The potential contribution of intercellular light reflectance to photosynthesis was investigated hy innitrating shade leaves with mineral oil. Inllltration of leaves of Hydrophyllum canadense and Asarum canadense with mineral oil decreased adaxial leaf reflectance but increased transmittance. As a result of the large increase in transmittance, infiltration caused a deerease in absorptance of 25% and 30% at 55t) and 750 nm, respectively. Thus, intercellular rellectance increa.sed absorptance in these species by this amount. In a comparison of sun and shade leaves oi Acer saccharum and Parthenocissus qtiinquefolia, oil infiltration decreased absorptance more in shade than in sun leaves. This difference suggests that the higher proportion of spongy mesophyll in shade leaves may increase internal light scattering and thus absorptance. The importance of the spongy mesophyll in increasing internal reflectance was also evident in comparisons of the optics of Populus leaves and in the fluorescence yield of oilinfiltrated leaves of several sun and shade species. Oil infiltration decrea.sed the quantum yield of fluoreseence (Fo) by 39-52% for shade leaves but only 21-25% for sun leaves. We conclude that the greater proportion of spongy parenchyma in shade leaves increased intercellular light scattering and thus absorptance. Direct measurenients with fibre-optic light probes of the distribution of light inside leaves of Hydrophyllum canadense confirmed that oil infiltration decreased the amount of back-scattered light and that most of the light scattering for this species occurred from the middle of the palisade layer to the middle of the spongy me.sophyll. We were not, however, able to assess the potential contribution of reflectance from the internal abaxial epidermis to total internal light scattering in these experiments. Using a mathematical model to compare the response of net photosynthesis (O2 flux) to incident irradiance for control leaves of H. canadense and theoretical leaves with no intercellular reflectance, we calculated that intercellular reflectance caused a 1-97-fold increase in photosynthesis at 20^molm"^s"' (incident photon flux density). This enhancement of ab.sorption and photosynthesis by inter-
SCoC is patient-centered, outcomes-driven, value-based approach for hospital-wide surgical patient safety. The principles of this value paradigm are adaptable to other hospitals as demonstrated in our longitudinal study in 3 hospital systems, and the initial experience of CoC suggests that this model will have benefit beyond surgical hospital cohort.
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