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News Article | May 12, 2017
Site: www.eurekalert.org

Scientists have discovered a way to solve a problem that has baffled humans for so long it is mentioned in the Bible: achieving the most efficient packing of objects such as grains and pharmaceutical drugs. Lead researcher Dr Mohammad Saadatfar from The Australian National University (ANU) said the knowledge could be vital for building skyscrapers on sand, understanding how grains were stored in silos, or how drugs were packed and delivered to specific targets in the body. "It's crazy - sand is one of the most common building materials in the world and drugs are often packed in the forms of pills, but we really don't understand how assembly of grains or pills behave," said Dr Saadatfar from the ANU Research School of Physics and Engineering. The international team of physicists and mathematicians used high-resolution CT scans to reveal how spherical particles in a disordered arrangement settle and compact themselves into ordered patterns. "Now we believe that we have uncovered the mechanisms underlying the transition from disordered packing of grains to ordered structures," he said. "Whenever spheres - such as soccer balls, ball bearings or atoms - are packed into a space, the most efficient packing is in a very ordered pattern, known as face-centred cubic. "Sodium and chloride atoms in salt crystals are also arranged and ordered that way." When organised that way, the spheres had a minimum of gaps between them, taking up just over 74 per cent of the space, Dr Saadatfar said. "However, when settling quickly, spheres don't naturally form that arrangement, reaching only 64 per cent at best, an arrangement known as random closed packing," he said. The team had previously shown that the 64 per cent packing is not a random arrangement. In fact, spheres tend to form into tightly-held arrangements of tetrahedra self-organised in rings of five. "For a long time, scientists thought that packing spheres more efficiently was impossible to occur naturally and extremely difficult to observe in the lab," Dr Saadatfar said. "That's because it's hard to move to the perfectly ordered structure. It requires breaking the disordered patterns that developed naturally and that are mechanically robust. "You need to add just the right amount of energy for that - too little energy and the packing remains disordered, too much, the crystal will not form either." Dr Saadatfar said the transition to a tighter packing arrangement was mentioned in the Bible. "Luke 6:38 states 'A good measure, pressed down, shaken together and running over, will be poured into your lap. For with the measure you use, it will be measured to you.' It mentions all the experimental protocols that we used in lab - pressing down, shaking, pouring," Dr Saadatfar said. "I'm not sure the authors of the Bible had nailed the mathematical basis of it." The team used the relatively new field of mathematics known as homology to interpret 3D x-ray microscope images and large-scale computer simulations. Dr Saadatfar said for different particle shapes, the mathematics became much more complex. "When you look at footballs or M&Ms we've got a lot of work to do," Dr Saadatfar said. "I'll be keeping my department supplied with M&Ms for the next few years." The paper, titled 'Pore configuration landscape of granular crystallisation', is published in Nature Communications (DOI:10.1038/NCOMMS15082).


News Article | May 12, 2017
Site: phys.org

Lead researcher Dr Mohammad Saadatfar from The Australian National University (ANU) said the knowledge could be vital for building skyscrapers on sand, understanding how grains were stored in silos, or how drugs were packed and delivered to specific targets in the body. "It's crazy - sand is one of the most common building materials in the world and drugs are often packed in the forms of pills, but we really don't understand how assembly of grains or pills behave," said Dr Saadatfar from the ANU Research School of Physics and Engineering. The international team of physicists and mathematicians used high-resolution CT scans to reveal how spherical particles in a disordered arrangement settle and compact themselves into ordered patterns. "Now we believe that we have uncovered the mechanisms underlying the transition from disordered packing of grains to ordered structures," he said. "Whenever spheres - such as soccer balls, ball bearings or atoms - are packed into a space, the most efficient packing is in a very ordered pattern, known as face-centred cubic. "Sodium and chloride atoms in salt crystals are also arranged and ordered that way." When organised that way, the spheres had a minimum of gaps between them, taking up just over 74 per cent of the space, Dr Saadatfar said. "However, when settling quickly, spheres don't naturally form that arrangement, reaching only 64 per cent at best, an arrangement known as random closed packing," he said. The team had previously shown that the 64 per cent packing is not a random arrangement. In fact, spheres tend to form into tightly-held arrangements of tetrahedra self-organised in rings of five. "For a long time, scientists thought that packing spheres more efficiently was impossible to occur naturally and extremely difficult to observe in the lab," Dr Saadatfar said. "That's because it's hard to move to the perfectly ordered structure. It requires breaking the disordered patterns that developed naturally and that are mechanically robust. "You need to add just the right amount of energy for that - too little energy and the packing remains disordered, too much, the crystal will not form either." Dr Saadatfar said the transition to a tighter packing arrangement was mentioned in the Bible. "Luke 6:38 states 'A good measure, pressed down, shaken together and running over, will be poured into your lap. For with the measure you use, it will be measured to you.' It mentions all the experimental protocols that we used in lab - pressing down, shaking, pouring," Dr Saadatfar said. "I'm not sure the authors of the Bible had nailed the mathematical basis of it." The team used the relatively new field of mathematics known as homology to interpret 3-D x-ray microscope images and large-scale computer simulations. Dr Saadatfar said for different particle shapes, the mathematics became much more complex. "When you look at footballs or M&Ms we've got a lot of work to do," Dr Saadatfar said. "I'll be keeping my department supplied with M&Ms for the next few years." More information: M. Saadatfar et al. Pore configuration landscape of granular crystallization, Nature Communications (2017). DOI: 10.1038/ncomms15082


