Nobel Prize in Physics 2010 for Graphene -- 'Two-Dimensional' Material

Nobel Prize in Physics 2010 for Graphene -- 'Two-Dimensional' Material

  11:47:00 PM    Science Lover

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The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Physics for 2010 to Andre Geim and Konstantin Novoselov, both of the University of Manchester, "for groundbreaking experiments regarding the two-dimensional material graphene."

Graphene from graphite: Graphite is a basic material found in nature. When taken apart graphite sheets become graphene. A rolled up layer of graphene forms a carbon nanotube, folded up it becomes a small football, fullerene. Hidden inside graphite, graphene was waiting to be discovered. (Credit: © Airi Iliste/The Royal Swedish Academy of Sciences)

A thin flake of ordinary carbon, just one atom thick, lies behind this year's Nobel Prize in Physics. Geim and Novoselov have shown that carbon in such a flat form has exceptional properties that originate from the remarkable world of quantum physics.

Graphene is a form of carbon. As a material it is completely new -- not only the thinnest ever but also the strongest. As a conductor of electricity it performs as well as copper. As a conductor of heat it outperforms all other known materials. It is almost completely transparent, yet so dense that not even helium, the smallest gas atom, can pass through it. Carbon, the basis of all known life on earth, has surprised us once again.

Geim and Novoselov extracted the graphene from a piece of graphite such as is found in ordinary pencils. Using regular adhesive tape they managed to obtain a flake of carbon with a thickness of just one atom. This at a time when many believed it was impossible for such thin crystalline materials to be stable.

However, with graphene, physicists can now study a new class of two-dimensional materials with unique properties. Graphene makes experiments possible that give new twists to the phenomena in quantum physics. Also a vast variety of practical applications now appear possible including the creation of new materials and the manufacture of innovative electronics. Graphene transistors are predicted to be substantially faster than today's silicon transistors and result in more efficient computers.

Since it is practically transparent and a good conductor, graphene is suitable for producing transparent touch screens, light panels, and maybe even solar cells.

When mixed into plastics, graphene can turn them into conductors of electricity while making them more heat resistant and mechanically robust. This resilience can be utilised in new super strong materials, which are also thin, elastic and lightweight. In the future, satellites, airplanes, and cars could be manufactured out of the new composite materials.

This year's Laureates have been working together for a long time now. Konstantin Novoselov, 36, first worked with Andre Geim, 51, as a PhD-student in the Netherlands. He subsequently followed Geim to the United Kingdom. Both of them originally studied and began their careers as physicists in Russia. Now they are both professors at the University of Manchester.

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A New Way to Make Stem Cells Using RNA instead of DNA could avoid the health risks--and the political pitfalls--of stem-cell treatments.

A New Way to Make Stem Cells Using RNA instead of DNA could avoid the health risks--and the political pitfalls--of stem-cell treatments.

  1:27:00 AM    Science Lover

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A Harvard researcher has developed a way to make pluripotent stem cells that solves several of the major impediments to using them to treat human diseases.

New cell: This microscope image shows neurons
(colored green) created from pluripotent stem
cells using modified RNA.
Credit: Phil Manos, Cell Press

Derrick Rossi, an assistant professor at Harvard Medical School, created pluripotent stem cells--which can turn into virtually any other type of cell in the body--from non-stem cells without using viruses to tinker with a cell's genome, as conventional methods do. This means that Rossi's method could be substantially safer for treating disease. The work is published today in the journal Cell Stem Cell.

"Rossi has figured out how to turn a skin cell into a stem cell without genetic modifications, and to do it efficiently," said Doug Melton, codirector of the Harvard Stem Cell Institute, where Rossi is a principal faculty member, at a press conference.

Rossi's innovation, which has not yet been tested in people, was to use messenger RNA instead of DNA to produce the four proteins needed to reprogram the cell. He has started a company called ModeRNA to commercialize this use of messenger RNA. He said the approach may also have potential in gene therapy, which also relies on viruses to deliver treatment, but he declined to talk further about the company or possible gene therapy applications because the work is at such an early stage.

Improving the usability of man-made stem cells is key to helping patients and ending the political morass that has slowed stem-cell research. On Tuesday, a U.S. federal appeals court allowed federal funding of embryonic stem-cell research to continue while a legal case against such funding proceeds.

The human embryonic stem cells used in research were mostly derived from embryonic tissue grown a decade ago. These are the most versatile cells in the body, and the gold standard by which man-made cells are judged.

Four years ago, Japanese researcher Shinya Yamanaka showed that regular cells could be turned into embryonic-like stem cells--called induced pluripotent stem (iPS) cells--through the introduction of four specific proteins. Theoretically, this meant that doctors could take skin cells from a sick or disabled person, transform them into stem cells, and then into a specialized cell to treat them--an insulin-producing islet cell for someone with diabetes or a nerve cell for someone who is paralyzed, for instance. Using iPS cells avoids the need to destroy embryos and, because they can be derived from the patient's own cells, means less risk of rejection.

