Tech & Science
Technology and Science news from Boulder, Colorado
CU researchers find hyper evolution in walking stick insects
Oct 21st
off a cascade of ecological impacts,
new CU-Boulder study finds
A California walking stick insect that has evolved to produce individuals with two distinct appearances—an all-green form that camouflages well with broader leaves and a form with a white stripe running down its back that blends better with needle-like leaves—can markedly affect its broader ecological community when the appearance of the bug is mismatched with the plant it’s living on.
The new findings, based on research carried out at the University of Colorado Boulder, illustrate the ability of rapid evolution to cause a cascade of ecological impacts.
The scientists found that a walking stick insect that is not well camouflaged is more likely to be eaten by birds, and in turn, those birds are then also more likely to feast on the spiders, caterpillars, plant hoppers, ants and other arthropods living on the same plant. The resulting overall reduction in bugs living on the plant also means that the plant itself was less likely to be attacked by sap-feeding insects.
“Our study shows that the evolution of poor camouflage in one species can affect all the other species living there and affect the plant as well,” said Tim Farkas, lead author of the study published in the journal Current Biology. “It’s intuitive, but also really surprising.”
Farkas led the study as an ecology and evolutionary biology doctoral student in Assistant Professor Patrik Nosil’s lab at CU-Boulder. Nosil and CU-Boulder doctoral student Aaron Comeault are also study co-authors. All three have since moved to the University of Sheffield in England.
Evolution is often thought of as a process that unfolds slowly over centuries if not millennia, as individuals with genetic advantages have a greater chance of surviving to pass down their genes to the next generation.
But scientists are increasingly identifying instances when evolution works on a much shorter time scale. An oft-cited example of rapid evolution is the peppered moth. The light-colored moths were historically able to camouflage themselves against lichen-covered tree bark in England. A darker variant of the moth existed but was more rare, since birds were able to easily spot the dark moth against the light trees. But during the industrial revolution, when soot blackened the trees, natural selection favored a darker variation of the moth, which began to flourish while the light-colored variant became less common.
Evolution on such a rapid scale opens up the possibility that the process could have ecological effects in the short term, impacting population sizes or changing the community makeup, for example.
Researchers have begun to compile examples of these “eco-evolutionary dynamics.” The new study offers some of the most comprehensive evidence yet that evolution can drive ecological change.
“We have combined both experimental and observational data with mathematical modeling to show that evolution causes ecological effects and that it does so under natural conditions,” Farkas said. “We also focused simultaneously on multiple evolutionary processes—including natural selection and gene flow—rather than just one, which affords us some unique insights.”
Farkas and his colleagues—including Ilkka Hanski and Tommi Mononen, both of the University of Helsinki in Finland—focused their attention on the walking stick Timema cristinae, which lives in Southern California. The flightless insect lives primarily on two shrubs: chamise, which has narrow, needle-like leaves; and greenbark ceanothus, which has broad, oval-shaped leaves. The variant of the walking sticks that have a white stripe down their backs are better camouflaged on the chamise, while the solid-green walking sticks are better camouflaged on the greenbark ceanothus.
The research team began by cataloguing the walking sticks living on the two types of shrubs in 186 research patches, and determined that the striped walking sticks were indeed more common on chamise and vice versa.
In a second experiment, the researchers artificially stocked the needle-like chamise with the different variants of walking sticks. A month later, they sampled the shrubs and found that more striped walking sticks survived than un-striped walking sticks. They also found that chamise stocked with striped walking sticks were home to a greater number of arthropods as well as a greater variety of arthropods than shrubs stocked with un-striped walking sticks. Finally, there were more leaves damaged by hungry insects on chamise stocked with striped walking sticks.
The scientists surmised that the differences were caused by scrub jays and other birds that feed on walking sticks. A group of easy-to-spot walking sticks could attract birds, which might then feed on other arthropods as well. To test their idea, the researchers repeated the experiment, but in this case, they caged some of the shrubs to keep the birds from feeding. As they expected, the caged chamise stocked with un-striped walking sticks did not have the same drop in numbers as they did when the bushes were not caged.
“Studies of how rapid evolution can affect the ecology of populations, communities and ecosystems are difficult to accomplish and therefore rare,” Farkas said. “We’re hoping our research helps biologists to appreciate the extent of dynamic interplay between ecology and evolution, and that it can be used by applied scientists to combat emerging threats to biodiversity, ecosystem services, and food security.”
