Plants of different species can swap chloroplasts, the little cellular factories that capture energy from sunlight, when stems graft together. The surprising discovery may explain why evolutionary histories based on chloroplasts sometimes disagree with those based on other sources of DNA.
“If you had asked me before I did this work, I would have said, ‘This isn’t happening,’” says plant geneticist Pal Maliga of Rutgers University in Piscataway, N.J.
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One day in 2010, Rutgers physicist Vitaly Podzorov watched a store employee showcase a kitchen gadget that vacuum-seals food in plastic. The demo stuck with him. The simple concept – an airtight seal around pieces of food – just might apply to his research: developing flexible electronics using lightweight organic semiconductors for products such as video displays or solar cells.
“Organic transistors, which switch or amplify electronic signals, hold promise for making video displays that bend like book pages or roll and unroll like posters,” said Podzorov. But traditional methods of fabricating a part of the transistor known as the gate insulator often end up damaging the transistor’s delicate semiconductor crystals.
The researchers reported their success in the journal Advanced Materials. In the article, Podzorov and three colleagues describe how a single-crystal organic field effect transistor (OFET) made with this thin polymer gate insulator boosted electrical performance. The researchers further reported that they could remove and reapply membranes to the same crystal several times without degrading its surface.
Organic transistors electrically resemble silicon transistors in computer chips, but they are made of flexible carbon-based molecules that can be printed on sheets of plastic. Silicon transistors are made in rigid, brittle wafers of silicon.
The methods that scientists previously applied to organic transistor fabrication were based on silicon semiconductor processing, explained Podzorov, assistant professor in the Department of Physics and Astronomy, School of Arts and Sciences. These involved high temperatures, high-energy plasmas or chemical reactions, all of which could damage the delicate organic crystal surface and hinder the transistor’s performance.
“People have tendencies to go with something they’ve known for a long time,” he said. “In this case, it doesn’t work right.”
Fabricating single crystal organic field-effect transistors using ultra-thin polymer membrane for a gate insulator. In the upper row, the membrane is stretched over the transistor before vacuum is applied. In the lower row, the vacuum has been applied and the membrant is adhering to the organic crystal. Photos on the right are close-up views of the transistor, with the organic semiconductor crystal in red.
“Our technique takes 10 minutes,” he said. “It should be exciting for students to actually build these devices and immediately see them work, all within one lab session.”
Podzorov was actually trying to solve another problem when he first recalled the food packaging demo. He was thinking about how to protect organic crystals from airborne impurities when his lab shipped samples to collaborating scientists in California and overseas.
“We could place our samples between plastic sheets and pull a vacuum,” he said. “Then I thought, ‘why don’t we try doing this for our gate insulator?’”
Funding for the research was provided by the U. S. Department of Energy and the Rutgers Institute for Advanced Materials and Devices for Nanotechnology. Collaborators in Podzorov’s lab were postdoctoral researchers Hee Taek Yi and Yuanzhen Chen, and undergraduate student Krzysztof Czelen. The department’s machine shop made a custom-designed vacuum chamber for the project.
The National Transportation Safety Board is advising against cell phone use — and even using hands-free devices — while driving. But even some cell phone safety advocates think the recommendation goes too far.
MELISSA BLOCK, HOST:
A federal proposal to ban all texting or talking while driving is drawing audible gasps around the country. The National Transportation Safety Board is urging states to outlaw even hands-free devices, saying they're simply too dangerous.
NPR's Tovia Smith reports.
TOVIA SMITH, BYLINE: They may or may not be in their cars, but there are definitely a lot of people tweeting, texting and talking today about the sweeping ban being proposed by NTSB chair, Deborah Hersman.
DEBORAH HERSMAN: We know that this is going to be very unpopular with some people, but we're not here to win a popularity contest. We're here to do the right thing.
SMITH: Thirty-four states already ban texting while driving. Nine states ban calling on a handheld phone. None go so far as to ban even hands-free calls, but Hersman says a decade of investigating crashes has convinced the agency that even just talking hands-free is a dangerous distraction and should be banned.
HERSMAN: Ask the family members. They will tell you that there have been thousands of deaths that didn't need to happen.
ROB REYNOLDS: We think that it's something that is long overdue and we know that if it were put in place it would save lives.
SMITH: Rob Reynolds' oldest daughter Cady was killed by a distracted driver in 2007. He now runs FocusDriven, a group that believes the only way to drive safely is to drive cell-free. But there are others who see an all-out ban as too drastic. Jeff Larson with the Safe Roads Alliance in Massachusetts says focus should be on getting more states to ban handheld calls. If not, he says, police can't even enforce the laws against texting.
JEFF LARSON: Right now, if you're trying to text on your phone, you can just say, I was dialing a phone number and that's not technically texting. You're allowed to do that. We need to pass a hands-free law, which means that if you're manipulating your phone and police see it, you can get a ticket.
SMITH: Jerry Cibley says a hands-free law might have saved his son, Jordan, who was 18 when he dropped his cell phone on the floor of his car and crashed into a tree trying to pick it up. But Cibley says the argument that even hands-free talking is distracting and needs to be banned is silly.
JERRY CIBLEY: Let's ban car radios, too. I think that would be a good idea. And let's ban passengers and let's ban children. I mean, one of the biggest distractions are children in the backseats. We're not going to outlaw people from having their children.
SMITH: Instead, Cibley says, we require car seats and we use technology to make car seats as safe as possible. There are already devices that can block or limit distracted driving. For example, if a cell phone is determined through GPS to be in a moving vehicle, it could be automatically shut off.
