Friday, September 29, 2006

Tarantulas Produce Silk From Their Feet

Researchers have found for the first time that tarantulas can produce silk from their feet as well as their spinnerets, a discovery with profound implications for why spiders began to spin silk in the first place.

Adam Summers, a UC Irvine assistant professor of ecology and evolutionary biology, was among the team of scientists who made the discovery using zebra tarantulas from Costa Rica. The team found that the tarantulas secrete silk from spigots on their legs, allowing them to better cling to surfaces. Until now, spiders were only known to spin silk from spinnerets located on their abdomen and to use the silk to form webs for protection and capturing prey rather than for locomotion.

“If we find that other spiders in addition to these tarantulas have the ability to secrete silk from their feet, this could represent a major change in our evolutionary hypothesis regarding spider silk,” Summers said. “It could mean that silk production actually originated in the feet to increase traction, with the diversity of spinneret silk evolving later.”

The researchers placed tarantulas on a vertical glass surface. Though ground dwelling, these spiders can normally hang on to vertical surfaces by using thousands of spatulate hairs and small claws. However, the scientists noticed that when the spider started to slip down the surface, it produced silk from all four pairs of legs, allowing it to adhere to the glass for more than 20 minutes. The silk secretions were clearly visible on the glass. Using scanning electron microscopy, the scientists also were able to see the openings on the legs that resemble the silk-producing spigots on spider abdominal spinnerets.

The next step, according to Summers, is to investigate whether the silk produced by the feet is the same as that produced by the spinneret. Many spiders can produce seven different kinds of silk. Scientists will look at the genes involved in silk production from the feet, compare them to the gene family that leads to spinneret silk production, and be able to better determine whether silk was originally used for traction, or whether that was a secondary usage that came later.

Thursday, September 28, 2006

Bose-Einstein Condensation In The Solid State

New experimental research shows that half-matter, half-light quasi-particles called polaritons show compelling evidence of Bose-Einstein condensation at the relatively high temperature of 19 degrees Kelvin. The creation of a polariton Bose-Einstein condensate in the solid state provides scientists with a unique opportunity to better understand and possibly exploit the quantum effects that occur in these very special conditions.

Researchers at EPFL (Ecole Polytechnique Federale de Lausanne), collaborating with colleagues at University of Grenoble, Cambridge, Oxford and MIT, have reported the observation of polaritons displaying the defining features of Bose Einstein condensation -a macroscopically ordered state, long-range spatial coherence and polarization - for the first time in solid state. Their results appear in an article in the September 28 issue of the journal Nature.

Bose-Einstein condensates are sometimes referred to as a "fifth state of matter", a special phase in which all the particles share the same quantum state. This phase was predicted by Satyendranath Bose and Albert Einstein in 1924. Getting atoms cold enough to provide experimental proof of its existence took seventy more years, and the first successful experiments using Rubidium atoms won Eric Cornell, Wolfgang Ketterle and Carl Wieman the 2001 Nobel prize in physics. Cooled to within a hair of absolute zero, the atoms in dilute clouds of bosonic gases stop moving and condense, not into a liquid, but into a new phase called a condensate, in which the atoms all share the same quantum state. Like photons in a laser, the particles are coherent, behaving en masse like a "super-particle."

The possibility of a phase change into a Bose-Einstein-like condensate theoretically applies for all bosonic particles, including electron-hole pairs called excitons and half exciton, half photon quasi-particles called polaritons. Exploring Bose-Einstein condensation and its intriguing quantum effects using these quasi-particles is particularly interesting because their light mass makes things much easier. A polariton is a billion times lighter than a Rubidium atom, and 10,000 times lighter than an electron. This means that polaritons can transform into a Bose-Einstein condensate at a much higher temperature than alkali gases. Some of the possibilities that have been suggested for applications of the quantum effects of the Bose-Einstein phase - quantum computing, quantum clocks or atomic or lasers that use matter instead of light - are only realistically conceivable if these condensates can be achieved at room temperature, or at least temperatures that can be reached using standard cryogenic techniques.

Signatures of exciton and polariton coherence have been previously observed in semiconductor microcavities, but conclusive proof, such as evidence of polarization and long range particle coherence, has remained elusive because the particles only live a trillionth of a second.

The experiments of the EPFL-led team provide the first convincing evidence of a Bose-Einstein like condensate in the solid state. The researchers confined photons in a semiconductor microcavity containing a large number of quantum wells, and then used a laser to excite the semiconductor, generating polaritons. At a critical density, at the easily attainable temperature of 19 degrees Kelvin (about -254 Celsius), the polaritons showed evidence of spontaneous coalescence into a single coherent ground state. The classic phase transition characteristics - macroscopic polarization and spatial coherence across the entire condensate - are clearly seen here, and for the first time in solid state.

According to Professor Benoit Deveaud, leader of the research team, condensates at even higher temperatures could perhaps be achieved using other semiconductor materials.

"The magical properties of superfluidity, where matter flows with zero friction, and superconductivity, where a current flows with zero resistance, are quantum effects, and in the Bose-Einstein condensate they are directly brought to our perception," notes Deveaud. "It is exciting to envision exploring this magic without having to use an incredibly complex machine to get to temperatures just above absolute zero."

What practical applications will this lead to? "We are still exploring the basic physics of this phenomenon," says Deveaud. "But just achieving this phase in the solid state is exciting. In the mid 1900s, transistors replaced vacuum lamps, and now most useful devices are made in the solid state," he explains. "Polaritons, although made with a photon, are really quasi-particles in the solid. It is likely that they can be manipulated much as electrons are - an advance that has led to incredible new technologies such as the CCD chips in digital cameras."

Tuesday, September 26, 2006

Roll-up Laptop Screens?

Scientists at the University of Cambridge have developed a range of unique, shape-changing structures, which can be used as roll-up display screens (such as laptop screens), re-usable packaging, roll-up keyboards and self-erecting, temporary habitats.

These structures, also known as 'morphing' structures, afford multiple configurations without the need of complex parts or sophisticated manufacturing. Dr Keith Seffen, from the Department of Engineering, has developed the structures and is currently exploring various applications for their ingenious behaviour with co-worker Dr Simon Guest and graduate student Alex Norman.

Dr Seffen said, "They offer substantial shape-changing capabilities whilst preserving structural integrity. They are simply made and their operation does not rely upon advanced materials. They afford compact, inexpensive solutions for multifunctional devices, which are required to be lightweight, stiff, but foldable on demand."

By using an ordinary sheet of metal, Dr Seffen can produce structures with no moving parts but which can be configured between at least two distinct, self-locking and stable forms. For example, an A5-sized flat screen can be snapped into the shape of a tube for compact carriage in a briefcase or pocket.

The operation does not require hinges, latches or locks, and without these extra parts, production times and costs are reduced compared to traditional folding structures.

Sunday, September 24, 2006

New Device Tests Uncertainty Principle With New Precision

In the submicroscopic world - the domain of elementary particles and individual atoms - things behave in the strange, counter-intuitive fashion governed by the principles of quantum mechanics. Nothing (or so it seems) like our macroscopic world - or even the microscopic world of cells or bacteria or dust particles - where Newton's much more reasonable laws keep things sensibly ordered.

The problem comes in finding the dividing line between the two worlds - or even in establishing that such a line exists. To that end, Keith Schwab, associate professor of physics who moved to Cornell this year from the National Security Agency, and colleagues have created a device that approaches this quantum mechanical limit at the largest length-scale to date.

