Remote measurements of volcanic gases : applications of open-path Fourier transform infra-red spectroscopy (OP-FTIR) and Correlation spectroscopy (COSPEC)

The composition of volcanic gas plumes depends largely on the chemistry of the degassing magma, the depth of volatile exsolution, and the level of volcanic activity. The ratios between the most common volcanic gases: CO2, H2O, SO2, HCl and HF, as measured at the surface, can be used to provide information on the evolution of the magma body. My research on volcanic gases has centred on the use of open-path Fourier transform IR spectroscopy (Op_FTIR) and correlation spectroscopy (COSPEC). I have also used data collected using other direct and remote-sensing techniques. Remote-sensing techniques rely on the characteristic IR or UV absorbances of natural and/or artificial radiation by different gases. The longer range of these techniques enables the analysis of gases in inaccessible plumes; thus reducing the need for operators to enter hazardous areas. As the instruments do not interact with the analysed gases there is no contamination, condensation or secondary reactions. However, the instruments tend to be heavy, expensive, and complex. Environmental factors can complicate analyses; clouds can dissolve and remove analyte rapidly, and variations in wind speed can result in gas fluxes having high errors. It is also much more difficult to analyse specific gas sources remotely as mixing of gases from different sources can occur. Direct-sampling techniques rely on gases being trapped, dissolved or adsorbed before being analysed by traditional methods, e. g. wet-chemistry, colourimetry, and gas chromatography. The capture of gases is best achieved as close to the source as possible, thus increasing the risk to the operator, and may only be possible during periods of low activity. The physical interaction of gases with instrument and collection vessels can lead to contamination and initiation of secondary reactions. Direct-sampling techniques are labour intensive and thus are capable of only generating a relatively small amount of data compared to the more automated remote-sensing techniques. The suitability of an individual technique therefore depends greatly on: the type of gas to be measured; the location of vent or fumamle; the level of volcanic activity; and the environment in which data are collected. I used OP-FTIR on La Fossa di Vulcano to measure the SO2: HCL mass ratios of gases emitted from the rim and central crater fumaroles, -4.3 - 6.1 and 0.9 - 2.6 respectively. I attributed the higher crater rim gas ratios to the interaction of the gases with shallow hydrothermal reservoirs, causing scrubbing of the more soluble HCl- At Mt. Etna, my OP-FTIR analysis of gases emitted from the central craters showed that, in 1994, SO2: HCl mass ratios were ~4.9 - 5.8. These values lie between those reported for eruptive degassing, >10, and background degassing, 2 fluxes for the 1991 - 1993 Etna eruption showed that variations were generally synchronous; small scale differences relating to the drainage of degassed magma from beneath the summit craters into the eruptive fissure. I also conducted OP-FTIR and COSPEC analyses on Montserrat in June 1996 to show the gas plume to be relatively SO2 poor, with SO2: HCl mass ratios of 4 in volcanic plumes to be made. I have also used HF-SiF4 ratios to estimate gas equilibrium temperatures at La Fossa and Mt. Etna to be ~200°C and ~250 - 290°C respectively. I have also investigated the structural evolution of the Masaya Volcanic Complex. The visible complex has formed over ~1000 years; with average rates of effusion of -0.2 x 106 m3/y, much lower than those required to provide the estimated volume of caldera infill, -2 x 106 m3/y. Historic activity has centred on the twin massifs of Volcán Masaya and Volcán Santiago and is dominated by pit-crater collapses. I propose that the degassing episodes, which occur with no increase in eruptive activity, are related to the convective overturn of magma beneath the craters

Heat transfer with very high free-stream turbulence and streamwise vortices

Results are presented for two experimental programs related to augmentation of heat transfer by complex flow characteristics. In one program, high free stream turbulence (up to 63 percent) was shown to increase the Stanton number by more than a factor of 5, compared with the normally expected value based on x-Reynolds number. These experiments are being conducted in a free-jet facility, near the margins of the jet. To a limited extent, the mean velocity, turbulence intensity, and integral length scale can be separately varied. The results show that scale is a very important factor in determining the augmentation. Detailed studies of the turbulence structure are being carried out using an orthogonal triple hot-wire anemometer equipped with a fourth wire for measuring temperature. The v' component of turbulence appears to be distributed differently from u' or w'. In the second program, the velocity distributions and boundary layer thicknesses associated with a pair of counter-rotating, streamwise vortices were measured. There is a region of considerably thinned boundary layer between the two vortices when they are of approximately the same strength. If one vortex is much stronger than the other, the weaker vortex may be lifted off the surface and absorbed into the stronger

