lunes, 15 de febrero de 2010
The awkward name might be pure old-school Microsoft, but the new Windows 7 Phone Series is more Xbox and Zune than Windows Mobile 6.5. The design team was proportionally one of the biggest for any Microsoft product, and it shows.
The handset I tried is a no-name developer tool, a plain plastic box in which the camera doesn’t line up with the hole in the case, and the capacitive touchscreen doesn’t even meet Microsoft’s own minimum hardware specs for a Windows 7 Phones Series mobile phone. But despite this, the OS itself seems both polished and simple. The UI is very flat, almost all simple, sharp squares and plain text. In fact, it feels like you are looking at the large-print accessibility version.
But despite this simplicity it’s a lot of fun to use. The “hubs” into which content is organized by type are an intuitive way to work, but most of what you do every day can be done without leaving the home screen. IPhone users who live in three or four apps and constantly switch between them for updates from Twitter, e-mail and RSS will be jealous of the dynamic front page. Choose what apps, people, podcasts or almost anything you want on the main screen and they update in real time, with new information swimming sweetly onto the icons. It’s almost like a moving photo in Harry Potter, only less hokey and far more useful.
The phone I tested felt sparse, mostly due to a lack of content, but there was enough on show to appreciate how the hubs work. Hit up a contact in the People hub and you have everything relevant, from their contact details (tap to call) to their Facebook or Twitter status. It’s surprisingly natural.
This is an early iteration, and I couldn’t get any more news from Microsoft about future software. It seems, though, that this hub framework will be the way any other apps will fit into the ecosystem. Hardware, too, will change, and Steve Ballmer mentioned that the software will come on all shapes and sizes of handset.
What surprised me most was that I was expecting yet another iPhone clone. And while the Windows 7 Phone isn’t the huge game changer that the iPhone was upon its debut, it is different enough to embarrass pretty much everyone else except Apple.
Stonehenge may have been surrounded by a "Stonehedge" that blocked onlookers from seeing secret rituals, according to a new study.
Evidence for two encircling hedges—possibly thorn bushes—planted some 3,600 years ago was uncovered during a survey of the site by English Heritage, the government agency responsible for maintaining the monument in southern England.
The idea that Stonehedge was a shield against prying eyes isn’t yet firmly rooted, but it's archaeologists' leading theory. For instance the newfound banks are too low and unsubstantial to have had a defensive role.
"The best [theory] we can come up with is some sort of hedge bank," said English Heritage archaeologist David Field, whose team discovered the two landscape features in April 2009.
"We think they served as some sort of screen to filter access to the center [of Stonehenge]." (See Stonehenge pictures.)
The shallow earthworks—each runs inside a ring of known Bronze Age pits—are just visible to an expert eye, "but you need to get down on your hands and knees" to see them, Field added.
The archaeologists didn't find any physical evidence of vegetation, but the shallow features resemble former hedge banks that are seen around formerly hedged fields.
While there’s no firm evidence for a British prehistoric landscape-gardening tradition, there's evidence for tree cultivation at the time Stonehenge was in use.
"It seems standard-size trees were being cultivated and looked after in order to provide straight, telegraph-pole-like features for the construction of palisades [fences of defensive stakes] and so on," Field said.
With that in mind, Stonehedge's "vegetation screens are quite feasible," Field said. "Something like thorn bushes … or small trees."
Past archaeological investigations at Stonehenge have tended to focus chiefly on the stones themselves, he noted.
"To date nobody has really considered the vegetation around the stones."
(Related: "Mini-Stonehenge Found: Crematorium on Stonehenge Road?")
The latest finds, reported in the March/April edition of British Archaeology magazine, come "completely out of the blue," according to editor Mike Pitts, an archaeologist and Stonehenge expert.
The magazine, a publication of the Council for British Archaeology, often publishes archaeologist-written reports on new finds.
While Pitts thinks the hedge theory is "a perfectly reasonable explanation … there have been no excavations of these features, so until that happens we won’t really know what’s going on."
The April 2009 landscape survey employed advanced equipment, such as high-resolution surface lasers, to discern shapes invisible to the human eye.
"Believe it or not, it's the first earthworks survey of the monument since 1919," Pitts added. "Unsurprisingly, all sorts of things were found."