Funding for the study was provided by CU-Boulder, the European Research Council and the Academy of Finland.
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Boulder High, CU grad astronaut Scott Carpenter dies at 88
Oct 11th
Carpenter, a Boulder native, entered CU-Boulder’s astronautical engineering program in 1945, eventually earning a bachelor of science degree. He orbited Earth three times on May 24, 1962, in NASA’s Aurora 7 capsule before splashing down in the Atlantic Ocean.
Carpenter was the first of 18 CU-Boulder astronaut affiliates to have flown in space. As one of the first NASA astronauts, Carpenter and his colleagues were celebrated in the Tom Wolfe book, “The Right Stuff,” which told the story of early military test pilots and the original Mercury 7 astronauts.
Born in Boulder on May 1, 1925, Carpenter and graduated from Boulder High School in 1943. He then entered the Navy’s V12a flight training program at Colorado College in Colorado Springs. He spent the next year training in California and Iowa, returning to Boulder in 1945 to study at CU-Boulder.
“In his two-decades long career as a Naval aviator, astronaut and aquanaut, Scott Carpenter brought honor and distinction to CU-Boulder while embodying the adventurous spirit of our nation,” said CU-Boulder Chancellor Philip P. DiStefano. “Our space program, and all space and ocean researchers everywhere, owe him a debt of gratitude. He will be sorely missed.”
In 1965 Carpenter took a leave of absence from NASA to participate in the Navy’s Man-in-the Sea Project as an aquanaut in the SEALAB II project off the coast of La Jolla, Calif. where he spent 30 days living and working on the ocean floor at a depth of more than 200 feet. Because of his groundbreaking deep-sea diving experiences with the Navy, Carpenter is hailed by many to be the first person to conquer both outer and inner space.
“My colleagues and I are deeply saddened by the passing of Astronaut Scott Carpenter,” said CU-Boulder aerospace engineering sciences Chair Penina Axelrad. “He has long been a member of the CU family and a tremendous inspiration for our aerospace faculty and students.”
In a 2012 interview with CU’s alumni magazine, the Coloradan, Carpenter spoke about his historic space journey. “I still remember what a thrill it was being up there — I liked the feeling of weightlessness, and the view I had of Earth.”
Carpenter and the other Mercury 7 astronauts created the Astronaut Scholarship Foundation in 1984. The foundation now involves more than 80 astronauts, awards 28 $10,000 scholarships annually and has dispersed more than $3 million to promising students in science and engineering since 1986.
As one of the original Mercury 7 astronauts, Carpenter followed Alan Shepard, Gus Grissom and Glenn into space and was followed by Wally Schirra, Gordon Cooper and Deke Slayton.
Carpenter was commissioned in the U.S. Navy in 1949 and flew a variety of missions during the Korean War. He attended Navy Test Pilot School in Maryland in 1954 and was assigned as an Air Intelligence Officer on the USS Hornet aircraft carrier. In April of 1959 he was selected by NASA to be an astronaut.
Although he was one course requirement short of graduating with a bachelor’s degree in aeronautical engineering when he left CU in 1949, the university awarded him his degree in 1962 following the successful Aurora 7 flight. When presenting the degree to Carpenter, then-CU President Quigg Newton noted that “his subsequent training as an astronaut has more than made up for his deficiency in the subject of heat transfer.”
In 1967 he became the Navy’s director of aquanaut operations during the SEALAB III experiment. After retiring from the Navy in 1969, he founded and became CEO of Sea Sciences Inc., a venture capital corporation that developed programs aimed at enhanced use of ocean resources and improved health of the planet. He worked closely with noted diver and scientist Jacques Cousteau and members of his Calypso team, and subsequently dove in most of the world’s oceans, including under Arctic ice.
Carpenter later became a consultant to industry and the private sector and has lectured around the world, narrated TV documentaries and written several books, including the 2002 New York Times best-seller, “For Spacious Skies: The Uncommon Journey of a Mercury Astronaut” co-authored with his daughter, Kris Stoever.
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CU research: Microchips using light instead of wires boosts speed exponentially
Sep 30th
could allow for faster and faster electronics
A pair of breakthroughs in the field of silicon photonics by researchers at the University of Colorado Boulder, the Massachusetts Institute of Technology and Micron Technology Inc. could allow for the trajectory of exponential improvement in microprocessors that began nearly half a century ago—known as Moore’s Law—to continue well into the future, allowing for increasingly faster electronics, from supercomputers to laptops to smartphones.
