Nanoelectronic Transistor Combined With Biological Machine Could Lead To Better Electronics

Nanoelectronic Transistor Combined With Biological Machine Could Lead To Better Electronics

  9:44:00 PM    Science Lover

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If artificial devices could be combined with biological machines, laptops and other electronic devices could get a boost in operating efficiency.

An artist's representation of a nanobioelectronic device incorporating alamethycin biological pore. In the core of the device is a silicon nanowire (grey), covered with a lipid bilayer (blue). The bilayer incorporates bundles of alamethicin molecules (purple) that form pore channels in the membrane. Transport of protons though these pore channels changes the current through the nanowire. (Credit: Image by Scott Dougherty, LLNL)

Lawrence Livermore National Laboratory researchers have devised a versatile hybrid platform that uses lipid-coated nanowires to build prototype bionanoelectronic devices.

Mingling biological components in electronic circuits could enhance biosensing and diagnostic tools, advance neural prosthetics such as cochlear implants, and could even increase the efficiency of future computers.

While modern communication devices rely on electric fields and currents to carry the flow of information, biological systems are much more complex. They use an arsenal of membrane receptors, channels and pumps to control signal transduction that is unmatched by even the most powerful computers. For example, conversion of sound waves into nerve impulses is a very complicated process, yet the human ear has no trouble performing it.

“Electronic circuits that use these complex biological components could become much more efficient,” said Aleksandr Noy, the LLNL lead scientist on the project.

While earlier research has attempted to integrate biological systems with microelectronics, none have gotten to the point of seamless material-level incorporation.

“But with the creation of even smaller nanomaterials that are comparable to the size of biological molecules, we can integrate the systems at an even more localized level,” Noy said.

To create the bionanoelectronic platform the LLNL team turned to lipid membranes, which are ubiquitous in biological cells. These membranes form a stable, self-healing,and virtually impenetrable barrier to ions and small molecules.

“That's not to mention that these lipid membranes also can house an unlimited number of protein machines that perform a large number of critical recognition, transport and signal transduction functions in the cell,” said Nipun Misra, a UC Berkeley graduate student and a co-author on the paper.

Julio Martinez, a UC Davis graduate student and another co-author added: “Besides some preliminary work, using lipid membranes in nanoelectronic devices remains virtually untapped.”

The researchers incorporated lipid bilayer membranes into silicon nanowire transistors by covering the nanowire with a continuous lipid bilayer shell that forms a barrier between the nanowire surface and solution species.

“This 'shielded wire' configuration allows us to use membrane pores as the only pathway for the ions to reach the nanowire,” Noy said. “This is how we can use the nanowire device to monitor specific transport and also to control the membrane protein.”

The team showed that by changing the gate voltage of the device, they can open and close the membrane pore electronically.

The research appears Aug. 10 in the online version of the Proceedings of the National Academy of Sciences.

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Lasers Generate Underwater Sound: Potential For Naval And Commercial Underwater Acoustic Applications

Lasers Generate Underwater Sound: Potential For Naval And Commercial Underwater Acoustic Applications

  9:34:00 PM    Science Lover

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Scientists at the Naval Research Laboratory are developing a new technology for use in underwater acoustics. The new technology uses flashes of laser light to remotely create underwater sound. The new acoustic source has the potential to expand and improve both Naval and commercial underwater acoustic applications, including undersea communications, navigation, and acoustic imaging.

Scattered light from a 532 nm laser pulse can be seen as it enters the water in the Salt Water Tank Facility, and ionizes a small volume of water for acoustic generation. Air bubblers and controlled water and air temperatures can create ocean-like conditions in the laboratory. (Credit: Image courtesy of Naval Research Laboratory)

Dr. Ted Jones, a physicist in the Plasma Physics Division, is leading a team of researchers from the Plasma Physics, Acoustics, and Marine Geosciences Divisions in developing this acoustic source.

Efficient conversion of light into sound can be achieved by concentrating the light sufficiently to ionize a small amount of water, which then absorbs laser energy and superheats. The result is a small explosion of steam, which can generate a 220 decibel pulse of sound. Optical properties of water can be manipulated with very intense laser light to act like a focusing lens, allowing nonlinear self-focusing (NSF) to take place.

In addition, the slightly different colors of the laser, which travel at different speeds in water due to group velocity dispersion (GVD), can be arranged so that the pulse also compresses in time as it travels through water, further concentrating the light. By using a combination of GVD and NSF, controlled underwater compression of optical pulses can be attained.

