Analog Processing Assembly for the Wake Vortex Lidar Experiment

The Federal Aviation Administration (FAA) and NASA have initiated a joint study in the development of reliable means of tracking, detecting, measuring, and predicting trailing wake-vortices of commercial aircraft. Being sought is an accurate model of the wake-vortex hazard, sufficient to increase airport capacity by reducing minimum safe spacings between planes. Several means of measurement are being evaluated for application to wake-vortex detection and tracking, including Doppler RADAR (Radio Detection and Ranging) systems, 2-micron Doppler LIDAR (Light Detection And Ranging) systems, and SODAR (Sound Detection And Ranging) systems. Of specific interest there is the lidar system, which has demonstrated numerous valuable capabilities as a vortex sensor Aerosols entrained in the vortex flow make the wake velocity signature visible to the lidar, (the observable lidar signal is essentially a measurement of the line-of-sight velocity of the aerosols). Measurement of the occurrence of a wake vortex requires effective reception and monitoring of the beat signal which results from the frequency-offset between the transmitted pulse and the backscattered radiation. This paper discusses the mounting, analysis, troubleshooting, and possible use of an analog processing assembly designed for such an application

Metabolic Activity of the Epiphytic Community Associated with Spartina alterniflora

Primary production and respiration rates were determined for two epiphytic communities associated with Spartina alternifloraLoisel., in the southwestern Barataria Bay area of Louisiana. The communities studied were: (1) a shoreline community and (2) a community 1.5 meters inland from the shoreline site. Annual mean net production and respiration rates for the shoreline community were 25.8 and -19.6 mg C • (m2 substrate area)-1 • h-1 respectively;whereas the inland community showed corresponding rates of -3.3 and -12.5 mg C • (m2 substrate area)-1 • h-1, respectively. Thus, the shoreline community was a net contributor to system production; the inland community was an energy sink. The inland community was elevated 15 to 20 cm above the shoreline community, lacked the conspicuous filamentous algal growth common at the shoreline location, and had a significantly smaller diatom population. The role of epiphytes is speculated to be one of quality rather than quantity production

Metabolic Activity of the Epiphytic Community Associated with Spartina alterniflora

Primary production and respiration rates were determined for two epiphytic communities associated with Spartina alternifloraLoisel., in the southwestern Barataria Bay area of Louisiana. The communities studied were: (1) a shoreline community and (2) a community 1.5 meters inland from the shoreline site. Annual mean net production and respiration rates for the shoreline community were 25.8 and -19.6 mg C • (m2 substrate area)-1 • h-1 respectively;whereas the inland community showed corresponding rates of -3.3 and -12.5 mg C • (m2 substrate area)-1 • h-1, respectively. Thus, the shoreline community was a net contributor to system production; the inland community was an energy sink. The inland community was elevated 15 to 20 cm above the shoreline community, lacked the conspicuous filamentous algal growth common at the shoreline location, and had a significantly smaller diatom population. The role of epiphytes is speculated to be one of quality rather than quantity production

Coherence as ultrashort pulse train generator

Intense, well-controlled regular light pulse trains start to play a crucial role in many fields of physics. We theoretically demonstrate a very simple and robust technique for generating such periodic ultrashort pulses from a continuous probe wave which propagates in a dispersive thermal gas media

Laser-Induced Plasma Analysis for Surrogate Nuclear Debris

This work identifies analytical lines in laser-induced plasma for chemical analyses of major elements found in surrogate nuclear debris. These lines are evaluated for interferences and signal strength to insure they would be useful to measure relative concentrations. Compact, portable instruments are employed and can be included as part of a mobile nuclear forensics laboratory for field screening of nuclear debris and contamination. The average plasma temperature is measured using the well-established Boltzmann plot technique, and plasma\u27s average electron density is determined using empirical formulae based on Stark broadening of the H-alpha line. These measurements suggest existence of partial local thermal equilibrium

Transient Dynamics in Magnetic Force Microscopy for a Single-Spin Measurement

We analyze a single-spin measurement using a transient process in magnetic force microscopy (MFM) which could increase the maximum operating temperature by a factor of Q (the quality factor of the cantilever) in comparison with the static Stern-Gerlach effect. We obtain an exact solution of the master equation, which confirms this result. We also discuss the conditions required to create a macroscopic Schrodinger cat state in the cantilever.Comment: 22 pages 2 figure

The Magnetic Casimir Effect

The Casimir effect results from alterations of the zero-point electromagnetic energy introduced by boundary-conditions. For ferromagnetic layers separated by vacuum (or a dielectric) such boundary-conditions are influenced by the magneto-optical Kerr effect. We will show that this gives rise to a long-range magnetic interaction and discuss the effect for two different configurations (magnetization parallel and perpendicular to the layers). Analytical expressions are derived for two models and compared to numerical calculations. Numerical calculations of the effect for Fe are also presented and the possibility of an experimental observation of the Casimir magnetic interaction is discussed

Quantum Measurement of a Single Spin using Magnetic Resonance Force Microscopy

Single-spin detection is one of the important challenges facing the development of several new technologies, e.g. single-spin transistors and solid-state quantum computation. Magnetic resonance force microscopy with a cyclic adiabatic inversion, which utilizes a cantilever oscillations driven by a single spin, is a promising technique to solve this problem. We have studied the quantum dynamics of a single spin interacting with a quasiclassical cantilever. It was found that in a similar fashion to the Stern-Gerlach interferometer the quantum dynamics generates a quantum superposition of two quasiclassical trajectories of the cantilever which are related to the two spin projections on the direction of the effective magnetic field in the rotating reference frame. Our results show that quantum jumps will not prevent a single-spin measurement if the coupling between the cantilever vibrations and the spin is small in comparison with the amplitude of the radio-frequency external field.Comment: 16 pages RevTeX including 4 figure