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Fast Blasts

For over twenty years, investigators at the nanoscale have been using AFMs (atomic force microscopes) to image individual atoms and push them into stable configurations on a smooth surface. Now, for the first time, researchers at the Nanophysics and Soft Matter Group at the University of Bristol have built an AFM that operates so quickly that nanofabrication can be conducted in real time. This could be an important step to future technologies based on mass nanofabrication.

The group’s improved AFM works by selectively oxidizing silicon to produce a desired pattern. Instead of conventional AFM tips, which move at about 1-100 um/s — not much faster than the speed of a crawling amoeba — this new AFM can operate at speeds in excess of 1 cm/s, more than 10,000 times faster.

The penalty for such rapid operation is a faster degradation rate for the AFM tip, which is made more durable by covering it with a platinum coating. Though the AFM has proven its ability to avoid damaging the nanostructures it is working on, with no damage observed after more than 250 pass-overs, it did lose manufacturing resolution over the course of several experiments.

Olaf Sporns, a professor at Indiana University, represents the leading edge of research into information flow within the brain, and in applying that knowledge to create neurorobots that learn. Last year, his lab produced the first detailed map of the human cortex using a new and powerful type of brain imaging called diffusion imaging. This map singled out a “cortical core” in the posterior medial and parietal cerebral cortex, sections of the brain near the back of the head.

Network studies in fields like computer science and biology suggest that strongly interconnected central nodes often mediate functions responsible for properties of the entire network. This suggests that the cortical core could be the key to treating cognitive disorders like Alzheimer’s and schizophrenia, or for enhancing the human brain’s processing ability.

Besides his pioneering work in brain modeling, Dr. Sporns also creates neurorobots piloted by cultures of a few thousand neurons to learn more about how the human brain processes rewards. (For more on Neurobots, see also Here Come the Neurobots in this issue.)

Ray Baughman is flexing some major artificial muscle. The muscle he and his colleagues at the University of Texas in Dallas have designed has so many advantages over past proposed projects that one wonders how such a major leap could occur without incremental progress in between. Baughman’s artificial muscle is a ribbon made of tangled carbon nanotube “aerogel”, meaning it is mostly empty space and weighs little more than its volume in air.

Despite its feather-light weight, the material is stiffer than diamond in its “long” direction, while stretchy like rubber in the “wide” direction. It is so stretchy, in fact, that the application of a modest voltage causes it to widen by 220%. It maintains these properties under an extremely wide temperature range — from -320.8 °F (-196 °C), the temperature of liquid nitrogen, to 2,800 °F (1,538 °C ), above the melting point of iron. No previous attempt at artificial muscles even comes close to its potential usefulness.

There is one major drawback to these artificial muscles in their current form, however — they’re only as strong as human muscle by weight, meaning that a truly practical version would need to be much denser, or have substantially more volume.

Using a powerful new extension of fMRI technology called HARDI, scientist Paul Thompson and colleagues at the university of California, Los Angeles scanned the brains of 23 sets of identical twins and the same number of fraternal twins. The technology, which measures the amount of water diffusing through white matter in the brain, indirectly measures the integrity of myelin sheathing and therefore the speed of nerve impulses.

By extensive analysis and cross-checking of the identical twins (who share 100% of their genetic material) and fraternal twins (who share 50%), the researchers were able to determine that myelin integrity in parts of the brain that are important for intelligence is determined by genetics. This adds to previous research that found that the volume of the brain’s grey matter (which correlates with IQ) is heritable, as is the amount of white matter, which provides crucial connections between neurons.

The researchers pointed out that the genetic determination of elements of intelligence isn’t immutable. To the contrary, it leaves the door open for future intelligence enhancement therapies.

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