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  • richardmitnick 11:58 am on May 29, 2017 Permalink | Reply
    Tags: , , , , Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma in the Canaries Spain, , , Spain,   

    From Manu: Stephan’s quintet 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    1
    This image is interesting for two things. First, teaches us that effectively galaxies may, throughout its existence, go through phases of intense interaction with other galaxies, interaction that produces an alteration of the delicate balance of forces that keeps the stars in their orbits. In many cases the galaxies are deformed and part of its stars look released abroad producing long tails and bows. At this stage of interacting galaxies also tend to experience a period of intense star formation and, more rarely, maybe her central black hole is activated by turning her into a quasar.

    The other interesting thing that tells us this picture of Stephan’s quintet is that things are not always what they seem. You will note the biggest galaxy has a color a lot more blue than the other four, clearly more yellow. This is because this galaxy is only 40 million light-years away, much closer to us than the other, located some 250 million light-years away. Just by pure chance his image projected above the other. The Quintet, strictly speaking, it should be called quartet!

    Galaxies form groups that may contain a few hundreds of galaxies, of all sizes and shapes. We too, as part of the milky way, we belong to a set of 50 galaxies called a local group.

    Local Group. Andrew Z. Colvin 3 March 2011

    Due to its own gravitational pull, the galaxies of a group are attracted to each other and to avoid collapse and form a single huge object, must constantly be moving within the same group.
    This continual movement can make galaxies collide between them, as is clear in this image taken with Osiris of a small group called Stephan’s quintet.

    2
    Galactic Wreckage in Stephan’s Quintet.
    A clash among members of a famous galaxy quintet reveals an assortment of stars across a wide color range, from young, blue stars to aging, red stars.
    This portrait of Stephan’s Quintet, also known as Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard NASA’s Hubble Space Telescope. Stephan’s Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy about seven times closer to Earth than the rest of the group.
    Three of the galaxies have distorted shapes, elongated spiral arms, and long, gaseous tidal tails containing myriad star clusters, proof of their close encounters. These interactions have sparked a frenzy of star birth in the central pair of galaxies. This drama is being played out against a rich backdrop of faraway galaxies.
    The image, taken in visible and near-infrared light, showcases WFC3’s broad wavelength range.

    NASA/ESA Hubble WFC3

    NASA/ESA Hubble Telescope

    The colors trace the ages of the stellar populations, showing that star birth occurred at different epochs, stretching over hundreds of millions of years. The camera’s infrared vision also peers through curtains of dust to see groupings of stars that cannot be seen in visible light.
    NGC 7319, at top right, is a barred spiral with distinct spiral arms that follow nearly 180 degrees back to the bar. The blue specks in the spiral arm at the top of NGC 7319 and the red dots just above and to the right of the core are clusters of many thousands of stars. Most of the quintet is too far away even for Hubble to resolve individual stars.
    Continuing clockwise, the next galaxy appears to have two cores, but it is actually two galaxies, NGC 7318A and NGC 7318B. Encircling the galaxies are young, bright blue star clusters and pinkish clouds of glowing hydrogen where infant stars are being born. These stars are less than 10 million years old and have not yet blown away their natal cloud. Far away from the galaxies, at right, is a patch of intergalactic space where many star clusters are forming.
    NGC 7317, at bottom left, is a normal-looking elliptical galaxy that is less affected by the interactions.
    Sharply contrasting with these galaxies is the dwarf galaxy NGC 7320 at upper left. Bursts of star formation are occurring in the galaxy’s disk, as seen by the blue and pink dots. In this galaxy, Hubble can resolve individual stars, evidence that NGC 7320 is closer to Earth.
    NGC 7320 is 40 million light-years from Earth. The other members of the quintet reside 290 million light-years away in the constellation Pegasus.
    These farther members are markedly redder than the foreground galaxy, suggesting that older stars reside in their cores. The stars’ light also may be further reddened by dust stirred up in the encounters.
    Spied by Edouard M. Stephan in 1877, Stephan’s Quintet is the first compact group ever discovered.
    WFC3 observed the quintet in July and August 2009. The composite image was made by using filters that isolate light from the blue, green, and infrared portions of the spectrum, as well as emission from ionized hydrogen.
    These Hubble observations are part of the Hubble Servicing Mission 4 Early Release Observations. NASA astronauts installed the WFC3 camera during a servicing mission in May to upgrade and repair the 19-year-old Hubble telescope.
    Denoised by uploader.
    Date July 2009 and August 2009
    Source http://www.hubblesite.org/newscenter/archive/releases/2009/25/image/x/ (direct link)
    Author NASA, ESA, and the Hubble SM4 ERO Team

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain

    See the full article here .

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  • richardmitnick 11:31 am on May 29, 2017 Permalink | Reply
    Tags: , , Doped diamond, , , Superposition   

    From COSMOS: “Doped diamond may lead to everyday quantum computers” 

    Cosmos Magazine bloc

    COSMOS

    29 May 2017
    Andrew Masterson

    1
    Precise placement of atoms in a diamond lattice may be a handy technique for quantum computer manufacture. Victor Habbick Visions / Getty

    Quantum computers are still halfway mythical, but they are moving closer to reality step by tiny step.

    One of the most widely favoured structures for building viable quantum computers is a diamond surface dotted with irregularities only a couple of atoms wide.

    The problem researchers face, however, is making sure those irregularities – essentially atom-scale holes and accompanying bits of atom-wide foreign material – are drilled into the diamond substrate in exactly the right spot.

    A report at Nature Communications by a team from MIT, Harvard University, and Sandia National Laboratories, in the US, covers a new method of doing so, creating the “defects” in the diamond crystal structure within 50 nanometres of their optimal locations.

    The precise placement of the irregularities – known as “dopant-vacancies” in the business – is a critical outcome if quantum computers are ever to end up on the market.

    This is because the combination of a tiny hole and a couple of atoms of non-diamond matter – nitrogen, for instance – can be engineered to act as a qubit, the fundamental element of quantum computing.

    At the heart of a qubit is a subatomic particle that can simultaneously occupy a number of contradictory states – on, off, and a “superposition” of both together, for instance. The combination of the hole, the foreign atoms, and the light refracted through the diamond combine to create an elegant qubit.

    At least, theoretically. To date, most experimental work has been done using nitrogen dopant-vacancies. These have the advantage of being able to maintain superposition longer than other candidates, but emit light across a broad range of frequencies, making information retrieval difficult.

