Key brain region was 'recycled' as humans developed the ability to read

Part of the visual cortex dedicated to recognizing objects appears predisposed to identifying words and letters, a study finds

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

 

CAMBRIDGE, MA -- Humans began to develop systems of reading and writing only within the past few thousand years. Our reading abilities set us apart from other animal species, but a few thousand years is much too short a timeframe for our brains to have evolved new areas specifically devoted to reading.

To account for the development of this skill, some scientists have hypothesized that parts of the brain that originally evolved for other purposes have been "recycled" for reading. As one example, they suggest that a part of the visual system that is specialized to perform object recognition has been repurposed for a key component of reading called orthographic processing -- the ability to recognize written letters and words.

A new study from MIT neuroscientists offers evidence for this hypothesis. The findings suggest that even in nonhuman primates, who do not know how to read, a part of the brain called the inferotemporal (IT) cortex is capable of performing tasks such as distinguishing words from nonsense words, or picking out specific letters from a word.

"This work has opened up a potential linkage between our rapidly developing understanding of the neural mechanisms of visual processing and an important primate behavior -- human reading," says James DiCarlo, the head of MIT's Department of Brain and Cognitive Sciences, an investigator in the McGovern Institute for Brain Research and the Center for Brains, Minds, and Machines, and the senior author of the study.

Rishi Rajalingham, an MIT postdoc,, is the lead author of the study, which appears today in Nature Communications. Other MIT authors are postdoc Kohitij Kar and technical associate Sachi Sanghavi. The research team also includes Stanislas Dehaene, a professor of experimental cognitive psychology at the Collège de France.

Word recognition

Reading is a complex process that requires recognizing words, assigning meaning to those words, and associating words with their corresponding sound. These functions are believed to be spread out over different parts of the human brain.

Functional magnetic resonance imaging (fMRI) studies have identified a region called the visual word form area (VWFA) that lights up when the brain processes a written word. This region is involved in the orthographic stage: It discriminates words from jumbled strings of letters or words from unknown alphabets. The VWFA is located in the IT cortex, a part of the visual cortex that is also responsible for identifying objects.

DiCarlo and Dehaene became interested in studying the neural mechanisms behind word recognition after cognitive psychologists in France reported that baboons could learn to discriminate words from nonwords, in a study that appeared in Science in 2012.

Using fMRI, Dehaene's lab has previously found that parts of the IT cortex that respond to objects and faces become highly specialized for recognizing written words once people learn to read.

"However, given the limitations of human imaging methods, it has been challenging to characterize these representations at the resolution of individual neurons, and to quantitatively test if and how these representations might be reused to support orthographic processing," Dehaene says. "These findings inspired us to ask if nonhuman primates could provide a unique opportunity to investigate the neuronal mechanisms underlying orthographic processing."

The researchers hypothesized that if parts of the primate brain are predisposed to process text, they might be able to find patterns reflecting that in the neural activity of nonhuman primates as they simply look at words.

To test that idea, the researchers recorded neural activity from about 500 neural sites across the IT cortex of macaques as they looked at about 2,000 strings of letters, some of which were English words and some of which were nonsensical strings of letters.

"The efficiency of this methodology is that you don't need to train animals to do anything," Rajalingham says. "What you do is just record these patterns of neural activity as you flash an image in front of the animal."

The researchers then fed that neural data into a simple computer model called a linear classifier. This model learns to combine the inputs from each of the 500 neural sites to predict whether the string of letters that provoked that activity pattern was a word or not. While the animal itself is not performing this task, the model acts as a "stand-in" that uses the neural data to generate a behavior, Rajalingham says.

Using that neural data, the model was able to generate accurate predictions for many orthographic tasks, including distinguishing words from nonwords and determining if a particular letter is present in a string of words. The model was about 70 percent accurate at distinguishing words from nonwords, which is very similar to the rate reported in the 2012 Science study with baboons. Furthermore, the patterns of errors made by model were similar to those made by the animals.

Neuronal recycling

The researchers also recorded neural activity from a different brain area that also feeds into IT cortex: V4, which is part of the visual cortex. When they fed V4 activity patterns into the linear classifier model, the model poorly predicted (compared to IT) the human or baboon performance on the orthographic processing tasks.

The findings suggest that the IT cortex is particularly well-suited to be repurposed for skills that are needed for reading, and they support the hypothesis that some of the mechanisms of reading are built upon highly evolved mechanisms for object recognition, the researchers say.

