Tundra Fires Could Accelerate Climate Warming

After a 10,000-year absence, wildfires have returned to the Arctic tundra, and a new study shows that their impact on climate. (Credit: © gburba / Fotolia)

Science Daily — After a 10,000-year absence, wildfires have returned to the Arctic tundra, and a University of Florida study shows that their impact could extend far beyond the areas blackened by flames.

In a study published in the July 28 issue of the journal Nature, UF ecologist Michelle Mack and a team of scientists including fellow UF ecologist Ted Schuur quantified the amount of soil-bound carbon released into the atmosphere in the 2007 Anaktuvuk River fire, which covered more than 400 square miles on the North Slope of Alaska's Brooks Range. The 2.1 million metric tons of carbon released in the fire -- roughly twice the amount of greenhouse gases put out by the city of Miami in a year -- is significant enough to suggest that Arctic fires could impact the global climate, said Mack, an associate professor of ecosystem ecology in UF's department of biology.

"The 2007 fire was the canary in the coal mine," Mack said. "In this wilderness, hundreds of miles away from the nearest city or source of pollution, we're seeing the effects of a warming atmosphere. It's a wake-up call that the Arctic carbon cycle could change rapidly, and we need to know what the consequences will be."

Smoke from the fire pumped greenhouse gases into the atmosphere, but that's just one part of a tundra fire's potential impact. The fire also consumed up to 30 percent of the insulating layer of organic matter that protects the permafrost beneath the tundra's shrub- and moss-covered landscape.

In a pine forest, fire would burn up leaf litter on the ground, but not the soil beneath. Because the Arctic tundra has a carbon-rich, peaty soil, however, the ground itself is combustible, and when the fire recedes, some of the soil is gone. In a double whammy, the vulnerable permafrost is not only more exposed, but also covered by blackened ground, which absorbs more of the sun's heat and could accelerate thawing.

"When the permafrost warms, microbes will begin to decompose that organic matter and could release even more carbon that's been stored in the permafrost for hundreds or thousands of years into the atmosphere," Mack said. "If that huge stock of carbon is released, it could increase atmospheric carbon dioxide drastically."

The study shows how isolated fires can have a widespread impact, said University of Alaska biology professor Terry Chapin. "When you think about the massive carbon stocks and massive area of tundra throughout the world, and its increasing vulnerability to fire as climate warms, it suggests that fire may become the dominant factor that governs the future carbon balance of this biome," Chapin said. "The paper by Michelle and her colleagues raises this possibility for the first time. It presents a very different perspective on the way in which climate change may affect this biome in the future."

Using radiocarbon dating, co-author Schuur and researchers from the University of Alaska Fairbanks, the Alaska Fire Service and Woods Hole Marine Biological Laboratory, found that carbon up to 50 years old had been burned in the 2007 fire.

Mack also developed a new method that can now be used by other tundra researchers to measure soil loss. By comparing the tussocks of sedge plants, which resprout after a fire, Mack was able to quantify soil heights and densities before and after the burn.

Mack hopes her findings will open a dialogue about how tundra fires are managed. Because the Anaktuvuk River fire was in a wilderness area, it was not suppressed or contained. With better data on the long-term impact of tundra fire on global climate warming, Mack says, putting out these fires might become more of a priority.

"This fire was a big wake-up call, and it can happen again, not just in Alaska but in other parts of the Arctic, like Canada and Russia," Mack said. "Suppressing a fire in the wilderness is costly, but what if the fire causes the permafrost to melt? We need to have that discussion."

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How to Seize the 85 million Jobs Bonanza

SUBMITTED BY JUSTIN YIFU LIN 

Remember the famous joke about an economist who believes so much in rational expectation theory that he would not pick up a $100 dollar bill off the sidewalk under the pretense that if it were actually there someone would have already picked it up? A similar excuse may be invoked to justify why low-income countries that are currently facing high underemployment are not organizing themselves to seize the extraordinary bonanza of the 85 million manufacturing jobs that China will have to shed in the coming years because of fast rising wages for unskilled workers.

Economic development is a process of continuous industrial and technological upgrading in which each country, regardless of its level of development, can succeed if it develops industries that are consistent with its comparative advantage, determined by its endowment structure. As I explained in an earlier blog post for China to maintain GDP growth of nearly 10 per cent a year in the coming decades, it must keep moving up the value chain and relocate many of its existing labour-intensive manufacturing industries to countries where wage differentials are large enough to ensure competitiveness in global production networks.

