Noise generation in the solid Earth, oceans, and atmosphere, from non-linear interacting surface gravity waves in finite depth

Oceanic pressure measurements, even in very deep water, and atmospheric pressure or seismic records, from anywhere on Earth, contain noise with dominant periods between 3 and 10 seconds, that is believed to be excited by ocean surface gravity waves. Most of this noise is explained by a nonlinear wave-wave interaction mechanism, and takes the form of surface gravity waves, acoustic or seismic waves. Previous theoretical works on seismic noise focused on surface (Rayleigh) waves, and did not consider finite depth effects on the generating wave kinematics. These finite depth effects are introduced here, which requires the consideration of the direct wave-induced pressure at the ocean bottom, a contribution previously overlooked in the context of seismic noise. That contribution can lead to a considerable reduction of the seismic noise source, which is particularly relevant for noise periods larger than 10 s. The theory is applied to acoustic waves in the atmosphere, extending previous theories that were limited to vertical propagation only. Finally, the noise generation theory is also extended beyond the domain of Rayleigh waves, giving the first quantitative expression for sources of seismic body waves. In the limit of slow phase speeds in the ocean wave forcing, the known and well-verified gravity wave result is obtained, which was previously derived for an incompressible ocean. The noise source of acoustic, acoustic-gravity and seismic modes are given by a mode-specific amplification of the same wave-induced pressure field near the zero wavenumber.Comment: Paper accepted for publication in the Journal of Fluid Mechanic

New revision underway: American beetles : a handbook of the beetles of Nearctic America

Several Coleopterists have been asked to revise the family sections, working from diskettes modified and provided from the original "Beetles of the United States." They will rewrite these sections, and will be recognized as the author of the section. They are asked to sign a writing contract with the publisher. Other Coleopterists have been asked to review the family sections of the new book. These persons are acknowledged in the family section text

Preponderance of Late-spiking Neurons in Rat Lateral Amygdala

Whole-cell recordings from rat lateral amygdala (LA) revealed two populations of principal neurons, that have similar pyramid-like morphologies but differing in firing pattern: late-spiking (LS, 66%) and regular-spiking (RS, 34%). The presence of large numbers of LS neurons arguably supports recent suggestions that the LA should be considered to be a functional extension of perirhinal cortex

Gamma-ray emission from globular clusters

Over the last few years, the data obtained using the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope has provided new insights on high-energy processes in globular clusters, particularly those involving compact objects such as Millisecond Pulsars (MSPs). Gamma-ray emission in the 100 MeV to 10 GeV range has been detected from more than a dozen globular clusters in our galaxy, including 47 Tucanae and Terzan 5. Based on a sample of known gamma-ray globular clusters, the empirical relations between gamma-ray luminosity and properties of globular clusters such as their stellar encounter rate, metallicity, and possible optical and infrared photon energy densities, have been derived. The measured gamma-ray spectra are generally described by a power law with a cut-off at a few gigaelectronvolts. Together with the detection of pulsed gamma-rays from two MSPs in two different globular clusters, such spectral signature lends support to the hypothesis that gamma-rays from globular clusters represent collective curvature emission from magnetospheres of MSPs in the clusters. Alternative models, involving Inverse-Compton (IC) emission of relativistic electrons that are accelerated close to MSPs or pulsar wind nebula shocks, have also been suggested. Observations at >100 GeV by using Fermi/LAT and atmospheric Cherenkov telescopes such as H.E.S.S.-II, MAGIC-II, VERITAS, and CTA will help to settle some questions unanswered by current data.Comment: 11 pages, 7 figures, 2 tables, J. Astron. Space Sci., in pres

Navier-Stokes calculations for the vortex of a rotor in hover

An efficient finite-difference scheme for the solution of the incompressible Navier-Stokes equation is used to study the vortex wake of a rotor in hover. The solution Procedure uses a vorticity-stream function formulation and incorporates an asymptotic far-field boundary condition enabling the size of the computational domain to be reduced in comparison to other methods. The results from the present method are compared with experimental data obtained by smoke flow visualization and hot-wire measurements for several rotor blade configurations

THE IMPACTS ON THE U.S. GRAPEFRUIT INDUSTRY FROM BANNING THE PESTICIDE SODIUM ORTHO-PHENYLPHENATE

Sodium Ãœrtho-phenylphenate (SOPP) is a postharvest pesticide commonly used on citrus. SOPP poses some food safety risks and is currently in the Environmental Protection Agency's Stage IV of the pesticide re-registration process. Costs to the fresh grapefruit industry are estimated for increases in the postharvest loss rates of fresh grapefruit following an SOPP ban. The ban's effects on domestic and export sales of fresh and processed grapefruit are estimated.Agricultural and Food Policy,