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  • richardmitnick 11:10 am on December 22, 2017 Permalink | Reply
    Tags: , , , U Oxford, Where Did All That Mars Water Go? Scientists Have a New Idea   

    From U Oxford via Science Alert: “Where Did All That Mars Water Go? Scientists Have a New Idea” 

    U Oxford bloc

    Oxford University

    Science Alert

    21 DEC 2017
    DAVID NIELD

    1
    (Earth Observatory of Singapore/James Moore/Jon Wade)

    It’s still there… kind of.

    Billions of years ago, scientists think Mars was much warmer and wetter than it is now, so where did all that water go? New research published in Nature suggests much of it is actually locked inside the Martian rocks, which have soaked up the liquid water like a giant sponge.

    That teases an interesting addition to the commonly held hypothesis that the planet dried out as its atmosphere was stripped away by solar winds.

    Using computer modelling techniques and data we’ve collected on rocks here on Earth, the international team of scientists reckon that basalt rocks on Mars can hold up to 25 percent more water than the equivalent rocks on our own planet, and that could help explain where all the water disappeared to.

    “People have thought about this question for a long time, but never tested the theory of the water being absorbed as a result of simple rock reactions,” says lead researcher Jon Wade from the University of Oxford in the UK.

    Thanks to differences in temperature, pressure, and the chemical make-up of the rocks themselves, water on Mars could’ve been sucked up by the rocky surface while Earth kept its lakes and oceans, the researchers say.

    Martian rocks can also hold water down to a greater depth than the rocks on Earth can, according to the simulations.

    “The Earth’s current system of plate tectonics prevents drastic changes in surface water levels, with wet rocks efficiently dehydrating before they enter the Earth’s relatively dry mantle,” explains Wade.

    In the early days of the Earth and Mars, however, this wouldn’t have been the case, the researchers suggest. Volcanic lava layers would have changed the make-up of the rocks at the surface and could have made them more absorbent.

    “On Mars, water reacting with the freshly erupted lavas that form its basaltic crust, resulted in a sponge-like effect,” says Wade. “The planet’s water then reacted with the rocks to form a variety of water-bearing minerals.

    “This water-rock reaction changed the rock mineralogy and caused the planetary surface to dry and become inhospitable to life.”

    Even small differences in the iron content of the rocks on Earth and Mars, for example, can add up to significant changes in the way water gets sucked up, the research says. Plus, Mars is a much smaller planet, which would also have been a factor.

    The team agrees that solar winds are likely to have stripped away some of the water on Mars, but argues that much more of it could be locked away inside the Red Planet than previously thought – very handy once we get to set up base there.

    Experts also think Mars is hiding big reserves of water in the form of underground ice. But until we can take more readings and samples from the surface, it’s all just educated guesswork for the time being.

    Now the researchers want to use the same principles to study the possibility of finding water locked away in other planets, based on the composition of their rocks and tectonic activity – and where there’s water, there might be life.

    “When looking for life on other planets it is not just about having the right bulk chemistry, but also very subtle things like the way the planet is put together, which may have big effects on whether water stays on the surface,” says Wade.

    “These effects and their implications for other planets have not really been explored.”

    See the full article here.

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

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  • richardmitnick 5:10 pm on November 13, 2017 Permalink | Reply
    Tags: Elusive Atomic Deformations, , , Matter in Extreme Condition (MEC) experimental station at SLAC’s LCLS, , SLAC X-ray Laser Reveals How Extreme Shocks Deform a Metal’s Atomic Structure, The Tremendous Shock of a Tiny Recoil, U Oxford, , When hit by a powerful shock wave materials can change their shape – a property known as plasticity – yet keep their lattice-like atomic structure   

    From SLAC: “SLAC X-ray Laser Reveals How Extreme Shocks Deform a Metal’s Atomic Structure” 


    SLAC Lab

    November 13, 2017
    Glennda Chui

    1
    This image depicts an experimental setup at SLAC’s Linac Coherent Light Source, where a tantalum sample is shocked by a laser and probed by an X-ray beam. The resulting diffraction patterns, collected by an array of detectors, show the material undergoes a particular type of plastic deformation called twinning. The background illustration shows a lattice structure that has created twins. (Ryan Chen/LLNL)

    SLAC/LCLS

    When hit by a powerful shock wave, materials can change their shape – a property known as plasticity – yet keep their lattice-like atomic structure. Now scientists have used the X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory to see, for the first time, how a material’s atomic structure deforms when shocked by pressures nearly as extreme as the ones at the center of the Earth.

    The researchers said this new way of watching plastic deformation as it happens can help study a wide range of phenomena, such as meteor impacts, the effects of bullets and other penetrating projectiles and high-performance ceramics used in armor, as well as how to protect spacecraft from high-speed dust impacts and even how dust clouds form between the stars.

    The experiments took place at the Matter in Extreme Condition (MEC) experimental station at SLAC’s Linac Coherent Light Source (LCLS). They were led by Chris Wehrenberg, a physicist at the DOE’s Lawrence Livermore National Laboratory, and described in a recent paper in Nature.

