Technology Trends

It’s not the first time that physicists claim that the speed of light can be modified, and even exceed the theoretical limit called c without violating Einstein’s laws of relativity (check for example this article from two years ago). Now, researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland, claim that light can travel faster than light!. They were able to control the speed of light in an off-the-shelf optical fiber. They said that they did “slow a light signal down by a factor of 3.6 (or about 71,000 km/s), creating a sort of temporary “optical memory.” On the other hand, they also did create “extreme conditions in which the light signal travelled faster than 300 million meters a second.” As they don’t give any numbers for this upper limit, you have to trust them. Anyway, these results are important because they were achieved using off-the-shelf optical fibers, opening the way for future super fast all-optical routers. Update (August 22, 2005): Luc Thévenaz sent me insightful comments about this post. You’ll find them at the end of this entry.

So what have done Luc Thévenaz and his fellow researchers in the EPFL’s Nanophotonics and Metrology laboratory (page in French)?

The telecommunications industry transmits vast quantities of data via fiber optics. Light signals race down the information superhighway at about 186,000 miles per second. But information cannot be processed at this speed, because with current technology light signals cannot be stored, routed or processed without first being transformed into electrical signals, which work much more slowly. If the light signal could be controlled by light, it would be possible to route and process optical data without the costly electrical conversion, opening up the possibility of processing information at the speed of light.

This is exactly what the EPFL team has demonstrated. Using their Stimulated Brillouin Scattering (SBS) method, the group was able to slow a light signal down by a factor of 3.6, creating a sort of temporary”optical memory.” They were also able to create extreme conditions in which the light signal travelled faster than 300 million meters a second. And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn’t move over – relativity isn’t called into question, because only a portion of the signal is affected.

Anyway, the real value of this research doesn’t come from light travelling faster than c, but from light travelling slower.

Slowing down light is considered to be a critical step in our ability to process information optically. The US Defense Advanced Research Projects Agency (DARPA) considers it so important that it has been funnelling millions of dollars into projects such as”Applications of Slow Light in Optical Fibers” and research on all-optical routers. To succeed commercially, a device that slows down light must be able to work across a range of wavelengths, be capable of working at high bit-rates and be reasonably compact and inexpensive.

The EPFL team has brought applications of slow light an important step closer to this reality. And Thévenaz points out that this technology could take us far beyond just improving on current telecom applications. He suggests that their method could be used to generate high-performance microwave signals that could be used in next-generation wireless communication networks, or used to improve transmissions between satellites.

The research work has been published by Applied Physics Letters in its August 22, 2005 issue under the name “Optically controlled slow and fast light in optical fibers using stimulated Brillouin scattering” (Volume 87, Issue 8, Article 081113). Here is a link to the abstract which is reproduced below for your convenience.

We demonstrate a method to achieve an extremely wide and flexible external control of the group velocity of signals as they propagate along an optical fiber. This control is achieved by means of the gain and loss mechanisms of stimulated Brillouin scattering in the fiber itself.

Our experiments show that group velocities below 71 000 km/s on one hand, well exceeding the speed of light in vacuum on the other hand and even negative group velocities can readily be obtained with a simple benchtop experimental setup. We believe that the fact that slow and fast light can be achieved in a standard single-mode fiber, in normal environmental conditions and using off-the-shelf instrumentation, is very promising for a future use in real applications.

In this abstract, as in the news release, the researchers give a number for “group velocities” slower than c, but not a single one for those faster than c. I wonder why…

Update (August 22, 2005): Here are Luc Thévenaz’s comments in reaction to the above note, which he nicely allowed me to reproduce.

Most of your comments are right, just be aware that what is really important for applications is delaying and advancing a signal, not the real speed of propagation. This makes possible a synchronisation of optical signals, that was impossible to realize so far with a control by light.

You look very suspicious about our capability to propagate faster than the speed of light in vacuum and you wonder why we mentioned no figure about this. Hmmm, I think you were a bit lazy and you did not read entirely our APL article. The answer is in the 3 last paragraphs, read carefully. We state clearly that we could achieve an infinite and even negative group velocity! We even show a graph of our measurements. We also give explanations why this does not break the principles of relativity and causality in the next paragraph and information still propagates slowlier than the vacuum light velocity.

I just want to mention that what we have just reported experimentally was already predicted theoretically and fully explained during the 1910s by Leon Brillouin and Arnold Sommerfeld. Nothing new and no paradox, there is nothing magic behind and no theory needs to be revisited.

Finally, Luc sent me a copy of the full APL paper. Here is a link to this paper (PDF format, 3 pages, 75 KB).

Sources: EPFL news release, August 19, 2005; and various web sites

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In all networks, like road or airline traffic networks, the Internet, cancer tumors or industry supply chains, you need to pass packets from node to node, such as cars, information or data. But which are the most efficient, decentralized networks or hub-like centralized ones? According to Technology Research News (TRN), researchers from Oxford University, U.K., have designed a model which maps traffic congestion. This model combines roads going through the center of a city and other ones avoiding it. And they found that, from a cost point of view, it would be sometimes better to close roads going through cities than adding more. They also think that these conclusions can be applied to almost all kinds of networks, biological ones or created by humans. Read more…

Here are two of the opening paragraphs of the TRN article.

Researchers from Oxford University in England have tackled the problem [of network optimization] by examining the congestion costs within a network model that combines paths that go around the perimeter of the network and central hubs that provide shorter paths through the network. Real-world networks are too complicated to describe exactly mathematically. The researchers’ model is simple enough to solve exactly, yet realistic enough to provide insights into real networks.

The research is aimed at finding ways to ease bottlenecks in networks involving manufacturing, the Internet and traffic, and ways to disrupt networks like tumor blood flow and terrorist supply chains. The findings could also help design better networks.

Below are two examples of networks, the first one being a model of traffic analysis, while the second one is a real natural network (Credit: Oxford University).

On the figure above, the model network shows transport pathways through the central hub (thick lines) and around the ring (thin lines). The graph itself shows there is an optimal value for the number of connections, in this case 44 connections for 1,000 nodes.

And this photon scintillation image shows the nutrient distribution within a laboratory-grown fungus Phanerochaete velutina. Nutrient density increases going from blue to green to red.

As you can see from the network model above, traffic congestion in a city would increase if the number of roads to the center also increases after a certain point.

The model showed that above a certain number of roads to the center, adding a new road always increases the bottleneck to such an extent that the added benefit of a new route is outweighed by the time delay due to increased congestion in the center. “The interesting and counter-intuitive result that we found is that in such situations we should actually reduce the number of roads connecting to the center,” said Neil Johnson, Professor of Physics at Oxford University.

