Mandatory state policies work best to curb power plant emissions, study finds

“Due to the current void in national leadership on the issue of climate change, efforts at the state and local level are more important than ever,” says Eri Saikawa, an assistant professor of Environmental Sciences. Saikawa is part of an Emory delegation to the U.N. Climate Change Conference talks in Bonn, Germany, which includes two faculty and 12 students.

By Carol Clark

U.S. state policies aimed at mitigating power plant emissions vary widely in effectiveness, finds a new study by researchers at Emory University.

Nature Climate Change published the analysis, which shows that policies with mandatory compliance are associated with the largest reductions in power plant emissions.

“Based on the results of our study, we recommend that states adopt a policy of mandatory greenhouse gas emissions registry and reporting for power plants,” says Eri Saikawa, an assistant professor in Emory’s Department of Environmental Sciences. “We also found a significant impact in states that adopt public benefit funds aimed at energy efficiency and renewable energy programs. These two policies not only are effective in reducing power-plant emission levels but also emissions intensity.” 

Saikawa, an expert in public policy and the science of emissions linked to global warming, co-authored the study with Emory graduate Geoff Martin, whose thesis project focused on the topic. Martin received his master’s degree in environmental sciences in May and now works as an energy coordinator for the town of Hartford, Vermont.

Their findings were released today as the U.N. Climate Change Conference (COP23) opens in Bonn, Germany. Delegates from around the world are gathering to hammer out details for meeting the goals of the 2015 Paris Agreement.

The United States was among the 195 countries that committed to this framework to reduce greenhouse gas emissions — although the Trump administration has said it plans to withdraw from this historic accord.

“Due to the current void in national leadership on the issue of climate change, efforts at the state and local level are more important than ever,” Saikawa says. “U.S. cities and states need to step up and do what they can.”

Emory is one of 50 universities from around the country to hold official U.N. observer status for COP23. Saikawa and Sheila Tefft, senior lecturer from the Department of English, will be on the ground in Bonn — leading a delegation of 11 Emory undergraduates and one graduate student as part of their co-taught class, “Climate Change and Society.”

The students will report news live from the event on Twitter under the hashtag #EmoryCOP23. They will also post longer reports, podcasts and videos on a web site they created for the event, Climate Talks Emory University.

Global atmospheric CO2 levels increased at record speed last year, to reach a level not seen for more than three million years, the U.N. warned in a report released last week. The U.S. government’s National Climate Assessment, also released last week, affirmed that climate change is driven almost entirely by human action and detailed how the country is already experiencing more extreme heat and rainfall events, more large wildfires and more flooding due to the warming climate.

About 30 percent of U.S. greenhouse gas emissions come from the electric power sector. For the Nature Climate Change paper, the researchers started out to review the potential impact of President Obama’s Clean Power Plan — which established the first national carbon pollution standards for power plants. When President Trump took office, and announced plans to repeal the Clean Power Plan, the researchers shifted focus.

They analyzed 17 policies adopted by various states relating to climate and energy. States that adopted a mandatory policy for power plants to register and report greenhouse gas emissions, along with three to four other policies, showed the largest reductions, at an average of 2.6 million metric tons of carbon dioxide (CO2) emissions per year.

The second most significant policy involved public benefit funds allotted for energy efficiency and renewable energy programs. That policy was associated with a reduction of about 1.5 million tons of CO2 emissions from power plants, when adopted with three to four other policies.

It’s unclear whether one of these single policies was the actual driver of the reduction in emissions, or an indicator that a state takes climate change mitigation seriously and is attacking the issue on many fronts, Saikawa says.

For instance, three states — New York, Connecticut and Oregon — have each adopted both of the top two most effective policies, along with at least eight other policies.

In 2007, China surpassed the United States as the largest emitter of greenhouse gases globally. “But the per capita emissions in the United States are more than double that of China,” Saikawa notes.

The Obama administration played a key role in securing the Paris Agreement, to keep global warming to no more than 2 degrees Celsius since the start of the Industrial Revolution.

“It will be interesting to hear the take of officials from the Trump administration this year,” Saikawa says. “U.S. coalitions from the state and city level are forming and they will likely have a strong presence at side events for COP23,” she adds. “Many groups are working at the local level around the world to try to meet the goal of the Paris Agreement.”

Emory is co-hosting an event on Thursday, November 16 at COP23, focused on ways to mitigate climate change impacts in the developing world. Saikawa will appear on a panel, along with John Seydel, director of sustainability for the city of Atlanta.