    “People have been creating these really high-pressure states for decades, but what they didn’t know until MEC came online is exactly how these high pressures change materials – what drives the change and how the material deforms,” said SLAC staff scientist Bob Nagler, a co-author of the report.

    “LCLS is so powerful, with so many X-rays in such a short time, that it can interrogate how the material is changing while it is changing. The material changes in just one-tenth of a billionth of a second, and LCLS can deliver enough X-rays to capture information about those changes in a much shorter time that that.”

    Elusive Atomic Deformations

    The material they studied here was a thin foil made of tantalum, a blue-gray metallic element whose atoms are arranged in cubes. The team used a polycrystalline form of tantalum that is naturally textured so the orientation of these cubes varies little from place to place, making it easier to see certain types of disruptions from the shock.

    When this type of crystalline material is squeezed by a powerful shock, it can deform in two distinct ways: twinning, where small regions develop lattice structures that are the mirror images of the ones in surrounding areas, and slip deformation, where a section of the lattice shifts and the displacement spreads, like a propagating crack.

    But while these two mechanisms are fundamentally important in plasticity, it’s hard to observe them as a shock is happening. Previous research had studied shocked materials after the fact, as the material recovered, which introduced complications and led to conflicting interpretations.

    The Tremendous Shock of a Tiny Recoil

    In this experiment, the scientists shocked a piece of tantalum foil with a pulse from an optical laser. This vaporizes a small piece of the foil into a hot plasma that flies away from the surface. The recoil from this tiny plume creates tremendous pressures in the remaining foil – up to 300 gigapascals, which is three million times the atmospheric pressure around us and comparable to the 350-gigapascal pressure at the center of the Earth, Nagler said.

    While this was happening, researchers probed the state of the metal with X-ray laser pulses. The pulses are extremely short – only 50 femtoseconds, or millionths of a billionth of a second, long – and like a camera with a very fast shutter speed they can record the metal’s response in great detail.

    The X-rays bounce off the metal’s atoms and into a detector, where they create a “diffraction pattern” – a series of bright, concentric rings – that scientists analyze to determine the atomic structure of the sample. X-ray diffraction has been used for decades to discover the structures of materials, biomolecules and other samples and to observe how those structures change, but it’s only recently been used to study plasticity in shock-compressed materials, Wehrenberg said.

    And this time the researchers took the technique one step further: They analyzed not just the diffraction patterns, but also how the scattering signals were distributed inside individual diffraction rings and how their distribution changed over time. This deeper level of analysis revealed changes in the tantalum’s lattice orientation, or texture, taking place in about one-tenth of a billionth of a second. It also showed whether the lattice was undergoing twinning or slip over a wide range of shock pressures – right up to the point where the metal melts. The team discovered that as the pressure increased, the dominant type of deformation changed from twinning to slip deformation.

    Wehrenberg said the results of this study are directly applicable to Lawrence Livermore’s efforts to model both plasticity and tantalum at the molecular level.

    These experiments, he said, “are providing data that the models can be directly compared to for benchmarking or validation. In the future, we plan to coordinate these experimental efforts with related experiments on LLNL’s National Ignition Facility that study plasticity at even higher pressures.”

    In addition to LLNL and SLAC, researchers from the University of Oxford, the DOE’s Los Alamos National Laboratory and the University of York contributed to this study. Funding for the work at SLAC came from the DOE Office of Science. LCLS is a DOE Office of Science User Facility.

    See the full article here .

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 9:19 am on August 22, 2017 Permalink | Reply
    Tags: , , Human interference in the deep sea could already be outpacing our basic understanding of how it functions, , Shocking gaps in basic knowledge of deep sea life, U Oxford   

    From U Oxford: “Shocking gaps in basic knowledge of deep sea life” 

    U Oxford bloc

    Oxford University

    1
    No image caption or credit

    Human interference in the deep sea could already be outpacing our basic understanding of how it functions, University scientists have warned. As a result, without increased research and an immediate review of deep ocean conservation measures, the creatures that live there face an uncertain future.

    Vibrant, mysterious and often referred to as the ‘final frontier’, the deep sea floor is the largest habitat on Earth. This vast area, which lies below 200m and accounts for 60% of the surface of the planet, is home to an array of creatures. However, very little is known about how it functions and, in particular, how populations of deep sea creatures are interconnected.

    In a new review published in Molecular Ecology, scientists from the Department of Zoology at Oxford University have considered all knowledge published to date of deep sea invertebrates. The paper highlights the disparity between our basic knowledge of the ecology of deep sea animals and the growing impact of humans on the deep ocean.

    Over the last thirty years there have only been 77 population genetics studies published on invertebrate species, the type of animals that dominate these deep areas. Of these papers, the majority have focused on commercial species at the shallower end of the depth range of up to 1000m, and only one has been conducted on creatures that live deeper than 5000m. As a result, life in the depths of the ocean remains a relative mystery.

