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## Polygons!

Inspired by a Boing Boing post, I went on a bit of a shopping spree over at Shapeways and bought a bunch of models of objects that have been spinning around in my screen savers for many years. It's always nice to have an excuse to use my macro lens, and hey, who doesn't need more plastic junk on their desk?

And now, photos! Math lesson!

First up, the Sierpinski Gasket, a recursive fractal based subdividing a tetrahedron with itself. Basically you take a triangle and cut a triangle out of the middle so you are left with 3 triangles touching at the corners, and a hole. Repeat until forever. This model is by Wahtah and seems to be 5 iterations, which would be 4,096 of the smallest tetrahedrons.

This is called Sierpinski3D in XScreenSaver.

This is the similar Menger Sponge, which is the same idea but based on a cube instead of a tetrahedron: instead of cutting a triangle out of the center of a triangle, a cube is cut out of the center of itself. This is a much heavier (and thus more expensive) model because the figure itself encloses more space (since it hasn't been iterated to infinite depth). This model's by Bathsheba. It was really dusty with leftover placenta from the 3D printer's birthing vats. Four iterations, I think.

Fun fact! You can socket a Menger Sponge into a Sierpinski Gasket because a diagonal slice through three faces of a cube is an equilateral triangle.

Screen saver: Menger.

These next two are Hilbert Curves, a space-filling curve that can touch every point in a volume of space without ever intersecting itself. As a data structure, Hilbert paths are useful because ordering along the curve preserves locality: points that are close together along the curve are also close together in space.

The first model is of depth 3 and is by Henry Segman, and the second is of depth 4 and is by by Srjskam. The depth-4 one is very floppy, because it was printed with flexible plastic! Segman points out that the first one can be used with success as a ponytail scrunchie.

Screen saver: Hilbert.

Moving from fractals into higher dimensions, we reach that old standard, the Hypercube (AKA Tesseract, and why those are not the same page I do not know), or more accurately, some 3D objects that are shadows of the 4D object that is to the cube what the cube is to a square. I got two different ones of these, because there are many possible shadows. In the real 4D object, each of the six-faced enclosed areas are actual cubes rather than truncated pyramids or whatnot.

The screen saver that generates these is called Polytopes.

This is the Hyperdodecahedron, AKA the 120-Cell, the 4D analog of a dodecahedron (the 12-sided solid made of pentagons). In 4D, each of the enclosed cells is also a non-deformed dodecahedron. It's hard to think about. This one's also by Bathsheba, and is also produced by the Polytopes saver.

And finally... because my heart is not a stone, a Weighted Companion Cube by MaxSMoke, which is awesome because it was printed in color. Only minor assembly required. XScreenSaver: CompanionCube.

3D printing, man. So futurey.

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## I have fallen down a "Gold Guns Girls" hole.

I seem to have been listening to this song on repeat for an hour now. I recommend that you do as well.

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Current Music: duh

## DNA Lounge update

DNA Lounge update, wherein there are some photos.
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## I'll have the shrimp cocktail, with a teratoma on the side.

Eyeless shrimp and fish with lesions are becoming common, with BP oil pollution believed to be the likely cause.

Along with collapsing fisheries, signs of malignant impact on the regional ecosystem are ominous: horribly mutated shrimp, fish with oozing sores, underdeveloped blue crabs lacking claws, eyeless crabs and shrimp - and interviewees' fingers point towards BP's oil pollution disaster as being the cause.

According to Kuhns, at least 50 per cent of the shrimp caught in that period in Barataria Bay, a popular shrimping area that was heavily impacted by BP's oil and dispersants, were eyeless. Kuhns added: "Disturbingly, not only do the shrimp lack eyes, they even lack eye sockets."

"Some shrimpers are catching these out in the open Gulf [of Mexico]," she added, "They are also catching them in Alabama and Mississippi. We are also finding eyeless crabs, crabs with their shells soft instead of hard, full grown crabs that are one-fifth their normal size, clawless crabs, and crabs with shells that don't have their usual spikes... they look like they've been burned off by chemicals."

Darla Rooks, a lifelong fisherperson from Port Sulfur, Louisiana, told Al Jazeera she is finding crabs "with holes in their shells, shells with all the points burned off so all the spikes on their shells and claws are gone, misshapen shells, and crabs that are dying from within... they are still alive, but you open them up and they smell like they've been dead for a week".

Rooks is also finding eyeless shrimp, shrimp with abnormal growths, female shrimp with their babies still attached to them, and shrimp with oiled gills.

"We also seeing eyeless fish, and fish lacking even eye-sockets, and fish with lesions, fish without covers over their gills, and others with large pink masses hanging off their eyes and gills."