Notes on SU(3) Structures in Type IIB Supergravity

We study solutions of type IIB supergravity with an SU(3) structure group and four dimensional Poincare invariance and present relations among the bosonic fields which follow from the supersymmetry variations. We make explicit some results which also follow from the more general case of an SU(2) structure and give some short comments applicable to general supersymmetric solutions. We also provide simplified relations appropriate for duals of gauge theory renormalization group flows, and use these to derive the supergravity solution for a bound state of (p,q)5-branes and D3-branes.Comment: 14p, JHEP3.cls, v2 typos corrected, refs adde

Satellite-aided mobile communications limited operational test in the trucking industry

An experiment with NASA's ATS-6 satellite, that demonstrates the practicality of satellite-aided land mobile communications is described. Satellite communications equipment for the experiment was designed so that it would be no more expensive, when mass produced, than conventional two-way mobile radio equipment. It embodied the operational features and convenience of present day mobile radios. Vehicle antennas 75 cm tall and 2 cm in diameter provided good commercial quality signals to and from trucks and jeeps. Operational applicability and usage data were gathered by installing the radio equipment in five long-haul tractor-trailer trucks and two Air Force search and rescue jeeps. Channel occupancy rates are reported. Air Force personnel found the satellite radio system extremely valuable in their search and rescue mission during maneuvers and actual rescue operations. Propagation data is subjectively analyzed and over 4 hours of random data is categorized and graded as to signal quality on a second by second basis. Trends in different topographic regions are reported. An overall communications reliability of 93% was observed despite low satellite elevation angles ranging from 9 to 24 degrees

Tension dynamics and viscoelasticity of extensible wormlike chains

The dynamic response of prestressed semiflexible biopolymers is characterized by the propagation and relaxation of tension, which arises due to the near inextensibility of a stiff backbone. It is coupled to the dynamics of contour length stored in thermal undulations, but also to the local relaxation of elongational strain. We present a systematic theory of tension dynamics for stiff yet extensible wormlike chains. Our results show that even moderate prestress gives rise to distinct Rouse-like extensibility signatures in the high-frequency viscoelastic response.Comment: 4 pages, 1 figure; corrected typo