    The review attempts to use what little information there is to paint a cohesive picture of how populations of deep sea creatures are connected over depth and distance. Often animals are disconnected over a few hundred metres of depth but relatively well connected over a few 1000 km distance.

    Christopher Roterman, co-author and postdoctoral researcher in Oxford’s Department of Zoology, said: ‘Today humans have an unprecedented ability to effect the lives of creatures living in one of the most remote environments on earth – the deep sea. At a time where the exploitation of deep sea resources is increasing, scientists are still trying to understand basic aspects of the biology and ecology of deep sea communities.’

    The effects of human activity, such as pollution, destructive trawl-fishing, deep sea mining and climate change, appear to be intensifying, and increasingly affecting populations of seafloor invertebrates. The impacts on fragile, slow-growing coral gardens are of particular concern. As ecosystem engineers, corals are biodiversity hotspots, potentially as vital to the seabed as the rainforests are to the Earth.

    Christopher added: ‘Population genetics is an important tool that helps us to understand how deep sea communities function, and in turn how resilient they will be in the future to the increasing threat of human impacts. These insights can help governments and other stakeholders to figure out ways to control and sustainably manage human activities, to ensure a healthy deep sea ecosystem.’

    The researchers acknowledge that getting data from the deep sea is costly and logistically challenging. However, they stress that recent technological developments mean that more genetic information about populations can be collected than ever before.

    Michelle Taylor, co-author and senior postdoctoral researcher in Oxford’s Department of Zoology, said: ‘Next-generation sequencing allows us to scan larger and larger portions of an animal’s genome and at a lower cost. This makes deep sea population genetic studies less costly, and for many animals, the sheer volume of data these new technologies create means they can now be studied for the first time.

    ‘As scientists it is our duty to gather as much basic information about these creatures as we can and share it, and work with the people that set the rules of the seas – who have the power to make management decisions. We cannot bury our heads in the sand and think that people are not going to try and exploit resources in the deep sea, so science needs to catch up.’

    See the full article here.

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 3:45 pm on June 19, 2017 Permalink | Reply
    Tags: , , The end Triassic mass extinction which set the scene for the rise and age of the dinosaurs new Oxford University research has found, The Triassic extinction took place approximately 200 million years ago and was proceeded by the dinosaur era, U Oxford, Volcanoes and the dinosaurs   

    From Oxford: “Volcanic eruptions triggered dawn of the dinosaurs” 

    U Oxford bloc

    Oxford University

    19 Jun 2017

    1
    No image caption or credit.

    2
    Image of fossilized dinosaur eggs found in India, currently displayed at Indroda Fossil Park, Gandhinagar, Gujarat INDIA. Image credit: Wikimedia Commons

    Huge pulses of volcanic activity are likely to have played a key role in triggering the end Triassic mass extinction, which set the scene for the rise and age of the dinosaurs, new Oxford University research has found.

    Researchers from the Oxford University Department of Earth Science worked in collaboration with the Universities of Exeter and Southampton to trace the global impact of major volcanic gas emissions and their link to the end of the Triassic period. The findings link volcanism to the previously observed repeated large emissions of carbon dioxide that had a profound impact on the global climate, causing the mass extinction at the end of the Triassic Period, as well as slowing the recovery of animal life afterwards.

    The Triassic extinction took place approximately 200 million years ago, and was proceeded by the dinosaur era [This is confusing. Was it the beginning or the end?] One of the largest mass extinctions of animal life on record, the casualty list includes large crocodile-like reptiles and several marine invertebrates. The event also caused huge changes in land vegetation, and while it remains a mystery why the dinosaurs survived this event, they went on to fill the vacancies left by the now extinct wildlife species, alongside early mammals and amphibians. This mass extinction has long been linked to a large and abrupt release of carbon dioxide into the atmosphere, but the exact source of this emission has been unknown.

    ________________________________________________________________________

    “This research strengthens the link between the Triassic mass extinction and volcanic emissions of CO2. Showing episodic volcanic CO2 emissions as the likely driver of the extinction, enhances our understanding of this event, and potentially of other climate change episodes in Earth’s history.”

    Lawrence Percival, Lead author and Geochemistry Graduate student at Oxford University

    ________________________________________________________________________

    Following the discovery of volcanic rocks of the same age as the extinction, volcanic carbon dioxide (CO2) emissions had previously been suggested as an important contributor to this extinction event. Previous studies have also shown that this volcanism might have occurred in pulses, but the global extent and potential impact of these volcanic episodes has remained unknown. These volcanic rocks covered a huge area, across four continents, representing the Central Atlantic Magmatic Province (CAMP).

    By investigating the mercury content of sedimentary rocks deposited during the extinction, the study findings revealed clear links in the timing of CAMP volcanism and the end-Triassic extinction. Volcanoes give off mercury gas emissions, which spread globally through the atmosphere, before being deposited in sediments. Any sediments left during a large volcanic event would therefore be expected to have unusually high mercury content.