The researchers now plan to train animals to perform orthographic tasks and measure how their neural activity changes as they learn the tasks.

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The research was funded by the Simons Foundation and the U.S. Office of Naval Research.

What influences adolescents to share marijuana-related content on social media?

EDWARD R. MURROW COLLEGE OF COMMUNICATION

 

PULLMAN, Wash. - With social media use being as prevalent as ever, a new study from Washington State University's Edward R. Murrow College of Communication shows that adolescents may share marijuana-related content on social media in an effort to fit in with their peers.

Led by Murrow College Associate Professor Jessica Willoughby, this recently published study, "An Exploratory Study of Adolescents' Social Media Sharing of Marijuana-Related Content", examined the types of marijuana-related content that adolescents are posting on social media and what factors may influence adolescents' decisions to share marijuana-related content on social media.

The team of researchers surveyed 350 participants between the ages of 13-17 living in Washington state, where recreational marijuana use is legal for people 21 and older. The participants answered various questions related to their social media habits and whether they posted content relating to marijuana.

Previous research shows that young people may be exposed to a variety of marijuana-related content on social media, and this exposure may impact marijuana use. Other studies demonstrated youth and young adults' active engagement in displaying risky behaviors on social media, including marijuana use, which highlights a shared concern with the normalization of risky behaviors among young people.

"Nearly one-third of Washington adolescents we surveyed indicated that they shared marijuana-related content - primarily memes, pictures, and videos - on social media platforms such as Facebook, Snapchat, and Instagram," Willoughby said. "Even though many marijuana-related web sites require viewers to verify they are old enough to legally use the product, such verification processes are absent from social media."

"The adolescents we surveyed were also more likely to share marijuana-related social media content if they perceived their peers use marijuana and if they believed their parents would approve of them sharing such content," said Murrow College Associate Dean Stacey J.T. Hust, who is second author of the study. "In contrast, if they perceived that their parents were monitoring their behavior, in general, they were less likely to share marijuana-related content on social media.

"Essentially, adolescents who reported their parents were aware of where they were going and who they were spending time with, were less likely to share marijuana-related content," Willoughby said. "But, we didn't find an association between parents checking their adolescents' social media and the sharing of marijuana-related content."

The motives behind sharing marijuana-related content are still unclear, according to this study. As young people use social media for a variety of reasons, including to present themselves to others, it is important to gauge the risk-related messages youth display on social media and what may be associated with this sharing on social platforms.

"Overall, our findings suggest adolescents may post content that is inconsistent with their personal beliefs in a desire to conform to their peers," Hust said. This is of potential concern because young people tend to overestimate peer use and acceptance of substance use, and social media posting related to substance use may imply an intention to use substances or increase perceptions of their use.

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Scientists propose a novel method for controlling fusion reactions

DOE/PRINCETON PLASMA PHYSICS LABORATORY

 

IMAGE: PHYSICIST SUYING JIN. view more 

CREDIT: PHOTO COURTESY OF SUYING JINL

Scientists have found a novel way to prevent pesky magnetic bubbles in plasma from interfering with fusion reactions - delivering a potential way to improve the performance of fusion energy devices. And it comes from managing radio frequency (RF) waves to stabilize the magnetic bubbles, which can expand and create disruptions that can limit the performance of ITER, the international facility under construction in France to demonstrate the feasibility of fusion power.

Magnetic islands

Researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have developed the new model for controlling these magnetic bubbles, or islands. The novel method modifies the standard technique of steadily depositing radio (RF) rays into the plasma to stabilize the islands -- a technique that proves inefficient when the width of an island is small compared with the characteristic size of the region over which the RF ray deposits its power.

This region denotes the "damping length," the area over which the RF power would typically be deposited in the absence of any nonlinear feedback. The effectiveness of the RF power can be greatly reduced when the size of the region is greater than the width of the island -- a condition called "low-damping" -- as much of the power then leaks from the island.

Tokamaks, doughnut-shaped fusion facilities that can experience such problems, are the most widely used devices by scientists around the world who seek to produce and control fusion reactions to provide a virtually inexhaustible supply of safe and clean power to generate electricity. Such reactions combine light elements in the form of plasma -- the state of matter composed of free electrons and atomic nuclei that makes up 99 percent of the visible universe -- to generate the massive amounts of energy that drives the sun and stars.

