# Sudoku and Velocity Fields...

Topics: Materials Science, Probability, Radiation, X-rays

To see what happens inside a pile of sand or another volume of granular material, researchers rely either on deformation observations at the surface, which don’t always reflect any internal flows, or on simulations. Several existing techniques can image interior flows, but they each have one or more disadvantages, such as limited spatial and temporal resolutions, high costs, and invasiveness. A new technique, developed by James Baker, Itai Einav, and their colleagues at the University of Sydney, overcame those hurdles by using sets of two-dimensional x-ray radiographs to uncover the three-dimensional velocity field inside a volume of opaque grains.

X rays were fired from three orthogonal locations through a container of opaque grains that were being sheared from below by a conveyor belt, as shown in the diagram above. By spatially correlating successive radiographs, the researchers extracted the probability density functions (PDFs) of the two displacement components orthogonal to the x-ray direction for each grid cell. Each PDF was then sampled evenly to generate an unsorted array of the different displacements through the beam direction.

By combining the PDF results orthogonal to each other and solving a Sudoku-style puzzle, the researchers were able to reconstruct the 3D velocity field shown from 2D projections. As in Sudoku, the displacement values that should be placed in each row and column are known from the two sets of PDFs, but how to arrange those displacements in space defines the puzzle. Unlike in Sudoku, though, there is no unique solution.

X-ray correlations assemble a complete velocity field, Alex Lopatka, Physics Today

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## Blog Posts

### Initial posting

Posted by Kwesi Adebisi on January 15, 2019 at 9:40am

I would give an intricate, wordy introduction, but there are some hinderances. I am currently realm-building for a debut series, but life has a way of taking priority. One day, I will have the availability I need. My next one will be more detailed, rest assured.

### Disaster Hypocrisy...

Posted by Reginald L. Goodwin on January 15, 2019 at 5:30am

 Credit: Karl Spencer Getty Images

Topics: Climate Change, Global Warming, Politics, Research

Mexico won’t pay for President Trump’s border wall. But Northern Californians might.

Many of…
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### 3D Topological Insulators...

Posted by Reginald L. Goodwin on January 14, 2019 at 5:30am

 Courtesy: H. Chen

Topics: Laser, Optical Physics, Photonics, Materials Science, Nanotechnology, Quantum Mechanics

Reference: Topological Insulators, then the rest of the post.…

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### Post Apocalypse...

Posted by Reginald L. Goodwin on January 11, 2019 at 5:30am

 Nuff said.

Topics: Civics, Civil Rights, Existentialism, Human Rights, Politics

Donald J. Trump is a a carefully-crafted public fiction. I have said this for years, and stand by that assertion. A headline from Newsweek: "…
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### ONYXCON SANKOFA 2019 - Saturday and Sunday February 16-17

Posted by Jarvis Sheffield - Admin on January 10, 2019 at 8:49am

ONYXCON returns to WOLF CREEK LIBRARY for another celebration of the HISTORY of the African Diaspora in Popular Arts! JOIN US Saturday and Sunday FEBRUARY 16-17 for family fun and EDUTAINMENT! VENDING NOW AVAILABLE! APPLY via ONYXCON@gmail.com

### Hobbled Hubble...

Posted by Reginald L. Goodwin on January 10, 2019 at 5:30am

 The Hubble telescope launched in 1990. Credit: NASA

Topics: Astronomy, Astrophysics, NASA, Politics, Research

Yet another casualty: science. The NSF, NOAA and other related sites are…
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### Earth's AT-ATs...

Posted by Reginald L. Goodwin on January 9, 2019 at 5:30am

Topics: Green Energy, Green Tech, Mechanical Engineering, Robotics, Star Wars

Ironically, I drive a Hyundai Santa Fe (2013). But I'm satisfied with its performance, so I don't think I'll be "trading up" to this one. Plus, it's designed primarily for first responders.…

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### Nano Zappers...

Posted by Reginald L. Goodwin on January 8, 2019 at 5:30am

Topics: Biology, Cancer, Electromagnetic Radiation, Green Energy, Nanotechnology, Research

One potentially valuable way to attack cancer cells is to zap them with low-intensity alternating current. This interferes with the flow of calcium and potassium ions in and out of the cells, a process so important that disrupting it ultimately kills them.

But there is a problem with this approach:…
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### Multi Messenger Astronomy...

Posted by Reginald L. Goodwin on January 7, 2019 at 5:30am

 Figure 1: On 17 August 2017 LIGO detected gravitational waves from a neutron-star collision. Within 12 hours observatories had identified the source of the event GW170817 within the galaxy NGC 4993 – shown in this Hubble Space Telescope image – and located the associated radioactive emissions, or “kilonova”. Hubble observed that flare of light fade over the course of six days, as shown in these observations taken on 22, 26 and 28 August (insets). (Courtesy: NASA, ESA; A Levan (University of Warwick), N Tanvir (University of Leicester), A…
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### Intelligent Collectors encouraged!

Posted by Turtel Onli on January 2, 2019 at 7:32am

The fact that most indie Black Age publishers produce limited editions or small press runs insures the collector will likely have a rare item to treasure. Future speculative investors, auctions and collectors, once its time has come, will pay dividends to acquire items from this extended important era in this industry. Seeing "Black" as investment value or prestige is growing beyond the realm of that which comes from the mainstream. Most will be left saying...."I had those Black Age books...I didn't ever think much of them. Damn!"

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## THE UNDERGROUND BY ROXANNE BLAND

Life as alpha of a werewolf pack is anything but predictable. But even Parker Berenson is surprised by the latest twist: he’s fallen in love with a space alien. Problem is, he suspects Melera, his sexy new flame, might be the serial killer terrorizing Seattle. Or maybe she isn’t. After all, just because she’s an interstellar assassin doesn’t mean she’s guilty.

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