“We’ll be discussing how efforts at the city and state level in the United States might be replicated in other parts of the world,” Saikawa says.

This marks the third year in a row that Emory has sent a delegation to the U.N. climate talks.

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How lifeless particles can become 'life-like' by switching behaviors

Emory graduate student Guga Gogia slowly “salted” micron-sized particles into a vacuum chamber filled with plasma, creating a single layer of particles levitating above a charged electrode. He kept a low gas pressure, so the particles could move freely. “After a few minutes I could see with my naked eye that they were acting strangely," Gogia says.

By Carol Clark

Physicists have shown how a system of lifeless particles can become “life-like” by collectively switching back and forth between crystalline and fluid states — even when the environment remains stable.

Physical Review Letters recently published the findings, the first experimental realization of such dynamics.

“We’ve discovered perhaps the simplest physical system that can consistently keep changing behavior over time in a fixed environment,” says Justin Burton, Emory assistant professor of physics. “In fact, the system is so simple we never expected to see such a complex property emerge from it.”

Many living systems — from fireflies to neurons — switch behaviors collectively, firing on and then shutting off. The current paper, however, involved a non-living system: Plastic particles, tiny as dust specks, that have no “on” or “off” switches.

“The individual particles cannot change between crystalline and fluid states,” Burton says. “The switching emerges when there are collections of these particles — in fact, as few as 40. Our findings suggest that the ability for a system to switch behaviors over any time scale is more universal than previously thought.”

Watch a video to learn more and see the particles in action:


The Burton lab studies the tiny, plastic particles as a model for more complex systems. They can mimic the properties of real phenomena, such as the melting of a solid, and reveal how a system changes when it is driven by forces.

The particles are suspended in a vacuum chamber filled with a plasma — ionized argon gas. By altering the gas pressure inside the chamber, the lab members can study how the particles behave as they move between an excited, free-flowing state into a jammed, stable position.

The current discovery occurred after Emory graduate student Guram “Guga” Gogia tapped a shaker and slowly “salted” the particles into the vacuum chamber filled with the plasma, creating a single layer of particles levitating above a charged electrode. “I was just curious how the particles would behave over time if I set the parameters of the chamber at a low gas pressure, enabling them to move freely,” Gogia says. “After a few minutes I could see with my naked eye that they were acting strangely.”

From anywhere between tens of seconds to minutes, the particles would switch from moving in lockstep, or a rigid structure, to being in a melted gas-like state. It was surprising because the particles were not just melting and recrystallizing but going back and forth between the two states. 

“Imagine if you left a tray of ice out on your counter at room temperature,” Gogia says. “You wouldn’t be surprised if it melted. But if you kept the ice on the counter, you would be shocked if it kept turning back to ice and melting again.”

Gogia conducted experiments to confirm and quantify the phenomenon. The findings could serve as a simple model for the study of emerging properties in non-equillibrium systems.

“Switching is an ubiquitous part of our physical world,” Burton says. “Nothing stays in a steady state for long — from the Earth’s climate to the neurons in a human brain. Understanding how systems switch is a fundamental question in physics. Our model strips away the complexity of this behavior, providing the minimum ingredients necessary. That provides a base, a starting point, to help understand more complex systems.”

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$2 million NSF grant funds physicists' quest for optical transistors

"The ultimate goal is making it possible to devise all-optical computers and telecommunications," says Hayk Harutyunyan, left, with Ajit Srivastava. (Ann Borden, Emory Photo/Video)

By Carol Clark

The National Science Foundation awarded two Emory physicists a $2 million Emergent Frontiers grant, for development of miniaturized optical transistors to take computers and telecommunications into a new era.

“We are working to change some properties of light — such as making it travel in only one direction — by using atomically thin, two-dimensional materials,” says Ajit Srivastava, assistant professor of physics and principal investigator for the grant. “These novel materials are being touted as the next silicon. They could open the door to even smaller and more efficient electronics than are possible today.”

Srivastava’s co-investigators include Hayk Harutyunyan, also an assistant professor of physics at Emory, as well as scientists from Georgia State and Stanford universities.

“The ultimate goal is making it possible to devise all-optical computers and telecommunications,” Harutyunyan says.

A major revolution in telecommunications occurred in the 1950s, driven by the development of silicon semiconductors as miniature transistors to control the flow of electrical current. These transistors led to smaller, faster computers and paved the way for everything from flatscreen TVs to cell phones.