Overcoming the problem

The new model predicts that depositing the rays in pulses rather than steady state streams can overcome the leakage problem, said Suying Jin, a graduate student in the Princeton Program in Plasma Physics based at PPPL and lead author of a paper (link is external) that describes the method in Physics of Plasmas. "Pulsing also can achieve increased stabilization in high-damping cases for the same average power," she said.

For this process to work, "the pulsing must be done at a rate that is neither too fast nor too slow," she said. "This sweet spot should be consistent with the rate that heat dissipates from the island through diffusion."

The new model draws upon past work by Jin's co-authors and advisors Allan Reiman, a Distinguished Research Fellow at PPPL, and Professor Nat Fisch, director of the Program in Plasma Physics at Princeton University and associate director for academic affairs at PPPL. Their research provides the nonlinear framework for the study of RF power deposition to stabilize magnetic islands.

"The significance of Suying's work," Reiman said, "is that it expands considerably the tools that can be brought to bear on what is now recognized as perhaps the key problem confronting economical fusion using the tokamak approach. Tokamaks are plagued by these naturally arising and unstable islands, which lead to disastrous and sudden loss of the plasma."

Added Fisch: "Suying's work not only suggests new control methodologies; her identification of these newly predicted effects may force us to re-evaluate past experimental findings in which these effects might have played an unappreciated role. Her work now motivates specific experiments that could clarify the mechanisms at play and point to exactly how best to control these disastrous instabilities."

Original model

The original model of RF deposition showed that it raises the temperature and drives current in the center of an island to keep it from growing. Nonlinear feedback then kicks in between the power deposition and changes in the temperature of the island that allows for greatly improved stabilization. Governing these temperature changes is the diffusion of heat from the plasma at the edge of the island.

However, in high-damping regimes, where the damping length is smaller than the size of the island, this same nonlinear effect can create a problem called "shadowing" during steady state deposition that causes the RF ray to run out of power before it reaches the center of the island.

"We first looked into pulsed RF schemes to solve the shadowing problem," Jin said. "However, it turned out that in high-damping regimes nonlinear feedback actually causes pulsing to exacerbate shadowing, and the ray runs out of power even sooner. So we flipped the problem around and found that the nonlinear effect can then cause pulsing to reduce the power leaking out of the island in low-damping scenarios."

These predicted trends lend themselves naturally to experimental verification, Jin said. "Such experiments," she noted, "would aim to show that pulsing increases the temperature of an island until optimum plasma stabilization is reached."

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Funding for this research comes from the DOE Office of Science.

PPPL, on Princeton University's Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas -- ultra-hot, charged gases -- and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy's Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit energy.gov/science (link is external).

FSU geologists publish new findings on carbonate melts in Earth's mantle

FLORIDA STATE UNIVERSITY

 

Geologists from Florida State University's Department of Earth, Ocean and Atmospheric Science have discovered how carbon-rich molten rock in the Earth's upper mantle might affect the movement of seismic waves.

The new research was coauthored by EOAS Associate Professor of Geology Mainak Mookherjee and postdoctoral researcher Suraj Bajgain. Findings from the study were published in the journal Proceedings of the National Academy of Sciences .

"This research is quite important since carbon is a crucial constituent for the habitability of the planet, and we are making strides to understand how solid earth may have played a role in storing and influencing the availability of carbon in the Earth's surface," Mookherjee said. "Our research gives us a better understanding of the elasticity, density and compressibility of these rocks and their role in Earth's carbon cycle."

Carbon, one of the primary building blocks for life, is widely distributed throughout the Earth's upper mantle and is mostly stored in forms of carbonate minerals as accessory minerals in mantle rocks. When carbonate-rich magma erupts on the surface, it is notable for its unique, mud-like appearance. These types of eruptions occur at specific locations around the world, such as at the Ol Doinyo Lengai volcano in Tanzania.

Experts believe that the presence of carbonates in rocks significantly lowers the temperature at which they melt. Carbonates that sink to the Earth's interior, via a process known as subduction, likely cause this low-degree melting of the Earth's upper mantle rocks, which plays an important role in the planet's deep carbon cycle.

"Earth's mantle has less free oxygen available at increasing depths," Mookherjee said. "As the mantle upwells through a process of mantle convection, the slowly moving rocks that were reduced, or had less oxygen, at a greater depth become progressively more oxidized at shallower depth. The carbon in the mantle is likely to be reduced deeper in the Earth and get oxidized as the mantle upwells."

