II.—Ball or Pillow-form Structures in Sandstones

Clocking in Pillow Time without the Pillow

1512 normal enzyme. Then, they replaced the oxygen in question with a sulfur atom. The reaction didn’t work as well because, by the rules of chemistry, sulfur doesn’t like to bind to magnesium. But sulfur does like manganese and cadmium ions. So they replaced the magnesium with one of these other metal ions and measured the reaction. The researchers saw that these other metal ions restored (or ...

Cryptoendolithic alteration of Antarctic sandstones: Pioneers or opportunists?

[1] The cryptoendolithic habitat of the Antarctic Dry Valleys has been considered a good analogy for past Martian ecosystems, if life arose on the planet. Yet cryptoendoliths are thought to favor the colonization of rocks that have a preexisting porous structure, e.g., sandstones. This may weaken their significance as exact analogues of potential rockcolonizing organisms on Mars, given our curr...

Pillow Chess

In cylindrical chess, one plays on a regular chessboard with the pieces in their standard positions, but imagines that the left and right edges of the board are identified. So, for example, when a rook travels horizontally off the right-hand edge, it reappears in the same row on the left-hand side of the board. It is easy to make a cylindrical chessboard out of paper, by taping together the lef...

Sandstones and Conglomerates in Ohio

Stochastic reconstruction of sandstones

A simulated annealing algorithm is employed to generate a stochastic model for a Berea sandstone and a Fontainebleau sandstone, with each a prescribed two-point probability function, lineal-path function, and "pore size" distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparis...