Intel to Mass-Produce New 3-D Transistors for Faster, More Efficient Computer Chips

3-D Transistor This image shows the vertical fins of Intel’s 22 nanometer microprocessor using 3-D Tri-Gate transistors. Intel
In a move that could remake the microchip industry, Intel announced Wednesday it will start mass-producing the first three-dimensional silicon transistors. The 3-D transistor design, which Intel says will improve efficiency by more than one-third, will be integrated into a 22-nanometer node in an Intel chip called Ivy Bridge.
It’s a major change from the two-dimensional flat transistor structure we all know and love, which has powered every computer chip for the last 50 years. The 3-D switch design and the scale of its production will allow Moore’s Law to advance apace, Intel said.
Moore’s Law holds that the number of transistors that can be placed on a circuit will double every two years, but this places limits on the circuits’ size — a growing problem as engineers cram greater numbers of transistors onto ever-tinier chips. A 3-D switch could allow computer chips to be built like skyscrapers, optimizing space by building upward, and thereby allowing uninhibited transistor growth.
The Tri-Gate transistors consist of a thin 3-D silicon fin that arises vertically from the silicon substrate, Intel explains. Each fin has three gates, one on the top and one on each side, which allows for greater transistor current control. When it’s on, current flow is more efficient, and when the switches are off, the flow of electrons is closer to zero. By contrast, flat transistors have one gate, only on top.
All this leads to greater efficiency, allowing chips to operate at a lower voltage and with lower leakage — Intel claims a whopping 37 percent performance increase over its 2-D chips. Since the fins and their gates are vertical, more transistors can be packed close together. Eventually, designers will be able to make taller fins, aiming for even better performance.
“It will give product designers the flexibility to make current devices smarter and wholly new ones possible,” said Mark Bohr, a senior fellow at Intel.
More than 6 million 22-nm Tri-Gate transistors could fit inside the period at the end of this sentence, according to the company. (If you zoom in, who knows how many could fit!)
The new transistors will be integrated into Ivy Bridge-based Intel Core processors by the end of this year, which consumers will be able to get in 2012, Intel said.
Plenty of other chip designers have been talking about 3-D chips — just last month, we saw a 2-D reprogrammable one designed to behave as if it was a 3-D one. But Intel has taken it a step further by figuring out how to mass-produce them.
It’s technically 3-D because the switches are vertical and horizontal, but the transistors are not stacked, allowing electrons to flow in three dimensions — that’s a holy Grail of microprocessor design. But a new circuit design that allows more transistors on tinier spaces certainly sounds like a major breakthrough.
[IBM via PC Magazine]

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Particles appear to travel faster than light: OPERA experiment reports anomaly in flight time of neutrinos

ScienceDaily (Sep. 23, 2011) — Scientists with the OPERA experiment, which observes a neutrino beam from CERN 730 km away at Italy's INFN Gran Sasso Laboratory, are presenting surprising new results (in a seminar at CERN on Sept. 23, 2011) that appear to show neutrinos traveling faster than light.

The OPERA result is based on the observation of over 15000 neutrino events measured at Gran Sasso, and appears to indicate that the neutrinos travel at a velocity 20 parts per million above the speed of light, nature's cosmic speed limit. Given the potential far-reaching consequences of such a result, independent measurements are needed before the effect can either be refuted or firmly established. This is why the OPERA collaboration has decided to open the result to broader scrutiny. The collaboration's result is available on the preprint server arXiv (http://arxiv.org/list/hep-ex/new).

"This result comes as a complete surprise," said OPERA spokesperson, Antonio Ereditato of the University of Bern. "After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation."

"When an experiment finds an apparently unbelievable result and can find no artefact of the measurement to account for it, it's normal procedure to invite broader scrutiny, and this is exactly what the OPERA collaboration is doing, it's good scientific practice," said CERN Research Director Sergio Bertolucci. "If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations. That will require independent measurements."

In order to perform this study, the OPERA Collaboration teamed up with experts in metrology from CERN and other institutions to perform a series of high precision measurements of the distance between the source and the detector, and of the neutrinos' time of flight. The distance between the origin of the neutrino beam and OPERA was measured with an uncertainty of 20 cm over the 730 km travel path. The neutrinos' time of flight was determined with an accuracy of less than 10 nanoseconds by using sophisticated instruments including advanced GPS systems and atomic clocks. The time response of all elements of the CNGS beam line and of the OPERA detector has also been measured with great precision.

"We have established synchronization between CERN and Gran Sasso that gives us nanosecond accuracy, and we've measured the distance between the two sites to 20 centimetres," said Dario Autiero, the CNRS researcher who will give this afternoon's seminar. "Although our measurements have low systematic uncertainty and high statistical accuracy, and we place great confidence in our results, we're looking forward to comparing them with those from other experiments."

"The potential impact on science is too large to draw immediate conclusions or attempt physics interpretations. My first reaction is that the neutrino is still surprising us with its mysteries." said Ereditato. "Today's seminar is intended to invite scrutiny from the broader particle physics community."

The OPERA experiment was inaugurated in 2006, with the main goal of studying the rare transformation (oscillation) of muon neutrinos into tau neutrinos. One first such event was observed in 2010, proving the unique ability of the experiment in the detection of the elusive signal of tau neutrinos.

The seminar will be webcast at http://webcast.cern.ch.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Istituto Nazionale di Fisica Nucleare.

Journal Reference:

OPERA. Measurement of the neutrino velocity with the OPERA detector in the CNGS beam. arXiv.org, 2011; [link]

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Particles appear to travel faster than light: OPERA experiment reports anomaly in flight time of neutrinos

ScienceDaily (Sep. 23, 2011) — Scientists with the OPERA experiment, which observes a neutrino beam from CERN 730 km away at Italy's INFN Gran Sasso Laboratory, are presenting surprising new results (in a seminar at CERN on Sept. 23, 2011) that appear to show neutrinos traveling faster than light.

