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Communities are groups that are densely connected among their members, and sparsely connected with the rest of the network. Community structure can reveal abundant hidden information about complex networks that is not easy to detect by simple observation. There are many large-scale complex networks (systems) in the real world whose structure is not fully understood. A great deal of research has been carried out to uncover the structures of these real world networks, to improve the ability to manage, maintain, renovate and control them. With the help of varied approaches, it is possible to shed light on the general structure of these networks, and further understand their function.
Network science methods have been used in various settings1, 2, including social3, 4, information5, transportation6, energy7, ecological8, disease9, and biological networks10, 11, 12,13. In most of these cases we can find clear community structures, which are usually associated with specific functions. However, to date, most detection methods have limitations, and there is still a lot of room to develop more general approaches.
At present, most methods focus on the detection of node community. One popular approach is based on the optimization of the modularity Q14, 15, 52, 56 of a sub-network. Some methods13, 14,29, 34, 38, 39, 40 force every node to be assigned to a single community. This assumption doesn't always reflect real world networks, where several overlapping communities can co-exist. For example, in social networks, a person may have family relationship circles, job circles, friend circles, social circles, hobby circles and so on. Algorithms that can discover overlapping communities16, 17, 18, 19, 20, 21, 22, 23 have been developed, and recently, methods to detect link communities20, 24, 25 have been presented. The concept of a link community is useful for discovering overlapping communities, as edges are more likely to have unique identities than nodes, which instead tend to have multiple identities. In addition, statistical54, information-theoretic35, 48, 53 and synchronization and dynamical clustering approaches49, 50, 58, 59, 60have also been developed to detect communities.
The interactive map produced by researchers from Oxford University and UCL (University College London), details the histories of genetic mixing between each of the 95 populations across Europe, Africa, Asia and South America spanning the last four millennia.
The study, published this week in Science, simultaneously identifies, dates and characterises genetic mixing between populations. To do this, the researchers developed sophisticated statistical methods to analyse the DNA of 1490 individuals in 95 populations around the world. The work was chiefly funded by the Wellcome Trust and Royal Society.
'DNA really has the power to tell stories and uncover details of humanity's past,' said Dr Simon Myers of Oxford University's Department of Statistics and Wellcome Trust Centre for Human Genetics, co-senior author of the study.
'Because our approach uses only genetic data, it provides information independent from other sources. Many of our genetic observations match historical events, and we also see evidence of previously unrecorded genetic mixing. For example, the DNA of the Tu people in modern China suggests that in around 1200CE, Europeans similar to modern Greeks mixed with an otherwise Chinese-like population. Plausibly, the source of this European-like DNA might be merchants travelling the nearby Silk Road.'
The powerful technique, christened 'Globetrotter', provides insight into past events such as the genetic legacy of the Mongol Empire. Historical records suggest that the Hazara people of Pakistan are partially descended from Mongol warriors, and this study found clear evidence of Mongol DNA entering the population during the period of the Mongol Empire. Six other populations, from as far west as Turkey, showed similar evidence of genetic mixing with Mongols around the same time.
'What amazes me most is simply how well our technique works,' said Dr Garrett Hellenthal of the UCL Genetics Institute, lead author of the study. 'Although individual mutations carry only weak signals about where a person is from, by adding information across the whole genome we can reconstruct these mixing events. Sometimes individuals sampled from nearby regions can have surprisingly different sources of mixing.
'For example, we identify distinct events happening at different times among groups sampled within Pakistan, with some inheriting DNA from sub-Saharan Africa, perhaps related to the Arab Slave Trade, others from East Asia, and yet another from ancient Europe. Nearly all our populations show mixing events, so they are very common throughout recent history and often involve people migrating over large distances.'
The team used genome data for all 1490 individuals to identify 'chunks' of DNA that were shared between individuals from different populations. Populations sharing more ancestry share more chunks, and individual chunks give clues about the underlying ancestry along chromosomes.
'Each population has a particular genetic 'palette', said Dr Daniel Falush of the Max Planck Institute for Evolutionary Anthropology in Leipzig, co-senior author of the study.
'If you were to paint the genomes of people in modern-day Maya, for example, you would use a mixed palette with colours from Spanish-like, West African and Native American DNA. This mix dates back to around 1670CE, consistent with historical accounts describing Spanish and West African people entering the Americas around that time. Though we can't directly sample DNA from the groups that mixed in the past, we can capture much of the DNA of these original groups as persisting, within a mixed palette of modern-day groups. This is a very exciting development.'