    The MIT-Harvard-Sandia team, led by Tim Schröder, experimented instead with silicon-based defects, which emit light in a much narrower range. That advantage, however, comes with its own challenge: the silicon dopant-vacancies need to be chilled to within a few thousands of a degree above absolute zero if they are to maintain a superposition for any length of time.

    That remains a challenge still to be met, however. The import of the current study, published in the journal Nature Communications, lies in the increase in the accuracy of positioning the defects in the diamond.

    To achieve this, scientists at MIT and Harvard first created a sliver of diamond only 200 nanometres thick. Onto this they etched tiny cavities.

    The substrate was then sent to the Sandia laboratories, where each cavity was bombarded with 20 to 30 silicon ions. The process led to only about two percent of the cavities attracting silicon residents.

    Back at MIT a second new process was employed. The diamond sliver was heated to 1000 ºC, at which temperature its component lattice became malleable, allowing the researchers to align more cavities with more silicon particles – taking the total number of dopant-vacancies to 20%.

    Most of the irregularities thus produced were within 50 nanometres of their optimal position, and shone at around 85% of optimal brightness.

    A quantum computer in every household is still a long way off, but this study marks a potentially important step in the journey.

    See the full article here .

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  • richardmitnick 11:15 am on May 29, 2017 Permalink | Reply
    Tags: A bubble around Earth, , , , , ,   

    From COSMOS: “Radio signals may have created a protective magnetic bubble around Earth” 

    Cosmos Magazine bloc

    COSMOS

    29 May 2017
    No writer credit found.

    Very low frequency radio communications with deep-sea submarines may keep out high energy electrons and protons.

    2

    Very low frequency (VLF) radio communications – the kind we use to communicate with submarines, far below sea level – could be creating a bubble around Earth that protects against high levels of space radiation.

    NASA’s Van Allen Probes have observed the extent to which excess space radiation, in the form of highly-charged particles, moves into our near-Earth environment.

    Van Allen Belts NASA GSFC

    NASA Van Allen Probes

    A new paper at SpringerLink from researchers at the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder, US, observes that the outer limit of the bubble of radio waves around the planet caused by VLF communication is about the same as the inner limit of the Van Allen radiation belts – layers of charged particles held in place by Earth’s magnetic fields.

    The paper suggests that this may not be a coincidence – that perhaps our radio waves are impacting how particles move in space. Indeed, in the 1970s, before VLF communication was in widespread use, it appears radiation was present further into our near-Earth atmosphere.

    If this analysis is accurate, VLF transmission could be used to remove excess radiation from the Earth’s atmosphere. Further research is underway to test the impact of VLF transmissions on charged particles in our upper atmosphere.

    See the full article here .

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  • richardmitnick 10:46 am on May 29, 2017 Permalink | Reply
    Tags: , Cleveland Volcano, , ,   

    From Science Times: “The Bogoslof Volcano Eruption In the Aleutian Islands In Alaska May Hamper The Activity Of The Flights” 

    Science Times

    Science Times

    May 29, 2017
    partha das

    1
    (Photo : NASA via Getty Images) In this photo provided by NASA, The eruption of the Cleveland Volcano is seen as photographed by an Expedition 13 crewmember on the International Space Station May 23, 2009 in the Aleutian Islands, Alaska. The Cleveland Volcano has erupted again yesterday sending a cloud of ash 15,000 feet into the sky according to reports on December 30, 2011.

    Mount Cleveland (also known as Cleveland Volcano) is a nearly symmetrical stratovolcano on the western end of Chuginadak Island, which is part of the Islands of Four Mountains just west of Umnak Island in the Fox Islands of the Aleutian Islands of Alaska.

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    From the USGS caption: Mount Cleveland forms the western half of Chuginadak Island in the central Aleutian Islands. This symmetrical, 1,730-m (5,676 ft)-high stratovolcano and has been the site of numerous eruptions in the last two centuries; the most recent eruption occurred in 1994. In 1944, a U.S. Army serviceman was reportedly killed by an eruption from Mount Cleveland.
    Date 24 July 1994
    Source http://pubs.usgs.gov/dds/dds-40/ (image 94 of Volcanoes of the Alaska Peninsula and Aleutian Islands—Selected Photographs)
    Author M. L. Harbin of the University of Alaska Fairbanks in a joint program, the Alaska Volcano Observatory, with the USGS[1]

    The eruption of the Bogoslof Volcano in the Aleutian Islands may disrupt the activity of the important flights. The Alaska Volcano has been active for the last six months.

    For the last six months, the Bogoslof Volcano has been active and the last eruption took place on Sunday at 2:16 pm, Global News reported. This Alaska Volcano is situated in the Aleutian Islands in Alaska. The Sunday eruption lasted for 55 minutes and this ultimately sent one ash cloud that was 10,668 meters high, the Alaska Volcano Observatory stated.

    The increasing amount of ash from the Bogoslof Volcano can be very harmful to the jet engines as it can stop the engines. Ash coming out from the volcano of the southwest Alaska possesses a great threat for the airlines. The threat becomes acute when the cloud crosses the height of 6,096 meters. The airlines between the North America and the Asia mainly face the crisis.

    The previous Aviation Color Code was red after the Bogoslof Volcano eruption, though the current color is orange, according to the Alaska Volcano Observatory. No further ash emissions took place after the Sunday explosion. Before Sunday The Alaska Volcano last erupted on 17 May 2017. The eruption occurred at 10:32 pm and continued for almost 73 minutes and spewed ash into the air.

    The Aviation Color Code provides essential information about the Bogoslof Volcano. Now the important fact is this Color Code includes four colors and each color reflects the condition near the volcano. Here the red color indicates the eruption with a significant amount of ash into the air. The orange color says there is almost no emission of ash, though the eruption is under way.

    The U.S. News stated that reports from a pilot revealed the eruption of the Bogoslof Volcano on 17 May that formed a cloud of ash. The eruption sent the ash cloud 35,000 feet into the air. After this, the observatory issued warnings to the pilots. The important fact was the wind actually pushed the ash cloud southwest.

    This Alaska Volcano is a submarine stratovolcano. The eruption of the Bogoslof Volcano has been occurring periodically since the mid-December. The observatory opines that additional explosions with the high-altitude ash could happen at any time.

    See the full article here .

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    The Science Hub For The Internet…

    Sciencetimes.com prides itself in providing a complete informational and content package for science enthusiasts in the web who aim to remain updated and well-informed regarding a wide array of topics of their interest.

