Gov-Arrrgh-Nance: Jolly Rogers and Dodgy Rulers

Jolly SAD.

Examples of phasing macromolecular crystal structures based on single-wavelength anomalous dispersion (SAD) show that this approach is more powerful and may have more general application in structural biology than was anticipated. Better data-collection facilities and cryogenic techniques, coupled with powerful programs for data processing, phasing, density modification and automatic model buil...

The Nance-Horan syndrome.

Is it jolly SAD?

Examples of phasing macromolecular crystal structures based on single-wavelength anomalous dispersion (SAD) have demonstrated that this approach may have general applications in structural biology. With better data-collection facilities and cryogenic techniques, combined with powerful data-processing, phasing and density-modification programs, the SAD approach may prove simpler than phasing fro...

Cosmic rulers

We derive general covariant expressions for the six independent observable modes of distortion of ideal standard rulers in a perturbed Friedmann-Robertson-Walker spacetime. Our expressions are gauge invariant and valid on the full sky. These six modes are most naturally classified in terms of their rotational properties on the sphere, yielding two scalars, two vector (spin-1), and two tensor (s...

Molecular rulers?

What is a ‘molecular ruler’? The lengths of many linear polymers in biology are specified with remarkably accuracy, indicating they have very similar or the same numbers of subunits. Examples include bacteriophage tails, bacterial flagellum hooks, bacterial ‘injectisome’ needles, and the thin and thick filaments of striated muscles. Such exact assembly requires explanation, because the same sub...