The work, presented online May 27 in Nature Geoscience, shows that once the angle of a slope exceeds 30 degrees – whether from uplift, a rushing stream carving away the bottom of the slope or a combination of the two – landslide erosion increases significantly until the hillside stabilizes.

The Landsat satellite image at left shows a huge lake on the Tsangpo River behind a dam created by a landslide (in red, lower right of the lake) in early 2000. The image at right shows the river following a catastrophic breach of the dam in June 2000.

U.S. Geological Survey/NASA

"I think the formation of these landscapes could apply to any steep mountain terrain in the world," said lead author Isaac Larsen, a University of Washington doctoral student in Earth and space sciences.

The study, co-authored by David Montgomery, a UW professor of Earth and space sciences and Larsen's doctoral adviser, focuses on landslide erosion along rivers in the eastern Himalaya region of southern Asia.

The scientists studied images of more than 15,000 landslides before 1974 and more than 550 more between 1974 and 2007. The data came from satellite imagery, including high-resolution spy satellite photography that was declassified in the 1990s.

They found that small increases in slope angle above about 30 degrees translated into large increases in landslide erosion as the stress of gravity exceeded the strength of the bedrock.

"Interestingly, 35 degrees is about the same angle that will form if sand or other coarse granular material is poured into a pile," Larsen said. "Sand is non-cohesive, whereas intact bedrock can have high cohesion and should support steeper slopes.

"The implication is that bedrock in tectonically active mountains is so extensively fractured that in some ways it behaves like a sand pile. Removal of sand at the base of the pile will cause miniature landslides, just as erosion of material at the base of hill slopes in real mountain ranges will lead to landslides."

The researchers looked closely at an area of the 150-mile Tsangpo Gorge in southeast Tibet, possibly the deepest gorge in the world, downstream from the Yarlung Tsangpo River where the Po Tsangpo River plunges more than 6,500 feet, about 1.25 miles. It then becomes the Brahmaputra River before flowing through the Ganges River delta and into the Bay of Bengal.

Map by Wikimedia Commons user Pfly.

The scientists found that within the steep gorge, the rapidly flowing water can scour soil from the bases, or toes, of slopes, leaving exposed bedrock and an increased slope angle that triggers landslides to stabilize the slopes.

From 1974 through 2007, erosion rates reached more than a half-inch per year along some 6-mile stretches of the river within the gorge, and throughout that active landslide region erosion ranged from 0.15 to 0.8 inch per year. Areas with less tectonic and landslide activity experienced erosion rates of less than 0.15 inch a year.

Images showed that a huge landslide in early 2000 created a gigantic dam on a stretch of the Po Tsangpo. The dam failed catastrophically in June of that year, and the ensuing flood caused a number of fatalities and much property damage downstream.

That event illustrates the processes at work in steep mountain terrain, but the processes happen on a faster timescale in the Tsangpo Gorge than in other steep mountain regions of the world and so are more easily verified.

"We've been able to document the role that landslides play in the Tsangpo Gorge," Larsen said. "It explains how steep mountain topography evolves over time."

The work was financed by NASA, the Geological Society of America, Sigma Xi (the Scientific Research Society) and the UW Quaternary Research Center and Department of Earth and Space Sciences.

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For more information, contact Larsen at 206-265-0473 or larseni@uw.edu, or Montgomery at 206-685-2560 or dave@ess.washington.edu.

A University of Washington mathematician is part of an international team working to understand invisibility and extend its possible applications. The group has now devised an amplifier that can boost light, sound or other waves while hiding them inside an invisible container.

"You can isolate and magnify what you want to see, and make the rest invisible," said corresponding author Gunther Uhlmann, a UW mathematics professor. "You can amplify the waves tremendously. And although the wave has been magnified a lot, you still cannot see what is happening inside the container.”

The findings are published online this week in the Proceedings of the National Academy of Sciences.

As a first application, the researchers propose manipulating matter waves, which are the mathematical description of particles in quantum mechanics. The researchers envision building a quantum microscope that could capture quantum waves, the waves of the nanoworld. A quantum microscope could, for example, be used to monitor electronic processes on computer chips.

The authors dubbed their system "Schrödinger's hat," referring to the famed Schrödinger's cat in quantum mechanics. The name is also a nod to the ability to create something from what appears to be nothing.

"In some sense you are doing something magical, because it looks like a particle is being created. It's like pulling something out of your hat," Uhlmann said.

Matter waves inside the hat can also be shrunk, though Uhlmann notes that concealing very small objects "is not so interesting."

A matter wave hitting a Schrodinger's hat. The wave inside the container is magnified. Outside, the waves wrap as if they had never encountered any obstacle.

G. Uhlmann, U. of Washington

Uhlmann, who is on leave at the University of California, Irvine, has been working on invisibility with fellow mathematicians Allan Greenleaf at the University of Rochester, Yaroslav Kurylev at University College London in the U.K., and Matti Lassas at the University of Helsinki in Finland, all of whom are co-authors on the new paper.

The team helped develop the original mathematics to formulate cloaks, which must be realized using a class of engineered materials, dubbed metamaterials, that bend waves so that it appears as if there was no object in their path. The international team in 2007 devised wormholes in which waves disappear in one place and pop up somewhere else.

For this paper, they teamed up with co-author Ulf Leonhardt, a physicist at the University of St. Andrews in Scotland and author on one of the first papers on invisibility.

Recent progress suggests that a Schrodinger’s hat could, in fact, be built for some types of waves.

"From the experimental point of view, I think the most exciting thing is how easy it seems to be to build materials for acoustic cloaking," Uhlmann said. Wavelengths for microwave, sound and quantum matter waves are longer than light or electromagnetic waves, making it easier to build the materials to cloak objects from observation using these phenomena.

"We hope that it's feasible, but in science you don't know until you do it," Uhlmann said. Now that the paper is published, they hope to find collaborators to build a prototype.

The research was funded by the National Science Foundation in the U.S., the Engineering and Physical Sciences Research Council and the Royal Society in the U.K., and the Academy of Finland.

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For more information, contact Uhlmann at 206-543-1946 or gunther@math.washington.edu. He will be out of the country starting Wednesday, May 30 and best reached via email. Uhlmann is on leave at UC Irvine through the end of June.

University of Washington bioengineers have developed the first structure to grow small human blood vessels, creating a 3-D test bed that offers a better way to study disease, test drugs and perhaps someday grow human tissues for transplant.

The findings are published online this week in the Proceedings of the National Academy of Sciences.

"In clinical research you just draw a blood sample," said first author Ying Zheng, a UW research assistant professor of bioengineering. "But with this, we can really dissect what happens at the interface between the blood and the tissue. We can start to look at how these diseases start to progress and develop efficient therapies."

Researchers made a functional microvessel that spells the letters "UW." The white bar measures 100 micrometers, about the width of a human hair.