Computing the topology of configuration space

Includes bibliographical references.In this work, an algorithm is developed for generating the connectivity graph for a class of articulated manipulators. The algorithm is based upon the ability to determine whether two distinct obstacles in configuration space intersect. The efficiency of the test which is developed lies in the ability to determine the intersection relation by evaluating the curves which describe the configuration space obstacles at only a small number of points.This work was supported by the National Science Foundation under grant CDR 8803017 to the Engineering Research Center for Intelligent Manufacturing Systems

New Methods for Heterocycle Preparation

This dissertation will describe the development and application of novel methods for heterocycle preparation. The first chapter will outline the development of a titanocene catalyzed epoxide-opening rearrangement to prepare indolines from epoxyanilines. A discussion of the reaction development, along with the substrate scope and limitations will be reported.The second chapter will describe progress toward expanding the scope of aStaudinger/aza-Wittig reaction used to prepare substituted 1,2,4-triazines. This methodology has been applied towards the synthesis of a model system for the DEF rings of the natural product noelaquinone. The challenges associated with the Staudinger/aza-Wittig reaction, and the late-stage oxidation strategy to prepare the DEF rings of the noelaquinone model system will be discussed.The third chapter will describe the importance and general preparation of (E)-alkene peptide isosteres. Using compounds prepared in the UPCMLD and published on PubChem as a reference, we present our ongoing initiative to expand the library of α,β-cyclopropyl-γ-amino acid analogs

Automating journey fare calculation for transport for London

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.Includes bibliographical references (p. 71).This thesis develops a method to automate journey fare calculation for Transport for London. Today, fares for every possible origin-destination station pair within the London Underground are prepared manually based on the zonal fare structure. Multiple feasible paths often exist within the network for a given origin-destination pair, each of which may produce a different journey fare. Thus, manually adjusting journey fares after any alteration of the network or fare structure is a time consuming task for staff and restricts Transport for London's ability to implement changes in fare policy. This approach also lacks transparency from the passenger's perspective. Automating Transport for London's fare calculation requires automating the selection of travel paths. This thesis adapts a label-correcting shortest path algorithm to produce journey paths and fares based on four different selection rules: minimum fare, minimum number of transfers, minimum travel time, and minimum distance. The algorithm operates on a directed graph model of the network. This thesis develops a method to structure the directed graph to capture the network's intricacies. Given a network and fare structure, the modified shortest path algorithm produces all path and fare information for an origin-destination pair in less than one millisecond. Transport for London can then assess the implications of a fare policy change by comparing the existing fares with those generated under each path selection rule. Supplementing these comparisons with historical data provides an estimate of the number of journeys affected and the possible impact on fare revenue. This thesis uses a sample dataset to estimate these impacts.by Joshua J. Maciejewski.S.M

NGC 4102: High Resolution Infrared Observations of a Nuclear Starburst Ring

The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 micron line of [NeII], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 1.5" spatial and 25 km/s spectral, resolution. Combining near-infrared, radio, and the [NeII] data shows that the extinction to the starburst is substantial, more than 2 magnitudes at K band, and that the neon abundance is less than half solar. We find that the star formation in the nuclear region is confined to a rotating ring or disk of 4.3" (~300 pc) diameter, inside the Inner Lindblad Resonance. This region is an intense concentration of mass, with a dynamical mass of ~3 x 10^9 solar masses, and of star formation. The young stars in the ring produce the [NeII] flux reported by Spitzer for the entire galaxy. The mysterious blue component of line emission detected in the near-infrared is also seen in [NeII]; it is not a normal AGN outflow.Comment: submitted to Ap

