Assessing clustering methods for exploratory spatial data analysis

Exploratory spatial data analysis continues to be an important area of research. The use and application of clustering methods for the analysis of spatially referenced data is beginning to show some promise. However, a variety of clustering methods does exist. It is essential that a better understanding of these approaches in the geographic domain be pursued in terms of data requirements, computational efficiencies and inherent biases. This paper presents an initial attempt to demonstrate strengths and weaknesses of various clustering approaches for exploratory spatial data analysis.

Spatially Lagged Choropleth Display

Choropleth display of spatial information is a fundamental feature of mapping and geographic information system technologies. There has long been a desire to impart some spatial influence in the class selection and delineation process of choropleth display. This paper presents an approach for representing the spatial influence of neighboring areas in the creation of choropleth classes. The usefulness of this approach is explored using suburb level crime statistics for Brisbane, Australia.

Increasing granular flow rate with obstructions

We describe a simple experiment involving spheres rolling down an inclined plane towards a bottleneck and through a gap. Results of the experiment indicate that flow rate can be increased by placing an obstruction at optimal positions near the bottleneck. We use the experiment to develop a computer simulation using the PhysX physics engine. Simulations confirm the experimental results and we state several considerations necessary to obtain a model that agrees well with experiment. We demonstrate that the model exhibits clogging, intermittent and continuous flow, and that it can be used as a tool for further investigations in granular flow.Comment: 7 pages, 6 figure

The circular economy: An interdisciplinary exploration of the concept and application in a global context

There have long been calls from industry for guidance in implementing strategies for sustainable development. The Circular Economy represents the most recent attempt to conceptualize the integration of economic activity and environmental wellbeing in a sustainable way. This set of ideas has been adopted by China as the basis of their economic development (included in both the 11th and the 12th ‘Five Year Plan’), escalating the concept in minds of western policymakers and NGOs. This paper traces the conceptualisations and origins of the Circular Economy, tracing its meanings, and exploring its antecedents in economics and ecology, and discusses how the Circular Economy has been operationalized in business and policy. The paper finds that while the Circular Economy places emphasis on the redesign of processes and cycling of materials, which may contribute to more sustainable business models, it also encapsulates tensions and limitations. These include an absence of the social dimension inherent in sustainable development that limits its ethical dimensions, and some unintended consequences. This leads us to propose a revised definition of the Circular Economy as “an economic model wherein planning, resourcing, procurement, production and reprocessing are designed and managed, as both process and output, to maximize ecosystem functioning and human well-being”

A modified flood severity assessment for enhanced decision support: application to the Boscastle flash flood of 2004

A modified flash flood severity assessment is presented, based on scoring a set of factors according to their potential for generating extreme catchment-scale flooding. Improvements are made to the index through incorporation of parameter uncertainties, managing data absence, and clearer graphical communication. The motive for proposing these changes is to better inform flood managers during the development of a flash flood that may require an emergency response. This modified decision-support system is demonstrated for the Boscastle flood of 2004 and other historical floods in the United Kingdom. For Boscastle, the extreme nature of the flood is underestimated, which is likely to be due to the lack of sophistication in weighting flood parameters. However, the proposed amendments are able to rapidly reflect the reliability of a catchment severity rating, which may further enhance this technique as a decision-support tool alongside radar observations of localized storms

Index Theory, Gerbes, and Hamiltonian Quantization

We give an Atiyah-Patodi-Singer index theory construction of the bundle of fermionic Fock spaces parametrized by vector potentials in odd space dimensions and prove that this leads in a simple manner to the known Schwinger terms (Faddeev-Mickelsson cocycle) for the gauge group action. We relate the APS construction to the bundle gerbe approach discussed recently by Carey and Murray, including an explicit computation of the Dixmier-Douady class. An advantage of our method is that it can be applied whenever one has a form of the APS theorem at hand, as in the case of fermions in an external gravitational field.Comment: 16 pages, Plain TeX inputting AMSTe

Optimizing public transit quality and system access: the multiple-route, maximal covering/shortest-path problem

Public transit service is a promising travel mode because of its potential to address urban sustainability. However, current ridership of public transit is very low in most urban regions -- particularly those in the United States. Low transit ridership can be attributed to many factors, among which poor service quality is key. Transit service quality may potentially be improved by decreasing the number of service stops, but this would be likely to reduce access coverage. Improving transit service quality while maintaining adequate access coverage is a challenge facing public transit agencies. In this paper we propose a multiple-route, maximal covering/shortest-path model to address the trade-off between public transit service quality and access coverage in an established bus-based transit system. The model is applied to routes in Columbus, Ohio. Results show that it is possible to improve transit service quality by eliminating redundant or underutilized service stops.

The U wave in atrial fibrillation

The U wave in ECGs of patients is difficult to observe because it is hidden under the atrial fibrillatory wave. Measurement and characteristics of the U wave in atrial fibrillation have not previously been described. Beat averaging was used to reveal the U waves in 12-lead ECGs of 8 patients with atrial fibrillation taking account of heart rate dependency of U wave characteristics. U wave polarity and amplitude in 12-lead ECG and the amplitude ratio of U wave to atrial fibrillatory wave in lead VI were measured. U waves were measureable in all patients. U waves were predominantly positive in leads 1. 11. aVF. V2. V3, V4, V5 and V6, negative in leads aVR. Amplitudes were largest in the precordial leads measuring up to 55 fJ V. In lead VI the U wave amplitude was on average 0.17 (range 0.1 to 0.4) times the amplitude of the atrial fibrillatory wave. U waves can be measured by ventricular beat averaging in AF patients. U waves were normal in this small group of patients