The research found the females are actually searching for a safe haven from birds and other predators rather than hunting for the perfect match. Researcher Professor Patricia Backwell from The Australian National University (ANU) said the findings overturn previous theories and helped scientists better understand the breeding habits of fiddler crabs, which are crucial to the ecological health of mangroves, salt marshes and muddy beaches around the world. "This behaviour of visiting and supposedly rejecting successive males has always been taken as a defining feature of female choosiness, but this study shows that things are not always what they seem," said Professor Backwell, from the ANU Research School of Biology. Male fiddler crabs are known for having one claw that is considerably larger than the other. Fiddler crabs are found in mangroves and salt marshes and on sandy or muddy beaches of West Africa, the Western Atlantic, Eastern Pacific and Indo-Pacific. Professor Backwell said female fiddler crabs visited successive displaying males in their burrows to identify safe places to hide in the event of predator attacks, and not because they were searching for a perfect mating partner. "If a bird attacks, female fiddler crabs can move quickly and directly back to the last burrow it visited," said Professor Backwell, who is based in Darwin at the moment to conduct field work. "Having this map of burrow positions is essential if they are to survive a bird attack, and this is true for females who are looking for a mate and those who are looking for a burrow." Co-lead researcher Dr Marianne Peso said the team conducted experiments to observe and compare the behaviour of mate- and burrow-searching females. The team noticed female fiddler crabs not seeking a mate visited successive males before settling in a new burrow in the same manner as mate-searching females. "We watched displaced females move across the mudflat, testing mate preferences with male-mimicking robotic crabs, examining male reactions to the females and testing the females' response to a simulated bird predator," said Dr Peso, who was based at ANU at the time of the study and is now at Macquarie University Department of Biological Sciences. "In all experiments, mate-searching and burrow-searching females behaved identically. "They all visited courting males, they found the same robotic males attractive, males treated them in the same way as potential mates and all the females retreated to the last burrow they visited when swooped by the plastic bird." More information: M. Peso et al, Not what it looks like: mate-searching behaviour, mate preferences and clutch production in wandering and territory-holding female fiddler crabs: Table 1., Royal Society Open Science (2016). DOI: 10.1098/rsos.160339
Lead researcher Dr Yuerui (Larry) Lu from The Australian National University (ANU) said the discovery hinged on the remarkable potential of the molybdenum disulphide crystal. "This type of material is the perfect candidate for future flexible displays," said Dr Lu, leader of Nano-Electro-Mechanical System (NEMS) Laboratory in the ANU Research School of Engineering. "We will also be able to use arrays of micro lenses to mimic the compound eyes of insects." The 6.3-nanometre lens outshines previous ultra-thin flat lenses, made from 50-nanometre thick gold nano-bar arrays, known as a metamaterial. "Molybdenum disulphide is an amazing crystal," said Dr Lu "It survives at high temperatures, is a lubricant, a good semiconductor and can emit photons too. "The capability of manipulating the flow of light in atomic scale opens an exciting avenue towards unprecedented miniaturisation of optical components and the integration of advanced optical functionalities." Molybdenum disulphide is in a class of materials known as chalcogenide glasses that have flexible electronic characteristics that have made them popular for high-technology components. Dr Lu's team created their lens from a crystal 6.3-nanometres thick - 9 atomic layers - which they had peeled off a larger piece of molybdenum disulphide with sticky tape. They then created a 10-micron radius lens, using a focussed ion beam to shave off the layers atom by atom, until they had the dome shape of the lens. The team discovered that single layers of molybdenum disulphide, 0.7 nanometres thick, had remarkable optical properties, appearing to a light beam to be 50 times thicker, at 38 nanometres. This property, known as optical path length, determines the phase of the light and governs interference and diffraction of light as it propagates. "At the beginning we couldn't imagine why molybdenum disulphide had such surprising properties," said Dr Lu. Collaborator Assistant Professor Zongfu Yu at the University of Wisconsin, Madison, developed a simulation and showed that light was bouncing back and forth many times inside the high refractive index crystal layers before passing through. Molybdenum disulphide crystal's refractive index, the property that quantifies the strength of a material's effect on light, has a high value of 5.5. For comparison, diamond, whose high refractive index causes its sparkle, is only 2.4, and water's refractive index is 1.3. This study is published in the Nature serial journal Light: Science and Applications. Explore further: New material allows for ultra-thin solar cells
News Article | September 7, 2016
The Australian National University will establish an international research program to improve ways to store renewable energy under a new $8 million partnership with the ACT Government. ANU Vice-Chancellor Professor Brian Schmidt thanked the ACT Government for contributing up to $5 million to support the program, which would help to establish Australian research leadership in the integration of battery material technology with electricity network storage.