News Article | May 23, 2017
Site: spaceref.com

A team of international astrophysicists led by The Australian National University (ANU) has shown how most of the antimatter in the Milky Way forms. Antimatter is material composed of the antiparticle partners of ordinary matter -- when antimatter meets with matter, they quickly annihilate each other to form a burst of energy in the form of gamma-rays. Scientists have known since the early 1970s that the inner parts of the Milky Way galaxy are a strong source of gamma-rays, indicating the existence of antimatter, but there had been no settled view on where the antimatter came from. ANU researcher Dr. Roland Crocker said the team had shown that the cause was a series of weak supernova explosions over millions of years, each created by the convergence of two white dwarfs which are ultra-compact remnants of stars no larger than two Suns. "Our research provides new insight into a part of the Milky Way where we find some of the oldest stars in our galaxy," said Dr. Crocker from the ANU Research School of Astronomy and Astrophysics. Dr. Crocker said the team had ruled out the supermassive black hole at the centre of the Milky Way and the still-mysterious dark matter as being the sources of the antimatter. He said the antimatter came from a system where two white dwarfs form a binary system and collide with each other. The smaller of the binary stars loses mass to the larger star and ends its life as a helium white dwarf, while the larger star ends as a carbon-oxygen white dwarf. "The binary system is granted one final moment of extreme drama: as the white dwarfs orbit each other, the system loses energy to gravitational waves causing them to spiral closer and closer to each other," Dr. Crocker said. He said once they became too close the carbon-oxygen white dwarf ripped apart the companion star whose helium quickly formed a dense shell covering the bigger star, quickly leading to a thermonuclear supernova that was the source of the antimatter. Reference: "Diffuse Galactic Antimatter from Faint Thermonuclear Supernovae in Old Stellar Populations," Roland M. Crocker et al., 2017 May 22, Nature Astronomy [https://www.nature.com/articles/s41550-017-0135]. Please follow SpaceRef on Twitter and Like us on Facebook.


News Article | May 16, 2017
Site: news.yahoo.com

Calling all citizen scientists: The Australian National University wants you to join the search for supernovae. Brad Tucker from the ANU Research School of Astronomy and Astrophysics says it’s not possible for one team of researchers to check for exploding stars all the time, but if thousands of people are keeping watch, scientists are sure to get quicker and timelier data. “With the power of the people, we can check these images in minutes and get another telescope to follow up,” Tucker said in a news release. Time is of the essence when it comes to hunting for supernovae. University of Washington astrophysicist Melissa Graham, who studies Type Ia supernovae, says that a star can become more than a billion times brighter when it explodes. But that light fades fast. “After two weeks, they are only 30 percent as bright as they were at peak,” she said. Graham says some telescopes may not be as sensitive as others, and may only detect distant and faint supernovae for about a week after the explosion. To join ANU’s quest, visit Zooniverse.org and head to SkyMapper Sighting. The project has more than 450 volunteers so far. Volunteers can compare images taken over time by SkyMapper, an Australian 1.3-meter telescope surveying the southern sky, and report any changes. As a reward, the first person to correctly discover a supernova will get public recognition as a co-discoverer. Like a similar project called Supernova Hunters, SkyMapper Sighting relies on humans to identify supernovae because our eyes and brains are better at recognizing the proper patterns than computer programs are. Tucker and his colleagues hope to measure the acceleration of the universe’s growth by using the exploding stars as markers. He compares supernovae to light bulbs: If you have light bulbs lined up down a road, the one closest to you will look brighter than the one farthest away. “If you know how bright your bulb is, and how bright your bulb should be, you can calculate that difference, and that difference is a distance,” Tucker explained in a video.