    The team sourced six sediment deposits were sourced from the UK, Austria, Argentina, Greenland, Canada and Morocco, and their mercury levels analysed. Five of the six records showed a large increase in mercury content beginning at the end-Triassic extinction horizon, with other peaks observed between the extinction horizon and the Triassic–Jurassic boundary, which occurred approximately 200 thousand years later.

    Elevated mercury emissions also coincided with previously established increases in atmospheric CO2 concentrations, indicating CO2 release from volcanic degassing.

    Lawrence Percival, Lead author and Geochemistry Graduate student at Oxford University, said: ‘These results strongly support repeated episodes of volcanic activity at the end of the Triassic, with the onset of volcanism during the end-Triassic extinction.

    ‘This research greatly strengthens the link between the Triassic mass extinction and volcanic emissions of CO2. This, further evidence of episodic emissions of volcanic CO2 as the likely driver of the extinction, enhances our understanding of this event, and potentially of other climate change episodes in Earth’s history.’

    More information: Lawrence M. E. Percival el al., “Mercury evidence for pulsed volcanism during the end-Triassic mass extinction,” PNAS (2017). http://www.pnas.org/cgi/doi/10.1073/pnas.1705378114

    See the full article here.

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 4:05 pm on April 20, 2017 Permalink | Reply
    Tags: , Focused Ion Beam Milling, , U Oxford   

    From Oxford: “Widely used engineering technique has unintended consequences new research reveals” 

    U Oxford bloc

    Oxford University

    1

    20 Apr 2017

    A technique that revolutionised scientists’ ability to manipulate and study materials at the nano-scale may have dramatic unintended consequences, new Oxford University research reveals.

    Focused Ion Beam Milling (FIB) uses a tiny beam of highly energetic particles to cut and analyse materials smaller than one thousandth of a stand of human hair.

    This remarkable capability transformed scientific fields ranging from materials science and engineering to biology and earth sciences. FIB is now an essential tool for a number of applications including; researching high performance alloys for aerospace engineering, nuclear and automotive applications and for prototyping in micro-electronics and micro-fluidics.

    FIB was previously understood to cause structural damage within a thin surface layer (tens of atoms thick) of the material being cut. Until now it was assumed that the effects of FIB would not extend beyond this thin damaged layer. Ground-breaking new results from the University of Oxford demonstrate that this is not the case, and that FIB can in fact dramatically alter the material’s structural identity. This work was carried out in collaboration with colleagues from Argonne National Laboratory, USA, LaTrobe University, Australia, and the Culham Centre for Fusion Energy, UK.

    In research newly published in the journal Scientific Reports, the team studied the damage caused by FIB using a technique called coherent synchrotron X-ray diffraction. This relies on ultra-bright high energy X-rays, available only at central facilities such as the Advanced Photon Source at Argonne National Lab, USA. These X-rays can probe the 3D structure of materials at the nano-scale. The results show that even very low FIB doses, previously thought negligible, have a dramatic effect.

    Felix Hofmann, Associate Professor in Oxford’s Department of Engineering Science and lead author on the study, said, ‘Our research shows that FIB beams have much further-reaching consequences than first thought, and that the structural damage caused is considerable. It affects the entire sample, fundamentally changing the material. Given the role FIB has come to play in science and technology, there is an urgent need to develop new strategies to properly understand the effects of FIB damage and how it might be controlled.’

    Prior to the development of FIB, sample preparation techniques were limited, only allowing sections to be prepared from the material bulk, but not from specific features. FIB transformed this field by making it possible to cut out tiny coupons from specific sites in a material. This progression enabled scientists to examine specific material features using high-resolution electron microscopes. Furthermore it has made mechanical testing of tiny material specimens possible, a necessity for the study of dangerous or extremely precious materials.

    Although keen for his peers to heed the serious consequence of FIB, Professor Hofmann said, ‘The scientific community has been aware of this issue for a while now, but no one (myself included) realised the scale of the problem. There is no way we could have known that FIB had such invasive side effects. The technique is integral to our work and has transformed our approach to prototyping and microscopy, completely changing the way we do science. It has become a central part of modern life.’

    Moving forward, the team is keen to develop awareness of FIB damage. Furthermore, they will build on their current work to gain a better understanding of the damage formed and how it might be removed. Professor Hofmann said, ‘We’re learning how to get better. We have gone from using the technique blindly, to working out how we can actually see the distortions caused by FIB. Next we can consider approaches to mitigate FIB damage. Importantly the new X-ray techniques that we have developed will allow us to assess how effective these approaches are. From this information we can then start to formulate strategies for actively managing FIB damage.’

    See the full article here.

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 8:57 am on October 22, 2016 Permalink | Reply
    Tags: , , , U Oxford   

    From Oxford: “The universe is expanding at an accelerating rate — or is it?” 

    U Oxford bloc

    Oxford University

    21 October 2016
    Stuart Gillespie

    1
    Researchers analysed a database of supernovae — the spectacular thermonuclear explosions of dying stars. Image credit: University of Oxford; Shutterstock.

    Five years ago, the Nobel Prize in Physics was awarded to three astronomers for their discovery, in the late 1990s, that the universe is expanding at an accelerating pace.