    We provide credible news & info., in-depth reference material about diverse subjects that matter to everyone. We are a source for original and timely science and research information as well as breaking news in the various fields we represent.

     
  • richardmitnick 10:15 am on May 29, 2017 Permalink | Reply
    Tags: , , , , , Citizen scientists in search of failed stars, , Hawaii, NASA Infrared Telescope facility Mauna Kea, , USA   

    From astrobites: “Citizen scientists in search of failed stars” 

    Astrobites bloc

    Astrobites

    May 29, 2017
    Ingrid Pelisoli

    Title: The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
    Authors: Marc J. Kuchner, Jacqueline K. Faherty, Adam C. Schneider et al.
    First Author’s Institution: NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory

    Status: Accepted to ApJL [open access]

    Not everyone can be a star. Brown dwarfs, for example, have failed on their attempt.

    Artist’s concept of a Brown dwarf [not quite a] star. NASA/JPL-Caltech

    These objects have masses below the necessary amount to reach pressure and temperature high enough to burn hydrogen into helium in their cores and thus earn the classification “star”. It’s not very long since we’ve learned of their existence. They were proposed in the 1960s by Dr. Shiv S. Kumar, but the first one was only observed many years later, in 1988 – and we are not even sure it is in fact a brown dwarf! We’ve only reached a substantial number of known brown dwarfs with the advent of infrared sky surveys, such as the Two Micron All Sky Survey (2MASS) and the Wide-field Infrared Survey Explorer (WISE).


    Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, and at the Cerro Tololo Inter-American Observatory near La Serena, Chile.

    NASA/WISE Telescope

    Discovering and characterising cold brown dwarfs in the solar neighbourhood is one of the primary science goals for WISE. There are two ways of doing that: 1) identifying objects with the colours of cold brown dwarfs; 2) identifying objects with significant proper motion. Brown dwarfs are relatively faint objects, so they need to be nearby to be detected. We can detect the movement of such nearby targets against background stars, which are so distant that they appear to be fixed on the sky. This movement is called proper motion. As the signal-to-noise ratio is not very good for such faint objects, the second method is the preferred one. However, single exposure WISE images are not deep enough to find most brown dwarfs. This is where today’s paper enters. The authors have launched a citizen science project called “Backyard Worlds: Planet 9” to search for high proper motion objects, including brown dwarfs and possible planets orbiting beyond Pluto, in the WISE co-add images. Co-add images are simply a sum of the single exposures images taking into account corrections to possible shifts between them. This increases signal-to-noise ratio and helps to detect faint targets. On today’s paper, they report the first discovery of their project: a new brown dwarf in the solar neighbourhood, which was identified only six days after the project was launched!

    Citizen science: a promising approach

    The idea behind citizen science is to engage numerous volunteers to tackle research problems that would otherwise be impractical or even impossible to accomplish. The Zooniverse community hosts lots of such projects, in disciplines ranging from climate science to history. Citizen science projects have made some remarkable discoveries in astronomy, such as KIC 8462852 (aka “Tabby’s Star”, “Boyajian’s star” or “WTF star”).

    3
    Tabby’s Star is mysteriously dimming again as reported by Fairborn Observatory in Arizona.
    (Photo : Unexplained/YouTube screenshot)

    In “Backyard Worlds: Planet 9”, volunteers are asked to examine short animations composed of difference images constructed from time-resolved WISE co-adds. The difference images are obtained subtracting the median of two subsequent images from the image to be analysed. This way, if an object does not significantly move, it will disappear from the analysed image with the subtraction, leaving only moving objects to be detected. The images are also divided into tiles small enough to be analysed on a laptop or cell phone screen. The classification task consists in viewing one animation, which is composed of four images, and identifying candidates for two types of moving objects: “movers” and “dipoles”. Movers are fast moving sources, that travel more than their apparent width over the course of WISE’s 4.5 year baseline. Dipoles are slower-moving sources that travel less than their apparent width, so that there will be a negative image right next to a positive image, since the subtraction of the object’s flux will only be partial. An online tutorial is provided to show how to identify such objects and distinguish them from artifacts such as partially subtracted stars or galaxies, and cosmic rays.

    The discovery: WISEA 1101+5400

    4
    Figure 1: Two co-adds of WISE data separated by 5 years showing how WISEA 1101+5400 has moved. The region shown is 2.0” x 1.6” in size. [Figure 2 from the paper]

    Five users reported a dipole on a set of images, which can be seen here, the first report taking place only six days after the project was launched. The object, called WISEA 1101+5400, can be seen on Figure 1. This source would be undetectable in single exposure images, while in these co-adds it is visible and obviously moving. Follow-up spectra were obtained 9 using the SpeX spectrograph on the 3 m NASA Infrared Telescope Facility (IRTF).

    NASA Infrared Telescope facility Mauna Kea, Hawaii, USA

    The average spectrum is shown on Figure 2. Both the object’s colours and the obtained spectra are consistent with a field T dwarf, a type of brown dwarf.

    5
    Figure 2: In black, the spectrum for WISEA 1101+5400. A field T5.5 brown dwarf, SDSS J0325+0425, is shown in red for comparison. Atomic and molecular opacity sources that define the T dwarf spectral class are indicated. [Figure 3 from the paper]

    Assuming WISEA 1101+5400 is the worst case scenario, i.e. about as faint an object as this survey is able to detect and with the minimum detectable proper motion, the authors estimate that “Backyard Worlds: Planet 9” has the potential to discover about a hundred new brown dwarfs. If WISEA 1101+5400 is not the worst case scenario, but objects even fainter or with lower proper motion can be found, this number could go up.

    Although the discovery of only one brown dwarf might not seem worthy of celebration, this discovery demonstrates the ability of citizen scientists to identify moving objects much fainter than the WISE single exposure limit. It is yet another proof that science could use the help of enthusiasts. So if you’re not doing anything now, why not take your pick at https://www.zooniverse.org/ and help a scientist?