The OPERA result is based on the observation of over 15000 neutrino events measured at Gran Sasso, and appears to indicate that the neutrinos travel at a velocity 20 parts per million above the speed of light, nature's cosmic speed limit. Given the potential far-reaching consequences of such a result, independent measurements are needed before the effect can either be refuted or firmly established. This is why the OPERA collaboration has decided to open the result to broader scrutiny. The collaboration's result is available on the preprint server arXiv (http://arxiv.org/list/hep-ex/new).

"This result comes as a complete surprise," said OPERA spokesperson, Antonio Ereditato of the University of Bern. "After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation."

"When an experiment finds an apparently unbelievable result and can find no artefact of the measurement to account for it, it's normal procedure to invite broader scrutiny, and this is exactly what the OPERA collaboration is doing, it's good scientific practice," said CERN Research Director Sergio Bertolucci. "If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations. That will require independent measurements."

In order to perform this study, the OPERA Collaboration teamed up with experts in metrology from CERN and other institutions to perform a series of high precision measurements of the distance between the source and the detector, and of the neutrinos' time of flight. The distance between the origin of the neutrino beam and OPERA was measured with an uncertainty of 20 cm over the 730 km travel path. The neutrinos' time of flight was determined with an accuracy of less than 10 nanoseconds by using sophisticated instruments including advanced GPS systems and atomic clocks. The time response of all elements of the CNGS beam line and of the OPERA detector has also been measured with great precision.

"We have established synchronization between CERN and Gran Sasso that gives us nanosecond accuracy, and we've measured the distance between the two sites to 20 centimetres," said Dario Autiero, the CNRS researcher who will give this afternoon's seminar. "Although our measurements have low systematic uncertainty and high statistical accuracy, and we place great confidence in our results, we're looking forward to comparing them with those from other experiments."

"The potential impact on science is too large to draw immediate conclusions or attempt physics interpretations. My first reaction is that the neutrino is still surprising us with its mysteries." said Ereditato. "Today's seminar is intended to invite scrutiny from the broader particle physics community."

The OPERA experiment was inaugurated in 2006, with the main goal of studying the rare transformation (oscillation) of muon neutrinos into tau neutrinos. One first such event was observed in 2010, proving the unique ability of the experiment in the detection of the elusive signal of tau neutrinos.

The seminar will be webcast at http://webcast.cern.ch.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Istituto Nazionale di Fisica Nucleare.

Journal Reference:

OPERA. Measurement of the neutrino velocity with the OPERA detector in the CNGS beam. arXiv.org, 2011; [link]

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Faster computer graphics: Digitally mimicking photographic blur caused by moving objects

ScienceDaily (June 13, 2011) — Photographs of moving objects are almost always a little blurry -- or a lot blurry, if the objects are moving rapidly enough. To make their work look as much like conventional film as possible, game and movie animators try to reproduce this blur. But counterintuitively, producing blurry images is actually more computationally complex than producing perfectly sharp ones.

In August, at this year's Siggraph conference -- the premier computer-graphics conference -- researchers from the Computer Graphics Group at MIT's Computer Science and Artificial Intelligence Laboratory will present a pair of papers that describe new techniques for computing blur much more efficiently. The result could be more convincing video games and frames of digital video that take minutes rather than hours to render.

The image sensor in a digital camera, and even the film in a conventional camera, can be thought of as a grid of color detectors, each detector corresponding to one pixel in the final image. If the objects being photographed are stationary, then during a single exposure, each detector registers the color of just one point on an object's surface. But if the objects are moving, light from different points on an object, and even from different objects, will strike a single detector. The detector effectively averages the colors of all the points, and the result is blur.

Digitally rendering a frame of video is a computationally intensive process with several discrete stages. First, the computer has to determine how the objects in the scene are moving. Second, it has to calculate how rays of light from an imagined light source would reflect off the objects. Finally, it determines which rays of light would actually reach an imagined lens. If the objects in the video are moving slowly enough, the computer has to go through that process only once per frame. If the objects are moving rapidly, however, it may have to go through it dozens or even hundreds of times.

Colorfast

Given how difficult blurring is to calculate, you might think that animators would simply ignore it. But that leads to surprisingly unconvincing video. "The motion doesn't look fluid at all," says Jaakko Lehtinen, who worked on both projects as a postdoc in the Computer Graphics Group and is now a senior research scientist with graphics-chip manufacturer Nvidia.

To get a sense of what motion without blur looks like, Lehtinen says, consider the type of clay animation familiar from old movies or Christmas specials such as "Rudolph the Red-Nosed Reindeer." "This doesn't have motion blur, because the scene is actually stationary when you take the picture," Lehtinen says. "It just looks choppy. The motion doesn't look natural."

The MIT researchers took two different approaches to simplifying the computation of blur, corresponding to two different stages in the graphics-rendering pipeline. Graduate student Jonathan Ragan-Kelley is the lead author on one of the Siggraph papers, joined by associate professor Frédo Durand, who leads the Computer Graphics Group; Lehtinen; graduate student Jiawen Chen; and Michael Doggett of Lund University in Sweden. In that paper, the researchers make the simplifying assumption that the way in which light reflects off a moving object doesn't change over the course of a single frame. For each pixel in the final image, their algorithm still averages the colors of multiple points on objects' surfaces, but it calculates those colors only once. The researchers found a way to represent the relationship between the color calculations and the shapes of the associated objects as entries in a table. For each pixel in the final image, the algorithm simply looks up the corresponding values in the table. That drastically simplifies the calculation but has little effect on the final image.