The problem can also be turned on its head, said Johnson. “Given the number of roads which exists to the center and which we assume cannot easily be changed, what cost should be imposed for passing through the center [so] that drivers between A and B experience a minimum journey time,” he said. “This charge could be an artificially induced time-delay — lights or ramps with long waiting times — or monetary.”

The researchers have applied their model to London, where you have to pay £5 to cross the center with your car, and concluded that such a flat fee leads to some inefficiencies.

The researchers’ model showed that in London, where a flat fee of five pounds is charged for passing through the center, a usage-dependent cost would make the network more efficient. “These costs could be advertised on electronic boards around the ring road so that people decide ahead of time whether to use the center or not,” said Johnson.

If you want to learn more about this research, the latest work has been published by Physical Review Letters in February 2005 under the title “Effect of Congestion Costs on Shortest Paths Through Complex Networks” (Volume 94, Number 5, Article 058701, February 11, 2005). Here are two links to the abstract and to the full paper — thanks to arXiv.org (PDF format, 4 pages, 242 KB). The above illustrations come from this paper.

Finally, here is a link to an article from New Scientist about the same subject, “New roads can cause congestion,” published on February 1, 2005

Sources: Kimberly Patch, Technology Research News, July 27/August 3, 2005; and various web sites

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• Nature
  
  
• Networking
  
  
• Physics
  
  
• Social Networks
  
  
• Transportation
  

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This story could come from the imagination of a screenwriter working on the next James Bond movie, but it’s reality. Japanese physicists have found a way to store data inside your fingernails by using lasers. And, more importantly, they were able to read this data by using an optical microscope. Technology Research News reports that storing data in our fingernails could lead to new ways of authentication. Of course, data is only available for six months. After that the fingernail has grown and the data has disappeared. Still, the researchers think that such a method could have some practical implementations within three years.

Here is the opening of the article.

Researchers from the University of Tokushima and Hokkaido University have demonstrated that it is possible to read data written into a human fingernail using a laser, much like information is written on a rewritable compact disc. The data is read using an optical microscope.

And how does this method work?

[The researchers] wrote dot patterns into a fingernail using a laser that emitted pulses lasting a few million billionths of a second. The molecules of the fingernail that were hit by the laser became ionized, and because ionized molecules repulse each other, they caused a tiny explosion. The explosion changed the structure of the material at that location by decomposing the keratin protein molecules located there. These areas can be read because they fluoresce, or absorb and emit light, at a higher rate than the surrounding fingernail material.

And how much data can they store?

Two gigabits of data can be written per cubic centimeter of fingernail using these size dots. Today’s compact discs hold about 5.6 gigabits of data. A practical fingernail recording area of 5 millimeters by 5 millimeters by one tenth of a millimeter deep would hold 5 megabits of data, or about 300 pages of text.

Of course, this data is secure, at least for the duration of the life of your fingernails.

The researchers’ proof-of-concept samples could still be read 172 days after recording. This is probably the practical limit of fingernail storage because after six months a fingernail has grown enough to be completely replaced.

Will this method for carrying personal data will really be used within three years as are thinking the researchers? I’m not sure.

If you want to learn more about this technology, the latest research work has been published by Optics Express in June 2005 under the title “Three-dimensional optical memory using a human fingernail” (Vol. 13, No. 12, Pages 4560 - 4567, June 13, 2005). Here are two links to the abstract and to the full paper (PDF format, 8 pages, 1.11 MB).

And here are two links to previous papers from 2004 about the same subject, “Optical Bit Recording in a Human Fingernail” and “Processing Structures on Human Fingernail Surfaces Using a Focused Near-Infrared Femtosecond Laser Pulse.”

Sources: Kimberly Patch, Technology Research News, July 27/August 3, 2005; and various web sites

Related stories can be found in the following categories.

• Optics
  
  
• Photonics
  
  
• Physics
  
  
• Security
  
  
• Storage
  

And remember that comments are no longer accepted here because of a vandal. If you want to tell me something about this post, please go to the bottom right of this page and send me an e-mail.

Scientists at the University of Manchester, in the UK, have discovered a new class of materials which are one atom thick and exhibit properties previously never thought possible. With these new materials, they are promising us a ‘new industrial revolution.’ Not only these new materials are ultra-thin, but they can also be ultra-strong, highly-insulating or highly-conductive. Apparently, this new class of materials has been validated by the scientific community, and even if some applications are probably decades away, you can expect to see ‘ultra-fast transistors, micromechanical devices and nano-sensors based on the discovered one-atom-thick crystals already in a few years time.’ Read more…

Here is the introduction of the news release from the University of Manchester.

Scientists at The University of Manchester have discovered a new class of materials which have previously only existed in science fiction films and books.

A team of British and Russian scientists led by Professor Andre Geim, [director of the Manchester Centre for Mesoscience and Nanotechnology,] have discovered a whole family of previously unknown materials, which are one atom thick and exhibit properties which scientists had never thought possible.

After this press release lingo, let’s move — gradually — to some more technical details.

The materials have been created by extracting individual atomic planes from conventional bulk crystals by using a technique called ‘micromechanical cleavage’. Depending on a parent crystal, their one-atom-thick counterparts can be metals, semiconductors, insulators, magnets, etc. Previously, it was thought that such thin materials could not exist in principle, but the research team have, for the first time, demonstrated that they are not only possible but fairly easy to make.

Below are some pictures of these very small two dimensional crystals (Credit for images and legend: University of Manchester).

[Here you can see] single-layer crystallites of (a) NbSe₂, (b) graphite, (c) Bi₂Sr₂CaCu₂O_x and (d) MoS₂ visualized by AFM (a,b), SEM (c) and in an optical microscope (d). All scale bars are 1µm.

Dr Kostya Novoselov, a key investigator in this research, added: “Probably the most important part is that our discovery is not limited to just one or two new materials. It is a whole class of new materials, thousands of them. And they have a variety of properties, allowing one to choose a material most appropriate for a particular application.

This fascinating research work has been published by the Proceedings of the National Academy of Sciences (PNAS) in its July 18, 2005 issue under the name “Two-dimensional atomic crystals.” Here is a link to the abstract.

We report free-standing atomic crystals that are strictly 2D and can be viewed as individual atomic planes pulled out of bulk crystals or as unrolled single-wall nanotubes. By using micromechanical cleavage, we have prepared and studied a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides. These atomically thin sheets (essentially gigantic 2D molecules unprotected from the immediate environment) are stable under ambient conditions, exhibit high crystal quality, and are continuous on a macroscopic scale.

And here is a link to the full paper from which the above figure has been extracted. Below is the conclusion of this paper.