Y. Zheng, U. of Washington

During a period of two weeks, the endothelial cells grew throughout the structure and formed tubes through the mold's rectangular channels, just as they do in the human body.

When brain cells were injected into the surrounding gel, the cells released chemicals that prompted the engineered vessels to sprout new branches, extending the network. A similar system could supply blood to engineered tissue before transplant into the body.

After joining the UW last year, Zheng collaborated with the Puget Sound Blood Center to see how this research platform would work to transport real blood.

Engineered microvessels can form bends and T-junctions, like this one. The blue dots are the nuclei of the cells in the vessel walls, and the red lines are the cell junctions. Smooth muscle cells (green) wrap and tighten around the vessels, just as they do in the human body.

Y. Zheng, U. of Washington

The engineered vessels could transport human blood smoothly, even around corners. And when treated with an inflammatory compound the vessels developed clots, similar to what real vessels do when they become inflamed.

The system also shows promise as a model for tumor progression. Cancer begins as a hard tumor but secretes chemicals that cause nearby vessels to bulge and then sprout. Eventually tumor cells use these blood vessels to penetrate the bloodstream and colonize new parts of the body.

When the researchers added to their system a signaling protein for vessel growth that's overabundant in cancer and other diseases, new blood vessels sprouted from the originals. These new vessels were leaky, just as they are in human cancers.

"With this system we can dissect out each component or we can put them together to look at a complex problem. That's a nice thing—we can isolate the biophysical, biochemical or cellular components. How do endothelial cells respond to blood flow or to different chemicals, how do the endothelial cells interact with their surroundings, and how do these interactions affect the vessels' barrier function? We have a lot of degrees of freedom," Zheng said.

The system could also be used to study malaria, which becomes fatal when diseased blood cells stick to the vessel walls and block small openings, cutting off blood supply to the brain, placenta or other vital organs.

"I think this is a tremendous system for studying how blood clots form on vessels walls, how the vessel responds to shear stress and other mechanical and chemical factors, and for studying the many diseases that affect small blood vessels," said co-author Dr. José López, a professor of biochemistry and hematology at UW Medicine and chief scientific officer at the Puget Sound Blood Center.

Future work will use the system to further explore blood vessel interactions that involve inflammation and clotting. Zheng is also pursuing tissue engineering as a member of the UW's Center for Cardiovascular Biology and the Institute for Stem Cell and Regenerative Medicine.

Other co-authors are UW physics senior Samuel Totorica; Abraham Stroock, Michael Craven, Nak Won Choi, Michael Craven, Anthony Diaz-Santana and Claudia Fischbach at Cornell; Junmei Chen at the Puget Sound Blood Center; and Barbara Hempstead at Weill Cornell Medical College.

The research was funded by the National Institutes of Health, the American Heart Association, the Human Frontier Science Program and Cornell University.

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For more information, contact Zheng at 206-543-3223 or yingzy@uw.edu.

Organized by staff with Conservation Magazine and the University of Washington Department of Biology, the event is meant to appeal to a mix of students, scientists and other citizens of Puget Sound.

"We want people to come away from this event with a sense that conservation isn't just about stopping bad things from happening, but also about starting good things. They will get a glimpse of the kind of environmental innovations that are possible when we include engineers, architects, cooks and entrepreneurs in the environmental conversation," said Estella Leopold, UW professor emeritus of biology and an event host. "It turns out that environmental inspiration can be found in the most unexpected places."

The event will be from 10 a.m. to 4 p.m. Saturday, June 2, at Seattle's Town Hall and will feature 11 speakers talking about food, agriculture, built environments, energy, technology and business. Two are from the UW, the rest are with other U.S. and European institutions and organizations. Veteran science journalists David Malakoff with Science magazine and John Nielsen, a former environmental correspondent with National Public Radio, will guide discussions audience discussions.

"This event is not only about listening to the speakers – it’s also about listening to the audience," said Dee Boersma, UW professor of biology and co-organizer of the event. For example, Earthfix, a media project of Northwest public radio and television stations, will host a digital story booth where participants can share their thoughts and stories about environmental issues.

Now is the time for this kind of regional event, Boersma said.

"The Puget Sound region and the UW are emerging hubs for environmental innovation," she said. "We have a tremendous combination of interests and expertise here—environmental concern, technological know-how, and business entrepreneurship. This event mixes these communities up and brings smart people together to imagine a greener future."

Winter 2012 edition

Tickets can be purchased online for $50 – $25 for students– and include a catered lunch and a one-year subscription to Conservation Magazine, a quarterly UW publication distributed in 58 countries. There will be a limited number of tickets available at the door.

Major sponsors of the event with Conservation Magazine are the Bullitt Foundation, John D. and Catherine T. MacArthur Foundation, UW College of Arts and Sciences and UW College of the Environment. Fifteen other UW and community organizations are partners.

"Just as TED originally brought to the web ideas worth spreading about technology, entertainment and design, we hope to launch something similar for the environment," said UW's Kathryn Kohm, editor of Conservation Magazine and the other co-organizer of the remix event.

For more information contact Lindsey Doermann, doermann@uw.edu, 206-221-5292.

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For more information, news media can contact:
Boersma, 206-616-2185, boersma@uw.edu
Kohm, 206-685-4724, kkohm@uw.edu

A Tokyo museum book contains page after page of the strings of DNA code letters A,G,C and T found in the human genome. A single letter change might influence health risks.

Ben Casey

“This is a dramatic example of how recent human history has profoundly shaped patterns of genetic variation,” said Joshua Akey, University of Washington associate professor of genome sciences and a senior author of the study. His lab studies the genetic architecture behind differences among humans (as well as among other species) and the mechanisms of evolutionary change.

Although so-called single nucleotide variants are rare, they may influence a person’s resistance or susceptibility to common diseases, like heart or lung trouble or blood problems. The rarity of each specific variation means that scientists will often need to study DNA samples from very large numbers of people to draw any genetic links to these disorders. Researchers already realize that commonly occurring gene variants have only a modest role in the complex medical conditions with the most public health repercussions.

In this week’s paper, “Evolution and Functional Impact of Rare Coding Variations from Deep Sequencing of Exomes,” investigators described their study of the protein-coding sections of genomes from almost 2,440 individuals. The participants were 1,351 people of European extraction and 1,088 of African ancestry.

The study is a first step toward understanding how rare genetic variants contribute to some of the leading chronic illness causes of death in the world. It was conducted as part of the mission of the Seattle GO at the University of Washington and the Broad GO at Harvard University and MIT, both funded by the National Institute of Health’s National Heart Lung and Blood Institute Exome Sequencing Project. The exome consists of the protein-coding regions of the genome.

The overall project encompasses a great many individuals who have distinct traits, such as heart attacks before old age, strokes, or a high body mass index, to discover the genes and molecular mechanisms behind these conditions. Low cost, rapid sequencing of whole genomes is on its way to becoming clinically feasible. The information gleaned would be more useful if statistical and experimental methods could more accurately identify gene variations that regulate biological processes and produce functionally significant proteins. Such methods would link gene variations to disease causes and provide information for preventing and treating diseases.