A map captures the Martian craters, valleys and peaks in stunning detail and offers ideas on where the rovers of the future might land.
What really lies across the surface of Mars? Rovers have scurried about the red planet for years, drilling, scooping and analyzing for signs of life, past or present. But to really understand the Martian landscape, scientists need to look at the entire surface. What they have needed is a global geologic map. The red planet is long overdue for a new one. The last major effort in Martian cartography was published in 1987, scraped together from the early Viking probes’ scant images and datasets. Since then, four additional orbiters with superior imaging capabilities have journeyed into Martian orbit, collected data and transmitted their findings back to Earth.
Now, scientists at the United States Geological Survey have used that data to create an updated map of the entire Martian surface. The new map shows that ancient rock — dating back billions of years ago, when Mars’s environmental conditions might have closely resembled Earth’s— exists in many more locations than previously thought. Because the map highlights the location of the oldest rocks on Mars, it could help future missions chart a course for these areas.
“We are disproportionately interested in the early part of Martian history,” said David Beaty, the chief scientist for the Mars Exploration Directorate at the Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the research. “It was during that period that more water would have been around, which is one of the key aspects of the origin of life.”
The project, funded by NASA, was not simply a compilation of photographs from Martian orbit. Recent probes, such as the Mars Global Surveyorlaunched in 1996, were outfitted with advanced topographical instruments that helped cartographers pinpoint the subtler features of the Martian landscape.
Flood. Drought. Heat waves. Ice melt. The impact of a warming world is being manifested in a variety of ways, and we can see it from space. Browse through our gallery of pictures taken by NASA satellites looking down at planet Earth.
Less than a year after a devastating 2003 heat wave killed over 37,000 people across Europe, another heat wave struck the region. On July 1, 2004, this image from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) recorded land surface temperatures of 138°F (59°C) in Spain. In this false-color image, red represents the warmest temperatures, yellow is intermediate, and light and dark blue are progressively cooler. Air temperatures in both countries soared over 104°F (40°C). Three days after this image was taken, Spain set a new air temperature record for the nation: 117°F (47°C). Climate models predict more extreme weather events, including heat waves, in the coming decades due to man-made climate change.
Found at the intersection of four different countries in West Africa, Lake Chad was once one of the African continent's largest bodies of fresh water, close in surface area to North America's Lake Erie. But today it is a ghost of its former self, reduced to only about 1/20th its former size in just four decades, thanks to prolonged drought and human demand for water.
A warming world also makes heavily populated coastal areas more vulnerable to flooding: higher global temperatures produce warmer seawater, which expands and causes a rise in sea level. Approximately 400 million people live within 20 meters (0.01 miles) of sea level and 20 km (12 miles) of a coast; modest increases in sea level could displace millions of people.
Wildfire activity in the western U.S. has increased markedly since the mid-1980s, with more frequent large fires and longer fire seasons. Climate models predict increased wildfire risk across many areas of the globe in coming decades.
New research by theorists at the Harvard-Smithsonian Center for Astrophysics(CfA) shows that we could spot the fingerprints of certain pollutants under ideal conditions. This would offer a new approach in the search for extraterrestrial intelligence (SETI).
“We consider industrial pollution as a sign of intelligent life, but perhaps civilizations more advanced than us, with their own SETI programs, will consider pollution as a sign of unintelligent life since it’s not smart to contaminate your own air,” said Harvard student and lead author Henry Lin.
“People often refer to ETs as ‘little green men,’ but the ETs detectable by this method should not be labeled ‘green’ since they are environmentally unfriendly,” added co-author Avi Loeb, Harvard’s Frank B. Baird Jr. Professor of Science.
The team, which also includes Smithsonian scientist Gonzalo Gonzalez Abad, finds that the upcoming James Webb Space Telescope (JWST) should be able to detect two kinds of chlorofluorocarbons (CFCs) — ozone-destroying chemicals used in solvents and aerosols. They calculated that JWST could tease out the signal of CFCs if atmospheric levels were 10 times those on Earth. A particularly advanced civilization might intentionally pollute the atmosphere to high levels and globally warm a planet that is otherwise too cold for life.
There is one big caveat to this work. JWST can only detect pollutants on an Earth-like planet circling a white dwarf star, which is what remains when a star like our sun dies. That scenario would maximize the atmospheric signal. Finding pollution on an Earth-like planet orbiting a sun-like star would require an instrument beyond JWST — a next-next-generation telescope.
The team notes that a white dwarf might be a better place to look for life than previously thought, since recent observations found planets in similar environments. Those planets could have survived the bloating of a dying star during its red giant phase, or have formed from the material shed during the star’s death throes.