We have demonstrated the existence of 2D atomic crystals that can be prepared by cleavage from most strongly-layered materials. It is most unexpected if not counterintuitive that isolated 2D crystals can be stable at room temperature and in air, leaving aside the fact that they maintain macroscopic continuity and such high quality that their carrier mobilities remain almost unaffected. The found class of 2D crystals offers a wide choice of new materials parameters for possible applications and promises a wealth of new phenomena usually abundant in 2D systems. We believe that, once investigated and understood, 2D crystals can also be grown in large sizes required for industrial applications, matching the progress achieved recently for the case of single-wall nanotubes.

Finally, even if these new materials are only one atom thick, they still have three dimensions. The idea of 2D crystals and materials in our 3D world would be too disturbing. What do you think of these discoveries? Can we really talk about ‘flat’ materials? And will this research lead to a new industrial revolution? Please post your comments below.

Sources: University of Manchester news release, July 18, 2005; and various web sites

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• Future
  
  
• Materials
  
  
• Nanotechnology
  
  
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• Science
  

Surveying and measuring buildings don’t look like sexy occupations. However, with the current boom of real estate prices in many countries, it’s a good idea to hire a professional surveyor to measure a future property and to avoid to pay some extra square meters for several thousand dollars each. And now, an Israeli company, EZ2CAD, has developed a new system which can measure accurately an apartment inside a building, without the limitations of the current (and more expensive) systems. In this article, IsraCast says that the new device is composed of two units, a base station and a lightweight mobile unit called Rover. Besides being as accurate and cheaper as current systems, this device also creates a CAD model directly usable by a software such as AutoCAD to build a 3D model in real time. It should become available in about two years for a starting price of $3,000. Read more…

Before going further, here is what you can read about modern surveying technologies in this page at Wikipedia.

Modern surveying utilizes an instrument called a total station, a small telescope equipped with an electronic distance-measuring device (EDMD) and set up on a tripod, although the modern use of satellite positioning systems, such as a Global Positioning System (GPS), is also well established, with the robotic total station becoming widely used. Though GPS systems have increased the speed of surveying, they are still only accurate to about 20 mm. It is because of this that EDMDs have not been completely phased out. Robotics allows surveyors to gather precise measurements without extra workers to look through and turn the telescope or record data.

So how does this new system work?

To overcome these limitations a team of Israeli professional surveyors and engineers set out to create a revolutionary new device called QuickSurveyor. The new system is composed of two units, a base station and a lightweight mobile unit called Rover. The Base station is essentially a 50cm high metallic pyramid with nine tiny RF and ultra sound transmitters / receivers built into it.

The Rover is a portable unit shaped like a telescopic rod 1meter in length, which can extend up to 3m to help measure high ceilings, and other hard to reach places. The rod includes 3 sensors triangular in shape and can be aided by laser distance meter to increase its range. The Rover unit can also include a handheld computer which shows the measurements’ progress in real time.

Below is a picture of the base station composed of its three base beacons and its nine radio transmitters (Credit: EZ2CAD).

Now, what about the performance of QuickSurveyor?

In the current prototype stage of development, the Rover can operate in a radius of approximately 30 m from the base station and create a 3D model of the measured area with an accuracy of about 2 cm within less than a second. In the finished product the accuracy level should improve to about 5 mm (almost the level of accuracy of the much more expensive TS system).

On its web site, EZ2CAD mentions a precision of 1 millimeter and a range of 200 meters, but these are probably of the future version of the product.

And by the way, when will this product be available?

The company plans to market its innovative system in about two years. [...] The estimated price of the commercial version should be between $3,000 and $10,000 depending on the system configuration.

Even if this system is not currently available, EZ2CAD is pretty optimistic about its potential market, and gives numbers I am unable to confirm from other sources.

EZ2CAD advisor Benny Marcus told Isracast that the market for surveying systems like the RTK-GPS and the QuickSurveyor is currently estimated to be more than $3 billion annually and should grow to more than $5 billion by 2008.

Finally, if you want more information about this system, including animations, please visit these two pages, QuickSurveyor Review and QS4AsBuilt.

Sources: Iddo Genuth, IsraCast, July 1, 2005; and various web sites

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• Architecture
  
  
• Engineering
  
  
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• Vision and Visualization Apps
  

City street networks are similar to other information networks, such as the Internet or social networks. Street and roads are the links while the crossroads are the nodes of these networks. So it is tempting to use physics to map city complexity, as is reporting Technology Research News. Several physicists from Sweden and Denmark have compared the complexity of finding an address in Manhattan and in several Swedish cities. Not surprisingly, Manhattan, with its checkered grid plan, is easier to navigate than the older European cities. The scientists think their model could be “used to allow city planners to see how street changes affect navigability.” But as cities don’t change very fast, it’s doubtful that this method can be used efficiently anytime soon. But read more…

Here is how Technology Research News describes the method used.

The information needed to navigate in a city can be used to quantify and compare the complexity of cities, said Martin Rosvall, a researcher at Umeå University [in Sweden]. The method could eventually be used to allow city planners to see how street changes affect navigability and could also be used to make other types of networks — like supermarket aisles and airways — work more efficiently, he said.

The researchers’ model assumes that a person traveling along the streets of the city gets all travel directions in the form of the sequence of roads that lead to the target road. In networking terms, these sequences are sets of nodes linked by intersections. From this perspective, all roads are the same regardless of how long they are. The number of intersections between roads is the measure of the information distance between them. This makes sense intuitively; the more turns there are along a route, the harder it is to follow.

The illustration describes the process used by the researchers (Credit: Martin Rosvall and his colleagues).

This figure illustrates a visitor’s perspective of an unknown city (a). The visitor asks a citizen about the way to a specific street. The citizen answers based on its perspective of the city as in (b), or rather the higher abstraction level in (c). This level is the dual map of the city, a network where streets are identified as nodes and intersections between streets as links between the nodes. We use this level to quantify the search information in (d): The minimum number of yes/no questions (bits) the visitor must ask the citizen to find a specific street (log₂ 36 bits from s to t).

Let’s move back to the Technology Research News article.

The model shows each main road as a central hub and each crossroad as a peripheral node connected to the hub. A grid of streets appears as a ring of nodes. Connections between streets form a many-pointed star inside the ring, with each of the star’s points meeting the ring at a node.

The researchers’ model confirmed the widely-held view that the roads of Manhattan are simpler in terms of information handling than cities with complicated road-construction histories. “Historical cities have an overabundance of short streets that make the cities more complex in the sense that they increase the information distance between streets,” said Rosvall.

In “The urban maze,” published on August 13, 2004 by Nature, Philip Ball, who read an early publication of this research work, added that you “don’t [have to] feel bad if you often get lost in cities.”