But only one in 1,000 or one in 10,000 skin cells could be transformed into a stem cell using Yamanaka's method. It also changes a cell's genes in ways that might trigger cancer or other problems.

Rossi 's idea was to produce Yamanaka's four proteins in a different way. Instead of using the DNA that holds the instructions for making proteins, he wanted to use RNA, which carries those instructions to the place in a cell where proteins are made.

His first several attempts were miserable failures. When he tried to change the messages the RNA carried, he triggered a serious immune response and most of the cells shut down or self-destructed. Rossi then tried modifying the RNA chemically and eventually figured out a way to allow his changes to escape immune detection while delivering the message. "This was key to our success," said Rossi, who is also a researcher at Children's Hospital Boston. "We could encode RNA for any protein we wanted to express and insert it into a cell."

Rossi said it was a happy coincidence that using RNA instead of changing the DNA was as much as 100-fold more efficient. He said the effect was possibly because the process more closely reflects how cells themselves transform.

Rossi successfully differentiated his stem cells into muscle cells using RNA, a process that may offer promise in gene therapy and other treatments. His method does not alter the cell's underlying genome, though Rossi admits that he does not yet understand what it does to the cell's epigenome, which controls expression of genes.

Rossi said that his cells, which he's named RiPS, for "RNA induced Pluripotent Stem" cells, are more like embryonic stem cells than traditional iPS cells because they have not been genetically altered.

Melton said the Harvard Stem Cell Institute, which includes several hundred stem-cell researchers from across Harvard University and its affiliated hospitals, will now be making its standard iPS cells with Rossi's method.

In a prepared statement, Yamanaka, now at the University of California, San Francisco, said Rossi's approach to generating stem cells seems promising, and he would like to have someone in his lab try it.

"The quality of the induced pluripotent stem cells generated by this method should be carefully examined because their characteristics vary depending on the induction methods and the origins of the resulting cells," he said. "The standard method to generate iPSCs for clinical applications has yet to be established. I think this method has the potential for it."

Jacob Hanna, a postdoctoral fellow at the Whitehead Institute for Biomedical Research in Cambridge, said he's also eager to begin working with the cells.

"I think it's a very exciting paper with a very promising method," said Hanna, who was not involved in the research. When asked if he was jealous that Rossi had developed the method first, Hanna said, "Yes, of course! It's a very nice paper," quickly adding, "Jealous in a very positive and supporting way."

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Unlocking the Secret of Beauty: Scientists Discover the Complexities of Attractive Female Bodies

Unlocking the Secret of Beauty: Scientists Discover the Complexities of Attractive Female Bodies

  9:49:00 AM    Science Lover

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Scientists in Australia and Hong Kong have conducted a comprehensive study to discover how different body measurements correspond with ratings of female attractiveness. The study, published in the Journal of Evolutionary Biology, found that across cultural divides young, tall and long armed women were considered the most attractive.

Scientists in Australia and Hong Kong have conducted a comprehensive study to discover how different body measurements correspond with ratings of female attractiveness. The study found that across cultural divides young, tall and long armed women were considered the most attractive. (Credit: iStockphoto/Lev Dolgatshjov)

"Physical attractiveness is an important determining factor for evolutionary, social and economic success," said lead author Robert Brooks from the University of New South Wales. "The dimensions of someone's body can tell observers if that person is suitable as a potential mate, a long term partner or perhaps the threat they pose as a sexual competitor."

Traditional studies of attractiveness have been bound to the Darwinian idea of natural selection, which argues that an individual will always choose the best possible mate that circumstances will allow. Such studies have focused on torso, waist, bust and hip measurements.

In this study the team measured the attractiveness of scans of 96 bodies of Chinese women who were either students or volunteers, aged between 20-49 years of age.

Videos of the models were shown to a sample of 92 Australian adults, 40 men and 52 women, aged between 18 to 58 years of age, and mostly of European descent. They then compared the attractiveness ratings given by the Australian group to the ratings from a group in Hong Kong to avoid cultural bias.

Both sample groups were asked to rate the models' attractiveness on a 7 point scale; on average the raters took just 5.35 seconds to rate each model. The team then explored the statistical results, focusing on age, body weight and a range of length and girth measurements.

The results showed that there was a strong level of agreement between the 4 groups of Australian men and women, and Hong Kong men and women, with scans of younger, taller and lighter women being rated as more attractive. Women with narrow waists, especially relative to their height, were also considered much more attractive.

The study also revealed that BMI (Body mass index) and HWR (Hip to waist ratio) were both strong predictors of attractiveness. Scans of taller women who had longer arms were also rated highly, however leg size did not contribute significantly to the ratings.

