Panspermia, Past and Present: Astrophysical and Biophysical Conditions for the Dissemination of Life in Space

Astronomically, there are viable mechanisms for distributing organic material throughout the Milky Way. Biologically, the destructive effects of ultraviolet light and cosmic rays means that the majority of organisms arrive broken and dead on a new world. The likelihood of conventional forms of panspermia must therefore be considered low. However, the information content of dam-aged biological molecules might serve to seed new life (necropanspermia).Comment: Accepted for publication in Space Science Review

Employment Growth, Worker Mobility, and Rural Economic Development

A county-level labor market model is estimated for North Carolina. The model accounts for inter-county commuting, migration, and within-county adjustments to labor demand shocks. Econometric results indicate that most employment growth (70–80%) during the 1980s was accommodated by changes in commuting flows. Evidence is also presented indicating that labor force growth—and, by extension, population growth and associated fiscal impacts—in rural counties is sensitive to employment growth in nearby urban counties. These results highlight two opposing forces related to spatial spillovers that are usually neglected in analyses of the economic and fiscal impacts of employment growth. Copyright 2003, Oxford University Press.

The thermal alteration by pyrolysis of the organic component of small projectiles of mudrock during capture at hypervelocity

In a series of experiments the pyrolytic effects of the heating induced during the hypervelocity impact (HVI) of small projectiles of high TOC mudrock were observed. Impacts at these high speeds (km s−1) release sufficient energy to vaporise metal projectiles, and the temperatures created greatly exceed the pyrolysis temperatures typically employed during laboratory studies of the thermal alteration of sedimentary organic matter. Despite this the organic geochemical analyses of projectiles of Orcadian Laminite impacted into targets of sand and water at hypervelocities provides evidence that the structural backbone of biomarkers has remained intact and that only a comparatively low degree of thermal alteration (pre-oil window) has occurred. While further studies are necessary, it appears that the organic component of a projectile captured at hypervelocity will be a slightly thermally altered sample of its precursor