And surprisingly, the research also has shown how researchers can lower the temperature of an object - just by watching it.

The results, which could have applications in quantum computing, cooling engineering and more, appear in the Sept. 14 issue of the journal Nature.

The device is actually a tiny (8.7 microns, or millionths of a meter, long; 200 nanometers, or billionths of a meter, wide) sliver of aluminum on silicon nitride, pinned down at both ends and allowed to vibrate in the middle. Nearby, Schwab positioned a superconducting single electron transistor (SSET) to detect minuscule changes in the sliver's position.

According to the Heisenberg uncertainty principle, the precision of simultaneous measurements of position and velocity of a particle is limited by a quantifiable amount. Schwab and his colleagues were able to get closer than ever to that theoretical limit with their measurements, demonstrating as well a phenomenon called back-action, by which the act of observing something actually gives it a nudge of momentum.

"We made measurements of position that are so intense - so strongly coupled - that by looking at it we can make it move," said Schwab. "Quantum mechanics requires that you cannot make a measurement of something and not perturb it. We're doing measurements that are very close to the uncertainty principle; and we can couple so strongly that by measuring the position we can see the thing move."

The device, while undeniably small, is - at about ten thousand billion atoms - vastly bigger than the typical quantum world of elementary particles.

Still, while that result was unprecedented, it had been predicted by theory. But the second observation was a surprise: By applying certain voltages to the transistor, the researchers saw the system's temperature decrease.

"By looking at it you cannot only make it move; you can pull energy out of it," said Schwab. "And the numbers suggest, if we were to keep going on with this work, we would be able to cool this thing very cold. Much colder than we could if we just had this big refrigerator."

The mechanism behind the cooling is analogous to a process called optical or Doppler cooling, which allows atomic physicists to cool atomic vapor with a red laser. This is the first time the phenomenon has been observed in a condensed matter context.

Schwab hasn't decided if he'll pursue the cooling project. More interesting, he says, is the task of figuring out the bigger problem of quantum mechanics: whether it holds true in the macroscopic world; and if not, where the system breaks down.

For that he's focusing on another principle of quantum mechanics - the superposition principle - which holds that a particle can simultaneously be in two places.

"We're trying to make a mechanical device be in two places at one time. What's really neat is it looks like we should be able to do it," he said. "The hope, the dream, the fantasy is that we get that superposition and start making bigger devices and find the breakdown."

Saturday, September 23, 2006

Cydonia - The Face On Mars

The European Space Agency's Mars Express has obtained images of the Cydonia region, site of the famous 'Face on Mars.' The High Resolution Stereo Camera photos include some of the most spectacular views of the Red Planet ever.

After multiple attempts to image the Cydonia region from April 2004 until July 2006 were frustrated by altitude and atmospheric dust and haze, the High Resolution Stereo Camera (HRSC) on board Mars Express finally obtained, on 22 July, a series of images that show the famous 'face' on Mars in unprecedented detail.

The data were gathered during orbit 3253 over the Cydonia region, with a ground resolution of approximately 13.7 metres per pixel. Cydonia lies at approximately 40.75° North and 350.54° East.

"These images of the Cydonia region on Mars are truly spectacular," said Dr Agustin Chicarro, ESA Mars Express Project Scientist. "They not only provide a completely fresh and detailed view of an area famous to fans of space myths worldwide, but also provide an impressive close-up over an area of great interest for planetary geologists, and show once more the high capability of the Mars Express camera."

Cydonia is located in the Arabia Terra region on Mars and belongs to the transition zone between the southern highlands and the northern plains of Mars. This transition is characterized by wide, debris-filled valleys and isolated remnant mounds of various shapes and sizes.

'Human face' first seen in 1976

One of these visible remnant massifs became famous as the 'Face on Mars' in an image taken on 25 July 1976 by the American Viking 1 Orbiter.

A few days later, on 31 July 1976, a NASA press release said the formation "resembles a human head." However, NASA scientists had already correctly interpreted the image as an optical illusion caused by the illumination angle of the Sun, the formation's surface morphology and the resulting shadows, giving the impression of eyes, nose and mouth.

Nonetheless, the 'Face on Mars' was the subject of widespread speculation on the possible origins and purpose of artificial structures on the Red Planet, with the face being the most talked-about formation.

The array of nearby structures has been interpreted by some space enthusiasts as artificial landscapes, such as potential pyramids and even a disintegrated city. The idea that the planet might have once been home to intelligent beings has since inspired the imagination of many Mars fans, and has been expressed in numerous, more-or-less serious, newspaper articles as well as in science-fiction literature and on many Web pages.

Despite all this, the formal scientific interpretation has never changed: the face remains a figment of human imagination in a heavily eroded surface.

It took until April 1998, and confirmation with additional data from the Mars Orbiter Camera on NASA's Mars Global Surveyor, before popular speculation waned. More data from the same orbiter in 2001 further confirmed this conclusion.

Significance for planetary geologists

While the formations aren't of alien origin, they are nevertheless of significant interest to planetary geologists.In areas adjacent to Cydonia, gently sloping areas surrounding hills or reliefs, so-called 'debris aprons,' are frequently found. They form at the foot of such remnant mounds and probably consist of a mixture of rocky debris and ice. In Cydonia itself, such aprons are often missing in smaller massifs. The formation of debris aprons is considered to be controlled by talus formation, a sloping mass of rock debris at the base of a cliff, and landslides.

At the Mars 'face,' such characteristic landslides and an early form of debris apron formation can be seen.

'Skull-shaped' structure appears in some images

On 22 July, the HRSC finally met success during orbit 3253, and a wide area in Cydonia was imaged at the best possible resolution and in 3D.

In fact, in addition to the well-known 'face' and 'pyramids,' a naturally skull-shaped structure also appears in some of the Mars Express images.

As the famous scientist and writer Carl Sagan said: "Imagination will often carry us to worlds that never were. But without it we go nowhere."

Thursday, September 21, 2006

Hubble Finds Hundreds Of Young Galaxies In Early Universe

Astronomers analyzing two of the deepest views of the cosmos made with NASA's Hubble Space Telescope have uncovered a gold mine of galaxies, more than 500 that existed less than a billion years after the Big Bang. These galaxies thrived when the cosmos was less than 7 percent of its present age of 13.7 billion years. This sample represents the most comprehensive compilation of galaxies in the early universe, researchers said.

The discovery is scientifically invaluable for understanding the origin of galaxies, considering that just a decade ago early galaxy formation was largely uncharted territory. Astronomers had not seen even one galaxy that existed when the universe was a billion years old, so finding 500 in a Hubble survey is a significant leap forward for cosmologists.

The galaxies unveiled by Hubble are smaller than today's giant galaxies and very bluish in color, indicating they are ablaze with star birth. The images appear red because of the galaxies' tremendous distance from Earth. The blue light from their young stars took nearly 13 billion years to arrive at Earth. During the journey, the blue light was shifted to red light due to the expansion of space.

"Finding so many of these dwarf galaxies, but so few bright ones, is evidence for galaxies building up from small pieces - merging together as predicted by the hierarchical theory of galaxy formation," said astronomer Rychard Bouwens of the University of California, Santa Cruz, who led the Hubble study.

Bouwens and his team spied these galaxies in an analysis of the Hubble Ultra Deep Field (HUDF), completed in 2004, and the Great Observatories Origins Deep Survey (GOODS), made in 2003. The results were presented on August 17 at the 2006 General Assembly of the International Astronomical Union, and will be published in the November 20 issue of the Astrophysical Journal.

