Snails' Complex Muscle Movements, Rather Than Mucous, Key to Locomotion

The main aim of this study, carried out in collaboration with the University of California at San Diego (UCSD) and Stanford University (both in the US) is to characterize some aspects of gastropod (snails and slugs) locomotion to basically respond to one question: To what extent do they depend on the physical properties of their mucus to propel themselves forward? This question is fundamental when applying the studied mechanism to the construction of biomimetic robots."The aim is for the robot to be able to propel itself in any fluid mucus without having to carry its own reserve of mucus along," explained one of the authors of the research study, Javier Rodríguez, Professor at the UC3M Department of Thermal and Fluids Engineering."Bear in mind," he stated,"that snail mucus has a very particular behaviour because it is a specific type of fluid with complex physical characteristics called non-Newtonian fluid."

Until now, it was known that snails and slugs move by propagating their body in a series of muscular wave motions to advance from their tail to their head, but the importance of their mucus in this process was not known. The conclusion obtained by these scientists is that this fluid's properties are not essential for propulsion."Without a doubt, it could have other uses, such as climbing walls, moving upside down, or preserving moisture in the body when on a dry surface, but if we want to construct a robot that emulates a snail, the latter could move over fluid mucus with ordinary properties" pointed out Professor Rodríguez, who has recently published an article on this matter, together with his colleagues from the North American universities, in the scientific review,Journal of Experimental Biology.

To carry out this study, the researchers have characterized the propagation of these muscular waves which occur along the body of gastropods. For this purpose, they place the snails and slugs so that they move on transparent surfaces, illuminating their undersides in different ways so as to record images through digital cameras, subsequently analyzing this data by computer."The ways to illuminate the body vary depending on what is being measured," stated María Vázquez, research fellow from the UC3M Fluid Mechanics Group where she has collaborated in experiments carried out in Spain and in the US."For example," she explained further,"to measure the speed of the wave, we placed a light on the underneath part of the snail, while to measure the vertical deformation of the body we used a low power flat laser (so as not to harm the animal) projected at a given angle." Together, all of these measures have allowed the 3D reconstruction of the snail's underside during propulsion.

Very diverse applications

The most surprising thing about snail movement is summed up very well in a phrase from a biology professor from Stanford University, Mark W. Denny, written in the 1980's:"How can an animal with just one leg walk on glue?" And the mucus is highly adhesive, which offers some advantages such as walking on walls and moving on the ceiling. Furthermore, as anyone who has ever held a snail in their hand can testify, when snails move, they do not use force over specific points, as animals with legs do, but rather they distribute a relatively low force over a relatively large area."What also happens," Professor Rodríguez pointed out,"is that it is difficult to move over glue without exerting quite a bit of force while dragging fluid along." Snails, after millions of years of evolution, have succeeded in being able to move on a highly adhesive surface, avoiding these inconveniences"which is without a doubt of interest and worthy of study," he added

This type of research can help in the design of biomimetic robots that carry out functions which conventional devices cannot do. Some Japanese researchers, for example, propose using the snail propulsion mechanism to move an endoscope though a human body (the trachea, intestines, etc), taking advantage of the mucus film that usually covers these ducts."This mechanism," Javier Rodríguez remarked,"generates a smooth distribution of force instead of supporting itself in concrete points, which would reduce the irritation caused by the movement of an endoscope, in this case."

At the moment, the results published by the UC3M, UCSD and Stanford scientists only deal with the experimental part of study carried out, although they are working on a second article that includes a simple theoretical model which explains these animals' movement. The preliminary results were presented last November at the Annual Conference of The American Physical Society. In addition, these researchers are interested in extending their analysis to situations in which the animal moves up slopes of varying angles.

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NASA Makes Use of Historic Test Site for New Robotic Lander Prototype Tests

This initial test phase, or strapdown testing, allows the engineering team to fully check out the integrated lander prototype before moving to more complex free flight tests. The team secures, or straps down, the prototype during hot fire tests to validate the propulsion system's response to the flight guidance, navigation and control algorithms and flight software prior to autonomous free flight testing.

