Circadian rhythms have significant effects on leaf-to-canopy scale gas exchange under field conditions.

Background: Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO and HO vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy gas exchange at the Montpellier European Ecotron.

Visual hallucinations: charles bonnet syndrome.

The following is a case of Charles Bonnet syndrome in an 86-year-old woman who presented with visual hallucinations. The differential diagnosis of visual hallucinations is broad and emergency physicians should be knowledgeable of the possible etiologies.