The driving laser pulse has the ability to travel through both air and water, so that a compact laser on either an underwater or airborne platform can be used for remote acoustic generation. Since GVD and NSF effects are much stronger in water than air, a properly tailored laser has the ability to travel many hundreds of meters through air, remaining relatively unchanged, then quickly compress upon entry into the water. Atmospheric laser propagation is useful for applications where airborne lasers produce underwater acoustic signals without any required hardware in the water, such as undersea communications from aircraft.

Also, commercially available, high-repetition-rate pulsed lasers, steered by a rapidly movable mirror, can generate arbitrary arrays of phased acoustic sources. On a compact underwater platform with an acoustic receiver, such a setup can rapidly generate oblique-angle acoustic scattering data, for imaging and identifying underwater objects. This would be a significant addition to traditional direct backscattering acoustic data.

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Hydrogen Storage Gets New Hope

Hydrogen Storage Gets New Hope

  9:28:00 PM    Science Lover

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A new method for “recycling” hydrogen-containing fuel materials could open the door to economically viable hydrogen-based vehicles.

Ammonia borane (AB) is a potential hydrogen releasing fuel. In this Los Alamos National Laboratory graphic, the AB would be used on-board the vehicle to run a fuel cell. Once hydrogen is released, the AB could then be regenerated and reused. In the scheme shown,
the recycle of dehydrogenated fuel back into AB would take place off-board the vehicle.
(Credit: Image courtesy of DOE/Los Alamos National Laboratory)

In an article appearing in Angewandte Chemie, Los Alamos National Laboratory and University of Alabama researchers working within the U.S. Department of Energy’s Chemical Hydrogen Storage Center of Excellence describe a significant advance in hydrogen storage science.

Hydrogen is in many ways an ideal fuel for transportation. It is abundant and can be used to run a fuel cell, which is much more efficient than internal combustion engines. Its use in a fuel cell also eliminates the formation of gaseous byproducts that are detrimental to the environment.

For use in transportation, a fuel ideally should be lightweight to maintain overall fuel efficiency and pack a high energy content into a small volume. Unfortunately, under normal conditions, pure hydrogen has a low energy density per unit volume, presenting technical challenges for its use in vehicles capable of travelling 300 miles or more on a single fuel tank—a benchmark target set by DOE.

Consequently, until now, the universe’s lightest element has been considered by some as a lightweight in terms of being a viable transportation fuel.

In order to overcome some of the energy density issues associated with pure hydrogen, work within the Chemical Hydrogen Storage Center of Excellence has focused on using a class of materials known as chemical hydrides. Hydrogen can be released from these materials and potentially used to run a fuel cell. These compounds can be thought of as “chemical fuel tanks” because of their hydrogen storage capacity.

Ammonia borane is an attractive example of a chemical hydride because its hydrogen storage capacity approaches a whopping 20 percent by weight. The chief drawback of ammonia borane, however, has been the lack of energy-efficient methods to reintroduce hydrogen back into the spent fuel once it has been released. In other words, until recently, after hydrogen release, ammonia borane couldn’t be adequately recycled.

Los Alamos researchers have been working with University of Alabama colleagues on developing methods for the efficient recycling of ammonia borane. The research team made a breakthrough when it discovered that a specific form of dehydrogenated fuel, called polyborazylene, could be recycled with relative ease using modest energy input. This development is a significant step toward using ammonia borane as a possible energy carrier for transportation purposes.

“This research represents a breakthrough in the field of hydrogen storage and has significant practical applications,” said Dr. Gene Peterson, leader of the Chemistry Division at Los Alamos. “The chemistry is new and innovative, and the research team is to be commended on this excellent achievement.”

The Chemical Hydrogen Storage Center of Excellence is one of three Center efforts funded by DOE. The other two focus on hydrogen sorption technologies and storage in metal hydrides. The Center of Excellence is a collaboration between Los Alamos, Pacific Northwest National Laboratory, and academic and industrial partners.

Referring to the work described in the Angewandte Chemie article, Los Alamos researcher John Gordon, corresponding author for the paper, stated, “Collaboration encouraged by our Center model was responsible for this breakthrough. At the outset there were myriad potential reagents with which to attempt this chemistry.”