"Moving the robotic lander tests to the Redstone Test Center facility is a good example of intergovernmental collaboration at its best," said Larry Hill, Robotic Lunar Lander Development Project Manager Test Director, at the Marshall Center."Engineers and

technicians from NASA, the Army and our Huntsville-based support contractor, Teledyne Brown Engineering, have worked tirelessly over the last month to modify the historic test facility formerly used for missile testing to accommodate NASA's lander test in record time, saving NASA time and money."

"Our team has been on a record paced design and development schedule to deliver the robotic lander prototype to the test site," said Julie Bassler, Robotic Lunar Lander Development Project Manager."We have succeeded in designing, building and testing this new lander prototype in a short 17 months with an in-house NASA Marshall team in collaboration with the our partners" -- Johns Hopkins Applied Physics Laboratory of Laurel, Md., and the Von Braun Center for Science and Innovation in Huntsville.

The flight test program includes three phases of testing culminating in free flight testing for periods up to sixty seconds scheduled for summer 2011. The prototype provides a platform to develop and test algorithms, sensors, avionics, software, landing legs, and integrated system elements to support autonomous landings on airless bodies, where aero-braking and parachutes are not options. The test program furthers NASA's capability to conduct science and exploration activities on airless bodies in the solar system.

Development and integration of the lander prototype is a cooperative endeavor led by the Robotic Lunar Lander Development Project at the Marshall Center, Johns Hopkins Applied Physics Laboratory and the Von Braun Center for Science and Innovation, which includes the Science Applications International Corporation, Dynetics Corp., Teledyne Brown Engineering Inc., and Millennium Engineering and Integration Company, all of Huntsville.

The project is partnered with the U.S. Army's Test and Evaluation Command's test center located at Redstone Arsenal. Redstone Test Center is one of six centers under the U.S. Army Test and Evaluation Command and has been a leading test facility for defense systems since the 1950's. Utilizing an historic test site at the Arsenal, the project is leveraging the Redstone Test Center's advanced capability for propulsion testing.

For more photos of the hardware visit:http://www.nasa.gov/roboticlander

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NASA Readies for World's Largest Can Crusher Test

It's similar to what a team of NASA engineers will do to an immense aluminum-lithium rocket fuel tank in late March; their hope is to use data from the test to generate new"shell-buckling design factors" that will enable light-weight, safe and sturdy"skins" for future launch vehicles.

Testing for this innovative study is under way at NASA's Marshall Space Flight Center in Huntsville, Ala., where engineers are supporting the test led by the NASA Engineering and Safety Center, or NESC, based at NASA's Langley Research Center in Hampton, Va.

The aerospace industry's shell buckling knockdown factors are a complex set of engineering data that dates back to Apollo-era studies of rocket structures -- well before modern composite materials, manufacturing processes and advanced computer modeling. The hope is for the new test data to update essential calculations that are typically a significant cost, performance, and safety driver in designing large structures like the main fuel tank of a future heavy-lift launch vehicle.

The large-scale test follows a series of smaller scale tests, all aimed at reducing the time and money spent designing and testing future rockets. And by incorporating more modern, lighter high-tech materials into the design and manufacturing process, rockets will save weight and carry more payload.

This week, technicians moved a 27.5-foot-diameter and 20-foot-tall space shuttle external tank barrel-shaped test article into place at Marshall's Engineering Test Laboratory. Once installed, the section will be sandwiched between two massive loading rings that will press down with almost one-million pounds of force on the central cylindrical test article forcing it to buckle.

"Spacecraft structures, especially fuel tanks, are designed to be as thin as possible, as every pound of vehicle structure sacrifices valuable payload weight and can dramatically increase the cost of flying a rocket," said Mark Hilburger, a senior research engineer in the Structural Mechanics and Concepts Branch at Langley and the principal investigator of the NESC's Shell Buckling Knockdown Factor project."Looking toward future heavy-lifters, our goal is to provide designers greater confidence in how buckling happens in structures so we can develop lighter-weight tanks."