The other senior author of the paper from the Exome Sequencing Project is Michael J. Bamshad, University of Washington professor of pediatrics in the Division of Genetic Medicine. Researchers from eight institutions across the nation collaborated.

The group sequenced and compared 15,585 human protein-coding genes. They located more than a half-million single-letter DNA code variations in their sample populations. The majority of these variations arose recently in human evolutionary history and so were rare, novel, and specific either to the African or the European study populations, the researchers discovered.

The researchers went on to pick just those single-letter variations in the DNA that might affect the functions of proteins. Alterations in protein functions are among the key ways genetic differences spin into disease traits. They estimated that a little more than 2 percent of the approximately 13,600 single nucleotide variations each person carried, on average, influenced the function of about 313 genes per genome. More than 95 percent of the single-letter code changes predicted to be functionally important were rare in the overall study population.

How did so many rare variations affecting protein function arise in the human genetic code? The researchers suggest that this excess of rare variations is due to a combination of demographic and evolutionary forces. Both European and African populations grew exponentially beginning around 10,000 years ago, but in the past 5,000 years growth rates accelerated leading to the billions of people living today.

The dramatic recent increase in population size has therefore profoundly influenced the spectrum of protein-coding variation present in humans. The scientists calculated the mean average of novel, single-letter code variations in their study subjects: 549 per individual overall. People of African descent had about twice the number of new variations compared to those of European descent, or 762 versus 382.

The researchers measured the effects of natural selection on rare coding variation. To do so, they also brought in genetic details from genes highly specific to humans relative to chimps and macaques to look for what are called “selective sweeps.” A selective sweep occurs when natural selection increases the frequency of a beneficial variant in a population. The beneficial variant doesn’t travel alone. Nearby genetic material is swept along with it. Included among the genes the scientists culled out as affected by positive selection were those related to the sense of smell and to the use of energy.

The researchers also learned that most of the protein-coding variations identified in their study were predicted to be harmful. Rare variation contributes not simply to each individual’s uniqueness, but also to the  risk for life-shortening illnesses.

What are the implications of these findings for understanding disease and advancing personalized medicine? Before answering, the researchers pointed to present limitations in robustly identifying functional important gene variation.

“Nevertheless,” they said, “there was considerable rare genetic variation among individuals that is predicted to be functional, which could explain variability in disease risk and in drug response.” The researchers would like more powerful tests to detect the effects of rare genetic variations on human health. They suggest that accounting gene-by-gene might improve research methods. They added that the population-specific nature of most of the single-letter code changes will make it challenging to replicate disease associations with a variant across the world’s people.

In addition to Akey and Bamshad, other researchers on the study were Jacob A. Tennessen, Timothy D. O’Connor, Wenqing Fu, Sean McGee, Mark J. Rieder, and Deborah A. Nickerson, all of the UW Department of Genome Sciences; Abigail W. Bigham of the UW Department of Pediatrics; Eimear E. Kenny, Simon Gravel and Carols D. Bustamante of Stanford University; Ron Do Stacey Gabriel, David Altshuler, and Shamil Sunyaev of the Broad Institute of MIT and Harvard University; Xiaoming Liu and Eric Boerwinkle , of the Texas Health Sciences Center in Houston; Goo Jun, Hyun Min Kang and Goncalo Abecasis of the University of Michigan; Daniel Jordan of the Division of Genetics at Brigham & Women’s Hospital in Boston; and Suzanne M. Leal of the Department of Molecular and Human Genetics at Baylor College of Medicine. The Center for Human Genetic Research at Massachusetts General Hospital and the Human Genome Sequencing Center at Baylor College of Medicine also contributed to this study.

For the past decade scientists have outlined new areas suitable for mammals likely to be displaced as climate change first makes their current habitat inhospitable, then unlivable. For the first time a new study considers whether mammals will actually be able to move to those new areas before they are overrun by climate change. Carrie Schloss, University of Washington research analyst in environmental and forest sciences, is lead author of the paper out online the week of May 14 in the Proceedings of the National Academy of Sciences.

"We underestimate the vulnerability of mammals to climate change when we look at projections of areas with suitable climate but we don't also include the ability of mammals to move, or disperse, to the new areas," Schloss said.

The percentage of mammal species unable to keep pace with climate change in the Americas range from zero and low (blue) to a high of nearly 40 percent (light orange).

U of Washington

Indeed, more than half of the species scientists have in the past projected could expand their ranges in the face of climate change will, instead, see their ranges contract because the animals won't be able to expand into new areas fast enough, said co-author Joshua Lawler, UW associate professor of environmental and forest sciences.

In particular, many of the hemisphere's species of primates – including tamarins, spider monkeys, marmosets and howler monkeys, some of which are already considered threatened or endangered – will be hard-pressed to outpace climate change, as are the group of species that includes shrews and moles. Winners of the climate change race are likely to come from carnivores like coyotes and wolves, the group that includes deer and caribou, and one that includes armadillos and anteaters.

The analysis looked at 493 mammals in the Western Hemisphere ranging from a moose that weighs 1,800 pounds to a shrew that weighs less than a dime. Only climate change was considered and not other factors that cause animals to disperse, such as competition from other species.

To determine how quickly species must move to new ranges to outpace climate change, UW researchers used previous work by Lawler that reveals areas with climates needed by each species, along with how fast climate change might occur based on 10 global climate models and a mid-high greenhouse gas emission scenario developed by the U.N. Intergovernmental Panel on Climate Change.

The UW researchers coupled how swiftly a species is able to disperse across the landscape with how often its members make such a move. In this case, the scientists assumed animals dispersed once a generation.

While bison cross this highway, they and other mammals may be less able to traverse or go around human-dominated landscapes, such as cities, found in the path the animals are taking to territory with climate that suits them.

C Schloss/U of Washington

It's understandable, for example, that a mouse might not get too far because of its size. But if there are many generations born each a year, then that mouse is on the move regularly compared to a mammal that stays several years with its parents in one place before being old enough to reproduce and strike out for new territory.

Western Hemisphere primates, for example, take several years before they are sexually mature. That contributes to their low-dispersal rate and is one reason they look especially vulnerable to climate change, Schloss said. Another reason is that the territory with suitable climate is expected to shrink and to reach the new areas animals in the tropics must generally go farther than in mountainous regions, where animals can more quickly move to a different elevation and a climate that suits them.

Those factors mean that nearly all the hemisphere's primates will experience severe reductions in their ranges, Schloss said, on average about 75 percent. At the same time species with high dispersal rates that face slower-paced climate change are expected to expand their ranges.

"Our figures are a fairly conservative – even optimistic – view of what could happen because our approach assumes that animals always go in the direction needed to avoid climate change and at the maximum rate possible for them," Lawler said.

