Our memory for words can be modelled as a network in which each point represents a different word, with each linked to words that relate to it. Psychologist Tom Griffiths and colleagues at the University of California, Berkeley, wondered whether the ease with which the brain retrieves words is similar to the way that websites are ranked by PageRank: by the number of sites that link to them.

It seems it might. In tests against other word-retrieval algorithms, PageRank most clearly matched the human model (Psychological Science, vol 18, p 1069). The results suggest human memory studies could be improved by examining the tricks that search engines employ, and vice versa, says Griffiths.

Using a laser, some gas, and a row of magnets, an international team of physicists has put together a source of “synchrotron light”, which they say can be easily upgraded to produce intense, ultra-short pulses of X-rays – ideal for probing the intricate structure of many kinds of matter.

“If it works out, you could have one of these in every university,” says the team’s leader Dino Jaroszynski of Strathclyde University in Scotland.

The prototype is an attempt to miniaturise the synchrotron light source. Synchrotrons are in great demand because their intense X-ray beams have so many uses, from analysing biological molecules to etching electronic components and seeing inside microscopic fossils.

But today’s synchrotrons are large-scale facilities such as the Diamond Light Source in Oxfordshire, UK. There, a 100-metre-wide particle accelerator boosts electrons up to high speed, and the electrons generate X-rays when they fly through an undulating magnetic field.

Mammals, including us, have two copies of each gene: one from the mother and one from the father. Normally, both are expressed, but occasionally one is imprinted, or silenced, which gives the other the deciding role. If this active gene is a mutation that would otherwise have been recessive, it can lead to disease. Conversely, if the silenced gene is harmful in some way, imprinting can be beneficial.

Investigating this phenomenon is difficult, however, as often the only distinguishing feature of an imprinted gene is that it has a methyl group attached, and this doesn’t show up in ordinary gene scans. Although 1 per cent of the 20,000 genes found on chromosomes 1 to 23 are estimated to be imprinted, only 40 have actually been found. “If you went through …