“They changed civilization,” Harutyunyan says. “Every year new computers would come out with faster processors as the transistors got tinier and more efficient. But about a decade ago this progress stopped, because these transistors cannot be made any smaller than about 15 nanometers and still function well.”

Meanwhile, the gradual replacement of copper wiring with fiber optics is speeding up transmissions between computers and other electronic devices and allowing for greater bandwidth. “When you send an email from Atlanta to Europe, the information is encoded into light and relayed by fiber optic cables running under the ocean,” Srivastava explains. “It’s super fast, because light is the fastest thing that you can imagine.”

Unlike in our everyday life, however, where the arrow of time moves in one direction, light photons operate at the quantum scale and can move back and forth. This lack of a fixed direction is called reciprocity. “Reciprocity in optics,” Srivastava says, “can best be described by a familiar observation: ‘If I can see you, you can see me.’”

Fiber optic cables use magnetic fields to break reciprocity and prevent light from reflecting off surfaces and creating “noise” in a signal. The required magnetic devices, known as optical isolators, are typically bulky and heavy because tiny magnets are not strong enough to do the job.

The Emory project aims to develop powerful nonreciprocal optical devices that are not based on magnets and can function at the nanoscale.

Srivastava’s lab is investigating the potential of transition metal dichalcogenides, or TMDs. TMDs are semiconductors within a new family of two-dimensional, extraordinarily thin materials. While the smallest feature of a current computer processor is 14 nanometers thick, a TMD monolayer is smaller than a single nanometer.

Harutyunyan’s lab, meanwhile, is exploring ways to make interactions between light and matter stronger through the use of metallic nano particles. Metals are shiny because of their free electrons that easily interact with light. The oscillations of these free electrons, called plasmons, allow metallic nano-particles to funnel large amounts of light into tiny dimensions.

A long-term goal of the project is to hybridize TMDs and metallic particles into nanomaterials that use laser fields to create the same light-guiding effects of magnetic fields. Such devices have the potential to be faster and cheaper and offer more precise control of the light-directing process. They would also be much smaller than existing optical isolators and transistors.

“Nano-science is an exciting area,” Srivastava says. “You can imagine the possibility of flexible cell phones or even wearable electronic membranes that would take the shape of your body.”

More powerful computers could also ramp up the ability of scientists to analyze massive datasets faster, Harutyunyan notes.

The Emory grant will also fund public outreach projects in Atlanta area schools. “We want people to understand the importance of fundamental science research,” Harutyunyan says. “And we want to inspire young people to think about science careers.

CDC funds Emory project to automate analysis of mixed strains of antibiotic-resistant bacteria

An electron micrograph shows human immune system cells attacking methicillin-resistant Staphylococcus aureus (MRSA). MRSA is an example of antibiotic-resistant bacteria that can occur in multiple strains in an infection, further complicating diagnosis, treatment and interventions.

By Carol Clark

The Centers for Disease Control and Prevention (CDC) awarded $380,000 to three Emory University faculty to develop and refine a promising technique to detect and respond to threats from drug-resistant pathogens.

The grant investigators include Lars Ruthotto and Ymir Vigfusson — both assistant professors in the Department of Mathematics and Computer Science — and Rebecca Mitchell, a visiting professor with a joint appointment in the Department of Mathematics and Computer Science and the Nell Hodgson Woodruff School of Nursing. 

The trio is developing a method to quickly and cost-effectively diagnose multiple strains of antibiotic-resistant bacteria within a single biological sample.

“This project harmonizes our different scientific specialties,” Vigfusson says. He is a computer scientist who develops software and programming algorithms that work at scale, while Ruthotto is a mathematician who focuses on solving inverse problems. Mitchell is a veterinarian and epidemiologist experienced in gathering biological samples and testing them for pathogens. 

Antibiotic-resistant infections are a growing national and global problem, causing at least two million illnesses and 23,000 deaths in the United States annually, according to the CDC.

The Emory grant is part of a $9 million package of CDC funding announced today, including awards to projects at 25 leading research institutions around the country that are exploring gaps in knowledge about antibiotic resistance and piloting innovative solutions in the healthcare, veterinary and agriculture industries. The work complements broader CDC efforts to support known strategies for protecting people and slowing antibiotic resistance, collectively known as the CDC Antibiotic Resistance Solutions Initiative.

