Ancient Egypt's Pyramids: Norwegian Researcher Unlocks Construction Secrets

Ancient Egypt's Pyramids: Norwegian Researcher Unlocks Construction Secrets

  6:00:00 PM    Science Lover

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Scientists from around the world have tried to understand how the Egyptians erected their giant pyramids. Now, an architect and researcher at the Norwegian University of Science and Technology (NTNU) says he has the answer to this ancient, unsolved puzzle.

The precision system of Khufu's Great Pyramid.
(Credit: Ole J. Bryn / NTNU)

Researchers have been so preoccupied by the weight of the stones that they tend to overlook two major problems: How did the Egyptians know exactly where to put the enormously heavy building blocks? And how was the master architect able to communicate detailed, highly precise plans to a workforce of 10,000 illiterate men?

A 7-million-ton structure

These were among the questions that confronted Ole J. Bryn, an architect and associate professor in NTNU's Faculty of Architecture and Fine Art when he began examining Khufu's Great Pyramid in Giza. Khufu's pyramid, better known as the Pyramid of Cheops, consists of 2.3 million limestone blocks weighing roughly 7 million tons. At 146.6 meters high, it held the record as the tallest structure ever built for nearly 4000 years.

What Bryn discovered was quite simple. He believes that the Egyptians invented the modern building grid, by separating the structure's measuring system from the physical building itself, thus introducing tolerance, as it is called in today's engineering and architectural professions.

The apex point a key

Bryn has studied the plans from the thirty oldest Egyptian pyramids, and discovered a precision system that made it possible for the Egyptians to reach the pyramid's last and highest point, the apex point, with an impressive degree of accuracy. By exploring and making a plan of the pyramid it is possible to prepare modern project documentation of not just one, but all pyramids from any given period.

As long as the architect knows the main dimensions of a pyramid, he can project the building as he would have done it with a modern building, but with building methods and measurements known from the ancient Egypt, Bryn says.

In a scientific article published May 2010 in the Nordic Journal of Architectural Research, Bryn discusses aspects that can explain the construction of a multitude of the Egyptian pyramids by taking the building grid, and not the physical building itself, as the starting point for the analysis.

A new map

If the principles behind Bryn's drawings are correct, then archaeologists will have a new "map" that demonstrates that the pyramids are not a "bunch of heavy rocks with unknown structures" but, rather, incredibly precise structures.

Ole J. Bryn's findings will be presented and explained at the exhibition The Apex Point in Trondheim from September 13th to October 1st. The exhibition is an official part of the program to celebrate the centenary (1910-2010) of the Norwegian University of Science and Technology.

About the author:

Ole J. Bryn is a former practising architect, and currently holds a position as Associate Professor at the Faculty of Architecture and Fine Art, the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway.

The development of Bryn's theories on the building grids used in Egyptian pyramids has benefited from cooperation with Dr. Michel Barsoum, Grosvenor and Distinguished Professor at the Department of Materials Science and Engineering, Drexel University, Philadelphia.

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Mimicking Nature, Water-Based Artificial Leaf Produces Electricity

Mimicking Nature, Water-Based Artificial Leaf Produces Electricity

  1:11:00 PM    Science Lover

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A team led by a North Carolina State University researcher has shown that water-gel-based solar devices -- "artificial leaves" -- can act like solar cells to produce electricity. The findings prove the concept for making solar cells that more closely mimic nature. They also have the potential to be less expensive and more environmentally friendly than the current standard-bearer: silicon-based solar cells.

Just as real leaves do, water-gel-based solar devices can act like solar cells to produce electricity, new research shows. (Credit: iStockphoto/Chaikovskiy Igor)

The bendable devices are composed of water-based gel infused with light-sensitive molecules -- the researchers used plant chlorophyll in one of the experiments -- coupled with electrodes coated by carbon materials, such as carbon nanotubes or graphite. The light-sensitive molecules get "excited" by the sun's rays to produce electricity, similar to plant molecules that get excited to synthesize sugars in order to grow, says NC State's Dr. Orlin Velev, Invista Professor of Chemical and Biomolecular Engineering and the lead author of a paper published online in the Journal of Materials Chemistry describing this new generation of solar cells.

Velev says that the research team hopes to "learn how to mimic the materials by which nature harnesses solar energy." Although synthetic light-sensitive molecules can be used, Velev says naturally derived products -- like chlorophyll -- are also easily integrated in these devices because of their water-gel matrix.