“The predictive calculations carried out by University of Alabama professor Dave Dixon’s group were crucial in guiding the experimental work of Los Alamos postdoctoral researcher Ben Davis,” Gordon added. “The excellent synergy between these two groups clearly enabled this advance.”

The research team currently is working with colleagues at The Dow Chemical Company, another Center partner, to improve overall chemical efficiencies and move toward large-scale implementation of hydrogen-based fuels within the transportation sector.

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That Late-night Snack: Worse Than You Think

That Late-night Snack: Worse Than You Think

  9:12:00 PM    Science Lover

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Eat less, exercise more. Now there is new evidence to support adding another "must" to the weight-loss mantra: eat at the right time of day.

Eating at irregular times -- the equivalent of the middle of the night for humans,
when the body wants to sleep -- influences weight gain, a new study has found.
(Credit: iStockphoto/Curt Pickens)

A Northwestern University study has found that eating at irregular times -- the equivalent of the middle of the night for humans, when the body wants to sleep -- influences weight gain. The regulation of energy by the body's circadian rhythms may play a significant role. The study is the first causal evidence linking meal timing and increased weight gain.

"How or why a person gains weight is very complicated, but it clearly is not just calories in and calories out," said Fred Turek, professor of neurobiology and physiology in the Weinberg College of Arts and Sciences and director of the Center for Sleep and Circadian Biology. "We think some factors are under circadian control. Better timing of meals, which would require a change in behavior, could be a critical element in slowing the ever-increasing incidence of obesity."

The findings could have implications for developing strategies to combat obesity in humans, as the United States and the world battle what has been called an "obesity epidemic." More than 300 million adults worldwide are obese, including more than a third of American adults.

Details of the obesity study, which was led by Turek, will be published online Sept. 3 by the journal Obesity.

"One of our research interests is shift workers, who tend to be overweight," said lead author Deanna M. Arble, a doctoral student in Turek's lab. "Their schedules force them to eat at times that conflict with their natural body rhythms. This was one piece of evidence that got us thinking -- eating at the wrong time of day might be contributing to weight gain. So we started our investigation with this experiment."

Simply modifying the time of feeding alone can greatly affect body weight, the researchers found. Mice that were fed a high-fat diet during normal sleeping hours gained significantly more weight (a 48 percent weight increase over their baseline) than mice eating the same type and amount of food during naturally wakeful hours (a 20 percent increase over their baseline). There was no statistical difference between the two groups regarding caloric intake or the amount of activity.

Over a period of six weeks, both groups of mice were allowed to eat as much high-fat diet as they wanted during their daily 12-hour feeding phase. (Much like many humans, mice have a preference for high-fat food.) Since mice are nocturnal, the 12-hour feeding phase was during the day for those fed during normal sleeping hours and during the night for those fed during naturally wakeful hours. Food was not provided during the other 12 hours of their day.

Our circadian clock, or biological timing system, governs our daily cycles of feeding, activity and sleep, with respect to external dark and light cycles. Recent studies have found the body's internal clock also regulates energy use, suggesting the timing of meals may matter in the balance between caloric intake and expenditure.

The researchers next plan to investigate the molecular mechanisms behind their observation that eating at the "wrong" time can lead to weight gain.

In addition to Turek and Arble, other authors of the paper are Joseph Bass, Aaron D. Laposky and Martha H. Vitaterna, all from Northwestern.

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'Achilles' Heel' In Y Chromosome Linked To Sex Disorders

'Achilles' Heel' In Y Chromosome Linked To Sex Disorders

  8:52:00 PM    Science Lover

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The unique mechanism behind the evolutionary survival of the human Y chromosome may also be responsible for a range of sex disorders, from failed sperm production to sex reversal to Turner Syndrome.

A tug of war between nascent daughter cells can snap isodicentric in two, leading to its loss during development of the fetus. (Credit: Tom DiCesare/Whitehead)

Roughly six years ago, David Page's lab at Whitehead Institute for Biomedical Research reported the discovery of eight large areas of mirror-imaged genetic sequences, or palindromes, along the Y chromosome. Because the Y chromosome essentially has no partner with which to swap genes, a process that between ordinary chromosome pairs leads to genetic diversity and the exchange of good genes for damaged ones, it relies on its own palindromes to swap genes with itself. The Y, as it turns out, folds itself in the middle of palindromic regions, thereby pairing identical sequences to allow for potentially beneficial genetic exchange.