Research to date suggests a potential weight savings of as much as 20 percent.

Leading up to the big crush in late March, the shell buckling team has previously tested four, 8-foot-diameter aluminum-lithium cylinders to failure. In preparation for the upcoming test, hundreds of sensors have been placed on the barrel section to measure strain, local deformations and displacement. In addition, advanced optical measurement techniques will be used to monitor tiny deformations over the entire outer surface of the test article.

"This unique test rig was essential to developing the lightweight space shuttle external tank that is flying today. Our sophisticated testing capability is back in action to better understand design factors for next-generation metallic launch vehicle structures," said Mike Roberts, an engineer in Marshall's Structural Strength Test branch and the center lead for this test activity."Months of preparation for the facility, test article, high-speed cameras and data systems are all in place and ready to support this major test."

The Shell Buckling Knockdown Factor Project is led and funded by the NESC; Marshall is responsible for the test including the engineering, the equipment design, the hardware facilities and safety assurance. Lockheed Martin Space Systems Company fabricated the test article at Marshall's Advance Weld Process Development Facility using state of the art welding and inspection techniques.

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Method Developed to Match Police Sketch, Mug Shot: Algorithms and Software Will Match Sketches With Mugshots in Police Databases

A team led by MSU University Distinguished Professor of Computer Science and Engineering Anil Jain and doctoral student Brendan Klare has developed a set of algorithms and created software that will automatically match hand-drawn facial sketches to mug shots that are stored in law enforcement databases.

Once in use, Klare said, the implications are huge.

"We're dealing with the worst of the worst here," he said."Police sketch artists aren't called in because someone stole a pack of gum. A lot of time is spent generating these facial sketches so it only makes sense that they are matched with the available technology to catch these criminals."

Typically, artists' sketches are drawn by artists from information obtained from a witness. Unfortunately, Klare said,"often the facial sketch is not an accurate depiction of what the person looks like."

There also are few commercial software programs available that produce sketches based on a witness' description. Those programs, however, tend to be less accurate than sketches drawn by a trained forensic artist.

The MSU project is being conducted in the Pattern Recognition and Image Processing lab in the Department of Computer Science and Engineering. It is the first large-scale experiment matching operational forensic sketches with photographs and, so far, results have been promising.

"We improved significantly on one of the top commercial face-recognition systems," Klare said."Using a database of more than 10,000 mug shot photos, 45 percent of the time we had the correct person."

All of the sketches used were from real crimes where the criminal was later identified.

"We don't match them pixel by pixel," said Jain, director of the PRIP lab."We match them up by finding high-level features from both the sketch and the photo; features such as the structural distribution and the shape of the eyes, nose and chin."

This project and its results appear in the March 2011 issue of the journalIEEE Transactions on Pattern Analysis and Machine Intelligence.

The MSU team plans to field test the system in about a year.

The sketches used in this research were provided by forensic artists Lois Gibson and Karen Taylor, and forensic sketch artists working for the Michigan State Police.

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New Technique for Improving Robot Navigation Systems

An autonomous mobile robot is a robot that is able to navigate its environment without colliding or getting lost. Unmanned robots are also able to recover from spatial disorientation. Conducted by Sergio Guadarrama, researcher of the European Centre for Soft Computing, and Antonio Ruiz, assistant professor at the Universidad Politécnica de Madrid's Facultad de Informática, and published in the Information Sciences journal, the research focuses on map building. Map building is one of the skills related to autonomous navigation, where a robot is required to explore an unknown environment (enclosure, plant, buildings, etc.) and draw up a map of the environment. Before it can do this, the robot has to use its sensors to perceive obstacles.

The main sensor types used for autonomous navigation are vision and range sensors. Although vision sensors can capture much more information from the environment, this research used range, specifically ultrasonic, sensors, which are less accurate, to demonstrate that the model builds accurate maps from few and imprecise input data.

