black hole.\

This result is important because it gives astronomers a chance to learn about the interior of neutron stars, objects that are so dense that their properties could never be replicated on Earth.

“We can’t throw neutron stars together in a lab to see what happens, so we have to wait until the universe does it for us,” says Zhang. “If two neutron stars can collide and a heavy neutron star survives, then this tells us that their structure is relatively stiff and resilient.”

Massive mergers

Neutron-star mergers have been prominent in the news since the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves from one in 2017. That source, known as GW170817, produced a burst of gamma rays and an afterglow in light many other telescopes, including Chandra, detected. The research team thinks that XT2 would also have been a source of gravitational waves, however it occurred before Advanced LIGO started its first observing run, and it was too distant to have been detected in any case.

The team also considered whether a different phenomenon, the collapse of a massive star, could have caused XT2 rather than a neutron star merger. However, XT2 is in the outskirts of its host galaxy, which aligns with the idea that supernova explosions that left behind the neutron stars kicked them out of the center a few billion years earlier.

The galaxy itself also has certain properties—including a low rate of star formation compared to other galaxies of a similar mass—that are much more consistent with the type of galaxy where the merger of two neutron stars is expected to occur. Massive stars, by contrast, are young and associated with high rates of star formation.

“The host-galaxy properties of XT2 indeed boost our confidence in explaining its origin,” says coauthor Ye Li, from Peking University.

The team estimated the rate at which events like XT2 should occur, and found that it agrees with the rate deduced from the detection of GW170817. However, both estimates are highly uncertain because they depend on the detection of just one object each, so more examples are needed.

“There must be more exciting transients that are still undiscovered in Chandra’s archival X-ray data,” says Guang Yang, graduate student in astronomy and astrophysics at Penn State and an author of the paper whose current research focuses on rate constraints for events like XT2. “These old data are really a gold mine.”

Additional researchers from Penn State, Nanjing University, Pontifica Universidad Católica de Chile, University of Arkansas, USTC, and the Chinese Academy of Sciences contributed to the research. Chandra’s Advanced CCD Imaging Spectrometer gathered the relevant data for this research. NASA’s Marshall Space Flight Center in Huntsville, Alabama manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts controls Chandra’s science and flight operations.

Source: Penn State

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What it means when lungs crackle and wheeze

Wed, 2019-04-17 18:15

Crackling and wheezing lungs could be the sounds of a disease progressing, according to new research.

A new study describes how the mechanics that produce those noises with every breath are likely a cause of injury and inflammation.

The findings, based on evidence from experiments on microfluidic chips and on animal models, could eventually change treatment of lung diseases, says James Grotberg, professor of biomedical engineering at the College of Engineering and professor of surgery at the Medical School at the University of Michigan. They also represent a paradigm shift for how doctors understand what they hear through a stethoscope.

Here, Grotberg answers explains his research, which appears in the Annals of the American Thoracic Society.

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Sticky patch reduces damage after heart attack

Wed, 2019-04-17 17:57

An adhesive patch can provide support for damaged heart tissue, report researchers.

The new patch may one day help  reduce the stretching of heart muscle that often occurs after a heart attack.

Researchers developed the patch, which they made from a water-based hydrogel material, using computer simulations of heart function in order to fine tune the material’s mechanical properties. A study with rats showed that the patch was effective in preventing left ventricle remodeling—a stretching of the heart muscle that’s common after a heart attack and can reduce the function of the heart’s main pumping chamber.

The research also showed that the computer-optimized patch outperformed patches whose mechanical properties had been selected on an ad hoc basis.

Support system

“Part of the reason that it’s hard for the heart to recover after a heart attack is that it has to keep pumping,” says Huajian Gao, a professor of engineering at Brown University and a coauthor of the paper. “The idea here is to provide mechanical support for damaged tissue, which hopefully gives it a chance to heal.”

Prior research had shown that mechanical patches could be effective, the researchers say, but no one had done any research on what the optimum mechanical properties of such a patch might be. As a result, the thickness and stiffness of potential patches varies widely. And getting those properties right is important, Gao says.

“If the material is too hard or stiff, then you could confine the movement of the heart so that it can’t expand to the volume it needs to,” he says. “But if the material is too soft, then it won’t provide enough support. So we needed some mechanical principles to guide us.”

To develop those principles, the researchers developed a computer model of a beating heart, which captured the mechanical dynamics of both the heart itself and the patch when fixed to the heart’s exterior. Yue Liu, a graduate student who led the modeling work, says the model had two key components.

“One part was to model normal heart function—the expanding and contracting,” Liu says. “Then we applied our patch on the outside to see how it influenced that function, to make sure that the patch doesn’t confine the heart. The second part was to model how the heart remodels after myocardial infarction, so then we could look at how much mechanical support was needed to prevent that process.”

Fluid and solid qualities

With those properties in hand, the team turned to the biomaterials lab of Lei Yang, a PhD graduate who is now a professor at Soochow University and Hebei University of Technology in China. Yang and his team developed a hydrogel material made from food-sourced starch that could match the properties from the model.