The research team, led by CU-Boulder researcher Milos Popovic, an assistant professor of electrical, computer and energy engineering, developed a new technique that allows microprocessors to use light, instead of electrical wires, to communicate with transistors on a single chip, a system that could lead to extremely energy-efficient computing and a continued skyrocketing of computing speed into the future.
Popovic and his colleagues created two different optical modulators—structures that detect electrical signals and translate them into optical waves—that can be fabricated within the same processes already used in industry to create today’s state-of-the-art electronic microprocessors. The modulators are described in a recent issue of the journal Optics Letters.
First laid out in 1965, Moore’s Law predicted that the size of the transistors used in microprocessors could be shrunk by half about every two years for the same production cost, allowing twice as many transistors to be placed on the same-sized silicon chip. The net effect would be a doubling of computing speed every couple of years.
The projection has held true until relatively recently. While transistors continue to get smaller, halving their size today no longer leads to a doubling of computing speed. That’s because the limiting factor in microelectronics is now the power that’s needed to keep the microprocessors running. The vast amount of electricity required to flip on and off tiny, densely packed transistors causes excessive heat buildup.
“The transistors will keep shrinking and they’ll be able to continue giving you more and more computing performance,” Popovic said. “But in order to be able to actually take advantage of that you need to enable energy-efficient communication links.”
Microelectronics also are limited by the fact that placing electrical wires that carry data too closely together can result in “cross talk” between the wires.
In the last half-dozen years, microprocessor manufacturers, such as Intel, have been able to continue increasing computing speed by packing more than one microprocessor into a single chip to create multiple “cores.” But that technique is limited by the amount of communication that then becomes necessary between the microprocessors, which also requires hefty electricity consumption.
Using light waves instead of electrical wires for microprocessor communication functions could eliminate the limitations now faced by conventional microprocessors and extend Moore’s Law into the future, Popovic said.
Optical communication circuits, known as photonics, have two main advantages over communication that relies on conventional wires: Using light has the potential to be brutally energy efficient, and a single fiber-optic strand can carry a thousand different wavelengths of light at the same time, allowing for multiple communications to be carried simultaneously in a small space and eliminating cross talk.
Optical communication is already the foundation of the Internet and the majority of phone lines. But to make optical communication an economically viable option for microprocessors, the photonics technology has to be fabricated in the same foundries that are being used to create the microprocessors. Photonics have to be integrated side-by-side with the electronics in order to get buy-in from the microprocessor industry, Popovic said.
“In order to convince the semiconductor industry to incorporate photonics into microelectronics you need to make it so that the billions of dollars of existing infrastructure does not need to be wiped out and redone,” Popovic said.
Last year, Popovic collaborated with scientists at MIT to show, for the first time, that such integration is possible. “We are building photonics inside the exact same process that they build microelectronics in,” Popovic said. “We use this fabrication process and instead of making just electrical circuits, we make photonics next to the electrical circuits so they can talk to each other.”
In two papers published last month in Optics Letters with CU-Boulder postdoctoral researcher Jeffrey Shainline as lead author, the research team refined their original photonic-electronic chip further, detailing how the crucial optical modulator, which encodes data on streams of light, could be improved to become more energy efficient. That optical modulator is compatible with a manufacturing process—known as Silicon-on-Insulator Complementary Metal-Oxide-Semiconductor, or SOI CMOS—used to create state-of-the-art multicore microprocessors such as the IBM Power7 and Cell, which is used in the Sony PlayStation 3.
The researchers also detailed a second type of optical modulator that could be used in a different chip-manufacturing process, called bulk CMOS, which is used to make memory chips and the majority of the world’s high-end microprocessors.
Vladimir Stojanovic, who leads one of the MIT teams collaborating on the project and who is the lead principal investigator for the overall research program, said the group’s work on optical modulators is a significant step forward.
“On top of the energy-efficiency and bandwidth-density advantages of silicon-photonics over electrical wires, photonics integrated into CMOS processes with no process changes provides enormous cost-benefits and advantage over traditional photonic systems,” Stojanovic said.
The CU-led effort is a part of a larger project on building a complete photonic processor-memory system, which includes research teams from MIT led by Stojanovic, Rajeev Ram and Michael Watts, a team from Micron Technology led by Roy Meade and a team from the University of California, Berkeley, led by Krste Asanovic. The research was funded by the Defense Advanced Research Projects Agency and the National Science Foundation.
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