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 9:41 am on May 29, 2017 Permalink | Reply
    Tags: , , , Background of gravitational waves expected from binary black hole events like GW150914, , , ,   

    From LIGO: “Background of gravitational waves expected from binary black hole events like GW150914” 

    LSC LIGO Scientific Collaboration

    LIGO Scientific Collaboration

    5.29.17 Presentation
    No writer credit found


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    Introduction
    It is an amazing time in the field of gravitational-wave astronomy—the observation of gravitational waves by the Advanced LIGO detectors from a binary black hole merger is an event of tremendous scientific significance. A century ago, Einstein developed general relativity and predicted the existence of gravitational waves. This first direct detection of gravitational waves, the so-called “GW150914” event, is a confirmation of Einstein’s theory and is the first direct observation of a pair of black holes merging to form a single black hole. The observation of GW150914, and future observations of binary black hole mergers, will provide new insights about massive black holes in the relatively nearby part of our Universe.

    GW150914 will not be the only event of its type in the Universe. It can be expected that, on average, binary black hole mergers occur at some rate. When these mergers happen within a couple of billion light-years from the Earth, they will likely be directly observed by Advanced LIGO (and soon to come, Advanced Virgo, and ESA eLISA). Events that are further than this will just appear as random noise in the gravitational-wave detectors (like static on an old-fashioned TV), too small to be individually directly measured. However, it will be possible to observe the sum of binary black hole mergers that have happened throughout the history of our observable Universe.

    What is a gravitational-wave background?
    Gravitational waves are ripples in spacetime predicted by Einstein’s theory of general relativity. Gravitational waves are produced by accelerating objects of any size, including us humans. Most of these waves, however, are far too weak to experimentally detect. In general, we can only hope to observe gravitational waves produced by the most massive objects moving close to the speed of light, such as the binary black holes that produced GW150914.

    For every nearby, loud event like GW150914, there are many more that are too far away to be individually detected by Advanced LIGO. The gravitational waves from these distant binary black holes instead combine to create a relatively quiet “popcorn” background of gravitational waves. As a pair of black holes merges, it produces a short burst of gravitational waves lasting just a few tenths of a second. These mostly-quiet individual bursts are separated in time, and arrive at Earth at an average rate of about one every 15 minutes. Their exact arrival times, though, are randomly distributed, just like the random popping of individual kernels of popcorn.

    A popcorn background is an example of a broader category of gravitational-wave signal called a stochastic background. In general, stochastic backgrounds are formed by the combination of many unresolvable sources. Unresolvable sources are those which we cannot distinguish individually, either because they are too quiet (as in the case of a popcorn background described above) or because there are simply too many occurring at once. Detecting a stochastic background is something like listening to voices in a crowded room. Aside from the loudest people and those standing nearest to you, you can hear the remaining conversations blend together into a continuous hum.

    What can it tell us?
    Gravitational waves are expected to have been created throughout the history of the Universe. Depending on when they were produced, gravitational-wave backgrounds can be classified into two basic categories: cosmological and astrophysical. Cosmological backgrounds are predicted to have been produced by sources that existed in the very early Universe just a few seconds after the Big Bang, while astrophysical backgrounds are predicted to have been produced by systems of massive stars such as the neutron stars and black holes that we see today. Most likely, contributions to the gravitational-wave background from astrophysical sources will dominate cosmological ones. The gravitational-wave signal produced by a population of binary black holes like GW150914 is an example of an astrophysical background.

    The strength of the gravitational-wave background at different frequencies strongly depends on the type of sources that produce them. Thus, depending on the type of gravitational-wave background we detect, we may learn about the state of the Universe just a few moments after the Big Bang or how the Universe is evolving in more recent times. In addition, looking at whether the signal is stronger from certain directions on the sky or is uniformly spread out will give us information about the distribution of the sources that produced the background.

    What does GW150914 mean for a gravitational-wave background? Why is this interesting?
    GW150914 was a single event. Its gravitational waves were from the merger of two black holes, having masses of about 29 times and 36 times the mass of the Sun, forming a single black hole with a mass of about 62 times the Sun’s mass. The large component masses of the black holes making up GW150914 suggest that the unresolved popcorn signal from the population of binary black holes is probably stronger than most astrophysicists originally thought. This means we have a better chance of measuring this background with the Advanced LIGO and Virgo detectors. We will have to analyze the data for several years, but it may be possible to eventually measure the signal.

    How do we detect these gravitational waves?
    Although the individual signals from the binary black hole mergers have a characteristic shape, the signals from distant sources will be too weak to be individually detected and the arrival times of the popcorn-like bursts will be random. This means that the standard searches that look for single events like GW150914 won’t work for detecting the relatively quiet popcorn signal from the population of binary black hole mergers throughout the Universe. So we need to take a different approach (described below) to detect the waves from these unresolvable sources.

    It is hard to search for a weak random signal using data from a single detector because the detector noise itself is also random. So instead we compare (“correlate”) data from pairs of detectors, e.g., the two LIGO detectors in Hanford, WA and Livingston, LA. The random gravitational-wave signal will be the same (“correlated”) in both detectors, while the detector noise will not (since the detectors are widely separated and most noise sources due to the environment are local to the detectors). Thus we can use this similarity (“correlation”) to distinguish the gravitational-wave signal from unwanted detector noise.

    Moreover, by performing this correlation over the whole duration of the run (which could be months or years), we build up the signal relative to the noise by including the contribution of the events that occur (on average) once every 15 minutes. The more data we have to analyze, the better it is for this type of search.

    Estimating the gravitational-wave background based on what we’ve learned from GW150914
    A number of factors contribute to how many binary black hole systems will form in the Universe. An important long-term research question will be to try and describe how systems like GW150914 were created. For example, maybe the two original black holes in GW150914 evolved from a binary star system, where the two stars orbiting one another were very massive. Or perhaps the system was created in a globular cluster (a group of stars tightly bound together by gravity) where one could imagine many interactions taking place that would make initially small black holes evolve into larger ones. The most massive stars are short-lived and often produce black holes upon their death, so knowing the birth rate of massive stars is important. Star formation rates depend on the amount of matter present, and its constituents; was there just hydrogen and helium present when the star was formed, or were there other elements as well? Also, how long did the two black holes take to get close enough to collide? All of these ingredients contribute to the different binary black hole formation models that we considered.

    If we detect a stochastic gravitational-wave background in the future, we will not be able to distinguish between different models describing how these binary black hole systems were created. We will, however, be able to contribute to understanding how often these mergers happen in the far away Universe. Future measurements of individual mergering black holes will provide a better estimate of how often these types of events take place in the nearby Universe and more information on the masses of the black holes. Combining what we learn from a stochastic background with measurements from individual events may help distinguish between different formation pathways for binary black holes.