The question is why the parties that would benefit enormously from these potential deal—Chinese firms and lower-income country governments—are not yet organizing themselves to seize that unprecedented win-win opportunity for fostering global prosperity. From my frequent interactions with policymakers in Africa, Asia, and elsewhere where wages are still relatively low, I know that they would all be interested in building such partnerships. I have also had extensive discussions with Chinese business leaders and local government officials about the challenges they are facing, most notably the rapid rising wages and the exchange rate appreciation. They too expressed a clear interest in finding places where they could relocate production and remain competitive. What then prevents these lucrative and mutually profitable deals from happening? Why are so few business leaders and policymakers seizing the opportunities of these 85 million jobs if they are truly available in the coming years? Why are people ignoring the huge pile of so many $100 bills on the sidewalks?

To be fair, some deals are taking place here and there, with individual foreign firms linking up with African entrepreneurs to develop various labour-intensive manufacturing industries. But the scale and size of these initiatives remain relatively small. Moreover, the main motivation of Chinese, Indian and other foreign businessmen involved in these early ventures is typically to exploit the large price premium for their products in these markets. And because these new locations are not yet true exporting bases, only a limited number of manufacturing jobs are actually being relocated or created. It is not that the Chinese industrialists are ignoring the $100 bills on the sidewalks: many of them are simply hesitant to relocate abroad, especially to Africa. They usually raise four issues: (i) social and political instability; (ii) differences in culture and labour laws; (iii) poor logistics; and (iv), the lack of adequate infrastructure and business conditions. These concerns add to the risks of their investments, increase the transaction costs of their operations, and outweigh the potential benefits of low labour costs in Africa and other low-income countries.

How to deal with such problems? The first two issues could be mitigated through the commitment and support of recipient governments; the latter two could be addressed effectively through the development of cluster-based industrial zones.  To be competitive in a global production network, firms should choose industries that are consistent with a country’s comparative advantage so as to reduce the factor costs of production. Furthermore, it is necessary to reduce transaction-related costs, such as good access to large input suppliers, logistics, equipment maintenance, marketing, and transportation. Cluster-based industrial zones largely explain the success of garment, furniture, footwear, consumer electronics, motorcycle and many other labour-intensive manufacturing industries in China and other dynamic growing East Asian economies.

While it may seem counter-intuitive for firms that compete intensely among themselves to willingly locate their operations in the same place, there is a strong economic rationale for it. Paul Krugman and other proponents of the new trade theory and the new economic geography have shown that there is a self-reinforcing character to spatial concentration. Business concentration takes place and is sustained because of some form of agglomeration economies in which spatial concentration itself creates a favorable economic environment that supports further or continued concentration. In such situations, firms benefit from knowledge spillovers, a market for specialized skills, and backward and forward linkages (good access to large input suppliers, logistics, privileged network with customers, etc.). These agglomeration benefits reduce the individual firm’s transaction costs, and increase the competitiveness of a nation’s industry, compared with the same industry in other countries at a similar level of development as argued by Michael Porter.

It could pay off handsomely for policymakers in Africa and other low-income countries to carefully identify sectors that are consistent with the comparative advantages of their countries, demonstrating commitment and proactively adopting a cluster-based industrial zone approach to attract the relocation of a large number of Chinese firms in the identified clusters in China to their countries. In other words, many low-income countries’ policymakers could pick up a substantial number of the many $100 bills on the sidewalk, and attract some of these 85 million Chinese manufacturing jobs that their countries’ desperately needs. The quicker they adopt this approach, the sooner will their countries grow dynamically like the East Asian economies.

 

Cheap Plastic Made from Sugarcane

Crude replacement: This Brazilian sugarcane could supersede oil for making plastic.
Credit: Dow Chemical

ENERGY

Dow Chemical is building a plant to make polyethylene from sugarcane at costs that rival petrochemical production.

• BY KEVIN BULLIS

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Making plastic from sugar can be just as cheap as making it from petroleum, says Dow Chemical. The company plans to build a plant in Brazil that it says will be the world's largest facility for making polymers from plants. 

The project will begin with the construction of a 240-million-liter ethanol plant, a joint venture with Mitsui, that is set to begin later this year. By the beginning of next year, Dow will finish engineering plans for facilities that will convert that ethanol into hundreds of thousands of metric tons of polyethylene, the world's most widely used plastic.