The key to the material is that it’s viscoelastic, meaning it combines fluid and solid properties. It has fluid properties up to a certain amount of stress, at which point it solidifies and becomes stiffer. That makes the material ideal for both accommodating the movement of the heart and for provided necessary support, the researchers say.

The material is also cheap (a patch costs less than a penny, the researchers say) and easy to make, and experiments showed that it was nontoxic. The rodent study ultimately showed that it was effective in reducing post-heart attack damage.

“The patch provided nearly optimal mechanical supports after myocardial infarction (i.e. massive death of cardiomyocytes),” says coauthor Ning Sun, a cardiology researcher at Fudan University in China. “[It] maintained a better cardiac output and thus greatly reduced the overload of those remaining cardiomyocytes and adverse cardiac remodeling.”

Biochemical markers showed that the patch reduced cell death, scar tissue accumulation, and oxidative stress in tissue damaged by heart attack.

More testing is required, the researchers say, but the initial results are promising for eventual use in human clinical trials.

“It remains to be seen if it will work in humans, but it’s very promising,” Gao says. “We don’t see any reason right now that it wouldn’t work.”

The research appears in Nature Biomedical Engineering.

The National Natural Science Foundation of China and the US National Science Foundation supported the research.

Source: Brown University

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Scientists use ‘x-ray vision’ to see how catfish nab prey

Wed, 2019-04-17 12:53

Scientists used a powerful X-ray imaging system to discover how catfish move joints throughout their head in a concerted manner to suck in their prey.

The imaging system, which tracked catfish as they caught and swallowed prey, helped scientists develop a precise understanding of the complex set of motions required to create the suction necessary to eat. They found that many of the bones in the catfish skull work in a coordinated manner to catch food—but move more independently when it’s time to swallow.

“Fish have the most mobile skulls of vertebrates,” says Aaron Olsen, a postdoctoral research associate in Brown University’s ecology and evolutionary biology department. “Fish have over a dozen moving pieces in their skull, and they’re all connected together by joints and ligaments in these closed loops called ‘linkages’ in engineering.

A video of a catfish catching and swallowing an earthworm that shows the coordinated head movements necessary to feed. (Credit: Brainerd Lab/Brown)

“In comparison, humans have moving lower jaws and middle ear bones, but that’s it. The heads of fishes also have very diverse shapes, so we can study how these complex systems evolved in lots of different linages of fishes.”

Bones and muscles

To make the observations, researchers used a 3D-imaging technology called X-ray Reconstruction of Moving Morphology (XROMM). The technology combines CT scans of a skeleton with high-speed X-ray video, aided by tiny implanted metal markers, to create visualizations of how bones and muscles move inside humans and animals.

The technique is so precise that scientists can track movements with errors equivalent to only the width of a human hair.

“XROMM basically gives us X-ray vision to watch how multiple bones move within an animal as they perform a behavior,” Olsen says.

A model of a catfish skull with each bone highlighted in a different color. Catfish have over a dozen moving pieces in their skull. (Credit: Aaron Olsen/Brown)

In this study, the team used XROMM to watch three catfish catch and swallow prey—including food pellets, bits of squid, and earthworms. First, the fish move their whisker-like barbels back and forth in the tank.

Immediately after a barbel touches a piece of food, four primary bones that surround the mouth and throat expand outward in a consistent and coordinated manner to form the suction necessary to catch it.

On the other hand, these bones move more independently and less consistently as the fish swallow. Olsen isn’t certain why swallowing is less coordinated.

The result of the XROMM video of catfish capturing and then swallowing prey, showing the strong coordination the four primary skull bones during prey capture and the more independent movements of the bones during swallowing. (Credit: Brainerd Lab/Brown)

“It seems like different tasks need different levels of coordination,” Olsen said. “But what determines a good level of coordination for a specific task is an open question. What our study shows is that these natural behaviors have different levels of coordination. We’re not sure if they strictly require different levels of coordination.”

Different shapes, same tasks

Previous research from the lab of professor and senior researcher Elizabeth Brainerd used XROMM to study the feeding behavior of other fish, including bass and sharks. Largemouth bass protrude their jaws, which helps catch prey, but catfish can’t protrude their jaws that way, Olsen says. Instead, the bone critical for that action in bass evolved into the base of the whisker-like barbels in catfish.

Bamboo sharks are distantly related to all bony fish, including catfish. However, both bamboo sharks and catfish have powerful shoulders, or pectoral girdles, that both species move extensively during feeding, Olsen says.

Comparing different species of fish with different body shapes, skull structures, and feeding behaviors can clarify how fish with different body shapes evolved different structures and mechanisms to solve similar tasks, Olsen says.

Olsen is in the process of constructing a model to explain how the bones and ligaments that comprise the catfish skull move together as a complex system.

The paper appears in the Proceedings of the Royal Society B. Additional coauthors are from Brown and George Washington University. The National Science Foundation and the Bushnell Research and Education Fund supported the research.

Source: Brown University

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