Engines of Growth: Farm Tractors and Twentieth-Century U.S. Economic Welfare

The role of twentieth-century agricultural mechanization in changing the productivity, employment opportunities, and appearance of rural America has long been appreciated. Less attention has been paid to the impact made by farm tractors, combines, and associated equipment on the standard of living of the U.S. population as a whole. This paper demonstrates, through use of a detailed counterfactual analysis, that mechanization in the production of farm products increased GDP by more than 8.0 percent, using 1954 as a base year. This result suggests that studying individual innovations can significantly increase our understanding of the nature of economic growth.

On the Amplitude of Burst Oscillations in 4U 1636-54: Evidence for Nuclear Powered Pulsars

We present a study of 581 Hz oscillations observed during a thermonuclear X-ray burst from the low mass X-ray binary (LMXB) 4U 1636-54 with the Rossi X-ray Timing Explorer (RXTE). We argue that the combination of large pulsed amplitudes near burst onset and the spectral evidence for localized emission during the rise strongly supports rotational modulation as the mechanism for the oscillations. We discuss how theoretical interpretation of spin modulation amplitudes, pulse profiles and pulse phase spectroscopy can provide constraints on the masses and radii of neutron stars. We also discuss the implication of these findings for the beat frequency models of kHz X-ray variability in LMXB.Comment: AASTEX Latex, 13 pages including 5 figures. Accepted for publication in the Astrophysical Journal Letter

Spin-Tunnel Investigation of a 1/20-Scale Model of the Northrop F-5E Airplane

An investigation has been conducted in the Langley spin tunnel to determine the spin and recovery characteristics of a 1/20-scale model of the Northrop F-5E airplane. The investigation included erect and inverted spins, a range of center-of- gravity locations and moments of inertia, symmetric and asymmetric store loadings, and a determination of the parachute size required for emergency spin recovery. The effects of increased elevator trailing-edge-up deflections, of leading-edge and trailing-edge flap deflections, and of simulating the geometry of large external stores were also determined

Door guard

The door guard of the present invention utilizes an L-shaped bar which binds against the panic bar of the door and against the door frame to prevent the panic bar from being pulled down and thus opening the door. The L-shaped bar has a front and side leg. The front leg has attached to it an upper and lower tab which fits one on either side of the panic bar. The side leg binds against the door frame

Transcriptional repression by ApiAP2 factors is central to chronic toxoplasmosis

Tachyzoite to bradyzoite development in Toxoplasma is marked by major changes in gene expression resulting in a parasite that expresses a new repertoire of surface antigens hidden inside a modified parasitophorous vacuole called the tissue cyst. The factors that control this important life cycle transition are not well understood. Here we describe an important transcriptional repressor mechanism controlling bradyzoite differentiation that operates in the tachyzoite stage. The ApiAP2 factor, AP2IV-4, is a nuclear factor dynamically expressed in late S phase through mitosis/cytokinesis of the tachyzoite cell cycle. Remarkably, deletion of the AP2IV-4 locus resulted in the expression of a subset of bradyzoite-specific proteins in replicating tachyzoites that included tissue cyst wall components BPK1, MCP4, CST1 and the surface antigen SRS9. In the murine animal model, the mis-timing of bradyzoite antigens in tachyzoites lacking AP2IV-4 caused a potent inflammatory monocyte immune response that effectively eliminated this parasite and prevented tissue cyst formation in mouse brain tissue. Altogether, these results indicate that suppression of bradyzoite antigens by AP2IV-4 during acute infection is required for Toxoplasma to successfully establish a chronic infection in the immune-competent host

Common Callings and the Enforcement of Postemployment Covenants in Texas Symposium - Business Tort Litigation.

Abstract Forthcoming

Common Callings and the Enforcement of Postemployment Covenants in Texas Symposium - Business Tort Litigation.

Abstract Forthcoming

MP754: A Literature Review of the Effects of Intensive Forestry on Forest Structure and Plant Community Composition at the Stand and Landscape Levels

The effects of intensive forest management on forest structure and plant community composition are not well documented, particularly with respect to the forests in the Northeast. This review presents a six-part synthesis of the literature. The first section considers the effects of intensive forestry practices within the context of naturally regenerated stands. The second section reviews the changes associated with the planting of conifers in softwood sites, as well as those previously occupied by hardwood and mixed-wood stands. The third examines the impacts of intensive management specifically on bryophytes and lichens. The fourth section discusses changes in dead organic matter components of the stand and the fifth with the impact on tree pests. The final section views the effects of intensive forestry from the landscape-scale perspective and is followed by summary and conclusions. While this paper provides a summary of scientific information, it does not recommend policy or propose how the forest should be managed.https://digitalcommons.library.umaine.edu/aes_miscpubs/1022/thumbnail.jp