The Chairman and CEO of DNA Electronics, a provider of point-of-care genomic diagnostics solutions for medical and healthcare applications, Chris Toumazou, has been awarded the European Inventor Award 2014 in the Research category, for his rapid USB-based DNA testing device.
Announced at the European Inventor Awards ceremony in Berlin on June 17th 2014, Toumazou’s win recognises his contribution to medical research with his ground-breaking invention. The device, which can show the results of a DNA test within minutes, uses silicon transistors to identify DNA and RNA, offering a simpler, cheaper and more discrete alternative to existing DNA analysis equipment.
The invention involves the amplification and detection of DNA and other biomolecules using pH measurement, providing the ground work for DNA Electronics’ molecular diagnostics platform Genalysis®. With the capability of identifying genomic sequences, not only in patients, but also in infectious agents, the company is developing products that will provide clinicians with rapid actionable diagnosis of life-threatening conditions.
DNA Electronicsis a developer of semiconductor solutions for real-time nucleic acid detection which enables faster, simpler and more cost-effective DNA analysis platforms.
A spin-out of Imperial College London, DNA Electronics was founded by Professor Toumazou following his invention of the company’s core technology that allows CMOS transistors to be switched on and off with DNA – the key invention enabling semiconductor-based sequencing. Prof. Toumazou’s innovation has culminated in the world’s first DNA logic on standard CMOS technology.
The company’s IP portfolio includes techniques for monitoring nucleotide insertions using ion-sensitive transistors, enabling label-free electronic DNA sequencing and diagnostics platforms. DNA Electronics (DNAe) has developed the ground-breaking Genalysis® platform of disposable silicon chip-based solutions for real-time nucleic acid sequence detection at the point of care, providing end users with technology as yet unavailable outside a laboratory.
DNA Electronics has a non-exclusive, field-limited licensing agreement with Ion Torrent (now part of Thermo Fisher Scientific), whose next generation sequencing technology is based on DNA Electronics’ semiconductor sequencing IP. DNA Electronics has also licensed its Genalysis® technology platform to GENEU™, a company that is delivering on-the-spot genetic analytics services for cosmetics and skincare applications.
A team of researchers with members from several countries working together in Rome, Italy, has come up with a new explanation of how it is that starlings are able to fly in a flock in a way that makes them appear as a single organism. In their paper published in the journal Nature Physics, the team describes how they used high-speed cameras to capture and study flight movement by individual bird members and what they found as a result.
Starling flight is as mesmerizing as it is mystifying—flocks of hundreds or thousands of birds sweep across the sky as if a single organism. The birds flying over Rome in particular have captured the imagination of bird enthusiasts, tourists, film makers and scientists alike. How do individual birds know when to turn and which way? Some have suggested it's a random thing, each bird simply flies making sure not to run into a neighbor. Others have suggested that some birds initiate a turn and others follow, creating a diffusion effect. In this new study, the researchers suggest that none of the earlier theories is correct—they've come up with something brand new.
To get a better look at the birds in flight, the researchers recorded flocks flying over Rome with high speed cameras and then took the results into their lab for examination. They found that turns are almost always initiated by just a few birds, but rather than other birds trying to figure out where to turn too, they instead simply copy how sharply their neighbor turns. This allows for the turn message to propagate through the flock at a very fast constant speed—approximately 20 to 40 meters per second, the team calculated. That constant message transfer speed means that each bird in a flock can respond in as little as half a second, without causing the flock to break apart.
Perhaps even more interesting is that when the researchers applied a spin factor for the turns by the birds, they found that applying it to the flock as a whole allowed for use of the same mathematical equations as physicists use to describe superfluid helium. The researchers believe that's not a coincidence, as there are many examples of physics and math principles that apply to the natural world.
By attaching short sequences of single-stranded DNA to nanoscale building blocks, researchers can design structures that can effectively build themselves. The building blocks that are meant to connect have complementary DNA sequences on their surfaces, ensuring only the correct pieces bind together as they jostle into one another while suspended in a test tube.
Now, a University of Pennsylvania team has made a discovery with implications for all such self-assembled structures.
Earlier work assumed that the liquid medium in which these DNA-coated pieces float could be treated as a placid vacuum, but the Penn team has shown that fluid dynamics play a crucial role in the kind and quality of the structures that can be made in this way.
As the DNA-coated pieces rearrange themselves and bind, they create slipstreams into which other pieces can flow. This phenomenon makes some patterns within the structures more likely to form than others.