The findings also show that these dwarf galaxies were producing stars at a furious rate, about ten times faster than is happening now in nearby galaxies. Astronomers have long debated whether the hottest stars in early star-forming galaxies, such as those in this study, may have provided enough radiation to reheat the cold hydrogen gas that existed between galaxies in the early universe. The gas had been cooling since the Big Bang.

"Seeing all of these starburst galaxies provides evidence that there were enough galaxies 1 billion years after the Big Bang to finish reheating the universe," explained team member Garth Illingworth of the University of California, Santa Cruz. "It highlights a period of fundamental change in the universe, and we are seeing the galaxy population that brought about that change."

In terms of human lifetimes, cosmic events happen very slowly. The evolution of galaxies and stars, for example, occurs over billions of years. Astronomers, therefore, rarely witness dramatic, relatively brief transitions that changed the universe. One such event was the universe's "reheating." The reheating, driven by the galaxies' ultraviolet starlight, transformed the gas between galaxies from a cold, dark hydrogen soup to a hot, transparent plasma over only a few hundred million years. With Hubble's help, astronomers are now beginning to see the kinds of galaxies that brought about the reheating.

Tuesday, September 19, 2006

Scientists Get Best Look Ever At Water-life Connection

No one has ever seen exactly how water molecules interact with proteins – even though water is the essential element for life . . . that is, not until now.

Researchers led by Ohio State University physicist Dongping Zhong revealed these interactions for the first time, and report the results in the current issue of the Proceedings of the National Academy of Sciences.

Proteins are complex molecules that form the main support structure for plant and animal cells, and they also regulate biochemical reactions.

Zhong's project aims eventually to explain how water helps enable life-supporting biological functions such as protein folding or enzyme catalysis. But for now, this early result ends decades of controversy on what happens in the microscopic realm where water and proteins meet.

The controversy, Zhong explained, stemmed from the fact that researchers across different disciplines used different methods to study the problem. Because of that, they got different answers on the speed with which these essential biochemical reactions take place. "A biologist will tell you that water and proteins must interact on a nanosecond [one billionth of a second] time scale, because that's how fast proteins move," he said. "And a physicist will tell you that the interaction would happen much faster - on the picosecond [one trillionth of a second] time scale - because that's how fast water molecules move. And someone who uses X-rays will give you a different answer than someone who uses nuclear magnetic resonance and so on."

"My feeling is that there is no real controversy - everybody is just looking at the same answer from different angles," he added.

The answer, revealed in Zhong's lab: water molecules do move fast on their own, but they slow down - to a speed midway between the nanosecond and picosecond scale - to connect with proteins.

Zhong, an assistant professor of physics, used ultra-fast laser pulses to take snapshots of water molecules moving around a protein taken from a common bacterium, Staphylococcus.

The key to getting a good view of the interaction was to precisely locate an optical probe on the protein surface. They inserted a molecule of the amino acid tryptophan into the protein as a probe, and measured how water moved around it - a technique Zhong began to develop when he was a postdoctoral researcher in Nobel laureate Ahmed Zewail's lab at the California Institute of Technology 5 years ago.

Laser studies of the protein while it was immersed in water revealed that far away from the protein - in a region Zhong called "bulk water" - the water molecules were flowing around each other at their typically fast speeds, with each movement requiring only a single picosecond.

But the water near the protein formed several distinct layers. The outermost layer flowed at a slower speed than in bulk water, and the innermost layer even slower. In that innermost layer, each movement of a water molecule to connect with the protein required at least 100 picoseconds to complete.

So when it comes to supporting life - on the molecular scale, anyway - water has to move 100 times slower to get the job done. "The fast-moving water has to slow down to connect with a slow-moving protein - it's that simple," Zhong said. "It sounds trivial, I know. But it should be trivial.”

"It's an essential biological interaction that has to work just right every time. If the water moved too slowly, it could get in the way of proteins trying to meet - it would be a bottleneck in the process. And if it moved too fast, it couldn't connect with the protein at all. So I think this is nature's way of getting the interaction just right."

Monday, September 18, 2006

Earliest Baby Girl Ever Discovered

Some 3.3 million years ago, a three-year-old girl died in present day Ethiopia, in an area called Dikika. Though a baby, she provides researchers with a unique account of our past, as would a grandmother. Her completeness, antiquity, and age at death combined make this find unprecedented in the history of paleoanthropology and open many new research avenues to investigate into the infancy of early human ancestors.

The extraordinary discovery reported this week in the scientific journal Nature, was found in north-eastern Ethiopia, by a paleoanthropological research team led by Dr. Zeresenay Alemseged of the Max Planck Institute in Leipzig, Germany. The scientific significance of the new find is multi-fold, contributing substantially to our comprehension of the morphology, body plan, behaviour, movement and developmental patterns of our early ancestors. After full cleaning and preparation of the fossil it will be possible to reconstruct, for the first time, much of an entire body of a 3 year-old Australopithecus afarensis child, which will resolve many pending questions regarding early human evolution.

The new find consists of a skeleton of the earliest and most complete juvenile human ancestor ever found that lived 150,000 years before Lucy. Dubbed "Lucy's Baby" by some already, she was only three years old when she died and belongs to Australopithecus afarensis (the Lucy species).

The first piece of the baby was found on December 10th, 2000, but recovering the partial skeleton required intensive searching and sifting over four successive field seasons between 2000 and 2004.

To date only recent Hominoids such as Neandertals and modern humans are known from fairly complete skeletons of infants. For the preceding several million years of human evolution, however, not a single young child is know by remains representing more than a skull, a piece of jaw or some isolated teeth. Against this background, the completeness and state of preservation of the Dikika girl stands as one of the major discoveries in the history of paleoanthropology.

The find comprises the whole skull with a natural brain sandstone impression in addition to previously completely unknown or very little known skeletal parts including the hyoid bone. Of the upper part of the skeleton, most of the spinal column, both shoulder blades, the ribs and both collar bones were recovered. Shoulder blades are almost absent in the fossil record of the earliest human ancestors except for fragmentary pieces from Lucy and another Australopithecus species (Australopithecus afarensis). Parts of the lower limb, including both knee caps and substantial parts of the thigh and shin bone from both legs were also recovered in addition to an almost complete foot.

Contextual evidence from the sediments that yielded the baby, in addition to the absence of evidence for carnivore activities, abrasion or corpse transport indicate that she was probably buried in a rapid flood event soon after death. It is also possible that the same flood could have caused her demise.

When discovered, all bones of the upper part of the skeleton including the skull, the shoulder blades, the collar bones, the ribs and the spinal column were encased in a very compact sandstone block and glued to each other. In most cases the difficulty paleoanthropologists face is putting very fragmentary pieces they find back together. In the case of the Dikika girl, however, the challenge was the opposite; sediments had to be removed almost grain by grain using dental instruments passing between ribs and the twisted spinal column. The process has taken the MPI researchers five years so far.

The specimen was also CT scanned at the Diagnostic Centre in Nairobi, Kenya. This technique enabled researchers to examine the developing permanent teeth allowing determination of the sex and age at death of the new fossil.

Among the major scientific contributions of this find are, first, the Dikika girl documents for the first time the complete skull morphology of juvenile Australopithecus afarensis. Based on the new find it is now possible to study how the skull of A. afarensis changed during growth when individuals passed from the childhood to adulthood.