Rosvall, of Umeå University in Sweden, and his co-workers have tried to figure out why it is so hard for us to find our way around cities. Of course, the obvious answer is that cities have a lot of streets. And particularly if you live in an old city like London or Athens, those streets are messily arranged. But it turns out that the problem is a lot worse than that.

And he explains why the researchers have found it was more difficult to navigate a real city than a randomized one.

The crucial characteristic that complicates cities seems to be their inhomogeneity. A random network is more or less equally random everywhere. But cities, especially ones with a long history, have local “islands” of dense interconnections, containing streets that are hidden away in corners.

The research work has been published by Physical Review Letters on January 19, 2005 under the name “Networks and Cities: An Information Perspective.” Here is a link to the abstract.

Traffic is constrained by the information involved in locating the receiver and the physical distance between sender and receiver. We here focus on the former, and investigate traffic in the perspective of information handling. We replot the road map of cities in terms of the information needed to locate specific addresses and create information city networks with roads mapped to nodes and intersections to links between nodes. These networks have the broad degree distribution found in many other complex networks. The mapping to an information city network makes it possible to quantify the information associated with locating specific addresses.

The full paper is also available on line, either in a short version (PDF format, 1 page, 206 KB) or a longer one (PDF format, 4 pages, 237 KB).

The above illustration comes from the short version of this technical paper.

Sources: Kimberly Patch, Technology Research News, June 29/July 6, 2005; and various web sites

Related stories can be found in the following categories.

• Networking
  


• Physics
  


• Social Networks
  


• Transportation
  

Once again, man is imitating nature for the best. A team of Dutch physicists has created artificial cricket hairs, which are among the most sensitive sound detectors on Earth. These artificial sensory hair systems will help to develop sensor arrays useful for a variety of applications. For example, these sensor arrays could be used to visualize airflow on surfaces, such as an aircraft fuselage. But more importantly, this “could lead to a new generation of cochlear implants, for people with severe hearing problems.” Even if it doesn’t happen overnight, the low energy consumption and costs of fabrication are excellent news for deaf people. Read more…

First, let’s look at how real crickets are using their hairs.

Crickets spend most of their lives on the ground, making them vulnerable to wandering and flying predators. Species such as the wood cricket Nemobius sylvestris have developed a pair of hairy appendages at the abdominal end of their body called cerci, which are incredibly good at detecting small fluctuations in air currents — the kind that might be caused by the beating of a wasp’s wings or the jump of an attacking spider.

On the figure below, you can see the sensory hairs of the cricket (Credit: University of Twente, The Netherlands).

The sensory hairs of the cricket are situated on the back of the cricket’s body on appendices called cerci. [...] Each hair is lodged in a socket, guiding the hair to move in a preferred direction. The hair is held in its socket by an elastic material surrounding the base. Airflow causes a neuron to be fired, by rotation of the hair base. The cricket is able to pinpoint low-frequency sound from any given direction, by using the combined neural information of all sensory hairs.

Now, let’s focus on how these Dutch physicists have created artificial cricket hairs.

Physicists at the University of Twente in the Netherlands have now succeeded in building artificial sensory hair systems, which they hope will enable them to unravel the underlying process and develop sensor arrays with a variety of important applications.

The Twente team built a mechanical array with up to a few hundred artificial hairs using technologies often referred to as MEMS technology. The sensors are made by depositing and structuring various thin layers of electrically insulating and conducting materials, creating structured electrodes on a suspended membrane. The structured electrodes form two capacitors with the underlying substrate.

Below is a picture of an array of spiral-suspended sensory hairs, obtained through “a relatively simple fabrication process” (Credit: University of Twente, The Netherlands).

The news release gives some more details, but for more information, the research work has been published on June 20, 2005 by the Journal of Micromechanics and Microengineering under the name “Artificial sensory hairs based on the flow sensitive receptor hairs of crickets.” Here is a link to the abstract.

This paper presents the modelling, design, fabrication and characterization of flow sensors based on the wind-receptor hairs of crickets. Cricket sensory hairs are highly sensitive to drag-forces exerted on the hair shaft. Artificial sensory hairs have been realized in SU-8 on suspended Si_xN_y membranes. The movement of the membranes is detected capacitively. Capacitance versus voltage, frequency dependence and directional sensitivity measurements have been successfully carried out on fabricated sensor arrays, showing the viability of the concept.

And if you’re a registered member of the Institute of Physics, here is a link to the full paper (PDF format, 7 pages, 686 KB) (you can register for free from the abstract link). The above illustrations were extracted from this paper.

Finally, you can find other technical information on the CICADA project page at the University of Twente — CICADA standing for ” Cricket Inspired perCeption and Autonomous Decision Automata.”

Sources: Institute of Physics news release, June 20, 2005; and various web sites

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• Engineering
  


• Medicine
  


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• Sensors
  

Imagine a gun sending bullets at 34 kilometers per second, faster than Earth moves through space. This is the new speed record recently broken by the Z machine at Sandia National Laboratories (SNL). With this machine, Sandia researchers have “accelerated a small plate from zero to 76,000 mph in less than a second.” But not for long: their bullets are very small aluminum plates — only 30 mm by 15 mm in cross-section, and 850 microns thick. And the “bullets” don’t go very far. They can strike their targets after only five millimeters, but their impacts create incredible shock waves, reaching up to 15 million times the atmospheric pressure. Among other things, the researchers hope that their machine will help them to stabilize the U.S. nuclear stockpile without having to explode a nuclear weapon or to better understand what’s inside Saturn and Jupiter. Read more…

Here are the opening paragraphs of the SNL news release.

Sandia National Labs has accelerated a small plate from zero to 76,000 mph in less than a second.

The speed of the thrust was a new record for Sandia’s Z Machine — sometimes referred to as the fastest gun in the West. Actually the fastest in the world, it is now able to propel small plates at 34 kilometers a second, faster than the 30 km/sec that Earth travels through space in its orbit about the sun, 50 times faster than a rifle bullet, and three times the velocity needed to escape Earth’s gravitational field.

This spectacular picture shows the “arcs and sparks” produced during the Z machine shootings (Credit: Sandia National Laboratories). And here is a link to a larger version (2.52 MB).

The picture above shows Marcus Knudson, Sandia researcher and lead scientist for this project, with “the Z insert that sends flyer plates hurling at phenomenal speeds” (Credit: Randy Montoya/Sandia National Laboratories). And here is a link to a much larger version (710 KB).

Here is some more technical information.

The plates are small — only 30 mm by 15 mm in cross-section, and 850 microns thick. The trick in accelerating the fragile aluminum plates at 10-to-the-10th Gs (force of Earth’s gravity) without vaporizing them lies in the finer control now achievable of the magnetic field pulse driving the flight.