At the time, the finding provided explanation for why, despite much-heralded reports to the contrary, the Y chromosome is not doomed to extinction. Now, the Page lab has discovered that the Y's process of self-preservation can randomly go awry, with considerable clinical consequence.

"This is the sequel to the Y chromosome palindrome story," says Page, Whitehead Institute Director and a Howard Hughes Medical Institute investigator.

The latest chapter of the story, whose conclusion is published in the September 4 issue of Cell, began with the intriguing hypothesis that perhaps the Y's process of self-recombination can inadvertently turn the entire chromosome into a palindrome—literally, a mirror-image of itself. The result would be a so-called isodicentric Y chromosome (idicY), an abnormal structure with, as the name implies, two centromeres.

"We began to think seriously about the centromeres and the activity around them. Two centromeres render the chromosome susceptible to damage," says Julian Lange, first author of the Cell paper and a former graduate student in the Page lab. Because of the Y chromosome's well known roles in sex determination and male fertility, Lange began to speculate about the potential clinical impact of the transmission of an idicY during fertilization.

"Because the Y chromosome is not essential to an individual's survival, these isodicentric Ys can persist," says Lange, who, after completing this research at Whitehead, became a postdoctoral fellow at Memorial Sloan-Kettering Cancer Center. "They can be found in the population."

And Lange found them, in the DNA samples of 51 patients screened from a field of nearly 2400 individuals who had come under study over the course of many years because of failed sperm production, structurally abnormal Y chromosomes, or sex reversal. Through sophisticated genetic analysis, it became clear that idicYs were responsible for spermatogenic failure in many of the male patients.

However, 18 of the 51 patients were anatomically female—despite having two copies of the male-determining SRY gene on their idicY chromosomes. Lange and Page began to hypothesize that the feminization they had identified was related to the instability of the idicYs themselves. Suspecting that the level of instability of an idicY increases with the size of the chromosome, they looked for a connection and found something somewhat paradoxical: the larger the Y chromosome, the greater the likelihood of sex reversal.

"We had predicted this correlation, which relates to the overall distance between the centromeres," says Page. "But when we confirmed it with the patient data, we were blown away."

Page believes that this new model for the formation of idicY chromosomes, coupled with the size-instability correlation, suggests a causal link to Turner syndrome, a chromosomal abnormality in girls or women, characterized by the lack of one sex chromosome. Turner syndrome affects an estimated 1 in 2500 females. Page won't yet speculate as to what percentage of Turner syndrome could be caused by this palindrome-to-palindrome recombination, but he does think it's significant.

David Page's primary affiliation is with Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also a Howard Hughes Medical Institute investigator and a professor of biology at Massachusetts Institute of Technology.

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Human Brain Could Be Replicated In 10 Years, Researcher Predicts

Human Brain Could Be Replicated In 10 Years, Researcher Predicts

  10:54:00 AM    Science Lover

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A model that replicates the functions of the human brain is feasible in 10 years according to neuroscientist Professor Henry Markram of the Brain Mind Institute in Switzerland. "I absolutely believe it is technically and biologically possible. The only uncertainty is financial. It is an extremely expensive project and not all is yet secured."

Activity in the brain's neocortex is tightly controlled by
inhibitory neurons shown here which prevent epilepsy.
(Credit: Blue Brain Project; Ecole Polytechnique Federale de Lausanne)

The apparent complexity of the human mind is not a barrier to building a 'replica' brain claims Professor Markram. "The brain is of course extremely complex because it has trillions of synapses, billions of neurons, millions of proteins, and thousands of genes. But they are still finite in number. Today's technology is already highly sophisticated and it allows us to reverse engineer the brain rapidly." An example of the capability already in place is that today's robots can do screenings and mappings tens of thousands of times faster than human scientists and technicians.

Another hurdle on the path to a model human brain is that 100 years of neuroscience discovery has led to millions of fragments of data and knowledge that have never been brought together and exploited fully. "Actually no one even knows what we already understand about the brain," says Professor Markram. "A model would serve to bring this all together and then allow anyone to test whatever theory you want about the brain. The biggest challenge is to understand how electrical-magnetic-chemical patterns in the brain convert into our perception of reality. We think we see with our eyes, but in fact most of what we 'see' is generated as a projection by your brain. So what are we actually looking at when we look at something 'outside' of us?"

