Engineers at Duke University believe that the results of feasibility studies conducted in their laboratory represent the first concrete steps toward achieving this space age vision of the future. Also, on a more immediate level, the technology developed by the engineers could make certain contemporary medical procedures safer for patients, they said.

For their experiments, the engineers started with a rudimentary tabletop robot whose “eyes” used a novel 3-D ultrasound technology developed in the Duke laboratories. An artificial intelligence program served as the robot’s “brain” by taking real-time 3-D information, processing it, and giving the robot specific commands to perform.

“In a number of tasks, the computer was able to direct the robot’s actions,” said Stephen Smith, director of the Duke University Ultrasound Transducer Group and senior member of the research team. “We believe that this is the first proof-of-concept for this approach. Given that we achieved these early results with a rudimentary robot and a basic artificial intelligence program, the technology will advance to the point where robots — without the guidance of the doctor — can someday operate on people.”

The results of a series of experiments on the robot system directing catheters inside synthetic blood vessels was published online in the journal IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. A second study, published in April in the journal Ultrasonic Imaging, demonstrated that the autonomous robot system could successfully perform a simulated needle biopsy.

Advances in ultrasound technology have made these latest experiments possible, the researchers said, by generating detailed, 3-D moving images in real-time.

The Duke laboratory has a long track record of modifying traditional 2-D ultrasound — like that used to image babies in utero — into the more advanced 3-D scans. After inventing the technique in 1991, the team also has shown its utility in developing specialized catheters and endoscopes for real-time imaging of blood vessels in the heart and brain.

In the latest experiment, the robot successfully performed its main task: directing a needle on the end of the robotic arm to touch the tip of another needle within a blood vessel graft. The robot’s needle was guided by a tiny 3-D ultrasound transducer, the “wand” that collects the 3-D images, attached to a catheter commonly used in angioplasty procedures.

“The robot was able to accurately direct needle probes to target needles based on the information sent by the catheter transducer,” said John Whitman, a senior engineering student in Smith’s laboratory and first author on both papers. “The ability of the robot to guide a probe within a vascular graft is a first step toward further testing the system in animal models.”

While the research will continue to refine the ability of robots to perform independent procedures, the new technology could also have more direct and immediate applications.

“Currently, cardiologists doing catheter-based procedures use fluoroscopy, which employs radiation, to guide their actions,” Smith said. “Putting a 3-D ultrasound transducer on the end of the catheter could provide clearer images to the physician and greatly reduce the need for patients to be exposed to radiation.”

In the earlier experiments, the tabletop robot arm successfully touched a needle on the arm to another needle in a water bath. Then it performed a simulated biopsy of a cyst, fashioned out of a liquid-filled balloon in a medium designed to simulate tissue.

“These experiments demonstrated the feasibility of autonomous robots accomplishing simulated tasks under the guidance of 3-D ultrasound, and we believe that it warrants additional study,” Whitman said.

The researchers said that adding this 3-D capability to more powerful and sophisticated surgical robots already in use at many hospitals could hasten the development of autonomous robots that could perform complex procedures on humans.

[Richard Merritt @ Duke University]

What’s more, car owners are predicted to cut back on driving in order to save money. Together, these changes in consumer behaviour could make an important dent in the US contribution to global warming, reducing annual carbon dioxide emissions by tens of millions of tonnes per year. The impact will be dramatic, says Chris Knittel, an economist at the University of California, Davis, who was involved in one of the studies.

The changes are being driven by record fuel prices in the US, where, at the end of April, the average price of gasoline stood at $3.65 per gallon, 20 percent more than in January and treble the price of a decade ago. Until recently, these increases did not seem to be having a consistent effect on the car market and fuel use. Though sales of SUVs in the US have been falling over the past few years, this decline has come on the back of years of rapid growth, and overall gasoline consumption has been increasing every year since 1991.

That could be about to change. Knittel and colleagues looked at data on 1.4 million car purchases over the past 10 years, comparing sales patterns with gas prices. They found that sales of the least fuel-efficient cars, such as SUVs and pick-up trucks, fell by 13 percent for every $1 per gallon increase in the price of gasoline. The biggest SUVs suffered the most, with sales dropping by over 25 percent for every dollar by which the gas price rose. And for every $1 hike in gas prices there was a corresponding 17 percent sales boost for the most efficient vehicles, such as compact cars and hybrids. Knittel estimates that over about a decade, such changes in buying habits could cut the amount of gasoline used by US drivers by around 7 percent for every $1 increase in its price.