News Article | January 18, 2015
It was an interesting week for ideas about the future of the Internet. On Wednesday, satellite industry notable Greg Wyler announced that his company OneWeb, which wants to build a micro-satellite network to bring Internet to all corners of the globe, secured investments from Richard Branson's Virgin Group and Qualcomm. Then in a separate announcement on Friday, Elon Musk said that he would also be devoting his new Seattle office to creating "advanced micro-satellites" to deliver Internet. OneWeb, formerly WorldVu Satellites Ltd, aims to target rural markets, emerging markets, and in-flight Internet services on airlines, the Wall Street Journal reported. Both Branson and Qualcomm Executive Chairman Paul Jacobs will sit on the company's board, but Wyler did not say how much Virgin and Qualcomm invested in his company. WSJ: Plan to "deliver Internet access across the globe" in early stages. Wyler said that his company's goal is to create a network of 648 small satellites that would weigh in at around 285 pounds each. The satellites would be put in orbit 750 miles above the Earth and ideally cost about $350,000 each to build using an assembly line approach. Wyler also said that Virgin, which has its own space segment, would be launching the satellites into orbit. “As an airline and mobile operator, Virgin might also be a candidate to resell OneWeb’s service,” the Journal noted. Wyler has said that he projects it to take $1.5 billion to $2 billion to launch the service, and he plans to launch in 2018. OneWeb's advantage is that it already secured the rights to a block of radio spectrum that it will use for Internet service through the International Telecommunications Union. Wyler's first big satellite Internet startup was O3b Networks Ltd., which partnered with Google to produce a similar product. That company took six years to launch its service and eventually suffered from satellite performance issues. Wyler left that company in September 2014 to create WorldVu/OneWeb, however, and he took with him the band of spectrum that his new company hopes to use. Bloomberg Businessweek reports that Wyler has a team of more than 30 engineers “developing the satellites, antennas, and software for OneWeb.” On the other hand there's Musk, who's a seasoned space-business launcher that's starting fresh in the world of satellite Internet services. The Telsa and SpaceX founder announced his plans to launch 700 satellites weighing less than 250 pounds each in November. His satellites would also orbit the Earth at 750 miles above. Musk spoke to Bloomberg on Friday evening explaining that 750 miles above the Earth is much closer than the tens of thousands of miles above the Earth at which traditional telecommunications satellites operate. “The speed of light is 40 percent faster in the vacuum of space than it is for fiber,” Musk said. “The long-term potential is to be the primary means of long-distance Internet traffic and to serve people in sparsely populated areas.” In Musk's vision, while sending data from Los Angeles to San Francisco may not be faster by satellite, sending data from Johannesburg to San Francisco might. Musk said on Friday night that the project would be based out of the Seattle office, and he will start with a team of 60 that could expand into a team of 1,000 in three to four years. “The employees will also work on SpaceX’s Falcon rockets, Dragon capsules, and additional vehicles to carry various supplies (and soon, people) into space,” Bloomberg reports. Musk's venture will be considerably more expensive, possibly costing as much at $10 billion. It could take more than five years to get operational. “But we see it as a long-term revenue source for SpaceX to be able to fund a city on Mars,” Musk said on Friday night. “It will be important for Mars to have a global communications network as well. I think this needs to be done, and I don’t see anyone else doing it.” Of course, satellite Internet as it now stands can't touch the quality of terrestrial-bound Internet in most areas of the world. And the Wall Street Journal notes that, “Historically, complex satellite projects with large constellations have run over budget and taken longer than expected to build and deploy.” In November when Musk first put forward the idea of creating a satellite network for Internet services, anonymous sources indicated that Wyler and Musk were considering working together to bring down the cost and the risks of such a difficult venture. On Friday, however, Musk made it clear that the two companies are competitors more than partners, asserting that SpaceX’s manufacturing techniques would give the company an edge over OneWeb. “Greg and I have a fundamental disagreement about the architecture,” Musk said on Friday. “We want a satellite that is an order of magnitude more sophisticated than what Greg wants. I think there should be two competing systems.” Branson, for his part, told Bloomberg that Musk doesn't have a chance compared to Wyler. “Greg has the rights, and there isn’t space for another network—like there physically is not enough space. If Elon wants to get into this area, the logical thing for him would be to tie up with us, and if I were a betting man, I would say the chances of us working together rather than separately would be much higher.”
