In the hyperbolic theory of special relativity is space also hyperbolic?

In the hyperbolic theory of special relativity the space of velocities, the kinematic space, is hyperbolic of radius of negative curvature c the velocity of light. Space itself could be either Euclidean or hyperbolic. Whether space is hyperbolic is an important question for cosmology, philosophy and the axioms of special relativity. This paper considers consequences of it being hyperbolic including an estimate of the deviation from parallelism at terrestrial distances

Oxidation of Columbium-Chromium Alloys at Elevated Temperatures

Screening studies of the oxidation characteristics of binary alloys of columbium (Ref. 1) showed that chromium was an additive element worthy of intensive study. The screening studies showed that chromium additions were especially helpful in decreasing the oxidation rate of columbium at 10000deg C and were somewhat less beneficial at 12000deg C. It is the purpose of this investigation to study the oxidation characteristics of binary columbium-chromium alloys in more detail

Involuntary Retirement and the Resolution of the Retirement-Consumption Puzzle: Evidence from Australia

A substantial body of international research has shown that household expenditure on food and non-durables significantly decreases at the time of retirement -- a finding that is inconsistent with the standard life-cycle model of consumption if retirement is an anticipated event. This fall in expenditure has become known as the `retirement- consumption puzzle.' We analyze rich Australian panel data to assess the Australian evidence on the puzzle. We find strong evidence of a fall in expenditures on groceries, food consumed at home and outside meals with retirement. The observed decline in expenditure is explained by a subset of households experiencing an unanticipated wealth shock, such as a major health event or long-term job loss, at the time of retirement. This finding is corroborated by an analysis of alternative measures of household well-being, including indicators of financial hardship, and self-reported financial and life satisfaction. For the majority of households retirement is anticipated and there is no decline in economic welfare at retirement. However, for an important minority, retirement is `involuntary' and these households experience a marked decline across all indicators of economic well-being.Consumption Smoothing, Household Expenditure, Retirement

An Ordered Tobit Model of Market Participation: Evidence from Kenya and Ethiopia

Do rural households in developing countries make market participation and volume decisions simultaneously or sequentially? This article develops a two-stage econometric model that allows testing between these two competing hypotheses regarding household-level market behavior. The first stage models the household's choice of whether to be a net buyer, autarkic, or a net seller in the market. The second stage models the quantity bought (sold) for net buyers (sellers) based on observable household characteristics. Using household data from Kenya and Ethiopia on livestock markets, we find evidence in favor of sequential decision-making, the welfare implications of which we discuss.Industrial Organization,

COREST: A FORTRAN computer program to analyze paralinear oxidation behavior and its application to chromic oxide forming alloys

A FORTRAN computer program (COREST) was developed to analyze the high-temperature paralinear oxidation behavior of metals. It is based on a mass-balance approach and uses typical gravimetric input data. COREST was applied to predominantly Cr2O3-forming alloys tested isothermally for long times. These alloys behaved paralinearly above 1100 C as a result of simultaneous scale formation and scale vaporization. Output includes the pertinent formation and vaporization constants and kinetic values of interest. COREST also estimates specific sample weight and specific scale weight as a function of time. Most importantly, from a corrosion standpoint, it estimates specific metal loss

Engineering analysis and design of a mechanism to simulate a sonic boom

Mechanism simulating vibrational and acoustic properties of sonic boom

Consistent Nonparametric Tests for Lorenz Dominance

This paper proposes a test for Lorenz dominance. Given independent samples of income or other welfare related variable, we propose a test of the null hypothesis that the Lorenz curve for one population is dominated by the Lorenz curve for a second population. The test statistic is based on the standardized largest difference between the empirical Lorenz curves for the two samples. The test is nonparametric in the sense that no distributional assumptions are made and the test is consistent because it compares the Lorenz curves at all quantiles. We derive the asymptotic distribution of the test statistic under the null hypothesis. Since the limiting distribution of the test statistic is nonstandard, being dependent on the underlying Lorenz curves, we propose the use of two computer based procedures for conducting inference. The first is a simulation method that simulates p-values from an approximation to the underlying limiting distribution of the statistic while the second is based on the nonparametric bootstrap. We examine the performance of the methods in a Monte Carlo study and with a comparison of the income based Lorenz curves for the US and Canada.Lorenz dominance, test consistency, simulation.

Household-Level Livestock Marketing Behavior Among Northern Kenyan and Southern Ethiopian Pastoralists

Pastoralists in East Africa's arid and semi-arid lands (ASAL) regularly confront climatic shocks triggering massive herd die-offs and loss of scarce wealth. On the surface, it appears puzzling that pastoralists do not make extensive use of livestock markets to offload animals when climatic shocks temporarily reduce the carrying capacity of local rangelands, and then use markets to restock their herds when local conditions recover. In recent years, donors and policy makers have begun to hypothesize that investments in livestock marketing systems might quickly pay for themselves through reduced demand for relief aid,by increasing pastoralist marketing responsiveness to temporal variation in range conditions.Marketing,