Knittel’s findings, presented last month at the University of California Energy Institute in Berkeley, are in broad agreement with those of economist Kenneth Small of the University of California, Irvine. Small looked at data on US fuel consumption and prices over the past 40 years, and projected last year that the recent doubling in fuel prices would quickly lead to a 4 percent drop in the total mileage covered on the roads. In the longer term, as drivers continue to react to rising prices, he projects the size of the reduction will grow to around 20 percent (The Energy Journal, vol 28, p 25).

This would lead to a substantial reduction in carbon emissions. Small says that a $1 per gallon rise in gasoline prices, roughly that seen over the past two years, will result in motorists using 14 percent less fuel in the long term. That would avoid the release of some tens of millions of tonnes of CO2 per year, equivalent to roughly 2 percent of the country’s greenhouse-gas emissions for 2006. That is a hugely significant drop, close to the level of cuts that some nations are required to make under the Kyoto protocol.

Small’s prediction comes with major caveats, however. Gasoline prices are not expected to return to the lows of a decade ago, but could fall by 10 or 20 percent in coming years. And any US economic recovery will boost fuel consumption, partly through raising incomes, which would dilute the pressure on motorists to drive less. So while expensive fuel will rein in consumption, Small and other economists question whether this will be enough to cause an overall fall in emissions from cars.

It is also possible that politics will intervene before any of these effects has a chance to kick in. Presidential hopefuls John McCain and Hillary Clinton have reacted to consumer protests over soaring fuel prices by declaring that they would suspend federal gasoline taxes. “It’s a fantastically stupid idea,” says Roberton Williams, an economist at the University of Texas at Austin.

“But people don’t like high gas taxes, so it’s popular.”

[Claire Bowles @ New Scientist]

Among the most important and complex molecules in the human body, sugars control not just metabolism but also how cells communicate with one another. Graduating senior Jeffery Martin has put his basic knowledge of sugars to exceptional use by creating a lab-on-a-chip device that builds complex, highly specialized sugar molecules, mimicking one of the most important cellular structures in the human body — the Golgi Apparatus.

“Almost completely independently he has been able to come closer than researchers with decades more experience to creating an artificial Golgi,” said Robert Linhardt, the Ann and John H. Broadbent Jr. ‘59 Senior Constellation Professor of Biocatalysis and Metabolic Engineering at Rensselaer and Martin’s adviser. “He saw a problem in the drug discovery process and almost instantly devised a way to solve it.”

Cells build sugars in a cellular organelle known as the Golgi Apparatus. Under a microscope, the Golgi looks similar to a stack of pancakes. The strange-looking organelle finishes the process of protein synthesis by decorating the proteins with highly specialized arrangements of sugars. The final sugar-coated molecule is then sent out into the cell to aid in cell communication and to help determine the cell’s function in the body.

Martin’s artificial Golgi functions in a surprisingly similar way to the natural Golgi, but he gives the ancient organelle a very high-tech makeover. His chip looks similar to a miniature checker board where sugars, enzymes, and other basic cell materials are suspended in water and can be transported and mixed by applying electric currents to the destination squares on the checker board. Through this process sugars can be built in an automated fashion where they are exposed to a variety of enzymes found in the natural Golgi. The resulting sugars can then be tested on living cells either on the chip or in the lab to determine their effects. With the chip’s ability to process many combinations of sugars and enzymes, it could help researchers quickly uncover new sugar-based drugs, according to Martin.

Scientists have known for years that certain sugars can serve as extremely beneficial therapeutics for humans. One well-known example is heparin, which is among the most widely used drugs in the world. Heparin is formed naturally in the Golgi organelle in cells of the human body as well as in other animals like pigs. Heparin acts as an anticoagulant preventing blood clots, which makes it a good therapeutic for heart, stroke, and dialysis patients.