Now that they've proven the concept, Velev says the researchers will work to fine-tune the water-based photovoltaic devices, making them even more like real leaves.

"The next step is to mimic the self-regenerating mechanisms found in plants," Velev says. "The other challenge is to change the water-based gel and light-sensitive molecules to improve the efficiency of the solar cells."

Velev even imagines a future where roofs could be covered with soft sheets of similar electricity-generating artificial-leaf solar cells.

"We do not want to overpromise at this stage, as the devices are still of relatively low efficiency and there is a long way to go before this can become a practical technology," Velev says. "However, we believe that the concept of biologically inspired 'soft' devices for generating electricity may in the future provide an alternative for the present-day solid-state technologies."

Researchers from the Air Force Research Laboratory and Chung-Ang University in Korea co-authored the study. The study was funded by the Air Force Research Laboratory and the U.S. Department of Energy. The work is part of NC State's universitywide nanotechnology program, Nano@NC State.

NC State's Department of Chemical and Biomolecular Engineering is part of the university's College of Engineering.

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Turning Thoughts into Words A new approach allows more information to be extracted from the brain.

Turning Thoughts into Words A new approach allows more information to be extracted from the brain.

  2:23:00 AM    Science Lover

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Brain-computer interfaces could someday provide a lifeline to "locked-in" patients, who are unable to talk or move but are aware and awake. Many of these patients can communicate by blinking their eyes, but turning blinks into words is time-consuming and exhausting.

Scientists in Utah have now demonstrated a way to determine which of 10 distinct words a person is thinking by recording the electrical activity from the surface of the brain.

Brian interface: The micro electrodes
shown here were used to record brain
signals in order to decode ten words
from a patient’s thoughts.
Credit: Spencer Kellis, University of Utah

The new technique involves training algorithms to recognize specific brain signals picked up by an array of nonpenetrating electrodes placed over the language centers of the brain, says Spencer Kellis, one of the bioengineers who carried out the work at the University of Utah, in Salt Lake City. The approach used is known as electrocorticography (ECoG). The group was able to identify the words "yes," "no," "hot, "cold," "thirsty," "hungry," "hello," "goodbye," "more," and "less" with an accuracy of 48 percent.

"The accuracy definitely needs to be improved," says Kellis. "But we have shown the information is there."

Individual words have been decoded from brain signals in the past using functional magnetic resonance imaging (fMRI), says Eric Leuthardt, director of the Center for Innovation in Neuroscience and Technology at Washington University School of Medicine in St. Louis, Missouri. This is the first time that the feat has been performed using ECoG, a far more practical and portable approach than fMRI, he says.

Working with colleagues Bradley Greger and Paul House, Kellis placed 16 electrodes on the surface of the brain of a patient being treated for epilepsy. The electrodes recorded signals from the facial motor cortex--an area of the brain that controls face muscles during speech--and over the Wernicke's area, part of the cerebral cortex that is linked with language. To train the algorithm, signals were analyzed as the patient was asked to repeatedly utter the 10 words.

ECoG has long been used to locate the source of epileptic seizures in the brain. But electrodes used are typically several hundred microns in size and are positioned centimeters apart, says Kellis. "The brain is doing processing at a much finer spatial scale than is really detectable by these standard clinical electrodes," he says. The Utah team used a new type of microelectrode array developed by PMT Neurosurgical. The electrodes are much smaller--40 microns in size--and are separated by a couple of millimeters.

It's possible to use less invasive techniques, such as electroencephalography (EEG), which places electrodes on the scalp, to enable brain-to-computer communications. Adrian Owen, a senior scientist in the Cognition and Brain Sciences Unit at the University of Cambridge, UK, has shown that EEG signals can be used to allow people in a persistent vegetative state to communicate "yes" and "no."

But with EEG, many of the signals are filtered out by the skull, says Leuthardt. "What's really nice about ECoG is its potential to give us a lot more information," he says.

Decoding 10 words is "very cool," says Owen, but the accuracy will need to improve dramatically, given the patients the technology is aimed at. "I don't think even 60 percent or 70 percent accuracy is going to work for patients who cannot communicate in any other way and where there is no other margin for verification," he says.

Ultimately, the hope is that ECoG will enable much more sophisticated communication. Last year Leuthardt showed that ECoG could be used to decode vowel and consonant sounds--an approach that might eventually be used to reconstruct a much larger number of complete words.