"Our results showed consistent attractiveness ratings by men and women and by Hong Kong Chinese and Australian raters, suggesting considerable cross cultural consistency," concluded Brooks. "In part this may be due to shared media experiences. Nonetheless when models are stripped of their most obvious racial and cultural features, the features that make bodies attractive tend to be shared by men and women across cultural divides."

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Turning Waste Heat Into Power

Turning Waste Heat Into Power

  2:06:00 AM    Science Lover

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What do a car engine, a power plant, a factory and a solar panel have in common? They all generate heat -- a lot of which is wasted.

A "forest" of molecules holds the promise of turning waste heat into electricity. UA physicists discovered that because of quantum effects, electron waves traveling along the backbone of each molecule interfere with each other, leading to the buildup of a voltage between the hot and cold electrodes (the golden structures on the bottom and top). (Credit: Justin Bergfield, University of Arizona)

University of Arizona physicists have discovered a new way of harvesting waste heat and turning it into electrical power.

Using a theoretical model of a so-called molecular thermoelectric device, the technology holds great promise for making cars, power plants, factories and solar panels more efficient, to name a few possible applications. In addition, more efficient thermoelectric materials would make ozone-depleting chlorofluorocarbons, or CFCs, obsolete.

The research group led by Charles Stafford, associate professor of physics, published its findings in the September issue of the scientific journal, ACS Nano.

"Thermoelectricity makes it possible to cleanly convert heat directly into electrical energy in a device with no moving parts," said lead author Justin Bergfield, a doctoral candidate in the UA College of Optical Sciences.

"Our colleagues in the field tell us they are pretty confident that the devices we have designed on the computer can be built with the characteristics that we see in our simulations."

"We anticipate the thermoelectric voltage using our design to be about 100 times larger than what others have achieved in the lab," Stafford added.

Catching the energy lost through waste heat has been on the wish list of engineers for a long time but, so far, a concept for replacing existing devices that is both more efficient and economically competitive has been lacking.

Unlike existing heat-conversion devices such as refrigerators and steam turbines, the devices of Bergfield and Stafford require no mechanics and no ozone-depleting chemicals. Instead, a rubber-like polymer sandwiched between two metals acting as electrodes can do the trick.

Car or factory exhaust pipes could be coated with the material, less than 1 millionth of an inch thick, to harvest energy otherwise lost as heat and generate electricity.

The physicists take advantage of the laws of quantum physics, a realm not typically tapped into when engineering power-generating technology. To the uninitiated, the laws of quantum physics appear to fly in the face of how things are "supposed" to behave.

The key to the technology lies in a quantum law physicists call wave-particle duality: Tiny objects such as electrons can behave either as a wave or as a particle.

"In a sense, an electron is like a red sports car," Bergfield said. "The sports car is both a car and it's red, just as the electron is both a particle and a wave. The two are properties of the same thing. Electrons are just less obvious to us than sports cars."

Bergfield and Stafford discovered the potential for converting heat into electricity when they studied polyphenyl ethers, molecules that spontaneously aggregate into polymers, long chains of repeating units. The backbone of each polyphenyl ether molecule consists of a chain of benzene rings, which in turn are built from carbon atoms. The chain link structure of each molecule acts as a "molecular wire" through which electrons can travel.

"We had both worked with these molecules before and thought about using them for a thermoelectric device," Bergfield said, "but we hadn't really found anything special about them until Michelle Solis, an undergrad who worked on independent study in the lab, discovered that, low and behold, these things had a special feature."

Using computer simulations, Bergfield then "grew" a forest of molecules sandwiched between two electrodes and exposed the array to a simulated heat source.

"As you increase the number of benzene rings in each molecule, you increase the power generated," Bergfield said.

The secret to the molecules' capability to turn heat into power lies in their structure: Like water reaching a fork in a river, the flow of electrons along the molecule is split in two once it encounters a benzene ring, with one flow of electrons following along each arm of the ring.

Bergfield designed the benzene ring circuit in such a way that in one path the electron is forced to travel a longer distance around the ring than the other. This causes the two electron waves to be out of phase once they reunite upon reaching the far side of the benzene ring. When the waves meet, they cancel each other out in a process known as quantum interference. When a temperature difference is placed across the circuit, this interruption in the flow of electric charge leads to the buildup of an electric potential -- voltage -- between the two electrodes.

Wave interference is a concept exploited by noise-cancelling headphones: Incoming sound waves are met with counter waves generated by the device, wiping out the offending noise.

"We are the first to harness the wave nature of the electron and develop a concept to turn it into usable energy," Stafford said.

Analogous to solid state versus spinning hard drive type computer memory, the UA-designed thermoelectric devices require no moving parts. By design, they are self-contained, easier to manufacture and easier to maintain compared to currently available technology.

