Apparently an 80s commerical for the helmet manufacturer Bell bore the slogan: "If you've got a $10 head, wear a $10 helmet". Nowadays it's a deeply-ingrained and widely accepted idea among bikers that it's worth spending a lot of money on your headgear. A top-of-the-line Arai can sell for almost four figures, particularly if you want a nice race rep design, but what are you getting for your money and, in particular, is it any safer than a helmet you pickup for a tenth of that price?

In the R programming language, the random number generator (RNG) is seeded each session using the current time and process ID. Via the magic of the popular Mersenne Twister PRNG, the values stored in .Random.seed are used sequentially each time "randomness" is invoked in a function. This means, of course, that the same function run in different R sessions can produce varying results, and in the case of modelling a system sensitive to initial conditions the observed differences could be huge.

As a LaTeX fan I'm used to using Beamer for presentations, but the built-in themes are definitely starting to show their age --- and writing a custom .sty file looks like a nightmare --- so for a while I've been looking at trying out an HTML5 framework.