Ozone and higher temperatures can combine to reduce crop yields, but effects will vary by region.
Many studies have shown the potential for global climate change to cut food supplies. But these studies have, for the most part, ignored the interactions between increasing temperature and air pollution — specifically ozone pollution, which is known to damage crops.
A new study involving researchers at MIT shows that these interactions can be quite significant, suggesting that policymakers need to take both warming and air pollution into account in addressing food security.
The study looked in detail at global production of four leading food crops — rice, wheat, corn, and soy — that account for more than half the calories humans consume worldwide. It predicts that effects will vary considerably from region to region, and that some of the crops are much more strongly affected by one or the other of the factors: For example, wheat is very sensitive to ozone exposure, while corn is much more adversely affected by heat.
The research was carried out by Colette Heald, an associate professor of civil and environmental engineering (CEE) at MIT, former CEE postdoc Amos Tai, and Maria van Martin at Colorado State University. Their work is described this week in the journal Nature Climate Change.
Overall, with all other factors being equal, warming may reduce crop yields globally by about 10 percent by 2050, the study found. But the effects of ozone pollution are more complex — some crops are more strongly affected by it than others — which suggests that pollution-control measures could play a major role in determining outcomes. Ozone pollution can also be tricky to identify, Heald says, because its damage can resemble other plant illnesses, producing flecks on leaves and discoloration.
Potential reductions in crop yields are worrisome: The world is expected to need about 50 percent more food by 2050, the authors say, due to population growth and changing dietary trends in the developing world. So any yield reductions come against a backdrop of an overall need to increase production significantly through improved crop selections and farming methods, as well as expansion of farmland.
Astronomers using NASA's Chandra X-ray Observatory to explore the Perseus Cluster, a swarm of galaxies approximately 250 million light years from Earth, have observed the spectral line that appears not to come from any known type of matter.
Perseus Cluster a collection of galaxies and one of the most massive known objects in the Universe, immersed in an enormous 'atmosphere' of superheated plasma. It is approximately 768 000 light years across. "I couldn't believe my eyes," says Esra Bulbul of the Harvard Center for Astrophysics. "What we found, at first glance, could not be explained by known physics."
"The cluster's atmosphere is full of ions such as Fe XXV, Si XIV, and S XV. Each one produces a 'bump' or 'line' in the x-ray spectrum, which we can map using Chandra. These spectral lines are at well-known x-ray energies."
Yet, in 2012 when Bulbul added together 17 day's worth of Chandra data, a new line popped up where no line should be. "A line appeared at 3.56 keV (kilo-electron volts) which does not correspond to any known atomic transition," she says. "It was a great surprise."
We detected a weak unidentified emission line at E=(3.55-3.57)+/-0.03 keV in a stacked XMM spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. MOS and PN observations independently show the presence of the line at consistent energies.
When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is significantly detected in all three independent MOS spectra and the PN "all others" spectrum. It is also detected in the Chandra spectra of Perseus with the flux consistent with XMM (though it is not seen in Virgo). However, it is very weak and located within 50-110eV of several known faint lines, and so is subject to significant modeling uncertainties. On the origin of this line, we argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate.
Assuming that all dark matter is in sterile neutrinos with m_s=2E=7.1 keV, our detection in the full sample corresponds to a neutrino decay mixing angle sin^2(2theta)=7e-11, below the previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model. This appears to be because of an anomalously bright line at E=3.62 keV in Perseus, possibly an Ar XVII dielectronic recombination line, although its flux would be 30 times the expected value and physically difficult to understand. In principle, such an anomaly might explain our line detection in other subsamples as well, though it would stretch the line energy uncertainties. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by factor 10-20. Confirmation with Chandra and Suzaku, and eventually Astro-H, are required to determine the nature of this new line.
Back in 2012, the Sun erupted with a powerful solar storm that just missed the Earth but was big enough to "knock modern civilization back to the 18th century," NASA said. The extreme space weather that tore through Earth's orbit on July 23, 2012, was the most powerful in 150 years, according to a statement posted on the US space agency website Wednesday.
However, few Earthlings had any idea what was going on. "If the eruption had occurred only one week earlier, Earth would have been in the line of fire," said Daniel Baker, professor of atmospheric and space physics at the University of Colorado. Instead the storm cloud hit the STEREO-A spacecraft, a solar observatory that is "almost ideally equipped to measure the parameters of such an event," NASA said. Scientists have analyzed the treasure trove of data it collected and concluded that it would have been comparable to the largest known space storm in 1859, known as the Carrington event. It also would have been twice as bad as the 1989 solar storm that knocked out power across Quebec, scientists said.
