Aug. 5th, 2008
I love science.
Aug. 5th, 2008 04:38 pmJules Mikhael and his colleagues didn’t set out to make a material with a structure that had never been seen before, much less one that combines order and irregularity in a whole new way, one that Archimedes hinted at 2,000 years ago, one bound together by the Fibonacci sequence. They just wanted to understand a quasicrystal.
Even that wasn’t such a modest goal, because quasicrystals are pretty odd critters. Slice one in half, and there is a sort of mosaic with repeating shapes like tiles, much like a crystal. But here’s the bizarre part: Spin the resulting mosaic a fifth of a turn and often its tiles will line up exactly as they were before you spun it.
But that kind of five-fold symmetry is “forbidden,” because mathematicians have shown that no repeating flat pattern has it. That’s why you’ve never seen a bathroom tiled with pentagons—it’d be impossible to cover the whole surface with no gaps.
The secret of a quasicrystal is that its patterns never repeat. The tile shapes within the quasicrystal combine and recombine, with one area perhaps looking similar to another but then skipping off in its own unique formation. This eternal irregularity also gives quasicrystals remarkable, intriguing properties. For example, they tend to be slippery like Teflon, and even when made from metals, they’re good insulators.
Physicists have never really understood why quasicrystals have these properties, though.
Even that wasn’t such a modest goal, because quasicrystals are pretty odd critters. Slice one in half, and there is a sort of mosaic with repeating shapes like tiles, much like a crystal. But here’s the bizarre part: Spin the resulting mosaic a fifth of a turn and often its tiles will line up exactly as they were before you spun it.
But that kind of five-fold symmetry is “forbidden,” because mathematicians have shown that no repeating flat pattern has it. That’s why you’ve never seen a bathroom tiled with pentagons—it’d be impossible to cover the whole surface with no gaps.
The secret of a quasicrystal is that its patterns never repeat. The tile shapes within the quasicrystal combine and recombine, with one area perhaps looking similar to another but then skipping off in its own unique formation. This eternal irregularity also gives quasicrystals remarkable, intriguing properties. For example, they tend to be slippery like Teflon, and even when made from metals, they’re good insulators.
Physicists have never really understood why quasicrystals have these properties, though.
The p53rd Psalm
Aug. 5th, 2008 07:30 pmp53 is my shepherd, I shall not cycleFrom PZ Myers
It maketh me to lie down in G1
It leadeth me beside still nucleotide pools
It restoreth my genome
It leadeth me past the restriction point for replication's sake
Even though I walk through the valley of the shadow of the cobalt irradiator
I shall fear no gamma rays, for thou art Guardian of the Genome
Thy amino and thy carboxy termini, they comfort me
Thou maintainest my genomic stability in the presence of mine enemies
Thou annointest my nucleus with p21/WAF1/Cip1/Sdi1/Pic1
my cyclin dependent kinases overflow
Surely pRb phosphorylation and E2F activation shall follow me
all the cycles of my life
and I shall dwell in a non-tumorigenic state until senescence