BILIPROTEINS FROM THE BUTTERFLY Pieris brassicae STUDIED BY TIME-RESOLVED FLUORESCENCE AND COHERENT ANTI-STOKES RAMAN SPECTROSCOPY

The fluorescence decay time of the biliverdin IX7 chromophore present in biliproteins isolated from Pieris brassicae is determined to be 44 ± 3 ps. This value suggests a cyclic helical chromophore structure. The vibrational frequencies determined by CARS-spectroscopy are compared with those of model compounds. The data confirm that the chromophore in the protein-bound state adopts a cyclic-helical, flexible conformation

Excitation Induced Dephasing in Semiconductor Quantum Dots

A quantum kinetic theory is used to compute excitation induced dephasing in semiconductor quantum dots due to the Coulomb interaction with a continuum of states, such as a quantum well or a wetting layer. It is shown that a frequency dependent broadening together with nonlinear resonance shifts are needed for a microscopic explanation of the excitation induced dephasing in such a system, and that excitation induced dephasing for a quantum-dot excitonic resonance is different from quantum-well and bulk excitons.Comment: 6 pages, 4 figures. Extensively revised text, two figures change

Electron spin relaxation in n-type InAs quantum wires

We investigate the electron spin relaxation of $n$-type InAs quantum wires by numerically solving the fully microscopic kinetic spin Bloch equations with the relevant scattering explicitly included. We find that the quantum-wire size and the growth direction influence the spin relaxation time by modulating the spin-orbit coupling. Due to inter-subband scattering in connection with the spin-orbit interaction, spin-relaxation in quantum wires can show different characteristics from those in bulk or quantum wells and can be effectively manipulated by various means.Comment: 8 pages, 6 figure

Small Engine Component Technology (SECT) study. Program report

The study was conducted to identify high payoff technologies for year 2000 small gas turbine applications and to provide a technology plan for guiding future research and technology efforts. A regenerative cycle turboprop engine was selected for a 19 passenger commuter aircraft application. A series of engines incorporating eight levels of advanced technologies were studied and their impact on aircraft performance was evaluated. The study indicated a potential reduction in fuel burn of 38.3 percent. At $1.00 per gallon fuel price, a potential DOC benefit of 12.5 percent would be achieved. At$2.00 per gallon, the potential DOC benefit would increase to 17.0 percent. Four advanced technologies are recommended and appropriate research and technology programs were established to reach the year 2000 goals

Hall effect in laser ablated Co_2(Mn,Fe)Si thin films

Pulsed laser deposition was employed to grow thin films of the Heusler compounds Co_2MnSi and Co_2FeSi. Epitaxial growth was realized both directly on MgO (100) and on a Cr or Fe buffer layer. Structural analysis by x-ray and electron diffraction shows for both materials the ordered L2_1 structure. Bulk magnetization was determined with a SQUID magnetometer. The values agree with the Slater-Pauling rule for half-metallic Heusler compounds. On the films grown directly on the substrate measurements of the Hall effect have been performed. The normal Hall effect is nearly temperature independent and points towards a compensated Fermi surface. The anomalous contribution is found to be dominated by skew scattering. A remarkable sign change of both normal and anomalous Hall coefficients is observed on changing the valence electron count from 29 (Mn) to 30 (Fe).Comment: 9 pages, 6 figures submitted to J Phys

A hybrid computer study of a dynamic ship positioning system

Hybrid computer program for dynamic ship positioning syste

Nearby Gas-Rich Low Surface Brightness Galaxies

We examine the Fisher-Tully cz<1000 km/s galaxy sample to determine whether it is a complete and representative sample of all galaxy types, including low surface brightness populations, as has been recently claimed. We find that the sample is progressively more incomplete for galaxies with (1) smaller physical diameters at a fixed isophote and (2) lower HI masses. This is likely to lead to a significant undercounting of nearby gas-rich low surface brightness galaxies. However, through comparisons to other samples we can understand how the nearby galaxy counts need to be corrected, and we see some indications of environmental effects that probably result from the local high density of galaxies.Comment: 12 page, 2 figures, to appear in Ap

Novel structural features of the ripple phase of phospholipids

We have calculated the electron density maps of the ripple phase of dimyristoylphosphatidylcholine (DMPC) and palmitoyl-oleoyl phosphatidylcholine (POPC) multibilayers at different temperatures and fixed relative humidity. Our analysis establishes, for the first time, the existence of an average tilt of the hydrocarbon chains of the lipid molecules along the direction of the ripple wave vector, which we believe is responsible for the occurrence of asymmetric ripples in these systems

Conventional engine technology. Volume 2: Status of diesel engine technology

The engines of diesel cars marketed in the United States were examined. Prominent design features, performance characteristics, fuel economy and emissions data were compared. Specific problems, in particular those of NO and smoke emissions, the effects of increasing dieselization on diesel fuel price and availability, current R&D work and advanced diesel concepts are discussed. Diesel cars currently have a fuel economy advantage over gasoline engine powered cars. Diesel drawbacks (noise and odor) were reduced to a less objectionable level. An equivalent gasoline engine driveability was obtained with turbocharging. Diesel manufacturers see a growth in the diesel market for the next ten years. Uncertainties regarding future emission regulation may inhibit future diesel production investments. With spark ignition engine technology advancing in the direction of high compression ratios, the fuel economy advantages of the diesel car is expected to diminish. To return its fuel economy lead, the diesel's potential for future improvement must be used