Analytical and experimental investigation of sidelobe suppression techniques for reflector type spacecraft antenna Final technical report

Near axis sidelobe suppression techniques for circularly polarized reflector type spacecraft antenna

Research on the design of adaptive control systems, volume 1 Final report

Adaptive control systems - combined optimization and adaptive control, analysis-synthesis and passive adaptive systems, learning systems, and measurement adaptive system

Response of single junction GaAs/GaAs and GaAs/Ge solar cells to multiple doses of 1 MeV electrons

A comparison of the radiation tolerance of MOCVD-grown GaAs cells and GaAs/Ge cells was undertaken using 1 MeV electrons. The GaAs/Ge cells are somewhat more tolerant of 1 MeV electron irradiation and more responsive to annealing than are the GaAs/GaAs cells examined in this study. However, both types of cells suffer a greater degradation in efficiency than has been observed in other recent studies. The reason for this is not certain, but it may be associated with an emitter thickness which appears to be greater than desired. The deep level transient spectroscopy (DLTS) spectra following irradiation are not significantly different for the GaAs/Ge and the GaAs/GaAs cells, with each having just two peaks. The annealing behavior of these peaks is also similar in the two samples examined. It appears that no penalty in radiation tolerance, and perhaps some benefit, is associated with fabricating MOCVD GaAs cells on Ge substrates rather than GaAs substrates

A gephyrin-related mechanism restraining glycine receptor anchoring at GABAergic synapses

Spinal cord neurons release glycine and GABA and accumulate glycine receptors (GlyRs) and GABA(A) receptors in the same postsynaptic densities. In contrast, supramedullar neurons prefer GABA as a neurotransmitter and exclude GlyRs from postsynaptic anchoring. The general aim of the present study was to elucidate the mechanisms underlying transmitter-appropriate receptor accumulation at inhibitory synapses. Specifically, we intended to clarify the molecular basis for the prohibition of GlyR accumulation in the postsynaptic densities of GABAergic synapses. A green fluorescent protein (GFP)-tagged gephyrin-binding loop of the GlyR beta subunit (GFP::betaL) was used as a surrogate for full-length receptors to characterize the GlyR binding capacity of postsynaptic gephyrins in transfected neurons. Both in spinal cord neurons (SCNs) and hippocampal neurons (HNs) GFP::betaL distribution displayed transmitter specificity; i.e., postsynaptic accumulation of GFP::betaL was high opposite terminals able to release glycine and low opposite purely GABAergic terminals. When comparing SCN and HN cultures we found that the level of mRNA coding for gephyrin splice variants containing the cassette C5 (C5-gephyrins) was significantly higher in HNs. In HNs depleted of C5-gephyrins, both GFP::betaL and endogenous GlyRs accumulated at postsynaptic GABAergic sites. Accordingly in SCNs, GFP-tagged C5-gephyrin displayed a preferential postsynaptic accumulation opposite GABAergic synapses. Comparison of glycinergic, mixed, and GABAergic synapses in SCNs showed that the degree of GlyR accumulation was inversely related to the amount of postsynaptic C5-gephyrin. These results identify the C5 splice variant of gephyrin as a factor regulating the transmitter-appropriate degree of GlyR accumulation at inhibitory synapses

Large-area sheet task advanced dendritic web growth development

The computer code for calculating web temperature distribution was expanded to provide a graphics output in addition to numerical and punch card output. The new code was used to examine various modifications of the J419 configuration and, on the basis of the results, a new growth geometry was designed. Additionally, several mathematically defined temperature profiles were evaluated for the effects of the free boundary (growth front) on the thermal stress generation. Experimental growth runs were made with modified J419 configurations to complement the modeling work. A modified J435 configuration was evaluated

An extreme ultraviolet spectrometer experiment for the Shuttle Get Away Special Program

An extreme ultraviolet (EUV) spectrometer experiment operated successfully during the STS-7 mission in an experiment to measure the global and diurnal variation of the EUV airglow. The spectrometer is an F 3.5 Wadsworth mount with mechanical collimator, a 75 x 75 mm grating, and a bare microchannel plate detector providing a spectral resolution of 7 X FWHM. Read-out of the signal is through discrete channels or resistive anode techniques. The experiment includes a microcomputer, 20 Mbit tape recorder, and a 28V, 40 Ahr silver-zinc battery. It is the first GAS payload to use an opening door. The spectrometer's 0.1 x 4.2 deg field of view is pointed vertically out of the shuttle bay. During the STS-7 flight data were acquired continuously for a period of 5 hours and 37 minutes, providing spectra of the 570 A to 850 A wavelength region of the airglow. Five diurnal cycles of the 584 A emission of neutral helium and the 834 A emission of ionized atomic oxygen were recorded. The experiment also recorded ion events and pressure pulses associated with thruster firings. The experiment is to fly again on Mission 41-F

Hydrogen reliquifier Quarterly report, 27 Sept. - 26 Dec. 1967

Computer analyzed hydrogen reliquefier cycles for selection of optimal cycle, rates, and heat exchanger

Two-qubit Quantum Logic Gate in Molecular Magnets

We proposed a scheme to realize a controlled-NOT quantum logic gate in a dimer of exchange coupled single-molecule magnets, $[\textrm{Mn}_4]_2$. We chosen the ground state and the three low-lying excited states of a dimer in a finite longitudinal magnetic field as the quantum computing bases and introduced a pulsed transverse magnetic field with a special frequency. The pulsed transverse magnetic field induces the transitions between the quantum computing bases so as to realize a controlled-NOT quantum logic gate. The transition rates between the quantum computing bases and between the quantum computing bases and other excited states are evaluated and analyzed.Comment: 7 pages, 2 figure

Silicon dendritic web material

The development of a low cost and reliable contact system for solar cells and the fabrication of several solar cell modules using ultrasonic bonding for the interconnection of cells and ethylene vinyl acetate as the potting material for module encapsulation are examined. The cells in the modules were made from dendritic web silicon. To reduce cost, the electroplated layer of silver was replaced with an electroplated layer of copper. The modules that were fabricated used the evaporated Ti, Pd, Ag and electroplated Cu (TiPdAg/Cu) system. Adherence of Ni to Si is improved if a nickel silicide can be formed by heat treatment. The effectiveness of Ni as a diffusion barrier to Cu and the ease with which nickel silicide is formed is discussed. The fabrication of three modules using dendritic web silicon and employing ultrasonic bonding for interconnecting calls and ethylene vinyl acetate as the potting material is examined