12,303 research outputs found
Effects of Enamel Paint on the Behavior and Survival of the Periodical Cicada, \u3ci\u3eMagicicada Septendecim\u3c/i\u3e (Homoptera) and the Lesser Migratory Grasshopper, \u3ci\u3eMelanoplus Sanguinipes (Orthoptera).
We present information compiled from several studies on the effects of methods for marking individual arthropods on their longevity and behavior. Results from our own research on effects of enamel paint marking on two in- sect species, the periodical cicada, Magicicada septendecim, and the lesser migratory grasshopper, Melanoplus sanguinipes, are also presented. Neither species showed any adverse survivorship or behavioral effects from marking
An evaluation of helicopter noise and vibration ride qualities criteria
Two methods of quantifying helicopter ride quality; absorbed power for vibration only and the NASA ride comfort model for both noise and vibration are discussed. Noise and vibration measurements were obtained on five operational US Army helicopters. The data were converted to both absorbed power and DISC's (discomfort units used in the NASA model) for specific helicopter flight conditions. Both models indicate considerable variation in ride quality between the five helicopters and between flight conditions within each helicopter
Dipolar Bose gases: Many-body versus mean-field description
We characterize zero-temperature dipolar Bose gases under external spherical
confinement as a function of the dipole strength using the essentially exact
many-body diffusion Monte Carlo (DMC) technique. We show that the DMC energies
are reproduced accurately within a mean-field framework if the variation of the
s-wave scattering length with the dipole strength is accounted for properly.
Our calculations suggest stability diagrams and collapse mechanisms of dipolar
Bose gases that differ significantly from those previously proposed in the
literature
Design of a digital ride quality augmentation system for commuter aircraft
Commuter aircraft typically have low wing loadings, and fly at low altitudes, and so they are susceptible to undesirable accelerations caused by random atmospheric turbulence. Larger commercial aircraft typically have higher wing loadings and fly at altitudes where the turbulence level is lower, and so they provide smoother rides. This project was initiated based on the goal of making the ride of the commuter aircraft as smooth as the ride experienced on the major commercial airliners. The objectives of this project were to design a digital, longitudinal mode ride quality augmentation system (RQAS) for a commuter aircraft, and to investigate the effect of selected parameters on those designs
Multiple scattering of matter waves: an analytic model of the refractive index for atomic and molecular gases
We present an analytic model of the refractive index for matter waves
propagating through atomic or molecular gases. The model, which combines a WKB
treatment of the long range attraction with the Fraunhofer model treatment of
the short range repulsion, furnishes a refractive index in compelling agreement
with recent experiments of Jacquey et al. [Phys. Rev. Lett. 98, 240405 (2007)]
on Li atom matter waves passing through dilute noble gases. We show that the
diffractive contribution, which arises from scattering by a two dimensional
"hard core" of the potential, is essential for obtaining a correct imaginary
part of the refractive index.Comment: 5 pages, 1 figure, 2 table
Effects of Enamel Paint on the Behavior and Survival of the Periodical Cicada, \u3ci\u3eMagicicada Septendecim\u3c/i\u3e (Homoptera) and the Lesser Migratory Grasshopper, \u3ci\u3eMelanoplus Sanguinipes (Orthoptera).
We present information compiled from several studies on the effects of methods for marking individual arthropods on their longevity and behavior. Results from our own research on effects of enamel paint marking on two in- sect species, the periodical cicada, Magicicada septendecim, and the lesser migratory grasshopper, Melanoplus sanguinipes, are also presented. Neither species showed any adverse survivorship or behavioral effects from marking
Effects of a torsion field on Big Bang nucleosynthesis
In this paper it is investigated whether torsion, which arises naturally in
most theories of quantum gravity, has observable implications for the Big Bang
nucleosynthesis. Torsion can lead to spin flips amongst neutrinos thus turning
them into sterile neutrinos. In the early Universe they can alter the helium
abundance which is tightly constrained by observations. Here I calculate to
what extent torsion of the string theory type leads to a disagreement with the
Big Bang nucleosynthesis predictions.Comment: accepted by General Relativity and Gravitatio
Frequency Following Imaging of Electric Fields from Resonant Superconducting Devices using a Scanning Near-Field Microwave Microscope
We have developed a scanning near-field microwave microscope that operates at
cryogenic temperatures. Our system uses an open-ended coaxial probe with a 200
mm inner conductor diameter and operates from 77 to 300 K in the 0.01-20 GHz
frequency range. In this paper, we present microwave images of the electric
field distribution above a Tl2Ba2CaCu2O8 microstrip resonator at 77 K, measured
at several heights. In addition, we describe the use of a frequency-following
circuit to study the influence of the probe on the resonant frequency of the
device.Comment: 4 pages, postscript file with 6 figures conference proceeding for the
Applied Superconductivity Conference 199
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