"You could just take a pair of metal electrodes and paint them with a single layer of these molecules," Bergfield said. "That would give you a little sandwich that would act as your thermoelectric device. With a solid-state device you don't need cooling agents, you don't need liquid nitrogen shipments, and you don't need to do a lot of maintenance."

"You could say, instead of Freon gas, we use electron gas," Stafford added.

"The effects we see are not unique to the molecules we used in our simulation," Bergfield said. "Any quantum-scale device where you have a cancellation of electric charge will do the trick, as long as there is a temperature difference. The greater the temperature difference, the more power you can generate."

Molecular thermoelectric devices could help solve an issue currently plaguing photovoltaic cells harvesting energy from sunlight.

"Solar panels get very hot and their efficiency goes down," Stafford said. "You could harvest some of that heat and use it to generate additional electricity while simultaneously cooling the panel and making its own photovoltaic process more efficient."

"With a very efficient thermoelectric device based on our design, you could power about 200 100-Watt light bulbs using the waste heat of an automobile," he said. "Put another way, one could increase the car's efficiency by well over 25 percent, which would be ideal for a hybrid since it already uses an electrical motor."

So, next time you watch a red sports car zip by, think of the hidden power of the electron and how much more efficient that sports car could be with a thermoelectric device wrapped around its exhaust pipe.

Funding for this research was provided by the University of Arizona physics department.

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Collective Intelligence: Number of Women in Group Linked to Effectiveness in Solving Difficult Problems

Collective Intelligence: Number of Women in Group Linked to Effectiveness in Solving Difficult Problems

  1:55:00 AM    Science Lover

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When it comes to intelligence, the whole can indeed be greater than the sum of its parts. A new study co-authored by MIT, Carnegie Mellon University, and Union College researchers documents the existence of collective intelligence among groups of people who cooperate well, showing that such intelligence extends beyond the cognitive abilities of the groups' individual members, and that the tendency to cooperate effectively is linked to the number of women in a group.

When it comes to intelligence, the whole can indeed be 
greater than the sum of its parts. A new study documents 
the existence of collective intelligence among groups of 
people who cooperate well, showing that such intelligence 
extends beyond the cognitive abilities of the groups' 
individual members, and that the tendency to cooperate 
effectively is linked to the number of women in a group. 
(Credit: iStockphoto/Jacob Wackerhausen)

Many social scientists have long contended that the ability of individuals to fare well on diverse cognitive tasks demonstrates the existence of a measurable level of intelligence in each person. In a study published Sept. 30, in the advance online issue of the journal Science, the researchers applied a similar principle to small teams of people. They discovered that groups featuring the right kind of internal dynamics perform well on a wide range of assignments, a finding with potential applications for businesses and other organizations.

"We set out to test the hypothesis that groups, like individuals, have a consistent ability to perform across different kinds of tasks," says Anita Williams Woolley, the paper's lead author and an assistant professor at Carnegie Mellon's Tepper School of Business. "Our hypothesis was confirmed," continues Thomas W. Malone, a co-author and Patrick J. McGovern Professor of Management at the MIT Sloan School of Management. "We found that there is a general effectiveness, a group collective intelligence, which predicts a group's performance in many situations."

That collective intelligence, the researchers believe, stems from how well the group works together. For instance, groups whose members had higher levels of "social sensitivity" were more collectively intelligent. "Social sensitivity has to do with how well group members perceive each other's emotions," says Christopher Chabris, a co-author and assistant professor of psychology at Union College in New York. "Also, in groups where one person dominated, the group was less collectively intelligent than in groups where the conversational turns were more evenly distributed," adds Woolley. And teams containing more women demonstrated greater social sensitivity and in turn greater collective intelligence compared to teams containing fewer women.

To arrive at their conclusions, the researchers conducted studies at MIT's Center for Collective Intelligence and Carnegie Mellon, in which 699 people were placed in groups of two to five. The groups worked together on tasks that ranged from visual puzzles to negotiations, brainstorming, games and complex rule-based design assignments. The researchers concluded that a group's collective intelligence accounted for about 40 percent of the variation in performance on this wide range of tasks.

Moreover, the researchers found that the performance of groups was not primarily due to the individual abilities of the group's members. For instance, the average and maximum intelligence of individual group members did not significantly predict the performance of their groups overall.

Only when analyzing the data did the co-authors suspect that the number of women in a group had significant predictive power. "We didn't design this study to focus on the gender effect," Malone says. "That was a surprise to us." However, further analysis revealed that the effect seemed to be explained by the higher social sensitivity exhibited by females, on average. "So having group members with higher social sensitivity is better regardless of whether they are male or female," Woolley explains.

