CU research: Microchips using light instead of wires boosts speed exponentially
Sep 30th
CU, MIT breakthrough in photonics
could allow for faster and faster electronics
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.
-CU-
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Playing inspired volleyball, Buffs whip No.11 UCLA
Sep 28th
The win snapped a 41-match losing streak to ranked opponents
BOULDER— The University of Colorado played inspiring volleyball on Friday night to defeat No. 11 UCLA in front of a crowd of almost 2,800 at the Coors Events Center 3-1 (27-29, 25-15, 24-26, 25-23, 15-12).
The win is the first ever for the Buffs against the Bruins and it’s also just the third time CU has ever taken a set or more against UCLA. CU improved to 9-2 (1-1 Pac-12) with the win, while UCLA fell to 9-3 (0-2 Pac-12).
“This is the most exciting night I have been a part of here, not just because of the victory, but because of the effort on the court and what the administration did [as far as marketing goes] to pack this place,” coach Liz Kritza said. “It was really a significant night for our program to be able to take out the No. 11-ranked team in the country in front of a crowd like this on our home court. It’s a milestone for our program. Excitement doesn’t do it justice.”
This was the first win for the Buffs over a ranked team since 2008 when they defeated No. 2 Nebraska in four sets (25-19, 27-25, 18-25, 25-16), snapping a 41-match losing streak to ranked opponents.
“I couldn’t be more proud about how we came back tonight,” Kritza said. “I like that these kids have guts, they’re fearless, and most importantly that they play different roles even when I am subbing people in and out. They all get the focuses and the purposes, that’s why we are able to do that, because we are a good team.”
Junior Taylor Simpson had a team-leading 15 kills
“It’s so exciting to be a part of something bigger than yourself,” junior outside hitter Taylor Simpson said about the win. “It’s so awesome that I can’t put it in words. I can’t wait to see what we do with the rest of the season.”
Simpson led the Buffs with 15 kills and both Nikki Lindow and Neira Ortiz Ruiz hammered 14 kills each. Lindow had a monster game as she also added a career-high 12 blocks, which tied the fourth best in CU history and hit a team-high .464 with just one error on 28 swings.
Kelsey English and Kerra Schroeder each had eight kills in the victory. English had three block assists and Schroeder helped defensively with 11 digs. Simpson also earned her fifth double-double this season with 15 digs and added six blocks. Nicole Edelman handed out a career-best 56 assists and added four kills and 12 digs. Cierra Simpson also came up with 15 digs in the victory.
As a team, the Buffs recorded 69 kills and hit .211 while UCLA had 66 kills and hit .169. The Buffs also out-blocked UCLA 17.0-12.0 and had the slight edge in digs (72-71).
“What’s even better is that we showed some serious teamwork tonight.” Lindow said. “It was the most calm feeling I have ever had on the court. We had confidence in our eyes and no question on how to handle this game even in the fourth set. It was the greatest feeling I have ever felt while being a part of this team.”
The Bruins had two players with 18 kills each, Mariana Aquino and Karsta Lowe. Karly Drolson led the Bruins with a career-high 23 digs and Zoe Nightingale recorded a team-high nine blocks.
Colorado played a very close set with the Bruins despite falling behind 12-6 to start the game. CU came back to tie the score at 20-20 and from that point, it was a back and forth battle to the end. The Buffs fought off four UCLA set points before the Bruins were able to put together two straight points to take the frame 29-27. CU had 19 kills in the set and hit .233 while UCLA recorded 14 kills and hit .286.
The Buffs used the momentum they gained from the end of the first set and pounced on UCLA, taking a 9-6 lead in the second set. The Buffs were hot and continued to add to their lead, going up 20-12. The Bruins didn’t have an answer and CU easily finished the set 25-15. The Buffs hit .233 in the set and held the Bruins to -.024.
UCLA took the advantage to start the third set (7-3), but the Buffs rallied back to even the score with a 4-0 run (7-7). The Buffs took their first lead of the set at 11-10 with a kill from Ortiz Ruiz and added to their lead with a 6-2 run to take a 17-12 advantage. UCLA got back within two points at 19-17 and tied the score two points later.
After a CU timeout, the Bruins took the lead back with a kill (20-19), but Taylor Simpson answered for the Buffs with her own kill (20-20). The score was tied again at 21-21 before UCLA went up 24-22. CU fought off two set points with kills from Lindow and Taylor Simpson to tie the set again (24-24). This time the Bruins used a timeout and took the first two points out of the break to win the set 26-24.
UCLA got out to a 12-2 lead in the fourth set. CU started to come back slowly and forced the Bruins to take a timeout at 12-6 after four straight points. After the break, the Buffs added three straight points to bring the score to 12-9 and completed the comeback by tying the score at 15-15. CU went ahead for the first time in the set at 18-17 after a huge block from English and Taylor Simpson. The Buffs took a two-point lead at 22-20 to force UCLA to call its final timeout of the set, after which CU would go up 24-21 on the Bruins. UCLA fought off the first two set points (24-23), which made CU spend a timeout. Out of the break, Ortiz Ruiz finished the set with a kill (25-23).
The fifth set was another battle for the two teams. CU took an 8-7 lead at the side-change and went up 9-7. After a quick UCLA break, the Buffs added to their lead, going up 11-8. The Bruins weren’t just going to go away and snatched the following two points, forcing CU to take a timeout. Lindow hammered a kill to give the Buffs a two-point cushion (12-10). UCLA took the following point, but the Buffs didn’t get discouraged and were able to finish the set and the match 15-12. CU hit .625 in the final set with 10 kills and no errors on 16 attacks.