    Their conclusions were based on analysis of Type Ia supernovae – the spectacular thermonuclear explosions of dying stars – picked up by the Hubble space telescope and large ground-based telescopes. It led to the widespread acceptance of the idea that the universe is dominated by a mysterious substance named ‘dark energy’ that drives this accelerating expansion.

    Now, a team of scientists led by Professor Subir Sarkar of Oxford University’s Department of Physics has cast doubt on this standard cosmological concept. Making use of a vastly increased data set – a catalogue of 740 Type Ia supernovae, more than ten times the original sample size – the researchers have found that the evidence for acceleration may be flimsier than previously thought, with the data being consistent with a constant rate of expansion.

    The study is published in the Nature journal Scientific Reports.

    Professor Sarkar, who also holds a position at the Niels Bohr Institute in Copenhagen, said: ‘The discovery of the accelerating expansion of the universe won the Nobel Prize, the Gruber Cosmology Prize, and the Breakthrough Prize in Fundamental Physics. It led to the widespread acceptance of the idea that the universe is dominated by “dark energy” that behaves like a cosmological constant – this is now the “standard model” of cosmology.

    ‘However, there now exists a much bigger database of supernovae on which to perform rigorous and detailed statistical analyses. We analysed the latest catalogue of 740 Type Ia supernovae – over ten times bigger than the original samples on which the discovery claim was based – and found that the evidence for accelerated expansion is, at most, what physicists call “3 sigma”. This is far short of the 5 sigma standard required to claim a discovery of fundamental significance.

    An analogous example in this context would be the recent suggestion for a new particle weighing 750 GeV based on data from the Large Hadron Collider at CERN. It initially had even higher significance – 3.9 and 3.4 sigma in December last year – and stimulated over 500 theoretical papers. However, it was announced in August that new data shows that the significance has dropped to less than 1 sigma. It was just a statistical fluctuation, and there is no such particle.’

    There is other data available that appears to support the idea of an accelerating universe, such as information on the cosmic microwave background [CMB] – the faint afterglow of the Big Bang – from the Planck satellite.

    CMB per ESA/Planck
    CMB per ESA/Planck

    However, Professor Sarkar said: ‘All of these tests are indirect, carried out in the framework of an assumed model, and the cosmic microwave background is not directly affected by dark energy. Actually, there is indeed a subtle effect, the late-integrated Sachs-Wolfe effect, but this has not been convincingly detected.

    ‘So it is quite possible that we are being misled and that the apparent manifestation of dark energy is a consequence of analysing the data in an oversimplified theoretical model – one that was in fact constructed in the 1930s, long before there was any real data. A more sophisticated theoretical framework accounting for the observation that the universe is not exactly homogeneous and that its matter content may not behave as an ideal gas – two key assumptions of standard cosmology – may well be able to account for all observations without requiring dark energy. Indeed, vacuum energy is something of which we have absolutely no understanding in fundamental theory.’

    Professor Sarkar added: ‘Naturally, a lot of work will be necessary to convince the physics community of this, but our work serves to demonstrate that a key pillar of the standard cosmological model is rather shaky. Hopefully this will motivate better analyses of cosmological data, as well as inspiring theorists to investigate more nuanced cosmological models. Significant progress will be made when the European Extremely Large Telescope makes observations with an ultrasensitive “laser comb” to directly measure over a ten to 15-year period whether the expansion rate is indeed accelerating.’

    See the full article here .

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    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 10:25 am on July 13, 2016 Permalink | Reply
    Tags: , , Red geysers in MaNGA survey, U Oxford   

    From U Oxford: “Scientists discover how supermassive black holes keep galaxies turned off” 

    U Oxford bloc

    Oxford University

    25 May 2016
    No writer credit found

    1

    An international team of scientists has identified a common phenomenon in galaxies that could explain why huge numbers of them turn into cosmic graveyards.

    Galaxies begin their existence as lively and colourful spiral galaxies, full of gas and dust, and actively forming bright new stars. However, as galaxies evolve, they quench their star formation and turn into featureless deserts, devoid of fresh new stars, and generally remain as such for the rest of their evolution. But the mechanism that produces this dramatic transformation and keeps galaxies turned off, is one of the biggest unsolved mysteries in galaxy evolution.

    Now, thanks to the new large SDSS-IV MaNGA survey of galaxies, a collaborative effort led by the University of Tokyo and involving the University of Oxford has discovered a surprisingly common new phenomenon in galaxies, dubbed red geysers, that could explain how the process works.

    Researchers interpret the red geysers as galaxies hosting low-energy supermassive black holes which drive intense interstellar winds. These winds suppress star formation by heating up the ambient gas found in galaxies and preventing it to cool and condense into stars.

    The research is published in the journal Nature.

    Lead author Dr Edmond Cheung, from the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe, said: ‘Stars form from the gas, but in many galaxies stars were found not to form despite an abundance of gas. It was like having deserts in densely clouded regions. We knew quiescent galaxies needed some way to suppress star formation, and now we think the red geysers phenomenon may represent how typical quiescent galaxies maintain their quiescence.’