News Article | May 25, 2017
Site: www.sciencemag.org

The extent to which rare animal poachers piggyback on scientific research became clear to Mark Auliya soon after he published a 2012 paper announcing the discovery of the Borneo earless monitor lizard (Lanthanotus borneensis) in a new part of the southeast Asian island. The conservation biologist at the Helmholtz Centre for Environmental Research in Leipzig, Germany, had left the lizards’ location vague, in an attempt to shield the animal from collectors and their suppliers. Nevertheless, within a year, the lizard was turning up outside Borneo. So Auliya embraces a new call, published today in Science, for scientists to keep mum about details that could turn rare and sought-after species into the next easy target for the global wild animal trade. “It’s terrible,” he says. “If you describe a new species in the Democratic Republic of Congo, you should probably only list the country.” In today’s Perspective, two Australian conservation biologists urge scientists to adopt a policy of strategic “self-censorship” to shield the animals and plants they study. For species that are likely targets for collectors, they urge scientists to share detailed information about where the species is found only with government agencies, while hiding it from the public. Such secrecy runs counter to the imperative to share research with the scientific world, and the push to make it quickly and widely available. But that openness is taking a devastating toll, says David Lindenmayer, the article’s lead author and a conservation biologist at The Australian National University in Canberra.  “For some of the really important species, if we don’t do something they’re going to get wiped off the map.” He was alerted to the intensity of the problem in 2016, when he got a call from a landowner about people tearing apart rocky outcrops with crowbars. Lindenmayer figured out that the interlopers were on the hunt for the rare pink-tailed worm-lizard (Aprasia parapulchella), a bizarre legless gecko that grows to 15 centimeters, spends its life in rocky fissures in Australia, feeds on ants, and squeaks when picked up. The animal’s location at the farm was first reported just weeks earlier, from information the government requires Lindenmayer to provide in an open-access online database. Since then, he has gathered accounts from fellow scientists about a host of species targeted for poaching shortly after their discovery was published. He fears that this pressure has only increased as new scientific research becomes available to the world with the click of a mouse. “The era of online data, of open-access data, data in real time, all those kinds of things, opens up a whole new set of opportunities for people who want to poach animals,” he says. This entanglement of science and poaching isn’t new, says Mark Burgman, a conservation biologist at Imperial College London, and editor-in-chief of the journal Conservation Biology. Neither is the use of scientific subterfuge to foil thieves. The pressure is acute for rare or unusual species sought by collectors: amphibians, orchids, birds, and reptiles—particularly venomous snakes. One paper he published about the discovery of a plant included a map that had been manipulated to make the location indiscernible. He worked with the journal to create the altered map. In Australia in the 1980s, he managed a database for state government that listed the locations of certain species only down to within roughly a hundred kilometers, to make them harder to find. Burgman says secrecy should be handled on a case-by-case basis between scientists and sources of scientific information, such as journals. Any secret information can be revealed to other scientists or government officials on a need-to-know basis. But there are drawbacks to shielding new data, says Bryan Stuart, a herpetologist at the North Carolina Museum of Natural Sciences in Raleigh. Information about a species’ location can be crucial to guiding conservation efforts. And such information can still leak out through avenues such as museum collections, he says. “I believe that withholding locality data is only a temporary measure,” he wrote in an email. Stuart co-wrote a 2006 letter in Science urging scientists to try to address the poaching problem by working closely with conservation managers to have protections for the species in place when the research is published. He acknowledges, however, that this approach won’t always succeed. Auliya, meanwhile, hopes the new attention might revive his attempt to host a workshop where scientists can hash out guidelines for how to publish their findings without imperiling the very species they are studying. In 2012 he tried to arrange such a gathering, but couldn’t get it funded.