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Einstein's Relativity at a Personal ScalePair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale

Einstein's Relativity at a Personal ScalePair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale

  10:12:00 AM    Science Lover

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Scientists have known for decades that time passes faster at higher elevations -- a curious aspect of Einstein's theories of relativity that previously has been measured by comparing clocks on the earth's surface and a high-flying rocket.

Now, physicists at the National Institute of Standards and Technology (NIST) have measured this effect at a more down-to-earth scale of 33 centimeters, or about 1 foot, demonstrating, for instance, that you age faster when you stand a couple of steps higher on a staircase.

NIST physicists compared a pair of the world's best atomic clocks to demonstrate that you age faster when you stand just a couple of steps higher on a staircase. (Credit: Loel Barr for NIST)

Described in the Sept. 24 issue of Science, the difference is much too small for humans to perceive directly -- adding up to approximately 90 billionths of a second over a 79-year lifetime -- but may provide practical applications in geophysics and other fields.

Similarly, the NIST researchers observed another aspect of relativity -- that time passes more slowly when you move faster -- at speeds comparable to a car travelling about 20 miles per hour, a more comprehensible scale than previous measurements made using jet aircraft.

NIST scientists performed the new "time dilation" experiments by comparing operations of a pair of the world's best experimental atomic clocks. The nearly identical clocks are each based on the "ticking" of a single aluminum ion (electrically charged atom) as it vibrates between two energy levels over a million billion times per second. One clock keeps time to within 1 second in about 3.7 billion years and the other is close behind in performance. The two clocks are located in different laboratories at NIST and connected by a 75-meter-long optical fiber.

NIST's aluminum clocks -- also called "quantum logic clocks" because they borrow logical decision-making techniques from experimental quantum computing -- are precise and stable enough to reveal slight differences that could not be seen until now. The clocks operate by shining laser light on the ions at optical frequencies, which are higher than the microwave frequencies used in today's standard atomic clocks based on the cesium atom.

Optical clocks could someday lead to time standards 100 times more accurate than today's standard clocks.

The aluminum clocks can detect small relativity-based effects because of their extreme precision and high "Q factor" -- a quantity that reflects how reliably the ion absorbs and retains optical energy in changing from one energy level to another -- says NIST postdoctoral researcher James Chin-Wen Chou, first author of the paper.

"We have observed the highest Q factor in atomic physics," Chou says. "You can think about it as how long a tuning fork would vibrate before it loses the energy stored in the resonating structure. We have the ion oscillating in sync with the laser frequency for about 400 thousand billion cycles."

The NIST experiments focused on two scenarios predicted by Einstein's theories of relativity. First, when two clocks are subjected to unequal gravitational forces due to their different elevations above the surface of the Earth, the higher clock -- experiencing a smaller gravitational force -- runs faster. Second, when an observer is moving, a stationary clock's tick appears to last longer, so the clock appears to run slow. Scientists refer to this as the "twin paradox," in which a twin sibling who travels on a fast-moving rocket ship would return home younger than the other twin. The crucial factor is the acceleration (speeding up and slowing down) of the travelling twin in making the round-trip journey.

NIST scientists observed these effects by making specific changes in one of the two aluminum clocks and measuring the resulting differences in the two ions' relative ticking rates, or frequencies.

In one set of experiments, scientists raised one of the clocks by jacking up the laser table to a height one-third of a meter (about a foot) above the second clock. Sure enough, the higher clock ran at a slightly faster rate than the lower clock, exactly as predicted.

The second set of experiments examined the effects of altering the physical motion of the ion in one clock. (The ions are almost completely motionless during normal clock operations.) NIST scientists tweaked the one ion so that it gyrated back and forth at speeds equivalent to several meters per second. That clock ticked at a slightly slower rate than the second clock, as predicted by relativity. The moving ion acts like the traveling twin in the twin paradox.

Such comparisons of super-precise clocks eventually may be useful in geodesy, the science of measuring the Earth and its gravitational field, with applications in geophysics and hydrology, and possibly in space-based tests of fundamental physics theories, suggests physicist Till Rosenband, leader of NIST's aluminum ion clock team.

