Light beams can be engineered to carry orbital angular momentum, with application as, for instance, optical 'spanners' — essentially a 'twisted' variant of the more familiar optical tweezers. Here it is shown that it is, in principle, possible to engineer similar behaviour into an electron beam. Such a beam could find use in a variety of spectroscopy and microscopy techniques

It has been inferred that, during the Archaean eon, there must have been a high concentration of atmospheric CO2 and/or CH4, causing a greenhouse effect that would have compensated for the lower solar luminosity at the time and allowed liquid water to be stable in the hydrosphere. Here it is shown, however, that the mineralogy of Archaean sediments is inconsistent with such high concentrations of greenhouse gases. Instead it is proposed that a lower albedo on the Earth helped to moderate surface temperature

It has been thought that the basal metabolic rate of organisms increases as body mass is raised to some power, p. But the value of p has proved controversial, with both 2/3 and 3/4 being proposed. It is found here that the relationship between mass and metabolic rate does not follow a pure power law at all, and requires a quadratic term to account for curvature. Taking temperature and phylogeny into account, this explains why different data sets have produced different exponents when a power law has been fitted