Online volunteers, including a woman from Belgium and a Scottish man, have helped astronomers at The Australian National University (ANU) find a star that exploded 970 million years ago, predating the dinosaurs' time on Earth. ANU has invited everyone with an interest in astronomy to join the University's search for exploding stars called supernovae, which scientists can use to measure the Universe and acceleration of its growth. Co-lead researcher Dr Brad Tucker said his team was able to confirm a previously unknown object was a real exploding star in just a day, thanks to the efficiency and dedication of volunteer supernovae hunters - more than 700 of them. "The supernova is about 970 million light years away, meaning that it exploded before the dinosaurs were even on the Earth," said Dr Tucker from the ANU Research School of Astronomy and Astrophysics (RSAA). "This is the exact type of supernova we're looking for - type Ia supernova - to measure properties of and distances across the Universe." Among the amateur co-discoverers are Alan Craggs from Aberdeenshire in Scotland and Elisabeth Baeten from Belgium. Seven potential supernovae have been reported to the Transient Name Server. "We are tracking 18 other possible exploding stars," Dr Tucker said. Co-lead researcher Dr Anais Möller said the Ia supernova discovered through the ANU project had already been named. "Supernovae have boring names - it's called SN2017dxh," said Dr Möller from RSAA. "We are recognising volunteers by listing the first three people to find a previously unknown supernova in the discovery when we report it to the International Astronomical Union. "In the first 24 hours we had over 30,000 classifications. We've almost reached 40,000 classifications, with more than 1,300 images classified, since the launch of our project." Astrophysicists use supernovae, which are explosions as bright as 100 million billion billion billion lightning bolts, as light sources to measure how the Universe is growing and better understand dark energy, the cause of the Universe's acceleration. Scientists can measure the distance of a supernova from Earth by calculating how much the light from the exploding star fades. The ANU project allows citizen scientists to use a web portal on Zooniverse.org to search images taken by the SkyMapper 1.3-metre telescope at the ANU Siding Spring Observatory for the SkyMapper Transient Survey. Citizen volunteers scan the SkyMapper images online to look for differences and mark up those differences for the researchers to follow up. SkyMapper is the only telescope that is doing a comprehensive survey of the southern sky looking for supernovae and other interesting transient events at these distances. Watch a video interview with Dr Brad Tucker about the project: youtu.be/NzSG9Ax_e_s People can to participate in the ANU citizen science project at http://www. to join the search for exploding stars.


Astronomy amateurs have helped Australian scientists find a star that exploded around 970 million years ago – long before the dinosaurs even roamed the Earth. Such exploding stars are known as supernovae. Although they burn only for a short amount of time, they can tell astronomers a lot about the universe. For instance, one type of supernova has allowed them to determine that the universe is expanding at an ever increasing rate. Supernovae are explosions as bright as 100 million billion billion billion lightning bolts, and scientists now use them as light source to measure this growth of the universe. These stars have also been shown to play a key role in the distribution of the elements throughout the universe. When the star explodes, it shoots elements and debris into space and go on to form new stars, planets and everything else in the universe. The newly identified supernova has been named SN2017dxh. Its discovery was made possible thanks to an innovative strategy adopted by the scientists from The Australian National University (ANU). They invited members of the public to join their search for supernovae, asking them them to log on a dedicated web portal and to examine images taken by the SkyMapper 1.3-metre telescope at the ANU Siding Spring Observatory for the SkyMapper Transient Survey. The 700 volunteers who responded to the scientists' call scanned the SkyMapper images online, comparing pictures from the same area of the sky taken at different points in time. They marked up any differences for the researchers to follow up. In just a day, the team was able to confirm that a previously unknown object was a real exploding star. "The supernova is about 970 million light years away, meaning that it exploded before the dinosaurs were even on the Earth," said Dr Tucker from the ANU Research School of Astronomy and Astrophysics (RSAA). "This is the exact type of supernova we're looking for - type Ia supernova - to measure properties of and distances across the Universe." He added that they were currently tracking 18 other possible similar exploding stars. You may be interested in:


Online volunteers, including a woman from Belgium and a Scottish man, have helped astronomers at The Australian National University (ANU) find a star that exploded 970 million years ago, predating the dinosaurs' time on Earth. ANU has invited everyone with an interest in astronomy to join the University's search for exploding stars called supernovae, which scientists can use to measure the Universe and acceleration of its growth. Co-lead researcher Dr Brad Tucker said his team was able to confirm a previously unknown object was a real exploding star in just a day, thanks to the efficiency and dedication of volunteer supernovae hunters -- more than 700 of them. "The supernova is about 970 million light years away, meaning that it exploded before the dinosaurs were even on the Earth," said Dr Tucker from the ANU Research School of Astronomy and Astrophysics (RSAA). "This is the exact type of supernova we're looking for -- type Ia supernova -- to measure properties of and distances across the Universe." Among the amateur co-discoverers are Alan Craggs from Aberdeenshire in Scotland and Elisabeth Baeten from Belgium. Seven potential supernovae have been reported to the Transient Name Server. "We are tracking 18 other possible exploding stars," Dr Tucker said. Co-lead researcher Dr Anais Möller said the Ia supernova discovered through the ANU project had already been named. "Supernovae have boring names -- it's called SN2017dxh," said Dr Möller from RSAA. "We are recognising volunteers by listing the first three people to find a previously unknown supernova in the discovery when we report it to the International Astronomical Union. "In the first 24 hours we had over 30,000 classifications. We've almost reached 40,000 classifications, with more than 1,300 images classified, since the launch of our project." Astrophysicists use supernovae, which are explosions as bright as 100 million billion billion billion lightning bolts, as light sources to measure how the Universe is growing and better understand dark energy, the cause of the Universe's acceleration. Scientists can measure the distance of a supernova from Earth by calculating how much the light from the exploding star fades. The ANU project allows citizen scientists to use a web portal on Zooniverse.org to search images taken by the SkyMapper 1.3-metre telescope at the ANU Siding Spring Observatory for the SkyMapper Transient Survey. Citizen volunteers scan the SkyMapper images online to look for differences and mark up those differences for the researchers to follow up. SkyMapper is the only telescope that is doing a comprehensive survey of the southern sky looking for supernovae and other interesting transient events at these distances.