Adopting the researchers' proposal would require modifying the architecture of graphics chips. "You can imagine really just going ahead and building what they suggest," says Henry Moreton, a distinguished engineer at Nvidia. "But I think that the greater value of the paper is that it points at strategies for solving these problems more elegantly, more efficiently, and more practically. Whether they manifest themselves in exactly the fashion that the paper presents is probably not that likely. But what they did is they pointed to a new way of attacking the problem."

Turning the tables

The second of the Computer Graphics Group's Siggraph papers, led by Lehtinen and also featuring Durand, Chen and two of Lehtinen's Nvidia colleagues, reduces the computational burden of determining which rays of light would reach an imagined lens. To produce convincing motion blur, digital animators might ordinarily consider the contributions that more than 100 discrete points on the surfaces of moving objects make to the color value of a single pixel. Lehtinen and his colleagues' algorithm instead looks at a smaller number of points -- maybe 16 or so -- and makes an educated guess about the color values of the points in between. The result: A frame of digital video that would ordinarily take about an hour to render might instead take about 10 minutes.

In fact, both techniques apply not only to motion blur but also to the type of blur that occurs in, say, the background of an image when the camera is focused on an object in the foreground. That, too, is something that animators seek to reproduce. "Where the director and the cinematographer choose to focus the lens, it directs your attention when you're looking at the picture in subtle ways," Lehtinen says. If an animated film has no such lapses in focus, "there's just something wrong with it," Lehtinen says. "It doesn't look like a movie." Indeed, Lehtinen says, even though the paper has yet to be presented, several major special-effects companies have already contacted the researchers about the work.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by Larry Hardesty, MIT News Office.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Faster computer graphics: Digitally mimicking photographic blur caused by moving objects

ScienceDaily (June 13, 2011) — Photographs of moving objects are almost always a little blurry -- or a lot blurry, if the objects are moving rapidly enough. To make their work look as much like conventional film as possible, game and movie animators try to reproduce this blur. But counterintuitively, producing blurry images is actually more computationally complex than producing perfectly sharp ones.

In August, at this year's Siggraph conference -- the premier computer-graphics conference -- researchers from the Computer Graphics Group at MIT's Computer Science and Artificial Intelligence Laboratory will present a pair of papers that describe new techniques for computing blur much more efficiently. The result could be more convincing video games and frames of digital video that take minutes rather than hours to render.

The image sensor in a digital camera, and even the film in a conventional camera, can be thought of as a grid of color detectors, each detector corresponding to one pixel in the final image. If the objects being photographed are stationary, then during a single exposure, each detector registers the color of just one point on an object's surface. But if the objects are moving, light from different points on an object, and even from different objects, will strike a single detector. The detector effectively averages the colors of all the points, and the result is blur.

Digitally rendering a frame of video is a computationally intensive process with several discrete stages. First, the computer has to determine how the objects in the scene are moving. Second, it has to calculate how rays of light from an imagined light source would reflect off the objects. Finally, it determines which rays of light would actually reach an imagined lens. If the objects in the video are moving slowly enough, the computer has to go through that process only once per frame. If the objects are moving rapidly, however, it may have to go through it dozens or even hundreds of times.

Colorfast

Given how difficult blurring is to calculate, you might think that animators would simply ignore it. But that leads to surprisingly unconvincing video. "The motion doesn't look fluid at all," says Jaakko Lehtinen, who worked on both projects as a postdoc in the Computer Graphics Group and is now a senior research scientist with graphics-chip manufacturer Nvidia.

To get a sense of what motion without blur looks like, Lehtinen says, consider the type of clay animation familiar from old movies or Christmas specials such as "Rudolph the Red-Nosed Reindeer." "This doesn't have motion blur, because the scene is actually stationary when you take the picture," Lehtinen says. "It just looks choppy. The motion doesn't look natural."

The MIT researchers took two different approaches to simplifying the computation of blur, corresponding to two different stages in the graphics-rendering pipeline. Graduate student Jonathan Ragan-Kelley is the lead author on one of the Siggraph papers, joined by associate professor Frédo Durand, who leads the Computer Graphics Group; Lehtinen; graduate student Jiawen Chen; and Michael Doggett of Lund University in Sweden. In that paper, the researchers make the simplifying assumption that the way in which light reflects off a moving object doesn't change over the course of a single frame. For each pixel in the final image, their algorithm still averages the colors of multiple points on objects' surfaces, but it calculates those colors only once. The researchers found a way to represent the relationship between the color calculations and the shapes of the associated objects as entries in a table. For each pixel in the final image, the algorithm simply looks up the corresponding values in the table. That drastically simplifies the calculation but has little effect on the final image.

Adopting the researchers' proposal would require modifying the architecture of graphics chips. "You can imagine really just going ahead and building what they suggest," says Henry Moreton, a distinguished engineer at Nvidia. "But I think that the greater value of the paper is that it points at strategies for solving these problems more elegantly, more efficiently, and more practically. Whether they manifest themselves in exactly the fashion that the paper presents is probably not that likely. But what they did is they pointed to a new way of attacking the problem."

Turning the tables

The second of the Computer Graphics Group's Siggraph papers, led by Lehtinen and also featuring Durand, Chen and two of Lehtinen's Nvidia colleagues, reduces the computational burden of determining which rays of light would reach an imagined lens. To produce convincing motion blur, digital animators might ordinarily consider the contributions that more than 100 discrete points on the surfaces of moving objects make to the color value of a single pixel. Lehtinen and his colleagues' algorithm instead looks at a smaller number of points -- maybe 16 or so -- and makes an educated guess about the color values of the points in between. The result: A frame of digital video that would ordinarily take about an hour to render might instead take about 10 minutes.

