Solar cell radiation flight experiment Quarterly progress report, 2 Dec. 1968 - 14 Mar. 1969

Design and test data of solar cells selected for flight on ATS-E for radiation effect

Rocket propulsion research at Lewis Research Center

A small contingent of engineers at NASA LeRC pioneered the basic research on liquid propellants for rockets shortly after World War 2. Carried on through the 1950s, this work influenced the important early decisions made by Abe Silverstein when he took charge of the Office of Space Flight Programs for NASA. He strongly supported the development of liquid hydrogen as a propulsion fuel in the face of resistance from Wernher von Braun. Members of the LeRC staff played an important role in bringing liquid hydrogen technology to the point of reliability through their management of the Centaur Program. This paper demonstrates how the personality and engineering intuition of Abe Silverstein shaped the Centaur program and left a lasting imprint on the laboratory research tradition. Many of the current leaders of LeRC received their first hands-on engineering experience when they worked on the Centaur program in the 1960s

The British Geological Survey's new Geomagnetic Data Web Service

Increasing demand within the geomagnetism community for high quality real-time or near-real-time observatory data means there is a requirement for data producers to have a robust and scalable data processing infrastructure capable of delivering geomagnetic data products over the Internet in a variety of formats. We describe a new software system, developed at BGS, which will allow access to our geomagnetic data products both within our organisation's intranet and over the Internet. We demonstrate how the system is designed to afford easy access to the data by a wide range of software clients and allow rapid development of software utilizing our observatory data

Exact Solution of a Jamming Transition: Closed Equations for a Bootstrap Percolation Problem

Jamming, or dynamical arrest, is a transition at which many particles stop moving in a collective manner. In nature it is brought about by, for example, increasing the packing density, changing the interactions between particles, or otherwise restricting the local motion of the elements of the system. The onset of collectivity occurs because, when one particle is blocked, it may lead to the blocking of a neighbor. That particle may then block one of its neighbors, these effects propagating across some typical domain of size named the dynamical correlation length. When this length diverges, the system becomes immobile. Even where it is finite but large the dynamics is dramatically slowed. Such phenomena lead to glasses, gels, and other very long-lived nonequilibrium solids. The bootstrap percolation models are the simplest examples describing these spatio-temporal correlations. We have been able to solve one such model in two dimensions exactly, exhibiting the precise evolution of the jamming correlations on approach to arrest. We believe that the nature of these correlations and the method we devise to solve the problem are quite general. Both should be of considerable help in further developing this field.Comment: 17 pages, 4 figure

A marker suitable for sex-typing birds from degraded samples

A new primer set was developed for sex-typing birds, Z37B. This primer set was designed to amplify alleles of small size to render it suitable for sex-typing degraded samples, including shed feathers. This marker successfully sex-typed 50 % of the species tested, including passerines, shorebirds, rails, seabirds, eagles and the brown kiwi Apteryx australis (allele size range =81–103 bp), and is therefore expected to be suitable for sex-typing a wide range of species. Z37B sex-typed nondegraded samples (blood), degraded tissue (dead unhatched embryos, dead nestlings and museum specimens) and samples of low quantity DNA (plucked feathers and buccal swabs). The small amplicon sizes in birds suggest that this marker will be of utility for sex-typing feathers, swabs and degraded samples from a wide range of avian species