Upper atmosphere research: Reaction rate and optical measurements

The objective is to provide photochemical, kinetic, and spectroscopic information necessary for photochemical models of the Earth's upper atmosphere and to examine reactions or reactants not presently in the models to either confirm the correctness of their exclusion or provide evidence to justify future inclusion in the models. New initiatives are being taken in technique development (many of them laser based) and in the application of established techniques to address gaps in the photochemical/kinetic data base, as well as to provide increasingly reliable information

Using the LANDSAT data collection system for field geophysics: Operations in the British Virgin Islands

This particular application was to vertical geodesy by tide gauge and tiltmeter on a small desert island in the British Virgin Islands. The performance of the LANDSAT system under potentially marginal circumstances was found to be excellent

Spin-dependent resonant tunneling through semimetallic ErAs quantum wells

Resonant tunneling through semimetallic ErAs quantum wells embedded in GaAs structures with AlAs barriers was recently found to exhibit an intriguing behavior in magnetic fields which is explained in terms of tunneling selection rules and the spin-polarized band structure including spin-orbit coupling.Comment: 4 pages, figures supplied as self-unpacking figures.uu, uses epsfig.sty to incorporate figures in preprin

Two-Pulse Propagation in a Partially Phase-Coherent Medium

We analyze the effects of partial coherence of ground state preparation on two-pulse propagation in a three-level $\Lambda$ medium, in contrast to previous treastments that have considered the cases of media whose ground states are characterized by probabilities (level populations) or by probability amplitudes (coherent pure states). We present analytic solutions of the Maxwell-Bloch equations, and we extend our analysis with numerical solutions to the same equations. We interpret these solutions in the bright/dark dressed state basis, and show that they describe a population transfer between the bright and dark state. For mixed-state $\Lambda$ media with partial ground state phase coherence the dark state can never be fully populated. This has implications for phase-coherent effects such as pulse matching, coherent population trapping, and electromagnetically induced transparency (EIT). We show that for partially phase-coherent three-level media, self induced transparency (SIT) dominates EIT and our results suggest a corresponding three-level area theorem.Comment: 29 pages, 12 figures. Submitted to Phys. Rev.

On minimal coupling of the ABC-superparticle to supergravity background

By rigorous application of the Hamiltonian methods we show that the ABC-formulation of the Siegel superparticle admits consistent minimal coupling to external supergravity. The consistency check proves to involve all the supergravity constraints.Comment: 8 pages RevTex file, to appear in Phys. Rev.

Guide for Harvesting, Handling and Drying Peanuts.

4 p