Prevention of damage to delicate connectors during mounting of heavy engines for testing

Air-bearing-pad principle, combined with monitoring system of the air-bearing force, prevents damage between electrical and mechanical connectors joining a large engine system to the test stand during remote mating. Pad provides a cushion between engine and test stand

Study of the marine environment of the northern Gulf of California

The author has identified the following significant results. Results of studies of the oceanography of the northern Gulf of California (Mexico) are reported. A remote, instrumented buoy measuring and telemetering oceanographic data by ERTS-1 satellite was designed, constructed, deployed, and tested. Regular cruises by a research ship on a pattern of 47 oceanographic stations collected data which are analyzed and referenced to analysis of ERTS-1 satellite imagery. A thermal dynamic model of current patterns in the northern Gulf of California is proposed. Findings are examined in relation to the model

Water Use Efficiency by Switchgrass Compared to a Native Grass or a Native Grass Alfalfa Mixture

Perennial grass systems are being evaluated as a bioenergy feedstock in the northern Great Plains. Inter-annual and inter-seasonal precipitation variation in this region will require efficient water use to maintain sufficient yield production to support a mature bioenergy industry. Objectives were to evaluate the impact of a May–June (early season) and a July–August (late season) drought on the water use efficiency (WUE), amount of water used, and biomass production in monocultures of switchgrass (Panicum virgatum L.), western wheatgrass (Pascopyrum smithii (Rydb.) Á. Löve), and a western wheatgrass–alfalfa (Medicago sativa L.) mixture using an automated rainout shelter. WUE was strongly driven by biomass accumulation and ranged from 5.6 to 7.4 g biomass mm−1 water for switchgrass to 1.06 to 2.07 g biomass mm−1 water used with western wheatgrass. Timing of water stress affected WUE more in western wheatgrass and the western wheatgrass–alfalfa mixture than switchgrass. Water deficit for the western wheatgrass–alfalfa mixture was 23 % lower than western wheatgrass (P=0.0045) and 31 % lower than switchgrass (P\u3c0.0001) under the May–June stress water treatment, while switchgrass had a 37 and 38%greater water deficit than did western wheatgrass or western wheatgrass–alfalfa mixture, respectively (P\u3c0.001) under the July–August water stress treatment. Water depletion was always greatest in the upper 30 cm. Switchgrass had greater WUE but resulted in greater soil water depletion at the end of the growing season compared to western wheatgrass and a western wheatgrass– alfalfa mixture which may be a concern under multi-year drought conditions

The effect of uniaxial pressure on the magnetic anisotropy of the Mn_{12}-Ac single-molecule magnet

We study the effect of uniaxial pressure on the magnetic hysteresis loops of the single-molecule magnet Mn_{12}-Ac. We find that the application of pressure along the easy axis increases the fields at which quantum tunneling of magnetization occurs. The observations are attributed to an increase in the molecule's magnetic anisotropy constant D of 0.142(1)%/kbar. The increase in D produces a small, but measurable increase in the effective energy barrier for magnetization reversal. Density-functional theory calculations also predict an increase in the barrier with applied pressure.Comment: version accepted by EPL; 6 pages, including 7 figures. Small changes and added reference

Row Spacing and Productivity of Russian Wild Rye Pastures in Semiarid Environments

To sustain forage yields in dry years in semiarid climates, row spacings \u3e59cm have been recommended for Russian wild rye [Psathyrostachys juncea (Fisch.) Nevski] (Lawrence & Heinrichs, 1968). However, wide row spacings promote weed invasion, soil erosion, and elevated plant crowns resulting in a rough, washboard ground surface (Kilcher, 1961). Jefferson and Kielly (1998) suggested a 30-cm row spacing for optimum sustainable forage yields in Russian wild rye in the semiarid prairie region of Canada. This study aimed to evaluate the relationship between row spacing and productivity of Russian wild rye at two semiarid sites near Mandan, in the northern Great Plains region of the USA (46º 48\u27 N latitude, 100º 55\u27 W longitude)

Dip coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

To date, an experimental dip-coating facility was constructed. Using this facility, relatively thin (1 mm) mullite and alumina substrates were successfully dip-coated with 2.5 - 3.0 ohm-cm, p-type silicon with areas of approximately 20 sq cm. The thickness and grain size of these coatings are influenced by the temperature of the melt and the rate at which the substrate is pulled from the melt. One mullite substrate had dendrite-like crystallites of the order of 1 mm wide and 1 to 2 cm long. Their axes were aligned along the direction of pulling. A large variety of substrate materials were purchased or developed enabling the program to commence a substrate definition evaluation. Due to the insulating nature of the substrate, the bottom layer of the p-n junction may have to be made via the top surface. The feasibility of accomplishing this was demonstrated using single crystal wafers

An Estradiol-Inducible Promoter Enables Fast, Graduated Control of Gene Expression in Fission Yeast [preprint]

The fission yeast Schizosaccharomyces pombe lacks a diverse toolkit of inducible promoters for experimental manipulation. Available inducible promoters suffer from slow induction kinetics, limited control of expression levels and/or a requirement for defined growth medium. In particular, no S. pombe inducible promoter systems exhibit a linear dose response, which would allow expression to be tuned to specific levels. We have adapted a fast, orthogonal promoter system with a large dynamic range and a linear dose response, based on β-estradiol-regulated function of the human estrogen receptor, for use in S. pombe. We show that this promoter system, termed Z3EV, turns on quickly, can reach a maximal induction of 20 fold, and exhibits a linear dose response over its entire induction range, with few off target effects. We demonstrate the utility of this system by regulating the mitotic inhibitor Wee1 to create a strain in which cell size is regulated by β-estradiol concentration. This promoter system will be of great utility for experimentally regulating gene expression in fission yeast

Optical Transparency Using Interference Between Two Modes of a Cavity

In electromagnetically-induced transparency (EIT), the absorption of a probe beam is greatly reduced due to destructive interference between two dressed atomic states produced by a strong laser beam. Here we show that a similar reduction in the single-photon absorption rate can be achieved by tuning a probe beam to be halfway between the resonant frequencies of two modes of a cavity. This technique is expected to be useful in enhancing two-photon absorption while reducing losses due to single-photon scattering.Comment: 4 pages, 5 figure

Millimeter-wave photoresponse due to excitation of two-dimensional plasmons in InGaAs/InP high-electron-mobility transistors

A polarized photoresponse to mm-wave radiation over the frequency range of 40 to 108 GHz is demonstrated in a grating-gated high electron mobility transistor (HEMT) formed by an InGaAs/InP heterostructure. The photoresponse is observed within the plasmon resonance absorption band of the HEMT, whose gate consists of a 9 mu m period grating that couples incident radiation to plasmons in the 2D electron gas. Gate-bias changes the channel carrier concentration, causing a corresponding change in photoresponse in agreement with theoretical expectations for the shift in the plasmon resonance band. The noise equivalent power is estimated to be 235 pW/Hz(1/2)