Umbilical disconnect actuator

Contamination of sensitive equipment when squibs are fired is prevented by O-rings which retain the debris of squib discharge within the disconnect device

Developing Water Areas for Outdoor Recreation

Water and recreation go together. Iowa has many potential water recreation areas, including man-made or constructed lakes. The author gives a broad outline for those concerned with recreational development, indicating the many considerations for a sound project down to estimating costs for specific projects

Determination of mean atmospheric densities from the explorer ix satellite

Mean atmospheric densities from changes in orbital elements of Explorer IX satellit

Density And Growth Ring Characteristics Of Pinus Taeda L. Following Thinning

Sixteen experimental plots of loblolly pine (Pinus taeda L.) grown in plantations in Tennessee, USA, were thinned to basal areas of 13.8 m2/ha (heavy), 23.0 m2/ha (moderate), or 32.2 m2/ha (light) in 1963 at age 23. In 1980 12-mm increment cores were removed at breast height, and sections encompassing 8 years before and after thinning were examined for changes in average wood density, radial growth, earlywood and latewood density, and percent latewood. As expected wood density increased with tree age but was not significantly affected by thinning, even though individual tree growth was considerably improved. Although radial growth usually decreases with age, it actually increased in the heavily thinned plots compared to the less severely thinned or unthinned (control) plots. Trees in the moderately and heavily thinned plots produced wood with lower earlywood density and higher latewood density while percent latewood remained unchanged.The timber strength and seasoning characteristics related to wood density should not be affected by thinning. However, the shift within growth rings of earlywood and latewood density distributions may adversely affect pulping qualities of wood

Time-resolved two-dimensional imaging of ground-state species using laser-induced fluorescence

Laser-induced fluorescence has been employed to obtain two-dimensional images of the spatial distribution of a vapor in the ground state with nanosecond resolution. The method has a wide range of potential applications, as it can be used to observe any species which has energy levels accessible to tunable laser systems. In the application we describe, aluminum vapor was observed jetting from spark gap electrodes and diffusing throughout the gap volume

The relational complexity of linear groups acting on subspaces

The relational complexity of a subgroup $G$ of $\mathrm{Sym}(\Omega)$ is a measure of the way in which the orbits of $G$ on $\Omega^k$ for various $k$ determine the original action of $G$. Very few precise values of relational complexity are known. This paper determines the exact relational complexity of all groups lying between $\mathrm{PSL}_{n}(\mathbb{F})$ and $\mathrm{PGL}_{n}(\mathbb{F})$, for an arbitrary field $\mathbb{F}$, acting on the set of $1$-dimensional subspaces of $\mathbb{F}^n$. We also bound the relational complexity of all groups lying between $\mathrm{PSL}_{n}(q)$ and $\mathrm{P}\Gamma\mathrm{L}_{n}(q)$, and generalise these results to the action on $m$-spaces for $m \ge 1$.Comment: 19 page

Mimicking the surface and prebiotic chemistry of early Earth using flow chemistry.

When considering life's aetiology, the first questions that must be addressed are "how?" and "where?" were ostensibly complex molecules, considered necessary for life's beginning, constructed from simpler, more abundant feedstock molecules on primitive Earth. Previously, we have used multiple clues from the prebiotic synthetic requirements of (proto)biomolecules to pinpoint a set of closely related geochemical scenarios that are suggestive of flow and semi-batch chemistries. We now wish to report a multistep, uninterrupted synthesis of a key heterocycle (2-aminooxazole) en route to activated nucleotides starting from highly plausible, prebiotic feedstock molecules under conditions which mimic this scenario. Further consideration of the scenario has uncovered additional pertinent and novel aspects of prebiotic chemistry, which greatly enhance the efficiency and plausibility of the synthesis

Molecular Structure of Polystyrene at Air/Polymer and Solid/Polymer Interfaces

IR-visible sum-frequency generation(SFG) spectroscopy has been used in a total internal reflection geometry to study the molecular structure of polystyrene (PS) at PS/sapphire and PS/air interfaces, simultaneously. The symmetric vibrational modes of the phenyl rings dominate the SFG spectra at the PS/air interface as compared to the antisymmetric vibrational modes at the PS/sapphire interface. This indicates approximately parallel orientation of the phenyl rings at the PS/air interface while nearly perpendicular orientation at the PS/sapphire interface, with respect to the surface normal