"I have come away from our recent studies more convinced than ever that Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did," said Baker. The National Academy of Sciences has said the economic impact of a storm like the one in 1859 could cost the modern economy more than two trillion dollars and cause damage that might take years to repair. Experts say solar storms can cause widespread power blackouts, disabling everything from radio to GPS communications to water supplies -- most of which rely on electric pumps.
They begin with an explosion on the Sun's surface, known as a solar flare, sending X-rays and extreme UV radiation toward Earth at light speed. Hours later, energetic particles follow and these electrons and protons can electrify satellites and damage their electronics.
Next are the coronal mass ejections, billion-ton clouds of magnetized plasma that take a day or more to cross the Sun-Earth divide. These are often deflected by Earth's magnetic shield, but a direct hit could be devastating.
Highly purified crystals that split light with uncanny precision are key parts of high-powered lenses, specialized optics and, potentially, computers that manipulate light instead of electricity. But producing these crystals by current techniques, such as etching them with a precise beam of electrons, is often extremely difficult and expensive.
Now, researchers at Princeton and Columbia universities have proposed a new method that could allow scientists to customize and grow these specialized materials, known asphotonic crystals, with relative ease.
"Our results point to a previously unexplored path for making defect-free crystals using inexpensive ingredients," said Athanassios Panagiotopoulos, the Susan Dod Brown Professor of Chemical and Biological Engineering and one of the paper's authors. "Current methods for making such systems rely on using difficult-to-synthesize particles with narrowly tailored directional interactions."
Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus.
This graphic shows a 3-D model of 98 geysers whose source locations and tilts were found in a Cassini imaging survey of Enceladus' south polar terrain by the method of triangulation. While some jets are strongly tilted, it is clear the jets on average lie in four distinct "planes" that are normal to the surface at their source location.
Dotted vectors indicate five jets whose sources were determined from images acquired too closely in time to determine tilts accurately. Consequently their 3-D configuration has a large uncertainty associated with it. Two geysers, indicated by crosses in PIA17188, have no tilt determinations at all and are not shown here.
A movie showing a 360-degree view of this model is also presented here. The still graphic and the movie illustrate some of the findings reported in a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014: http://dx.doi.org/10.1088/0004-6256/148/3/46. .
Post-equinox images like this, clearly showing the different projected locations of the intersection between the shadow and the curtain of jets from each fracture, were useful for scientists in checking the triangulated positions of the geysers, as described in a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014: http://dx.doi.org/10.1088/0004-6256/148/3/45.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
Babies can learn what to fear in the first days of life just by smelling the odor of their distressed mothers, new research suggests. And not just "natural" fears: If a mother experienced something before pregnancy that made her fear something specific, her baby will quickly learn to fear it too -- through the odor she gives off when she feels fear.
In the first direct observation of this kind of fear transmission, a team of University of Michigan Medical School and New York University studied mother rats who had learned to fear the smell of peppermint -- and showed how they "taught" this fear to their babies in their first days of life through their alarm odor released during distress.
In a new paper in the Proceedings of the National Academy of Sciences, the team reports how they pinpointed the specific area of the brain where this fear transmission takes root in the earliest days of life.
Their findings in animals may help explain a phenomenon that has puzzled mental health experts for generations: how a mother's traumatic experience can affect her children in profound ways, even when it happened long before they were born.
The researchers also hope their work will lead to better understanding of why not all children of traumatized mothers, or of mothers with major phobias, other anxiety disorders or major depression, experience the same effects.
"During the early days of an infant rat's life, they are immune to learning information about environmental dangers. But if their mother is the source of threat information, we have shown they can learn from her and produce lasting memories," says Jacek Debiec, M.D., Ph.D., the U-M psychiatrist and neuroscientist who led the research.
"Our research demonstrates that infants can learn from maternal expression of fear, very early in life," he adds. "Before they can even make their own experiences, they basically acquire their mothers' experiences. Most importantly, these maternally-transmitted memories are long-lived, whereas other types of infant learning, if not repeated, rapidly perish."
Influenza imposes a heavy annual public health burden, and lies historically at the heart of a number of global pandemics that killed tens of millions. To overcome the challenges of manufacturing enough vaccines such that we may stave off the next epidemic, medical researchers are searching for ways to strengthen or extend the power of existing and stockpiled vaccines. Now a team of scientists in Boston has just developed a new method of using laser light to stimulate and enhance the immune response to a vaccine by a remarkable 4 to 7-fold against disease agents. Such treatments that assist vaccines but are not vaccines themselves are known as adjuvants.
