Derek's interests

Derek's posts

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Here's a gorgeous photostream from a Japanese resercher working on computational origami. He's got a program called "Origamizer" that takes 3d surfaces and produces folding patterns like the metallic rabbit below.

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+George Hart has a nice puzzle/sculpture called the 12-card star. He taught participants at a workshop in San Antonio how to make one, and there's a picture of mine below.

You can build one too, using instructions on George's website:

http://georgehart.com/g4g10/

While you don't need math to see that this is cool, for those of you who like math, there's a bunch of fun stuff in this puzzle! One thing I noticed is that if you built one using 4 triples of identical cards, you could see in a concrete way that the symmetries of this shape are the same as the permutations of a 4-element set! You can read my blog post about it here:

https://dkwise.wordpress.com/2015/03/07/george-harts-12-card-star-and-suit-permutations/

You can build one too, using instructions on George's website:

http://georgehart.com/g4g10/

While you don't need math to see that this is cool, for those of you who like math, there's a bunch of fun stuff in this puzzle! One thing I noticed is that if you built one using 4 triples of identical cards, you could see in a concrete way that the symmetries of this shape are the same as the permutations of a 4-element set! You can read my blog post about it here:

https://dkwise.wordpress.com/2015/03/07/george-harts-12-card-star-and-suit-permutations/

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**A physicist looks at water resource problems.**

This sounds like it will be an interesting webcast lecture by Marcia C. Barbosa, live from the Perimeter Institute for Theoretical Physics this Wednesday.

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My tribute to Alexander Grothendieck in The New York Times

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Apparently,

(I hadn't realized these were available online until I saw a post on +Pablo Azero's page. Thanks, Pablo!)

**Richard Feynman**has a new blog! He's explaining vast amounts of basic physics to the masses, in his characteristic style.(I hadn't realized these were available online until I saw a post on +Pablo Azero's page. Thanks, Pablo!)

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This leaf is from the garden where I live. All the green has decayed away, leaving just a network of veins.

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Happy German-American Day!

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*SIGMA*(Symmetry, Integrability and Geometry: Methods and Applications) is a good math journal, where by "good" I mean "not evil". It's open access, free to authors, links to the arXiv version, puts the official published version on the arXiv, etc. ...

It's really very nice. But one has fund so much niceness somehow. Here's a letter I got from them...

--

Dear SIGMA authors,

We would like to thank you for co-operation with the journal

SIGMA (Symmetry, Integrability and Geometry: Methods and Applications)

http://www.emis.de/journals/SIGMA/

SIGMA is being published for nine years, and its current impact factor is 1.299.

SIGMA does not charge its readers for access, and despite this does

not charge authors for publication (i.e., it is no-fee open-access journal).

Moreover, SIGMA is not supported financially on a regular basis by any entity

(organization, foundation, fund, etc.) in Ukraine or abroad, including

the National Academy of Sciences of Ukraine, where the Editorial Office works.

Therefore, the journal has no revenue and steady sources of funding

whatsoever, and operates solely on the basis of the good will efforts

of its editors. All editorial work, including, but not limited to, the

copyediting, is done by volunteers free of charge.

SIGMA has no geographical concentration - its authors come

from 75 countries (USA 12.9%, Russia 8.1%, Japan 7.7%, France

6.7%, Italy 5.6%, Germany 4.3%, Spain 4.2%, UK 4,2%, Ukraine 4.0%,

Canada 3.8%, Mexico 3,7%, Australia 2.4%, Belgium 2.4%, Brazil

2,1%, other countries 28,0%), and so it actually belongs to all mathematical

physics community.

In principle, we can see three ways for funding of journal:

1) charging readers (subscription without open access);

2) charging authors to keep open access;

3) finding sponsors.

From the time of founding of the journal in 2005 until now we consistently avoided

resolving to first two options, and we would like to maintain this

position further on. But to do that we would need to find some

external funding.

As a first examples of such funding, we have received one-time

supports from the University Library of the Radboud University

Nijmegen (EUR 3000) and from Sociedad Mexicana de Fisica (USD 3500).

The relevant acknowledgments were published at the bottom of the main

page of the journal. But that covers only a small part of our costs.

If you would like to help in supporting, please contact in this respect

your university, professional societies or funds in your country.

Any amount would be a substantial support to our project.

We hope for your assistance and for any suggestions related to

this matter.

Sincerely yours,

Anatoly Nikitin, the Editor

http://www.emis.de/journals/SIGMA/

#openaccess

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As a guitarist, I'd have a hard time playing a guitar with no frets, at least when it comes to playing chords. But playing the theremin must be worse. Rather like playing a guitar with no

Here's the original theremin virtuoso Clara Rockmore rocking out on the theremin.

If you want to know how a theremin works, look here:

http://en.wikipedia.org/wiki/Theremin

*neck*. Precise hand placement is crucial, but there's no tactile point of reference. I'd like to try it sometime.Here's the original theremin virtuoso Clara Rockmore rocking out on the theremin.

If you want to know how a theremin works, look here:

http://en.wikipedia.org/wiki/Theremin

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When I think of ancient wisdom stored up in trees, I think of tales like the ones told by Lewis and Tolkien. But here, Japanese astronomers have consulted ancient trees who have told them of some high energy event (perhaps a supernova) that happened more than 1200 years ago.

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