A Geographic Study of the Tennessee Central Railway: An East-West Transport Route Across the Cumberland Plateau of Tennessee

The Harriman, Tennessee-Hopkinsville, Kentucky, routeway of the former Tennessee Central Railway is the only east-west rail crossing of the rugged Cumberland Plateau barrier in Tennessee and is one of a very few such rail crossings in the Southern Appalachian plateaus. The railroad\u27s apparent good situation, however, has not resulted in either a large, dependable volume of traffic or a sound financial operation. After years of marginal operations, the Tennessee Central finally ceased operations on August 31, 1968. The line was subsequently divided into three segments and operations are now being conducted by three respective new owners: the Southern Railway, the Louisville and Nashville Railroad, and the Illinois Central Railroad. The purpose of this thesis was to provide a better understanding of this rail route; this material was presented in the form of a geographic-transport analysis of the Tennessee Central Railway, with emphasis being placed upon the plateau-crossing Cumberland section. Specifically, this thesis discussed the historical development, the decline, and the eventual cessation of TC operations; the line of road in terms of both physical and political setting; the rail physical plant and operating procedures; and the TC\u27s function as a freight hauler, including commodity tonnages and composition. Material for this thesis came from four broad source categories: (1) personal interviews with numerous TC employees, (2) the author\u27s personal experiences and observations, (3) Tennessee Central office records, and (4) the secondary sources, which included such valuable references as the Margaret Campbell thesis and the vast amount of material found in the financial and trade publications such as Poor\u27s, Moody\u27s and Railroad Gazette. The Tennessee Central Railway Company was formed on February 1, 1922, but the rail line dates back directly to several predecessor companies and indirectly to the year 1866, the year of the first attempt to connect East and Middle Tennessee by rail. The line continued in operation until August 31, 1968, at which time a lifetime of marginal operations and a more recent history of ever-increasing annual operating deficits finally forced the firm into bankruptcy and thus paved the way for the threefold division of the line among Southern, Louisville and Nashville, and the Illinois Central railroads. As an operating unit the TC\u27s Harriman-Hopkinsville line extended for a distance of approximately 250 miles across Middle and East Tennessee and a portion of southwestern Kentucky and in so doing crossed portions of two major physical divisions of the United States, the Appalachian Highlands and the Interior Plains. The rail line passed through 11 counties in the two-state area and through such cities as Nashville, Clarksville, and Hopkinsville. The greatest barrier to traffic movement over the TC routeway was provided by the eastern and western Cumberland Plateau escarpments and by the western escarpment of the Eastern Highland Rim. The total relief on the line was 1,630 feet--the high point of 2,028 feet above sea level was reached along the Cumberland River west of Nashville. After 1955 the Tennessee Central became a freight-only line. Through service was provided by one train a day in each direction and these were supplemented by several local trains over various portions of the line. As a carrier of traffic the TC as a whole functioned primarily as a traffic terminator. The Cumberland section, on the other hand, served primarily as a traffic originator, the primary originating products being coal from Monterey and limestone products from Crab Orchard. Although the Tennessee Central Railway Company has ceased to exist, the rail line is intact and is currently being operated by three respective new owners. It would appear that the financial strength of these three railroads may be sufficient to improve the competitive position of the Hopkinsville-Harriman line to insure that operations may continue for years to come

The Evolution of Tanning Needs Its Day in the Sun

Variation in human pigmentation has long been an area of interest in biological anthropology, with the advent of genetic technologies allowing deeper plumbing of its evolutionary history. Genome-wide scans of selection show that pigmentation genes have undergone some of the strongest selection in many geographically distant populations. A variety of hypotheses for the photoprotective effects of melanin have been developed, but these hypotheses, as well as genetic studies, focus nearly exclusively on constitutive (basal) pigmentation levels. Failing to consider the contribution of the ultraviolet radiation (UVR) environment neglects the true interface between humans and our environment. Data drawn largely from dermatology demonstrate that constitutive pigmentation and tanning response are weakly coupled in populations from East Asia and the Americas. This suggests a possible role for persistent, UVR-induced pigmentation as a convergent adaptation akin to the protective effect of constitutive pigmentation. The adaptive potential of tanned skin, particularly in the Americas, where constitutive pigmentation is lower than expected, may fill in an important gap in our understanding of the evolution of skin color

First International Conference on Laboratory Research for Planetary Atmospheres

Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices

Spiral Structure Based Limits on the Disk Mass of the Low Surface Brightness Galaxies UGC 6614 and F568-6

Upper limits for the disk mass-to-light ratios for the low surface brightness galaxies UGC 6614 and F568-6 (Malin 2) are estimated by considering the minimum velocity perturbations in the HI velocity field that should result from the spiral structure observed in the R band images. The weak observed response in the $\phi$ velocity component limits the mass-to-light ratios of the disk within a scale length to M/L <~ 3 and 6 for UGC 6614 for F568-6 respectively (in solar units) based upon azimuthal variations observed in the R band images. These limits are sufficiently strong to require a significant dark matter component even in the central regions of these galaxies. Our limits furthermore imply that this dark matter component cannot be in the form of a cold disk since a cold disk would necessarily be involved in the spiral structure. However, a more massive disk could be consistent with the observations because of a non-linear gas response or if the gas is driven by bar-like distortions instead of spiral structure. To produce the large observed arm/interarm HI density variations it is likely that the spiral arm potential perturbation is sufficiently strong to produce shocks in the gas. For a forcing that is greater than 2% of the axisymmetric force, M/L >~ 1 is required in both galaxies in the outer regions. These lower limits imply that the stellar surface density is at least of the same order as the gas surface density. This is consistent with the large scale morphology of the spiral structure, and the stability of the gas disk, both which suggest that a moderate stellar component is required to produce the observed spiral structure. (Shortened abstract)Comment: AAS Latex, Postscript and jpeg Figures, Accepted for publication in A

Rigidification of algebras over multi-sorted theories

We define the notion of a multi-sorted algebraic theory, which is a generalization of an algebraic theory in which the objects are of different "sorts." We prove a rigidification result for simplicial algebras over these theories, showing that there is a Quillen equivalence between a model category structure on the category of strict algebras over a multi-sorted theory and an appropriate model category structure on the category of functors from a multi-sorted theory to the category of simplicial sets. In the latter model structure, the fibrant objects are homotopy algebras over that theory. Our two main examples of strict algebras are operads in the category of simplicial sets and simplicial categories with a given set of objects.Comment: This is the version published by Algebraic & Geometric Topology on 14 November 200

Bar constructions and Quillen homology of modules over operads

We show that topological Quillen homology of algebras and modules over operads in symmetric spectra can be calculated by realizations of simplicial bar constructions. Working with several model category structures, we give a homotopical proof after showing that certain homotopy colimits in algebras and modules over operads can be easily understood. A key result here, which lies at the heart of this paper, is showing that the forgetful functor commutes with certain homotopy colimits. We also prove analogous results for algebras and modules over operads in unbounded chain complexes.Comment: 38 pages, uses xy-pic, minor revisio