Formation and Alteration of Basaltic Soils on Mars

The current surface of Mars is an arid inhospitable environment, dominated by aeolian processes, composed of largely volcanic rocks that have little apparent indication of pervasive aqueous chemical weathering, and blanketed by dust. Rocks are composed of basalts and the “soil” sediments appear to be largely basaltic-derived, and are chemically similar on a global scale. If the climate was once warmer and wetter during the Noachian period, with environmental conditions favorable to the development of life, physically weathered remnants, such as large quantities of phyllosilicate minerals, should remain. Basaltic soils provide a crucial constraint on chemical and physical weathering processes, and are critical for determining the environmental and climatic history of Mars. To understand the origin of sediments, this dissertation investigated the (1) textures of sedimentary grains at Gusev Crater, (2) the chemical and mineral compositions of sediments at the Mars Exploration Rover landing sites in Meridiani Planum and Gusev Crater, and evaluated the potential chemical alteration from weathering, and (3) applied mineral fractionation experiments of analog basalt sediment with implications for interpreting the sorting of sediments on Mars. Textural results indicate that soils are continuously transported and modified by aeolian conditions, and originate primarily from comminuted impacted bedrock. Soil chemical compositions resemble unaltered basalt but mixing of sulfates and phyllosilicates is permissible. Comminuted and grain size sorted basalt analog sediments demonstrate the potential for significant compositional variations imposed by hydrodynamic sorting, an important determinant of soil compositions on Mars. Combined, these results show that soils on Mars are heterogeneous mixtures of comminuted locally derived rocks that have been minimally altered by chemical weathering from olivine dissolution, and are mixed with dust containing older phyllosilicates and sulfates

The clinical applications of cardiogoniometry in cardiovascular disease

Cardiogoniometry (CGM) is a method of 3-dimensional electrocardiographic assessment which has primarily been investigated to evaluate its role in diagnosing patients with suspected coronary artery disease (CAD). Previous work has suggested it has considerable diagnostic ability at identifying patients with both stable CAD and those with acute coronary syndrome (ACS). However, previous studies which investigated the diagnostic performance of CGM in stable CAD did not use robust measures to accurately identify patients with physiologically significant coronary ischaemia. Furthermore, although the ability of CGM to identify specific lesions in stable CAD has been evaluated, to the best of our knowledge no research has been performed to assess the ability of CGM to detect the site of the culprit lesion in patients with non-ST elevation myocardial infarction. The first two studies of this thesis aim to address these two questions about the role of CGM in patients with CAD.Cardiac resynchronisation therapy (CRT) is a treatment used in patients with heart failure and left bundle branch block which attempts to restore synchronous contraction of the ventricles by pacing both the left and right ventricle together. Unfortunately, 25% of patients do not gain a clinical benefit from CRT, such patients are classed as ‘non-responders’. Many methods have been proposed to optimise CRT for ‘non-responders’, however, no specific optimisation method has yet been identified which significantly improves the long term benefit of CRT in non-responders. The detailed spatial and temporal information on cardiac electrical activity that CGM provides suggests that CGM may have a role in the optimisation of CRT. The aim of the third study in this thesis is to evaluate whether CGM can detect changes to CRT pacing settings, in view of developing a method of CRT optimisation using CGM

Election Boycotts and Regime Survival

Election boycotts are a common occurrence in unconsolidated democracies, particularly in the developing world, with prominent examples from recent years occurring in Venezuela, Zimbabwe, and Ethiopia. Despite the frequent occurrence of boycotts, there are few studies available in the scholarly literature concerning the effectiveness of electoral boycotts, particularly as a strategy of opposition parties seeking to bring about the end of electoral authoritarian governments. This paper is based in the democratization literature, with a particular focus on the behavior and vulnerabilities of hybrid or electoral authoritarian regimes. Using an original dataset with global coverage including hybrid regimes from 1981 to 2006, this paper uses event-history analysis to determine the efficacy of boycotts in national elections among other risk factors thought to undermine electoral authoritarian regimes as well as the possibilities for subsequent democratization occurring following both contested and boycotted electoral processes