Scientists make advances in neuroscience and vision research

 
This is a confocal micrograph of a single cone bipolar cell (green) that extends its dendrites to receive synaptic inputs (red dots) from a local population of cone photoreceptor terminals (violet). Credit: Sammy Lee

Thanks to a new study of the retina, scientists at UC Santa Barbara have developed a greater understanding of how the nervous system becomes wired during early development.

The findings reflect the expansion of developmental neurobiology and vision research at UCSB. The work is described in a recent publication of the Journal of Neuroscience.

The research team examined the connectivity of nerve cells, called neurons, in mice. Neurons communicate with one another via synapses where the dendrites and axon terminals of different cells form contacts. This is where nerve signals are transmitted from one neuron to another.

Scientists have understood for some time how neuronal activation at developing synapses contributes to the patterns of connectivity observed in maturity, explained Ben Reese, senior author and professor in UCSB's Neuroscience Research Institute and the Department of Psychological & Brain Sciences.

Incoming activity plays a critical role in sculpting neuronal form and the elaboration of synaptic connections. The new research shows, by contrast, how relationships between neighboring cells of the same type independently regulate neuronal size and connectivity.

The researchers circumvented the difficulty of visualizing the three-dimensional relationships between neurons within the brain by working within the retina. The retina is an outgrowth of the brain during embryonic development, and is a precisely layered structure in which the cells, their dendrites and their axons are restricted to discrete strata. "This makes the visualization and analysis of neuronal morphology and connectivity far simpler," said Reese.

The scientists used two genetically modified mouse models to modulate the density of one particular type of retinal neuron, a class of cone bipolar cell. Cone bipolar cells relay information from the population of cone photoreceptors to the retinal ganglion cells. The latter are neurons that in turn project information to locations within the brain where further visual processing of the retinal image takes place.

The lead author on the study, Sammy Lee, was a postdoctoral researcher working in Reese's lab and supported by a C.J. Martin National Health & Medical Research Council fellowship from Australia during the course of the study. Lee labeled individual cone bipolar cells with a fluorescent dye through a new microinjection procedure developed by Patrick Keeley, a graduate student in the Reese lab.

"What Dr. Lee has shown is that cone bipolar cells modulate the size of their dendritic fields (branched extensions of the neuron) in association with the local density of like-type neurons," said Reese. "One line of mice has conspicuously fewer cone bipolar cells, each now with a larger dendritic territory, while the other line shows heightened densities and correspondingly smaller dendritic fields."

Other studies have suggested such homotypic (like-type) modulation of dendritic field size, but the current study directly shows this modulation following genetic manipulation of neuronal density, according to Reese.

Additionally, the researchers found that connectivity with the afferent population of cone photoreceptors is impacted directly, with the larger dendritic fields being innervated by more cones, and the smaller dendritic fields connecting with fewer cones. At any individual cone, the number of dendritic endings associating with that cone was not observed to change, so that the total number of connections made by a cone bipolar cell was remarkably plastic, defined solely by the number of cone contacts formed.

"This developmental plasticity in dendritic growth and synapse number may be well-suited to ensure uniform coverage and connectivity between two populations of neurons –– afferents and their targets –– when the number of cells in each population is specified independently," said Reese.

Other studies from Reese's lab, recently reported in The Proceedings of the National Academy of Sciences and Investigative Ophthalmology and Visual Science, showed how neuronal number is tightly specified genetically, yet is highly variable between different strains of mice. "Wiring together two populations, each of which may vary nearly two-fold in size, yet independent of each other, might best be served by such homotypic plasticity during early development," he said.

Studies like these may prove relevant for re-establishing connectivity following nerve cell re-specification or replacement in degenerative diseases, particularly as advances in stem cell biology make this an increasing possibility, said Reese.

Provided by University of California - Santa Barbara

"Scientists make advances in neuroscience and vision research." December 6th, 2011. http://medicalxpress.com/news/2011-12-scientists-advances-neuroscience-vision.html

 

Posted by
Robert Karl Stonjek

Tiger Woods' superstar status hobbled the competition

Tiger Woods's phenomenal talent won him a ton of golf tournaments. But an article published in the latest issue of the Journal of Political Economy shows he has something else going for him: his superstar status hobbles the competition.