News Article | May 3, 2017
Site: www.eurekalert.org

A study led by The Australian National University (ANU) has solved the 168-year-old mystery of how the world's biggest and most active volcanoes formed in Hawaii. The study found that the volcanoes formed along twin tracks due to a shift in the Pacific Plate's direction three million years ago. Lead researcher Tim Jones from ANU said scientists had known of the existence of the twin volcanic tracks since 1849, but the cause of them had remained a mystery until now. "The discovery helps to better reconstruct Earth's history and understand part of the world that has captivated people's imagination," said Mr Jones, a PhD student from the ANU Research School of Earth Sciences (RSES). "The analysis we did on past Pacific Plate motions is the first to reveal that there was a substantial change in motion 3 million years ago. It helps to explain the origin of Hawaii, Earth's biggest volcanic hotspot and one of the most popular tourist destinations in the world." Twin volcanic tracks exist in other parts of the Pacific, including Samoa, and the study found that these also emerged three million years ago. Mr Jones said this kind of volcanic activity was surprising because it occurred away from tectonic plate boundaries, where most volcanoes are found. "Heat from the Earth's core causes hot columns of rock, called mantle plumes, to rise under tectonic plates and produce volcanic activity on the surface," he said. "Mantle plumes have played a role in mass extinctions, the creation of diamonds and the breaking up of continents." Co-researcher Dr Rhodri Davies from RSES said the twin volcanic tracks emerged because the mantle plume was out of alignment with the direction of the plate motion. "Our hypothesis predicts that the plate and the plume will realign again at some stage in the future, and the two tracks will merge to form a single track once again," Dr Davies said. "Plate shifts have been occurring constantly, but irregularly, throughout Earth's history. Looking further back in time we find that double tracks are not unique to young Hawaiian volcanism - indeed, they coincide with other past changes in plate motion." Hawaii sits at the south-eastern limit of a chain of volcanoes and submerged seamounts which get progressively older towards the north west. The researchers worked with the National Computational Infrastructure at ANU to model the Pacific Plate's change in direction and formation of the twin volcanic tracks through Hawaii. The study is published in Nature. For media assistance, contact Will Wright from the ANU Media Team on +612 6125 7979, +61 478 337 740 or media@anu.edu.au


Casagrande L.,The Australian National University | VandenBerg D.A.,University of Victoria
Monthly Notices of the Royal Astronomical Society | Year: 2014

After a pedagogical introduction to the main concepts of synthetic photometry, colours and bolometric corrections in the Johnson-Cousins, 2MASS, and HST-ACS/WFC3 photometric systems are generated from MARCS synthetic fluxes for various [Fe/H] and [α/Fe] combinations, and virtually any value of E(B - V) ≤ 0.7. The successes and failures of model fluxes in reproducing the observed magnitudes are highlighted. Overall, extant synthetic fluxes predict quite realistic broad-band colours and bolometric corrections, especially at optical and longer wavelengths: further improvements of the predictions for the blue and ultraviolet spectral regions await the use of hydrodynamic models where the microturbulent velocity is not treated as a free parameter. We show how the morphology of the colour-magnitude diagram (CMD) changes for different values of [Fe/H] and [α/Fe]; in particular, how suitable colour combinations can easily discriminate between red giant branch and lower main-sequence populations with different [α/Fe], due to the concomitant loops and swings in the CMD. We also provide computer programs to produce tables of synthetic bolometric corrections as well as routines to interpolate in them. These colour-Teff-metallicity relations may be used to convert isochrones for different chemical compositions to various bandpasses assuming observed reddening values, thus bypassing the standard assumption of a constant colour excess for stars of different spectral type. We also show how such an assumption can lead to significant systematic errors. The MARCS transformations presented in this study promise to provide important constraints on our understanding of the multiple stellar populations found in globular clusters (e.g. the colours of lower main-sequence stars are predicted to depend strongly on [α/Fe]) and of those located towards/in the Galactic bulge. © 2014 The Authors.

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