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John Murrin
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A New Wave of Quantum Computers: D-Wave to Ship a 2,000-Qubit Quantum Computer by 2017 http://buff.ly/2dlRiat
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COLUMBUS, OH—Going about his daily routine without any knowledge of what would transpire in the near future, local black man Richard Phillips was said to be blissfully unaware Thursday that his name would be a social media hashtag by the end of the week.
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After Chicago police officers Shannon Spalding and Danny Echeverria filed a whistleblower lawsuit, retaliation against them only intensified.
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13 universities adopt MicroMasters as a way to turn online classes into a master's degree.

#highered #continuingeducation #learning #MIT
And then? Apply—ahead of the pack—if you feel like it. It’s the ‘MicroMasters,’ and here’s how it works.
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With new neural network architectures popping up every now and then, it’s hard to keep track of them all. Knowing all the abbreviations being thrown around (DCIGN, BiLSTM, DCGAN, anyone?) can be a bit overwhelming at first. So I decided to compose a cheat sheet containing many of those architectures. Most of these are neural networks, some are completely …
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Gordian (un)knots

The Gordian knot was a famously intricate knot attached to a sacred ox cart in the ancient city of Gordium, near Ankara in modern-day Turkey.

In 333 BC, Alexander the Great attempted to untie the knot, but was unable to find the ends of the knot in order to do so. Instead, he is said to have undone the knot using what is now called the Alexandrian solution, which was to cut the knot in half with his sword.

Although there is good historical evidence that Alexander undid the Gordian knot, sources differ on how he accomplished this. According to some accounts, a more plausible theory is that he undid the knot by first removing the pin around which the knot was tied. This might have exposed the two ends of the knot, making it much easier to untie.

Another possibility is that the Gordian knot did not have ends, and was a knotted loop instead of a knotted open piece of rope (or, in this case, bark). In other words, the Gordian knot might have been what mathematicians refer to as an unknot.

More precisely, an unknot is a (possibly knotted) closed loop that can be disentangled (i.e., continuously deformed) into a closed loop with no knot in it, without cutting the knot in the process. The branch of mathematics that deals with concepts like these is known as knot theory. Knot theory can cast light on scientific applications, for example the ways in which long organic molecules such as DNA can form tight coils.

The animation shows a good example of an unknot. However, the knot in the picture is made out of a very stretchy and almost frictionless material, unlike any material that a physical knot would likely be made out of.

What this means is that there may exist “Gordian” unknots which can be disentangled to the unknot in theory, but which cannot be disentangled in practice because of physical limitations of the material. Cutting the knot, or altering it in other ways (for example by soaking it) is considered cheating. The unknot in the animation is thought to be an example of such a Gordian unknot, but it seems that nobody has yet proved this rigorously.

Relevant links
Wikipedia on the Gordian knot: http://en.wikipedia.org/wiki/Gordian_Knot

Wikipedia on the unknot: http://en.wikipedia.org/wiki/Unknot

Gordian unknots, a paper from 2001 by P. Pieranski, S.Przybyl and A. Stasiak: http://arxiv.org/abs/physics/0103080

Animation credit: based on a gif from Piotr Pieranski's web page: http://etacar.put.poznan.pl/piotr.pieranski/GordianUnknots.html

#mathematics #scienceeveryday
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