Second, the brain size of the Dikika girl, who was 3 when she died, is estimated at 330 cubic centimetres which is not very different from that of a 3 year-old chimpanzee. However, when compared to the adult values of its species, the Dikika baby had formed only between 63 and 88 % of the adult brain size, which is lower than that of chimpanzee where by the age of 3 over 90 % of the brain is formed. This relatively slow brain growth observed in A. afarensis is slightly closer to that of humans, pointing to a possible behavioural shift in this species that lived 3.5 million years ago.

Third, the post cranium (the skeleton other than the head) is represented by many bones that carry vital information regarding the locomotion (movement) and height of A. afarensis. The femur (thigh bone), the tibia (shin bone) and the foot of the girl preserve evidence that this ancient species walked upright effectively even at the age of three. However the two shoulder blades are similar to those of gorillas. The fingers are also long and curved as seen in other A. afarensis specimens. This raises old but unanswered questions. While an effective biped when on the ground, A. afarensis probably preserved its capacities for tree climbing which could have been adaptive for sleeping at night and avoiding predators, particularly for the smaller ones.

Fourth, among the rare and exciting discoveries is the hyoid bone. Its morphology in the Dikika girl is similar to that of African great apes and different from that of humans. This bone is unknown from any extinct human ancestor species except for one Neanderthal specimen, and is presumed to have had an important role in human speech development, giving us some clues to understanding the nature and evolution of the human voice box.

Preparation of the new fossil is still in progress. Elements that are discussed here were investigated only partly. Also, it was not possible at this stage to examine many parts of the skeleton, particularly the ribs, the vertebrae and the collar bones and to analyze their relevance to the locomotor behaviour of A. afarensis. After this is done, however, a clear picture of the body plan of baby human ancestors will emerge and will be crucial for addressing questions pertaining to behaviour, body proportions, height and skeletal development in early human ancestors.

Sunday, September 17, 2006

Minority Report Ads

BluScreen, an interactive advertising technology that identifies passers-by using their Bluetooth-enabled cellphones, is being tested at the school of Electronics and Computer Science at Southampton University in the UK.

At the school, the system will chose from different announcements about school events and scheduling. Once out in the real world, the system will present advertisements tailored to individuals.

The BluScreen system has a unique way of determining the ad shown; it holds a microsecond auction in which different advertisers can see the characteristics of the person and then bid on showing an ad. The "winner" of the auction selects the advertisement and pays accordingly.

Obviously, passers-by must have Bluetooth turned on, and profile information marked as available. Participants could influence ad content by the content of their profile.

Developers of the system are interested in having sensors in other parts of the building to build a profile of each individual, to better present them with information (ads) that are relevant to their recent experiences.

Saturday, September 16, 2006

World's First 'Bionic Woman'

The Rehabilitation Institute of Chicago (RIC), the leading physical medicine and rehabilitation hospital in the US, has introduced Claudia Mitchell, the first woman to be successfully fit with RIC's original Bionic Arm technology. The most advanced prosthesis of its kind, the RIC neuro-controlled Bionic Arm allows an amputee to move his or her prosthetic arm as if it is a real limb simply by thinking. The arm also empowers patients with more natural movement, greater range of motion and restores lost function.

The technology was developed by Todd Kuiken, M.D., Ph.D., director of RIC's Neural Engineering Center for Bionic Medicine, and a team of leading rehabilitation experts with the support of grants from the National Institutes of Health (NIH).

To provide the neuro-controlled movement of RIC's Bionic Arm technology, nerves located in the amputee's shoulder, which once went to the amputated arm, are re-routed and connected to healthy muscle in the chest. This surgical process is called targeted muscle reinnervation. The muscle reinnervation procedure allows the re-routed nerves to grow into the chest muscle and direct the signals they once sent to the amputated arm instead to the robotic arm via surface electrodes. Then, when the patient thinks about moving his or her arm, the action is carried out as voluntarily as it would be in a healthy arm allowing for smoother and easier movement of the prosthetic.

In other words, the sensation nerves to the hand have been re-routed to a patch of skin on her chest. Now when Ms. Mitchell is touched on this skin, she feels that her hand is being touched. This will eventually let her 'feel' what she is touching with an artificial hand, as if she were touching it with her own hand.

Currently available artificial arms have only up to three motors. RIC's revolutionary Bionic Arm technology includes a six-motor arm developed in collaboration with researchers around the world. With a six-motor arm, patients have greater motion in the shoulder and forearm and are able to use several parts of the prosthesis simultaneously to produce the more natural arm movements. Using key learnings from the first successful Bionic Arm recipient, former power lineman and double amputee from Tennessee, Jesse Sullivan, Dr. Kuiken and his team also have made significant advancements in the area of sensory feedback so that the patient can actually feel if they are touching hot or cold objects.

Ms. Mitchell, of Ellicott City, Maryland, is a former U.S. Marine Corps officer whose left arm was severed at the scene of a motorcycle accident in 2004. After reading about Mr. Sullivan in a magazine, Ms. Mitchell undertook her own research and was put in touch with Dr. Kuiken. After an evaluation by Dr. Kuiken and his staff, she was found to be a strong candidate and successfully underwent the surgery in 2005.

"RIC is proud to play such a significant role in changing the face of research and advancing technology to improve the lives of individuals with disabilities throughout the world," said Joanne C. Smith, M.D., interim president and CEO of RIC.

Because of the Bionic Arm, Ms. Mitchell has been able to live a more functional and fulfilling life. She is able to give to her passion, the U.S. Marine Corps, through mentoring junior officers and making regular visits to veterans in the amputee units at the National Naval Medical Center and Walter Reed Army Medical Center. Through her volunteer efforts, she shares her message of personal gratitude and hope to troops who have returned from combat in Iraq and Afghanistan.

"Before the surgery, I doubted that I would ever be able to get my life back," said Ms. Mitchell. "But this arm and the Rehabilitation Institute of Chicago have allowed me to return to a life that is more rewarding and active than I ever could have imagined. I am happy, confident and independent. As a military veteran, I am also hopeful that the Bionic Arm technology may provide benefits to amputees returning from war."

Thursday, September 14, 2006

Tiny Fuel Cell Might Replace Batteries In Laptop Computers, Portable Electronics

If you're frustrated by frequently losing battery power in your laptop computer, digital camera or portable music player, then take heart: A better source of "juice" is in the works. Chemists at Arizona State University have created a tiny hydrogen-gas generator that they say can be developed into a compact fuel cell package that can power these and other electronic devices from three to five times longer than conventional batteries of the same size and weight.

The generator uses a special solution containing borohydride, an alkaline compound that has an unusually high capacity for storing hydrogen, a key element that is used by fuel cells to generate electricity. In laboratory studies, a prototype fuel cell made from this generator was used to provide sustained power to light bulbs, radios and DVD players, the researchers say.

The fuel cell system can be packaged in containers of the same size and weight as conventional batteries and is recharged by refilling a fuel cartridge. "We're trying to maximize the usable hydrogen storage capacity of borohydride in order to make this fuel cell power source last longer," says study leader Don Gervasio, Ph.D., a chemist at the University's Biodesign Institute, Center for Applied NanoBioScience. "That could lead to the longest lasting power source ever produced for portable electronics."

One of the challenges in fuel cell development is finding hydrogen-rich compounds for the fuel source. Many different hydrogen sources have been explored for use in fuel cells, including metal hydride "sponges" and liquids such as gasoline, methanol, ethanol and even vegetable oil.

Recently, borohydride has shown promise as a safe, energy-dense hydrogen storage solution. Unlike the other fuel sources, borohydride works at room temperature and does not require high temperatures in order to liberate hydrogen, Gervasio says.