The arrival of energy at the target is staggered over three hundred nanoseconds, so that the amperage arrives less like a brick wall that would vaporize the plate and more in controllable increments.

All these numbers are impressive, but what can we expect from such a system? Here is the SNL answer.

The immediate purpose of these very rapid flights is to help understand the extreme conditions found within the interiors of the giant planets Saturn and Jupiter, hasten the achievement of virtually unlimited energy through peacetime atomic fusion, and provide more information about the condition of the U.S. nuclear stockpile without having to explode a nuclear weapon.

As I’m not a nuclear physicist, I wouldn’t have immediately thought of these possible usages. But after all, they’re the specialists.

And they still have other tricks in their bags. They want to achieve plate velocities of 45 to 50 kilometers per second within a year.

Sources: Sandia National Laboratories news release, via EurekAlert!, June 7, 2005; and SNL website

Related stories can be found in the following categories.

• Energy
  
  
• Nuclear
  
  
• Physics
  
  
• Space
  

It’s not the first time I’m mentioning the Virgo Consortium and how it is dedicated to look at the early stages of our universe (read here or there). But now, the Telegraph, U.K., tells us that these astrophysicists have completed the Millennium Run simulation which shows how our universe was looking 13.7 billion years ago. And if like me, you like big numbers, the whole simulation is the result of 500,000 trillion calculations done at the Max Planck Institute for Astrophysics which adds that their supercomputer simulation explains the formation of galaxies and quasars just after the Big Bang. Read more…

These opening paragraphs of the Telegraph article will give you an idea of the size of this simulation.

It is the result of 500,000,000,000,000,000 (500,000 trillion) calculations made by one of the biggest supercomputers in Europe after it was given information on the current composition of the universe, the microwave radiation left over after the Big Bang and the laws of physics.

The ultra-high-resolution simulation was created by tracking 10 billion particles of dark matter, the mysterious and invisible material that spreads out across the universe in gigantic strands, through the evolution process.

They focused on the evolution of a cubic region measuring two billion light years on each side — about 0.5 per cent of the universe — from just a few hundred million years after the Big Bang until the present.

You’ll find many images and movies on this page. This particular picture shows a large-scale light distribution in the Universe (Credit: Max Planck Institute for Astrophysics). And if you’re interested, you’ll also find a huge version of the poster of the Millennium Run in A0 format — for 280 MB.

The Max Planck Institute gives additional details about the simulation.

The Virgo consortium, an international group of astrophysicists from Germany, the UK, Canada and the USA has just released first results from the largest simulation ever of cosmic structure growth and of galaxy and quasar formation.

This “Millennium Run” used more than 10 billion particles to trace the evolution of the matter distribution in a cubic region of the Universe over 2 billion light-years on a side. It kept busy the principal supercomputer at the Max Planck Society’s Supercomputing Centre in Garching, Germany for more than a month.

By applying sophisticated modelling techniques to the 25 Tbytes of stored output, Virgo scientists are able recreate evolutionary histories both for the 20 million or so galaxies which populate this enormous volume and for the supermassive black holes which occasionally power quasars at their hearts.

The research work makes the cover story of the June 2 issue of Nature under the title “Evolution of the universe.”

Here is a link to the abstract of the Virgo paper, “Simulations of the formation, evolution and clustering of galaxies and quasars,” which “shows how comparing such simulated data to large observational surveys can clarify the physical processes underlying the buildup of real galaxies and black holes,” according to the Max Planck Institute.

Sources: Nic Fleming, Telegrapgh.co.uk, June 2, 2005; Max Planck Institute for Astrophysics Press Release, June 2, 2005; and various websites

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IsraCast is a Jerusalem-based multimedia network and one of its reporters just wrote an article about a dream come true, “Like a Fish: Revolutionary Underwater Breathing System.” An Israeli inventor, Alan-Izhar Bodner, “has developed a breathing apparatus that will allow breathing underwater without the assistance of oxygen tanks.” This invention is based on how fish are breathing, picking the air which is dissolved in the water. Right now, a prototype has been built which uses rechargeable batteries and which will allow for one hour of diving time. But don’t run to your diving store yet, this system will only be available in a few years. Read more…

The author, Iddo Genuth, first looks at the limitations of current underwater breathing methods: the amount of time a diver can stay underwater; the dependence on oxygen refueling facilities; and the actual use of oxygen tanks underwater.

Of course, many engineers around the world have tried to design better and lighter systems. But now, Alan-Izhar Bodner, has developed his invention by looking at how fish are breathing, explains Genuth.

Fish do not perform chemical separation of oxygen from water; instead they use the dissolved air that exists in the water in order to breathe. In the ocean the wind, waves and underwater currents help spread small amounts of air inside the water. Studies have shown that in a depth of 200m below the sea there is still about 1.5% of dissolved air. This might not sound like much but it is enough to allow both small and large fish to breathe comfortably underwater. Bodner’s idea was to create an artificial system that will mimic the way fish use the air in the water thus allowing both smaller submarines and divers to get rid of the large, cumbersome oxygen tanks.

The idea really sounds neat, but how will it be exploited?

Bodner has already built and tested a laboratory model and he is on the path to building a full-scale prototype. Patents for the invention have already been granted in Europe and a similar one is currently pending examination in the U.S. Meetings have already been held with most major diving manufacturers as well as with the Israeli Navy. Initial financial support for the project has been given by Israel Ministry of Industry and Commerce and Bodner is currently looking for private investors to help complete his project.

This is a photograph of the prototype that the inventor sent to IsraCast (Credit: Alan-Izhar Bodner). As says Iddo Genuth, there is “not really much to look at” but it’s a first draft of the device. We’ll see how it goes in the coming years.

This method for breathing underwater was patented in Europe in 2002 and 2003. For more information, you can use the Online European Patent Register search engine. You just have to enter the application number “EP20010996491″ without quotes.

For a quicker access, here are the direct links to this patent, “Open-Circuit Self-Contained Underwater Breathing Apparatus,” referenced as WO0240343 (May 23, 2002) or EP1343683 (September 17, 2003).

Here is the abstract.

A self-contained open-circuit breathing apparatus for use within a body of water naturally containing dissolved air. The apparatus is adapted to provide breathable air. The apparatus comprises an inlet means for extracting a quantity of water from the body of water. It further comprises a separator for separating the dissolved air from the quantity of water, thereby obtaining the breathable air. The apparatus further comprises a first outlet means for expelling the separated water back into the body of water, and a second outlet means for removing the breathable air and supplying it for breathing. The air is supplied so as to enable it to be expelled back into the body of water after it has been breathed.

Finally, here is the conclusion of the IsraCast article.