Bio-based chemicals production has grown quickly in recent years, but it still represents just 7.7 percent of the overall chemicals market. Production has been limited in many cases to specialty chemicals or niche products. But Dow now says chemicals made from plant feedstocks may be ready to compete head-to-head with petrochemicals made in large volumes.

Most large-volume chemicals are made from petroleum. About 80 million tons of polyethylene are made annually around the world. But high oil prices have increased the costs of petrochemicals. And in Brazil, long-standing government support for sugarcane ethanol production has allowed the industry to drive down costs, making ethanol competitive with fossil fuels. Making polyethylene from sugar "would not necessarily be attractive in other regions," says Luis Cirihal, Dow's director of renewable alternatives and business development for Latin America.

The technology for converting ethanol into ethylene, the precursor for polyethylene, is not new. "The dehydration process for converting ethanol to ethylene has been known since the 1920s. The only thing that's really new here is the scale," Cirihal says. The new plant will have a polyethylene production capacity comparable to production at a petrochemical plant. Though the exact production levels aren't yet settled, they will be on the order of "what you have heard before," he says, referring to a proposed Dow project that would have made 350,000 metric tons of polyethylene from sugarcane. (That proposal relied on a partnership that ended as a result of the recession.) It will be bigger than a 200,000-ton sugarcane-to-polyethylene plant operated by Brazil-based Braskem.

The new plant won't be the first time Dow has invested significantly in bio-based plastics. A decade ago, it partnered with Cargill to make corn-based plastics. But Dow pulled out of that venture in 2005 after the market for the bioplastic failed to take off. Cirihal says that Dow is now taking a different approach. The earlier plastic was a new material, and proved difficult to market and distribute. He says that's why Dow decided to make a common material with an established market this time. The sugarcane-based polyethylene will perform just as well as oil-based polyethylene, he says.

Cirihal says Dow is keeping costs down by doing every part of the process, from growing the sugarcane to producing the polymers. This makes it possible, for example, to provide energy to run the plant with biomass left over from producing sugar from sugarcane. While he says the plastics produced will be competitive with petrochemicals, he also says the company hopes to charge more for the product because of the significant demand for low-carbon, sustainable materials.

The Mechanics of Blast Injuries

Two studies mimic the effects of traumatic brain injury in cells, helping to explain how explosions harm soldiers' brains.

• BY COURTNEY HUMPHRIES

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Under fire: Brain injuries caused by improvised explosive devices, like the one that destroyed this Humvee, are increasingly common among soldiers.
Credit: Department of Defense

Scientists have discovered a mechanism underlying the type of brain injury that soldiers often suffer as a result of roadside explosions in Iraq and Afghanistan. The work could point the way toward early treatment for these acute blast injuries by identifying potential drug targets.

Two new papers from the Disease Biophysics Group at Harvard's School of Engineering and Applied Sciences and Wyss Institute for Biologically Inspired Engineering, led by Kevin "Kit" Parker, use tissue-engineering techniques to model the physical and biochemical effects of traumatic brain injury (TBI) in the brain and blood vessels. Parker says the work represents a first step toward a "TBI on a chip" that could be used to screen for drugs to treat blast-injured soldiers before long-term damage sets in.

TBI induced by blasts from improvised explosive devices and rocket-propelled grenades is the most common injury among soldiers in Iraq and Afghanistan. Even mild TBI is an insidious injury, because it damages the brain in ways that aren't immediately apparent and that physicians currently can do little to treat. It's commonly believed that the injury damages the brain by stretching neurons to their breaking point, ripping small holes in the cell membrane that eventually kill the cells. But Parker says his team found that it wasn't necessary to harm the membrane to induce TBI-like injuries in the cell.

Both papers focus on integrins, a type of cell-membrane protein that translates the mechanical forces of injury into internal changes in the cell. The researchers subjected cells to brief, abrupt forces. Such systems have been used in the past, but Parker's team used forces that weren't powerful enough to physically rip the cell. They found that this could cause the same kinds of structural changes in both neurons and blood vessel cells as those seen in the brains of people with TBI.