According to research by Northwestern University economist Jennifer Brown, when Woods played in a tournament during his heyday, the other golfers' scores were substantially worse compared to tournaments where Woods did not play. Instead of raising their game to play the superstar, golfers facing Woods tended to wilt.

Brown's research is designed to investigate the dynamics of tournament-style competition within companies. For example, a company may reward its top monthly salesperson with some extra money or a prize -- the idea being that competition increases everybody's effort. But what if one salesperson seems to win every month? The others might slack off, knowing they have little chance to take the prize.

Brown's analysis of Woods supports the idea that superstars can be a disincentive to the competition.

She looked at PGA scores from 1999 to 2010 -- years that included Tiger's prime. She found that when Woods played in a tournament, other players shot nearly a full stroke higher -- which in golf means worse. The effect was strongest among the top-ranked players, who would be in direct competition with Woods for the highest payouts.

The poorer play was not due to players attempting longer, riskier shots to try to keep up with Tiger, Brown found. If that were the case, we'd expect to see players hit more eagles (two strokes better than par) and more double bogeys (two strokes worse than par) when playing against Woods, reflecting a high-risk, high-reward strategy. But that's not the case, Brown's research shows. There were significantly fewer eagles and double bogeys when Woods played.

So how much has Woods benefitted from the superstar effect?

"My calculations suggest that Woods's PGA Tour earnings would have fallen from $54.5 million to $48.4 million between 1999 and 2006 had his competitors' performance not suffered the superstar effect,' Brown writes. "By my estimates, Woods pocketed nearly $6 million in additional earnings because of the reduced effort of other golfers -- prize money that would otherwise have been distributed to other players in the field."

The results have implications for businesses that use internal competition to drive incentives, Brown says.

"For example, sales managers and law firms should be aware of the impact of introducing a superstar associate on the cohort's overall performance," she writes.

More information: Jennifer Brown, "Quitters Never Win: The (Adverse) Incentive Effects of Competing with Superstars." Journal of Political Economy 119:5.

Provided by University of Chicago

"Tiger Woods' superstar status hobbled the competition." December 6th, 2011. http://www.physorg.com/news/2011-12-tiger-woods-superstar-status-hobbled.html

 

Posted by
Robert Karl Stonjek

A Pendant and Vibhuti Manifested From Shirdi India

Fluorescent Protein Lights Up the Inner Workings of the Brain

Light up: Applying voltage to the neurons shown here caused an increase in fluorescence.
Adam Cohen, Harvard University

BIOMEDICINE

Fluorescent Protein Lights Up the Inner Workings of the Brain

The advance offers a nontoxic way to study how the organ works, and how disease impairs it.

• BY ERICA WESTLY

Audio »

Interactions between neurons involve both chemical and electrical signaling. For decades, neuroscientists have searched for a noninvasive way to measure the electrical component. Achieving this could make it easier to study how the brain works, and how neurological disease impairs its functioning.

One promising approach is tracking neuronal electrical activity with fluorescence, which can be integrated into cells fairly easily through genetics or by being attached to antibodies, but which can be toxic and slow to work. Last week, researchers introduced a new candidate—a fluorescent protein from a Dead Sea microbe—that appears to be better equipped for the challenge.

The protein, called archaerhodopsin-3, or Arch, was discovered more than 10 years ago, but scientists are just now starting to realize its potential as a research tool. In a study published last year, researchers used light to trigger an electrical response from Arch that silenced overactive neurons—an approach that could lead to new therapeutics for epilepsy and other seizure disorders.

In this study, the researchers took the opposite tack and used electricity to elicit changes in Arch's fluorescence. The approach could lead to more accurate methods for recording electrical signals from the brain.

The results, published in Nature Methods, indicate that Arch could be the noninvasive voltage sensor neuroscientists have been looking for: It's not toxic to cells, and it's sensitive and fast enough to pick up the rapid electrical changes that accompany neuronal activity.

"It looks order of magnitudes better than any of the other optical imaging methods I've seen before," says Darcy Peterka, a neuroscientist at Columbia University who was not involved with the study.