For Professor Markram, the most exciting part of his research is putting together the hundreds of thousands of small pieces of data that his lab has collected over the past 15 years, and seeing what a microcircuit of the brain looks like. "When we first switched it on it already started to display some interesting emergent properties. But this is just the beginning because we know now that it is possible to build it. As we progress we are learning about design secrets of our brains which were unimaginable before. In fact the brain uses some simple rules to solve highly complex problems and extracting each of these rules one by one is very exciting. For example we have been surprised at finding simple design principles that allow billions of neurons to connect to each other. I think we will understand how the brain is designed and works before we have finished building it."

The opportunities for this neuroscience research challenge are immense explains Professor Markram: "A brain model will sit on a massive supercomputer and serve as a kind of educational and diagnostic service to society. As the industrial revolution in science progresses we will generate more data than anyone can track or any computer can store, so models that can absorb it are simply unavoidable. It is also essential to build models when it comes to treating brain diseases affecting around two billion people. At present, there is no brain disease for which we really understand what has gone wrong in the processing, in the circuits, neurons or synapses. It is also important if we are to replace the need for the millions of animal experiments each year for brain research."

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Mice Can Eat 'Junk' And Not Get Fat: Researchers Find Gene That Protects High-fat-diet Mice From Obesity

Mice Can Eat 'Junk' And Not Get Fat: Researchers Find Gene That Protects High-fat-diet Mice From Obesity

  10:47:00 AM    Science Lover

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University of Michigan researchers have identified a gene that acts as a master switch to control obesity in mice. When the switch is turned off, even high-fat-diet mice remain thin.

Both mice were fed high-fat diets for several months.
Deleting the IKKE gene in the mouse on the left protected it
against the weight gain apparent in the mouse on the right.
(Credit: Photo by Scott Galvin, U-M Photo Services)

Deleting the gene, called IKKE, also appears to protect mice against conditions that, in humans, lead to Type 2 diabetes, which is associated with obesity and is on the rise among Americans, including children and adolescents.

If follow-up studies show that IKKE is tied to obesity in humans, the gene and the protein it makes will be prime targets for the development of drugs to treat obesity, diabetes and complications associated with those disorders, said Alan Saltiel, the Mary Sue Coleman Director of the U-M Life Sciences Institute.

"We've studied other genes associated with obesity – we call them 'obesogenes' – but this is the first one we've found that, when deleted, stops the animal from gaining weight," said Saltiel, senior author of a paper to be published in the Sept. 4 edition of the journal Cell.

"The fact that you can disrupt all the effects of a high-fat diet by deleting this one gene in mice is pretty interesting and surprising," he said.

Obesity is associated with a state of chronic, low-grade inflammation that leads to insulin resistance, which is usually the first step in the development of Type 2 diabetes. In the Cell paper, Saltiel and his colleagues show that deleting, or "knocking out," the IKKE gene not only protected high-fat-diet mice from obesity, it prevented chronic inflammation, a fatty liver and insulin resistance, as well.

The high-fat-diet mice were fed a lard-like substance with 45 percent of its calories from fat. Control mice were fed standard chow with 4.5 percent of its calories from fat. The dietary regimen began when the mice were 8 weeks old and continued for 14 to 16 weeks.

The gene IKKE produces a protein kinase also known as IKKE. Protein kinases are enzymes that turn other proteins on or off. The IKKE protein kinase appears to target proteins which, in turn, control genes that regulate the mouse metabolism.

When the high-fat diet is fed to a normal mouse, IKKE protein-kinase levels rise, the metabolic rate slows, and the animal gains weight. In that situation, the IKKE protein kinase acts as a brake on the metabolism.

Knockout mice placed on the high-fat diet did not gain weight, apparently because deleting the IKKE gene releases the metabolic brake, allowing it to speed up and burn more calories, instead of storing those calories as fat.

"The knockout mice are not exercising any more than the control mice used in the study. They're just burning more energy," Saltiel said. "And in the process, they're generating a little heat, as well – their body temperature actually increases a bit."

Saltiel's team is now searching for small molecules that block IKKE protein-kinase activity. IKKE inhibitors could become candidates for drug development.

"If you find an inhibitor of this protein kinase, you should be able to obtain the same effect as knocking out the gene. And that's the goal," Saltiel said. If successful candidates are identified and drug development is pursued, a new treatment for obesity and diabetes is likely a decade away, he said.