Those include a flattened mound near the center of Stonehenge, which may be a burial. The Stonehenge area is littered with prehistoric burial mounds, and the monument itself likely served first and foremost as a cemetery, experts say.
Partially concealed by fallen stones, the forgotten mound had been previously recorded in 18th- and 19th-century watercolor paintings.
"There’s a good chance it's prehistoric," said English Heritage's Field.
The suspected burial mound possibly dates to the earliest phases of the monument, as early as 5,000 years ago, Field said.
If the mound was built first, "it may be that this was the focus around which Stonehenge developed."
In research that gives literal meaning to the term "power suit," University of California, Berkeley, engineers have created energy-scavenging nanofibers that could one day be woven into clothing and textiles.
These nano-sized generators have "piezoelectric" properties that allow them to convert into electricity the energy created through mechanical stress, stretches and twists.
"This technology could eventually lead to wearable 'smart clothes' that can power hand-held electronics through ordinary body movements," said Liwei Lin, UC Berkeley professor of mechanical engineering and head of the international research team that developed the fiber nanogenerators.
Because the nanofibers are made from organic polyvinylidene fluoride, or PVDF, they are flexible and relatively easy and cheap to manufacture.
Although they are still working out the exact calculations, the researchers noted that more vigorous movements, such as the kind one would create while dancing the electric boogaloo, should theoretically generate more power. "And because the nanofibers are so small, we could weave them right into clothes with no perceptible change in comfort for the user," said Lin, who is also co-director of the Berkeley Sensor and Actuator Center at UC Berkeley.
The fiber nanogenerators are described in this month's issue of Nano Letters, a peer-reviewed journal published by the American Chemical Society.
The goal of harvesting energy from mechanical movements through wearable nanogenerators is not new. Other research teams have previously made nanogenerators out of inorganic semiconducting materials, such as zinc oxide or barium titanate. "Inorganic nanogenerators -- in contrast to the organic nanogenerators we created -- are more brittle and harder to grow in significant quantities," Lin said.
The tiny nanogenerators have diameters as small as 500 nanometers, or about 100 times thinner than a human hair and one-tenth the width of common cloth fibers. The researchers repeatedly tugged and tweaked the nanofibers, generating electrical outputs ranging from 5 to 30 millivolts and 0.5 to 3 nanoamps.
Furthermore, the researchers report no noticeable degradation after stretching and releasing the nanofibers for 100 minutes at a frequency of 0.5 hertz (cycles per second).
Lin's team at UC Berkeley pioneered the near-field electrospinning technique used to create and position the polymeric nanogenerators 50 micrometers apart in a grid pattern. The technology enables greater control of the placement of the nanofibers onto a surface, allowing researchers to properly align the fiber nanogenerators so that positive and negative poles are on opposite ends, similar to the poles on a battery.
Without this control, the researchers explained, the negative and positive poles might cancel each other out and reducing energy efficiency.
The researchers demonstrated energy conversion efficiencies as high as 21.8 percent, with an average of 12.5 percent.
"Surprisingly, the energy efficiency ratings of the nanofibers are much greater than the 0.5 to 4 percent achieved in typical power generators made from experimental piezoelectric PVDF thin films, and the 6.8 percent in nanogenerators made from zinc oxide fine wires," said the study's lead author, Chieh Chang, who conducted the experiments while he was a graduate student in mechanical engineering at UC Berkeley.
"We think the efficiency likely could be raised further," Lin said. "For our preliminary results, we see a trend that the smaller the fiber we have, the better the energy efficiency. We don't know what the limit is."
Other co-authors of the study are Yiin-Kuen Fuh, a UC Berkeley graduate student in mechanical engineering; Van H. Tran, a graduate student at the Technische Universität München (Technical University of Munich) in Germany; and Junbo Wang, a researcher at the Institute of Electronics at the Chinese Academy of Sciences in Beijing, China.
The National Science Foundation and the Defense Advanced Research Projects Agency helped support this research.