    Implications for the future
    The GW150914 event suggests that merger rates and masses of binary black holes are on the high end of the range of earlier predictions. This means that a gravitational-wave background due to merging black holes is expected to be larger as well. There are sizable uncertainties associated with the strength of this background, but detecting it may be within reach of the advanced detectors at their peak sensitivity. Looking to the future, the next generation of gravitational-wave detectors might be able combine measurements of a gravitational-wave background with measurements of individual black hole mergers to distinguish how black holes may come to orbit one another.

    Glossary

    Astrophysical background A stochastic background of gravitational waves produced by sources such as neutron stars and black holes.
    Black hole A region of space-time caused by an extremely compact mass where the gravity is so intense it prevents anything, including light, from leaving.
    Correlation The amount of similarity between two sets of data. For example, the comparison of data from pairs of gravitational-wave detectors in order to search for weak signals (like a stochastic background) that are shared (“correlated”) between the two instruments.
    Cosmological background A stochastic background of gravitational waves produced by sources such as those in the very early Universe in the instant after the Big Bang.
    Globular cluster A very dense group of stars bound together by gravity.
    Neutron star An extremely dense object which remains after the collapse of a massive star.
    Popcorn background The combination effects of bursts of gravitational waves from all binary black holes too distant to be directly observed. These bursts arrive at Earth at random times, like the popping of individual kernels of corn.
    Spacetime An interwoven continuum of space and time.
    Stochastic background A gravitational-wave signal formed from the combination of many individually unresolvable sources. Sources are unresolvable if they are too weak to be directly observed or if too many overlap at once, like conversations in a loud, crowded room.
    Stochastic Randomly determined; having a random pattern that may be analyzed statistically but may not be predicted precisely.

    Read more:

    Freely readable preprint of the publication describing the analysis
    Data used for this analysis
    Advanced LIGO
    Advanced Virgo

    See the full article here .

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    About the LSC

    The LIGO Scientific Collaboration (LSC) is a group of scientists seeking to make the first direct detection of gravitational waves, use them to explore the fundamental physics of gravity, and develop the emerging field of gravitational wave science as a tool of astronomical discovery. The LSC works toward this goal through research on, and development of techniques for, gravitational wave detection; and the development, commissioning and exploitation of gravitational wave detectors.

    The LSC carries out the science of the LIGO Observatories, located in Hanford, Washington and Livingston, Louisiana as well as that of the GEO600 detector in Hannover, Germany. Our collaboration is organized around three general areas of research: analysis of LIGO and GEO data searching for gravitational waves from astrophysical sources, detector operations and characterization, and development of future large scale gravitational wave detectors.

    Founded in 1997, the LSC is currently made up of more than 1000 scientists from dozens of institutions and 15 countries worldwide. A list of the participating universities.

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    VIRGO Gravitational Wave interferometer, near Pisa, Italy
    VIRGO Gravitational Wave interferometer, near Pisa, Italy

     
  • richardmitnick 9:17 am on May 29, 2017 Permalink | Reply
    Tags: , , , , , Doppler shifts, , , Veloce spectrograph   

    From AAO: “A new laser at the AAT!” 

    AAO Australian Astronomical Observatory

    Australian Astronomical Observatory

    6

    A new laser at the AAT! Last week we took delivery of the new laser frequency comb for the Veloce spectrograph (https://newt.phys.unsw.edu.au/~cgt/Veloce/Veloce.html), which will replace the AAT’s venerable UCLES instrument early next year. The laser frequency comb will provide Veloce with an ultra-stable calibration source, enabling it to separate tiny Doppler shifts in the wavelength of light from a star caused by orbiting exoplanets from slight drifts in the instrument itself. With this Veloce will be able to measure Doppler shifts of less than 1 part in 300 000 000, equivalent to measuring the motion of a star to a precision of less than 3.6 kilometres per hour!

    1

    2

    3

    4

    ^AJH

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    AAO Anglo Australian Telescope Exterior
    AAO Anglo Australian Telescope Interior
    Anglo-Australian telescope

    The Australian Astronomical Observatory, a division of the Department of Industry, Innovation and Science, operates the Anglo-Australian and UK Schmidt telescopes on behalf of the astronomical community of Australia. To this end the Observatory is part of and is funded by the Australian Government. Its function is to provide world-class observing facilities for Australian optical astronomers.

     
  • richardmitnick 9:02 am on May 29, 2017 Permalink | Reply
    Tags: , , ,   

    From Nature: “DNA’s secret weapon against knots and tangles” 

    Nature Mag
    Nature

    19 April 2017 [Another hidden treasure comes to social media.]
    Elie Dolgin

    1
    DNA loops help to keep local regions of the genome together. M. Imakaev/G. Fudenberg/N. Naumova/J. Dekker/L. Mirny

    Leonid Mirny swivels in his office chair and grabs the power cord for his laptop. He practically bounces in his seat as he threads the cable through his fingers, creating a doughnut-sized loop. “It’s a dynamic process of motors constantly extruding loops!” says Mirny, a biophysicist here at the Massachusetts Institute of Technology in Cambridge.

    Mirny’s excitement isn’t about keeping computer accessories orderly. Rather, he’s talking about a central organizing principle of the genome — how roughly 2 metres of DNA can be squeezed into nearly every cell of the human body without getting tangled up like last year’s Christmas lights.

    He argues that DNA is constantly being slipped through ring-like motor proteins to make loops. This process, called loop extrusion, helps to keep local regions of DNA together, disentangling them from other parts of the genome and even giving shape and structure to the chromosomes.

    Scientists have bandied about similar hypotheses for decades, but Mirny’s model, and a similar one championed by Erez Lieberman Aiden, a geneticist at Baylor College of Medicine in Houston, Texas, add a new level of molecular detail at a time of explosive growth for research into the 3D structure of the genome. The models neatly explain the data flowing from high-profile projects on how different parts of the genome interact physically — which is why they’ve garnered so much attention.

    But these simple explanations are not without controversy. Although it has become increasingly clear that genome looping regulates gene expression, possibly contributing to cell development and diseases such as cancer, the predictions of the models go beyond what anyone has ever seen experimentally.

    For one thing, the identity of the molecular machine that forms the loops remains a mystery. If the leading protein candidate acted like a motor, as Mirny proposes, it would guzzle energy faster than it has ever been seen to do. “As a physicist friend of mine tells me, ‘This is kind of the Higgs boson of your field’,” says Mirny; it explains one of the deepest mysteries of genome biology, but could take years to prove.