NIST scientists hope to improve the precision of the aluminum clocks even further, as much as 10-fold, through changes in ion trap geometry and better control of ion motion and environmental interference. The aim is to measure differences in timekeeping well enough to measure heights to an accuracy of 1 centimeter, a performance level suitable for making geodetic measurements. The paper suggests that optical clocks could be linked to form a network of "inland tidal gauges" to measure the distance from the earth's surface to the geoid (the surface of the earth's gravity field that matches the global mean sea level). Such a network could be updated far more frequently than current techniques.

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Robotic Arm's Big Flaw: Patients in Wheelchairs Say It's 'Too Easy'

Robotic Arm's Big Flaw: Patients in Wheelchairs Say It's 'Too Easy'

  10:02:00 AM    Science Lover

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One touch directs a robotic arm to grab objects in a new computer program designed to give people in wheelchairs more independence. University of Central Florida researchers thought the ease of the using the program's automatic mode would be a huge hit. But they were wrong -- many participants in a pilot study didn't like it because it was "too easy."

Bob Melia, a quadriplegic who advised the UCF team, says the new technology will make life easier for thousands of people who are so dependent on others because of physical limitations. (Credit: Jason Greene, UCF)

Most participants preferred the manual mode, which requires them to think several steps ahead and either physically type in instructions or verbally direct the arm with a series of precise commands. They favored the manual mode even though they did not perform tasks as well with it.

"We focused so much on getting the technology right," said Assistant Professor Aman Behal. "We didn't expect this."

John Bricout, Behal's collaborator and the associate dean for Research and Community Outreach at the University of Texas at Arlington School of Social Work, said the study demonstrates how people want to be engaged -- but not overwhelmed -- by technology. The psychology theory of Flow describes this need to have a balance between challenge and capacity in life.

"If we're too challenged, we get angry and frustrated. But if we aren't challenged enough, we get bored," said Bricout, who has conducted extensive research on adapting technology for users with disabilities. "We all experience that. People with disabilities are no different."

The computer program is based on how the human eye sees. A touch screen, computer mouse, joystick or voice command sends the arm into action. Then sensors mounted on the arm see an object, gather information and relay it to the computer, which completes the calculations necessary to move the arm and retrieve the object.

Behal is seeking grants to translate the study's findings into a smoother "hybrid" mode that is more interactive and challenging for users and features a more accurate robotic arm. Laser, ultrasound and infrared technology coupled with an adaptive interface will help him achieve his goals.

The key is to design technology that can be individualized with ease, Behal said. Some patients will have more mobility than others, and they may prefer a design closer to the manual mode. Though the automatic mode wasn't popular in the pilot study, it may be the best option for patients with more advanced disease and less mobility.

Bob Melia, a quadriplegic who advised the UCF team, says the new technology will make life easier for thousands of people who are so dependent on others because of physical limitations.

"You have no idea what it is like to want to do something as simple as scratching your nose and have to rely on someone else to do it for you," Melia said. "I see this device as someday giving people more freedom to do a lot more things, from getting their own bowl of cereal in the morning to scratching their nose anytime they want."

Behal's initial research was funded with a grant from the National Science Foundation and through a pilot grant from the National Multiple Sclerosis Society. Behal presented his findings at the 2010 International Conference on Robotics and Automation in Anchorage, Alaska.

Behal is collaborating with Bricout, who previously worked in the College of Health and Public Affairs at UCF, to apply for another grant in the area of assistive technology.

The research team includes Dae-Jin Kim, Zhao Wang, and Rebekah Hazlett from UCF, John Bricout from UT Arlington, and Heather Godfrey, Greta Rucks, David Portee and Tara Cunningham from Orlando Health Rehabilitation Institute. The institute helped recruit patients for the study.

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Brain Coprocessors The need for operating systems to help brains and machines work together.

Brain Coprocessors The need for operating systems to help brains and machines work together.

  9:50:00 AM    Science Lover

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The last few decades have seen a surge of invention of technologies that enable the observation or perturbation of information in the brain. Functional MRI, which measures blood flow changes associated with brain activity, is being explored for purposes as diverse as lie detection, prediction of human decision making, and assessment of language recovery after stroke.

Implanted electrical stimulators, which enable control of neural circuit activity, are borne by hundreds of thousands of people to treat conditions such as deafness, Parkinson's disease, and obsessive-compulsive disorder. And new methods, such as the use of light to activate or silence specific neurons in the brain, are being widely utilized by researchers to reveal insights into how to control neural circuits to achieve therapeutically useful changes in brain dynamics. We are entering a neurotechnology renaissance, in which the toolbox for understanding the brain and engineering its functions is expanding in both scope and power at an unprecedented rate.