Gervasio and his associates are developing novel chemical additives to increase the useful hydrogen storage capacity of the borohydride solution by as much as two to three times that of simple aqueous sodium borohydride solutions that are currently being explored for fuel cell development. These additives prevent the solution from solidifying, which could potentially clog or damage the hydrogen generator and cause it to fail.

In developing the prototype fuel cell system, the researchers housed the solution in a tiny generator containing a metal catalyst composed of ruthenium metal. In the presence of the catalyst, the borohydride in the water-based solution reacts with water to form hydrogen gas.

The gas leaves the hydrogen generator by moving across a special membrane separating the generator from the fuel cell component. The hydrogen gas then combines with oxygen inside the fuel cell to generate water and electricity, which can then be used to power the portable electronic device. Commercialization of a practical version of this fuel cell could take as many as three to five years, Gervasio says.

Wednesday, September 13, 2006

Strange New Planet

Using a network of small automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta.

"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery.

With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter.

"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1 revolves around its host star every 4.5 days in an orbit one-twentieth of the distance from Earth to the Sun. Once each orbit, it passes in front of its parent star, causing the star to appear fainter by about 1.5 percent for more than two hours, after which the star returns to its previous brightness.

HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated by about 1500 times the Earth-Sun distance. The stars are similar to the Sun but slightly younger - about 3.6 billion years old compared to the Sun's age of 4.5 billion years.

Although stranger than any other extrasolar planet found so far, HAT-P-1 is not alone in its low-density status. The first planet ever found to transit its star, HD 209458b, also is puffed up about 20 percent larger than predicted by theory. HAT-P-1 is 24 percent larger than expected.

"Out of eleven known transiting planets, now not one but two are substantially bigger and lower in density than theory predicts," said co-author Robert Noyes (CfA). "We can't dismiss HD209458b as a fluke. This new discovery suggests something could be missing in our theories of how planets form."

Theorists had already considered a number of possibilities to explain the large size of HD 209458b, but so far without success. The only way to puff up these giant planets beyond the size calculated from planetary structure equations would be to supply additional heat to their interiors. Simple heating of the surface due to the host star's proximity would not work. (If it could, all close-in transiting giant planets should be expanded, not just two of them.)

One way to inject energy into the planet's center is by tipping it on its side, similar to Uranus in the solar system. A planet in that state orbiting close to its star would be subjected to tidal heating of the interior. But according to Smithsonian astronomer Matthew Holman (who was not a member of the discovery team), "the circumstances required to tip over a planet are so unusual that this would seem unlikely to explain both known examples of inflated worlds."

According to co-author Dimitar Sasselov (CfA), "Another explanation for HD 209458b's large size was tidal heating due to an eccentric orbit, but recent observations have pretty much ruled that out."
The scientists will continue observing HAT-P-1 to see if such an explanation could hold in this case, but "until we can find an explanation for both of these swollen planets, they remain a great mystery," Sasselov said.

The HAT network consists of six telescopes, four at the Smithsonian Astrophysical Observatory's Whipple Observatory in Arizona and two at its Submillimeter Array facility in Hawaii. These telescopes conduct robotic observations every clear night, each covering an area of the sky 300 times the size of the full moon with every exposure.

Tuesday, September 12, 2006

How Many Black Holes Are There In The Universe?

Astronomers using ESA's orbiting gamma-ray observatory, Integral, have taken an important step towards estimating how many black holes there are in the Universe.

An international team, lead by Eugene Churazov and Rashid Sunyaev, Space Research Institute, Moscow, and involving scientists from all groups of the Integral consortium used the Earth as a giant shield to watch the number of tell-tale gamma rays from the distant Universe dwindle to zero, as our planet blocked their view.

"Point Integral anywhere in space and it will measure gamma rays," says Pietro Ubertini, INAF, Italy and Principal Investigator on Integral's gamma-ray imager. Most of those gamma rays do not come from nearby sources but from celestial objects so far away that they cannot yet be distinguished as individual sources. This distant gamma-ray emission creates a perpetual glow that bathes the Universe.

Most astronomers believe that the unseen objects are supermassive black holes, millions or billions of times heavier than the Sun and each sitting at the centre of a galaxy. As the black holes swallow matter, the swirling gases release X-rays and gamma rays. Accurately measuring the glow, known as the X-ray and gamma-ray background, is the first step towards calculating how many black holes are contributing to it and how far away in the Universe they are located.
The new Integral observations were made during January and February 2006 and provide highly accurate data on the gamma-ray background. The key to success was using the Earth as a shield.

Allowing the Earth to enter Integral's field of view goes against the standard set of nominal observations for the satellite, because the optical devices needed to determine the spacecraft’s attitude would be blinded by the bright Earth. So, this operation required remarkable efforts from the ISOC/MOC teams operating the mission, who had to rely on alternative spacecraft control mechanisms. But the risk was worth it: by measuring the decrease of the gamma-ray flux once the Earth had blocked Integral's view and by making a model of the Earth’s atmospheric emission, the astronomers precisely gauged the gamma-ray background.

Another bonus of the Integral observations is that the observatory's complementary instruments allowed the strength of both X-rays and gamma rays to be measured simultaneously. In the past, different satellites have had to measure the different energies of X-rays and gamma rays, leaving astronomers with the task of having to piece the results together like the pieces of a jigsaw puzzle.

It is not just the overall glow that Integral has seen. Before the satellite's launch, only a few dozen celestial objects were observed in gamma rays. Now Integral sees about 300 individual sources in our Galaxy and around 100 of the brightest supermassive black holes in other galaxies. These are the tip of the iceberg. Astronomers believe there are tens of millions of active black holes spread throughout space, all contributing to the gamma-ray background. From earlier observations in the softer X-ray band it is known that the soft background radiation is almost entirely populated by Active Galactic Nuclei (AGN). So it is highly likely that these objects are also responsible here at higher Integral energies, even if this is not proven yet.

The next step is for astronomers to programme computer models to calculate how the emission from this unseen population of black holes merges to give the observed glow. These computer models will predict the number and distance of the black holes, and provide insights into the way they behave at the centre of young, middle-aged and old galaxies. Meanwhile, the Integral team will continue to refine their measurements of the perplexing gamma-ray background.

Monday, September 11, 2006

A Plethora of Alien Seas

If life on Earth did indeed spring forth within our vast oceans, then it also might be teeming on thousands of other worlds. New models suggest that as many as one-third of the solar systems in the galactic neighbourhood might contain terrestrial planets with oceans of water that could harbor life.

The new findings counter previous hypotheses on planetary formation, which have claimed that few solar systems contain Earth-like worlds. Part of the problem has to do with so-called hot Jupiters. These gas giants, which orbit closer to their parent stars than Mercury does to the sun, form relatively quickly from the gas in the protoplanetary disk. Astronomers assumed that as these hot Jupiters plow through disk material, they "vacuum up" a lot of the dust and rock or eject it from the solar system. That would leave little material left with which to make water-logged planets.

But "the new models indicate these early ideas were probably wrong," says planetary scientist Sean Raymond of the University of Colorado, Boulder. Raymond and colleagues say they ran simulations lasting more than 8 months each on more than a dozen desktop computers. They observed how nascent solar systems evolved over about 200 million years, basing the initial conditions on current theories of how planets formed in our own solar system. The researchers found that when gas giants migrate, they fling lots of rocky debris away from the star and into the habitable zone, where liquid water can exist on a planet's surface. There, the debris frequently coalesces into Earth-sized planets.