If everything goes according to plan, in a few years the new tankless breathing system will be operational and will be attached to a diver in the form of a vest that will enable him to stay underwater for a period of many hours.

Sources: Iddo Genuth, IsraCast, May 31, 2005; and various websites

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Searching within large databases has never been easy. But when it comes to physics, and especially to experiments with particle colliders, the task becomes extremely difficult. You have to look at hundreds of millions of particle collisions to isolate only a few dozens of interest. And when you realize that all these individual records are stored in data files and systems scattered all over the world, it becomes clear that the search process is a tough challenge to crack. But now, a technology known as the Word-Aligned Hybrid (WAH) compression method and developed at Lawrence Berkeley National Laboratory (BNL), is dramatically speeding up the searching process. For example, it took only 15 minutes to retrieve 80 events recorded in 2001 and hidden like needles in a haystack of information inside petabytes of data. But read more…

Here is how BNL describes how the WAH method is used.

WAH is currently used in a software package called FastBit to compress bitmap indexes. A bitmap index is a method of reducing the response time of queries involving common types of conditions in data objects, such as “state = CA” and “age >= 21.” It achieves this by storing certain pre-computed answers as bitmaps. For example, a bitmap index for “state” might have one bitmap for each state in the U.S. Because computers can manipulate bitmaps efficiently, bitmap indices are efficient in searching for interesting records in large datasets.

WAH compression makes the bitmap index optimal in terms of computational complexity. A small number of the most efficient indexing schemes have this optimality property. What makes the new technology unique is that WAH-compressed indexes significantly outperform other schemes in tests.

“In tests conducted using actual data from high-energy physics experiments, we confirmed that our FastBit software is an order of magnitude faster than the best-known bitmap indexing schemes on average,” according to John Wu, the lead developer of FastBit.

Of course, the key here was to build the compressed indexing system.

A number of specialized compression schemes have been proposed to process compressed indexes efficiently, with the best-known one called the Byte-aligned Bitmap Code (BBC).

The goal of the Berkeley Lab project was to create an indexing system that could be compressed and at the same time offers much faster searches than existing methods. To achieve this goal, the WAH compression scheme was developed. While WAH-compressed indexes are slightly larger than BBC-compressed indexes, the time needed to process a query is less, often much less.

Now, let’s look in more details at the Grid Collector, the software used to analyze the petabytes of data generated each year by the STAR (Solenoidal Tracker at RHIC) high-energy physics experiment.

First, here is a link to a paper called “The Grid Collector: Using an Event Catalog to Speedup User Analysis in Distributed Environment” (PDF format, 4 pages, 251 KB).

Then, this research work will be presented next June at the International Supercomputer Conference in Heidelberg, Germany, where it was selected as one of the three best papers.

Here is a link to the abstract of this paper named “Grid Collector: Facilitating Efficient Selective Access from Data Grids.” Below is an excerpt.

Since most analysis jobs filter out significant number of events, a considerable amount of time is wasted by reading the unwanted events. The Grid Collector removes this inefficiency by allowing users to specify more precisely what events are of interest and to read only the selected events. This speeds up most analysis jobs. In existing analysis frameworks, the responsibility of bringing files from tertiary storage to disk falls on the users. This forces most of analysis jobs to be performed at centralized computer facilities where commonly used files are kept on disks.

Finally, the researchers have filed an application for a U.S. patent which was granted on December 14, 2004 under the name “Word aligned bitmap compression method, data structure, and apparatus.” And here is a link to this patent number 6,831,575.

Sources: Lawrence Berkeley National Laboratory news release, May 16, 2005; and various websites

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Using a thin film of silver as the lens and ultraviolet (UV) light, scientists at UC Berkeley have built a superlens able to record images with a resolution of 60 nanometers and suitable for integration in today’s optical microscopes which have only a resolution of down to 400 nanometers. Scanning electron and atomic force microscopes can capture detail down to a few nanometers, but they need minutes to take an image, while this new superlens can take snapshots in a fraction of a second. In the short term, this superlens will lead to new nanoscale biomedical imaging devices. But it also can lead to other advances in nanoengineering such as higher density electronic circuitry or faster fiber optic communications systems. Read more…

Let’s start with a brief description of this achievement.

Using a thin film of silver as the lens and ultraviolet (UV) light, the researchers recorded the images of an array of nanowires and the word “NANO” onto an organic polymer at a resolution of about 60 nanometers. In comparison, current optical microscopes can only make out details down to one-tenth the diameter of a red blood cell, or about 400 nanometers.

At top (A) is the higher resolution image of the word NANO created with a silver superlens. Below that (B) is an image created during a control experiment in which the superlens is replaced by spacer layer. The averaged line width is 60 nanometers in image A with the superlens, and 321 nanometer in image B without the superlens. The scale bar in both images is 2 micrometers. (Image by Cheng Sun, UC Berkeley; legend from UC Berkeley).

Here is a link to a larger version (1,500 x 836 pixels, 214 KB).

[And here are the] detailed procedures of obtaining averaged line cross-section profiles (Color Scale 0-50nm): (A) AFM topography of NANO pattern of the recorded image; (B) Zoom-in AFM image of the letter “A”; (C) A further zoomed-in scan for sufficient digitization of individual lines (in this case each pixel measures 3.9nm) (Credit: UC Berkeley).

Here is what one of the scientists says about this superlens.

“The field of optics is involved in much of today’s technology, including imaging and photolithography, which is used to make semiconductors and integrated circuits,” said Xiang Zhang, UC Berkeley associate professor of mechanical engineering and principal investigator of the study. “Our work has a far reaching impact on the development of detailed biomedical imaging, higher density electronic circuitry and ever-faster fiber optic communications.”

The biggest advantage of optical microscopes equipped with this new superlens over scanning electron and atomic force microscopes is the speed at which it can take images.

“Optical microscopes can capture an entire frame with a single snapshot in a fraction of a second,” said Nicholas Fang, [one of Zhang's former Ph.D. students,] who is now an assistant professor of mechanical engineering at the University of Illinois at Urbana-Champaign.

“That opens up nanoscale imaging to living materials, which can help biologists better understand cell structure and function in real time, and ultimately help in the development of new drugs to treat human diseases.”

Besides using this superlens for optical imaging or high-density optoelectronics, these researchers have also long term visions — or dreams.

In the long run, this line of research could lead to even higher resolution imaging for distant objects, the researchers said. This includes more detailed views of other planets as well as of human movement through surveillance satellites.

Now, let’s go down to Earth.

The research work has been published by Science Magazine on April 22, 2005 under the title “Sub-Diffraction-Limited Optical Imaging with a Silver Superlens” (Vol. 308, Issue 5721, Pages 534-537). Here is a link (free registration required) to the abstract which is reproduced below for your convenience.