“I do want to say thank you to State Farm, they sponsored this match,” Kritza said. “It was a significant contribution. It was a great atmosphere for our players. They got a bunch of tickets out to the community. It’s one of the best matches I have seen here for volleyball in the Coors Event Center. Thanks to the fans and to State Farm. I also have to give kudos to my assistant coaches for preparing this team and making good adjustments when needed.”
The Buffs will be back in action on Tuesday, October 1 with a contest against Wyoming in Laramie, Wyo. at 5 p.m.
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CU study; Death of microbes could determine time of death
Sep 27th
An intriguing study led by the University of Colorado Boulder may provide a powerful new tool in the quiver of forensic scientists attempting to determine the time of death in cases involving human corpses: a microbial clock.
The clock is essentially the lock-step succession of bacterial changes that occur postmortem as bodies move through the decay process. And while the researchers used mice for the new study, previous studies on the human microbiome – the estimated 100 trillion or so microbes that live on and in each of us – indicate there is good reason to believe similar microbial clocks are ticking away on human corpses, said Jessica Metcalf, a CU-Boulder postdoctoral researcher and first author on the study.
“While establishing time of death is a crucial piece of information for investigators in cases that involve bodies, existing techniques are not always reliable,” said Metcalf of CU-Boulder’s BioFrontiers Institute. “Our results provide a detailed understanding of the bacterial changes that occur as mouse corpses decompose, and we believe this method has the potential to be a complementary forensic tool for estimating time of death.”
Dead and dying microbes could determine time of death for forensics pathologists
Currently, investigators use tools ranging from the timing of last text messages and corpse temperatures to insect infestations on bodies and “grave soil” analyses, with varying results, she said. And the more days that elapse following a person’s demise, the more difficult it becomes to determine the time of death with any significant accuracy.
Using high-technology gene sequencing techniques on both bacteria and microbial eukaryotic organisms like fungi, nematodes and amoeba postmortem, the researchers were able to pinpoint time of mouse death after a 48-day period to within roughly four days. The results were even more accurate following an analysis at 34 days, correctly estimating the time of death within about three days, said Metcalf.
A paper on the subject was published Sept. 23 in the new online science and biomedical journal, eLIFE, a joint initiative of the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust Fund. The study was funded by the National Institutes of Justice.
The researchers tracked microbial changes on the heads, torsos, body cavities and associated grave soil of 40 mice at eight different time points over the 48-day study. The stages after death include the “fresh” stage before decomposition, followed by “active decay” that includes bloating and subsequent body cavity rupture, followed by “advanced decay,” said Chaminade University forensic scientist David Carter, a co-author on the study.
“At each time point that we sampled, we saw similar microbiome patterns on the individual mice and similar biochemical changes in the grave soil,” said Laura Parfrey, a former CU-Boulder postdoctoral fellow and now a faculty member at the University of British Columbia who is a microbial and eukaryotic expert. “And although there were dramatic changes in the abundance and distribution of bacteria over the course of the study, we saw a surprising amount of consistency between individual mice microbes between the time points — something we were hoping for.”
As part of the project, the researchers also charted “blooms” of a common soil-dwelling nematode well known for consuming bacterial biomass that occurred at roughly the same time on individual mice during the decay period. “The nematodes seem to be responding to increases in bacterial biomass during the early decomposition process, an interesting finding from a community ecology standpoint,” said Metcalf.
“This work shows that your microbiome is not just important while you’re alive,” said CU-Boulder Associate Professor Rob Knight, the corresponding study author who runs the lab where the experiments took place. “It might also be important after you’re dead.”
The research team is working closely with assistant professors Sibyl Bucheli and Aaron Linne of Sam Houston State University in Huntsville, Texas, home of the Southeast Texas Applied Forensic Science Facility, an outdoor human decomposition facility known popularly as a “body farm.” The researchers are testing bacterial signatures of human cadavers over time to learn more about the process of human decomposition and how it is influenced by weather, seasons, animal scavenging and insect infestations.
The new study is one of more than a dozen papers authored or co-authored by CU-Boulder researchers published in the past several years on human microbiomes. One of the studies, led by Professor Noah Fierer, a co-author on the new study, brought to light another potential forensic tool — microbial signatures left on computer keys and computer mice, an idea enthralling enough it was featured on a “CSI: Crime Scene Investigation” television episode.
“This study establishes that a body’s collection of microbial genomes provides a store of information about its history,” said Knight, also an associate professor of chemistry and biochemistry and a Howard Hughes Medical Institute Early Career Scientist. “Future studies will let us understand how much of this information, both about events before death — like diet, lifestyle and travel — and after death can be recovered.”
In addition to Metcalf, Fierer, Knight, Carter and Parfrey, other study authors included Antonio Gonzalez, Gail Ackerman, Greg Humphrey, Mathew Gebert, Will Van Treuren, Donna Berg Lyons and Kyle Keepers from CU-Boulder, former BioFrontiers doctoral student Dan Knights from the University of Minnesota, and Yan Go and James Bullard from Pacific Biosciences in Menlo Park, Calif. Keepers participated in the study as an undergraduate while Gonzalez, now a postdoctoral researcher, was a graduate student during the study.
“There is no single forensic tool that is useful in all scenarios, as all have some degree of uncertainty,” said Metcalf. “But given our results and our experience with microbiomes, there is reason to believe we can get past some of this uncertainty and look toward this technique as a complementary method to better estimate time of death in humans.”
Gene sequencing equipment for the study included machines from Illumina of San Diego and Pacific Biosciences of Menlo Park, Calif. The Illumina data were generated at CU-Boulder in the BioFrontiers Next Generation Sequencing Facility.
To access a copy of the paper visit http://dx.doi.org/10.7554/eLife.01104. For more information on the BioFrontiers Institute visit http://biofrontiers.colorado.edu.
-CU-
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