This change in depth-dependent oxidation state is likely to cause melting of mantle rocks, a process called redox melting, which could produce carbon-rich molten rock, also known as melts. These melts are likely to affect the physical property of a rock, which can be detected using geophysical probes such as seismic waves, he said.

Prior to this study, geologists had poor knowledge of the elastic properties of these carbonate-induced partial melts, which made them difficult to directly detect.

One set of clues that geologists use to better understand their science are measurements of seismic waves as they move through the layers of the Earth. A type of seismic wave known as a compressional wave is faster than another type known as a shear wave, but at depths of around 180 to 330 kilometers into the Earth, the ratio of their speeds is even higher than is typical.

"This elevated ratio of compressional waves to the shear waves has been a puzzle, and using the findings from our study, we are able to explain this perplexing observation," Mookherjee said.

Minor quantities of carbon-rich melts, approximately 0.05 percent, might be dispersed pervasively through the Earth's deep upper mantle, and that may lead to the elevated ratio of compressional to shear sound velocity, researchers explained.

To conduct the study, researchers took high-pressure ultrasonic measurements and density measurements on cores of the carbonate mineral dolomite. These experiments were complemented by theoretical simulations to provide a new understanding of the fundamental physical properties of carbonate melts.

"We have been trying to understand the elastic and transport properties of aqueous fluids, silicate melt and metallic melt properties, to gain better insight into the mass of volatiles stored in the deep solid earth," Bajgain said.

These findings mean the partially molten rocks in the mantle could hold as much as 80 to 140 parts per million of carbon, which would be 20 to 36 million gigatons of carbon in the deep upper mantle region, making it a substantial carbon reservoir. In comparison, Earth's atmosphere contains just over 410 ppm of carbon, or around 870 gigatons.

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Researchers from Case Western Reserve University in Cleveland, Southern University of Science and Technology in Shenzhen, China, and the University of Chicago contributed to this study. They performed calculations at the High Performance Computing Cluster at Florida State and at supercomputing facilities provided by the National Science Foundation's Extreme Science and Engineering Discovery Environment.

The work was partly supported by the National Science Foundation and the National Natural Science Foundation of China.

Epidemic model shows how COVID-19 could spread through firefighting camps

Demonstrates potential risks, scenarios COVID-19 could pose for fire management

COLORADO STATE UNIVERSITY

 

IMAGE: LARIMER COUNTY AND WELLINGTON FIREFIGHTERS MOP UP A SPOT FIRE AREA ON THE ELK FIRE, OCT. 18, 2019. view more 

CREDIT: BILL COTTON/COLORADO STATE UNIVERSITY PHOTOGRAPHY

With wildfire season in full swing, a COVID-19 outbreak at a traditional large fire camp is a potential disaster. A transient, high-density workforce of firefighters and volunteers responds to blazes while staying in close quarters with limited hygiene - conditions that could facilitate the spread of a contagious respiratory disease.

To support fire agencies as they continue their mission-critical work, a team that includes Colorado State University experts has developed an epidemiological modeling exercise for the USDA Forest Service and other fire managers that demonstrates potential risks and various scenarios COVID-19 could pose for the fire management community. Their model is published in the journal Fire.

The report is co-authored by Jude Bayham, assistant professor in the CSU Department of Agricultural and Resource Economics; and Erin Belval, research scientist in the CSU Department of Forest and Rangeland Stewardship; with first author Matthew P. Thompson, Research Forester at the USDA Forest Service Rocky Mountain Research Station. Bayham and Belval worked with Thompson on the study under a longstanding joint venture agreement with the Forest Service on wildfire-related research, which primarily operates through a partnership with the Warner College of Natural Resources. Thompson serves as the team's liaison to the fire management community.

The researchers developed a simulation model of COVID-19 in the context of a wildfire incident in which the population of firefighters changes over time. The team then analyzed a range of scenarios with different infection transmission rates, percentages of arriving workers who are infected, and fatality rates.

They applied their model to real firefighter population data from three recent wildfires - Highline, Lolo Peak and Tank Hollow - to illustrate potential outbreak dynamics.