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First author of the Cell paper is Shian-Huey Chiang of the Life Sciences Institute. Co-authors are U-M researchers Merlijn Bazuine, Carey Lumeng, Lynn Geletka, Jonathan Mowers, Nicole White, Jing-Tyan Ma, Jie Zhou, Nathan Qi, Dan Westcott and Jennifer Delproposto. Timothy Blackwell and Fiona Yull of the Vanderbilt University School of Medicine also are co-authors.

The research was funded by the National Institutes of Health and the American Diabetes Association. All animal use was conducted in compliance with the Institute of Laboratory Animal Research's Guide for the Care and Use of Laboratory Animals and was approved by the University Committee on Use and Care of Animals at the University of Michigan.

Related links:

Life Sciences Institute:

http://www.lsi.umich.edu

Saltiel Lab:

http://www.lsi.umich.edu/facultyresearch/labs/saltiel

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World-first Swine-flu Vaccine Trial Reveals One Dose Provides 'Strong Immune Response'

World-first Swine-flu Vaccine Trial Reveals One Dose Provides 'Strong Immune Response'

  8:47:00 AM    Science Lover

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Results from the first swine-flu vaccine trials taking place in Leicester reveal a strong immune response after just one dose.

Image by AJC1 via Flickr

The pilot study, run by the University of Leicester and Leicester Hospitals, was trialled with 100 healthy volunteers, aged between 18 and 50.

Dr Iain Stephenson, who led the trial at the Leicester Royal Infirmary, said: “The clinical trial of Novartis MF59-adjuvanted cell-based A (H1N1) vaccine indicates that the “swine flu” vaccine elicits a strong immune response and is well-tolerated.

“Results showed that the serum antibody responses were highest among subjects who received two doses of vaccine, however a single vaccine dose also induced responses associated with protection against influenza.

“The findings showed that it is possible to induce protective antibody against A(H1N1) infection within two weeks of administration of a single low-dose adjuvanted vaccine.”

Non-adjuvanted formulations were not evaluated in this part of the study and will be evaluated shortly

The trial evaluated the tolerability and immunogenicity of the vaccine, and tested different schedules of vaccination, in terms of time between vaccinations. The vaccine schedule was one or two doses of 7.5μg MF-59 adjuvanted surface-antigen A/California/2009 vaccine derived from cell-culture.

Dr. Stephenson, of the Department of Infection, Immunity and Inflammation at the University of Leicester is a clinical senior lecturer at the University, and a consultant in infectious diseases at the University Hospitals of Leicester NHS Trust. He said: “The aim of the trial was to find out how many doses and what type of vaccine is needed to give protection. These initial results should help to plan vaccination campaigns in the autumn, including doses and timings. We concluded that the MF59-adjuvanted A(H1N1) vaccine of low antigen content was well tolerated and generated antibody responses associated with protection against influenza, even after a single dose.”

“The results suggest that one vaccine dose may be sufficient to protect against the A(H1N1) swine flu, rather than two. Larger trials are already underway around the world. Timings on when the vaccine will be available to governments will depend on the results of these clinical trials, and approvals by regulatory authorities’’

The research found the vaccine is well tolerated with pain at the injection site the most frequent adverse event.

Additional pivotal trials with both cell culture and traditional egg based vaccines under way around the world that will include more than 6000 adults and children.

Previous research had indicated that two doses of the vaccine would be needed against swine flu.

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Better Test To Detect DNA For Diagnosing Disease, Investigating Crimes

Better Test To Detect DNA For Diagnosing Disease, Investigating Crimes

  8:10:00 AM    Science Lover

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Researchers in Singapore are reporting development of a new electronic sensor that shows promise as a faster, less expensive, and more practical alternative than tests now used to detect DNA. Such tests are done for criminal investigation, disease diagnosis, and other purposes. The new lab-on-a-chip test could lead to wider, more convenient use of DNA testing, the researchers say. Their study is scheduled for the Sept. 2 issue of the Journal of the American Chemical Society.

In the new study, Zhiqiang Gao and colleagues note that current methods for detecting DNA involve the used of the polymerase chain reaction (PCR). This technique "amplifies" or makes multiple copies of trace amounts of DNA, much as a photocopier produces multiple copies of documents, in order to detect the genetic material more easily. The amplification step is one reason why tests involving PCR can be too expensive, cumbersome, and imprecise for wider use.