This kind of early evolution also perturbs the disk, causing comets outlying billions of kilometers away to dive toward the star. Enough of these ice balls hit the terrestrial planets to deliver large quantities of water. "We were very surprised to learn that these planets are water-rich and probably covered in global oceans," he says.

The findings suggest that thousands of planetary systems within the Milky Way could harbor Earth-like planets, says Rory Barnes, a planetary scientist at the University of Arizona in Tucson. Still, he cautions that the key question is how many planetary systems have hot Jupiters. The current figures could be an overestimate: Existing exoplanet detection methods are "strongly biased toward" this type of planet, he says, but "strongly biased against" finding solar systems like our own, in which gas giants settle farther away from their parent star.

Sunday, September 10, 2006

Acoustic Data May Reveal Hidden Gas, Oil Supplies

Just as doctors use ultrasound to image internal organs and unborn babies, MIT Earth Resources Laboratory researchers listen to the echoing language of rocks to map what's going on tens of thousands of feet below the Earth's surface.

With the help of a new $580,000 US Department of Energy (DOE) grant, the earth scientists will use their skills at interpreting underground sound to seek out "sweet spots"-pockets of natural gas and oil contained in fractured porous rocks-in a Wyoming oil field. If the method proves effective at determining where to drill wells, it could eventually be used at oil and gas fields across the country.

A major domestic source of natural gas is low-permeability or "tight" gas formations. Oil and gas come from organic materials that have been cooked for eons under the pressure and high heat of the Earth's crust. Some underground reservoirs contain large volumes of oil and gas that flow easily through permeable rocks, but sometimes the fluids are trapped in rocks with small, difficult-to-access pores, forming separate scattered pockets. Until recently, there was no technology available to get at tight gas.

Tight gas is now the largest of three unconventional gas resources, which also include coal beds and shale. Production of unconventional gas in the United States represented around 40 percent of the nation's total gas output in 2004, but could grow to 50 percent by 2030 if advanced technologies are developed and implemented.

One such advanced technology is the brainchild of Mark E. Willis and Daniel R. Burns, research scientists in the Department of Earth, Atmospheric and Planetary Sciences (EAPS), and M. Nafi Toksoz, professor of EAPS. Their method involves combining data from two established, yet previously unrelated, means of seeking out hidden oil and gas reserves.

To free up the hydrocarbons scattered in small pockets from one to three miles below ground, oil companies use a process called hydraulic fracturing, or hydrofrac, which forces water into the bedrock through deep wells to create fractures and increase the size and extent of existing fractures. The fractures open up avenues for the oil and gas to flow to wells.

To monitor the effectiveness of fracturing and to detect natural fractures that may be sweet spots of natural gas, engineers gather acoustic data from the surface and from deep within wells. "Surface seismic methods are like medical ultrasound. They give us images of the subsurface geology," Burns said. Three-dimensional seismic surveys involve creating vibrations on the surface and monitoring the resulting underground echoes. "When the echoes change, fractures are there," Willis said.

A method called time-lapse vertical seismic profiling (VSP) tends to be more accurate because it collects acoustic data directly underground through bore holes. "Putting the receivers down into a well is like making images with sensors inside the body in the medical world," Burns said. "The result is the ability to see finer details and avoid all the clutter that comes from sending sound waves through the skin and muscle tissue to get at the thing we are most interested in seeing."

Time-lapse VSP is expensive and not routinely used in oil and gas exploration. The EAPS research team, working with time-lapse VSP data collected by industry partner EnCana Corp., came up with unique ways to look at the data together with microseismic data from the tiny earthquakes that are produced when the rock is fractured. "If we record and locate these events just as the US Geological Survey does with large earthquakes around the world, we get an idea of where the hydrofrac is located. Then we look at the time-lapse VSP data at those spots and try to get a more detailed image of the fracture," Burns said.

Saturday, September 09, 2006

Modern Humans, Not Neandertals, May Be Evolution's 'Odd Man Out'

It seems that in the great evolutionary "family tree," it is we Modern Humans, not the brow-ridged, large-nosed Neandertals, who are the odd uncle out.

New research published in the August, 2006 journal Current Anthropology by Neandertal and early modern human expert, Erik Trinkaus, Ph.D., professor of anthropology at Washington University in St. Louis, suggests that rather than the standard straight line from chimps to early humans to us with Neandertals off on a side graph, it's equally valid, perhaps more valid based on the fossil record, that the line should extend from the common ancestor to the Neandertals, and Modern Humans should be the branch off that.

Trinkaus has spent years examining the fossil record and began to realize that maybe researchers have been looking at our ancient ancestors the wrong way.

Trinkaus identified fossil traits which seemed to be genetic markers - those not greatly influenced by environment, life ways and wear and tear. He was careful to examine traits that appear to be largely independent of each other to avoid redundancy.

"I wanted to see to what extent Neandertals are derived, that is distinct, from the ancestral form. I also wanted to see the extent to which modern humans are derived relative to the ancestral form," Trinkaus says. "What I came up with is that modern humans have about twice as many uniquely derived traits than do the Neandertals”.

"In the broader sweep of human evolution," says Trinkaus, "the more unusual group is not Neandertals, whom we tend to look at as strange, weird and unusual, but it's us - Modern Humans."

The most unusual characteristics throughout human anatomy occur in Modern Humans, argues Trinkaus. "If we want to better understand human evolution, we should be asking why Modern Humans are so unusual, not why the Neandertals are divergent. Modern Humans, for example, are the only people who lack brow ridges. We are the only ones who have seriously shortened faces. We are the only ones with very reduced internal nasal cavities. We also have a number of detailed features of the limb skeleton that are unique."

Trinkaus admits that every paleontologist will define the traits a little differently. "If you really wanted to, you could make the case that Neandertals look stranger than we do. But if you are reasonably honest about it, I think it would be extraordinarily difficult to make Neandertals more derived than Modern Humans."

Friday, September 08, 2006

A Few Hours Of Thinness For Crude Oil

Offshore oil producers long have dreamed of the technological equivalent of a magic wand: Wave it over pipelines carrying the thick crude oil produced in much of the world, and the oil thins out for just a few hours.

This would allow it to be pumped more easily and economically through pipelines to onshore storage tanks where it would then return to its natural viscous condition.

Rongina Tao and Xiaojun Xu now report development of one such method for reducing the viscosity (thickness) of crude oil.

The method uses a magnetic field to make tiny wax-like particles in paraffin-base crude oil clump together into a smaller number of large particles; an electric field is used to aggregate tiny asphaltene particles in asphalt-base crude oil into large ones. That clumping reduces oil's viscosity for a few hours

Thursday, September 07, 2006

Greenhouse Gas Bubbling From Melting Permafrost Feeds Climate Warming

A study co-authored by a Florida State University scientist and published in the Sept. 7 issue of the journal Nature has found that as the permafrost melts in North Siberia due to climate change, carbon sequestered and buried there since the Pleistocene era is bubbling up to the surface of Siberian thaw lakes and into the atmosphere as methane, a greenhouse gas 20 times more potent than carbon dioxide.

In turn, that bubbling methane held captive as carbon under the permafrost for more than 40,000 years is accelerating global warming by heating the Earth even more - exacerbating the entire cycle. The ominous implications of the process grow as the permafrost decomposes further and the resulting lakes continue to expand, according to FSU oceanography Professor Jeff Chanton and study co-authors at the University of Alaska-Fairbanks.

