1,391 research outputs found
Wireless telemetry system for floating bodies
Unit includes rugged waterproof cables and equipment containers, low power, sturdy antenna construction, and easy equipment setup and serviceability. Accuracy and reliability of entire measurement system were not sacrificed
New record, host and localities of bat mite of genusChirnyssoides (Acari, Sarcoptiformes, Sarcoptidae)
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Integrating Cognitive Capabilities in a Real Time Task
NTD-Soar is a model of the perceptual, cognitive, and motor actions performed by the NASA Test Director as he utilizes the materials in his surroundings and communicates with others to prepare for a Space Shuttle Launch. The model, built within the framework of a serial symbolic architecture, is based on a number of independently designed general cognitive capabilities as well as a cognitive analysis of a particular task. This paper presents a detailed description of the model and an assessment of its performance when compared to human data. NTD-Soar's ability to display human-like real-time performance demonstrates that symbolic models with a serial bottleneck can account for complex behaviors which appear to happen in parallel, simply by opportunistically interleaving small elements of the different subtasks
Gap soliton dynamics in an optical lattice as a parametrically driven pendulum
A long wavelength optical lattice is generated in a two-level medium by
low-frequency contrapropagating beams. Then a short wave length gap soliton
generated by evanescent boundary instability (supratransmission) undergoes a
dynamics shown to obey the Newton equation of the parametrically driven
pendulum, hence presenting extremely rich, possibly chaotic, dynamical
behavior. The theory is sustained by numerical simulations and provides an
efficient tool to study soliton trajectories
Development of superconducting YBa2Cu3O(x) wires with low resistance electrical contacts
Materials exhibiting superconductivity above liquid nitrogen temperatures (77 K) will enable new applications of this phenomena. One of the first commercial applications of this technology will be superconducting magnets for medical imaging. However, a large number of aerospace applications of the high temperature superconducting materials have also been identified. These include magnetic suspension and balance of models in wind tunnels and resistanceless leads to anemometers. The development of superconducting wires fabricated from the ceramic materials is critical for these applications. The progress in application of a patented fiber process developed by Clemson University for the fabrication of superconducting wires is reviewed. The effect of particle size and heat treatment on the quality of materials is discussed. Recent advances made at Christopher Newport College in the development of micro-ohm resistance electrical contacts which are capable of carrying the highest reported direct current to this material is presented
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Mites Parasitic on Australasian and African Spiders Found in the Pet Trade; a Redescription of Ljunghia pulleinei Womersley
Parasitic mites associated with spiders are spreading world-wide through the trade in tarantulas and other pet species.
Ljunghia pulleinei Womersley, a mesostigmatic laelapid mite originally found in association with the mygalomorph spider
Selenocosmia stirlingi Hogg (Theraphosidae) in Australia, is redescribed and illustrated on the basis of specimens from the
African theraphosid spider Pterinochilus chordatus (Gersta¨cker) kept in captivity in the British Isles (Wales). The mite is known
from older original descriptions of Womersley in 1956; the subsequent redescription of Domrow in 1975 seems to be
questionable in conspecificity of treated specimens with the type material. Some inconsistencies in both descriptions are
recognised here as intraspecific variability of the studied specimens. The genus Arachnyssus Ma, with species A. guangxiensis
(type) and A. huwenae, is not considered to be a valid genus, and is included in synonymy with Ljunghia Oudemans. A new
key to world species of the genus Ljunghia is provided
Local-field correction to one- and two-atom van der Waals interactions
Based on macroscopic quantum electrodynamics in linearly and causally
responding media, we study the local-field corrected van der Waals potentials
and forces for unpolarized ground-state atoms placed within a magnetoelectric
medium of arbitrary size and shape. We start from general expressions for the
van der Waals potentials in terms of the (classical) Green tensor of the
electromagnetic field and the atomic polarizability and incorporate the
local-field correction by means of the real-cavity model. In this context,
special emphasis is given to the decomposition of the Green tensor into a
medium part multiplied by a global local-field correction factor and, in the
single-atom case, a part that only depends on the cavity characteristics. The
result is used to derive general formulas for the local-field corrected van der
Waals potentials and forces. As an application, we calculate the van der Waals
potential between two ground-state atoms placed within magnetoelectric bulk
material.Comment: 9 pages, 2 figures, corrections according to erratu
Knotlike Cosmic Strings in The Early Universe
In this paper, the knotlike cosmic strings in the Riemann-Cartan space-time
of the early universe are discussed. It has been revealed that the cosmic
strings can just originate from the zero points of the complex scalar
quintessence field. In these strings we mainly study the knotlike
configurations. Based on the integral of Chern-Simons 3-form a topological
invariant for knotlike cosmic strings is constructed, and it is shown that this
invariant is just the total sum of all the self-linking and linking numbers of
the knots family. Furthermore, it is also pointed out that this invariant is
preserved in the branch processes during the evolution of cosmic strings
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