Beyond the Abyss: Deep Sea Creatures Build Their Homes from Materials That Sink from Near the Ocean Surface
Evidence from the Challenger Deep -- the deepest surveyed point in the world's oceans -- suggests that tiny single-celled creatures called foraminifera living at extreme depths of more than ten kilometres build their homes using material that sinks down from near the ocean surface.
The Challenger Deep is located in the Mariana Trench in the western Pacific Ocean. It lies in the hadal zone beyond the abyssal zone, and plunges down to a water depth of around 11 kilometres.
"The hadal zone extends from around six kilometres to the deepest seafloor. Although the deepest parts of the deepest trenches are pretty inhospitable environments, at least for some types of organism, certain kinds of foraminifera are common in the bottom sediments," said Professor Andrew Gooday of the National Oceanography Centre, Southampton (NOCS) and member of a UK-Japanese team studying these organisms in samples collected in 2002 during a Japan-USA-Korea expedition to study life in the western depression of the Challenger Deep.
The researchers, whose findings appear in the latest issue of the journal Deep Sea Research, used the remotely operated vehicle KAIKO, operated by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), to take core samples from the soft sediment of the trench floor. Among many foraminiferans with an organic shell (or 'test'), they found four undescribed specimens with agglutinated tests.
"The Challenger Deep is an extreme environment for agglutinated foraminifera, which construct their tests from a wide range of particles cemented together by calcareous or organic matter," said Gooday. "At these great depths, particles made from biologically formed calcite and silica, as well as minerals such as quartz, should dissolve, leaving only clay grains available for test building."
The researchers were therefore surprised to discover that foraminiferan tests sampled from the Challenger Deep contained calcareous components, including the dissolved remnants of coccoliths, the calcium carbonate plates of tiny algae called coccolithophores, and planktonic foraminiferan test fragments.
The organic test surface of one species was densely pitted with imprints, which the researchers interpreted as representing mineral grains of various types, including quartz, which subsequently dissolved. Agglutinated particles, presumed to be clay minerals, survived only in one specimen.
"Our observations demonstrate that coccoliths, and probably also planktonic foraminiferan tests, reach the Challenger Deep intact," said Gooday. "These particles were probably transported to these extreme depths in rapidly sinking marine snow, the aggregated remains of phytoplankton that lived in the sunlit surface ocean, or in faecal pellets from zooplankton."
It seems likely, therefore, that at least some agglutinated foraminifera living at extreme hadal depths build their homes from material that sinks down from the ocean above, rather like manna from heaven.
This study was supported by the Japan Society for the Promotion of Science and the OCEANS 2025 Strategic Research Programme of the UK Natural Environment Research Council.
The researchers are Andrew Gooday (NOCS), K. Uematsu (Marine Works Japan Ltd, Yokosuka, Japan), H. Kitazato & T. Toyofuku (JAMSTEC), and J. R. Young (Natural History Museum, London).
Material scientists at the Nano/Bio Interface Center of the University of Pennsylvania have demonstrated the transduction of optical radiation to electrical current in a molecular circuit. The system, an array of nano-sized molecules of gold, respond to electromagnetic waves by creating surface plasmons that induce and project electrical current across molecules, similar to that of photovoltaic solar cells.
The results may provide a technological approach for higher efficiency energy harvesting with a nano-sized circuit that can power itself, potentially through sunlight. Recently, surface plasmons have been engineered into a variety of light-activated devices such as biosensors.
It is also possible that the system could be used for computer data storage. While the traditional computer processor represents data in binary form, either on or off, a computer that used such photovoltaic circuits could store data corresponding to wavelengths of light.
Because molecular compounds exhibit a wide range of optical and electrical properties, the strategies for fabrication, testing and analysis elucidated in this study can form the basis of a new set of devices in which plasmon-controlled electrical properties of single molecules could be designed with wide implications to plasmonic circuits and optoelectronic and energy-harvesting devices.
Dawn Bonnell, a professor of materials science and the director of the Nano/Bio Interface Center at Penn, and colleagues fabricated an array of light sensitive, gold nanoparticles, linking them on a glass substrate. Minimizing the space between the nanoparticles to an optimal distance, researchers used optical radiation to excite conductive electrons, called plasmons, to ride the surface of the gold nanoparticles and focus light to the junction where the molecules are connected. The plasmon effect increases the efficiency of current production in the molecule by a factor of 400 to 2000 percent, which can then be transported through the network to the outside world.
