American Intervention in Nicaragua, 1848-1861

In the decade following the Mexican War, Nicaragua became one of the focal points for American expansion. Manifest Destiny, commercial interests, the spirit of adventure, and the desire for a transit route--preferably a canal--across the Central American Isthmus all contributed to the attraction this small Central American state had for official and unofficial American expansionist sentiment. The first efforts to establish a viable transit route through Nicaragua were made by Cornelius Vanderbilt who signed a treaty with the Nicaraguan government in 1849 calling for both the establishment of a land crossing and the construction of a canal. Later Vanderbilt reorganized his enterprise into three separate companies: the Vanderbilt Steamship Line to carry passengers from American ports to those in Nicaragua, the Accessory Transit Company to transport passengers across the Isthmus, and the American Atlantic and Pacific Ship Canal Company to build the canal. For financial and technical reasons, the canal construction was never undertaken. Nonetheless, a land and water transit across Nicaragua was functioning smoothly by 1855. Before that time, however, Vanderbilt\u27s control of the transit company had been challenged by former colleagues, and this dispute was never definitively resolved. A soldier of fortune, William Walker of Tennessee, took advantage of the Liberal-Conservative civil war raging in Nicaragua in 1855 to make himself temporary master of that nation. He was finally dislodged in 1857 by Nicaraguan dissidents and the combined forces of the other four Central American republics, along with the intervention of the United States Navy. Also in 1855, Henry L. Kinney of Texas took a group of American colonists to Nicaragua to settle a portion of the Caribbean coast which he purportedly had purchased. Encountering the enmity of Walker, Nicaragua, Great Britain, and the United States Department of State, the colony foundered and died within a few months. Throughout the period, the United States government attempted to maintain a correct diplomatic posture toward Nicaragua and the other Central American states, blunt British commercial and imperialistic thrusts in the region, and restrict illegal activities of its own citizens while trying to protect their legitimate rights and interests. The State Department underwent severe frustration, having been unable to conclude a satisfactory treaty of friendship and commerce with Nicaragua during the entire decade. With the onset of the Civil War in 1861, American attention was diverted from the Isthmus, not to be renewed until the end of the century. For its part, Nicaragua emerged from the period with an increased sensitivity toward foreign intervention or entanglements, and with a heightened xenophobia directed at the United States. The most valuable sources for this study were the New York newspapers, the State Department Archives, and the collected papers and published accounts of some of the participants. Unfortunately, Nicaraguan sources are sparse: the instability of the period, subsequent changes in archival locations, and finally, the 1972 earthquake have combined to make documentary material on the period negligible

Processing and Phase Formation in Zr-Based Bulk-Metallic Glass-Forming Alloys

Bulk-metallic glasses have established a formidable presence in the scientific community in recent years, due to a number of properties that are uncharacteristic of metallically-bonded materials. One of the fundamental challenges facing researchers in this field is to develop new and improved processing methods with the ultimate goal of facilitating a large-scale industrial integration of the materials. The research described herein is directed toward the pursuit of developing and improving upon the current state-of-the art in the science of bulk-metallic glass processing. A number of research and development projects were undertaken in this pursuit. First, the technology to process bulk-metallic glasses at the University of Tennessee was developed and successfully implemented. Second, bulk-metallic glasses were produced using aerodynamic levitation, which showed an improvement over the accessible cooling rates achievable employing other containerless-processing methods. Third, erbium was found to be a superior dopant to other rare-earth elements to neutralize the oxygen in a Zr-based glass-forming alloy. The alloy was found to form a glass in the presence of up to 16,000-atomic-ppm oxygen by microalloying with Er, with a relatively minor effect on the thermal and mechanical integrity of the materials. Fourth, metastable intermetallic phases were identified in as-cast VIT-105 alloy materials that contained oxygen, using diffraction. The diffraction study included the whole pattern fitting of diffraction from crystalline species in a BMG, an analytical approach that, if existing at all in the literature, is quite rare. Furthermore, this study included a novel approach to fitting diffraction from the glass. Fifth, oxygen-stabilized analogues to intermetallic phases were found in the superheated-liquid state. The presence of Er was found to inhibit surface reoxidation, revealing its mechanism for the neutralization of oxygen. The results were used to propose a model for heterogeneous nucleation and the so-called overheating threshold in the alloy

The surgery obstruction groups of the infinite dihedral group

This paper computes the quadratic Witt groups (the Wall L-groups) of the polynomial ring Z[t] and the integral group ring of the infinite dihedral group, with various involutions. We show that some of these groups are infinite direct sums of cyclic groups of order 2 and 4. The techniques used are quadratic linking forms over Z[t] and Arf invariants.Comment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol8/paper29.abs.htm

Embedding, compression and fiberwise homotopy theory

Given Poincare spaces M and X, we study the possibility of compressing embeddings of M x I in X x I down to embeddings of M in X. This results in a new approach to embedding in the metastable range both in the smooth and Poincare duality categories.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol2/agt-2-15.abs.htm