The standard method for recording electrical activity in neurons in cell culture—which involves sticking an electrode into the cell—remains the most accurate for measuring voltage at a single point in the cell. But puncturing a neuron with an electrode eventually kills it, whereas Arch would let researchers follow the electrical signal as it propagates throughout the cell. It would also allow researchers to record from the same cell again and again, allowing for long-term experiments that would not be possible with the standard method.

"It really depends on what scientific questions you're trying to answer," says Adam Cohen, a biophysics researcher at Harvard University and the lead author of the new study.

The study was conducted in cultured mouse neurons, but Cohen and his colleagues plan to use Arch to measure neuronal activity in live animals, starting with simple organisms, such as the zebrafish and the worm C. elegans. One advantage of these animals is that they're transparent, making it easy to see the fluorescent signal through a microscope.

Arch could also prove useful for imaging electrical signals in the mammalian brain, especially for experiments in mice, which could be genetically engineered to express the protein in specific neurons or at specific times in development, for example.

The challenge of transferring the approach to animals is making sure the fluorescent signal stays strong and consistent. "In the living brain, light gets absorbed—for example, by blood—so you lose light," says Ed Boyden, the researcher at MIT who led the study that used Arch to silence neurons.

The fluorescence given off by Arch also isn't as bright as some of the other available dyes, but its low toxicity makes this less of a concern, because researchers could compensate by using higher concentrations. "The fact that they got it to work well in mouse neurons bodes well," says Peterka.

Gasoline Fuel Cell Would Boost Electric Car Range

Gas guzzler: The fuel cell developed at the University of Maryland.
University of Maryland

ENERGY

Gasoline Fuel Cell Would Boost Electric Car Range

The advanced fuel cell could eliminate range anxiety and make electric cars more practical, while keeping carbon-dioxide emissions low.

• BY KEVIN BULLIS

Audio »

If you want to take an electric car on a long drive, you need a gas-powered generator, like the one in the Chevrolet Volt, to extend its range. The problem is that when it's running on the generator, it's no more efficient than a conventional car. In fact, it's even less efficient, because it has a heavy battery pack to lug around.

Now researchers at the University of Maryland have made a fuel cell that could provide a far more efficient alternative to a gasoline generator. Like all fuel cells, it generates electricity through a chemical reaction, rather than by burning fuel, and can be twice as efficient at generating electricity as a generator that uses combustion.

The researchers' fuel cell is a greatly improved version of a type that has a solid ceramic electrolyte, and is known as a solid-oxide fuel cell. Unlike the hydrogen fuel cells typically used in cars, solid-oxide fuel cells can run on a variety of readily available fuels, including diesel, gasoline, and natural gas. They've been used for generating power for buildings, but they've been considered impractical for use in cars because they're far too big and because they operate at very high temperatures—typically at about 900 ⁰C.

By developing new electrolyte materials and changing the cell's design, the researchers made a fuel cell that is much more compact. It can produce 10 times as much power, for its size, as a conventional one, and could be smaller than a gasoline engine while producing as much power.

The researchers have also lowered the temperature at which the fuel cell operates by hundreds of degrees, which will allow them to use cheaper materials. "It's a huge difference in cost," says Eric Wachsman, director of the University of Maryland Energy Research Center, who led the research. He says the researchers have identified simple ways to improve the power output and reduce the temperature further still, using methods that are already showing promising results it the lab. These advances could bring costs to a point that they are competitive with gasoline engines. Wachsman says he's in the early stages of starting a company to commercialize the technology.

Wachsman's fuel cells currently operate at 650 ⁰C, and his goal is to bring that down to 350 ⁰C for use in cars. Insulating the fuel cells isn't difficult since they're small—a fuel cell stack big enough to power a car would only need to be 10 centimeters on a side. High temperatures are a bigger problem because they make it necessary to use expensive, heat-resistant materials within the device, and because heating the cell to operating temperatures takes a long time. By bringing the temperatures down, Wachsman can use cheaper materials and decrease the amount of time it takes the cell to start.                              