Interestingly, the improved 4 to 7-fold laser adjuvant could not be matched even when compared against increasing the vaccine dosage 10-fold. Efficacy of the vaccine was measured by the level of influenza-specific antibodies generated in an inoculated person. The new method improves on an existing adjuvant hampered by harmful side effects which thus far has prevented its usage broadly. Although the results were obtained in the context of two animal models, adult and aged mice, as well as pigs, its fairly general immunological basis is expected to translate to humans.
Before inoculation, the injection site is exposed to laser light for a short time. The light does not perforate the outer layers of the skin, but rather injures the dermis. Because of the way the laser light is arranged, this creates a number of “microthermal zones.” In each zone, dermal cells that are damaged stimulate inflammation, signaling danger to the immune system, which in turn attracts antigen-presenting cells (APCs) to the damaged area. APCs are cells that occur naturally in the body that bind antigens of harmful disease agents so as to prepare the rest of the immune system to recognize and neutralize the threat.
The damaged area is so small such that that self-healing occurs within 72 hours. The inspiration for the adjuvant comes from a type of skin treatment used in cosmetic dermatology. In the cosmetic context, the laser light is used to stimulate lightly skin with aged appearance. Post-damage, epithelial cells quickly grow to surround the microthermal zone to give rise to more youthful looking skin. The same class of non-ablative lasers were used in this study.
Myorobotics at the Technical University of Munich, takes us on a fascinating journey on how an adorable humanoid robot with muscles, called Roboy, is born in 9 months, and sheds light on the future of robotics, and what kind of future it might bring us. Being fascinated by the complexity and beauty of everything, Rafael Hostettler always had a hard time to choose. That’s why he has an MSc. in Computational Science from ETH Zurich, where he learnt to simulate just about everything on computers, so he didn’t have to make a decision. Now he’s building robots that imitate the building principles of the human musculoskeletal system and travels the world with Roboy. The 3D printed robot boy that plays in a theatre, goes to school and captivates the audience with his fascinating stories.
A second is always a second. Nevertheless, no clocks are so precise that they can measure the exact duration of a second. So even the most precise atomic clocks are 0.000000000000000001 seconds off each second. Over the course of a few billion years that equals one second.
A single second off over the course of a few billion years may sound like a very precise clock -- and in a way it is but scientists from the University of Copenhagen would like a clock that is even more precise.
So now the scientists are suggesting that the atomic clocks around the world be connected by light rays; creating one big network of atomic clocks.
This network would measure time more precisely than ever before.
With more precise clocks come more precise experiments, and with more precise experiments come new technological possibilities. The Global Position System (GPS) for instance, only became possible when a new clock was invented that was so precise that it could measure how long it took for a signal from a GPS transmitter on Earth to reach satellites in space. Similarly, researchers hope that a more precise clock will lead to new scientific possibilities – and solve the debate over whether constants of nature are really constant at all.
It might soon be possible to perform large-scale 3D motion reconstructions of sporting events or other live performances, thanks to new research by scientists at Carnegie Mellon University. The researchers mounted 480 video cameras in a two-story geodesic dome that enabled them to track the motion of events such as a man swinging a baseball bat or confetti being thrown into the air.
This is all done without any little white balls or other markers attached to the subjects, thanks to a technique for estimating visibility of a target point based on motion. The trick was to leverage established techniques for automatically identifying and tracking points based on visual elements – to find distinctive patterns, in other words – and monitor them over time as they cross between different cameras.
Many traditional challenges in reconstructing 3D motion, such as matching across wide baselines and handling occlusion, reduce in significance as the number of unique viewpoints increases. However, to obtain this benefit, a new challenge arises: estimating precisely which cameras observe which points at each instant in time. This new system presents a maximum a posteriori (MAP) estimate of the time-varying visibility of the target points to reconstruct the 3D motion of an event from a large number of cameras. A newly developed algorithm takes, as input, camera poses and image sequences, and outputs the time-varying set of the cameras in which a target patch is visible and its reconstructed trajectory. It models visibility estimation as a MAP estimate by incorporating various cues including photometric consistency, motion consistency, and geometric consistency, in conjunction with a prior that rewards consistent visibilities in proximal cameras. An optimal estimate of visibility is obtained by finding the minimum cut of a capacitated graph over cameras.
The inventors demonstrate that our method estimates visibility with greater accuracy, and increases tracking performance producing longer trajectories, at more locations, and at higher accuracies than methods that ignore visibility or use photometric consistency alone.