    ‘Stars form from the gas, a bit like the drops of rain condense from the water vapour. And in both cases one needs the gas to cool down, for condensation to occur. But we could not understand what was preventing this cooling from happening in many galaxies,’ said Co-author Dr Michele Cappellari, from the Department of Physics at Oxford University. ‘But when we modelled the motion of the gas in the red geysers, we found that the gas was being pushed away from the galaxy centre, and escaping the galaxy gravitational pull.’

    ‘The discovery was made possible by the amazing power of the ongoing MaNGA galaxy survey,’ said Dr Kevin Bundy, from the University of Tokyo, the overall leader of the collaboration. ‘The survey allows us to observe galaxies in three dimensions, by mapping not only how they appear on the sky, but also how their stars and gas move inside them.’

    Using a near-dormant distant galaxy named Akira as a prototypical example, the researchers describe how the wind’s driving mechanism is likely to originate in Akira’s galactic nucleus. The energy input from this nucleus, powered by a supermassive black hole, is capable of producing the wind, which itself contains enough mechanical energy to heat ambient, cooler gas in the galaxy and thus suppress star formation.

    The researchers identified an episodic quality to these jets of wind, leading them to the name red geysers (with ‘red’ colour due to the lack of blue young stars). This phenomenon, discussed in the paper with reference to Akira, appears surprisingly common and could be generally applicable to all quiescent galaxies.

    The study made use of optical imaging spectroscopy from the Sloan Digital Sky Survey-IV Mapping Nearby Galaxies at Apache Point Observatory (SDSS-IV MaNGA) programme

    SDSS Telescope at Apache Point, NM, USA
    SDSS Telescope at Apache Point, NM, USA

    See the full article here.

    Please help promote STEM in your local schools.

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 5:56 pm on January 11, 2016 Permalink | Reply
    Tags: , , , , U Oxford   

    From U Oxford: “Exploring spiral-host radio galaxies” 

    U Oxford bloc

    Oxford University

    OUP blog bloc

    Temp 1
    Hercules. A radio galaxy hosted in a massive elliptical galaxy. Radio emission, overplotted on the optical image, is shown in pink highlighting large jet-lobe structure. A Milky Way-sized spiral galaxy is marked by white ellipse. Image adapted from a Hubble Heritage Release. Credit: NASA, ESA, S. Baum and C. O’Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA).

    January 9th 2016
    Veeresh Singh

    Few know exactly what radio galaxies are, much less what factors influence their formation. Even so, new discoveries have brought these astronomical structures into the public eye, and researchers continue to investigate the mysterious conditions of their existence. Below, Veeresh Singh addresses the substance and implications of such discoveries, further elaborating on his research paper, Discovery of rare double-lobe radio galaxies hosted in spiral galaxies, recently published in Monthly Notices of Royal Astronomical Society.

    What are radio galaxies?

    A galaxy is a gigantic system possessing billions of stars, vast amounts of gas, dust, and dark matter held together by gravitational attraction. The typical size of galaxies can be anywhere from a few tens-of-thousands to a few hundreds-of-thousands of light-years. Our own solar system is part of a galaxy named the “Milky Way.” Observations made from telescopes have shown that our universe is full of billions of galaxies that are of different shapes (e.g., spiral, spheroidal, elliptical and irregular).

    Studies on the motion of stars, gas, and dust close to the core of galaxies reveal that almost all galaxies host Super Massive Black Holes(SMBHs), which are millions to billions of times the mass of our Sun in their centres. In simple words, black holes are gravitationally collapsed systems in which gravity is so strong that even light cannot escape from the surface of their sphere of influence. Whenever matter is available in the vicinity of SMBHs, they accrete matter via gravitational pull and also eject a fraction of accreted matter—through outflowing bipolar collimated jets formed via magneto-hydro-dynamical processes.

    Galaxies having accreting SMBH are called “active galaxies.” Some of these active galaxies exhibit radio-emitting overflowing jets extending well beyond the size of host galaxies’ stellar distribution. These active galaxies are called “radio galaxies.” As the name itself suggests, radio galaxies are powerful emitters of radio emissions and show radio morphology that consists of a core producing a pair of bipolar collimated jets terminating in two lobes. The radio core coincides with the centre of the host galaxy seen in optical light but the jet-lobe extends well-beyond the host galaxy and entrenches into the empty space between galaxies, i.e. “intergalactic region.” Radio galaxies are one of the largest structures in the Universe and the total end-to-end radio size can range from thousands to millions of light years.

    What is the shape of hosts of radio galaxies?

    Traditionally, radio galaxies are found to be hosted in massive, gas-poor elliptical galaxies characterised by feeble star formation rates. It is believed that the relativistic jets emanating from the accreting SMBHs at their centres can easily plough through the rarer InterStellar Medium (ISM) of elliptical galaxies and reach scales of up to millions of light years.

    How common are spiral-host radio galaxies?