In fact, both techniques apply not only to motion blur but also to the type of blur that occurs in, say, the background of an image when the camera is focused on an object in the foreground. That, too, is something that animators seek to reproduce. "Where the director and the cinematographer choose to focus the lens, it directs your attention when you're looking at the picture in subtle ways," Lehtinen says. If an animated film has no such lapses in focus, "there's just something wrong with it," Lehtinen says. "It doesn't look like a movie." Indeed, Lehtinen says, even though the paper has yet to be presented, several major special-effects companies have already contacted the researchers about the work.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by Larry Hardesty, MIT News Office.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Black holes spin faster and faster

ScienceDaily (May 23, 2011) — Two UK astronomers have found that the giant black holes in the centre of galaxies are on average spinning faster than at any time in the history of the Universe. Dr Alejo Martinez-Sansigre of the University of Portsmouth and Prof. Steve Rawlings of the University of Oxford made the new discovery by using radio, optical and X-ray data. They publish their findings in the journal Monthly Notices of the Royal Astronomical Society.

There is strong evidence that every galaxy has a black hole in its centre. These black holes have masses of between a million and a billion Suns and so are referred to as 'supermassive'. They cannot be seen directly, but material swirls around the black hole in a so-called accretion disk before its final demise. That material can become very hot and emit radiation including X-rays that can be detected by space-based telescopes whilst associated radio emission can be detected by telescopes on the ground.

As well as radiation, twin jets are often associated with black holes and their accretion disks. There are many factors that can cause these jets to be produced, but the spin of the supermassive black hole is believed to be important. However, there are conflicting predictions about how the spins of the black holes should be evolving and until now this evolution was not well understood.

Dr Martinez-Sansigre and Professor Rawlings compared theoretical models of spinning black holes with radio, optical and X-ray observations made using a variety of instruments and found that the theories can explain very well the population of supermassive black holes with jets.

Using the radio observations, the two astronomers were able to sample the population of black holes, deducing the spread of the power of the jets. By estimating how they acquire material (the accretion process) the two scientists could then infer how quickly these objects are spinning.

The observations also give information on how the spins of supermassive black holes have evolved. In the past, when the Universe was half its the present size, practically all of the supermassive black holes had very low spins, whereas nowadays a fraction of them have very high spins. So on average, supermassive black holes are spinning faster than ever before.

This is the first time that the evolution of the spin of the supermassive black holes has been constrained and it suggests that those supermassive black holes that grow by swallowing matter will barely spin, while those that merge with other black holes will be left spinning rapidly.

Commenting on the new results, Dr Martinez-Sansigre said: "The spin of black holes can tell you a lot about how they formed. Our results suggest that in recent times a large fraction of the most massive black holes have somehow spun up. A likely explanation is that they have merged with other black holes of similar mass, which is a truly spectacular event, and the end product of this merger is a faster spinning black hole."

Professor Rawlings adds: "Later this decade we hope to test our idea that these supermassive black holes have been set spinning relatively recently. Black hole mergers cause predictable distortions in space and time -- so-called gravitational waves. With so many collisions, we expect there to be a cosmic background of gravitational waves, something that will change the timing of the pulses of radio waves that we detect from the remnants of massive stars known as pulsars.

If we are right, this timing change should be picked up by the Square Kilometre Array, the giant radio observatory due to start operating in 2019."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Royal Astronomical Society (RAS).

Journal Reference:

Alejo Martinez-Sansigre and Steve Rawlings. Observational constraints on the spin of the most massive black holes from radio observations. Monthly Notices of the Royal Astronomical Society, 2011 (in press) [link]

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Which technologies get better faster?

ScienceDaily (May 17, 2011) — Some forms of technology -- think, for example, of computer chips -- are on a fast track to constant improvements, while others evolve much more slowly. Now, a new study by researchers at MIT and other institutions shows that it may be possible to predict which technologies are likeliest to advance rapidly, and therefore may be worth more investment in research and resources.

In a nutshell, the researchers found that the greater a technology's complexity, the more slowly it changes and improves over time. They devised a way of mathematically modeling complexity, breaking a system down into its individual components and then mapping all the interconnections between these components.

"It gives you a way to think about how the structure of the technology affects the rate of improvement," says Jessika Trancik, assistant professor of engineering systems at MIT. Trancik wrote the paper with James McNerney, a graduate student at Boston University (BU); Santa Fe Institute Professor Doyne Farmer; and BU physics professor Sid Redner. It appears online this week in the Proceedings of the National Academy of Sciences.

The team was inspired by the complexity of energy-related technologies ranging from tiny transistors to huge coal-fired powerplants. They have tracked how these technologies improve over time, either through reduced cost or better performance, and, in this paper, develop a model to compare that progress to the complexity of the design and the degree of connectivity among its different components.

The authors say the approach they devised for comparing technologies could, for example, help policymakers mitigate climate change: By predicting which low-carbon technologies are likeliest to improve rapidly, their strategy could help identify the most effective areas to concentrate research funding. The analysis makes it possible to pick technologies "not just so they will work well today, but ones that will be subject to rapid development in the future," Trancik says.

Besides the importance of overall design complexity in slowing the rate of improvement, the researchers also found that certain patterns of interconnection can create bottlenecks, causing the pace of improvements to come in fits and starts rather than at a steady rate.

"In this paper, we develop a theory that shows why we see the rates of improvement that we see," Trancik says. Now that they have developed the theory, she and her colleagues are moving on to do empirical analysis of many different technologies to gauge how effective the model is in practice. "We're doing a lot of work on analyzing large data sets" on different products and processes, she says.