Recent theory has predicted a superlens that is capable of producing sub–diffraction-limited images. This superlens would allow the recovery of evanescent waves in an image via the excitation of surface plasmons. Using silver as a natural optical superlens, we demonstrated sub–diffraction-limited imaging with 60-nanometer half-pitch resolution, or one-sixth of the illumination wavelength. By proper design of the working wavelength and the thickness of silver that allows access to a broad spectrum of subwavelength features, we also showed that arbitrary nanostructures can be imaged with good fidelity. The optical superlens promises exciting avenues to nanoscale optical imaging and ultrasmall optoelectronic devices.

Finally, please note that the second image on this page has been extracted from the supporting online material for the article mentioned above (PDF format, 12 pages, 564 KB).

Sources: Sarah Yang, University of California at Berkeley news release, April 21, 2005; Science, Vol. 308, Issue 5721, Pages 534-537, April 22, 2005; and various websites

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You certainly know that it’s possible to alter the shape of plastics and polymers by heating them. But now, a team of American and German researchers have found a way to change plastics shape with light, according to this MIT news release. These special polymers can move to new shapes by being exposed to light of specific wavelengths. And they’ll retain this stable new shape until they’re illuminated with another source of light of a different wavelength. This discovery has many potential applications, particularly for medical applications, such as expandable strings keeping blood vessels opened during surgery. Read more…

Here is the introduction of this news release.

Picture a flower that opens when facing the sunlight. In work that mimics that sensitivity to light, an MIT engineer and his German colleagues have created the first plastics that can be deformed and temporarily fixed into shape by light.

Here is how this works.

Key to the work: “molecular switches,” or photosensitive groups that are grafted onto a permanent polymer network. The resulting photosensitive polymer film is then stretched with an external stress and illuminated with ultraviolet light of a certain wavelength. This prompts the molecular switches to crosslink, or bind one to another.

The result? When the light is switched off and the external stress released, the crosslinks remain, maintaining an elongated structure. Exposure to light of another wavelength cleaves the new bonds, allowing the material to spring back to its original shape.

“This is really a new family of materials that can change from one shape to another by having light shined on them,” said Institute Professor Robert Langer of MIT.

And what are some possible applications of these new materials?

Imagine, for example, a “string” of plastic that a doctor could thread into the body through a tiny incision. When activated by light via a fiber-optic probe, that slender string might change into a corkscrew-shaped stent for keeping blood vessels open.

The team is also looking at other medical and industrial applications, such as “paper clips that relax when you don’t need them anymore.”

This research work has been published by Nature in its April 14, 2005 isuue under the title “Light-induced shape-memory polymers.” Here is a link to the abstract and below is the text of this abstract.

Materials are said to show a shape-memory effect if they can be deformed and fixed into a temporary shape, and recover their original, permanent shape only on exposure to an external stimulus. Shape-memory polymers have received increasing attention because of their scientific and technological significance.

In principle, a thermally induced shape-memory effect can be activated by an increase in temperature (also obtained by heating on exposure to an electrical current or light illumination). Several papers have described light-induced changes in the shape of polymers and gels, such as contraction, bending or volume changes. Here we report that polymers containing cinnamic groups can be deformed and fixed into pre-determined shapes — such as (but not exclusively) elongated films and tubes, arches or spirals — by ultraviolet light illumination.

These new shapes are stable for long time periods, even when heated to 50 °C, and they can recover their original shape at ambient temperatures when exposed to ultraviolet light of a different wavelength. The ability of polymers to form different pre-determined temporary shapes and subsequently recover their original shape at ambient temperatures by remote light activation could lead to a variety of potential medical and other applications.

Finally, if the subject interests you, here are two references to previous papers about shape-memory polymers, “Biodegradable, Elastic Shape-Memory Polymers for Potential Biomedical ApplicationsScience” published by Science in May 2002 (free registration for access to the full paper) and “Shape Memory Polymers: Biodegradable Sutures,” published by Materials World in July 2002.

Sources: Elizabeth Thomson, MIT News Office, April 14, 2005; and various websites

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Physicists from several U.S. labs have clocked the transition of vanadium dioxide nanoparticles from a transparent to a reflective, mirror-like state, at less than 100 femtoseconds (a tenth of a trillionth of a second). According to this Vanderbilt University report, this effect has a size limit: “it does not occur in particles that are smaller than about 20 atoms across (10 nanometers).” This opens the door — if I can say so — to windows that are transparent at low temperatures and block out sunlight when the temperature rises. But other applications are possible, such as nanosensors which could measure the temperature at different locations within human cells, or “ultrafast” optical switches which could be used in communications and optical computing. Read more…

Let’s start with an image which probably took lots of work to its creator, René Lopez.

[Note: the transition from visible to non-visible state of Don Quixote and Sancho Panza is viewable (no punt intended!) from the VU article or directly here (Macromedia Flash format).]

Now, let’s go back to the facts as exposed by the Vanderbilt University (VU) online journal.

How this material (vanadium dioxide or VO2) can turn from a transparent insulator into a reflective metal so rapidly has physicists scratching their heads, but a collaboration among researchers at Vanderbilt, Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory has clocked the transfiguration at one-tenth of a trillionth of a second.

“The change from insulator to metal is called a phase transition,” explains Richard Haglund, a Vanderbilt physics professor. “Phase transitions in solids generally occur at the speed of sound in the material, but vanadium dioxide makes the switch 10 times faster. So far no one has succeeded in coming up with a definitive explanation for that rapid a change.”

But now, the researchers think they have one.

The researchers answered that question by detecting the appearance of a phenomenon called “surface plasmon resonance.” This is a form of electron wave that only occurs on the surfaces of metals and is responsible for the glowing colors of stained glass. Detection of this effect confirmed that vanadium dioxide can switch all the way from transparent to reflective in less than 100 femtoseconds (a tenth of a trillionth of a second).

The new Vanderbilt Institute of Nanoscale Science and Engineering (VINSE) allowed these researchers to go further and to discover that this switch effect had some size limits.

This has allowed them to verify that nanoparticles undergo the same phase transition as thin films. They also have determined that the effect has a size limit: It does not occur in particles that are smaller than about 20 atoms across (10 nanometers). The researchers have established that it is possible to raise and lower the temperature at which the insulator/metal transition takes place by as much as 35 degrees Celsius by adding small amounts of impurities.

And this temperature effect leads to new applications.

It is relatively easy to change the material’s transition temperature to body temperature (98 degrees Fahrenheit; 37 degrees Celsius) by adding precise amounts of impurities. Such doped nanoparticles would be small enough to measure the temperature at different locations within an individual cell and, when injected into the body, could pinpoint hot spots by turning into microscopic mirrors.