The researchers were also conservative, he said, in taking into account human-made obstacles such as cities and crop lands that animals encounter. For the overall analysis they used a previously developed formula of "average human influence" that highlights regions where animals are likely to encounter intense human development. It doesn't take into account transit time if animals must go completely around human-dominated landscapes.

"I think it's important to point out that in the past when climates have changed – between glacial and interglacial periods when species ranges contracted and expanded – the landscape wasn't covered with agricultural fields, four-lane highways and parking lots, so species could move much more freely across the landscape," Lawler said.

Carrie Schloss

U of Washington

"Conservation planners could help some species keep pace with climate change by focusing on connectivity – on linking together areas that could serve as pathways to new territories, particularly where animals will encounter human-land development," Schloss said. "For species unable to keep pace, reducing non-climate-related stressors could help make populations more resilient, but ultimately reducing emissions, and therefore reducing the pace of climate change, may be the only certain method to make sure species are able to keep pace with climate change."

The third co-author of the paper is Tristan Nuñez, now at University of California, Berkeley. Both Schloss and Nuñez worked with Lawler while earning their master's degrees. Lawler did this work with support from the UW School of Environmental and Forest Sciences using, in part, models he previously developed with funding from the Nature Conservancy and the Cedar Tree Foundation.

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For more information:
Schloss, cell 440-666-6389, cschloss@uw.edu
Lawler, 206-685-4367, jlawler@u.washington.edu (Note: Lawler is away from the office the week of May 14 but will check for messages once or twice a day)

Drops of red and blue liquid move along the upper and lower surface of the vibrating UW platform at speeds up to 1 inch per second. This combined image shows drops as they move toward the center and merge.

Karl Bohringer, UW

"This allows us to move drops as far as we want, and in any kind of layout that we want," said Karl Böhringer, a UW professor of electrical engineering and bioengineering. The low-cost system, published in a recent issue of the journal Advanced Materials, would require very little energy and avoids possible contamination by diluting or electrifying the samples in order to move them.

The simple technology is a textured surface that tends to push drops along a given path. It's inspired by the lotus effect – a phenomenon in which a lotus leaf's almost fractal texture makes it appear to repel drops of water.

"The lotus leaf has a very rough surface, in which each big bump has a smaller bump on it," Böhringer said. "We can't make our surface exactly the same as a lotus leaf, but what we did is extract the essence of why it works."

A drop of liquid sits on the textured silicon surface that has arced rungs to guide the drop, and a grid of pillars to keep the drop in the channel.

Karl Bohringer, UW

Researchers used an audio speaker or machine to vibrate the platform at 50 to 80 times per second.  The asymmetrical surface moves individual drops along predetermined paths to mix, modify or measure their contents. Changing the vibration frequency can alter a drop's speed, or can target a drop of a certain size or weight.

"All you need is a vibration, and making these surfaces is very easy. You can make it out of a piece of plastic," Böhringer said. "I could imagine this as a device that costs less than a dollar – maybe much less than that – and is used with saliva or blood or water samples."

A close-up of the UW surface showing the arc edges and adjacent pillars.

Karl Bohringer, UW

The type of system is known as a "lab in a drop": all the ingredients are inside the drop, and surface tension acts as the container to keep everything together.

A student tried using a smartphone's speaker to vibrate the platform, but so far a phone does not supply enough energy to move the drops. To better accommodate low-energy audio waves, the group will use the UW's electron beam lithography machine to build a surface with posts up to 100 times smaller.

"There’s good evidence, from what we’ve done so far, that if we make everything smaller then we will need less energy to achieve the same effect," Böhringer said. "We envision a device that you plug into your phone, it’s powered by the battery of the phone, an app generates the right type of audio vibrations, and you run your experiment."

Co-authors of the paper are former UW undergraduate Todd Duncombe and former UW graduate student Yegȃn Erdem, both at the University of California, Berkeley; former UW postdoctoral researcher Ashutosh Shastry, now at Corium International in Menlo Park, Calif.; and Rajashree Baskaran, a UW affiliate assistant professor of electrical engineering who works at Intel Corp.

The research was funded by the National Science Foundation, the National Institutes of Health, Intel and the UW's Technology Gap Innovation Fund.

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For more information, contact Böhringer at 206-221-5177 or karl@ee.washington.edu.

The finding is important because it helps confirm that models that simulate global warming agree with observations, said Stephen Po-Chedley, a UW graduate student in atmospheric sciences who wrote the paper with Qiang Fu, a UW professor of atmospheric sciences.

They identified a problem with the satellite temperature record put together by the University of Alabama in Huntsville. Researchers there were the first to release such a record, in 1989, and it has often been cited by climate change skeptics to cast doubt on models that show the impact of greenhouse gases on global warming.

In their paper, appearing this month in the American Meteorological Society’s Journal of Atmospheric and Oceanic Technology, Po-Chedley and Fu examined the record from the researchers in Alabama along with satellite temperature records that were subsequently developed by the National Oceanic and Atmospheric Administration and Remote Sensing Systems.

The UW researchers are the first to come up with an adjustment for the way the Alabama scientists handled data from NOAA-9, a satellite that collected temperature data in the mid-1980s.

NOAA

Scientists like Po-Chedley and Fu have been studying the three records because each comes to a different conclusion.

“There’s been a debate for many, many years about the different results but we didn’t know which had a problem,” Fu said. “This discovery reduces uncertainty, which is very important.”

When they applied their correction to the Alabama-Huntsville climate record for a UW-derived tropospheric temperature measurement, it effectively eliminated differences with the other studies.

Scientists already had noticed that there were issues with the way the Alabama researchers handled data from NOAA-9, one satellite that collected temperature data for a short time in the mid-1980s. But Po-Chedley and Fu are the first to offer a calculation related to the NOAA-9 data for adjusting the Alabama findings, said Kevin Trenberth, a distinguished senior scientist at the National Center for Atmospheric Research.

“It should therefore make for a better record, as long as UAH accepts it,” he said.

To come up with the correction, Po-Chedley and Fu closely examined the way the three teams interpreted readings from NOAA-9 and compared it to data collected from weather balloons about the temperature of the troposphere.

They found that the Alabama research incorrectly factors in the changing temperature of the NOAA-9 satellite itself and devised a method to estimate the impact on the Alabama trend.

Like how a baker might use an oven thermometer to gauge the true temperature of an oven and then adjust the oven dial accordingly, the researchers must adjust the temperature data collected by the satellites.

That’s because the calibration of the instruments used to measure the Earth's temperature is different after the satellites are launched, and because the satellite readings are calibrated by the temperature of the satellite itself. The groups have each separately made their adjustments in part by comparing the satellite’s data to that of other satellites in service at the same time.

Once Po-Chedley and Fu apply the correction, the Alabama-Huntsville record shows 0.21 F warming per decade in the tropics since 1979, instead of its previous finding of 0.13 F warming. Surface measurements show the temperature of Earth in the tropics has increased by about 0.21 F per decade.