This toolbox has grown to the point where the strategic utilization of multiple neurotechnologies in conjunction with one another, as a system, may yield fundamental new capabilities, both scientific and clinical, beyond what they can offer alone. For example, consider a system that reads out activity from a brain circuit, computes a strategy for controlling the circuit so it enters a desired state or performs a specific computation, and then delivers information into the brain to achieve this control strategy. Such a system would enable brain computations to be guided by predefined goals set by the patient or clinician, or adaptively steered in response to the circumstances of the patient's environment or the instantaneous state of the patient's brain.

Some examples of this kind of "brain coprocessor" technology are under active development, such as systems that perturb the epileptic brain when a seizure is electrically observed, and prosthetics for amputees that record nerves to control artificial limbs and stimulate nerves to provide sensory feedback. Looking down the line, such system architectures might be capable of very advanced functions--providing just-in-time information to the brain of a patient with dementia to augment cognition, or sculpting the risk-taking profile of an addiction patient in the presence of stimuli that prompt cravings.

Given the ever-increasing number of brain readout and control technologies available, a generalized brain coprocessor architecture could be enabled by defining common interfaces governing how component technologies talk to one another, as well as an "operating system" that defines how the overall system works as a unified whole--analogous to the way personal computers govern the interaction of their component hard drives, memories, processors, and displays. Such a brain coprocessor platform could facilitate innovation by enabling neuroengineers to focus on neural prosthetics at an algorithmic level, much as a computer programmer can work on a computer at a conceptual level without having to plan the fate of every individual bit. In addition, if new technologies come along, e.g., a new kind of neural recording technology, they could be incorporated into a system, and in principle rapidly coupled to existing computation and perturbation methods, without requiring the heavy readaptation of those other components.

Developing such brain coprocessor architectures would take some work--in particular, it would require technologies standardized enough, or perhaps open enough, to be interoperable in a variety of combinations. Nevertheless, much could be learned from developing relatively simple prototype systems. For example, recording technologies by themselves can report brain activity, but cannot fully attest to the causal contribution that the observed brain activity makes to a specific behavioral or clinical outcome; control technologies can input information into neural targets, but by themselves their outcomes might be difficult to interpret due to endogenous neural information and unobserved neural processing. These scientific issues can be disambiguated by rudimentary brain coprocessors, built with readily available off-the-shelf components, that use recording technologies to assess how a given neural circuit perturbation alters brain dynamics. Such explorations may begin to reveal principles governing how best to control a circuit--revealing the neural targets and control strategies that most efficaciously lead to a goal brain state or behavioral effect, and thus pointing the way to new therapeutic strategies. Miniature, implantable brain coprocessors might be able to support new kinds of personalized medicine, for example continuously adapting a neural control strategy to the goals, state, environment, and history of an individual patient--important powers, given the dynamic nature of many brain disorders.

In the future, the computational module of a brain coprocessor may be powerful enough to assist in high-level human cognition or complex decision making. Of course, the augmentation of human intelligence has been one of the key goals of computer engineers for well over half a century. Indeed, if we relax the definition of brain coprocessor just a bit, so as not to require direct physical access to the brain, many consumer technologies being developed today are converging upon brain coprocessor-like architectures. A large number of new technologies are attempting to discover information useful to a user and to deliver this information to the user in real time. Also, these discovery and delivery processes are increasingly shaped by the environment (e.g., location) and history (e.g., social interactions, searches) of the user. Thus we are seeing a departure from the classical view (as initially anticipated by early thinkers about human-machine symbiosis such as J. C. R. Licklider) in which computers receive goals from humans, perform defined computations, and then provide the results back to humans.

Of course, giving machines the authority to serve as proactive human coprocessors, and allowing them to capture our attention with their computed priorities, has to be considered carefully, as anyone who has lost hours due to interruption by a slew of social-network updates or search-engine alerts can attest. How can we give the human brain access to increasingly proactive coprocessing technologies without losing sight of our overarching goals? One idea is to develop and deploy metrics that allow us to evaluate the IQ of a human plus a coprocessor, working together--evaluating the performance of collaborating natural and artificial intelligences in a broad battery of problem-solving contexts. After all, humans with Internet-based brain coprocessors (e.g., laptops running Web browsers) may be more distractible if the goals include long, focused writing tasks, but they may be better at synthesizing data broadly from disparate sources; a given brain coprocessor configuration may be good for some problems but bad for others. Thinking of emerging computational technologies as brain coprocessors forces us to think about them in terms of the impacts they have on the brain, positive and negative, and importantly provides a framework for thoughtfully engineering their direct, as well as their emergent, effects.