The Emory project seeks to tame the complexity of analyzing multiple infections within a biological specimen, from a drop of blood to a fecal sample. In the case of a widespread outbreak of antibiotic-resistant E. coli for instance, it would be useful to quickly determine whether fecal samples contained multiple strains of the bacteria and what those strains were, in order to more rapidly trace the sources of the outbreak and design effective interventions.

It is costly and labor-intensive, however, to culture biological samples at the local level, and then send them to the CDC for testing. And if multiple strains of a pathogen are within a single sample, only some strains that are present may grow in the culture while other strains may be missed.

“It’s a challenge to deal with samples containing mixed strains of a pathogen in a lab setting,” Mitchell says. “You have to do a large amount of work to get the finer gradations of what species of pathogens are present, and in what proportions.”

The Emory researchers are striving to balance accuracy with the need to simplify and streamline the process. Their method eliminates labor-intensive, technical steps, such as culturing the sample. “We want to automate the process so that you need less expertise at the local level, and so that data coming from individual states can be easily integrated into a central system,” Mitchell explains.

They use multiple short polymorphic regions in the genome to look for genetic variations among the DNA templates present within a biological sample. In the case of antibiotic-resistant bacteria, the number of reference sites ranges between the hundreds to the thousands, depending on the specific bacteria targeted.

“We’ve developed an algorithm and software and mathematical models to rapidly run these comparisons and estimate the number of strains in a single sample, and the percentage of each,” Ruthotto says. “Now we are trying to quantify the accuracy of this estimate, which is a mathematical challenge. The grant gives us the resources to refine our method for real-world applications.”

The ultimate goal is to develop a system that will work not just on antibiotic-resistant bacteria, but for mixed-strains of any pathogen within a biological sample. In a separate project, for example, Mitchell and Vigfusson are applying the method to test for multiple strains of the malaria parasite within a blood sample.

“Quickly teasing apart mixed-strain samples is a big challenge in public health, and it’s essential in order to plan effective interventions,” Mitchell says.

“We’re using math and computer science to draw more information from a single biological sample than was previously practical,” Vigfusson says. “We hope that our method could turn into a work engine that helps to understand multiple-strain infections and makes an impact on public health.”

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Responding to climate change

By Martha McKenzie
Emory Public Health

Climate change. Partisan politicians debate its reality, and many citizens see it as a faraway threat, something that endangers the future of polar bears but not them personally.

The health effects of global warming, however, are already being felt. Extreme weather events such as wildfires, droughts, and flooding are becoming more frequent, resulting in more injuries, deaths, and relocations. Heat and air pollution are sending people with asthma and other respiratory ailments to the emergency room. Diseases carried by mosquitoes, fleas, and ticks are expanding their territory—dengue has become endemic in Florida, Lyme disease has worked its way up to Canada and over to California, and some fear that malaria may re-emerge in the U.S.

Tie these health burdens—which are only likely to worsen—with the current administration’s decision to pull out of the Paris climate agreement and dismantle environmental regulations, and the call to action becomes more urgent. “The federal government’s actions might be a headwind from a funding perspective, but they are also very much a tailwind from an inspiration and motivation perspective,” says Daniel Rochberg, an instructor in environmental health who worked for the U.S. State Department as special assistant to the lead U.S. climate negotiators under presidents Bush and Obama. “As others have said, ‘We are the first generation to feel the sting of climate change, and we are the last generation that can do something about it.’ We have to get busy doing something about it.”

Rollins School of Public Health has gotten busy. Faculty researchers are building the science of climate impacts, strategies for reducing greenhouse gas emissions, and approaches for increasing resilience to climate change. Climate@Emory, a university-wide organization of concerned students, faculty, and staff, is partnering with other academic institutions, industries, and governments to support education and climate remediation efforts. Through Climate@Emory’s initiative, Emory University is an accredited, official observer to the UN climate talks and has sent students and faculty to the climate conferences in Paris in 2015 and in Marrakech in 2016. And, of course, Rollins is educating the next generation of scientists who will be dealing with the fallout of today’s climate decisions.

“For environmental scientists, it’s a challenging climate,” says Paige Tolbert, O. Wayne Rollins Chair of Environmental Health. “That means we have to be creative, because we can’t step aside and wait four years. It’s more critical than ever that we keep moving forward and make whatever contributions we possibly can.”

Read more in Emory Public Health.

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