During the Highline fire in Idaho, for example, which at its peak had over 1,000 firefighters on site (See Figure 1.), a worst-case scenario would have seen close to 500 infections, and a best-case scenario of eight infections. (See Figure 7.) The researchers used a variety of infection fatality rates to estimate possible deaths due to COVID-19 on the fires, ranging from a low of 0.1% to an "extreme" of 2%, with a medium, or best-guess, of 0.3%. (See Table 1.)

Model is not a prediction

Like most modeling exercises, the report is not intended to predict real numbers; rather, it is a tool for comparing different scenarios and analyzing how various interventions could have small or large effects.

"There is a need in the modeling community to better communicate what we can and cannot learn from models," Bayham said. "The model itself is not meant to be predictive in the sense of number of cases or deaths, because there are so many things moving."

Bayham said the model does provide insight into the relative benefits of two risk-mitigation strategies: screening; and implementing social distancing measures at camps.

They found that aggressive screening as soon as firefighters arrive at camp could reduce the spread of infection, but those benefits diminish as a wildfire incident goes on longer. For longer campaigns lasting several months, aggressive social distancing measures, including increased use of remote briefings, dispersed sleeping camps, and operating under the "module as one" concept, would be more effective at reducing infections than screening. "Module as one" is a social distancing adaptation in which a crew operates mostly as normal but isolates from other, similarly isolating crews.

"It all comes down to exposure, which is a basic risk management concept," Thompson said. "Reducing the exposure of susceptible individuals to those who may be infectious is the idea behind screening and social distancing. Our results underscore the importance of deploying these risk mitigation measures and provide insights into how characteristics of a wildfire incident factor into the effectiveness of these mitigations."

Bayham added, "Both interventions are useful, and they both have an effect, but they each have times and places where they are even more effective,"

Such findings could help inform the wildland fire management community as it develops guidance for fire response strategies during the pandemic.

Thompson added, "I'm fortunate to have worked with Jude and Erin for several years now, and in my opinion their collective depth and breadth of expertise is uniquely well suited to address this complex issue. We're grateful for the support from the Joint Fire Science Program and more broadly the fire management community to continue this important work."

Extending the work

The team will continue their work with a $74,200 award from the Joint Fire Science Program by way of the USDA Forest Service Rocky Mountain Research Station joint venture agreement. They plan to extend their model and create an interactive dashboard for agencies to provide real-time modeling and risk assessment support as fire season continues.

They are also working on a model that would be better suited to analyze season-long implications of COVID-19 outbreaks, spread across multiple fires and geographic distances.

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THIS HAS BEEN THE DREAM SINCE FIRST DISCOVERED IN THE SEVENTIES 

How thoughts could one day control electronic prostheses, wirelessly

Today's brain implants already connect the nervous system to electronic devices to help people with spinal cord injuries regain some motor control. But they use ungainly wires.

STANFORD SCHOOL OF ENGINEERING

 

IMAGE: PHOTO OF A CURRENT NEURAL IMPLANT, THAT USES WIRES TO TRANSMIT INFORMATION AND RECEIVE POWER. NEW RESEARCH SUGGESTS HOW TO ONE DAY CUT THE WIRES. view more 

CREDIT: SERGEY STAVISKY

Stanford researchers have been working for years to advance a technology that could one day help people with paralysis regain use of their limbs, and enable amputees to use their thoughts to control prostheses and interact with computers.

The team has been focusing on improving a brain-computer interface, a device implanted beneath the skull on the surface of a patient's brain. This implant connects the human nervous system to an electronic device that might, for instance, help restore some motor control to a person with a spinal cord injury, or someone with a neurological condition like amyotrophic lateral sclerosis, also called Lou Gehrig's disease.

The current generation of these devices record enormous amounts of neural activity, then transmit these brain signals through wires to a computer. But when researchers have tried to create wireless brain-computer interfaces to do this, it took so much power to transmit the data that the devices would generate too much heat to be safe for the patient.

Now, a team led by electrical engineers and neuroscientists Krishna Shenoy, PhD, and Boris Murmann, PhD, and neurosurgeon and neuroscientist Jaimie Henderson, MD, have shown how it would be possible to create a wireless device, capable of gathering and transmitting accurate neural signals, but using a tenth of the power required by current wire-enabled systems. These wireless devices would look more natural than the wired models and give patients freer range of motion.

Graduate student Nir Even-Chen and postdoctoral fellow Dante Muratore, PhD, describe the team's approach in a Nature Biomedical Engineering paper.