The Remote Sensing Systems and NOAA reports continue to reflect warming of the troposphere that’s close to the surface measurements, with warming of 0.26 F per decade and 0.33 F respectively.

The discrepancy among the records stems from challenges climate researchers face when using weather satellites to measure the temperature of the atmosphere. The records are a composite of over a dozen satellites launched since late 1978 that use microwaves to determine atmospheric temperature.

However, stitching together data collected by those satellites to discover how the climate has changed over time is a complicated matter. Other factors scientists must take into account include the satellite’s drift over time and differences in the instruments used to measure atmospheric temperature on board each satellite.

The temperature reports look largely at the troposphere, which stretches from the surface of the earth to around 10 miles above it, where most weather occurs. Climate models show that this region of the atmosphere will warm considerably due to greenhouse gas emissions. In fact, scientists expect that in some areas, such as over the tropics, the troposphere will warm faster than the surface of the Earth.

The paper does not resolve all the discrepancies among the records, and researchers will continue to look at ways to reconcile those conflicts.

“It will be interesting to see how these differences are resolved in the coming years,” Po-Chedley said.

The research was supported by the National Science Foundation and NOAA.

"So far, on average we're seeing about a 30 percent speedup in 10 years," said Twila Moon, a University of Washington doctoral student in Earth and space sciences and lead author of a paper documenting the observations published May 4 in Science.

These icebergs recently calved from the front of the north branch of Jakobshavn Isbrae, a large outlet glacier that drains 6.5 percent of the Greenland ice sheet. The fact that they are upright, indicated by their dirty and crevassed surfaces, suggests they calved from the floating end of a glacier.

Ian Joughin/UW

The faster the glaciers move, the more ice and meltwater they release into the ocean. In a previous study, scientists trying to understand the contribution of melting ice to rising sea level in a warming world considered a scenario in which the Greenland glaciers would double their velocity between 2000 and 2010 and then stabilize at the higher speed, and another scenario in which the speeds would increase tenfold and then stabilize.

At the lower rate, Greenland ice would contribute about four inches to rising sea level by 2100 and at the higher rate the contribution would be nearly 19 inches by the end of this century. But the researchers who conducted that study had little precise data available for how major ice regions, primarily in Greenland and Antarctica, were behaving in the face of climate change.

In the new study, the scientists created a decadelong record of changes in Greenland outlet glaciers by producing velocity maps using data from the Canadian Space Agency's Radarsat-1 satellite, Germany's TerraSar-X satellite and Japan's Advanced Land Observation Satellite. They started with the winter of 2000-01 and then repeated the process for each winter from 2005-06 through 2010-11, and found that the outlet glaciers had not increased in velocity as much as had been speculated.

"In some sense, this raises as many questions as it answers. It shows there's a lot of variability," said Ian Joughin, a glaciologist in the UW's Applied Physics Laboratory who is a coauthor of the Science paper and is Moon's doctoral adviser.

Other coauthors are Benjamin Smith of the UW Applied Physics Laboratory and Ian Howat, an assistant professor of earth sciences at Ohio State University. The research was funded by NASA and the National Science Foundation.

The scientists saw no clear indication in the new research that the glaciers will stop gaining speed during the rest of the century, and so by 2100 they could reach or exceed the scenario in which they contribute four inches to sea level rise.

"There's the caveat that this 10-year time series is too short to really understand long-term behavior," Howat said. "So there still may be future events – tipping points – that could cause large increases in glacier speed to continue. Or perhaps some of the big glaciers in the north of Greenland that haven't yet exhibited any changes may begin to speed up, which would greatly increase the rate of sea level rise."

The record showed a complex pattern of behavior. Nearly all of Greenland's largest glaciers that end on land move at top speeds of 30 to 325 feet a year, and their changes in speed are small because they are already moving slowly. Glaciers that terminate in fjord ice shelves move at 1,000 feet to a mile a year, but didn't gain speed appreciably during the decade.

In the east, southeast and northwest areas of Greenland, glaciers that end in the ocean can travel seven miles or more in a year. Their changes in speed varied (some even slowed), but on average the speeds increased by 28 percent in the northwest and 32 percent in the southeast during the decade.

"We can't look at one glacier for 100 years, but we can look at 200 glaciers for 10 years and get some idea of what they're doing," Joughin said.

Moon said she was drawn to the research from a desire to take the large store of data available from the satellites and put it into a usable form to understand what is happening to Greenland's ice.

"We don't have a really good handle on it and we need to have that if we're going to understand the effects of climate change," she said.

"We are going to need to continue to look at all of the ice sheet to see how it's changing, and we are going to need to continue to work on some tough details to understand how individual glaciers change."

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For more information, contact Moon at 406-600-2793 or twilap@uw.edu, or Joughin at 206-221-3177 or irj@uw.edu.

This means just a few towering white fir, sugar pine and incense cedars per acre at the Yosemite site are disproportionately responsible for photosynthesis, converting carbon dioxide into plant tissue and sequestering that carbon in the forest, sometimes for centuries, according to James Lutz, a University of Washington research scientist in environmental and forest sciences. He's lead author of a paper on the largest quantitative study yet of the importance of big trees in temperate forests being published online May 2 on PLoS ONE.

A handful of large-diameter trees per acre, such as these incense cedars, together with remains of big trees like the three-foot-wide white fir snag and downed debris account for half the forest biomass at a Yosemite National park study site.

J Lutz/U of Washington

"In a forest comprised of younger trees that are generally the same age, if you lose one percent of the trees, you lose one percent of the biomass," he said. "In a forest with large trees like the one we studied, if you lose one percent of the trees, you could lose half the biomass."

In 2009, scientists including Lutz reported that the density of large-diameter trees declined nearly 25 percent between the 1930s and 1990s in Yosemite National Park, even though the area was never logged. Scientists including co-author Andrew Larson of the University of Montana, also have found notable numbers of large trees dying in similar areas across the West.

Because of this, scientists have been keen to study a plot large enough to detect forest ecosystem changes involving large trees, including the effects of climate variability and change, possible culprits in the declines, Lutz said.

The new 63-acre study site in the western part of Yosemite National Park is one of the largest, fully-mapped plots in the world and the largest old-growth plot in North America. The tally of what's there, including the counting and tagging of 34,500 live trees, was done by citizen scientists, mainly undergraduate college students, led by Lutz,  Larson, Mark Swanson of Washington State University and James Freund of the UW.

Included was all above-ground biomass such as live trees, snags, downed woody debris, litter and what's called duff, the decaying plant matter on the ground under trees. Even when big trees die, they continue to dominate biomass in different ways. For example, 12 percent of standing snags were the remains of large-diameter trees, but still accounted for 60 percent of the total biomass of snags.