"This is not good for the quality of human life on Earth," Chanton said.

The researchers devised a novel method of measuring ebullition(bubbling) to more accurately quantify the methane emissions from two Siberian thaw lakes and in so doing, revealed the world's northern wetlands as a much larger source of methane release into the atmosphere than previously believed. The magnitude of their findings has increased estimates of such emissions by 10 to 63 percent.

Understanding the contribution of North Siberia thaw lakes to global atmospheric methane is critical, explains the paper that appears in this week's Nature, because the concentration of that potent greenhouse is highest at that latitude, has risen sharply in recent decades and exhibits a significant seasonal jump at those high northern latitudes.

Chanton points to the thawing permafrost along the margins of the thaw lakes - which comprise 90 percent of the lakes in the Russian permafrost zone - as the primary source of methane released in the region. During the yearlong study, he performed the isotopic analysis and interpretation to determine the methane's age and origin and assisted with measurements of the methane bubbles' composition to shed light on the mode of gas transport.

"My fellow researchers and I estimate that an expansion of these thaw lakes between 1974 and 2000, a period of regional warming, increased methane emissions by 58 percent there," said Chanton. "Because the methane now emitted in our study region dates to the Pleistocene age, it's clear that the process, described by scientists as 'positive feedback to global warming,' has led to the release of old carbon stocks once stored in the permafrost."

Wednesday, September 06, 2006

Nerves Conquer Pain

Several cultures believe that the mind can be harnessed to control aspects of our physiology, such as ramping up the immune system to fight off a cold. Now, this belief has gotten a dose of scientific support from a study that suggests that the central nervous system can regulate pain and even reduce joint damage in arthritic rats.

A team of researchers led by arthritis specialist Gary Firestein of the University of California, San Diego, investigated the influence of the central nervous system in rats with rheumatoid arthritis by blocking a compound made by the spinal cord. The compound, an enzyme called p38 MAP kinase, signals pain and inflammation in rheumatoid arthritis. When the researchers injected a drug into the rats' spines that blocks p38 MAP kinase, swelling in the animals' paws decreased markedly. In addition, rats injected with the drug didn’t respond to ankle pressure, demonstrating reduced pain. Damage to the joints from arthritis was decreased by 60% after spinal injection, compared to untreated animals, the researchers report online 4 September in PLoS Medicine.

Firestein says the findings suggest that the central nervous system senses peripheral tissue inflammation, then activates the p38 pathway. Researchers have previously injected p38 MAP kinase inhibitors into arthritic tissues to control pain and inflammation in animals with some success, but the new work indicates that injecting it into the central nervous system may be more effective, he says. It also hints at a possible biochemical mechanism for the placebo effect, exhibited by about 30% of arthritis sufferers. However, Firestein adds that more work is needed to determine whether placebos prompt the central nervous system to dampen pain via p38 MAP kinase or some other signal.

The study provides pretty convincing evidence that the spinal cord can assuage joint inflammation, at least in rats, says Joan Bathon, director of the Johns Hopkins Arthritis Center in Baltimore, Maryland. But whether p38 MAP kinase inhibitors could be used to treat arthritis in humans is unclear, she says. These compounds have been investigated as arthritis drugs, but none have yet been approved for human use because of harmful side effects. And because the new method requires injection into the spinal column, Bathon says it has a "long way to go" before it becomes clinically useful.

Tuesday, September 05, 2006

Flashing out a Star's Demise

Astronomers may for the first time have caught a star in the act of blowing itself to smithereens. The cataclysmic supernova announced itself by producing an unusually long flash of x-rays. The new find should help researchers better understand the violent deaths of the most massive stars in the universe.
When a rapidly rotating massive star explodes at the end of its life, it leaves a black hole as a corpse. Such explosions blow out jets of matter in two opposite directions and produce brief bursts of energetic gamma rays. These classical gamma ray bursts (GRBs) are the most powerful cosmic explosions since the big bang. Astronomers have long suspected that milder explosions, known as x-ray flashes, are related to GRBs. But it wasn't clear whether x-ray flashes really represent less energetic GRBs or are just normal GRBs seen from a different angle.

The new observation has settled the mystery. On 18 February, NASA's Swift satellite detected a 35-minute x-ray flash now known as XRF 060218(see ultraviolet image above). Immediately, the satellite pointed its x-ray and ultraviolet telescopes toward the explosion, which occurred at an unusually close distance to Earth-a mere 440 million light years away in the constellation Aries the Ram. Ground-based observatories were alerted within minutes, and just a few days later, big telescopes on the ground and in space had a look. "These are by far the best supernova observations ever made," says Swift principal investigator Neil Gehrels of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The analysis of the observations, penned in four papers in this week's issue of Nature, "proves that x-ray flashes and gamma ray bursts share the same origin," says astrophysicist Elena Pian of the University of Trieste, Italy, who co-authored two of the papers. Moreover, the power of the accompanying supernova explosion (catalogued as SN 2006aj) was somewhere between typical supernovas and extremely energetic hypernovas that are associated with GRBs. This suggests there is a whole continuum of related phenomena, says Gehrels, although he admits there's no clue yet why some bursts are less energetic than others.

One team of authors, led by Alicia Soderberg of the California Institute of Technology in Pasadena, suggests that normal supernovas leave a compact neutron star as the explosion remnant, while GRBs leave a black hole. X-ray flashes are somehow in between: They leave a highly magnetized neutron star (known as a magnetar), whose energy produces GRB-like jets of matter moving close to the speed of light, only less energetic.

Another team, lead by Sergio Campana of the Brera Observatory in Merate, Italy, claims it has evidence that Swift actually saw the onset of the star's break-up. But supernova theoretician Adam Burrows of the University of Arizona, Tucson, is doubtful. "It's not clear what has been seen," he says, adding that "a lot more data and much better theories" are needed to finally solve the explosion mechanisms of very massive stars.

Sunday, September 03, 2006

Earth's Poles May Have Wandered

Earth's geographic poles may seem like immovable fixtures, but new evidence suggests that they weren't always where they are now. The findings support an old but controversial theory known as "true polar wander" that states that the poles moved as part of a planetary balancing act millions of years ago.

The idea behind true polar wander is that an unequal distribution of weight in Earth's mantle, the molten layer beneath the crust, would cause the planet to realign itself in relation to its spin axis. For instance, if a large mass such as a super-sized volcano formed away from the equator, the force of Earth's rotation would gradually pull the mass toward the equator. The entire planet would be reoriented, and so the poles-which are defined by where the spin axis passes through the surface-would also move to a new spot on Earth's surface. Something similar may have happened on Mars, where a collection of large volcanoes in the Tharsis region is believed to have caused the planet to realign to its present orientation with Tharsis on the equator.

A team led by geologists Adam Maloof of Princeton University and Galen Halverson of Paul Sabatier University in Toulouse, France, says that Earth indeed rebalanced itself around 800 million years ago during the Precambrian time period. They tested this idea by studying magnetic minerals in sedimentary rocks in a Norwegian archipelago. As the mineral grains were deposited or excreted by microbes, they aligned themselves with Earth's magnetic field. So they act as frozen compasses pointing to an ancient north pole.

Using these minerals, Maloof and Halverson found that the north pole shifted more than 50 degrees-about the current distance between Alaska and the equator-in less than 20 million years. Earth's tectonic plates move much more slowly than that, says Maloof, so the best explanation for this wandering pole is planetary rebalancing. This reasoning is supported by a record of changes in sea level and ocean chemistry in the Norwegian sediments that could be explained by true polar wander, the team reports in the September-October issue of the Geological Society of America Bulletin.

