Tilapia for Biological Control of Giant Salvinia

In August 1999, giant salvinia ( Salvinia molesta Mitchell) was found along the lower Colorado River in irrigation drainages. To investigate the slow spread and apparent control of giant salvinia in this region, the herbivorous fish, tilapia (Oreochromis niloticus Trewavas), was examined as a biological control agent. The study was conducted in a 5,000-L recirculating system. (PDF contains 4 pages.

Growth Patterns and Ages of Trees from Martin Park Nature Center, Oklahoma County, Oklahoma

This paper provides insight into ages and patterns of radial growth from mature trees at Martin Park Nature Center, Oklahoma County, Oklahoma. A total of 80 trees were sampled and crossdated using dendrochronology from the three most common genera at Martin Park Nature Center: Quercus, Celtis, and Ulmus. The oldest trees at the park were Q. macrocarpa and C. laevigata with individuals dating back to the 1920s and 1930s. A pulse of C. laevigata recruitment occurred in the 1960s that likely reflected changes in land-use as the property transitioned from private ownership to the City of Oklahoma City. A sequence of growth suppressions and releases was identified in C. laevigata that is related to park maintenance and forest development at the park

Dendroecology of forests in Missouri : disturbance and integration over multiple centuries

Disturbances are fundamental components of ecological systems which operate at variable frequencies and magnitudes that affect the structures and processes of the system. Multiple disturbance types have functioned in oak (Quercus)-shortleaf pine (Pinus echinata, Mill.) forests including drought, fire, and canopy disturbances that may be natural (wind, ice, insect defoliation) or anthropogenic (logging). To study historic disturbances, dendroecological methods were used to assess the disturbance dynamics across multiple sites in the Missouri Ozarks in order to better understand multiple disturbances and disturbance integration. Increment cores and remnant wood were collected and ring-widths were measured to analyze the patterns of radial growth, used to identify historic disturbances. Growth release analysis (a proxy for canopy disturbance) indicated that species responded to gap openings (1-4 releases), but some trees did not exhibit a growth release suggesting these trees established in large gaps and reached the canopy without a release. An assessment of canopy accession strategies indicated the two most common strategies to reach the canopy were gap origin-no release and gap origin-major release. While some trees did not release, others established in gaps, were subsequently overtopped by adjacent canopy trees and required additional gap openings to reach the canopy. Significant associations (p<0.05) were detected using superposed epoch analysis between drought and fire, drought and growth release, and fire and growth release. This possibly indicates antecedent effects of disturbance. Further analysis of radial growth following fire years showed significant (p<0.05) increases in growth and release events within three years of a fire. However, there were fire years that resulted in significant (p<0.05) decreasing radial growth and no release events that may indicate a severe fire that injured trees. This research demonstrates that frequent, mixed-severity disturbances functioned in promoting the recruitment a

Presidential illness and disability: the health and performance of presidents from 1789-1901

Title from PDF of title page, viewed on July 9, 2014Thesis advisor: Max J. SkidmoreVitaIncludes bibliographical references (pages 75-76)Thesis (M.A.)--Dept. of Political Science. University of Missouri--Kansas City, 2013Presidential health and performance has been a subject of study by both political scientists and historians, many of whom have examined the health of our nation's presidents. This study of presidential history is not new. Many monographs and articles have examined this subject in great detail. While these have led to new interpretations of presidential history, they are inadequate for understanding the problem that presidential ill health and disability have presented during our nation's history. Most studies focus only on the twentieth century and the importance of health into the modern presidency. While the focus of health on the modern presidency has greatly changed our understanding of individual presidents and their effect on history, it nonetheless presents only a partial picture of the problem, since it neglects the effect of presidential health during the early years of the republic. I argue that presidential health has always been of prime importance and its effect is certainly not limited to recent decades. This study will also focus, when appropriate, on the health of the vice president during certain administrations. Many primary source documents, along with various monographs provide great insight into the issue during the early years. The effects of presidential and vice presidential health led to attempted remedies in the nineteenth century, but not until the late twentieth century would they reach fruitio

The politics of opinion assignment: a conditional logit model with varying choice set

"This note replicates and extends Chapter 2 of Forrest Maltzman, James F. Spriggs and Paul J. Wahlbeck's (henceforth: MSW) "Crafting Law on the Supreme Court" (2000). Using a conditional logit model, the authors test the effects of both choice-specific and chooser-specific variables on majority opinion assignment on the United States Supreme Court during Chief Justice Burger's tenure. The authors find that the effect of ideology, as well as other variables, is conditioned on both case facts as well as justices' attributes. In this note, we take issue with the authors' specification of the model, specifically their failure to include choicespecific, i.e. the justices, constants. Below we argue for the statistical necessity of the inclusion of these controls and reassess the original theoretical model with the appropriate statistical specification. We first show that the failure to include these constants will yield biased estimates. We then test if the authors' substantive findings are robust to the correct specification of their original model. While we successfully replicate the original model (yielding biased estimates), we generally find that MSW's core findings, although confirmed, are diminished when correctly estimated." (author's abstract