Live and dead biomass totaled 280 tons per acre (652 metric tons per hectare), a figure unmatched by any other forest in the Smithsonian Center for Tropical Forest Science network, a global network of 42 tropical and temperate forest plots including the one in Yosemite.

Washington State University's Mark Swanson pulls a tape tight around a 4-foot-wide sugar pine, one of the 34,500 live trees counted and tagged for long-term study in a Yosemite National Park study plot.

Washington State University

Trees in the western U.S. with trunks more than three feet across are typically at least 200 years old. Many forests that were heavily harvested in the 19^th and 20^th centuries, or those that are used as commercial forest lands today, don't generally have large-diameter trees, snags or large wood on the ground.

One implication of the research is that land managers may want to pay more attention to existing big trees, the co-authors said. Last year in the Yosemite National Park, for example, managers planning to set fires to clear out overgrown brush and densely packed small trees first used data from the study plot to figure out how many large trees to protect.

"Before the fires were started, crews raked around some of the large trees so debris wouldn't just sit and burn at the base of the tree and kill the cambium, the tissue under the bark that sustains trees," Lutz said.

In some younger forests that lack big trees, citizens and land managers might want to consider fostering the growth of a few big-trunked trees, Lutz said.

Another finding from the new work is that forest models based either on scaling theory or competition theory, which are useful for younger, more uniform forests, fail to capture how and where large trees occur in forests.

"These trees started growing in the Little Ice Age," Lutz said. "Current models can't fully capture the hundreds of years of dynamic processes that have shaped them during their lifetimes."

The research was funded by the Smithsonian Center for Tropical Forest Science.

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For more information:
Lutz, 206-616-3827, jlutz@uw.edu
Facebook page for Yosemite plot
http://www.facebook.com/pages/Yosemite-Forest-Dynamics-Plot/117620576445

Researchers at the University of Washington have studied vessel walls and found the cells pull more tightly together, reducing vascular leakage, in areas of fast-flowing blood. The finding could influence how doctors design drugs to treat high cholesterol, or how cardiac surgeons plan their procedures.

Their paper will be published in an upcoming issue of the American Journal of Physiology - Heart and Circulatory Physiology.

A layer of cells that coat the pulmonary artery grown on a bed of silicon microposts. After being exposed to a rapid flow, the cells make tighter junctions and tug more strongly on their neighbors.

Nathan Sniadecki, University of Washington

"Our results indicate that these cells can sense the kind of flow that they’re in, and structurally change how they hold themselves together," said lead author Nathan Sniadecki, a UW assistant professor of mechanical engineering. "This highlights the role that cellular forces play in the progression of cardiovascular disease."

It's known that the arteries carrying blood are leakier in areas of slow flow, promoting cholesterol buildup in those areas. But medical researchers believed this leakage was mostly biochemical – that cells would sense the slower flow and modify how proteins and enzymes function inside the cell to allow for more exchange.

The new results show that, like a group of schoolchildren huddling closer in a gust of wind, the cells also pull more tightly together when the blood is flowing past.

"The mechanical tugging force leads to a biochemical change that allows more and more proteins at the membrane to glue together," Sniadecki said. "We're still trying to understand what's happening here, and how mechanical tugging leads more proteins to localize and glue at the interface."

Sniadecki's group looks at the biomechanics of individual cells. For this experiment, they grew a patch of human endothelial cells, the thin layer of cells that line the inner walls of arteries and veins and act as a sort of nonstick coating for the vessels' walls. They grew the patch on an area about the width of a human hair, manufactured with 25 by 25 tiny flexible silicon posts.

A simulation of the posts that support the heart cells. Light blue is 1 nanometer of deflection, while dark red means the post is deflected by 2.5 nanometers.

Nathan Sniadecki, University of Washington

Knowing how cells respond to blood flow could help find new drugs to promote this tugging between cells. Better understanding of the interaction between blood flow and heart health could also guide surgeries.

"People could do simulations so a surgeon goes, ‘Ah, I should cut here versus over here, because that reconstruction will be a smoother vessel and will lead to fewer complications down the line, or as I put this stent in, put it here and make it more aerodynamic in design,'" Sniadecki said.

Co-authors are Lucas Ting, Joon Jung, Benjamin Shuman, Shirin Feghhi, Sangyoon Han, Marita Rodriguez in the UW's department of mechanical engineering, and Jessica Jahn at UW Medicine.

The research was funded by the National Institutes of Health, the National Science Foundation, the UW Medical Student Research Training Program and the UW Royalty Research Fund.

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For more information, contact Sniadecki at 206-685-6591 or nsniadec@uw.edu.

Pieces of plastic debris found in the oceans are smaller than many people think. Most are measured in millimeters.

Sea Education Association

After taking samples of water at a depth of 16 feet (5 meters), Proskurowski, a researcher at the University of Washington, discovered that wind was pushing the lightweight plastic particles below the surface. That meant that decades of research into how much plastic litters the ocean, conducted by skimming only the surface, may in some cases vastly underestimate the true amount of plastic debris in the oceans, Proskurowski said.

Reporting in Geophysical Research Letters this month, Proskurowski and co-lead author Tobias Kukulka, University of Delaware, said that data collected from just the surface of the water commonly underestimates the total amount of plastic in the water by an average factor of 2.5.

In high winds the volume of plastic could be underestimated by a factor of 27.

“That really puts a lot of error into the compilation of the data set,” Proskurowski said. The paper also detailed a new model that researchers and environmental groups can use to collect more accurate data in the future.

Plastic waste in the oceans is a concern because of the impact it might have on the environment. For instance, when fish ingest the plastics, it may degrade their liver functions. In addition, the particles make nice homes for bacteria and algae, which are then transported along with the particles into different regions of the ocean where they may be invasive and cause problems.

Giora Proskurowski deploys a net to collect samples that help estimate how much plastic debris is in the ocean.

Sea Education Association

Proskurowski gathered data on a 2010 North Atlantic expedition where he and his team collected samples at the surface, plus an additional three or four depths down as far as 100 feet.

“Almost every tow we did contained plastic regardless of the depth,” he said.

By combining the data with wind measurements, Proskurowski and his co-authors developed a simplified mathematical model that could potentially be used to match historical weather data, collected by satellite, with previous surface sampling to more accurately estimate the amount of plastic in the oceans.

In addition, armed with the new model, organizations and researchers in the future might monitor wind data and combine it with surface collections in order to better estimate how much plastic waste is in our oceans.

“By factoring in the wind, which is fundamentally important to the physical behavior, you’re increasing the rigor of the science and doing something that has a major impact on the data,” Proskurowski said.

The team plans to publish a “recipe” that simplifies the model so that a wide range of groups investigating ocean plastics, including those that aren’t oceanographers, can easily use the model. Following the recipe, which is available now by request, might encourage some consistency among the studies, he said.

“On this topic, what science needs to be geared toward is building confidence that scientists have solid numbers and that policy makers aren’t making judgments based on CNN reports,” he said. Descriptions of the so-called great Pacific garbage patch in widespread news reports may have led many people to imagine a giant, dense island of garbage while in fact the patch is made up of widely dispersed, millimeter-size pieces of debris, he said.

