Navigating at night: fundamental limits on the sensitivity of radical pair magnetoreception under dim light.

Night-migratory songbirds appear to sense the direction of the Earth's magnetic field via radical pair intermediates formed photochemically in cryptochrome flavoproteins contained in photoreceptor cells in their retinas. It is an open question whether this light-dependent mechanism could be sufficiently sensitive given the low-light levels experienced by nocturnal migrants. The scarcity of available photons results in significant uncertainty in the signal generated by the magnetoreceptors distributed around the retina.

What effect has pneumococcal vaccination had on acute mastoiditis?

Background: Streptococcus pneumoniae is a frequent cause of acute mastoiditis. Despite the recent (2005) introduction of pneumococcal vaccination, mastoiditis incidence and severity may be increasing. This study aimed to assess the incidence, severity and microbiology of acute mastoiditis over an 11-year period.