In the case where the optical radiation excites a surface plasmon and the nanoparticles are optimally coupled, a large electromagnetic field is established between the particles and captured by gold nanoparticles. The particles then couple to one another, forming a percolative path across opposing electrodes. The size, shape and separation can be tailored to engineer the region of focused light. When the size, shape and separation of the particles are optimized to produce a "resonant" optical antennae, enhancement factors of thousands might result.
Furthermore, the team demonstrated that the magnitude of the photoconductivity of the plasmon-coupled nanoparticles can be tuned independently of the optical characteristics of the molecule, a result that has significant implications for future nanoscale optoelectronic devices.
"If the efficiency of the system could be scaled up without any additional, unforeseen limitations, we could conceivably manufacture a one-amp, one-volt sample the diameter of a human hair and an inch long," Bonnell said.
The study, published in the current issue of the journal ACS Nano, was conducted by Bonnell, David Conklin and Sanjini Nanayakkara of the Department of Materials Science and Engineering in the School of Engineering and Applied Science at Penn; Tae-Hong Park of the Department of Chemistry in the School of Arts and Sceicnes at Penn; Parag Banerjee of the Department of Materials Science and Engineering at the University of Maryland; and Michael J. Therien of the Department of Chemistry at Duke University.
This work was supported by the Nano/Bio Interface Center, National Science Foundation, the John and Maureen Hendricks Energy Fellowship and the U.S. Department of Energy.
martes, 9 de febrero de 2010
Northwestern University researchers are the first to design a bioactive nanomaterial that promotes the growth of new cartilage in vivo and without the use of expensive growth factors. Minimally invasive, the therapy activates the bone marrow stem cells and produces natural cartilage. No conventional therapy can do this.
The results will be published online the week of Feb. 1 by the Proceedings of the National Academy of Sciences (PNAS).
"Unlike bone, cartilage does not grow back, and therefore clinical strategies to regenerate this tissue are of great interest," said Samuel I. Stupp, senior author, Board of Trustees Professor of Chemistry, Materials Science and Engineering, and Medicine, and director of the Institute for BioNanotechnology in Medicine. Countless people -- amateur athletes, professional athletes and people whose joints have just worn out -- learn this all too well when they bring their bad knees, shoulders and elbows to an orthopaedic surgeon.
Damaged cartilage can lead to joint pain and loss of physical function and eventually to osteoarthritis, a disorder with an estimated economic impact approaching $65 billion in the United States. With an aging and increasingly active population, this is expected to grow.
"Cartilage does not regenerate in adults. Once you are fully grown you have all the cartilage you'll ever have," said first author Ramille N. Shah, assistant professor of materials science and engineering at the McCormick School of Engineering and Applied Science and assistant professor of orthopaedic surgery at the Feinberg School of Medicine. Shah is also a resident faculty member at the Institute for BioNanotechnology in Medicine.
Type II collagen is the major protein in articular cartilage, the smooth, white connective tissue that covers the ends of bones where they come together to form joints.
"Our material of nanoscopic fibers stimulates stem cells present in bone marrow to produce cartilage containing type II collagen and repair the damaged joint," Shah said. "A procedure called microfracture is the most common technique currently used by doctors, but it tends to produce a cartilage having predominantly type I collagen which is more like scar tissue."
The Northwestern gel is injected as a liquid to the area of the damaged joint, where it then self-assembles and forms a solid. This extracellular matrix, which mimics what cells usually see, binds by molecular design one of the most important growth factors for the repair and regeneration of cartilage. By keeping the growth factor concentrated and localized, the cartilage cells have the opportunity to regenerate.
Together with Nirav A. Shah, a sports medicine orthopaedic surgeon and former orthopaedic resident at Northwestern, the researchers implanted their nanofiber gel in an animal model with cartilage defects.
The animals were treated with microfracture, where tiny holes are made in the bone beneath the damaged cartilage to create a new blood supply to stimulate the growth of new cartilage. The researchers tested various combinations: microfracture alone; microfracture and the nanofiber gel with growth factor added; and microfracture and the nanofiber gel without growth factor added.
