ECONOMIES OF SCALE IN THE GREENHOUSE FLORICULTURE INDUSTRY

Crop Production/Industries,

Structure of the nucleon and spin-polarizabilities

Spin-polarizabilities are predicted by calculating the cross-section difference $\sigma_{3/2}-\sigma_{1/2}$ from available data for the resonance couplings $A_{3/2}$ and $A_{1/2}$ and CGLN amplitudes. The forward spin-polarizabilities are predicted to be $\gamma^{(p)}_0=-0.58\pm 0.20$ and $\gamma^{(n)}_0=+0.38\pm 0.22$ in units of $10^{-4}$fm$^4$ where the different signs are found to be due to the isospin dependencies of the $E_{0+}$ and the $(M,E)^{(1/2)}_{1+}$ amplitudes. The backward spin-polarizabilities are predicted to be $\gamma^{(p)}_\pi=-36.6$ and $\gamma^{(n)}_\pi=+58.3$, to be compared with the experimental values $\gamma^{(p)}=-36.4\pm 1.5$ and $\gamma^{(n)}_\pi=+58.6\pm 4.0$. Electric $\gamma_E$ and magnetic $\gamma_M$ spin-polarizabilities are introduced and discussed in terms of the $E1$ and $M1/E2$ components of the photo-absorption cross section of the nucleon.Comment: 20 pages, 5 figures, 6 table

Statistics of the Energy Dissipation Rate and Local Enstrophy in Turbulent Channel Flow

Using high-resolution direct numerical simulations, the height and Reynolds number dependence of higher-order statistics of the energy dissipation rate and local enstrophy are examined in incompressible, fully-developed turbulent channel flow. The statistics are studied over a range of wall distances, spanning the viscous sublayer to the channel flow centerline, for friction Reynolds numbers $Re_\tau = 180$ and $Re_\tau = 381$. The high resolution of the simulations allows dissipation and enstrophy moments up to fourth order to be calculated. These moments show a dependence on wall distance, and Reynolds number effects are observed at the edge of the logarithmic layer. Conditional analyses based on locations of intense rotation are also carried out in order to determine the contribution of vortical structures to the dissipation and enstrophy moments. Our analysis shows that, for the simulation at the larger Reynolds number, small-scale fluctuations of both dissipation and enstrophy become relatively constant for $z^+ \gtrsim 100$.Comment: Accepted by Physica

Sometimes a Colonnade is Just a Porch

The history of modern architecture in the twentieth century, and into the twenty-first, is periodically concerned with the questions: who is Modern, what is Modern, what is Modern enough, and what does Modern mean in social and political terms? In a practical sense, the ideological battles between the “Moderns” and the “Ancients” over the past century have resembled the politics of a banana republic