Human remains, estimated to be about 2,500 years old, were unearthed at the Plain of Jars site in Laos. An ancient burial site, including an oddly shaped quartz stone covering the face of one of the newly uncovered human skeletons, has been discovered at the mysterious Plain of Jars, an archaeological site in remote central Laos littered with thousands of stone vessels. The new findings could help researchers solve the long-standing puzzle of why the stone jars were scattered across this part of Laos. When it was found, the skull beneath the quartz adornment appeared to be looking through a large hole in the stone, said Dougald O’Reilly, an archaeologist at the Australian National University (ANU), who led a team of scientists on a joint Laos-Australian expedition to the Plain of Jars in February. [In Photos: Exploring the Mysterious Plain of Jars Site] "When we excavated it, the skull was actually looking out through that perforation. It was quite interesting, but whether it was done purposefully is difficult to know," O’Reilly told Live Science. The burial site is estimated to be 2,500 years old, and was found when researchers from ANU, Monash University in Australia and the Laos Ministry of Information, Culture, and Tourism, spent four weeks mapping and excavating the ground around a group of the massive carved stone jars that dot the landscape. More than 90 jar sites — some with up to 400 stone jars measuring as tall as 10 feet (3 meters) high — are spread across foothills, forests and upland valleys of this remote region. The members of the Laos-Australian expedition worked at the most accessible site, known as Jar Site 1, located a few miles outside the city of Phonsavan, in Xiangkhoang province in central Laos. The researchers plan to explore a second, more remote jar site next year. The Laos government hopes to develop Jar Site 1 as an archaeological center and UNESCO World Heritage site, to protect the unique Plain of Jars landscape and to stimulate scholarship and cultural tourism in the area. O’Reilly said the latest expedition was the first major effort by archaeologists since the 1930s to visit the site, in an effort to understand the purpose of the jars and who created them. Since that time, however, some archaeologists have undertaken important work at the Plain of Jars, mainly on their own. [The 7 Most Mysterious Archaeological Finds on Earth] The latest team of around 11 researchers worked together to compile the first comprehensive scientific study of one of the jar sites, including a GIS (geographic information system) map recording the precise location of each of the jars, stone disks and quartz stone markers scattered over the site. The largest jars weigh more than 10 tons (9,000 kilograms), and a big part of their mystery is how they got there. "There are a few well-known quarry sites where the jars were sourced and then brought across the landscape, about 8 to 10 kilometers [5 to 6 miles] to the jar sites," O'Reilly said. "So there's a huge amount of effort involved in moving them — one would have to speculate that elephants must have been involved, given the incredible weight of the jars." And carving the massive jars would have been no easy task for primitive peoples with iron tools, he added. "Some of the jars are over 2 meters [6.5 feet] or perhaps even 3 meters [10 feet] in height, and in girth you couldn't get your arms around most of them," O'Reilly said. "And there are variations in the design of the jars: some have larger or smaller openings, some are rectangular, some circular or oval — in some cases you wonder how did they even carve these things?" The variety of sizes and shapes of the jars has prompted many researchers to theorize about their purpose over the years. "It’s probably likely that they do represent a memorial of some kind, and the variations in the sizes of the jars may indicate that there were differences in status and perhaps a hierarchy in the society that created the jars," O'Reilly said. "You could spend a lot of time theorizing." The burial site with the oddly shaped quartz stone was one of three distinct types of burial sites found at Jar Site 1, the researchers said. [Top 10 Weird Ways We Deal With the Dead] "This is the first time that this type of interment has been uncovered at the Plain of Jars, but if there is one, there will probably be others," O'Reilly said. "And this burial is also quite interesting because it contained the remains of not one but two individuals: the cranial bones of what's estimated to be an 8-year-old child were found in that burial as well [as an adult skeleton]." The expedition also uncovered 11 ceramic jars, which are expected to contain "secondary" burials of human bones from which the flesh was removed. A pit filled with bones from several secondary burials and covered with a large limestone block was also found, and the marker stones and stone disks on the ground around the stone jars seemed to correspond to the location of secondary burials, O'Reilly said. Scientific study of samples and remains from the Plain of Jars site will continue in the laboratory. O’Reilly said the expedition recovered some human teeth that could provide DNA for testing and clues to the origins of the ancient peoples buried there. But, DNA tends to degrade heavily in the climate conditions of Southeast Asia, so a proper analysis might not be possible, he added. The contents of the ceramic jars excavated from the site will also be carefully examined to confirm if, as the researchers suspect, they hold human remains. But the Plain of Jars is not giving up all its secrets just yet. Although some archaeologists have proposed that the stone jars were used to decompose bodies before the bones were cleaned for secondary burials, it may be impossible to know for sure. "This is something you find in various religious practices in different parts of the world, but it's something that needs to be investigated a little further at the Plain of Jars," O’Reilly said. One of the biggest problems at the site is that the jars have been exposed to the harsh Southeast Asian climate for more than 2,000 years, making it very difficult for scientists to study and run test on the artifacts. "Possibly we could look at trying to extract lipids from the stone jars to see if there is any evidence for decomposition of human remains, but the jars have been exposed for so long that it's a bit of a long shot," he said. "So, I fear we probably will never know the true purpose of the large stone jars." 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