Even with these advances, the fuel cell wouldn't come on instantly, and turning it on and off with every short trip in the car would cause a lot of wear and tear, reducing its lifetime. Instead, it would be paired with a battery pack, as a combustion engine is in the Volt, Wachsman says. The fuel cell could then run more steadily, serving to keep the battery topped without providing bursts of acceleration.

The researchers achieved their result largely by modifying the solid electrolyte material at the core of a solid-oxide fuel cell. In fuel cells on the market, such as one made by Bloom Energy, the electrolyte has to be made thick enough to provide structural support. But the thickness of the electrolyte limits power generation. Over the last several years, researchers have been developing designs that don't require the electrolyte to support the cell so they can make the electrolyte thinner and achieve high power output at lower temperatures. The University of Maryland researchers took this a step further by developing new multilayered electrolytes that increase the power output still more.

The work is part of a larger U.S. Department of Energy effort, over the past decade, to make solid-oxide fuel cells practical. The first fruits of that effort likely won't be fuel cells in cars—so far, Wachsman has only made relatively small fuel cells, and significant engineering work remains to be done. The first applications of solid oxide fuels in vehicles may be on long-haul trucks with sleeper cabs.

Equipment suppliers such as Delphi and Cummins are developing fuel cells that can power the air conditioners, TVs, and microwaves inside the cabs, potentially cutting fuel consumption by 85 percent compared to idling the truck's engine. The Delphi system also uses a design that allows for a thinner electrolyte, but it operates at higher temperatures than Wachsman's fuel cell. The fuel cell could be turned on Monday, and left to run at low rates all week and still get the 85 percent reduction. Delphi has built a prototype and plans to demonstrate its system on a truck next year.

Nano Paint Could Make Airplanes Invisible to Radar

A nanotube coating would allow a plane to absorb a radar beam, making it undetectable.

• BY KATHERINE BOURZAC

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A new nanostructured coating could be used to make paints for stealth aircraft that can't be seen at night and that are undetectable by radar at any time of day. The coating, made of carbon nanotubes, can be used to cloak an object in utter darkness, making it indistinguishable from the night sky.

Carbon nanotubes have many superlative properties, including excellent strength and electrical conductivity. They are also the blackest known material. The long straws of pure carbon, each just a few nanometers in diameter, absorb a broad spectrum of light—from radio waves through visible light through the ultraviolet—almost perfectly. Researchers are taking advantage of this perfect absorbance in highly sensitive imaging sensors and other prototype devices.

L. Jay Guo, professor of electrical engineering and computer science at the University of Michigan, realized it could be useful as a kind of camouflage. Stealth aircraft, he notes, are often painted black or dark blue to hide them from view.

Guo's group grew sparse forests of vertical carbon nanotubes on the surface of various three-dimensional objects, including a silicon wafer patterned with a tiny tank. The nanotubes make the objects appear wholly flat and black, and they disappear against a black background. The nanotube-coated things neither reflect nor scatter light.

This effect works, Guo says, because the nanotubes are perfectly absorbing and because when they are grown with some space between them, as in his experiments, their index of refraction is nearly identical to that of the surrounding air. This means that light won't scatter out of the nanotubes without being absorbed. The work is described in the journal Applied Physics Letters.

Guo says if an aeroplane painted with the nanotube coating were hit with a radar beam, nothing would bounce back and appear as if nothing were there.

"This type of cloaking is very interesting, especially since they have demonstrated operation in air," says Ray Baughman, director of the MacDiarmid NanoTech Institute at the University of Texas at Dallas. Baughman recently demonstrated that nanotubes can form an invisibility cloak when heated up underwater. The heat from a sheet of nanotubes affects the optical properties of the surrounding water, creating the illusion of invisibility.

Invisibility cloaks shield objects by manipulating incident light to simply flow around them. Materials that can achieve this must be made painstakingly and typically only work with a narrow spectrum of light—say, microwaves, or red or green light. Nanotubes are relatively easy to make and work across a broad spectrum.

However, it's not yet practical to grow forests of nanotubes on the surface of an aeroplane directly—growing such forests is a high-temperature, high-pressure process done in chambers much smaller than an aeroplane. But Guo says it should be possible to grow the nanotubes on the surface of tiny particles which can then be suspended in paint.