Malone believes the study applies to many kinds of organizations. "Imagine if you could give a one-hour test to a top management team or a product development team that would allow you to predict how flexibly that group of people would respond to a wide range of problems that might arise," he says. "That would be a pretty interesting application. We also think it's possible to improve the intelligence of a group by changing the members of a group, teaching them better ways of interacting or giving them better electronic collaboration tools."

Woolley and Malone say they and their co-authors "definitely intend to continue research on this topic," including studies on the ways groups interact online, and they are "considering further studies on the gender question." Still, they believe their research has already identified a general principle indicating how the whole adds up to something more than the sum of its parts. As Woolley explains, "It really calls into question our whole notion of what intelligence is. What individuals can do all by themselves is becoming less important; what matters more is what they can do with others and by using technology."

"Having a bunch of smart people in a group doesn't necessarily make the group smart," concludes Malone.

In addition to Woolley, Malone and Chabris, the other co-authors were Alexander Pentland, the Toshiba Professor of Media Arts & Science at the MIT Media Lab; and Nada Hashmi, a doctoral candidate at MIT Sloan.

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Genetically Altered Trees Fight Global Warming?

Genetically Altered Trees Fight Global Warming?

  12:35:00 PM    Science Lover

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Forests of genetically altered trees and other plants could sequester several billion tons of carbon from the atmosphere each year and so help ameliorate global warming, according to estimates published in the October issue of BioScience.

New research examines the prospects for enhancing biological carbon sequestration through a variety of policy and technical approaches, including the deployment of genetically engineered trees and other plants. (Credit: iStockphoto)

The study, by researchers at Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory, outlines a variety of strategies for augmenting the processes that plants use to sequester carbon dioxide from the air and convert it into long-lived forms of carbon, first in vegetation and ultimately in soil.

Besides increasing the efficiency of plants' absorption of light, researchers might be able to genetically alter plants so they send more carbon into their roots--where some may be converted into soil carbon and remain out of circulation for centuries. Other possibilities include altering plants so that they can better withstand the stresses of growing on marginal land, and so that they yield improved bioenergy and food crops. Such innovations might, in combination, boost substantially the amount of carbon that vegetation naturally extracts from air, according to the authors' estimates.

The researchers stress that the use of genetically engineered plants for carbon sequestration is only one of many policy initiatives and technical tools that might boost the carbon sequestration already occurring in natural vegetation and crops.

The article, by Christer Jansson, Stan D. Wullschleger, Udaya C. Kalluri, and Gerald A. Tuskan, is the first in a Special Section in the October BioScience that includes several perspectives on the prospects for enhancing biological carbon sequestration. Other articles in the section analyze the substantial ecological and economic constraints that limit such efforts. One article discusses the prospects for sequestering carbon by culturing algae to produce biofuel feedstocks; one proposes a modification of the current regulatory climate for producing genetically engineered trees in the United States; and one discusses societal perceptions of the issues surrounding the use of genetically altered organisms to ameliorate warming attributed to the buildup of greenhouse gases.

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Three Solid-State Qubits Entangled: Big Step Toward Quantum Error Correction

Three Solid-State Qubits Entangled: Big Step Toward Quantum Error Correction

  11:19:00 AM    Science Lover

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The rules that govern the world of the very small, quantum mechanics, are known for being bizarre. One of the strangest tenets is something called quantum entanglement, in which two or more objects (such as particles of light, called photons) become inextricably linked, so that measuring certain properties of one object reveals information about the other(s), even if they are separated by thousands of miles. Einstein found the consequences of entanglement so unpalatable he famously dubbed it "spooky action at a distance."

The quantum entanglement of three solid-state qubits, or quantum bits, represents the first step towards quantum error correction, a crucial aspect of future quantum computing. (Credit: iStockphoto/Yenwen Lu)

Now a team led by Yale researchers has harnessed this counterintuitive aspect of quantum mechanics and achieved the entanglement of three solid-state qubits, or quantum bits, for the first time. Their accomplishment, described in the Sept. 30 issue of the journal Nature, is a first step towards quantum error correction, a crucial aspect of future quantum computing.

"Entanglement between three objects has been demonstrated before with photons and charged particles," said Steven Girvin, the Eugene Higgins Professor of Physics & Applied Physics at Yale and an author of the paper. "But this is the first three-qubit, solid-state device that looks and feels like a conventional microprocessor."

The new result builds on the team's development last year of the world's first rudimentary solid-state quantum processor, which they demonstrated was capable of executing simple algorithms using two qubits.

The team, led by Robert Schoelkopf, the William A. Norton Professor of Applied Physics & Physics at Yale, used artificial "atoms" -- actually made up of a billion aluminum atoms that behave as a single entity -- as their qubits. These "atoms" can occupy two different energy states, akin to the "1" and "0" or "on" and "off" states of regular bits used in conventional computers. The strange laws of quantum mechanics, however, allow for qubits to be placed in a "superposition" of these two states at the same time, resulting in far greater information storage and processing power.

