Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components Quarterly progress report, Jul. 1 - Sep. 30, 1968

Dry heat inactivation of bacterial spores and influence of spore moisture content on z values as related to spacecraft sanitatio

High-temperature thermionic emission microscope

Thermionic emission microscope was designed to operate with metal specimen cathode temperatures of 2000 degrees C

An Exploratory Investigation of the Fundamental Determinants of National Equity Market Returns

This paper studies average and conditional expected returns in national equity markets, and their relation to a number of fundamental country attributes. The attributes are organized into three groups. The first is relative valuation ratios, such as price-to-book-value, cash-flow, earnings and dividends. The second group measures relative economic performance and the third measures industry structure. We find that average returns across countries are related to the volatility of their price-to-book ratios. Predictable variation in returns is also related to relative gross domestic product, interest rate levels and dividend-price ratios. We explore the hypothesis that cross-sectional variation in the country attributes proxy for variation in the sensitivity of national markets to global measures of economic risks. We test single-factor and two-factor models in which countries' conditional betas are assumed to be functions of the more important fundamental attributes.

Conditioning Variables and the Cross-Section of Stock Returns

Previous studies have identified predetermined variables that have some power to explain the time series of stock and bond returns. This paper shows that loadings on the same variables also provide significant cross-sectional explanatory power for stock portfolio returns. These loadings are important, over and the above the variables advocated by Fama and French (1993) in their three factor model,' and also the four factors of Elton, Gruber and Blake (1995). The explanatory power of the loadings on lagged variables is robust to various portfolio grouping procedures and other considerations. The lagged variables reveal information about the cross-section of expected returns that is not captured by popular asset pricing factors. These results carry implications for risk analysis, performance measurement, cost-of-capital calculations and other applications.

Sources of Risk and Expected Returns in Global Equity Markets

This paper empirically examines multifactor asset pricing models for the returns and expected returns on eighteen national equity markets. The factors are chosen to measure global economic risks. Although previous studies do not reject the unconditional mean- variance efficiency of a world market portfolio, our evidence indicates that the tests are low in power, and the world market betas do not provide a good explanation of cross-sectional differences in average returns. Multiple beta models provide an improved explanation of the equity returns.

Contour measurement system

A measurement system for measuring the departures from a straight line of discrete track sections of a track along a coal face in a mine employing a vehicle having a pair of spaced wheel assemblies which align with the track is presented. A reference arm pivotally connects between the wheel assemblies, and there is indicating means for measuring the angle of pivot between the arm and each of the wheel assemblies. The length of the device is less than the length of a track section, and thus when one of the wheel assemblies is on one track section and one is on an adjoining track section, the sum of the indicated angles will be indicative of the angle between track sections. Thus, from the length of a track section and angle, the departure of each track section from the line may be calculated

A study of the applicability of nucleation theory to quasi-thermodynamic transitions of second and higher Ehrenfest-order

The applicability of classical nucleation theory to second (and higher) order thermodynamic transitions in the Ehrenfest sense has been investigated and expressions have been derived upon which the qualitative and quantitative success of the basic approach must ultimately depend. The expressions describe the effect of temperature undercooling, hydrostatic pressure, and tensile stress upon the critical parameters, the critical nucleus size, and critical free energy barrier, for nucleation in a thermodynamic transition of any general order. These expressions are then specialized for the case of first and second order transitions. The expressions for the case of undercooling are then used in conjunction with literature data to estimate values for the critical quantities in a system undergoing a pseudo-second order transition (the glass transition in polystyrene). Methods of estimating the interfacial energy gamma in systems undergoing a first and second order transition are also discussed

A technology development program for large space antennas

The design and application of the offset wrap rib and the maypole (hoop/column) antenna configurations are described. The NASA mission model that generically categorizes the classes of user requirements, as well as the methods used to determine critical technologies and requirements are discussed. Performance estimates for the mesh deployable antenna selected for development are presented

Self-recording portable soil penetrometer

A lightweight portable penetrometer for testing soil characteristics is described. The penetrometer is composed of a handle, data recording, and probe components detachably joined together. The data recording component has an easily removed recording drum which rotates according to the downward force applied on the handle, and a stylus means for marking the drum along its height according to the penetration depth of probe into the soil