The researchers describe development of a so-called "nanogap sensor" that appears to overcome those obstacles. The process uses a pair of micro-sized metal electrodes separated by a nanogap, 1/50,000 the width of a human hair, in combination with special chemical probes, to capture tiny segments of DNA. The newly formed "circuit" then translates the presence of DNA into an electrical signal so that it can be measured by a computer. In laboratory tests, the sensor showed "excellent" sensitivity at detecting trace amounts of human DNA and may eliminate the need for DNA amplification altogether, the researchers say.

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Believing Is Seeing: Thoughts Color Perception -- Implications From Everyday Misunderstandings To Eyewitness Memory

Believing Is Seeing: Thoughts Color Perception -- Implications From Everyday Misunderstandings To Eyewitness Memory

  7:58:00 AM    Science Lover

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Folk wisdom usually has it that "seeing is believing," but new research suggests that "believing is seeing," too – at least when it comes to perceiving other people's emotions.

Researchers showed experimental participants still photographs of faces computer-morphed to express ambiguous emotion and instructed them to think of these faces as either angry or happy. Once an ambiguous look was interpreted, it biased subsequent perception. (Credit: Courtesy of Piotr Winkielman, UC San Diego)

An international team of psychologists from the United States, New Zealand and France has found that the way we initially think about the emotions of others biases our subsequent perception (and memory) of their facial expressions. So once we interpret an ambiguous or neutral look as angry or happy, we later remember and actually see it as such.

The study, published in the September issue of the journal Psychological Science, "addresses the age-old question: 'Do we see reality as it is, or is what we see influenced by our preconceptions?'" said coauthor Piotr Winkielman, professor of psychology at the University of California, San Diego. "Our findings indicate that what we think has a noticeable effect on our perceptions."

"We imagine our emotional expressions as unambiguous ways of communicating how we're feeling," said coauthor Jamin Halberstadt, of the University of Otago in New Zealand, "but in real social interactions, facial expressions are blends of multiple emotions – they are open to interpretation. This means that two people can have different recollections about the same emotional episode, yet both be correct about what they 'saw.' So when my wife remembers my smirk as cynicism, she is right: her explanation of the expression at the time biased her perception of it. But it is also true that, had she explained my expression as empathy, I wouldn't be sleeping on the couch."

"It's a paradox," Halberstadt added. "The more we seek meaning in other emotions, the less accurate we are in remembering them."

The researchers point out that implications of the results go beyond everyday interpersonal misunderstandings – especially for those who have persistent or dysfunctional ways of understanding emotions, such as socially anxious or traumatized individuals. For example, the socially anxious have negative interpretations of others' reactions that may permanently color their perceptions of feelings and intentions, perpetuating their erroneous beliefs even in the face of evidence to the contrary. Other applications of the findings include eyewitness memory: A witness to a violent crime, for example, may attribute malice to a perpetrator – an impression which, according to the researchers, will influence memory for the perpetrator's face and emotional expression.

The researchers showed experimental participants still photographs of faces computer-morphed to express ambiguous emotion and instructed them to think of these faces as either angry or happy. Participants then watched movies of the faces slowly changing expression, from angry to happy, and were asked to find the photograph they had originally seen. People's initial interpretations influenced their memories: Faces initially interpreted as angry were remembered as expressing more anger than faces initially interpreted as happy.

Even more interesting, the ambiguous faces were also perceived and reacted to differently. By measuring subtle electrical signals coming from the muscles that control facial expressions, the researchers discovered that the participants imitated – on their own faces – the previously interpreted emotion when viewing the ambiguous faces again. In other words, when viewing a facial expression they had once thought about as angry, people expressed more anger themselves than did people viewing the same face if they had initially interpreted it as happy.

Because it is largely automatic, the researchers write, such facial mimicry reflects how the ambiguous face is perceived, revealing that participants were literally seeing different expressions.

"The novel finding here," said Winkielman, of UC San Diego, "is that our body is the interface: The place where thoughts and perceptions meet. It supports a growing area of research on 'embodied cognition' and 'embodied emotion.' Our corporeal self is intimately intertwined with how – and what – we think and feel."

Also coauthors on the study are Paula Niedenthal and Nathalie Dalle, both at the Universite Blaise Pascall, Clermont-Ferrand, France.

The research was supported by a National Science Foundation grant to Winkielman and Niedenthal and a University of Otago Research Grant to Halberstadt.

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