For now, she suggests, the method is most useful for comparing two different technologies "whose components are similar, but whose design complexity is different." For example, the analysis could be used to compare different approaches to next-generation solar photovoltaic cells, she says. The method can also be applied to processes, such as improving the design of supply chains or infrastructure systems. "It can be applied at many different scales," she says.

Koen Frenken, professor of economics of innovation and technological change at Eindhoven University of Technology in the Netherlands, says this paper "provides a long-awaited theory" for the well-known phenomenon of learning curves. "It has remained a puzzle why the rates at which humans learn differ so markedly among technologies. This paper provides an explanation by looking at the complexity of technology, using a clever way to model design complexity."

Frenken adds, "The paper opens up new avenues for research. For example, one can verify their theory experimentally by having human subjects solve problems with different degrees of complexity." In addition, he says, "The implications for firms and policymakers [are] that R&D should not only be spent on invention of new technologies, but also on simplifying existing technologies so that humans will learn faster how to improve these technologies."

Ultimately, the kind of analysis developed in this paper could become part of the design process -- allowing engineers to "design for rapid innovation," Trancik says, by using these principles to determine "how you set up the architecture of your system."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler.

Journal Reference:

J. McNerney, J. D. Farmer, S. Redner, J. E. Trancik. Role of design complexity in technology improvement. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1017298108

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Do microbes swim faster or slower in elastic fluids? Research answers long-standing question

ScienceDaily (May 18, 2011) — A biomechanical experiment conducted at the University of Pennsylvania School of Engineering and Applied Science has answered a long-standing theoretical question: Will microorganisms swim faster or slower in elastic fluids? For a prevalent type of swimming, undulation, the answer is "slower."

Paulo Arratia, assistant professor of mechanical engineering and applied mechanics, along with student Xiaoning Shen, conducted the experiment. Their findings were published in the journal Physical Review Letters.

Many animals, microorganisms and cells move by undulation, and they often do so through elastic fluids. From worms aerating wet soil to sperm racing toward an egg, swimming dynamics in elastic fluids is relevant to a number of facets of everyday life; however, decades of research in this area have been almost entirely theoretical or done with computer models. Only a few investigations involved live organisms.

"There have been qualitative observations of sperm cells, for example, where you put sperm in water and watch their tails, then put them in an elastic fluid and see how they swim differently," Arratia said. "But this difference has never been characterized, never put into numbers to quantify exactly how much elasticity affects the way they swim, is it faster or slower and why."

The main obstacle for quantitatively testing these theories with live organisms is developing an elastic fluid in which they can survive, behave normally and in which they can be effectively observed under a microscope.

Arratia and Shen experimented on the nematode C. elegans, building a swimming course for the millimeter-long worms. The researchers filmed them through a microscope while the creatures swam the course in many different liquids with different elasticity but the same viscosity.

Though the two liquid traits, elasticity and viscosity, sound like they are two sides of the same coin, they are actually independent of each other. Viscosity is a liquid's resistance to flowing; elasticity describes its tendency to resume its original shape after it has been deformed. All fluids have some level of viscosity, but certain liquids like saliva or mucus, under certain conditions, can act like a rubber band.

Increased viscosity would slow a swimming organism, but how one would fare with increased elasticity was an open question.

"The theorists had a lot of different predictions," Arratia said. "Some people said elasticity would make things go faster. Others said it would make things go slower. It was all over the map.

"We were the first ones to show that, with this animal, elasticity actually brings the speed and swimming efficiency down."

The reason the nematodes swam slower has to do with how viscosity and elasticity can influence each other.

"In order to make our fluids elastic, we put polymers in them," Arratia said. "DNA, for example, is a polymer. What we use is very similar to DNA, in that if you leave it alone it is coiled. But if you apply a force to it, the DNA or our polymer, will start to unravel.

"With each swimming stroke, the nematode stretches the polymer. And every time the polymers are stretched, the viscosity goes up. And as the viscosity goes up, it's more resistance to move through."

Beyond giving theorists and models a real-world benchmark to work from, Arratia and Shen's experiment opens the door for more live-organism experiments. There are still many un-answered questions relating to swimming dynamics and elasticity.

"We can increase the elasticity and see if there is a mode in which speed goes up again. Once the fluid is strongly elastic, or closer to a solid, we want to see what happens," Arratia said. "Is there a point where it switches from swimming to crawling?"

Arratia and Shen's research was supported by the National Science Foundation.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Pennsylvania.

Journal Reference:

X. Shen, P. Arratia. Undulatory Swimming in Viscoelastic Fluids. Physical Review Letters, 2011; 106 (20) DOI: 10.1103/PhysRevLett.106.208101

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Which technologies get better faster?

ScienceDaily (May 17, 2011) — Some forms of technology -- think, for example, of computer chips -- are on a fast track to constant improvements, while others evolve much more slowly. Now, a new study by researchers at MIT and other institutions shows that it may be possible to predict which technologies are likeliest to advance rapidly, and therefore may be worth more investment in research and resources.

In a nutshell, the researchers found that the greater a technology's complexity, the more slowly it changes and improves over time. They devised a way of mathematically modeling complexity, breaking a system down into its individual components and then mapping all the interconnections between these components.

"It gives you a way to think about how the structure of the technology affects the rate of improvement," says Jessika Trancik, assistant professor of engineering systems at MIT. Trancik wrote the paper with James McNerney, a graduate student at Boston University (BU); Santa Fe Institute Professor Doyne Farmer; and BU physics professor Sid Redner. It appears online this week in the Proceedings of the National Academy of Sciences.