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Credit Card with a Computer Inside A smarter credit card could mean new security features and other functionality.

Credit Card with a Computer Inside A smarter credit card could mean new security features and other functionality.

  10:09:00 AM    Science Lover

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A programmable credit card can display useful information, offer added security features, and even act as several different cards by rewriting its own magnetic strip.

Smarter card: A user has to enter a PIN to display this
card’s full number and unlock its magnetic stripe for use
either online or in-store. After a short time the display
and magnetic stripe become blank again.
Credit: Dynamics

Two types of programmable credit cards were unveiled this week at the DEMO conference in Santa Clara, California, by Dynamics, a startup based in Pittsburgh that's been developing the technology in stealth mode for three years. The company raised $5.7 million of funding last year.

The new cards are no bigger than the one in your wallet, and is actually slightly more flexible. It can display information at the press of a button, and can become several different cards by rewriting its own magnetic strip.

The "MultiAccount" card has two buttons on its face, each with an indicator light that can be pressed to record data to its magnetic strip. "One might switch the card to be your debit card, and the other your credit card," says Dynamics CEO Jeff Mullen. "These cards are exactly the same size and thickness of a conventional card, and the lithium-polymer battery inside can last four years under high usage. They're also fully waterproof, so you can put them through the washing machine."

The "Hidden" card features a keypad and black-and-white display for six of the digits in the card's unique number. Once the correct PIN is entered on the card's four buttons, the missing digits are filled in and the card's magnetic strip is populated with data. Both the digits and the strip become blank again after a short time. "If this card is lost, it's just dead plastic to anyone who finds it," says Mullen, who thinks it could help banks attract security-conscious consumers.

That may be true, says Avivah Litan, a Gartner analyst who researches security and technology in the financial sector, but "most card data is stolen electronically, in large volumes," she notes. As a result, banks "may prevent a few percentage points [of fraud], but it seems unlikely to be worth the investment for them."

The MultiAccount card may be more attractive to the financial sector than the "Hidden" card. "It could help the very large card issuers, such as Chase, that have a lot of overlap between their credit and debit accounts," says Litan. However, convincing banks to invest in an unproven technology will require the potential for a very strong effect on their bottom lines, she says.

Mullen says Dynamics's cards are significantly more expensive to produce than standard credit cards, but argues that the additional cost is offset by the benefits to a bank. "These cards are significant revenue generators for them, not cost centers," he says.

Banks already target different types of cards to particular demographics, and use reward schemes to attract new business and encourage heavy use of their products. Cards with computational smarts inside could enable more of that, Mullen argues. For example, a credit card that can suddenly act as a loyalty card might encourage customers to use a scheme that they otherwise wouldn't.

"Cards with this technology have been used in large numbers in stealth trials in the U.S. since earlier this year," says Mullen, who adds that banking partners will begin talking about their plans for the technology in coming months. A particular attraction for banks, he says, is that the cards are compatible with existing infrastructure, unlike contactless payments based on RFID chips.

"There are 16 million magnetic stripe readers in the world," he says. "It's hard to change that, but easy to upgrade your own cards without building new infrastructure."

Dynamics is also working on cards that include E Ink-style displays that remain switched on for longer periods, and the company is also investigating a card that can transfer more data. Typically only a third of the magnetic strip on a card carries the card's details, says Mullen. "You can send messages between card and reader using the rest of that area."

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Your Body Recycling Itself -- Captured on Film

Your Body Recycling Itself -- Captured on Film

  8:26:00 PM    Science Lover

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Our bodies recycle proteins, the fundamental building blocks that enable cell growth and development. Proteins are made up of a chain of amino acids, and scientists have known since the 1980s that first one in the chain determines the lifetime of a protein. McGill researchers have finally discovered how the cell identifies this first amino acid -- and caught it on camera.

This image shows UBR-box recognition of an arginine residue at the beginning of a protein (blue) targeted for degradation. The structural integrity of the UBR box depends on zinc (grey) and a histidine residue (red) that is mutated in Johanson-Blizzard syndrome. (Credit: Department of Biochemistry, McGill University.)