They found their technique produced much better results than the microfracture procedure alone and, more importantly, found that addition of the expensive growth factor was not required to get the best results. Instead, because of the molecular design of the gel material, growth factor already present in the body is enough to regenerate cartilage.
The matrix only needed to be present for a month to produce cartilage growth. The matrix, based on self-assembling molecules known as peptide amphiphiles, biodegrades into nutrients and is replaced by natural cartilage.
The National Institutes of Health and the company Nanotope supported the research.
Jupiter's volcanic moon Io, as seen by the Voyager 1 spacecraft.
Oceans of lava might bubble on its surface. Hot pebbles may rain down from the sky. But the extrasolar planet CoRoT-7b is considered to be the most Earthlike world yet found outside our solar system.
A recent study, however, suggests that Earth might not be the best basis for comparison. Instead, the authors argue, CoRoT-7b is the first in a new class of exoplanets: a super-Io.
Like Jupiter's moon Io, CoRoT-7b could easily be in the right kind of orbit to experience what's known as tidal heating, according to study co-author Rory Barnes of the University of Washington in Seattle.
On Io, tidal heating is a result of the crust being constantly deformed by the push and pull of Jupiter's gravity. This action generates enough internal heat to drive hundreds of active volcanoes—and the same could be true for CoRoT-7b, Barnes said.
But unlike Io, CoRoT-7b closely orbits a star, not a planet, so tides aren't its only source of heat. Based on previous observations, astronomers know that CoRoT-7b's surface is between 1,832 and 2,732 degrees Fahrenheit (1,000 and 1,500 degrees Celsius).
That's hot enough for there to be "ponds or possibly even oceans of magma," Barnes said. Scientists also know that the planet is tidally locked, which means that only one side ever faces the star.
"There could be volcanism on the back side of the planet," Barnes said. "It could be that on one side the surface is molten, and on the other side there's raging volcanoes."
Planet More Like Io Than Earth
CoRoT-7b was found using the French-led planet-hunting mission CoRoT, which looks for periodic dips in starlight caused by orbiting bodies passing in front of—transiting—a star, as seen from Earth.
When CoRoT-7b's discovery was announced in February 2009, astronomers hailed the world as the smallest exoplanet yet found orbiting a sunlike star.
From CoRoT-7b's transits, astronomers could tell that the planet is about twice the size of Earth, which is approximately 7,920 miles (12,760 kilometers) wide. Io measures roughly 2,260 miles (3,630 kilometers) across.
Later studies measured CoRoT-7b's mass and density and confirmed that the planet is rocky. Based on these characteristics, CoRoT-7b was dubbed a super-Earth.
The term is one of a handful—such as "hot Jupiter" and "super-Neptune"—being used to informally classify exoplanets based on how closely they resemble worlds in our solar system.
In the recent study, presented last month at a meeting of the American Astronomical Society, Barnes and colleagues looked at the possible orbits for CoRoT-7b based on its size and mass, its proximity to its star, and its interactions with a nearby sister planet, CoRoT-7c.
The researchers found that even a slight eccentricity in CoRoT-7b's orbit would generate enough tidal heating to spawn bunches of volcanoes, making the planet much more Io-like than Earthlike.
For starters, just as Io circles close to massive Jupiter, CoRoT-7b orbits very close to its host star, so the influence of gravity is especially strong, Barnes said.
What's more, both Io and CoRoT-7b are tidally locked. In Io's case, this means that one side always faces Jupiter. That side of the moon is being tugged so much harder by gravity that the otherwise round world becomes slightly elongated, with a bulge around the middle.
"Earth does this—we have a tidal bulge due to interactions with the sun and our moon," Barnes noted. "The ocean tides are the result of [gravitational] tides, but rock is also distorted due to tidal effects."
In addition, Io maintains an irregular, elliptical orbit due to interactions with other Jovian moons close by, so its distance to Jupiter changes over time. As Io gets closer to Jupiter, it becomes more elongated, and as it moves away it becomes more spherical.
"If you had a tennis ball and you kept squeezing it, you would get heat from friction," Barnes said. "For Io it's like that, except you're doing it to a planet."
Look for the Gases?