    Unlike conventional radio galaxies, which are almost always found in elliptical galaxies, we have discovered four radio galaxies (named in astronomical parlance as J0836+0532, J1159+5820, J1352+3126, and J1649+2635) that are found to be hosted in spiral galaxies. These extremely rare and enigmatic galaxies were found in a systematic search that combined a whopping 187,000 optical images of spiral galaxies from the Sloan Digital Sky Survey (SDSS) DR7 with the radio-emitting sources from two radio-surveys viz. ‘Faint Images of the Radio Sky at Twenty-cm (FIRST)’ and ‘NRAO VLA Sky Survey (NVSS)’ both carried out with the Very Large Array (VLA) radio telescope in the United States.

    SDSS Telescope
    SDSS telescope at Apache Point, NM, USA

    NRAO VLA
    NRAO/VLA

    This is the first attempt to carry out an extensive systematic search to find spiral-host radio galaxies using largest existing sky surveys. Before this work, only four examples of spiral-host radio galaxies were known and three of these were discovered serendipitously.

    What causes spiral galaxies to become radio-loud?

    Understanding the formation of these newly discovered spiral-host radio galaxies is a challenge in the present theoretical model. Using current available data on these sources it is speculated that the formation of spiral-host double-lobe radio galaxies can be attributed to more than one factor, such as the occurrence of strong interactions or mergers with other galaxies, and the presence of an unusually massive SMBH, while keeping the spiral structures intact. Notably, all these galaxies contain an SMBH at their centre with a mass of approximately a billion times that of the Sun.

    2
    J083+0532, a spiral galaxy with million-light-years large radio emitting jet-lobe structure. Upper panel shows contours of radio emission overplotted on the optical image from Sloane Digital Sky Survey (SDSS). Lower left panel represents the false colour radio image while lower right panel shows SDSS optical image. Image used with permission.

    Since only one among four was found in a cluster environment, it implies that the large scale environment is not the prime reason for triggering radio emission. Mergers or interactions could be more likely. In fact, two galaxies—J1159+5820 and J1352+3126—in this study show evidence of mergers. However, another two galaxies—J0836+0532 and J1649+2635—are face-on spirals and do not show any detectable signature of disturbance caused by a recent merger with another galaxy.

    How are galaxies currently being studied?

    In order to attain a better understanding of the formation of these galaxies, the research team is observing these galaxies at different frequencies. The team has already acquired low frequency radio observations with the Giant Metrewave Radio Telescope (GMRT) in India.

    Giant Metrewave Radio Telescope
    GMRT

    The multi-frequency radio observations will enable the study of the radio structures at different spatial scales and also in estimating the time elapsed since the radio emitting jets were ejected from the centre of each galaxy.

    What does the discovery of spiral-host radio galaxies mean to upcoming surveys?

    The discovery of these spiral-host radio galaxies can be considered as a test bed to find rare populations of spiral-host double-lobe radio galaxies in the distant universe using more sensitive surveys from upcoming facilities such as the Large Synoptic Survey Telescope (LSST) and the Square Kilometre Array (SKA).

    LSST Exterior
    LSST Interior
    LSST Camera
    LSST, the building which will house it, and the camera being built at SLAC

    SKA ASKAP telescope

    SKA Murchison Widefield Array
    From SKA, ASKAP and part of the Murchison Wide Field Array

    See the full article here.

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 3:17 pm on January 9, 2016 Permalink | Reply
    Tags: , , Safer surgery, U Oxford   

    From U Oxford: “Making patients safer in surgery” 

    U Oxford bloc

    Oxford University

    5 Jan 2016
    No writer credit found

    Temp 1

    Surgery is getting safer thanks to research by an Oxford University team that has brought together two previously competing theories about how best to protect patients.

    Previous attempts to improve patient safety in surgery used one of two approaches. Some investigators tried to improve teamwork and communication by training team members to interact better, using principles developed in the aviation industry. Others have focused on the systems of work and used industrial quality improvement techniques to rationalise these and remove or modify steps which carry a high risk of error.

    A programme of studies, funded by the Programme Grants for Applied Research section of the National Institute for Health Research (NIHR), was carried out over four years by the Department of Surgical Sciences at Oxford University. It is believed to be the largest, direct observational study of surgical team performance during whole procedures ever completed.

    The team ran five identical studies comparing the culture approach, two different systems approaches and two combined culture/system approaches. They found that the combined system/culture approaches were clearly better than either of the single approaches. This is an important idea which may change practice internationally.

    Two new papers, published in the journal Annals of Surgery, outline the results of their research.

    Professor Peter McCulloch, Principal Investigator of the project and head of the Quality, Reliability, Safety and Teamwork Unit (QRSTU), said: ‘One set of interventions tried to modify the culture of the team and the other tried to improve the system of work. No one had asked which of these was better, or whether combining the approaches would be more effective. It is not enough to just fix the system and it’s not enough to just train the team. You have to do both.’