In this new study, the team was able to achieve an entangled state by placing the three qubits in a superposition of two possibilities -- all three were either in the 0 state or the 1 state. They were able to attain this entangled state 88 percent of the time.

With the particular entangled state the team achieved, they also demonstrated for the first time the encoding of quantum information from a single qubit into three qubits using a so-called repetition code. "This is the first step towards quantum error correction, which, as in a classical computer, uses the extra qubits to allow the computer to operate correctly even in the presence of occasional errors," Girvin said.

Such errors might include a cosmic ray hitting one of the qubits and switching it from a 0 to a 1 state, or vice versa. By replicating the qubits, the computer can confirm whether all three are in the same state (as expected) by checking each one against the others.

"Error correction is one of the holy grails in quantum computing today," Schoelkopf said. "It takes at least three qubits to be able to start doing it, so this is an exciting step."

Other authors of the paper include Leonardo DiCarlo, Matthew Reed, Luyan Sun, Blake Johnson, Jerry Chow and Michel Devoret (all of Yale University); and Jay Gambetta (University of Waterloo).

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IBEX Finds Surprising Changes at Solar Boundary

IBEX Finds Surprising Changes at Solar Boundary

  10:53:00 PM    Science Lover

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When NASA launched the Interstellar Boundary Explorer (IBEX) on October 19, 2008, space physicists held their collective breath for never-before-seen views of a collision zone far beyond the planets, roughly 10 billion miles away. That's where the solar wind, an outward rush of charged particles and magnetic fields continuously spewed by the Sun, runs into the flow of particles and fields that permeates interstellar space in our neighborhood of the Milky Way galaxy.

Roughly the size of a card table, the Interstellar Boundary 
Explorer is the latest in NASA's series of low-cost, rapidly 
developed Small Explorers spacecraft. (Credit: NASA/
Goddard Space Flight Center Conceptual Image Lab)

No spacecraft had ever imaged the collision zone, which occurs in a region known as the heliosheath, because it emits no light. But the two detectors on IBEX are designed to "see" what the human eye cannot. The interaction of the solar wind and interstellar medium creates energetic neutral atoms of hydrogen, called ENAs, that zip away from the heliosheath in all directions. Some of these atoms pass near Earth, where IBEX records their arrival direction and energy. As the spacecraft slowly spins, the detectors gradually build up pictures of the ENAs as they arrive from all over the sky.

Mission scientists got their first surprise six months after launch, once the spacecraft had scanned enough overlapping strips of sky to create a complete 360° map. Instead of recording a relatively even distribution all the way around, as expected, IBEX found that the counts of ENAs -- and thus the strength of the interaction in the heliosheath -- varied dramatically from place to place. The detectors even discovered a long, enhanced "ribbon," accentuated by an especially intense hotspot or "knot," arcing across the sky. (IBEX Explores Galactic Frontier, Releases First-Ever All-Sky Map)

Now scientists have finished assembling a second complete sweep around the sky, and IBEX has again delivered an unexpected result: the map has changed significantly. Overall, the intensity of ENAs has dropped 10% to 15%, and the hotspot has diminished and spread out along the ribbon. Details of these findings appear in the September 27th issue of Journal of Geophysical Research (Space Physics).

"We thought we might detect small changes occurring gradually throughout the Sun's 11-year-long activity cycle, but not over just 6 months," notes David McComas (Southwest Research Institute), principal investigator for the IBEX mission and the paper's lead author. "These observations show that the interaction of the Sun with the interstellar medium is far more dynamic and variable than anyone envisioned."

In the past, space physicists had little notion of what to expect along the boundary where the Sun's own magnetic bubble, the heliosphere, meets interstellar space. Even though the solar wind travels outward at roughly a million miles per hour, it still takes about a year to reach the heliosphere's edge. Also, the encounter zone within the heliosheath is believed to be several billion miles thick (roughly Pluto's distance from the Sun). Finally, the ENAs take another six months to many years to complete the return trip back to Earth, depending on their direction and energy.

With ENAs starting out from such a wide range of distances and traveling back toward Earth at different speeds, IBEX mission scientists had expected that any highs and lows in intensity arising within the heliosheath would be hopelessly smeared out in the spacecraft's all-sky maps. So they're elated by the variations and changes seen so far by IBEX. These early results hint that the solar wind and the interstellar flow might be interacting in a thinner layer than many researchers had imagined possible.

McComas says the dropoff in intensity between the two all-sky maps perhaps makes sense, because the Sun is only now emerging from an unusually long period of very low activity and a correspondingly weak solar wind. The fewer the solar-wind particles that reached the heliosheath in recent years, the fewer the ENAs that got created. "We didn't plan it this way," says McComas, "but it's an almost perfect situation, in that we're seeing the interaction in its simplest state -- before trying to interpret what turns out to be a much more complicated interaction than anticipated."

