Monday, March 15, 2010

A CONVINCING MIMIC: SCIENTISTS REPORT OCTOPUS IMITATING FLOUNDER IN THE ATLANTIC REMARKABLE STRATEGY EVOLVED TO AVOID PREDATORS

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On the open sand plains of the Caribbean seafloor, where soft-bodied animals are routinely exposed to predators, camouflage can be key to survival. Perhaps no group of animals is quite as adept at blending in with its surroundings as cephalopods, who along with relatives the cuttlefish and squid, have evolved a unique skin system that can instantaneously change their appearance.

In the February 2010 issue of The Biological Bulletin, MBL Senior Scientist and cephalopod expert Roger Hanlon and his colleagues report the exceptional camouflage capabilities of the Atlantic longarm octopus, Macrotritopus defilippi, whose strategy for avoiding predators includes expertly disguising itself as a flounder. While Hanlon and others have documented two other species of octopuses imitating flounder in Indonesian waters, this is the first report of flounder mimicry by an Atlantic octopus, and only the fourth convincing case of mimicry for cephalopods.

Comparing still photographs and video footage from five Caribbean locations collected over the last decade, Hanlon and co-authors, MBL graduate students Anya Watson and Alexandra Barbosa, observed uncanny similarities between the small and delicate octopus and the peacock flounder, Bothus lunatus, one of the most common sand dwellers in the Caribbean. They compared not only coloration, which in each animal resembled the sandy seafloor, but swimming speed and form.

Just like flounder, the octopuses contoured their bodies to hug the wavy seafloor, tapering their arms behind them. They also swam with the same fits and starts as flounder at the same speeds. Interestingly, the octopuses mimicked flounder only when swimming, when movement would compromise their camouflage. How well the animals blended in with their background differed. The octopus showed more highly controlled and rapid skin patterning than the flounder, whose camouflage was slower and less precise.

“We were equally impressed with the remarkable camouflage of this small octopus species even when it was stationary yet entirely exposed on top of the open sand,” says Hanlon. “The apparent match in pattern, color, brightness, and even 3-dimensional skin texture was noteworthy even when compared to other changeable cephalopods. They also demonstrated an unusual form of disruptive camouflage.”

So why do Atlantic longarm octopuses choose to imitate flounder as a way to avoid the threat of predators? More study of cephalopod mimicry is needed, but a possible explanation, according to Hanlon and his team, could be that predators who could easily take a bite out of the small, soft octopus might find a rigid flatfish like the flounder too much of a mouthful and avoid them.

(Photo: R. Hanlon)

Marine Biological Laboratory

'MICRORINGS' COULD NIX WIRES FOR COMMUNICATIONS IN HOMES, OFFICES

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Purdue University researchers have developed a miniature device capable of converting ultrafast laser pulses into bursts of radio-frequency signals, a step toward making wires obsolete for communications in the homes and offices of the future.

Such an advance could enable all communications, from high-definition television broadcasts to secure computer connections, to be transmitted from a single base station, said Minghao Qi, an assistant professor of electrical and computer engineering.

"Of course, ideas about specific uses of our technology are futuristic and speculative, but we envision a single base station and everything else would be wireless," he said. "This base station would be sort of a computer by itself, perhaps a card inserted into one of the expansion slots in a central computer. The central computer would take charge of all the information processing, a single point of contact that interacts with the external world in receiving and sending information."

Ordinarily, the continuous waves of conventional radio-frequency transmissions encounter interference from stray signals reflecting off of the walls and objects inside a house or office. However, the pulsing nature of the signals produced by the new "chip-based spectral shaper" reduces the interference that normally plagues radio frequency communications, said Andrew Weiner, Purdue's Scifres Family Distinguished Professor of Electrical and Computer Engineering.

Each laser pulse lasts about 100 femtoseconds, or one-tenth of a trillionth of a second. These pulses are processed using "optical arbitrary waveform technology" pioneered by Purdue researchers led by Weiner.

Findings have appeared online in the journal Nature Photonics and were published in the February print issue of the magazine. The research is based at Purdue's Birck Nanotechnology Center in the university's Discovery Park.

"What enables this technology is that our devices generate ultrabroad bandwidth radio frequencies needed to transmit the high data rates required for high resolution displays," Weiner said.