Scientists looking at data from the Baryon Oscillation Spectroscopic Survey (BOSS), the largest program in the third Sloan Digital Sky Survey, have measured the expansion rate of the universe 10.8 billion years ago — a time prior to the onset of accelerated expansion caused by dark energy. The measurement is also the most precise measurement of a universal expansion rate ever made, with only 2% uncertainty. The results were announced at a press conference at the APS’s April meeting on Monday, at the same time that the results were posted on the arXiv.
The rate of universal expansion has changed over the course of the universe’s lifetime. It is believed to have gradually slowed down after the Big Bang, but mysteriously began accelerating again about 7 billion years ago. BOSS and other observatories have previously measured expansion rates going back 6 billion years.
To measure astronomical distances, astronomers will occasionally use so-called “standard candles” – these are supernovae with known luminosities. The difference between the known luminosity and the apparent luminosity indicates the supernova’s distance. The BOSS results measure the expansion factor of the universe using a “standard ruler” – a known distance between celestial objects. The expansion rate can be deduced when the known distance between two objects is compared to their apparent distance and each of their redshifts.
The “standard ruler” in this case is the imprint left over from sound waves in the early universe, also known as baryonic acoustic oscillations, or BAOs. These sound waves from the early universe should have created regularly spaced areas of high and low density in regular matter. For example, scientists see an excess of pairs of galaxies separated by about 450 million light-years – the length of the BAO ruler.
The BOSS experiment looked at the distance between quasars and nearby rings of gas. Quasars – galaxies with a supermassive black hole at their centre – are some of the brightest objects in the universe as a result of radiation from tremendous amounts of material falling into the black hole. Because the quasars formed in areas particularly dense with gas and dust, the imprint of the BAO is strong: it appears as a ring of gas roughly 450 million light-years away from the center of the quasar.
Quasars not only provide an imprint of the BAO, they are also some of the most visible objects at such great distances from the earth. Even supernovae or entire galaxies (of the non-quasar variety) are virtually invisible at a distance of 10.8 billion light-years from earth. The BOSS team studied more than 164,000 quasars to make their measurement.
Australian and Taiwanese scientists have discovered a new molecule which puts the science community one step closer to solving one of the barriers to development of cleaner, greener hydrogen fuel-cells as a viable power source for cars.
Scientists say that the newly-discovered "28copper15hydride" puts us on a path to better understanding hydrogen, and potentially even how to get it in and out of a fuel system, and is stored in a manner which is stable and safe – overcoming Hindenburg-type risks.
"28copper15hydride" is certainly not a name that would be developed by a marketing guru, but while it would send many running for an encyclopaedia (or let's face it, Wikipedia), it has some of the world's most accomplished chemists intrigued.
Its discovery was recently featured on the cover of one of the world's most prestigious chemistry journals, and details are being presented today by Australia's Dr Alison Edwards at the 41st International Conference on Coordination Chemistry, Singapore where 1100 chemists have gathered.
The molecule was synthesised by a team led by Prof Chenwei Liu from the National Dong Hwa University in Taiwan, who developed a partial structure model.
The chemical structure determination was completed by the team at the Australian Nuclear Science and Technology Organisation (ANSTO) using KOALA, one of the world's leading crystallography tools.
Most solid material is made of crystalline structures. The crystals are made up of regular arrangements of atoms stacked up like boxes in a tightly packed warehouse. The science of finding this arrangement, and structure of matter at the atomic level, is crystallography. ANSTO is Australia's home of this science.
A new study led by MIT materials scientists reveals the reason why gold nanoparticles can easily slip through cell membranes to deliver drugs directly to target cells. The nanoparticles enter cells by taking advantage of a route normally used in vesicle-vesicle fusion, a crucial process that allows signal transmission between neurons.
In the July 21 issue of Nature Communications, the researchers describe in detail the mechanism by which these nanoparticles are able to fuse with a membrane. The findings suggest possible strategies for designing nanoparticles — made from gold or other materials — that could get into cells even more easily.
“We’ve identified a type of mechanism that might be more prevalent than is currently known,” says Reid Van Lehn, an MIT graduate student in materials science and engineering and one of the paper’s lead authors. “By identifying this pathway for the first time it also suggests not only how to engineer this particular class of nanoparticles, but that this pathway might be active in other systems as well.”
Most nanoparticles enter cells through endocytosis, a process that traps the particles in intracellular compartments, which can damage the cell membrane and cause cell contents to leak out. But in 2008, MIT researchers found that a special class of gold nanoparticles coated with a mix of molecules could enter cells without any disruption.