    And although Mirny’s model is extremely similar to Lieberman Aiden’s — and the differences esoteric — sorting out which is right is more than a matter of tying up loose ends. If Mirny is correct, “it’s a complete revolution in DNA enzymology”, says Kim Nasmyth, a leading chromosome researcher at the University of Oxford, UK. What’s actually powering the loop formation, he adds, “has got to be the biggest problem in genome biology right now”.

    Loop back

    Geneticists have known for more than three decades that the genome forms loops, bringing regulatory elements into close proximity with genes that they control. But it was unclear how these loops formed.

    Several researchers have independently put forward versions of loop extrusion over the years. The first was Arthur Riggs, a geneticist at the Beckman Research Institute of City of Hope in Duarte, California, who first proposed what he called “DNA reeling” in an overlooked 1990 report[1]. Yet it’s Nasmyth who is most commonly credited with originating the concept.

    As he tells it, the idea came to him in 2000, after a day spent mountain climbing in the Italian Alps. He and his colleagues had recently discovered the ring-like shape of cohesin[2], a protein complex best known for helping to separate copies of chromosomes during cell division. As Nasmyth fiddled with his climbing gear, it dawned on him that chromosomes might be actively threaded through cohesin, or the related complex condensin, in much the same way as the ropes looped through his carabiners. “It appeared to explain everything,” he says.

    Nasmyth described the idea in a few paragraphs in a massive, 73-page review article [3]. “Nobody took notice whatsoever,” he says — not even John Marko, a biophysicist at Northwestern University in Evanston, Illinois, who more than a decade later developed a mathematical model that complemented Nasmyth’s verbal argument[4].

    Mirny joined this loop-modelling club around five years ago. He wanted to explain data sets compiled by biologist Job Dekker, a frequent collaborator at the University of Massachusetts Medical School in Worcester. Dekker had been looking at physical interactions between different spots on chromosomes using a technique called Hi-C, in which scientists sequence bits of DNA that are close to one another and produce a map of each chromosome, usually depicted as a fractal-like chessboard. The darkest squares along the main diagonal represent spots of closest interaction.

    The Hi-C snapshots that Dekker and his collaborators had taken revealed distinct compartmentalized loops, with interactions happening in discrete blocks of DNA between 200,000 and 1 million letters long[5].

    These ‘topologically associating domains’, or TADs, are a bit like the carriages on a crowded train. People can move about and bump into each other in the same carriage, but they can’t interact with passengers in adjacent carriages unless they slip between the end doors. The human genome may be 3 billion nucleotides long, but most interactions happen locally, within TADs.

    Mirny and his team had been labouring for more than a year to explain TAD formation using computer simulations. Then, as luck would have it, Mirny happened to attend a conference at which Marko spoke about his then-unpublished model of loop extrusion. (Marko coined the term, which remains in use today.) It was the missing piece of Mirny’s puzzle. The researchers gave loop extrusion a try, and it worked. The physical act of forming the loops kept the local domains well organized. The model reproduced many of the finer-scale features of the Hi-C maps.

    When Mirny and his colleagues posted their finished manuscript on the bioRxiv preprint server in August 2015, they were careful to describe the model in terms of a generic “loop-extruding factor”. But the paper didn’t shy away from speculating as to its identity: cohesin was the driving force behind the looping process for cells not in the middle of dividing, when chromosomes are loosely packed[6]. Condensin, they argued in a later paper, served this role during cell division, when the chromosomes are tightly wound[7].

    A key clue was the protein CTCF, which was known to interact with cohesin at the base of each loop of uncondensed chromosomes. For a long time, researchers had assumed that loops form on DNA when these CTCF proteins bump into one another at random and lock together. But if any two CTCF proteins could pair, why did loops form only locally, and not between distant sites?

    Mirny’s model assumes that CTCFs act as stop signs for cohesin. If cohesin stops extruding DNA only when it hits CTCFs on each side of a growing loop, it will naturally bring the proteins together.

    But singling out cohesin was “a big leap of faith”, says biophysicist Geoff Fudenberg, who did his PhD in Mirny’s lab and is now at the University of California, San Francisco. “No one has seen these motors doing these things in living cells or even in vitro,” he says. “But we see all of these different features of the data that line up and can be unified under this principle.”

    Experiments had shown, for example, that reducing the amount of cohesin in a cell results in the formation of fewer loops[8]. Overactive cohesin creates so many loops that chromosomes smush up into structures that resemble tiny worms[9].

    The authors of these studies had trouble making sense of their results. Then came Mirny’s paper on bioRxiv. It was “the first time that a preprint has really changed the way people were thinking about stuff in this field”, says Matthias Merkenschlager, a cell biologist at the MRC London Institute of Medical Sciences. (Mirny’s team eventually published the work in May 2016, in Cell Reports [6].)

    Multiple discovery?

    Lieberman Aiden says that the idea of loop extrusion first dawned on him during a conference call in March 2015. He and his former mentor, geneticist Eric Lander of the Broad Institute in Cambridge, Massachusetts, had published some of the most detailed, high-resolution Hi-C maps of the human genome available at the time[10].

    During his conference call, Lieberman Aiden was trying to explain a curious phenomenon in his data. Almost all the CTCF landing sites that anchored loops had the same orientation. What he realized was that CTCF, as a stop sign for extrusion, had inherent directionality. And just as motorists race through intersections with stop signs facing away from them, so a loop-extruding factor goes through CTCF sites unless the stop sign is facing the right way.

    His lab tested the model by systematically deleting and flipping CTCF-binding sites, and remapping the chromosomes with Hi-C. Time and again, the data fitted the model. The team sent its paper for review in July 2015 and published the findings three months later [11].

    Mirny’s August 2015 bioRxiv paper didn’t have the same level of experimental validation, but it did include computer simulations to explain the directional bias of CTCF. In fact, both models make essentially the same predictions, leading some onlookers to speculate on whether Mirny seeded the idea. Lieberman Aiden insists that he came up with his model independently. “We submitted our paper before I ever saw their manuscript,” he says.

    There are some tiny differences. The cartoons Mirny uses to describe his model seem to suggest that one cohesin ring does the extruding, whereas Lieberman Aiden’s contains two rings, connected like a pair of handcuffs (see ‘The taming of the tangles’). Suzana Hadjur, a cell biologist at University College London, calls this mechanistic nuance “absolutely fundamental” to determining cohesin’s role in the extrusion process.