The team's neuroscientists identified the specific neural signals needed to control a prosthetic device, such as a robotic arm or a computer cursor. The team's electrical engineers then designed the circuitry that would enable a future, wireless brain-computer interface to process and transmit these these carefully identified and isolated signals, using less power and thus making it safe to implant the device on the surface of the brain.

To test their idea, the researchers collected neuronal data from three nonhuman primates and one human participant in a (BrainGate) clinical trial.

As the subjects performed movement tasks, such as positioning a cursor on a computer screen, the researchers took measurements. The findings validated their hypothesis that a wireless interface could accurately control an individual's motion by recording a subset of action-specific brain signals, rather than acting like the wired device and collecting brain signals in bulk.

The next step will be to build an implant based on this new approach and proceed through a series of tests toward the ultimate goal.

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Ancient mountains recorded in Antarctic sandstones reveal potential links to global events

UNIVERSITY OF WISCONSIN OSHKOSH

 

IMAGE: A TEAM OF RESEARCHERS LED BY UW OSHKOSH GEOLOGIST TIMOTHY PAULSEN ANALYZED SANDSTONE SAMPLES COLLECTED FROM THE TRANSANTARCTIC MOUNTAINS. view more 

CREDIT: PHOTO COURTESY OF TIMOTHY PAULSEN, UNIVERSITY OF WISCONSIN OSHKOSH

A new analysis of sandstones from Antarctica indicates there may be important links between the generation of mountain belts and major transitions in Earth's atmosphere and oceans.

A team of researchers analyzed the chemistry of tiny zircon grains commonly found in the Earth's continental rock record to determine their ages and chemical compositions. The team included scientists from the University of Wisconsin Oshkosh, Michigan Technological University and ETH Zurich in Switzerland.

The study was published recently in the international peer-reviewed journal Terra Nova, which features short innovative papers about the solid Earth and planetary sciences.

"Mountain building occurs in association with the plate tectonic motions of the continents," said Paulsen, the lead author on the paper. "Geologists have long recognized that the generation of significant mountainous relief has the potential to profoundly influence the chemistry of the Earth's oceans and atmosphere."

Yet there are significant questions about the patterns of mountain building in Earth's past, especially associated with the ancient rock record leading up to the explosion of life about 541 million years ago.

"Mountains tend to be worn down by water and wind that ultimately transports their sedimentary remains to the oceans, leaving an incomplete puzzle for geologists to fit together," said Deering, a coauthor on the paper. "However, there is increasing evidence that missing pieces of the puzzle are found in the sands of ancient beaches and rivers, which are essentially the remnants of mountains produced by weathering and erosion."

The researchers' findings, based on an analysis of a large sample of zircon grains from sandstone recovered in Antarctica, may signify key links in the evolution of the Earth's rock cycle and its atmosphere and oceans.

"We found two primary periods of increased average crustal thickness associated with volcanic chains along convergent plate boundaries, implying an increased proportion of higher mountains at these times," Paulsen said.

"Both episodes occurred during major reorganization of the continents when they separated and drifted on the Earth's surface over time. They also overlap with snowball Earth glaciations--when the whole Earth was frozen over--and associated steps in oxygenation of the atmosphere, which may have been critical for the evolution of life. These correlations suggest an important causal link between plate tectonics and major transitions in Earth's atmosphere and oceans."

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Changes in land evaporation shape the climate

INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

 

IMAGE: TO PRODUCE BETTER CLIMATIC PREDICTIONS, SCIENTISTS ESTIMATE HOW MUCH WATER IS EVAPORATED FROM THE VEGETATED LAND SURFACE view more 

CREDIT: ÁKOS SZABÓ

Accurate estimation of how much water is evaporated from the vegetated land surface is a challenging task. A physical-based method--such as the complementary relationship (CR) of evaporation, which explicitly accounts for the dynamic feedback mechanisms in the soil-land-atmosphere system and requires minimal data--is advantageous for tracking the ongoing changes in the global hydrological cycle and relating them to historical base values.

Unfortunately, such a method cannot be employed with recently developed remote sensing-based approaches, as they are typically available only for the last couple of decades or so.

An international team of Hungarian, American and Chinese scientists have demonstrated that an existing calibration-free version of the CR method that inherently tracks the aridity changes of the environment in each step of the calculations can better detect long-term trends in continental-scale land evaporation rates than a recently developed and globally calibrated one without such dynamic adjustments to aridity.

