Application of Geographical Information Systems to Lahar Hazard Assessment on an Active Volcanic System

Lahars (highly dynamic mixtures of volcanic debris and water) have been responsible for some of the most serious volcanic disasters and have killed tens of thousands of people in recent decades. Despite considerable lahar model development in the sciences, many research tools have proved wholly unsuitable for practical application on an active volcanic system where it is difficult to obtain field measurements. In addition, geographic information systems are tools that offer a great potential to explore, model and map hazards, but are currently under-utilised for lahar hazard assessment. This research pioneered a three-tiered approach to lahar hazard assessment on Montserrat, West Indies. Initially, requirements of potential users of lahar information (scientists and decision-makers) were established through interview and evaluated against attainable modelling outputs (given flow type and data availability). Subsequently, a digital elevation model, fit for modelling lahars, was used by a path of steepest descent algorithm and a semi-empirical debris-flow model in the prediction of lahar routes and inundation areas. Limitations of these established geographical information system (GIS) based models, for predicting the behaviour of (relatively under-studied) dilute lahars, were used to inform key parameters for a novel model, also tightly coupled to a GIS, that simulated flow routes based on change in velocity. Importantly, uncertainty in model predictions was assessed through a stochastic simulation of elevation error. Finally, the practical utility of modelling outputs (visualisations) was assessed through mutual feedback with local scientists. The new model adequately replicated past flow routes and gave preliminary predictions for velocities and travel times, thus providing a short-term lahar hazard assessment. Inundation areas were also mapped using the debris-flow model to assist long-term planning. Ultimately, a GIS can support ‘on the ground’ planning decisions, but efficacy is limited by an active volcanic system which can restrict feedback to and from end-users. *[The appendices for this thesis were submitted as separate files which could not be uploaded to the repository. Please contact the author for more information.]

A tool for assessing error in digital elevation models from a user’s perspective

A Digital Elevation Model (DEM) is a representation of geographic reality. The elevations recorded within DEMs have been shown to contain errors pertaining to sampling, measurement and interpolation (Fisher, 1998). Even a small amount of elevation error can greatly affect derivative products (Holmes et al., 2000). This can potentially have a significant impact on the application of DEMs in Geographical Information Systems (GIS) where first and second order derivatives are considered

Microbial assemblage of the anatomical parts of gercacinid crab from a tropical mangrove swamp

The microbial assemblage and occurrence in the gut, flesh and shell of Cardisoma armatum, from the tropical mangrove swamp of Lagos Lagoon, Nigeria, was analysed using standard microbiological techniques. The crab gut had the highest total heterotrophic bacteria count and total coliform count with respective significant (p<0.05) values of 6.90 ± 0.16 x104CFU g-1 and 3.45 ± 0.12 x102CFU g-1. Total feacal coliform of the crabs were 0.05 ± 0.00 x102CFU g-1, 0.01 ± 0.00 x102Cfu g-1 and 0.01 ± 0.00 x102CFU g-1 in gut, flesh and shell, respectively. Highest total fungal count of 7.50 ± 0.04 x103CFU g-1 was recorded in the crab shell. The bacteria and fungi species isolated and their frequencies of occurrences in percentage were: Bacillus sp. (21.4 %), Citrobacter sp. (3.6 %) Enterobacter sp. (7.1 %), Escherichia coli (10.7 %), Klesiellia pneumonia (17.9 %), Providencia sp. (3.6 %), Serratia sp. (10.7 %), Staphylococcus aureus (10.7 %), S. epidermis (7.1 %), Vibrio sp. (7.1 %), Aspergillus flavus (8.6 %), Aspergillus fumigatu (5.7 %), Aspergillus niger (40.0 %), Fusarium sp. (14.3 %), Penicillium sp. (5.7 %) and Saccharomyces sp. (25.7 %). The isolation rates in the different anatomical sites of the crab follow the order: guts > flesh > shell and shell > flesh > guts for bacterial and fungi infestation respectively. The results of this study showed that the gercacinid crab, C. armatum in the tropical mangrove of Lagos harbours microorganisms including those that are pathogeni

An Origin of Complicated Infrared Spectra of Perfluoroalkyl Compounds Involving a Normal Alkyl Group

Perfluoroalkyl (Rf) compounds containing a normal alkyl group often yield highly complicated infrared (IR) spectra especially in the C–F stretching vibration (νC–F) region. To reveal the reason behind this, the IR p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) is employed to measure a monolayer of CF3(CF2)9(CH2)3COOH deposited on a silicon substrate. The compound is known to spontaneously aggregate to form a molecular assembly with the closest packing, in which the molecules are oriented perpendicular to the substrate. The IR pMAIRS spectra apparently prove that the complexity of the νC–F region is due to the normal alkyl part directly connected to the Rf group because the carbons in the Rf group are vibrated as a coupled oscillator, and the oscillation of the alkyl part propagates to the Rf part along the molecular axis

Extinction of gambling cue-reactivity: A pilot study in a problem gambling treatment setting

Copyright: © Riley BJ (2018). This Article is distributed under the terms of Creative Commons Attribution 4.0 International LicenseClinical interventions which focus on extinction learn-ing have been shown to reduce craving and relapse in substance related and behavioural addictions. This paper reports a small pilot study with 20 problem gamblers re-ferred for treatment by a local court diversion program. We investigated the use of portable heart rate monitors to measure the effectiveness of Cue Exposure Therapy (CET) in extinguishing gambling cue-reactivity. Cue-reactivity pro-cedures consisted of a relaxation period followed by in-vivo exposure with response prevention in a gambling environ-ment. Cue exposure therapy was manualised. Dependent measures comprised both self-report (gambling urge and problem gambling questionnaire) and physiologic measures (heart rate). Significant increases in heart rate were ob-served during in-vivo pre-CET but not post-CET (p < 0.001). Following CET, significant reductions across all dependent variables were observed (p ≤ 0.001) with within-group ef-fect sizes ranging between r = -.55 and -.61. Overall, the results of this small pilot study support the feasibility and acceptability of the use of portable heart rate monitors to observe the extinction of gambling cue-reactivity. Portable heart rate monitors may provide a novel and useful tool for therapists and their problem gambling patients to monitor gambling cue-reactivity during treatment. Further research is needed to evaluate whether extinction of cue-reactivity can reduce problem gambling relapse

Expanding the palette of phenanthridinium cations

5,6-Disubstituted phenanthridinium cations have a range of redox, fluorescence and biological properties. Some properties rely on phenanthridiniums intercalating into DNA, but the use of these cations as exomarkers for the reactive oxygen species (ROS), superoxide, and as inhibitors of acetylcholine esterase (AChE) do not require intercalation. A versatile modular synthesis of 5,6-disubstituted phenanthridiniums that introduces diversity by Suzuki–Miyaura coupling, imine formation and microwave-assisted cyclisation is presented. Computational modelling at the density functional theory (DFT) level reveals that the novel displacement of the aryl halide by an acyclic N-alkylimine proceeds by an SNAr mechanism rather than electrocyclisation. It is found that the displacement of halide is concerted and there is no stable Meisenheimer intermediate, provided the calculations consistently use a polarisable solvent model and a diffuse basis set

Methicillin-resistant Staphylococcus aureus in Community-acquired Skin Infections

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) is the most common pathogen among patients with skin and soft tissue infections seeking treatment at a Los Angeles (USA) area emergency department. The proportion caused by MRSA increased from 29% in 2001 to 2002 to 64% in 2003 to 2004. No clinical or historical features reliably predict MRSA etiology