For now, CoRoT-7b is too distant to allow for current techniques and telescopes to accurately trace the planet's orbit, so whether the world truly resembles Io remains a mystery.
But "I think they have a pretty good case," said Rosaly Lopes, a planetary scientist with NASA's Jet Propulsion Laboratory in Pasadena, California.
After all, volcanism on Io had been predicted shortly before the Voyager spacecraft actually spotted the moon's volcanic plumes in 1979, she said. (See a picture of a giant plume on Io.)
"Stan Peale and colleagues ... analyzed the orbit of Io and said it would have tidal heating," Lopes said. The very next week, pictures from Voyager revealed about a dozen plumes, and later images from the Galileo spacecraft found more than 170 active volcanoes.
Peale, now a professor emeritus at the University of California, Santa Barbara, agreed that "the authors' conclusions are viable," noting that the presence of a second planet near CoRoT-7b means that the planet's orbit could vary "sufficiently to heat the interior to a super-Io state, leading to Io-like volcanic surface activity."
According to JPL's Lopes, "what's interesting here is that they're showing worlds like Io probably exist in other solar systems. But whether [CoRoT-7b] actually has active volcanism at the moment is going to be very difficult to prove."
It's possible spacecraft such as the Spitzer Space Telescope could see gases coming from CoRoT-7b's volcanoes, study author Barnes said.
"It might have a huge cloud of volcanic gases orbiting the planet. We could maybe see it in [light signatures] using Spitzer, but that would be very hard, because the planet is so far and so faint."
Overall, Barnes thinks similarly hot, rocky worlds will start turning up in the tens of hundreds as current planet-hunting missions such as CoRoT and the recently launched Kepler spacecraft peer deeper into the sky. (Related: "Five New Planets Found; Hotter Than Molten Lava.")
"I think of Kepler as a super-Io detector," Barnes said. And each super-Io found will be "a stepping stone to finding real super-Earths."
A new species of prehistoric croc has been unearthed in Colombia—and the ancient reptile was likely prey for the largest known snake ever to have slithered the Earth, a new study says.
But if you're hoping for a prehistoric clash of the titans, you're out of luck: The 7-foot-long (2.1-meter-long) crocodile relative—called Cerrejonisuchus improcerus—wouldn't have stood a fighting chance against the 45-foot-long (13.7-meter-long) Titanoboa cerrejonesis, researchers say.
There would have been "no competition whatsoever," said study leader Alex Hastings, a University of Florida graduate student in vertebrate paleontology who works with the school's the Florida Museum of Natural History.
"Even the smallest Titanoboa ... would have no problem downing even the largest of the new crocodilyforms we found." Crocodilyforms are reptiles that belong to the order Crocodilia, which includes, crocodiles, alligators, caimans (picture), and gavials, among other species.
Fossils of the snake and the newfound crocodile relative were found next to each other between 2004 and 2007 in an open-pit coal mine in northeastern Colombia—a "remarkable" fossil site, Hastings said.
Both reptiles lived in South America 60 million years ago, when the local environment was on the cusp of transitioning into the continent's well-known modern rain forests.
The fossil site is "one of the first glimpses of the beginning of the ecosystem that we have today," Hastings said.
Titanoboa's Big Squeeze
In addition to finding the creatures side by side, the case for snake vs. crocodyliform battles is strengthened by the behavior of the animals' modern descendants, according to the study, published January 28 in the Journal of Vertebrate Paleontology.
For instance, modern anacondas in the Amazon—including the current titleholder for world's biggest snake, the green anaconda—often eat living members of the croc family, such as caimans.
Like these snakes, Titanoboa probably waited by the water's edge to catch C. improcerus off guard before squeezing the "little guy" to death, Hastings said. "It was not a good end for the poor crocodyliform."
When it managed to avoid Titanoboa's grasp, C. improcerus likely munched on tiny snakes, frogs, lizards, and mammals. The crocodile relative was the smallest of its family, the dyrosaurids, and had an unusually short snout, seemingly adapted to nabbing critters that would have been ignored by bigger crocodyliforms.
As for Titanoboa—the largest land animal during that time—the research gives another hint at the massive snake's power, Hastings added.
"It's fleshing out that story of what [these] reptiles were capable of."