Determination of the Hubble Constant Using a Two-Parameter Luminosity Correction for Type Ia Supernovae

In this paper, we make a comprehensive determination of the Hubble constant $H_0$ by using two parameters - the B-V color and the rate of decline $\Delta m_{15}$ - to simultaneously standardize the luminosities of all nearby Cepheid-calibrated type Ia supernovae (SNe Ia) and those of a larger, more distant sample of 29 SNe Ia. Each group is treated in as similar a manner as possible in order to avoid systematic effects. A simultaneous $\chi ^2$ minimization yields a standardized absolute luminosity of the Cepheid-calibrated supernovae as well as the Hubble constant obtained from the more distant sample. We find $H_0 = 62 km/s Mpc^{-1}$ and a standardized absolute magnitude of -19.46. The sensitivity of $H_0$ to a metallicity dependence of the Cepheid-determined distances is investigated. The total uncertainty $\delta H_0$, dominated by uncertainties in the primary Cepheid distance indicator, is estimated to be 5 km/s Mpc^{-1}.Comment: To appear in Ap

The projected impact of inland waterway user charges on grain flows and transport costs in 1990

The Inland Waterway Revenue Act of 1978 (Public Law 95-502) established a surcharge on fuel consumed in the transportation of commodities by commercial inland waterway users. Initiated at four cents per gallon on October 1, 1980 the surcharge is scheduled to increase to ten cents per gallon by the 1985 navigation season. Revenues generated from the user tax have been earmarked to finance the maintenance and operations of existing navigation structures and practices and to defray the cost of current and planned construction. The legislated level of taxation, however, is insufficient to recover the total expenditures associated with these categories. This dissertation considers the impact of various taxation mechanisms designed to recover 100 percent of inland waterway navigation related expenditures;The focus of this study is narrowly defined, in that it is only the impact on shipments of the leading agricultural export commodities--corn, soybeans and wheat--which are considered. The impact of inland waterway user changes on transport costs, origin-destination routing, modal traffic share and modal revenue generated from shipments of grain are estimated utilizing a linear programming model. A solution to the model specifies that combination of corn, soybean and wheat shipments that minimizes the annual transportation costs of shipping grain from U.S. origin-surplus regions to domestic and foreign demand-deficit regions. Results are established upon comparison of a base--no user fee--solution and five user tax solutions. The five user tax types include a fuel tax, segment ton-mile tax, combination fuel segment ton-mile tax, and segment ton-mile tax accompanied by assumed 50 and 100 percent rail rate responses in water competitive regions;The results indicate that the impact on grain shipments is dependent upon the type of tax implemented. Of projected 1989-1990 crop year barge shipments, equal to 2.4 billion bushels, between 10.6 and 17.6 percent are diverted to direct rail or truck shipments. The tax revenue generated from grain shipments ranges from 59.3 to 67.0 million dollars. On a per bushel basis, user charges result in an average increase in barge transportation costs ranging from 3.0 to 3.4 cents per bushel

ECOLOGICAL-ECONOMIC MODELING ON A WATERSHED BASIS: A CASE STUDY OF THE CACHE RIVER OF SOUTHERN ILLINOIS

A digitally represented watershed landscape (ARC/INFO GIS) is merged with farm optimization (linear programming) and sediment and chemical transport (AGNPS) models. Enhanced targeting of non-point source pollution to remedial policy and management initiatives result. The implications of which are linked back to farm income and forward to the managed ecosystem.Environmental Economics and Policy, Research and Development/Tech Change/Emerging Technologies,

Exploring Students\u27 Perceptions of Academically Based Living-Learning Communities

This qualitative study employed focus group interviews to explore students\u27 perceptions of three well established academically based living-learning communities at a large, land-grant university in the Midwest. Three themes emerged that illustrated students\u27 perceptions of a culture that promoted seamless learning, a scholarly environment, and an ethos of relatedness among faculty, staff, and peers. Implications for practice and future research are discussed