The team was inspired by the complexity of energy-related technologies ranging from tiny transistors to huge coal-fired powerplants. They have tracked how these technologies improve over time, either through reduced cost or better performance, and, in this paper, develop a model to compare that progress to the complexity of the design and the degree of connectivity among its different components.

The authors say the approach they devised for comparing technologies could, for example, help policymakers mitigate climate change: By predicting which low-carbon technologies are likeliest to improve rapidly, their strategy could help identify the most effective areas to concentrate research funding. The analysis makes it possible to pick technologies "not just so they will work well today, but ones that will be subject to rapid development in the future," Trancik says.

Besides the importance of overall design complexity in slowing the rate of improvement, the researchers also found that certain patterns of interconnection can create bottlenecks, causing the pace of improvements to come in fits and starts rather than at a steady rate.

"In this paper, we develop a theory that shows why we see the rates of improvement that we see," Trancik says. Now that they have developed the theory, she and her colleagues are moving on to do empirical analysis of many different technologies to gauge how effective the model is in practice. "We're doing a lot of work on analyzing large data sets" on different products and processes, she says.

For now, she suggests, the method is most useful for comparing two different technologies "whose components are similar, but whose design complexity is different." For example, the analysis could be used to compare different approaches to next-generation solar photovoltaic cells, she says. The method can also be applied to processes, such as improving the design of supply chains or infrastructure systems. "It can be applied at many different scales," she says.

Koen Frenken, professor of economics of innovation and technological change at Eindhoven University of Technology in the Netherlands, says this paper "provides a long-awaited theory" for the well-known phenomenon of learning curves. "It has remained a puzzle why the rates at which humans learn differ so markedly among technologies. This paper provides an explanation by looking at the complexity of technology, using a clever way to model design complexity."

Frenken adds, "The paper opens up new avenues for research. For example, one can verify their theory experimentally by having human subjects solve problems with different degrees of complexity." In addition, he says, "The implications for firms and policymakers [are] that R&D should not only be spent on invention of new technologies, but also on simplifying existing technologies so that humans will learn faster how to improve these technologies."

Ultimately, the kind of analysis developed in this paper could become part of the design process -- allowing engineers to "design for rapid innovation," Trancik says, by using these principles to determine "how you set up the architecture of your system."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler.

Journal Reference:

J. McNerney, J. D. Farmer, S. Redner, J. E. Trancik. Role of design complexity in technology improvement. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1017298108

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View the original article here

Do microbes swim faster or slower in elastic fluids? Research answers long-standing question

ScienceDaily (May 18, 2011) — A biomechanical experiment conducted at the University of Pennsylvania School of Engineering and Applied Science has answered a long-standing theoretical question: Will microorganisms swim faster or slower in elastic fluids? For a prevalent type of swimming, undulation, the answer is "slower."

Paulo Arratia, assistant professor of mechanical engineering and applied mechanics, along with student Xiaoning Shen, conducted the experiment. Their findings were published in the journal Physical Review Letters.

Many animals, microorganisms and cells move by undulation, and they often do so through elastic fluids. From worms aerating wet soil to sperm racing toward an egg, swimming dynamics in elastic fluids is relevant to a number of facets of everyday life; however, decades of research in this area have been almost entirely theoretical or done with computer models. Only a few investigations involved live organisms.

"There have been qualitative observations of sperm cells, for example, where you put sperm in water and watch their tails, then put them in an elastic fluid and see how they swim differently," Arratia said. "But this difference has never been characterized, never put into numbers to quantify exactly how much elasticity affects the way they swim, is it faster or slower and why."

The main obstacle for quantitatively testing these theories with live organisms is developing an elastic fluid in which they can survive, behave normally and in which they can be effectively observed under a microscope.

Arratia and Shen experimented on the nematode C. elegans, building a swimming course for the millimeter-long worms. The researchers filmed them through a microscope while the creatures swam the course in many different liquids with different elasticity but the same viscosity.

Though the two liquid traits, elasticity and viscosity, sound like they are two sides of the same coin, they are actually independent of each other. Viscosity is a liquid's resistance to flowing; elasticity describes its tendency to resume its original shape after it has been deformed. All fluids have some level of viscosity, but certain liquids like saliva or mucus, under certain conditions, can act like a rubber band.

Increased viscosity would slow a swimming organism, but how one would fare with increased elasticity was an open question.

"The theorists had a lot of different predictions," Arratia said. "Some people said elasticity would make things go faster. Others said it would make things go slower. It was all over the map.

"We were the first ones to show that, with this animal, elasticity actually brings the speed and swimming efficiency down."

The reason the nematodes swam slower has to do with how viscosity and elasticity can influence each other.

"In order to make our fluids elastic, we put polymers in them," Arratia said. "DNA, for example, is a polymer. What we use is very similar to DNA, in that if you leave it alone it is coiled. But if you apply a force to it, the DNA or our polymer, will start to unravel.

"With each swimming stroke, the nematode stretches the polymer. And every time the polymers are stretched, the viscosity goes up. And as the viscosity goes up, it's more resistance to move through."

Beyond giving theorists and models a real-world benchmark to work from, Arratia and Shen's experiment opens the door for more live-organism experiments. There are still many un-answered questions relating to swimming dynamics and elasticity.

"We can increase the elasticity and see if there is a mode in which speed goes up again. Once the fluid is strongly elastic, or closer to a solid, we want to see what happens," Arratia said. "Is there a point where it switches from swimming to crawling?"

Arratia and Shen's research was supported by the National Science Foundation.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Pennsylvania.