"There are lots of reasons cells recycle proteins -- fasting, which causes loss of muscle, growth and remodeling during development, and normal turnover as old proteins are replaced to make new ones," explained lead researcher, Dr. Kalle Gehring, from McGill's Department of Biochemistry. "One way that cells decide which proteins to degrade is the presence of a signal known as an N-degron at the start of the protein. By X-ray crystallography, we discovered that the N-degron is recognized by the UBR box, a component of the cells' recycling system."

The powerful technique can pinpoint the exact location of atoms and enabled the team to capture an image of the UBR box, providing insight to this incredibly tiny yet essential part of our bodies' chemical mechanics.

Aside from representing a major advance in our understanding of the life cycle of proteins, the research has important repercussions for Johanson-Blizzard syndrome, a rare disease that causes deformations and mental retardation. This syndrome is caused by a mutation in the UBR box that causes it to lose an essential zinc atom. Better understanding of the structure of the UBR box may help researchers develop treatments for this syndrome.

The research was published in Nature Structural & Molecular Biology and received funding from the Canadian Institutes of Health Research.

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Nano Antenna Concentrates Light

Nano Antenna Concentrates Light

  8:15:00 PM    Science Lover

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Everybody who's ever used a TV, radio or cell phone knows what an antenna does: It captures the aerial signals that make those devices practical. A lab at Rice University has built an antenna that captures light in the same way, at a small scale that has big potential.

This is a colorized scanning electron microscope 
image of gold tips in a nanogap device used in 
experiments to capture and amplify light. 
(Credit: Natelson Lab/Rice University)

Condensed matter physicist Doug Natelson and graduate student Dan Ward have found a way to make an optical antenna from two gold tips separated by a nanoscale gap that gathers light from a laser. The tips "grab the light and concentrate it down into a tiny space," Natelson said, leading to a thousand-fold increase in light intensity in the gap.

Getting an accurate measurement of the effect is a first, said Natelson, who reported the results in the September 19 online edition of the journal Nature Nanotechnology. He expects the discovery will be useful in the development of tools for optics and for chemical and biological sensing, even at the single-molecule scale, with implications for industrial safety, defense and homeland security.

The paper by Natelson, Ward and their colleagues in Germany and Spain details the team's technique, which involves shining laser light into the gap between a pair of gold tips less than a nanometer apart -- about a hundred-thousandth the width of a human hair.

"You can ignore the fact that your car antenna is built out of atoms; it just works," said Natelson, a Rice professor of physics and astronomy, and also electrical and computer engineering. "But when you have tiny pieces of metal very close to each other, you have to worry about all the details. The fields are going to be big, the situation's going to be complicated and you're really constrained. We've been able to use some physics that only come into play when things are very close together to help figure out what's going on."

The key to measuring light amplification turned out to be measuring something else, specifically the electrical current flowing between the gold tips.

Putting the nanotips so close together allows charge to flow via quantum tunneling as the electrons are pushed from one side to the other. The researchers could get electrons moving by pushing them at low frequencies with a voltage, in a highly controllable, measurable way. They could also get them flowing by shining the laser, which pushes the charge at the very high frequency of the light. Being able to compare the two processes set a standard by which the light amplification could be determined, Natelson said. Their German and Spanish coauthors helped supply the necessary theoretical justification for the analysis.

The amplification is a plasmonic effect, Natelson said. Plasmons, which may be excited by light, are oscillating electrons in metallic structures that act like ripples in a pool. "You've got a metal structure, you shine light on it, the light makes the electrons in this metal structure slosh around," he said. "You can think of the electrons in the metal as an incompressible fluid, like water in a bathtub. And when you get them sloshing back and forth, you get electric fields.

"At the surfaces of the metal, these fields can be very big -- much bigger than those from the original radiation," he said. "What was hard to measure was just how big. We didn't know how much the two sides were sloshing up and down -- and that's exactly the thing we care about."

By simultaneously measuring the low-frequency electrically driven and the high-frequency optically driven currents between the tips, "we can figure out the voltage zinging back and forth at the really high frequencies that are characteristic of light," he said.

Natelson said his lab's homebuilt apparatus, which combines nanoscale electronics and optics, is fairly unusual. "There are a lot of people who do optics. There are a lot who do nanoscale electrical measurements," he said. "There are still not too many people who combine the two."