Last year, they discovered that the particles were somehow fusing with cell membranes and being absorbed into the cells. In their new study, they created detailed atomistic simulations to model how this happens, and performed experiments that confirmed the model’s predictions.
Recognition is graduating from labs to real-world applications. While it is encouraging to see its potential being tapped, it brings forth a fundamental challenge to the vision researcher: scalability. How can we learn a model for any concept that exhaustively covers all its appearance variations, while requiring minimal or no human supervision for compiling the vocabulary of visual variance, gathering the training images and annotations, and learning the models?
In this work, LEVAN developers introduce a fully-automated approach for learning extensive models for a wide range of variations (e.g. actions, interactions, attributes and beyond) within any concept. Their approach leverages vast resources of online books to discover the vocabulary of variance, and intertwines the data collection and modeling steps to alleviate the need for explicit human supervision in training the models. Their approach organizes the visual knowledge about a concept in a convenient and useful way, enabling a variety of applications across vision and NLP. A comprehensive aggregation of online system has been queried by users to learn models for several interesting concepts including, breakfast, Gandhi, beautiful, etc. To date, the LEVAN system has models available for over 50,000 variations within 150 concepts, and has annotated more than 10 million images with bounding boxes.
Vanderbilt University researchers have discovered that engineered probiotic bacteria (“friendly” bacteria like those in yogurt) in the gut produce a therapeutic compound that inhibits weight gain, insulin resistance, and other adverse effects of a high-fat diet in mice.
“Of course it’s hard to speculate from mouse to human,” said senior investigator Sean Davies, Ph.D., assistant professor of Pharmacology. “But essentially, we’ve prevented most of the negative consequences of obesity in mice, even though they’re eating a high-fat diet.”
The findings published in the August issue of the Journal of Clinical Investigation (open access) suggest that it may be possible to manipulate the bacterial residents of the gut — the gut microbiota — to treat obesity and other chronic diseases.
Davies has a long-standing interest in using probiotic bacteria to deliver drugs to the gut in a sustained manner, in order to eliminate the daily drug regimens associated with chronic diseases. In 2007, he received a National Institutes of Health Director’s New Innovator Award to develop and test the idea.
Other studies have demonstrated that the natural gut microbiota plays a role in obesity, diabetes and cardiovascular disease. “The types of bacteria you have in your gut influence your risk for chronic diseases,” Davies said. “We wondered if we could manipulate the gut microbiota in a way that would promote health.”
To start, the team needed a safe bacterial strain that colonizes the human gut. They selected E. coli Nissle 1917, which has been used as a probiotic treatment for diarrhea since its discovery nearly 100 years ago.
They genetically modified the E. coli Nissle strain to produce a lipid compound called N-acyl phosphatidylethanolamine (NAPE)*, which is normally synthesized in the small intestine in response to feeding. NAPE is rapidly converted to NAE, a compound that reduces both food intake and weight gain. Some evidence suggests that NAPE production may be reduced in individuals eating a high-fat diet.
“NAPE seemed like a great compound to try — since it’s something that the host normally produces,” Davies said.
The investigators added the NAPE-producing bacteria to the drinking water of mice eating a high-fat diet for eight weeks. Mice that received the modified bacteria had dramatically lower food intake, body fat, insulin resistance and fatty liver compared to mice receiving control bacteria.
They found that these protective effects persisted for at least four weeks after the NAPE-producing bacteria were removed from the drinking water. And even 12 weeks after the modified bacteria were removed, the treated mice still had much lower body weight and body fat compared to the control mice. Active bacteria no longer persisted after about six weeks.
The parasitoid fly Ormia ochracea has the remarkable ability to locate crickets using audible sound. This ability is, in fact, remarkable as the fly's hearing mechanism spans only 1.5 mm which is 50× smaller than the wavelength of sound emitted by the cricket.
The hearing mechanism is, for all practical purposes, a point in space with no significant interaural time or level differences to draw from.
It has been discovered that evolution has empowered the fly with a hearing mechanism that utilizes multiple vibration modes to amplify interaural time and level differences. A team of scientist engineers now presents a fully integrated, man-made mimic of the Ormia'shearing mechanism capable of replicating the remarkable sound localization ability of the special fly.
A silicon-micromachined prototype is presented which uses multiple piezoelectric sensing ports to simultaneously transduce two orthogonal vibration modes of the sensing structure, thereby enabling simultaneous measurement of sound pressure and pressure gradient.