Or Richard Martin at Rutgers University is working on software that would enable a more surgical strike by figuring out whether a phone is being used by a driver or a passenger.
RICHARD MARTIN: The technology's definitely there to bring a hammer down and disable all phone usage or you could be a little more subtle and try to tie it with more environmental factors like how you're driving the vehicle, like weaving, for example, to determine if you should get cut off or something like that.
SMITH: Car makers are developing their own systems; for example, enabling any phone to be operated with voice commands. But they oppose the NTSB's call for an all-out ban. As one of them put it, it's like Prohibition; it's unrealistic and it won't work.
Tovia Smith, NPR News.
New Jersey is a major center for research into the cause and treatment of Tourette syndrome, a neurological disorder known by its "tics," or involuntary vocal and physical behavior, which often are accompanied by other ills like attention deficit disorder, obsessive compulsive disorder, depression and anxiety. Now that research is poised to move into high gear: Rutgers University has been designated the nation's Tourette cell repository by the National Institute of Mental Health.
The full story can be found here.
CAMDEN — How the brain perceives color is one of its more impressive tricks. It is able to keep a stable perception of an object’s color as lighting conditions change.
Sarah Allred, an assistant professor of psychology at Rutgers–Camden, has teamed up with psychologists from the University of Pennsylvania on groundbreaking research that provides new insight into how this works.
Allred conducted the research with Alan L. Gilchrist, a professor of psychology at Rutgers–Newark, and professor David H. Brainard and post-doctoral fellow Ana Radonjic, both of the University of Pennsylvania. Their research will be published in the journal Current Biology.
“Although we recognize easily the colors of objects in many different environments, this is a difficult problem for the brain,” Allred says. “For example, consider just the gray scale that goes from black to white. A white piece of paper in bright sunlight reflects thousands of times more light to the eye than a white piece of paper indoors, but both pieces of paper look white. How does the brain do this?”
The process of seeing an object begins when light reflected off that object hits the light-sensitive structures in the eye. The perception of an object’s lightness (in terms of color shade) depends on the object’s reflectance. Objects that appear lighter reflect a larger percentage of light than those that appear darker.
Allred says the brain processes perceptual differences between black and white objects even when illumination of the object changes. If the brain did not do this, it would fail to distinguish color shade in different light.
In general, white objects reflect about 90 percent of the light that hits them, and black objects reflect about three percent, a ratio of 30-to-1, she explains.
“However, if you look at the intensities of light that enter the eye from a typical scene, like a field of lilies, that ratio is much higher, usually somewhere between 10,000-to-1 and a million-to-1,” Allred says.
This happens because in addition to having objects with different reflectance, real “scenes” also have different levels of illumination. One example might be a shadowed area under a tree. Allred and her research colleagues wanted to determine how the brain maps a large range of light intensity onto a much smaller reflectance range.
One long-time hypothesis is that the brain segments scenes into different regions of illumination and then uses ratio coding to decide what looks white.
To test if this hypothesis was true, the researchers conducted an experiment where participants viewed images that had a very large range of light intensities. Participants were asked to look at a 5x5 checkerboard composed of grayscale squares with random intensities spanning the 10,000-to-1 range. They were asked to report what shades of gray a target square looked like by selecting a match from a standardized gray scale.
If the visual system relied only on ratios to determine surface lightness, then the ratio of checkerboard intensities the participants reported should have had the same ratio as that of the black and white samples on the reflectance scale, about 100-to-1.
Instead, the researchers found that this ratio could be as much as 50 times higher, more than 5,000-to-1.
“This research is important because we have falsified the ratio hypothesis, which is currently the most widely invoked explanation of how we perceive lightness,” Allred says. “We also were able to reject several similar models of lightness. We were able to do this because we measured lightness in such high-range and relatively complex images.”
She continues, “In addition, even though we used behavioral rather than physiological measures, our results provide insight into the neural mechanisms that must underlie the behavioral results.”
A Philadelphia resident, Allred received her undergraduate degree from Brigham Young University and her graduate degree from the University of Washington. She is also conducting research on color memory and perception through a five-year grant from the National Science Foundation.
In a recent study published in the Journal of Neuroscience, Bonnie Firestein, professor of cell biology and neuroscience, in the School of Arts and Sciences, says the new research indicates that increased production of two proteins – cypin and PSD-95 – results in very different outcomes.
While cypin – a protein that regulates nerve cell and neuron branching critical to normal brain functioning -- prevents nerve cells not damaged during the initial stroke from losing the ability to communicate with other cells and halts any secondary brain or neurological damage, PSD-95 accelerates cell destruction and inhibits recovery. Secondary injury from a stroke can occur days or even weeks after the injury and often includes a lack of blood flow, insufficient oxygen, and swelling of the brain.
“We don’t know how or why cypin acts during this process, but what we do know is that cypin helps nerve cells survive,” said Firestein, who first isolated and identified cypin more than a decade ago. Since then, she has been researching how it works in the brain and could be used to treat traumatic brain injury and other serious neurological disorders.
Firestein and her former graduate student Chia-Yi Tseng conducted the laboratory research by putting nerve cells in a dish and creating an “experimental stroke” – mimicking a massive amount of glutamate released, resulting in nerve cells destroyed.
They wanted to determine if anything could be done to stop the secondary damage that occurs after a stroke and discovered that while a greater number of neurons that survived the stroke were spared secondary destruction with increased amounts of cypin, too much PSD-95 resulted in the death of nerve cells not damaged inititally.
“I would hope that this research aids in the development of an effective therapeutic intervention, saving neurons and reducing the long-term effects of stroke and other traumatic brain injuries,” said Firestein.
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