    In addition, the research showed that clinical staff who receive teamwork training become better motivated and more knowledgeable about safety risks, but are not able to change their working practices. Those who are helped to improve their system are able to do this, but are not educated or motivated to focus on the changes which will be most beneficial for patients. Staff who received the combined intervention developed more ambitious projects and demanded more help from the experts.

    Lorna Flynn, Human Factors Research Assistant within QRSTU and first author of the second, qualitative paper, commented: ‘In addition to telling us that integrated approaches targeting systems and culture produce the best outcomes; our research has highlighted the fact that frontline staff do not have the time or means to address patient safety issues alone. Whilst frontline staff will possess local in-depth knowledge about their systems and working context, effective improvement work still requires substantial support from experts in the fields of Human Factors/Ergonomics and Quality Improvement. These findings have implications for practice in organisations where frontline clinical staff are often expected to do this work as part of their everyday clinical work; such an approach is not going to be sufficient in making significant change to patient safety unless healthcare organisations engage with experts in these fields.’

    The papers, Combining systems and teamwork approaches to enhance the effectiveness of safety improvement interventions in surgery: the Safer Delivery of Surgical Services (S3) and The Safer Delivery of Surgical Services Programme (S3): explaining its differential effectiveness and exploring implications for improving quality in complex systems, are published in the journal Annals of Surgery.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
  • richardmitnick 11:15 am on October 3, 2015 Permalink | Reply
    Tags: , , , U Oxford   

    From Oxford: “Behind the scenes of creating the ground-breaking Ebola vaccine” 

    U Oxford bloc

    Oxford University

    Professor Adrian Hill of Oxford’s Jenner Institute led the first clinical trial of a successful Ebola virus vaccine last year. To target the outbreak his remarkable team compressed a process that takes six months into six weeks.

    1

    The recent Ebola outbreak was the deadliest since the virus’ discovery in the 1970s. Fortunately Professor Adrian Hill, Director of Oxford’s Jenner Institute, and his team managed to create a vaccine response in record time.

    At his Alumni Weekend talk, Professor Hill described the desperate situation that West Africa was in last year. Ebola was in the news every day, with death tolls spiralling up through the summer. There were no vaccines known to protect against Ebola, or drugs to treat those infected at the time. Promising vaccine candidates did exist in the US, but only one had been tested in humans and had been subsequently abandoned.

    Usually Ebola outbreaks have been contained using the traditional methods of containment in Central Africa, but it was spreading through the continent rapidly – in Guinea, Sierra Leone, and Liberia – in 2014. With no vaccines ready to be tested out in West Africa the situation was grave, Professor Hill explained.

    2

    The resulting ambitious trial at Oxford was funded by the Wellcome Trust, Medical Research Council and Department for International Development. Phase one began in mid-September 2014 with 60 volunteers, and a further 80 out in Mali in October – after the team was swamped with volunteers anxious to help.

    For the successful vaccine Professor Hill’s team used a single Ebola gene in a chimpanzee adenovirus to generate an immune response. As it did not contain any infectious virus material, it did not cause the patient to become infected. The trial’s efficiency exceeded all expectations, with a novel vaccine ready from the trial to finished product in nine months.

    3

    The researchers then used an innovative trial design in West Africa, in which the family, friends and contacts in a ‘ring’ around an Ebola patient would be given the vaccine. In March 2015, the first infected individuals were identified and the ring vaccination began in Guinea, which continues to have the majority of cases. Both this ‘ring’ approach and the vaccine were a great success.

    Looking to the future, Professor Hill reflected that it would be wonderful if Britain could manufacture vaccines ‘on a significant scale’ once again. David Cameron has promised £20million to protect Britain from future pandemics this year, but how that money will be allocated has not yet been decided.

    Professor Hill explained more broadly the challenges left facing vaccination development. On the positive side, only two countries in the world are left with polio, and smallpox has been eradicated. This leaves the big three vaccinations to find as HIV/AIDS, malaria, and an improved TB jab.

    In terms of Ebola itself, the vaccine that Professor Hill’s team worked on was for the Zaire strain, but there still remains to be one for the Sudan strain. He pointed out that there will ‘almost certainly’ be more major outbreaks, especially as Africa’s population increases, people travel more and cities expand.

    For all of the team’s hard work, the University decided that their contributions should be recognised, and commissioned a University of Oxford Ebola medal this summer. The medals were presented by the Vice-Chancellor, Professor Andrew Hamilton, and the head of the Nuffield Department of Clinical Medicine, Professor Peter Ratcliffe. Professor Hamilton reflected: ‘The work of the team was absolutely critical. These kinds of outbreaks can arise at any time and we need to be ready to respond. They responded magnificently.’

    For further details about the Jenner Institute click here.

    Photographs courtesy of Oxford University Images

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Oxford campus

    Oxford is a collegiate university, consisting of the central University and colleges. The central University is composed of academic departments and research centres, administrative departments, libraries and museums. The 38 colleges are self-governing and financially independent institutions, which are related to the central University in a federal system. There are also six permanent private halls, which were founded by different Christian denominations and which still retain their Christian character.

    The different roles of the colleges and the University have evolved over time.

     
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