Pathogens, disease, and the social-ecological resilience of protected areas

It is extremely important for biodiversity conservation that protected areas are resilient to a range of potential future perturbations. One of the least studied influences on protected area resilience is that of disease. We argue that wildlife disease (1) is a social-ecological problem that must be approached from an interdisciplinary perspective; (2) has the potential to lead to changes in the identity of protected areas, possibly transforming them; and (3) interacts with conservation both directly (via impacts on wild animals, livestock, and people) and indirectly (via the public, conservation management, and veterinary responses). We use southern African protected areas as a case study to test a framework for exploring the connections between conservation, endemic disease, and social-ecological resilience. We first define a set of criteria for the social-ecological identity of protected areas. We then use these criteria to explore the potential impacts of selected diseases (foot-and-mouth disease, anthrax, malaria, rabies, rift valley fever, trypanosomiasis, and canine distemper) on protected area resilience. Although endemic diseases may have a number of direct impacts on both wild animals and domestic animals and people, the indirect pathways by which diseases influence social-ecological resilience also emerge as potentially important. The majority of endemic pathogens found in protected areas do not kill large numbers of wild animals or infect many people, and may even play valuable ecological roles; but occasional disease outbreaks and mortalities can have a large impact on public perceptions and disease management, potentially making protected areas unviable in one or more of their stated aims. Neighboring landowners also have a significant impact on park management decisions. The indirect effects triggered by disease in the human social and economic components of protected areas and surrounding landscapes may ultimately have a greater influence on protected area resilience than the direct ecological perturbations caused by disease

Refined physical properties of the HAT-P-13 planetary system

We present photometry of four transits of the planetary system HAT-P-13, obtained using defocussed telescopes. We analyse these, plus nine datasets from the literature, in order to determine the physical properties of the system. The mass and radius of the star are M_A = 1.320 +/- 0.048 +/- 0.039 Msun and R_A = 1.756 +/- 0.043 +/- 0.017 Rsun (statistical and systematic errorbars). We find the equivalent quantities for the transiting planet to be M_b = 0.906 +/- 0.024 +/- 0.018 Mjup and R_b = 1.487 +/- 0.038 +/- 0.015 Rjup, with an equilibrium temperature of 1725 +/- 31 K. Compared to previous results, which were based on much sparser photometric data, we find the star to be more massive and evolved, and the planet to be larger, hotter and more rarefied. The properties of the planet are not matched by standard models of irradiated gas giants. Its large radius anomaly is in line with the observation that the hottest planets are the most inflated, but at odds with the suggestion of inverse proportionality to the [Fe/H] of the parent star. We assemble all available times of transit midpoint and determine a new linear ephemeris. Previous findings of transit timing variations in the HAT-P-13 system are shown to disagree with these measurements, and can be attributed to small-number statistics.Comment: Accepted for publication in MNRAS. 8 pages, 5 tables, 3 figures. The results have been included in the TEPCat catalogue of transiting planets at http://www.astro.keele.ac.uk/~jkt/tepcat

Genetic aetiology of self-harm ideation and behaviour

Family studies have identified a heritable component to self-harm that is partially independent from comorbid psychiatric disorders. However, the genetic aetiology of broad sense (non-suicidal and suicidal) self-harm has not been characterised on the molecular level. In addition, controversy exists about the degree to which suicidal and non-suicidal self-harm share a common genetic aetiology. In the present study, we conduct genome-wide association studies (GWAS) on lifetime self-harm ideation and self-harm behaviour (i.e. any lifetime self-harm act regardless of suicidal intent) using data from the UK Biobank (n > 156,000). We also perform genome wide gene-based tests and characterize the SNP heritability and genetic correlations between these traits. Finally, we test whether polygenic risk scores (PRS) for self-harm ideation and self-harm behaviour predict suicide attempt, suicide thoughts and non-suicidal self-harm (NSSH) in an independent target sample of 8,703 Australian adults. Our GWAS results identified one genome-wide significant locus associated with each of the two phenotypes. SNP heritability (h) estimates were ~10%, and both traits were highly genetically correlated (LDSC r > 0.8). Gene-based tests identified seven genes associated with self-harm ideation and four with self-harm behaviour. Furthermore, in the target sample, PRS for self-harm ideation were significantly associated with suicide thoughts and NSSH, and PRS for self-harm behaviour predicted suicide thoughts and suicide attempt. Follow up regressions identified a shared genetic aetiology between NSSH and suicide thoughts, and between suicide thoughts and suicide attempt. Evidence for shared genetic aetiology between NSSH and suicide attempt was not statistically significant