David Hovda, who directs the Brain Injury Research Center at University of California Los Angeles, says the studies will lead people who have been working on TBI to think about these injuries in a new way. He also believes that the findings could potentially apply to people with other kinds of brain injuries, although the difference between blasts and other traumas is currently controversial. However, Hovda says that like other studies on isolated cells, they may or may not really capture what's happening in the brain. "Trauma is the most complicated form of injury, and the brain is the most complicated organ," he says. He says that more studies and autopsies on wounded soldiers must be conducted to understand the effects of blasts in human brains.

In one of the papers, published in today in PLoS One, the researchers attached magnetic beads to integrin complexes that act as a kind of structural anchor in cells, along the axons of neurons. They found that just a small force applied to the beads was necessary to injure axons. Furthermore, the forces on one bead would propagate through the cell's skeleton down another axon, causing the distant axon to break or be injured. Parker says the propagation of forces through neurons explains why damage to axons can be seen even far from the injury site in human brains.

The other paper, published last week in Proceedings of the National Academy of Sciences, shows that integrins can also mediate a problem called cerebral vasospasm, a narrowing of blood-vessel openings that begins days to months after a blast injury. Parker explains that while vasospasm can occur when blood vessels break and bleed out, sometimes there is no bleeding and another process must be in play. His team engineered arteries from blood-vessel cells and studied the effects of blast-like stretching. "We found that within 24 hours, the blast had induced the flip of a genetic switch," he says. That creates chemical and physical changes characteristic of cells in cerebral vasospasm.

In both the neurons and the blood-vessel cells, treating cells with a drug that inhibits a protein activated by integrins lessened the injury. Parker believes that targeting this or similar chemical pathways could be a way to treat soldiers directly after blasts, in order to prevent some of the slower biochemical effects that follow from the initial trauma.

Parker, a major in the U.S. Army who served in Afghanistan, normally works on other biophysics problems but got involved in the project after spending time on a battlefield with Colonel Geoffrey Ling, a U.S. Army neurologist specializing in brain trauma; Ling is now a program manager at the Defense Advanced Research Projects Agency (DARPA), where he directs efforts to fund research into the science of TBI. Because it's very difficult to know what's happening in the brains of injured soldiers, Parker says, we need another way of studying the problem: "If you don't build models for IED blasts, then it's going to be difficult to get people to come into this field."

A Light Switch for Bacterial Infections

Bacteria blues: Bacteria collected in the bottom of the tube on the right have been labeled with a blue imaging agent.
Credit: Niren Murthy

BIOMEDICINE

A new contrast agent could detect bacteria on medical implants, and help doctors decide how to treat infection.

• BY KATHERINE BOURZAC

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A new contrast agent that targets microbes can be used to illuminate bacterial infections in living animals. It could ultimately enable doctors to safely spare more of a limb during amputations.

It's usually clear when a patient has a bacterial infection and needs to be treated with antibiotics, says Jason Bowling, director of epidemiology at the University of Texas Health Science Center at San Antonio, who was not involved with developing the imaging agent. But sometimes an infection is more difficult to diagnose. For example, it can be difficult to tell when a patient who has pain at the site of a hip or knee replacement has an infection. This sometimes leads doctors to prescribe antibiotics when they aren't necessary.

An imaging scan capable of detecting bacteria would quickly answer the question, sparing uninfected patients from unnecessary antibiotics or even from surgery to remove the implant. Where there is an infection and the implant is removed, imaging could help ensure that no new hardware is implanted until the infection has been completely cleared.

It's challenging to image infections because many of the molecules used to target bacteria can accumulate in tissue that is merely inflamed rather than infected, says Niren Murthy, professor of biomedical engineering at Georgia Tech, who was involved with developing the new agent. The new imaging agent is taken up by bacteria in large quantities, but it won't stick around in other tissue. "We had to find something very specific to bacteria," he says.

Murthy's group stole a trick from a group of viruses that gets its genome inside bacteria by attaching it to a bacterial food source, a carbohydrate called maltohexaose. Bacteria have proteins on their cell walls whose job is to bring maltohexaose inside the cell, and this happens even if that maltohexaose is attached to an imaging agent. Animal cells don't have these proteins, so they don't take up the contrast agent.

 There are already two bacterial imaging agents on the market for use in preclinical research. But these are not as sensitive or as versatile as the Georgia Tech probe, says W. Matthew Leevy, professor of chemistry and director of biological imaging research at the University of Notre Dame. Those earlier imaging agents work by a different mechanism—they stick to bacterial cell walls rather than accumulate inside the cell. The Georgia Tech probe is two orders of magnitude more sensitive than any made in the past, which means it can detect much smaller populations of bacteria. Leevy says it should be compatible with a wide array of imaging technologies, including MRI, PET, and fluorescence imaging.