In the future, Proskurowski hopes to examine additional factors, including the drag of the plastics in water, complex ocean turbulence and wave height, that might improve the accuracy of the model. He also may have the chance to examine the relationship between wind speed and depth of plastic particles. The 2010 expedition had near-uniform wind conditions so the researchers were unable to test that relationship.

“This is a first pass,” he said.

Other co-authors of the paper are Kara Lavendar Law and Skye Morét-Ferguson, Sea Education Association, and Dylan Meyer, an undergraduate student from Eckerd College. Support for the project came from NOAA and the University of Delaware. The researchers relied on data collected by students participating in the Sea Education Association’s Plastics at SEA program.

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For more information:
Proskurowski, 206-685-3507, giora@uw.edu

Learn how a net is used to sample water at different depths below the sea surface, checking how the wind mixes floating plastic debris down into the water. Video credit: Sea Education Association

John Sahr with the passive radars on the roof of Sieg Hall. His group uses the radars to eavesdrop on FM radio stations in order to study the ionosphere.

Mary Levin, UW Photography

The past few months have seen a spate of solar flares – bringing spectacular views of the northern lights as far south as Seattle – along with media speculation that the electrical activity could disrupt power grids, satellites or ground airplanes.

John Sahr, a UW professor of electrical engineering who studies the upper atmosphere, is the regional go-to guy for such questions. We found some time in Sahr's busy schedule (he's also the UW's associate dean of undergraduate academic affairs and a part-time zombie hunter) to get his read on the space weather forecast.

Q: Can you describe what we've been seeing in the last few months?

Well, let's start with the sun. The sun has an 11-year cycle of times when it's more busy and less busy, more stormy and less stormy. For the past five years the sun has been pretty quiet. We're now rising up into the next solar maximum, which will last for about five years.

When the sun is stormy, there are more solar flares and more of what are called coronal mass ejections, which are basically just big puffs of electrically charged gas that burst out of the sun.

When this solar wind is gusty, it rattles the magnetic field around the Earth. That drives electric currents up and down along the Earth's magnetic field lines. When those currents run into the Earth's upper atmosphere, at altitudes of about 60 to maybe two- or three-hundred miles, they collide with the ionosphere and release energy in the form of light, causing the visual displays that we know of as the aurora.

The sky above Washington's Methow Valley on March 9, 2012.

Ed Stockard (MS '75), www.flickr.com/coastaleddy

The solar wind is a pretty good conductor, so it stretches the Earth's magnetic field downwind, and it wiggles and moves. To know what's happening during a solar storm, go over to the UW's Red Square and look at the flagpole. When there's a big stiff wind you hear it snapping and popping. That mechanical energy is the source, ultimately, for the northern lights. The Earth acts like a flagpole and the magnetosphere drapes past it, like the flag around the flagpole.

The lines of the Earth's magnetic field act like wires, and it's easy for the charged particles to move along the lines of the magnetic field. When people see the curtain effect of the aurora, what they're seeing is light emitted from currents that flow along the Earth's magnetic field. You actually can see the Earth's magnetic field with your eye.

Q: Can we see predict solar activity and northern lights?

We can, to some extent. If you look at the sun through a telescope, the part of the sun that's right in the center is roughly the part that's throwing gas at you. If there's a solar flare or sunspot that's more out toward the edge of the sun, we'll see that it happened, but the gas won't hit the Earth.

When there's a solar flare, the light gets here in eight minutes, but the coronal mass ejection gets here typically about two or two-and-a-half days later.

The other predictability has to do with the fact that the sun rotates every 30 days or so. So if you got hit with a bunch of solar wind from a particular sunspot, if the sunspot's still there when the sun has rotated around, there's a greater likelihood that we'll get a burst of solar wind a month later.

And then, finally, there's the 11-year cycle. We're not surprised that we're getting more magnetic storms now than we were for the past four or five years.

Q: Reporters often ask you to talk about solar activity. What do you think about the public's reaction to solar storms?

Well, it comes up that there's a solar storm, and sooner or later I'll get the phone calls. And there's always this hype about: "Whoa, it's a really big magnetic storm, and what's that gonna do?" And the answer is: "Well, people probably won't notice."

It used to be a more significant effect on the power grid, because the currents that flow in the upper atmosphere can disturb the power system by driving big currents through the transformers along transmission lines. But the power companies know how to modify their system so that it's much more robust to those great big surges.

Airlines that are flying over the poles will change their routes to be more southerly to reduce the energetic particle exposure, for the crews and passengers. By and large, we actually know how to respond to these things very well.

Probably the most significant impact of really big solar flares is the exposure of satellites. Satellites have to be designed with X-ray exposure in mind. One way is to have the satellites be within the Earth's magnetosphere, but there are some that manage to be outside the Earth's magnetosphere. One of the things that makes GPS a relatively reliable technology is that everybody wants it so badly, and there are now three or four different GPS-like systems. There's the U.S. GPS one, there's the Russian GLONASS, there's a European system. These systems work about the same, and they're constantly launching new satellites. They actually park spare satellites in orbit just to make sure the service keeps working. So I think [satellite] is something people can safely rely upon.

A little longer point of view, it's important to remember that when we have people in orbit, these magnetic storms are really providing extra energetic particles and more X-ray exposure. As we begin to think about doing things like traveling to Mars, one of the things for people to remember is that those spacecraft will probably have to travel during a sunspot minimum, just to keep the radiation exposure of the astronauts to a minimum.

Q: What can we expect to see over the next few months?

We expect the actual peak in the sunspot cycle to be somewhere between about a year and two years from now. So what we've been seeing for the past several days or weeks will be typical for the next three or four years. The prediction is that this sunspot cycle will actually be somewhat less intense than the last one, which peaked in 2000 and was very active all the way through 2004.

This particular sunspot cycle is interesting because the depth of the minimum was remarkably deep, and the time since the last solar max is closer to 14 years, so this has been a bit of an unusual solar cycle.

Q: Where do you recommend going in Seattle to see the northern lights?

The Northern Lights can happen any time of day, but of course you need a pretty dark sky to actually see them. What I always advise is anytime they fly across the nation at night, to get a window seat on the north side of the plane. I've seen great aurora that way.

You really just need a dark sky and a view to the north. I've seen them from my front porch. There's something called the k-p index, which is kind of the Richter scale for the upper atmosphere. If it's evening, and the k-p index is greater than 7, you should go look.

John Sahr and a former graduate student designed the radars, that work by eavesdropping on rock 'n roll radio broadcasts.

Mary Levin, UW Photography

Q: How are solar storms related to your research?