The custom rig gave the Rice researchers a measure of control over thermal and electrical properties that have stymied other investigators. The tips are cooled to 80 Kelvin, about -315 degrees Fahrenheit, and are electrically insulated from their silicon bases, keeping at bay stray voltages that could skew the results.

"The reason we're studying these enhanced fields is not just because they're there," Natelson said. "If you can enhance the local field by a factor of 1,000, there are lots of things you can do in terms of sensors and non-linear optics. Anything that gives you a handle on what's happening at these tiny scales is very useful.

"This is one of those rare, happy cases where you are able to actually get information -- very local information -- about exactly something you care about."

The paper's co-authors are Falco Hüser and Fabian Pauly of the Karlsruhe Institute of Technology, Germany; and Juan Carlos Cuevas at the Autonomous University of Madrid, Spain.

Support for the project came from the Robert A. Welch Foundation, the Lockheed Martin Advanced Nanotechnology Center of Excellence at Rice (LANCER), Deutsche Forschungsgemeinschaft, the Baden-Württemberg Siftung, the European Union through the Bio-Inspired Approaches for Molecular Electronics (BIMORE) network, and the Spanish Ministry of Science and Innovation.

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Geckos Inspire New Method to Print Electronics on Complex Surfaces

Geckos Inspire New Method to Print Electronics on Complex Surfaces

  11:49:00 AM    Science Lover

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Geckos are masters at sticking to surfaces of all kinds and easily unsticking themselves, too. Inspired by these lizards, a team of engineers has developed a reversible adhesion method for printing electronics on a variety of tricky surfaces such as clothes, plastic and leather.

Gecko feet clinging on glass. Geckos are masters at sticking to surfaces of all kinds and easily unsticking themselves, too. Inspired by these lizards, a team of engineers has developed a reversible adhesion method for printing electronics on a variety of tricky surfaces such as clothes, plastic and leather. (Credit: iStockphoto/Stephan Hoerold)

Researchers from Northwestern University and the University of Illinois at Urbana-Champaign designed a clever square polymer stamp that allows them to vary its adhesion strength. The stamp can easily pick up an array of electronic devices from a silicon surface and move and print them on a curved surface.

The research will be published Sept. 20 by the Proceedings of the National Academy of Sciences (PNAS).

"Our work proposes a very robust method to transfer and print electronics on complex surfaces," said Yonggang Huang, Joseph Cummings Professor of Civil and Environmental Engineering and Mechanical Engineering at Northwestern's McCormick School of Engineering and Applied Science.

Huang, co-corresponding author of the PNAS paper, led the theory and design work at Northwestern. His colleague John Rogers, the Flory-Founder Chair Professor of Materials Science and Engineering at the University of Illinois, led the experimental and fabrication work. Rogers is a co-corresponding author of the paper.

Key to the square and squeezable polymer stamp are four pyramid-shaped tips on the stamp's bottom, one in each corner. They mimic, in a way, the micro- and nano-filaments on the gecko's foot, which the animal uses to control adhesion by increasing or decreasing contact area with a surface.

Pressing the stamp against the electronics causes the soft tips to collapse up against the stamp's body, maximizing the contact area between the stamp and the electronics and creating adhesion. The electronics are picked up in a complete batch, and, with the force removed, the soft tips snap back to their original shape. The electronics now are held in place by just the four tips, a small contact area. This allows the electronics to be easily transferred to a new surface.

"Design of the pyramid tips is very important," Huang said. "The tips have to be the right height. If the tips are too large, they can't pick up the target, and if the tips are too small, they won't bounce back to their shape."

The researchers conducted tests of the stamp and found the changes in contact area allow the stamp's adhesion strength to vary by 1,000 times. They also demonstrated their method can print layers of electronics, enabling the development of a variety of complex devices.

The National Science Foundation and the U.S. Department of Energy supported the work.

The title of the PNAS paper is "Microstructured Elastomeric Surfaces with Reversible Adhesion and Examples of Their Use in Deterministic Assembly by Transfer Printing." In addition to Huang and Rogers, other authors of the paper are Jian Wu (a postdoctoral fellow at Northwestern), Seok Kim, Andrew Carlson, Sung Hun Jin, Anton Kovalsky, Paul Glass, Zhuangjian Liu, Numair Ahmed, Steven L. Elgan, Weiqiu Chen, Placid M. Ferreira and Metin Sitti.

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