Improvements of a dynamic global vegetation model and simulations of carbon and water at an upland-oak forest

The interest in the development and improvement of dynamic global vegetation models （DGVMs）, which have the potential to simulate fluxes of carbon, water and nitrogen, along with changes in the vegetation dynamics, within an integrated system, has been increasing. In this paper, some numerical schemes and a higher resolution soil texture dataset were employed to improve the Sheffield Dynamic Global Vegetation Model （SDGVM）. Using eddy covariance-based measurements, we then tested the standard version of the SDGVM and the modified version of the SDGVM. Detailed observations of daily carbon and water fluxes made at the upland oak forest on the Walker Branch Watershed in Tennessee, USA offered a unique opportunity for these comparisons. The results revealed that the modified version of the SDGVM did a reasonable job of simulating the carbon and water flux and the variation of soil water content （SWC）. However, at the end of the growing season, it failed to simulate the effect of the limitations on the soil respiration dynamics and as a result underestimated this respiration. It was also noted that the modified version overestimated the increase in the SWC following summer rainfall, which was attributed to an inadequate representation of the ground water and thermal cycle.     

MACH'S Principle,Gravitation and Electromagnetism: The Electromagnetic Inertia of Charged Elementary Particles

The question of the magnitude and behaviour of the electromagnetic contribution to the mass of an elementary charged particle is explored. It is shown that, if the “cut-off” of relativistic quantum electrodynamics is taken as an approximation to the physical process embodied in the postulates: I. That the bare charge of an elementary particle may only emit and absorb virtual photons having energies that are integral multiples of some fundamental energy, and II. that the observed charge of an elementary particle is a constant independent of its “radius”, the electromagnetic mass of such a particle is always finite, even when the radius of the particle becomes zero. Alternative postulates that will resolve the cut-off dilemma are briefly discussed. It is noted that the “MACHianess” of electromagnetic mass (in terms of PAULI'S criterion for “MACHianess”) depends on the detailed structure of postulate II, and that extant experimental results do not permit one, at present, to decide the issue with certainty.