Nuclear radiation problems, unmanned thermionic reactor ion propulsion spacecraft

A nuclear thermionic reactor as the electric power source for an electric propulsion spacecraft introduces a nuclear radiation environment that affects the spacecraft configuration, the use and location of electrical insulators and the science experiments. The spacecraft is conceptually configured to minimize the nuclear shield weight by: (1) a large length to diameter spacecraft; (2) eliminating piping penetrations through the shield; and (3) using the mercury propellant as gamma shield. Since the alumina material is damaged by the high nuclear radiation environment in the reactor it is desirable to locate the alumina insulator outside the reflector or develop a more radiation resistant insulator

Determination of elevated-temperature fatigue data on refractory alloys in ultra- high vacuum third quarterly report, 1 jan. - 1 apr. 1965

Fatigue data for refractory alloys at elevated temperatures in ultrahigh-vacuum environment

Elevated temperature fatigue of TZC MOLYBDENUM alloy under high frequency and high vacuum conditions

Elevated temperature fatigue of TZC molybdenum alloy determined in high frequency and high vacuum test

Collective polarization exchanges in collisions of photon clouds

The one-loop "vacuum" Heisenberg-Euler coupling of four electromagnetic fields can lead to interesting collective effects in the collision of two photon clouds, on a time scale orders of magnitude faster than one estimates from the cross-section and density. We estimate the characteristic time for macroscopic transformation of positive to negative helicity in clouds that are initially totally polarized and for depolarization of a polarized beam traversing an unpolarized cloud.Comment: Recapitulates much that is in hep-ph/0402127, with new results in the last section, and the first section drastically reduced in view of the previous work of Kotkin and Serbo. Typo corrected in eq. 1

Dendrogeomorphology and high-magnitude snow avalanches: a review and case study

International audienceThe application of the principles of dendrogeomorphology for the dating of high-magnitude snow avalanches is well established in the natural hazards literature. A variety of methodologies are employed by different authors, however, and no standardization currently exists for appropriate sample sizes, the issue of "weighting" certain tree-ring responses as more important than others, or the minimum number of responding trees required in order to infer an avalanche event. We review the literature of dendrogeomorphology as it applies to snow avalanches, and examine the questions of sample size, type of ring reactions dated and weighted, and minimum responses. We present tree-ring data from two avalanche paths in the Rocky Mountains of Montana, USA, from trees uprooted by major snow avalanches in the winter of 2002. These data provide distinct chronologies of past avalanche events, and also illustrate how the critical choice of a minimum Index Number can affect the number of avalanche events in a final chronology based on tree-ring analysis

How Agricultural Economists Increase the Value of Agribusiness Research

Historically, there has been declining cooperation between agribusiness firms and agricultural economists. In new product marketing research, firms' tend to conduct their own analyses, partially due to confidentiality, usually consisting of simple univariate or bivariate statistics such as chi-squared tests of independence. The primary objective of this paper is to demonstrate, through a case study, one way in which agricultural economists can add value to agribusiness firms research. Results from the econometric model offer a richer explanation of consumer behavior and may be more useful to agribusiness firms.Teaching/Communication/Extension/Profession,

Determination of elevated-temperature fatigue data on refractory alloys in ultra-high vacuum Eighth quarterly report, 1 Apr. - 1 Jul. 1966

Fatigue testing of refractory alloys to determine effect of notch geometry on fatigue strengt

An Appraisal of the Potential for Soybeans in the United Kingdom

Soybean is a most important crop worldwide, accounting for 56% of world oilseed production and 69% of world protein meal consumption in 2003 (Soystats, 2004). Since their introduction in the early 1800\u27s, forage soybeans have been grown widely in USA. Used originally as a forage crop, this use largely had been forgotten until Dr T. E. Devine (United States Department of Agriculture, Agricultural Research Service; USDA-ARS) released 4 new forage cultivars. Soybeans potentially offer UK farmers a high quality protein source in a short season and also meet the requirements of supermarket chains to remain GM free. This paper aims to indicate whether soybeans can be grown successfully in the UK

Nuclear Reaction Rates in a Plasma

The problem of determining the effects of the surrounding plasma on nuclear reaction rates in stars is formulated ab initio, using the techniques of quantum statistical mechanics. We derive a result that expresses the complete effects of Coulomb barrier penetration and of the influence of the surrounding plasma in terms of matrix elements of well defined operators. We find that possible "dynamical screening" effects that have been discussed in the literature are absent. The form of our results suggests that an approach that relies on numerical calculations of the correlation functions in a classical Coulomb gas, followed by construction of an effective two body potential and a quantum barrier penetration calculation, will miss physics that is as important as the physics that it includes.Comment: 66 pages, revtex, Errors Fixed, Explanation Adde