Such a technology might eventually be developed to both receive and transmit signals.

"But initially, industry will commercialize devices that only receive signals, for 'one-way' traffic, such as television sets, projectors, monitors and printers," Qi said. "This is because the sending unit for transmitting data is currently still a little bulky. Later, if the sending unit can be integrated into the devices, we could enjoy full two-way traffic, enabling the wireless operation of things like hard-disc drives and computers."

The approach also might be used for transmitting wireless signals inside cars.

The researchers first create laser pulses with specific "shapes" that characterize the changing intensity of light from the beginning to end of each pulse. The pulses are then converted into radio frequency signals.

A key factor making the advance potentially useful is that the pulses transmit radio frequencies of up to 60 gigahertz, a frequency included in the window of the radio spectrum not reserved for military communications.

The Federal Communications Commission does not require a license to transmit signals from 57-64 gigahertz. This unlicensed band also is permitted globally, meaning systems using 60 gigahertz could be compatible worldwide.

"There is only a very limited window for civil operations, and 60 gigahertz falls within this window," Qi said.

Ordinary computer chips have difficulty transmitting electronic signals at such a rapid frequency because of "timing jitter," or the uneven timing with which transistors open and close to process information.

This uneven "clock" timing, or synchronization, of transistors does not hinder ordinary computer chips, which have a speed of about 3 gigahertz. However, for devices switching on and off at 60 gigahertz, this jitter prevents proper signal processing.

Another complication is that the digital-to-analog converters needed to convert pulsing laser light into radio frequency signals will not work at such high frequencies.

To sidestep these limitations, researchers have previously created "bulk optics" systems, which use mirrors, lenses and other optical components arranged on a vibration-dampened table several feet long to convert and transmit the pulsed signals.

However, these systems are far too large to be practical.

Now, the Purdue researchers have miniaturized the technology small enough to fit on a computer chip.

"We shrank the size of the bulk optical setup by thousands of times," Qi said.

The system is programmable so that it could be instructed to produce and transmit only certain frequencies, he said.

The researchers fabricated tiny silicon "microring resonators," devices that filter out certain frequencies and allow others to pass. A series of the microrings were combined in a programmable "spectral shaper" 100 microns wide, or about the width of a human hair. Each of the microrings is about 10 microns in diameter.

The microring filter can be tuned by heating the rings, which causes them to change so that they filter different frequencies. The research is funded by the National Science Foundation, the Defense Threat Reduction Agency, and the National Security Science and Engineering Faculty Fellowship program from the Office of the Secretary of Defense.

Purdue filed a provisional patent in January for the technology, which is at least five years away from being ready for commercialization, Qi said.

(Photo: Purdue University, Michael Esposito)

Purdue University

RESEARCHERS FIND WEAKNESS IN COMMON DIGITAL SECURITY SYSTEM

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The most common digital security technique used to protect both media copyright and Internet communications has a major weakness, University of Michigan computer scientists have discovered.

RSA authentication is a popular encryption method used in media players, laptop computers, smartphones, servers and other devices. Retailers and banks also depend on it to ensure the safety of their customers' information online.

The scientists found they could foil the security system by varying the voltage supply to the holder of the "private key," which would be the consumer's device in the case of copy protection and the retailer or bank in the case of Internet communication. It is highly unlikely that a hacker could use this approach on a large institution, the researchers say. These findings would be more likely to concern media companies and mobile device manufacturers, as well as those who use them.

Andrea Pellegrini, a doctoral student in the Department of Electrical Engineering and Computer Science, presented a paper on the research at the upcoming Design, Automation and Test in Europe (DATE) conference in Dresden on March 10.

"The RSA algorithm gives security under the assumption that as long as the private key is private, you can't break in unless you guess it. We've shown that that's not true," said Valeria Bertacco, an associate professor in the Department of Electrical Engineering and Computer Science.

These private keys contain more than 1,000 digits of binary code. To guess a number that large would take longer than the age of the universe, Pellegrini said. Using their voltage tweaking scheme, the U-M researchers were able to extract the private key in approximately 100 hours.

They carefully manipulated the voltage with an inexpensive device built for this purpose. Varying the electric current essentially stresses out the computer and causes it to make small mistakes in its communications with other clients. These faults reveal small pieces of the private key. Once the researchers caused enough faults, they were able to reconstruct the key offline.