With the ongoing climate change, the global hydrological cycle is affected significantly. As climate research indicates, wet areas will get even wetter in general, while dry ones drier, which is not the best scenario for the vast semi-arid and arid regions of the globe. In order to produce better climatic predictions, general circulation models need to upgrade their existing evaporation estimation algorithms. A computational method that automatically adjusts its predictions to short- as well as long-term changes in aridity can improve the existing algorithms employed by these climate models.

"By repeatedly demonstrating the superb capabilities of our calibration-free evaporation method in all venues accessible to us, our ultimate goal is to have the climate modeling community take notice and give it a try," explains Dr Jozsef Szilagyi, the lead author of the study. "As it requires only a few, surface-measured meteorological input variables, such as air temperature, humidity, wind speed and net surface radiation, without detailed information of the soil moisture status or land-surface properties, it can be readily applied with available historical records of meteorological data and see if it indeed improves past predictions of the climate or not."

"Any changes in land use and land cover is inherently accounted for by the CR method via its dynamic aridity term that does not even require precipitation measurements--one of the most variable and difficult meteorological parameter to predict," he concludes.

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The study is published in Advances in Atmospheric Sciences.

This research was supported by the Budapest University of Technology Water Sciences and a Disaster Prevention FIKP grant of EMMI, Hungary.

Maldives records highest level of micro plastic pollution on the planet

Micro plastic pollution in the Maldives, a global tourist destination, is amongst the highest in the world

FLINDERS UNIVERSITY

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VIDEO: FLINDERS UNIVERSITY MALDIVES RESEARCH VIDEO- DR EMILY FOBERT ON LOCATION. view more 

CREDIT: FLINDERS UNIVERSITY https://www.eurekalert.org/multimedia/pub/239420.php

The amount of micro plastic pollution in waters around the Maldives, a global tourist destination known for its beautiful coastline, is amongst the highest in the world and has the potential to severely impact marine life in shallow reefs and threaten the livelihoods of island communities.

Microplastics are pieces of plastic waste that measure less than 5 millimetres long, and due to their often microscopic size are considered invisible water pollutants. Small pieces of plastic can break down over time from plastic bottles, textiles and clothing, remain in the world's oceans.

Marine scientists from Flinders University in Australia recorded the levels of plastic pollution in sand across 22 sites off the coast of Naifaru, the most populous island in Lhaviyani Atoll, to determine how much microplastic is present around the island. Microplastic distribution was found to be ubiquitous in the marine environment, with the results published in Science of the Total Environment journal.

Flinders University Honours student and lead researcher Toby Patti says micro plastics are highly concentrated in waters around Naifaru.

"The concentration of microplastics found on Naifaru in the Maldives (55 -1127.5 microplastics/kg) was greater than those previously found on a highly populated site at Tamil Nadu, India (3 - 611 microplastics/kg), and was a similar concentration to that found on inhabited and uninhabited islands elsewhere in the Maldives (197 -822 particles/kg)."

Microplastic concentration map around Naifaru, an island in the Maldives 141 km north of the capital, Malé. It is the capital and most populous island of Lhaviyani Atoll.

"The majority of micro plastics found in our study were less than 0.4mm in width, so our results raise concerns about the potential for microplastic ingestion by marine organisms in the shallow coral reef system. The accumulation of microplastics is a serious concern for the ecosystem and the local community living off of these marine resources, and can have a negative impact on human health."

The high levels of microplastics could have been transported by ocean currents from neighbouring countries in the Indian Ocean like India, as well as from Maldivian land reclamation policies, poor sewerage & wastewater systems.

Professor Karen Burke Da Silva says notorious 'rubbish islands' used as landfill sites are also contributing to the high concentration of microplastic found around the island.

"Current waste management practices in the Maldives cannot keep up with population growth and the pace of development. The small island nation encounters several challenges regarding waste management systems and has seen a 58% increase of waste generated per capita on local islands in the last decade," says Professor Burke Da Silva.

"Without a significant increase in waste reduction and rapid improvements in waste management, small island communities will continue to generate high levels of microplastic pollution in marine environments, with potential to negatively impact the health of the ecosystem, marine organisms, and local island communities."

The researchers are now looking at the stomach content of coral reef fish to see if they have bellies full of microplastics in a follow up study.

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