Solar storms generate a sonic boom, which is very loud sound waves in the plasma that scatter radio waves, at an altitude of about 60 miles. We can study this phenomenon directly with our radar. You can think of it as when the ionosphere is smooth, it's like a window that you can look through. But when it's been roughened up with sound waves, then it's like frosted glass, and so now you can actually see the glass instead of just looking through the glass.

Q: Why are you interested in studying sonic booms in the ionosphere?

One reason is that Mother Nature does it, so we study it. That's the most pure reason, I suppose.

Another reason is that the plasma physics of that part of the atmosphere are unusual. It's a relatively cold plasma, and it's a molecular plasma unlike plasmas that you find in the sun, which are atomic plasmas. It's surrounded by neutral gas, so there's a lot of chemistry that goes on.

It's also in a part of the sky that's very difficult to study because it's too high for balloons and aircraft, and too low for satellites. This is the part of the sky that ultimately burns up all the meteors, so instruments can't be there for very long. So remote sensing is the name of the game for getting long-term data for this part of the atmosphere.

Q: What instruments do you use to view the ionosphere?

The radar that the students and I operate was invented here at the UW in about 1997, by me and my former graduate student Frank Lind (PhD '01). The radar is the first of its kind, and it works extremely well. It's a very safe radar to be around, so it's good for educational purposes. We can teach students about radar and not have to worry about them being exposed to high-power radio waves.

I'm extremely grateful to the National Science Foundation for thinking it wasn't a crazy idea, and for funding it. Right now my student, Laura Vertatschitsch, is building a brand-new receiver that will work extremely well for digital TV as well as FM broadcasts.

Q: How does your radar work?

The thing that makes it novel is we don't have a transmitter. We listen to other people's broadcasts. In particular, we listen to commercial FM broadcasts.

Even more particularly, we prefer to listen to rock 'n' roll stations, which for interesting signal-processing reasons provide the best waveform for radar operation. Basically, they're noisy. Rock 'n' roll is much noisier than, say, classical music, which has quiet places, or for that matter talk radio, which has pauses.

We have receivers here on Sieg Hall, and then another set of receivers on the UW's Manastash Ridge Observatory, which is shielded from the Seattle transmitters by the Cascade Mountains. If there's any signal above the mountains it scatters back down to the receivers at the observatory near Ellensburg.

By comparing the data from the two places, we can see the echoes of turbulence in the ionosphere up to about 700 miles to the northeast. We can tell how far away the echoes are, how fast they're moving, and some of the spectral characteristics of the echoes that come back.

Q: What radio stations to you listen to?

Mostly we listen to 96.5 and 98.9. Several years ago I was interviewed by KUOW so we turned the radio to KUOW so my voice could be the transmitter signal. We didn't get anything, but it was fun to do.

Q: What does the increase in solar activity mean for your research?

It means we detect the turbulence we study more often, perhaps weekly, as opposed to yearly. In 2003 and 2004 we would see irregularities two or three times a week. But for the past several years it's been very, very scarce. So we're excited that we’re entering a new sunspot maximum.

Q: How did you first become interested in radio waves?

I became a radio amateur in junior high school. I picked up more physics and math and science and engineering along the way, but basically I turned my junior high-school hobby into my career.

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For more information, contact Sahr at 206-616-7175 or jdsahr@uw.edu.

Robert Winglee has spent years developing a magnetized ion plasma system to propel a spacecraft at ultra-high speeds, making it possible to travel to Mars and return to Earth in as little time as 90 days. The problem is that cost and other issues have dampened the desire to send astronauts to Mars or any other planet.

In this artist’s conception, a magnetized beam of ionized plasma is applied to a spacecraft headed on an interplanetary journey. The same technology could be used to remove dead satellites and other debris from Earth orbit.

University of Washington

But Winglee, who heads the University of Washington’s Earth and Space Sciences Department, believes his problem might actually be a solution to the problem of space junk crowding the orbital paths around Earth.

A magnetized-beam plasma propulsion device (mag-beam for short) in Earth orbit would be able to use a focused ion stream to push dead satellites and other debris toward Earth’s atmosphere, where they would mostly burn up on re-entry. The idea has drawn interest, and some funding, from the U.S. Defense Department.

“Our proposal was that we could mitigate a whole region of space rather than work with individual pieces one at a time,” Winglee said.

As a propulsion method, mag-beam would interact with a specialized receptor on a spacecraft, pushing it to speeds perhaps greater than 18,000 miles per hour. Satellites orbiting Earth don’t have those specialized receptors, but Winglee said applying the beam directly to the satellite would still provide enough momentum to move a satellite toward the atmosphere.

A geosynchronous orbit, one in which a satellite returns to the same position above the Earth each day, “is very valuable space, but it’s full of dead satellites,” he said. For decades, communications satellites have been placed in orbits from hundreds of miles to several thousand miles above sea level to create a fixed point in the sky for ground installations to communicate with satellites. Many of those satellites have ceased to function, though they continue in their orbits.

That might not sound like such a big problem, but as space gets more crowded with gadgets, the chance of a collision between two satellites becomes even greater. Then, instead of two larger objects to worry about, satellites worth vast sums of money – and perhaps even space vehicles such as the International Space Station – would have to navigate through a cloud of debris. Even a tiny washer or screw traveling at 6,700 miles per hour in Earth orbit could cause serious damage to another object.

Using a mag-beam to clean up the debris is feasible now, Winglee said, and could be accomplished through a standard satellite mission costing perhaps $300 million.

The technology would not be useful for pushing near-Earth asteroids or comets away from the planet, he said, because they have too much mass for the mag-beam to be effective.

Meanwhile, Winglee and his students continue research in his Johnson Hall laboratory on the possibility of placing mag-beam units in orbit around Earth and around a planet such as Mars that humans might want to explore. With a unit on each end – one to give a spacecraft a high-velocity push on its journey and the other to slow it at its destination – a mission to Mars could be accomplished in as little as 90 days, rather than the 2.5 years it would take with conventional means.

“We’re continuing on a shoestring budget, and we’re modeling what the system can do over longer distances,” Winglee said.

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Consider whether comic books can make you healthier. Watch water run uphill. Discover what happens when you combine computers, floating objects and quantum physics.

Interested? Then grab the kids and head for Paws-On Science: Husky Weekend, March 30, 31 and April 1, at Pacific Science Center, for these activities and a chance to visit 45 other stations featuring UW research.

UW faculty, staff, students and their families receive a 20 percent discount on admission during the event, as do UW alums.

Paws-On Science, now in its third year, is a collaboration of Pacific Science Center and the University of Washington's Office of External Affairs.

Hours are 10 a.m.-5 p.m. Friday and 10 a.m.-6 p.m. Saturday and Sunday.

Paws-On Science participant.

For fun, the following are also scheduled:

• Friday, Harry the Husky, 10-11 a.m.
• Saturday, Husky marching band and cheer team, 12-1 p.m.; Husky mascot DUBS and Harry the Husky, 1-2 p.m.
• Sunday, Harry the Husky, 1-2 p.m.