This type of attack doesn't damage the device, so no tamper evidence is left.

"RSA authentication is so popular because it was thought to be so secure," said Todd Austin, a professor in the Department of Electrical Engineering and Computer Science. "Our work redefines the level of security it offers. It lowers the safety assurance by a significant amount."

Although this paper only discusses the problem, the professors say they've identified a solution. It's a common cryptographic technique called "salting" that changes the order of the digits in a random way every time the key is requested.

"We've demonstrated that a fault-based attack on the RSA algorithm is possible," Austin said. "Hopefully, this will cause manufacturers to make a few small changes to their implementation of the algorithm. RSA is a good algorithm and I think, ultimately, it will survive this type of attack."

University of Michigan

ATMOSPHERIC NANOPARTICLES IMPACT HEALTH, WEATHER PROF SAYS

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Nanoparticles are atmospheric materials so small that they can’t be seen with the naked eye, but they can very visibly affect both weather patterns and human health all over the world – and not in a good way, according to a study by a team of researchers at Texas A&M University.

Researchers Lin Wang, Renyi Zhang, Alexei Khalizov, Jun Zheng, Wen Xu, Yan Ma and Vinita Lal in the Departments of Atmospheric Sciences and Chemistry say that nanoparticles appear to be growing in many parts of the world, but how they do so remains a mystery.

Their work is published in the current issue of “Nature Geoscience” and was funded by the National Science Foundation and The Welch Foundation.

The team looked at how nanoparticles are formed and their relationship with certain organic vapors responsible for additional growth.

“This is one of the most poorly understood of all atmospheric processes,” Zhang says. “But we found that certain types of organics tend to grow very rapidly. When this happens, they scatter light back into space, and that definitely has a cooling effect – sort of a reverse ‘greenhouse effect.’ It can alter Earth’s weather patterns and it also tends to have a negative effect on human health.”

Persons with breathing problems, such as those who suffer from asthma, emphysema or other lung ailments, can be at risk, he notes.

Zhang says the team used new methods of measuring nanoparticles and formed new models to determine their impact on atmospheric conditions.

“These changes on our weather systems appear to be the most dramatic consequences of these nanoparticles,” he adds.

“Once these form, they can change cloud formations, which in turn can affect weather all over the world, so this can become a global problem to deal with. We’re trying to get a better understanding of these particles work and grow.

“They can form near areas that have petrochemical plants, such as Houston, which also has high amounts of aerosols from traffic emissions and other numerous factories. But we’re still trying to learn how they form and interact with the atmosphere.”

Many types of trees and plants also contribute to the formation of nanoparticles, which are natural processes, Zhang says, and certain forms of organic materials can also speed up the development of the particles. But all of these ultimately affect the atmosphere, and very often, cloud formation, where the aerosols scatter light and radiation back into space and provide the “seeds” of cloud droplets and development.

“These nanoparticles are very small – about one million times smaller than a typical raindrop,” Zhang says. “But what they do can have a huge effect on our weather.”

(Photo: TAMU)

Texas A&M University

ENGINEERING TEAM DEVELOPING HELICOPTER THAT WOULD INVESTIGATE NUCLEAR DISASTERS

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Students at Virginia Tech's Unmanned Systems Laboratory are perfecting an autonomous helicopter they hope will never be used for its intended purpose. Roughly six feet long and weighing 200 pounds, the re-engineered aircraft is designed to fly into American cities blasted by a nuclear weapon or dirty bomb.

The helicopter's main mission would be to assist military investigators in the unthinkable: Enter an American city after a nuclear attack in order to detect radiation levels, map and photograph damage.

"It's for a worst-case scenario," said project leader Kevin Kochersberger, a research associate professor of mechanical engineering and director of the Virginia Tech Unmanned Systems Laboratory (http://www.me.vt.edu/unmanned/index.html). His team consists of several graduate and undergraduate students from the mechanical engineering (http://www.me.vt.edu/) and electrical and computer engineering (http://www.ece.vt.edu/) departments.