Journal Reference:

X. Shen, P. Arratia. Undulatory Swimming in Viscoelastic Fluids. Physical Review Letters, 2011; 106 (20) DOI: 10.1103/PhysRevLett.106.208101

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Black holes spin faster and faster

ScienceDaily (May 23, 2011) — Two UK astronomers have found that the giant black holes in the centre of galaxies are on average spinning faster than at any time in the history of the Universe. Dr Alejo Martinez-Sansigre of the University of Portsmouth and Prof. Steve Rawlings of the University of Oxford made the new discovery by using radio, optical and X-ray data. They publish their findings in the journal Monthly Notices of the Royal Astronomical Society.

There is strong evidence that every galaxy has a black hole in its centre. These black holes have masses of between a million and a billion Suns and so are referred to as 'supermassive'. They cannot be seen directly, but material swirls around the black hole in a so-called accretion disk before its final demise. That material can become very hot and emit radiation including X-rays that can be detected by space-based telescopes whilst associated radio emission can be detected by telescopes on the ground.

As well as radiation, twin jets are often associated with black holes and their accretion disks. There are many factors that can cause these jets to be produced, but the spin of the supermassive black hole is believed to be important. However, there are conflicting predictions about how the spins of the black holes should be evolving and until now this evolution was not well understood.

Dr Martinez-Sansigre and Professor Rawlings compared theoretical models of spinning black holes with radio, optical and X-ray observations made using a variety of instruments and found that the theories can explain very well the population of supermassive black holes with jets.

Using the radio observations, the two astronomers were able to sample the population of black holes, deducing the spread of the power of the jets. By estimating how they acquire material (the accretion process) the two scientists could then infer how quickly these objects are spinning.

The observations also give information on how the spins of supermassive black holes have evolved. In the past, when the Universe was half its the present size, practically all of the supermassive black holes had very low spins, whereas nowadays a fraction of them have very high spins. So on average, supermassive black holes are spinning faster than ever before.

This is the first time that the evolution of the spin of the supermassive black holes has been constrained and it suggests that those supermassive black holes that grow by swallowing matter will barely spin, while those that merge with other black holes will be left spinning rapidly.

Commenting on the new results, Dr Martinez-Sansigre said: "The spin of black holes can tell you a lot about how they formed. Our results suggest that in recent times a large fraction of the most massive black holes have somehow spun up. A likely explanation is that they have merged with other black holes of similar mass, which is a truly spectacular event, and the end product of this merger is a faster spinning black hole."

Professor Rawlings adds: "Later this decade we hope to test our idea that these supermassive black holes have been set spinning relatively recently. Black hole mergers cause predictable distortions in space and time -- so-called gravitational waves. With so many collisions, we expect there to be a cosmic background of gravitational waves, something that will change the timing of the pulses of radio waves that we detect from the remnants of massive stars known as pulsars.

If we are right, this timing change should be picked up by the Square Kilometre Array, the giant radio observatory due to start operating in 2019."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Royal Astronomical Society (RAS).

Journal Reference:

Alejo Martinez-Sansigre and Steve Rawlings. Observational constraints on the spin of the most massive black holes from radio observations. Monthly Notices of the Royal Astronomical Society, 2011 (in press) [link]

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Toward faster transistors: Physicists discover physical phenomenon that could boost computers' clock speed

ScienceDaily (May 15, 2011) — In the 1980s and '90s, competition in the computer industry was all about "clock speed" -- how many megahertz, and ultimately gigahertz, a chip could boast. But clock speeds stalled out almost 10 years ago: Chips that run faster also run hotter, and with existing technology, there seems to be no way to increase clock speed without causing chips to overheat.

In this week's issue of the journal Science, MIT researchers and their colleagues at the University of Augsburg in Germany report the discovery of a new physical phenomenon that could yield transistors with greatly enhanced capacitance -- a measure of the voltage required to move a charge. And that, in turn, could lead to the revival of clock speed as the measure of a computer's power.

In today's computer chips, transistors are made from semiconductors, such as silicon. Each transistor includes an electrode called the gate; applying a voltage to the gate causes electrons to accumulate underneath it. The electrons constitute a channel through which an electrical current can pass, turning the semiconductor into a conductor.

Capacitance measures how much charge accumulates below the gate for a given voltage. The power that a chip consumes, and the heat it gives off, are roughly proportional to the square of the gate's operating voltage. So lowering the voltage could drastically reduce the heat, creating new room to crank up the clock.

MIT Professor of Physics Raymond Ashoori and Lu Li, a postdoc and Pappalardo Fellow in his lab -- together with Christoph Richter, Stefan Paetel, Thilo Kopp and Jochen Mannhart of the University of Augsburg -- investigated the unusual physical system that results when lanthanum aluminate is grown on top of strontium titanate. Lanthanum aluminate consists of alternating layers of lanthanum oxide and aluminum oxide. The lanthanum-based layers have a slight positive charge; the aluminum-based layers, a slight negative charge. The result is a series of electric fields that all add up in the same direction, creating an electric potential between the top and bottom of the material.

Ordinarily, both lanthanum aluminate and strontium titanate are excellent insulators, meaning that they don't conduct electrical current. But physicists had speculated that if the lanthanum aluminate gets thick enough, its electrical potential would increase to the point that some electrons would have to move from the top of the material to the bottom, to prevent what's called a "polarization catastrophe." The result is a conductive channel at the juncture with the strontium titanate -- much like the one that forms when a transistor is switched on. So Ashoori and his collaborators decided to measure the capacitance between that channel and a gate electrode on top of the lanthanum aluminate.

They were amazed by what they found: Although their results were somewhat limited by their experimental apparatus, it may be that an infinitesimal change in voltage will cause a large amount of charge to enter the channel between the two materials. "The channel may suck in charge -- shoomp! Like a vacuum," Ashoori says. "And it operates at room temperature, which is the thing that really stunned us."

