It has been argued that cellphones are safe because a single microwave photon does not have enough energy to break a chemical bond. We show that cellphone technology operates in the classical wave limit, not the single photon limit. Based on energy densities relative to thermal energy, we estimate thresholds at which effects could be possible. These seem to correspond somewhat with many experim...

Why do plants reflect in the green and have a "red edge" in the red, and should extrasolar photosynthesis be the same? We provide (1) a brief review of how photosynthesis works, (2) an overview of the diversity of photosynthetic organisms, their light harvesting systems, and environmental ranges, (3) a synthesis of photosynthetic surface spectral signatures, and (4) evolutionary rationales for ...

The vertical migration behaviour of diatom assemblages inhabiting Wadden Sea sediments near Dangast (Germany) was investigated using cryo-scanning electron microscopy. The diatom assemblages were dominated by small Navicula species. Intertidal sediments which were located at different distances from the high tide level or stayed submerged even throughout low tides were chosen. Samples were prep...

The effects of radiation drag force on the structure of relativistic electronpositron and electron-proton outflows are considered within the one-fluid approximation. It is shown that for a magnetically-dominated outflow the drag force does not change the particle energy inside the fast magnetosonic surface. In this region the action of the drag results in a diminishing of the Poynting flux, not...

Using a microscopic theory, we determine the entangled n-photon state generated both by the nonlinear process of spontaneous n-photon parametric down-conversion and in a cascade of n21 crystals with twophoton parametric down-conversions. Expressions for the entangled n-photon absorption cross sections are also obtained. The absorption cross sections exhibit a linear dependence on the photon flu...

We developed a simulation model of an integrated CMOS-based imaging platform for use with bioluminescent DNA microarrays. We formulate the complete kinetic model of ATP based assays and luciferase label-based assays. The model first calculates the number of photons generated per unit time, i.e., photon flux, based upon the kinetics of the light generation process of luminescence probes. The pho...

Is radiation damage to cryopreserved protein crystals strictly proportional to accumulated dose at the high-flux density of beams from undulators at third-generation synchrotron sources? The answer is "yes," for overall damage to several different kinds of protein crystals at flux densities up to 10(15) ph/sec/mm(2) (APS beamline 19-ID). We find that, at 12 keV (1 A wavelength), about ten absor...

Apparent photosynthesis and dark respiration were followed during development in four light environments of leaves of Fragaria virginiana Duchesne. Leaf expansion was completed more rapidly the higher the growth photon flux density and leaves senesced more quickly in high light. Maximum photosynthetic capacity coincided with the completion of blade expansion and declined quickly thereafter. Lea...