Kochersberger and his team re-engineered a remote-controlled Yamaha-built Unmanned Aerial Vehicle RMAX helicopter to fly in fully autonomous mode. They also created flight control software algorithms that will direct the helicopter to radioactive sources on its own accord. To carry out various missions, the researchers outfitted the helicopter with various "plug-and-play payloads" as the vehicle's weight capacity is limited. The payloads are easily loadable and unloadable boxes that fit snugly under the helicopter's main body, carrying devices that would detect radiation levels in the atmosphere and on the ground, and take video and still images of damage. Flight control software would allow the mission to be changed mid-flight.

One payload is unique: A miniature tray-like robot on treads that can be launched via a tether wire from the helicopter to collect evidence. The helicopter would hover over the robot, and pull it back via the wire. A student team is building this robot, which will boast not only "chunk" sampling capability, but also a miniature vacuum which could suck up dust and dirt.

The robot is expected to easily maneuver any terrain, including expected bomb craters, as part of its investigation, said Michael Rose, a graduate student in mechanical engineering, from Gilroy, Calif. The team plans to make the robot water proof, in the event that it comes across water – busted water mains, lakes, rain puddles, etc. "The electronics must be protected from the harmful elements," Rose said.

The group also designed a downward-looking stereo camera system mounted to the helicopter, to image affected areas. The cameras would allow for computerized 3-D terrain mapping of affected areas, an absolute necessity to understand the characteristics of the blast. It is expected that the helicopter will have night vision capabilities, and enhanced imaging technologies that improve vision through smoke and fog as the project progresses, Kochersberger said.

The project, already funded at $735,000 with an additional $650,000 allocated for 2010, is overseen by the U.S. Defense Threat Reduction Agency and spearheaded by the Department of Energy's Savannah River National Laboratory. Plans call for the helicopters to be mission-ready in three years. Department of Defense personnel already have visited Blacksburg to watch a demonstration as the craft zeroed in on a small, planted radioactive source at Kentland Farm, several miles from the Virginia Tech campus. More testing is underway, with another DoD demonstration planned for 2010 in Savannah, Ga.

(Photo: Virginia Tech)

Virginia Polytechnic Institute and State University

BACTERIAL BALANCE THAT KEEPS US HEALTHY

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The thousands of bacteria, fungi and other microbes that live in our gut are essential contributors to our good health. They break down toxins, manufacture some vitamins and essential amino acids, and form a barrier against invaders. A study published in Nature shows that, at 3.3 million, microbial genes in our gut outnumber previous estimates for the whole of the human body.

Scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, working within the European project MetaHIT and in collaboration with colleagues at the Beijing Genomics Institute at Shenzhen, China, established a reference gene set for the human gut microbiome – a catalogue of the microbe genes present in the human gut. Their work proves that high-throughput techniques can be used to sequence environmental samples, and brings us closer to an understanding of how to maintain the microbial balance that keeps us healthy.

“Knowing which combination of genes is necessary for the right balance of microbes to thrive within our gut may allow us to use stool samples, which are non-invasive, as a measure of health,” says Peer Bork, whose group at EMBL took part in the analysis. “One day, we may even be able to treat certain health problems simply by eating a yoghurt with the right bacteria in it.”

This catalogue of the microbial genes harboured by the human gut will also be useful as a reference for future studies aiming to investigate the connections between bacterial genetic make-up and particular diseases or aspects of people’s lifestyles, such as diet.

To gain a comprehensive picture of the microbial genes present in the human gut, Bork and colleagues turned to the emerging field of metagenomics, in which researchers take samples from the environment they wish to study and sequence all the genetic material contained therein. They were the first to employ a high-throughput method called Illumina sequencing to metagenomics, dispelling previous doubts over the feasibility of using this method for such studies.

From a bacterium’s point of view, the human gut is not the best place to set up home, with low pH and little oxygen or light. Thus, bacteria have had to evolve means of surviving in this challenging environment, which this study now begins to unveil. The scientists identified the genes that each individual bacterium needs to survive in the human gut, as well as those that have to be present for the community to thrive, but not necessarily in all individuals, since if one species produces a necessary compound, others may not have to. This could explain another of the scientists’ findings, namely that the gut microbiomes of individual humans are more similar than previously thought: there appears to be a common set of genes which are present in different humans, probably because they ensure that crucial functions are carried out. In the future, the scientists would like to investigate whether the same or different species of bacteria contribute those genes in different humans.

European Molecular Biology Laboratory

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