Once it has captured the ranges, the robot has to map these distances to obstacles on the map. Point clouds are used to draw the map, as the imprecision of the range data rules out the use of straight lines or even isolated points. Even so, the resulting map is by no means an architectural blueprint of the site, because not even the robot's location is precisely known, and there is no guarantee that each point cloud is correctly positioned. In actual fact, one and the same obstacle can be viewed properly from one robot position, but not from another. This can produce contradictory information -obstacle and no obstacle- about the same area of the map under construction. Which of the two interpretations is correct?

Exploring unknown spaces

The solution is based on linguistic descriptions of the antonyms"vacant" and"occupied" and inspired by computing with words and the computational theory of perceptions, two theories proposed by L.A. Zadeh of the University of California at Berkeley. Whereas other published research views obstacles and empty spaces as complementary concepts, this research assumes that, rather than being complements, obstacles and vacant spaces are a pair of opposites.

For example, we can infer that an occupied space is not vacant, but we cannot infer that an unoccupied space is empty. This space could be unknown or ambiguous, because the robot has limited information about its environment. Also the contradictions between"vacant" and"occupied" are also explicitly represented.

This way, the robot is able to make a distinction between two types of unknown spaces: spaces that are unknown because information is contradictory and spaces that are unknown because they are unexplored. This would lead the robot to navigate with caution through the contradictory spaces and explore the unexplored spaces. The map is constructed using linguistic rules, such as"If the measured distance is short, then assign a high confidence level to the measurement" or"If an obstacle has been seen several times, then increase the confidence in its presence," where"short,""high" and"several" are fuzzy sets, subject to fuzzy sets theory. Contradictions are resolved by a greater reliance on shorter ranges and combining multiple measures.

Compared with the results of other methods, the outcomes show that the maps built using this technique better capture the shape of walls and open spaces, and contain fewer errors from incorrect sensor data. This opens opportunities for improving the current autonomous navigation systems for robots.

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New Kind of Optical Fiber Developed: Made With a Core of Zinc Selenide

The team's research will be published in the journalAdvanced Materials.

"It has become almost a cliche to say that optical fibers are the cornerstone of the modern information age," said Badding."These long, thin fibers, which are three times as thick as a human hair, can transmit over a terabyte -- the equivalent of 250 DVDs -- of information per second. Still, there always are ways to improve on existing technology." Badding explained that optical-fiber technology always has been limited by the use of a glass core."Glass has a haphazard arrangement of atoms," Badding said."In contrast, a crystalline substance like zinc selenide is highly ordered. That order allows light to be transported over longer wavelengths, specifically those in the mid-infrared."

Unlike silica glass, which traditionally is used in optical fibers, zinc selenide is a compound semiconductor."We've known for a long time that zinc selenide is a useful compound, capable of manipulating light in ways that silica can't," Badding said."The trick was to get this compound into a fiber structure, something that had never been done before." Using an innovative high-pressure chemical-deposition technique developed by Justin Sparks, a graduate student in the Department of Chemistry, Badding and his team deposited zinc selenide waveguiding cores inside of silica glass capillaries to form the new class of optical fibers."The high-pressure deposition is unique in allowing formation of such long, thin, zinc selenide fiber cores in a very confined space," Badding said.

The scientists found that the optical fibers made of zinc selenide could be useful in two ways. First, they observed that the new fibers were more efficient at converting light from one color to another."When traditional optical fibers are used for signs, displays, and art, it's not always possible to get the colors you want," Badding explained."Zinc selenide, using a process called nonlinear frequency conversion, is more capable of changing colors."

Second, as Badding and his team expected, they found that the new class of fiber provided more versatility not just in the visible spectrum, but also in the infrared -- electromagnetic radiation with wavelengths longer than those of visible light. Existing optical-fiber technology is inefficient at transmitting infrared light. However, the zinc selenide optical fibers that Badding's team developed are able to transmit the longer wavelengths of infrared light."Exploiting these wavelengths is exciting because it represents a step toward making fibers that can serve as infrared lasers," Badding explained."For example, the military currently uses laser-radar technology that can handle the near-infrared, or 2 to 2.5-micron range. A device capable of handling the mid-infrared, or over 5-micron range would be more accurate. The fibers we created can transmit wavelengths of up to 15 microns."