The Trouble With India's People Car

Cheap wheels: The no-frills Nano weighs 1,300 pounds and has a two-cylinder engine.
AP Photo/Ajit Solanki

See the rest of our Business Impact report on Disruptive Innovation.

BUSINESS

The Trouble With India's People Car

Tata created the world's least expensive automobile. The only problem now is selling it.

• BY MAHENDRA RAMSINGHANI

Audio »

Ratan Tata, head of the 143-year-old Indian conglomerate that bears his family name, is known as a passionate innovator so committed to risk-taking in his $83 billion empire that he gives an annual award for the "best failed idea." But that prize could go to Tata himself for one of his own dream projects: the Nano car.

The launch of Tata Nano in 2009 was hailed as a milestone in automotive history. At 123,000 rupees, or $2,400, the Nano was dubbed "the world's cheapest car" and called a flagship example of Tata's idea of frugal innovation. It illustrated how engineering could be used to open markets in a country where per capita income is around $1,000 a year.

At first, Tata's "people's car" looked as if it could be India's Model T. Where Ford had used assembly-line innovations to create the first mass-market car, the Nano would push affordability to an extreme. Tata's engineering team introduced a lightweight hollow steering column and tore up plans for the car's floor 10 times. Smaller tires were designed using less rubber and the wheels have three lug nuts instead of four. According to the market research firm Frost and Sullivan, the German auto supplier Bosch stripped out as many as 700 of the 1,000 functions of its electronic fuel injection and engine controls to develop cheaper versions for the Nano. All told, Tata filed around 35 patents on the technology that went in to the car's design.

When the Nano was unveiled, accolades rolled in, including the Frost and Sullivan Innovation Award. Analysts predicted that the vehicle would increase by a staggering 65 percent the number of Indian families able to own a car.

Instead, the Nano has become a hard lesson in marketing to the bottom of the economic pyramid. Just 70,432 of the cars were sold during the fiscal year ending in March. At first, some target customers were intimidated by Tata's glittering showrooms (about half of Nano buyers had never owned a car before). Others apparently just didn't like the idea of purchasing the world's cheapest car. In a country where incomes have doubled in the past five years, the Nano is seen as a glorified version of a tuk-tuk, the three-wheeled motorized rickshaw often seen on the streets of developing nations. Many consumers stretched their budgets to buy the Maruti-Suzuki Alto, which has a bigger 800cc engine.

Tata may have misjudged the market by offering too little with its people's car. "If you start with a very basic product, soon the customer wants more," says David Cole, chairman emeritus of the Center for Automotive Research, a nonprofit automotive-industry research group. "To precisely hit the market when you are pioneering a segment is difficult."

Tata says it is "confident" in the Nano but has been revamping its marketing plans. Ratan Tata himself went out to meet with dealers and executives even struck a deal to display cars at Big Bazaar, a chain of retail discount stores where one can buy plastic buckets and curry powder. So far, sales continue to be choppy and are falling well short of Tata's ambition of selling 20,000 cars per month

One answer could be more technology. Tata has diesel and electric, versions of the Nano on the drawing board, although Cole wonders if such strategies will work. "If the market is soft, you cannot solve market problems by adding technology features," he says. "Hybrid or diesel versions can potentially double the costs of Nano–a very risky step."

Tata continues to push ahead with frugal innovation, including a $700 prefabricated home[ck] and a low-cost water filter called Swach. One idea that didn't make it was an inexpensive all-plastic door designed for the Nano. But it was a good effort. The door was a nominee for the "Dare to Try" award, the one for the best failed idea.

Mahendra Ramsinghani is the author of The Business of Venture Capital (John Wiley, 2011) and manages Invest Detroit's First Step Fund.

Water Theme - S.Jerry Stalin - Jaffna

                                               S.Jerry Stalin - Music Composer & Director From Jaffna Sri lanka. Studied at St.Patrick's College, Jaffna, works with audio Productions & Sound Engineering, with CPArts, Kalaithuthu Studios, and SJ Studio AV Pro. known as "SJ"
upcoming producer from Jaffna - with the Music Lable "Yarl Music". This Water "Short Story" Made for AAA Movies International's Award Programe & won the best music Award 2011 in Jaffna, Sri lanka.