In a paper published online in the journal Nature Materials this week, Murthy describes imaging bacterial infections in living mice using the new contrast agent—maltohexaose attached to a fluorescent protein. Fluorescent imaging is useful for animal studies, but the method can't be used to visualize the deep tissues of the body because the light simply cannot get out. Murthy is now coupling maltohexaose with imaging agents suitable for imaging with PET.

It will be critical to make the new contrast agent compatible with imaging technologies commonly found in hospitals, says Bowling, who runs a clinic where he monitors patients with bone infections. He says it's often difficult to decide whether a patient has recovered and can be taken off the drugs. "There's not a lot of data on when to stop treatment, and you can't tell if you've truly cleared an infection or not," he says. Other uses for the imaging agent might include helping doctors determine whether a diabetic's foot problems are due to infection, and visualizing the extent of an infection in patients who need an amputation.

Leevy says he expects the agent to be available to researchers soon, but he says it could be difficult to bring the imaging technology into the clinic. While it could make a big difference for some patients, he says, the narrow potential market could discourage a company from making the large investment necessary to bring the agent through clinical trials.

Glucose Meter Can Detect Cocaine, Uranium in Blood

Sugar sensor: Researchers used an unmodified Accu-Chek Aviva glucose monitor to measure a variety of substances.
Credit: Accu-Chek

BIOMEDICINE

Creative chemistry lets an inexpensive, off-the-shelf meter measure a variety of medically important targets.

• BY KENRICK VEZINA

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Researchers have shown that an off-the-shelf glucose meter can be used to test blood samples for a variety of substances, including cocaine, the pathogen-related protein interferon, the biochemical adenosine, and traces of uranium. The ability to measure such medically important targets without expensive lab testing could be particularly vital in developing countries.

The researchers modified the chemistry of blood samples in order to use glucose concentration as a proxy for detecting the concentration of these substances. The research was conducted by Yu Xiang and Yi Lu at the University of Illinois at Urbana-Champaign.

"There's an elegant simplicity to their repurposing," says Kevin Plaxco, professor of biochemistry at the University of California, Santa Barbara. "The development of a general sensing platform with the convenience and form-factor of the home glucose meter is the holy grail of biosensor research," he says.

To achieve this, Xiang and Lu first modify a sample (typically blood) with a solution containing microscopic magnetic beads. Attached to these beads is a piece of DNA that binds to a desired target, as well as invertase, an enzyme that drives the breakdown of sucrose into glucose. When the target binds to the DNA, it releases invertase from the magnetic bead. Once the target is bound to the DNA—a process that takes anywhere from seconds to minutes, depending on the target—the solution is exposed to a magnet, which pulls out the remaining magnetic beads, which hold the unreleased invertase. The solution is then mixed into another that contains sucrose. The released invertase breaks the sucrose down into glucose—and the concentration of glucose is directly related to the concentration of the target. In a final step, the solution is put onto a test strip and into the glucose meter, giving a reading of the concentration of the target substance in the original sample.

"This paper sets an excellent example in combining novel sciences with existing technologies for translational research and development," says Weihong Tan, a chemistry professor at the University of Florida. "This will revolutionize the field of biosensors and push biosensors to be practically useful in personalized medicine and in medical diagnosis."

Colin Campbell, a professor of chemistry at the University of Edinburgh, says Xiang and Lu have "steered around one of the common questions asked of such technologies: 'Can you really make it small enough and simple enough that anyone could use it?' " Furthermore, he says, "It is important and impressive that the authors have demonstrated detection in complex samples like blood."

However, "several hurdles should be overcome if this technique is commercialized," saysJaebum Choo, a professor of bio-nano engineering at Hanyang University. "First, there are not many target contents which can be captured by specific sequences of DNA." He also sees the magnetic separation, which adds another step to the process, as a problem, calling it "another hurdle to be considered in the integration process for the commercialization."

Lu hopes to make the process simpler by replacing the magnet with a filter that would separate the unreleased invertase from the mixture as it is injected into the sucrose solution via syringe. He hopes to see his research lead to commercially available chemical testing kits. "The science and technology are already well developed," he says, "and there are only several engineering challenges that need to be overcome to reach this goal."