    2
    Nik Spencer/Nature

    Neither Lieberman Aiden nor Mirny say they have a strong opinion on whether the system uses one ring or two, but they do differ on cohesin’s central contribution to loop formation. Mirny maintains that the protein is the power source for looping, whereas Lieberman Aiden summarily dismisses this idea. Cohesin “is a big doughnut”, he says. It doesn’t do that much. “It can open and close, but we are very, very confident that cohesin itself is not a motor.”

    Instead, he suspects that some other factor is pushing cohesin around, and many in the field agree. Claire Wyman, a molecular biophysicist at Erasmus University Medical Centre in Rotterdam, the Netherlands, points out that cohesin is only known to consume small amounts of energy for clasping and releasing DNA, so it’s a stretch to think of it motoring along the chromosome at the speeds required for Mirny’s model to work. “I’m willing to concede that it’s possible,” she says. “But the Magic 8-Ball would say that, ‘All signs point to no’.”

    One group of proteins that might be doing the pushing is the RNA polymerases, the enzymes that create RNA from a DNA template. In a study online in Nature this week[12], Jan-Michael Peters, a chromosome biologist at the Research Institute of Molecular Pathology in Vienna, and his colleagues show that RNA polymerases can move cohesin over long distances on the genome as they transcribe genes into RNA. “RNA polymerases are one type of motor that could contribute to loop extrusion,” Peters says. But, he adds, the data indicate that it cannot be the only force at play.

    Frank Uhlmann, a biochemist at the Francis Crick Institute in London, offers an alternative that doesn’t require a motor protein at all. In his view, a cohesin complex might slide along DNA randomly until it hits a CTCF site and creates a loop. This model requires only nearby strands of DNA to interact randomly — which is much more probable, Uhlmann says. “We do not need to make any assumptions about activities that we don’t have experimental evidence for.”

    Researchers are trying to gather experimental evidence for one model or another. At the Lawrence Livermore National Laboratory in California, for example, biophysicist Aleksandr Noy is attempting to watch loop extrusion in action in a test tube. He throws in just three ingredients: DNA, some ATP to provide energy, and the bacterial equivalent of cohesin and condensin, a protein complex known as SMC.

    “We see evidence of DNA being compacted into these kinds of flowers with loops,” says Noy, who is collaborating with Mirny on the project. That suggests that SMC — and by extension cohesin — might have a motor function. But then again, it might not. “The truth is that we just don’t know at this point,” Noy says.

    Bacterial battery

    The experiment that perhaps comes the closest to showing cohesin acting as a motor was published in February[13]. David Rudner, a bacterial cell biologist at Harvard Medical School in Boston, Massachusetts, and his colleagues made time-lapse Hi-C maps of the bacterium Bacillus subtilis that reveal SMC zipping along the chromosome and creating a loop at a rate of more than 50,000 DNA letters per minute. This tempo is on par with what researchers estimate would be necessary for Mirny’s model to work in human cells as well.

    Rudner hasn’t yet proved that SMC uses ATP to make that happen. But, he says, he’s close — and he would be “shocked” if cohesin worked differently in human cells.

    For now, the debate rages about what cohesin is, or is not, doing inside the cell — and many researchers, including Doug Koshland, a cell biologist at the University of California, Berkeley, insist that a healthy dose of scepticism is still warranted when it comes to Mirny’s idea. “I am worried that the simplicity and elegance of the loop-extrusion model is already filling textbooks, coronated long before its time,” he says.

    And although it may seem an academic dispute among specialists, Mirny notes that if it his model is correct, it will have real-world implications. In cancer, for instance, cohesin is frequently mutated and CTCF sites altered. Defective versions of cohesin have also been implicated in several rare human developmental disorders. If the loop-extruding process is to blame, says Mirny, then perhaps a better understanding of the motor could help fix the problem.

    But his main interest remains more fundamental. He just wants to understand why DNA is configured in the way it is. And although his model assumes a lot of things about cohesin, Mirny says, “The problem is that I don’t know any other way to explain the formation of these loops.”

    References
    See the full article for 13 references with links.

    See the full article here .

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 8:31 am on May 29, 2017 Permalink | Reply
    Tags: , , , Harnessing the energy generated when freshwater meets saltwater, ,   

    From Penn State via phys.org: “Harnessing the energy generated when freshwater meets saltwater” 

    Penn State Bloc

    Pennsylvania State University

    phys.org

    May 29, 2017
    Jennifer Matthews

    2
    Credit: Pennsylvania State University

    Penn State researchers have created a new hybrid technology that produces unprecedented amounts of electrical power where seawater and freshwater combine at the coast.

    “The goal of this technology is to generate electricity from where the rivers meet the ocean,” said Christopher Gorski, assistant professor in environmental engineering at Penn State. “It’s based on the difference in the salt concentrations between the two water sources.”

    That difference in salt concentration has the potential to generate enough energy to meet up to 40 percent of global electricity demands. Though methods currently exist to capture this energy, the two most successful methods, pressure retarded osmosis (PRO) and reverse electrodialysis (RED), have thus far fallen short.

    PRO, the most common system, selectively allows water to transport through a semi-permeable membrane, while rejecting salt. The osmotic pressure created from this process is then converted into energy by turning turbines.

    “PRO is so far the best technology in terms of how much energy you can get out,” Gorski said. “But the main problem with PRO is that the membranes that transport the water through foul, meaning that bacteria grows on them or particles get stuck on their surfaces, and they no longer transport water through them.”

    This occurs because the holes in the membranes are incredibly small, so they become blocked easily. In addition, PRO doesn’t have the ability to withstand the necessary pressures of super salty waters.

    The second technology, RED, uses an electrochemical gradient to develop voltages across ion-exchange membranes.

    “Ion exchange membranes only allow either positively charged ions to move through them or negatively charged ions,” Gorski explained. “So only the dissolved salt is going through, and not the water itself.”

    Here, the energy is created when chloride or sodium ions are kept from crossing ion-exchange membranes as a result of selective ion transport. Ion-exchange membranes don’t require water to flow through them, so they don’t foul as easily as the membranes used in PRO; however, the problem with RED is that it doesn’t have the ability to produce large amounts of power.

    3
    Photograph of the concentration flow cell. Two plates clamp the cell together, which contains two narrow channels fed with either synthetic freshwater or seawater through the plastic lines. Credit: Pennsylvania State University

    A third technology, capacitive mixing (CapMix), is a relatively new method also being explored. CapMix is an electrode-based technology that captures energy from the voltage that develops when two identical electrodes are sequentially exposed to two different kinds of water with varying salt concentrations, such as freshwater and seawater. Like RED, the problem with CapMix is that it’s not able to yield enough power to be viable.