If IBEX remains healthy, and if the team gets approval to continue well past its planned two-year mission, then the changes it's seeing in the distant heliosheath should become more dramatic as solar activity ramps up later in this decade.

"The surprising results from IBEX show that there is still exciting science that can be done with small missions," comments Eric Christian, a member of the spacecraft's research team and the program's Deputy Mission Scientist at the Goddard Space Flight Center. "This is clearly a huge success for the Explorer program." IBEX is one of a dozen Explorer-class missions operated by NASA's Science Mission Directorate.

"The public might think that scientists make measurements and instantly know what's going on, but that is not how science really works," McComas observes. "We thought the outer heliosphere would be stable over time -- and IBEX is showing us that it's not. This is changing the game completely."

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ADHD Is a Genetic Disorder Children With ADHD More Likely to Have Missing or Duplicated Segments of DNA

ADHD Is a Genetic Disorder Children With ADHD More Likely to Have Missing or Duplicated Segments of DNA

  10:23:00 AM    Science Lover

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New research provides the first direct evidence that attention-deficit/hyperactivity disorder (ADHD) is a genetic condition. Scientists at Cardiff University found that children with ADHD were more likely to have small segments of their DNA duplicated or missing than other children.

In a new study, children with ADHD were more likely to have small segments of their DNA duplicated or missing than other children. (Credit: iStockphoto/Zmeel Photography)

The study also found significant overlap between these segments, known as copy number variants (CNVs), and genetic variants implicated in autism and schizophrenia, proving strong evidence that ADHD is a neurodevelopmental disorder -- in other words, that the brains of children with the disorder differ from those of other children.

The research, published in the journal The Lancet, was largely funded by the Wellcome Trust, with additional support from Action Medical Research, the Medical Research Council and the European Union.

"We hope that these findings will help overcome the stigma associated with ADHD," says Professor Anita Thapar. "Too often, people dismiss ADHD as being down to bad parenting or poor diet. As a clinician, it was clear to me that this was unlikely to be the case. Now we can say with confidence that ADHD is a genetic disease and that the brains of children with this condition develop differently to those of other children."

ADHD is one of the most common mental health disorders in childhood, affecting around one in 50 children in the UK. Children with ADHD are excessively restless, impulsive and distractible, and experience difficulties at home and in school. Although no cure exists for the condition, symptoms can be reduced by a combination of medication and behavioural therapy.

The condition is highly heritable -- children with ADHD are statistically more likely to also have a parent with the condition and a child with an identical twin with ADHD has a three in four chance of also having the condition. Even so, until now there has been no direct evidence that the condition is genetic and there has been much controversy surrounding its causes, which some people have put down to poor parenting skills or a sugar-rich diet.

The team at Cardiff University analysed the genomes of 366 children, all of whom had been given a clinical diagnosis of ADHD, against over 1,000 control samples in search of variations in their genetic make-up that were more common in children with the condition.

"Children with ADHD have a significantly higher rate of missing or duplicated DNA segments compared to other children and we have seen a clear genetic link between these segments and other brain disorders," explains Dr Nigel Williams. "These findings give us tantalising clues to the changes that can lead to ADHD."

The researchers found that rare CNVs were almost twice as common in children with ADHD compared to the control sample -- and even higher for children with learning difficulties. CNVs are particularly common in disorders of the brain.

There was also significant overlap between CNVs identified in children with ADHD and regions of the genome which are known to influence susceptibility to autism and schizophrenia. Whilst these disorders are currently thought to be entirely separate, there is some overlap between ADHD and autism in terms of symptoms and learning difficulties. This new research suggests there may be a shared biological basis to the two conditions.

The most significant overlap was found at a particular region on chromosome 16 which has been previously implicated in schizophrenia and other major psychiatric disorders and spans a number of genes including one known to play a role in the development of the brain .

"ADHD is not caused by a single genetic change, but is likely caused by a number of genetic changes, including CNVs, interacting with a child's environment," explains Dr Kate Langley. "Screening children for the CNVs that we have identified will not help diagnose their condition. We already have very rigorous clinical assessments to do just that."

Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, which has supported Professor Thapar's work for ten years, says: "These findings are testament to the perseverance of Professor Thapar and colleagues to prove the often unfashionable theory that ADHD is a brain disorder with genetic links. Using leading-edge technology, they have begun to shed light on the causes of what is a complex and often distressing disorder for both the children and their families."

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Nerves, Muscle Regenerated With Sodium Ions

Nerves, Muscle Regenerated With Sodium Ions

  12:35:00 AM    Science Lover

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Sodium gets a bad rap for contributing to hypertension and cardiovascular disease. Now biologists at Tufts University's School of Arts and Sciences have discovered that sodium also plays a key role in initiating a regenerative response after severe injury. The Tufts scientists have found a way to regenerate injured spinal cord and muscle by using small molecule drugs to trigger an influx of sodium ions into injured cells.