The main source of heparin is currently the intestines of foreign livestock and, as recent news reports highlight, the risk of contamination from such sources is high. So researchers are working around the clock to develop a safer, man-made alternative to the drug that will prevent outside contamination. A synthetic alternative would build the sugar from scratch, helping eliminate the possibility of contamination he explained.

“I am very grateful to have the privilege of working with Dr. Linhardt who has discovered the recipe to make fully synthetic heparin,” Martin said. “Because we know the recipe, I am going to use it as a model to test the device. If our artificial Golgi can build fully functional heparin, we can then use the artificial organelle to produce many different sugar variants by altering the combination of enzymes used to synthesize them. Another great thing about these devices is that they are of microscale size, so that if needed we could fill an entire room with them to increase throughput for drug discovery.”

There are millions of possible sugar combinations that can be formed and scientists currently only know the function of very few of them like heparin. “Since it is known that these types of sugars play a part in many important biological processes such as cell growth, cell differentiation, blood coagulation, and viral defense mechanisms, we feel that that this artificial Golgi will help our team to develop a next generation of sugar-based drugs, known as glycotheraputics,” Martin said. “We are going to start making new combinations and we simply don’t know what we are going to find. We could find a sugar whose signal blocks the spread of cancer cells or initiates the differentiation of stem cells. We just don’t know.”

Martin, a Barry M. Goldwater Scholar and native of the small town of Boylston, Mass., is graduating from Rensselaer on May 17, 2008 with a nearly perfect GPA. He plans to continue on at Rensselaer as a graduate student, working with Linhardt to test and further develop his artificial Golgi.

[Gabrielle DeMarco @ Rensselaer Polytechnic Institute]

The dime-sized laser, to be described Thursday, May 8, at the Conference on Lasers and Electro-Optics, emits 10 billion pulses per second, each lasting about 40 femtoseconds (quadrillionths of a second), with an average power of 650 milliwatts. For comparison, the new laser produces pulses 10 times more often than a standard NIST frequency comb while producing much shorter pulses than other lasers operating at comparable speeds. The new laser is also 100 to 1000 times more powerful than typical high-speed lasers, producing clearer signals in experiments. The laser was built by Albrecht Bartels at the Center for Applied Photonics of the University of Konstanz.

Among its applications, the new laser can be used in searches for planets orbiting distant stars. Astronomers look for slight variations in the colors of starlight over time as clues to the presence of a planet orbiting the star. The variations are due to the small wobbles induced in the star’s motion as the orbiting planet tugs it back and forth, producing minute shifts in the apparent color (frequency) of the starlight. Currently, astronomers’ instruments are calibrated with frequency standards that are limited in spectral coverage and stability. Frequency combs could be more accurate calibration tools, helping to pinpoint even smaller variations in starlight caused by tiny Earthlike planets. Such small planets would cause color shifts equivalent to a star wobble of just a few centimeters per second. Current instruments can detect, at best, a wobble of about 1 meter per second.

Standard frequency combs have “teeth” that are too finely spaced for astronomical instruments to read. The faster laser is one approach to solving this problem. In a separate paper, the NIST group and astronomer Steve Osterman at the University of Colorado at Boulder describe how, by bouncing the light between sets of mirrors a particular distance apart, they can eliminate periodic blocks of teeth to create a gap-toothed comb. This leaves only every 10th or 20th tooth, making an ideal ruler for astronomy.

Both approaches have advantages for astronomical planet finding and related applications. The dime-sized laser is very simple in construction and produces powerful and extremely well-defined comb teeth. On the other hand, the filtering approach can cover a broader range of wavelengths. Four or five filtering cavities in parallel would provide a high-precision comb of about 25,000 evenly spaced teeth that spans the visible to near-infrared wavelengths (400 to 1100 nanometers), NIST physicist Scott Diddams says.

Osterman says he is pursuing the possibility of testing such a frequency comb at a ground-based telescope or launching a comb on a satellite or other space mission. Other possible applications of the new laser include remote sensing of gases for medical or atmospheric studies, and on-the-fly precision control of high-speed optical communications to provide greater versatility in data and time transmissions. The application of frequency combs to planet searches is of international interest and involves a number of major institutions such as the Max-Planck Institute for Quantum Optics and Harvard Smithsonian Center for Astrophysics.

[Laura Ost @ National Institute of Standards and Technology (NIST)]