Badding also explained that the detection of pollutants and environmental toxins could be yet another application of better laser-radar technology capable of interacting with light of longer wavelengths."Different molecules absorb light of different wavelengths; for example, water absorbs, or stops, light at the wavelengths of 2.6 microns," Badding said."But the molecules of certain pollutants or other toxic substances may absorb light of much longer wavelengths. If we can transport light over longer wavelengths through the atmosphere, we can see what substances are out there much more clearly." In addition, Badding mentioned that zinc selenide optical fibers also may open new avenues of research that could improve laser-assisted surgical techniques, such as corrective eye surgery.

In addition to Badding and Sparks, other researchers who contributed to this study include Rongrui He of Penn State's Department of Chemistry and the Materials Research Institute; Mahesh Krishnamurthi and Venkatraman Gopalan of Penn State's Department of Materials Science and Engineering and the Materials Research Institute; and Pier J.A. Sazio, Anna C. Peacock, and Noel Healy of the Optoelectronics Research Centre at the University of Southampton. Support for this research was provided by the Engineering and Physical Sciences Research Council, the National Science Foundation, and the Penn State University Materials Research Science and Engineering Center.

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Silk Moth's Antenna Inspires New Nanotech Tool With Applications in Alzheimer's Research

A paper on the work is newly published online inNature Nanotechnology. This project is headed by Michael Mayer, an associate professor in the U-M departments of Biomedical Engineering and Chemical Engineering. Also collaborating are Jerry Yang, an associate professor at the University of California, San Diego and Jiali Li, an associate professor at the University of Arkansas.

Nanopores -- essentially holes drilled in a silicon chip -- are miniscule measurement devices that enable the study of single molecules or proteins. Even today's best nanopores clog easily, so the technology hasn't been widely adopted in the lab. Improved versions are expected to be major boons for faster, cheaper DNA sequencing and protein analysis.

The team engineered an oily coating that traps and smoothly transports molecules of interest through nanopores. The coating also allows researchers to adjust the size of the pore with close-to-atomic precision.

"What this gives us is an improved tool to characterize biomolecules," Mayer said."It allows us to gain understanding about their size, charge, shape, concentration and the speed at which they assemble. This could help us possibly diagnose and understand what is going wrong in a category of neurodegenerative disease that includes Parkinson's, Huntington's and Alzheimer's."

Mayer's"fluid lipid bilayer" resembles a coating on the male silk moth's antenna that helps it smell nearby female moths. The coating catches pheromone molecules in the air and carries them through nanotunnels in the exoskeleton to nerve cells that send a message to the bug's brain.

"These pheromones are lipophilic. They like to bind to lipids, or fat-like materials. So they get trapped and concentrated on the surface of this lipid layer in the silk moth. The layer greases the movement of the pheromones to the place where they need to be. Our new coating serves the same purpose," Mayer said.

One of Mayer's main research tracks is to study proteins called amyloid-beta peptides that are thought to coagulate into fibers that affect the brain in Alzheimer's. He is interested in studying the size and shape of these fibers and how they form.

"Existing techniques don't allow you to monitor the process very well. We wanted to see the clumping of these peptides using nanopores, but every time we tried it, the pores clogged up," Mayer said."Then we made this coating, and now our idea works."

To use nanopores in experiments, researchers position the pore-pricked chip between two chambers of saltwater. They drop the molecules of interest into one of the chambers and send an electric current through the pore. As each molecule or protein passes through the pore, it changes the pore's electrical resistance. The amount of change observed tells the researchers valuable information about the molecule's size, electrical charge and shape.

Due to their small footprint and low power requirements, nanopores could also be used to detect biological warfare agents.

A research highlight on this work will appear in an upcoming edition of Nature. The paper is titled"Controlling protein translocation through nanopores with bio-inspired fluid walls."

This research is funded by the National Science Foundation, the National Institutes of Health, the Alzheimer's Disease Research Center, the Alzheimer's Association and the National Human Genome Research Institute. The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.

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