The results match other findings from Australia and China and could help determine how the continents fit together in a single supercontinent known as Rodinia, which existed at the time. But rocks this old are very hard to date accurately and may also have had their magnetic signatures disturbed over time, Van der Voo, of the University of Michigan, Ann Arbor cautions. "This is very tricky stuff," he says.

Ocean Microbe Census Discovers Diverse World Of Rare Bacteria

A startling revelation about the number of different kinds of bacteria in the deep-sea raises fundamental new questions about microbial life and evolution in the oceans.

In a paper published in the USA by the Proceedings of the National Academy of Sciences journal (July 31, online early edition), scientists reveal marine microbial diversity may be some 10 to 100 times more than expected, and the vast majority are previously unknown, low-abundance organisms theorized to play an important role in the marine environment as part of a “rare biosphere.”

“These observations blow away all previous estimates of bacterial diversity in the ocean,” says lead author Mitchell L. Sogin, director of the Marine Biological Laboratory (MBL)’s Josephine Bay Paul Center for Comparative and Molecular Biology and Evolution, located in Woods Hole, Massachusetts.

“Just as scientists have discovered through ever more powerful telescopes that stars number in the billions, we are learning through DNA technologies that the number of marine organisms invisible to the eye exceeds all expectations and their diversity is much greater than we could have imagined.”

“Microbiologists have formally described 5,000 microbial ‘species’,” he says. “This study shows we have barely scratched the surface. Over the last 10 to 20 years, molecular studies have shown there to be more than 500,000 kinds of micro organisms. In our new study, we discovered more than 20,000 in a single liter (about one quart) of seawater, having expected just 1,000 to 3,000.”

“The number of different kinds of bacteria in the oceans could eclipse five to 10 million,” he added.

Dr. Sogin and seven co-authors – from the USA, The Netherlands and Spain – made their discovery using a revolutionary new DNA technique, “454 tag sequencing,” that requires only small snippets of genetic code to identify an organism. They produced as many as 25,000 short DNA sequences for microscopic organisms in each sample from depths of 550 to 4,100 meters (roughly 1,800 to 13,500 feet) at eight Atlantic and Pacific sites. The sampling locations included a hydrothermal vent on an underwater Pacific volcano 480 km (300 miles) off the coast of Oregon, as well as several North Atlantic sites between Greenland and Ireland.

The most unusual sequence tags come from organisms present in low abundance, and these bacteria make up the ‘rare biosphere’. “The detection of these previously overlooked microbes opens a world of new questions about their role in ecological processes and their evolutionary history,” says Dr. Sogin.

The study forms part of the International Census of Marine Microbes (ICoMM), a project of the Census of Marine Life, a 10-year global initiative started in year 2000 that now involves more than 1,700 researchers in over 70 countries in efforts to assess and explain the diversity, distribution, and abundance of life in the oceans -- past, present, and future.

ICoMM funders include the NASA Astrobiology Institute, the Woods Hole Center for Oceans and Human Health (Jointly funded by the National Science Foundation and the National Institute of Environmental Health Sciences), The Earth and Life Science division of the Dutch Science Foundation, and the Alfred P. Sloan Foundation.

“ICoMM has brought together some of the top microbial oceanographers and evolutionary biologists in the world,” says MBL Director Gary G. Borisy. “This discovery by Dr. Sogin and his colleagues demonstrates the value of a collaborative and innovative approach to understanding microscopic life in our oceans.”

Earth’s Most Ancient Life Forms

“Microbes constitute the vast majority of marine biomass and are the primary engines of Earth’s biosphere,” says Dr. Sogin. “They are the oldest life forms, the primary catalysts of energy transformation, and fundamental to the biogeochemical cycles that shape our planetary atmosphere and environment.

“From an evolutionary perspective, they are of pivotal importance. They were the only kinds of life on Earth for approximately 80% of the planet’s history. All multi-cellular life depends upon microbial processes. The microbes can live without us but we are totally dependent upon them for our continued survival.

“Exploration of this newly discovered ‘rare biosphere’ could become a major field of marine biology.”

Says Dr. Sogin: “We know we’re going through global change and micro organisms are vital to our survival. What we do not know is the role of low-abundance microbial populations that have persisted over large evolutionary time scales. We need to understand their diversity and how they work, to anticipate which species can be expected to adapt and how quickly, and to grasp how such other forces as competition and resource availability drive evolutionary change.”

Possible Roles of Rare Microbes in Nature

While a small number of different kinds of bacteria dominated all samples studied, thousands of low-abundance populations represented an overwhelming majority of the novel diversity. Dr. Sogin says: “The most intriguing immediate questions are: How and why do these many different populations of low abundance organisms exist at all; why are they still here?”

“It’s possible these rare organisms are present in high numbers at some locations and their low abundance at other sites is a consequence of diffusion and dispersal. However we believe they must have some importance to the marine ecosystem and can theorize a couple of possible roles.”

One is that they are keystone life forms – micro organisms that exist in low numbers but have some important function within the community, producing perhaps some essential compound.

Alternatively, these rare, low-abundance organisms, which are less prone to predation and direct competition with dominant species, may exist throughout the oceans. If environmental change precludes the growth of dominant populations, members of the rare biosphere may take on new importance in ecosystem processes.

“In other words, the low-abundance organisms might not be very active but represent a reserve of genetic and genomic innovation,” says Dr. Sogin.

“Imagine a world of car manufacturers comprised of giants like Toyota, Ford and Mercedes but with 20,000 other firms making a few vehicles each,” says Jesse Ausubel of New York City, the Census of Marine Life Program Director at the Alfred P. Sloan Foundation. “That is how it seems the mysterious microbial world operates. A swimmer taking just a swallow of seawater may be consuming an entire zoo of 1,000 different forms of bacteria!”

Says co-author Julie Huber of the MBL: “We cannot know the implications of a major, long-term environmental shift if we do not know what species were there to start with. What is rare in one environment may prevail in another. And if major environmental changes do occur, these low-abundance microbes may become dominant.”

Dr. Huber says “454 tag sequencing” provides a fast, relatively low-cost method for fingerprinting marine microbial diversity.

“The depth of sampling conducted is orders of magnitude greater than previously available and reveals the enormous range of genetic diversity of different microbes in the ocean,” she says.

Says co-author Gerhard Herndl of the Netherlands: “Once we catalog the diversity of microbial life in the sea, we can look for patterns and trends in the distribution of organisms. Then we will be able to address how quickly the microbial community can adapt to environmental shifts and what drives evolutionary change.”

The MBL, as part of the ICoMM collaboration, has secured $1.5 million in funding from the W.M. Keck Foundation to analyze our next samples at 1,200 marine sites,” says ICoMM co-chair Jan de Leeuw of the Netherlands. “We will sample surface and mid waters, hydrothermal vents, water near methane seeping from the sea floor, and deep sea sediments. While 1,200 one-liter samples is a drop in the bucket considering the size of the oceans, it represents an important start.”

“Peering through a laboratory microscope into a drop of seawater is like looking at the stars on a clear night”, says marine microbiologist Victor Gallardo of Chile, Vice Chair of the Census of Marine Life. “The ‘454 tag sequencing’ strategy increases resolution like the Hubble Telescope. We can see marine microbial diversity to which we were blind before. These rare, ancient organisms are likely to prove a key part of nature’s history and strategy.”