Indeed, the material's capacitance is so high that the researchers don't believe it can be explained by existing physics. "We've seen the same kind of thing in semiconductors," Ashoori says, "but that was a very pure sample, and the effect was very small. This is a super-dirty sample and a super-big effect." It's still not clear, Ashoori says, just why the effect is so big: "It could be a new quantum-mechanical effect or some unknown physics of the material."

There is one drawback to the system that the researchers investigated: While a lot of charge will move into the channel between materials with a slight change in voltage, it moves slowly -- much too slowly for the type of high-frequency switching that takes place in computer chips. That could be because the samples of the material are, as Ashoori says, "super dirty"; purer samples might exhibit less electrical resistance. But it's also possible that, if researchers can understand the physical phenomena underlying the material's remarkable capacitance, they may be able to reproduce them in more practical materials.

Triscone cautions that wholesale changes to the way computer chips are manufactured will inevitably face resistance. "So much money has been injected into the semiconductor industry for decades that to do something new, you need a really disruptive technology," he says.

"It's not going to revolutionize electronics tomorrow," Ashoori agrees. "But this mechanism exists, and once we know it exists, if we can understand what it is, we can try to engineer it."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by Larry Hardesty, MIT News Office.

Journal Reference:

L. Li, C. Richter, S. Paetel, T. Kopp, J. Mannhart, R. C. Ashoori. Very Large Capacitance Enhancement in a Two-Dimensional Electron System. Science, 2011; 332 (6031): 825 DOI: 10.1126/science.1204168

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Toward faster transistors: Physicists discover physical phenomenon that could boost computers' clock speed

ScienceDaily (May 15, 2011) — In the 1980s and '90s, competition in the computer industry was all about "clock speed" -- how many megahertz, and ultimately gigahertz, a chip could boast. But clock speeds stalled out almost 10 years ago: Chips that run faster also run hotter, and with existing technology, there seems to be no way to increase clock speed without causing chips to overheat.

In this week's issue of the journal Science, MIT researchers and their colleagues at the University of Augsburg in Germany report the discovery of a new physical phenomenon that could yield transistors with greatly enhanced capacitance -- a measure of the voltage required to move a charge. And that, in turn, could lead to the revival of clock speed as the measure of a computer's power.

In today's computer chips, transistors are made from semiconductors, such as silicon. Each transistor includes an electrode called the gate; applying a voltage to the gate causes electrons to accumulate underneath it. The electrons constitute a channel through which an electrical current can pass, turning the semiconductor into a conductor.

Capacitance measures how much charge accumulates below the gate for a given voltage. The power that a chip consumes, and the heat it gives off, are roughly proportional to the square of the gate's operating voltage. So lowering the voltage could drastically reduce the heat, creating new room to crank up the clock.

MIT Professor of Physics Raymond Ashoori and Lu Li, a postdoc and Pappalardo Fellow in his lab -- together with Christoph Richter, Stefan Paetel, Thilo Kopp and Jochen Mannhart of the University of Augsburg -- investigated the unusual physical system that results when lanthanum aluminate is grown on top of strontium titanate. Lanthanum aluminate consists of alternating layers of lanthanum oxide and aluminum oxide. The lanthanum-based layers have a slight positive charge; the aluminum-based layers, a slight negative charge. The result is a series of electric fields that all add up in the same direction, creating an electric potential between the top and bottom of the material.

Ordinarily, both lanthanum aluminate and strontium titanate are excellent insulators, meaning that they don't conduct electrical current. But physicists had speculated that if the lanthanum aluminate gets thick enough, its electrical potential would increase to the point that some electrons would have to move from the top of the material to the bottom, to prevent what's called a "polarization catastrophe." The result is a conductive channel at the juncture with the strontium titanate -- much like the one that forms when a transistor is switched on. So Ashoori and his collaborators decided to measure the capacitance between that channel and a gate electrode on top of the lanthanum aluminate.

They were amazed by what they found: Although their results were somewhat limited by their experimental apparatus, it may be that an infinitesimal change in voltage will cause a large amount of charge to enter the channel between the two materials. "The channel may suck in charge -- shoomp! Like a vacuum," Ashoori says. "And it operates at room temperature, which is the thing that really stunned us."

Indeed, the material's capacitance is so high that the researchers don't believe it can be explained by existing physics. "We've seen the same kind of thing in semiconductors," Ashoori says, "but that was a very pure sample, and the effect was very small. This is a super-dirty sample and a super-big effect." It's still not clear, Ashoori says, just why the effect is so big: "It could be a new quantum-mechanical effect or some unknown physics of the material."

There is one drawback to the system that the researchers investigated: While a lot of charge will move into the channel between materials with a slight change in voltage, it moves slowly -- much too slowly for the type of high-frequency switching that takes place in computer chips. That could be because the samples of the material are, as Ashoori says, "super dirty"; purer samples might exhibit less electrical resistance. But it's also possible that, if researchers can understand the physical phenomena underlying the material's remarkable capacitance, they may be able to reproduce them in more practical materials.

Triscone cautions that wholesale changes to the way computer chips are manufactured will inevitably face resistance. "So much money has been injected into the semiconductor industry for decades that to do something new, you need a really disruptive technology," he says.

"It's not going to revolutionize electronics tomorrow," Ashoori agrees. "But this mechanism exists, and once we know it exists, if we can understand what it is, we can try to engineer it."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by Larry Hardesty, MIT News Office.

Journal Reference:

L. Li, C. Richter, S. Paetel, T. Kopp, J. Mannhart, R. C. Ashoori. Very Large Capacitance Enhancement in a Two-Dimensional Electron System. Science, 2011; 332 (6031): 825 DOI: 10.1126/science.1204168

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here