Of course, there will be other applications for such a fast ‘phase transition’ effect.

For example, they are exploring whether they can create an “ultrafast” optical switch by putting a layer of vanadium dioxide nanoparticles on the end of an optical fiber. Such a switch could be useful in communications and optical computing.

This research work has been explained in a paper published by Optics Letters in its March 2005 issue under the name “Photoinduced phase transition in VO2 nanocrystals: ultrafast control of surface-plasmon resonance” (Volume 30, Issue 5, 558-560). Here is the text of the abstract.

We study the ultrafast insulator-to-metal transition in nanoparticles of VO2, obtained by ion implantation and self-assembly in silica. The nonmagnetic, strongly correlated compound VO2 undergoes a reversible phase transition, which can be photoinduced on an ultrafast time scale. In the nanoparticles, prompt formation of the metallic state results in the appearance of surface-plasmon resonance. We achieve large, ultrafast enhancement of optical absorption in the near-infrared spectral region that encompasses the wavelength range for optical-fiber communications. One can further tailor the response of the nanoparticles by controlling their shape.

Sources: David F. Salisbury, in Exploration, the online journal of Vanderbilt University, April 6, 2005; and various websites

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In “Life on the Scales,” Science News recently wrote that some simple mathematical equations, known as quarter-power scaling laws, can explain the metabolic rates of living organisms. For example, “an animal’s metabolic rate appears to be proportional to mass to the 3/4 power.” And this “3/4-power law appears to hold sway from microbes to whales, creatures of sizes ranging over a mind-boggling 21 orders of magnitude.” The ecologists, physicists and chemists behind this research are now successfully applying this equation to plants, fish, full ecosystems and even biology and genetics, by adding a new key parameter: temperature. Please read this fascinating article for many more details and references. But save some time to read another long article, “Ecology’s Big, Hot Idea,” published by PLoS Biology, which states that “the way life uses energy is a unifying principle for ecology in the same way that genetics underpins evolutionary biology.” Read more…

The Science News article starts with a simple observation. Although a mouse has a shorter life than an elephant, both clock approximately the same number of heartbeats during their lives. Simply, their metabolisms are different. Now, let’s go back several decades ago.

Scientists have long known that most biological rates appear to bear a simple mathematical relationship to an animal’s size: They are proportional to the animal’s mass raised to a power that is a multiple of 1/4. These relationships are known as quarter-power scaling laws. For instance, an animal’s metabolic rate appears to be proportional to mass to the 3/4 power, and its heart rate is proportional to mass to the –1/4 power.

In subsequent decades, biologists have found that the 3/4-power law appears to hold sway from microbes to whales, creatures of sizes ranging over a mind-boggling 21 orders of magnitude.

But nobody had an explanation for this scaling law – until 1997.

The beginnings of an explanation came in 1997, when ecologist James Brown of the University of New Mexico in Albuquerque, physicist Geoffrey West of Los Alamos (N.M.) National Laboratory, and Brian Enquist, an ecologist at the University of Arizona in Tucson, described metabolic scaling in mammals and birds in terms of the geometry of their circulatory systems. It turns out, West says, that Rubner was on the right track in comparing surface area with volume, but that an animal’s metabolic rate is determined not by how efficiently it dissipates heat through its skin but by how efficiently it delivers fuel to its cells.

The idea, West says, is that a space-filling surface scales as if it were a volume, not an area. If you double each of the dimensions of your laundry machine, he observes, then the amount of linens you can fit into it scales up by 2³, not 2². Thus, an animal’s effective surface area scales as if it were a three-dimensional, not a two-dimensional, structure.

This law also can be applied to plants, fish, or even cancer growth rates — providing you add a new parameter: temperature.

In 2001, after James Gillooly, a specialist in body temperature, joined Brown at the University of New Mexico, the researchers and their collaborators presented their master equation, which incorporates the effects of size and temperature. An organism’s metabolism, they proposed, is proportional to its mass to the 3/4 power times a function in which body temperature appears in the exponent.

When the researchers filter out the effects of body temperature, most species adhere closely to quarter-power laws for a wide range of properties, including not only life span but also population growth rates. The team is now applying its master equation to more life processes — such as cancer growth rates and the amount of time animals sleep.

Now, it’s time for two key quotes [which don't appear in bold characters in the original article.]

“We’ve found that despite the incredible diversity of life, from a tomato plant to an amoeba to a salmon, once you correct for size and temperature, many of these rates and times are remarkably similar,” says Gillooly.

“Metabolic rate is, in our view, the fundamental biological rate,” Gillooly says. There is a universal biological clock, he says, “but it ticks in units of energy, not units of time.”

Then the researchers applied their master equation to ecosystems such as forests, and even to evolutionary biology, trying to answer this question: “Why do the fossil record and genetic data often give different estimates of when certain species diverged?”

When the researchers use their master equation to correct for the effects of size and temperature, the genetic estimates of divergence times — including those of rats and mice — line up well with the fossil record, says Allen, one of the paper’s coauthors.

As I wrote in the introduction, don’t miss this other paper by John Whitfield in PLoS Biology on a similar subject, “Ecology’s Big, Hot Idea.” Here are the two first paragraphs.

Life is complicated. It comes in all sorts of shapes, sizes, places, and combinations, and has evolved a dizzying variety of solutions to the problem of carrying on living. Yet look inside a cell and life takes on, if not simplicity, then at least a certain uniformity — a genetic system based around nucleic acids, for example, and a common set of chemical reactions for turning food into fuel. And looked at in broad swathes, life shows striking generalities and patterns. Every mammal’s heart will beat about one billion times in its lifetime. Both within and between species, the density of a population declines in a regular way as the size of individuals increases. And the number of species in all environments declines as you move from the equator towards the poles.

Wouldn’t it be good if there were a simple theory that used life’s shared fundamentals to explain its large-scale regularities, via its diversity of individuals? In the past few years, a team of ecologists and physicists have come up with just such a theory. At its heart is metabolism: the way life uses energy is, they claim, a unifying principle for ecology in the same way that genetics underpins evolutionary biology. They believe that energy use, in the form of metabolic rate, can be understood from the first principles of physics, and that metabolic rate can explain growth, development, population dynamics, molecular evolution, the flux of chemicals through the environment, and patterns of species diversity — to name a few.

If you don’t have enough time today, print the two articles I mentioned and read them next weekend. I promise you will not waste your time.

Sources: Erica Klarreich, Science News, Vol. 167, No. 7, p. 106, February 12, 2005; John Whitfield, PLoS Biology, Vol. 2, Issue 12, December 14, 2004

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