Tufts biologists have regenerated spinal cord and 
muscle by using a "pharmaceutical cocktail" to 
trigger an influx of sodium ions into injured cells. The 
treatment method is most directly applicable to spinal
cord repair and limb loss, which are significant problems
worldwide, but the proof-of-principle may apply to many 
complex organs and tissues. The Tufts team found that a 
localized increase in sodium ions was necessary for young 
tadpoles to regenerate their tails -- complex appendages
containing spinal cord, muscle and other tissue. Like 
human beings, who regenerate fingertips only as children, 
tadpoles lose the ability to regenerate their tail with 
age. The Tufts biologists showed that such "refractory" 
tadpoles whose tails had been removed could be induced 
to make a perfect new tail by only an hour of treatment. 
The tadpole on the left, which received the "cocktail" to 
trigger an influx of sodium ions, grew a perfectly formed tail. 
The control tadpole on the right did not regenerate. This 
approach breaks new ground in biomedicine because it 
requires no gene therapy; can be effectively administered
for some time after an injury has occurred; and is bioelectric, 
rather than chemically based. (Credit: Ai-Sun Tseng and 
Michael Levin-Tufts University)

The approach breaks new ground in the field of biomedicine because it requires no gene therapy; can be administered after an injury has occurred and even after the wound has healed over; and is bioelectric, rather than chemically based.

In a paper appearing as the cover story of the September 29, 2010, issue of the Journal of Neuroscience, the Tufts team reported that a localized increase in sodium ions was necessary for young Xenopus laevis tadpoles to regenerate their tails - complex appendages containing spinal cord, muscle and other tissue.

Like human beings, who regenerate fingertips only as children, these tadpoles lose the ability to regenerate their tail with age. Most remarkably, it was shown that such "refractory" tadpoles whose tails had been removed could be induced to make a perfect new tail by only an hour of treatment with a specific drug cocktail.

The findings have tremendous implications for treating wounds sustained in war as well as accidental injuries. The treatment method used is most directly applicable to spinal cord repair and limb loss, which are highly significant medical problems world-wide. It also demonstrates a proof-of-principle that may be applicable to many complex organs and tissues.

"We have significantly extended the effective treatment window, demonstrating that even after scar-like wound covering begins to form, control of physiological signals can still induce regeneration. Artificially causing an influx of sodium for just one hour can overcome a variety of problems, such as the decline in regenerative ability that comes with age and the effect of regeneration-blocking drugs," said Tufts Professor of Biology Michael Levin, Ph.D., corresponding author on the paper and director of the Center for Regenerative and Developmental Biology at Tufts. Co-authors were Research Associate Ai-Sun Tseng, Postdoctoral Associate Wendy S. Beane, Research Associate Joan M. Lemire, and Alessio Masi, a former post-doctoral associate in Levin's laboratory.

The transport of ions in and out of cells is regulated by electronic security doors, or gates, that let in specific ions under certain circumstances. A role for sodium current in tissue regeneration had been proposed in the past, but this is the first time the molecular-genetic basis of the ion flow has been identified, and a specific drug-based treatment demonstrated. Until now, advances in this model system had involved administering therapies before the injury was sustained.

"This is a novel, biomedically-relevant approach to inducing regeneration of a complex appendage," noted Levin.

The Tufts research established a novel role in regeneration for the sodium channel Nav1.2, a crucial component of nerve and cardiac function. It showed that local, early increase in intracellular sodium is required for initiating regeneration following Xenopus tail amputation, while molecular and pharmacological inhibition of sodium transport causes regenerative failure. The new treatment induced regeneration only of correctly-sized and patterned tail structures and did not generate ectopic or other abnormal growth.

"The ability to restore regeneration using a temporally-controllable pharmacological approach not requiring gene therapy is extremely exciting," said the researchers.

Of critical importance, they said, was the discovery that the tail could be induced to regenerate as late as 18 hours after amputation, revealing that tissues normally fated for regenerative failure still maintain their intrinsic characteristics and can be programmed to reactivate regeneration.

Amphibians such as frogs can restore organs lost during development, including the lens and tail. The frog tail is a good model for human regeneration because it repairs injury in the same way that people do: each tissue makes more of itself. (In contrast, regeneration in some other animals occurs through transdifferentiation (one cell type turns into another cell type) or adult stem cell differentiation. Furthermore, though small, the Xenopus larval tail is complex, with muscle, spinal cord, peripheral nerves and vasculature cells.

The National Institutes of Health, National Highway Traffic Safety Administration, Department of Defense and Defense Advanced Research Projects Agency funded the work.

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