Physics of the Pseudogap State: Spin-Charge Locking

The properties of the pseudogap phase above Tc of the high-Tc cuprate superconductors are described by showing that the Anderson-Nambu SU(2) spinors of an RVB spin gap 'lock' to those of the electron charge system because of the resulting improvement of kinetic energy. This enormously extends the range of the vortex liquid state in these materials. As a result it is not clear that the spinons are ever truly deconfined. A heuristic description of the electrodynamics of this pseudogap-vortex liquid state is proposed.Comment: Submitted to Phys Rev Letter

Static highly elliptical orbits using hybrid low-thrust propulsion

Static highly-elliptical orbits enabled using hybrid solar-sail/solar-electric propulsion are investigated. These newly proposed orbits, termed Taranis orbits, have free selection of ‘critical inclination’ and use low-thrust propulsion to compensate for the drift in argument of perigee caused by Earth’s gravitational field. In this paper, a 12-hr Taranis orbit with an inclination of 90deg is developed to illustrate the principle. The acceleration required to enable this novel orbit is made up partly by the acceleration produced by solar-sails of various characteristic accelerations, and the remainder supplied by the electric thruster. Order of magnitude mission lifetimes are determined, a strawman mass budget is also developed for two system constraints, firstly spacecraft launch-mass is fixed, and secondly the maximum thrust of the thruster is constrained. Fixing maximum thrust increases mission lifetimes, and solar-sails are considered near to mid-term technologies. However, fixing mass results in negligible increases in mission lifetimes for all hybrid cases considered, solar sails also require significant development. This distinction highlights an important contribution to the field, illustrating that addition of a solar-sail to an electric propulsion craft can have negligible benefit when mass is the primary system constraint. Technology requirements are also outlined, including sizing of solar-arrays, propellant tanks and solar sails

Review: Ocean Recovery: A Sustainable Future for Global Fisheries?

Revie

Notes on the Brown Widow Spider, Latrodectus Geometricus (Araneae: Theridiidae) in Brazil

Three species of the cosmopolitan genus Latrodectus were reported by Bucherl (1964) as occurring in Brazil: L. mactans mactans (Fabricius) from Recife, Pernambuco and from P6rto Alegre, Rio Grande do Sul; L. curacaviensis (Muller) from the beaches of Guanabara and Bahia; and L. geometricus C. L. Koch from the city of P6rto Alegre, Rio Grande do Sul and from the states of Minas Gerais, Bahia and Rio de Janeiro. Levi (1959) cited records of L. geometricus from the states of Paraiba, Pernarnbuco, Minas Gerais and Rio de Janeiro. In the United States L. geometricus has been reported as an introduced species from both Hawaii (Levi, 1967) and Florida (Levi and Levi, 1968). The present paper contains observations on L. geometricus in the state of Espirito Santo and in the city of Manaus, Amazonas, Brazil in 1969 and 1970

Bose Fluids Above Tc: Incompressible Vortex Fluids and "Supersolidity"

This paper emphasizes that non-linear rotational or diamagnetic susceptibility is characteristic of Bose fluids above their superfluid Tcs, and for sufficiently slow rotation or weak B-fields amounts to an incompressible response to vorticity. The cause is a missing term in the conventionally accepted model Hamiltonian for quantized vortices in the Bose fluid. The resulting susceptibility can account for recent observations of Chan et al on solid He, and Ong et al on cuprate superconductors

Dynamic testing of complex structures

Response of structure is determined under impulses large enough to create severe strains. Electrodynamic shaker can provide impulses to nearly any point on structure and can deliver repeated pulses of varying force and duration