    Gorski, along with Bruce Logan, Evan Pugh Professor and the Stan and Flora Kappe Professor of Environmental Engineering, and Taeyoung Kim, post-doctoral scholar in environmental engineering, may have found a solution to these problems. The researchers have combined both the RED and CapMix technologies in an electrochemical flow cell.

    “By combining the two methods, they end up giving you a lot more energy,” Gorski said.

    The team constructed a custom-built flow cell in which two channels were separated by an anion-exchange membrane. A copper hexacyanoferrate electrode was then placed in each channel, and graphite foil was used as a current collector. The cell was then sealed using two end plates with bolts and nuts. Once built, one channel was fed with synthetic seawater, while the other channel was fed with synthetic freshwater. Periodically switching the water’s flow paths allowed the cell to recharge and further produce power. From there, they examined how the cutoff voltage used for switching flow paths, external resistance and salt concentrations influenced peak and average power production.

    “There are two things going on here that make it work,” said Gorski. “The first is you have the salt going to the electrodes. The second is you have the chloride transferring across the membrane. Since both of these processes generate a voltage, you end up developing a combined voltage at the electrodes and across the membrane.”

    To determine the gained voltage of the flow cell depending on the type of membrane used and salinity difference, the team recorded open-circuit cell voltages while feeding two solutions at 15 milliliters per minute. Through this method, they identified that stacking multiple cells did influence electricity production. At 12.6 watts per square meter, this technology leads to peak power densities that are unprecedentedly high compared to previously reported RED (2.9 watts per square meter), and on par with the maximum calculated values for PRO (9.2 watts per square meter), but without the fouling problems.

    “What we’ve shown is that we can bring that power density up to what people have reported for pressure retarded osmosis and to a value much higher that what has been reported if you use these two processes alone,” Gorski said.

    Though the results are promising, the researchers want to do more research on the stability of the electrodes over time and want to know how other elements in seawater— like magnesium and sulfate— might affect the performance of the cell.

    “Pursuing renewable energy sources is important,” Gorski said. “If we can do carbon neutral energy, we should.”

    No science paper referenced.

    See the full article here .

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    Penn State Campus

    WHAT WE DO BEST

    We teach students that the real measure of success is what you do to improve the lives of others, and they learn to be hard-working leaders with a global perspective. We conduct research to improve lives. We add millions to the economy through projects in our state and beyond. We help communities by sharing our faculty expertise and research.

    Penn State lives close by no matter where you are. Our campuses are located from one side of Pennsylvania to the other. Through Penn State World Campus, students can take courses and work toward degrees online from anywhere on the globe that has Internet service.

    We support students in many ways, including advising and counseling services for school and life; diversity and inclusion services; social media sites; safety services; and emergency assistance.

    Our network of more than a half-million alumni is accessible to students when they want advice and to learn about job networking and mentor opportunities as well as what to expect in the future. Through our alumni, Penn State lives all over the world.

    The best part of Penn State is our people. Our students, faculty, staff, alumni, and friends in communities near our campuses and across the globe are dedicated to education and fostering a diverse and inclusive environment.

     
  • richardmitnick 8:16 am on May 29, 2017 Permalink | Reply
    Tags: , , Speed of animal evolution enhanced by cooperative behaviour,   

    From Cambridge: “Speed of animal evolution enhanced by cooperative behaviour” We could all learn from that 

    U Cambridge bloc

    Cambridge University

    26 May 2017
    Stuart Roberts
    Stuart.J.Roberts@admin.cam.ac.uk

    1
    A study by scientists from the University of Cambridge has revealed how cooperative behaviour between insect family members changes how rapidly body size evolves – with the speed of evolution increasing when individual animals help one another.

    Cooperative behaviour is a key part of animal family life: parents help offspring by supplying them with food, and siblings can also work together to acquire food. The Cambridge study, published today in Nature Ecology and Evolution, looked at the burying beetle – unusual in the insect world as the parents feed their offspring.

    Larvae in small broods are well supplied with food by their parents and grow large. In the parents’ absence, larvae can also help each other to forage for food. However, in the absence of their parents, small broods of larvae are less effective at helping each other and can never grow as big.

    “For our study, we played the role of natural selection. In some experimental beetle populations, we chose only the largest beetles to breed at each generation and in some we chose only the smallest beetles,” said Benjamin Jarrett from the Department of Zoology at the University of Cambridge, who led the study.

    “Crucially, we also changed the social conditions within beetle families. In some populations, we allowed parents to help their offspring, but in other populations we removed the parents, and larvae had to help each other. We found that the social conditions made a big difference to how quickly beetle body size evolves over generations.”

    Beetles only evolved a larger body size when parents were present to help rear their young. In stark contrast, smaller body size only evolved when beetle parents were removed, and there were too few larvae to help each other.

    The experiment helps explain how different species of burying beetle might have evolved their different body sizes. In general, larger species of beetle have more diligent parents than smaller species.

    Burying beetles use the dead body of a small animal, like a mouse or bird, for reproduction. The parents shave and bury the carcass, to make it into an edible nest for their larvae. The larvae can feed themselves on the carrion, but the parent beetles also regurgitate partly digested food to them. The species used in this study has quite variable levels of parental care: occasionally larvae have to fend for themselves on the carcass because they have been abandoned by their parents.

    “Previous work has focused on the puzzle of how cooperative behaviour evolves, because natural selection seems to favour animals that are selfish,” said Professor Rebecca Kilner, who is senior author of this paper. “We have shown that what happens next, in evolutionary terms, is just as interesting. Once cooperation has evolved, it can change the way in which evolution then unfolds.”

    The researchers now hope to uses experimental evolution to understand what happens across many generations when changing the extent of parental care.

    “We can remove parents from caring for their offspring in one generation, and we do this to their offspring too, and their grandoffspring, and so on,” added Jarrett. “We currently have populations of beetles that have not had parents looking after them as they grow up for 25 generations.

    “What this does is change what evolution is working on. Natural selection is usually acting on the combination of parents and offspring, and now, by removing parents, we have changed the traits on which evolution acts.”

    The paper Cooperative interactions within the family enhance the capacity for evolutionary change in body size, published in Nature Ecology and Evolution, can be found here: http://dx.doi.org/10.1038/241559-017-0178

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
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