Retail gasoline markets as networks

The structure of a gasoline market can be an important element in the pricing choices of its participants. However, structure is often measured only indirectly by, for example, the number of independent sellers, or by seller density. Here we present a more direct and literal way of exploring market structure by representing it as a network. We use the structure of the network to delineate submarkets and present some measures from mathematical sociology which can be used to summarise aspects of network structure for use in further analysis. Although our case study here is in retail gasoline markets, the approach has broader application wherever spatial competition is important

A simple spatial model for Edgeworth cycles

Maskin & Tirole (1998) formalise Edgeworth's (1925) model of a dynamic equilibrium between two players where prices increase sharply and decrease slowly; the Edgeworth Cycle. Here, we present an application of the model, showing how Edgeworth Cycles might arise in a marketplace where spatial competition is important. We illustrate the approach using the example of retail gasoline markets where Edgeworth Cycles have been widely observed

The ACCC's Caltex-Mobil decision: A network view

On December 2nd 2009, the Australian Competition and Consumer Commission (ACCC) announced its intention to oppose the acquisition of Mobil's retail assets by Caltex, based in part on an assessment of adverse competition effects in some local markets. Their assessment was based upon the proportion of sites within each local market that would become controlled by Caltex post-merger. This paper suggests an alternative method foranalysing competitive effects, which formalises local market structure into a network and assesses the position of each outlet in that network

The shape and frequency of Edgeworth price cycles in an Australian retail gasoline market

Gasoline prices in many markets follow a saw-toothed pattern known as an Edgeworth Cycle. Lewis (2009) introduces a novel way of measuring the shape of the cycle, the median change in price, and regresses this against a number of explanatory variables in US markets. Here, we undertake a similar regression analysis, but using data from Perth, Australia, and with a novel measure of market structure as a regressor. We also explore a novel measure, based on spectral analysis, of the use of cycles in a mixed strategy, and the factors which drive this use

Tunable photonic band gaps with coherently driven atoms in optical lattices

Optical lattice loaded with cold atoms can exhibit a tunable photonic band gap for a weak probe field under the conditions of electromagnetically induced transparency. This system possesses a number of advantageous properties, including reduced relaxation of Raman coherence and the associated probe absorption, and simultaneous enhancement of the index modulation and the resulting reflectivity of the medium. This flexible system has a potential to serve as a testbed of various designs for the linear and nonlinear photonic band gap materials at a very low light level and can be employed for realizing deterministic entanglement between weak quantum fields

Urban land, planning and governance systems in Nigeria

The narrative of rapid urbanisation in relation to inadequate planning, governance and management regimes in Nigeria is well-rehearsed. The combination of customary and colonial practices, outdated policies and plans and entrenched attitudes is typically regarded as a problem without clear or universal solutions. The aim of this report is to elucidate the urban land administration and planning debate in the country by examining the issues based on literature review and views of key urban sector stakeholders from six cities obtained through interviews.The historical development of land administration, planning and governance regimes in Nigeria is seen to contribute to the failure of the current development system because of an evolution from two distinct paradigms. This leads to confusion and a lack of engagement with formal systems thereby limiting the potential for well-conceived national and state urban development goals from being realised within cities that are not observing the planning frameworks. Colonial segregational policies have been superseded by a succession of policies that increasingly recognise, but cannot enforce, participation, equity, sustainability and climate change adaptation.Simultaneously, massively-scaled urban development continues under a variety of guises to meet the demand for space for urban accommodation, business and services from a diverse population with huge division between the wealthy and the urban poor. There is a growing need to categorise and understand this diversity of development in order to develop policies that adopt the positive aspects of informal development while pursuing national and state development goals and providing healthy and economically viable urban environments for all.It is shown that new development forms such as new towns, developer-built estates and owner built housing are large factors in the foregoing regard as they are in other sub-Saharan African urban areas. In addition, large scale infrastructural development has also led to ribbon and satellite development that takes advantage of the massive investment in national assets. These development forms are far superior to the slum conditions traditionally associated with the term “informal” and they may benefit from some of the “legal” attributes of formal planned developments such as ownership rights and even locally-prepared plans.The advantages of such developments in the vacuum created by the inadequacies of the formal planning system seem self-evident. However, it is apparent that these developments suffer from deficiencies in the provision of infrastructure and services and may also put an intolerable strain on nearby infrastructure and services designed to cope with the much smaller population anticipated by formal planning. Equally, the increasing commodification of lands especially those delivered through the informal system in the face of rapid urbanisation and rising demand are driving land and rental prices to unsustainable levels and out of the reach of essential key workers and the urban poor. This, coupled with the2tendency for the governance arrangements under the informal system to crumble in the face of urbanisation, could potentially displace people that would be considered entitled under the urban land administration and planning system in Nigeria. Furthermore, lack of formal governance and management of housing developments can place people at risk from unhealthy and overcrowded living conditions. This could also empower unscrupulous land owners and developers to prescribe their own governance and management framework, which may result in exploitation of innocent purchasers.The report also examines recent initiatives at national, state and local levels. It concludes that some initiatives have been met with a measure of success and that these are typified by a flexibility that applies global principles at a local level and that canvas the needs and observes the contexts of local populations

Non-perturbative QCD amplitudes in quenched and eikonal approximations

Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations, physical insights are presented that rely on the newly-discovered property of Effective Locality.Comment: Revised version (28 pages and 1 figure in REVTeX). Follow-up work of Eur. Phys. J. C65, pp. 395-411 (2010), (arXiv:1204.2038 [hep-ph]), and Ann. Phys. 327, pp. 2666-2690 (2012), (arXiv:1203.6137 [hep-ph]

Interactions of CO2 with Formation Waters, Oil and Minerals and CO2 storage at the Weyburn IEA EOR site, Saskatchewan, Canada

The Weyburn oil field in Saskatchewan, Canada, is hosted in Mississippian carbonates and has been subject to injection of CO2 since 2000. A detailed mineralogy study was completed as the basis for modeling of mineral storage of injected CO2. Combining the mineralogy with kinetic reaction path models and water chemistry allows estimates of mineral storage of CO2 over 50 years of injection. These results, combined with estimates of pore volume, solubility of CO2 in oil and saline formation waters, and the initial and final pore volume saturation with respect to oil, saline water and gas/supercritical fluid allow an estimate of CO2 stored in saline water, oil and minerals over 50 years of CO2 injection. Most injected CO2 is stored in oil (6.5•106 to 1.3•107 tonnes), followed closely by storage in supercritical CO2 (7.2•106 tonnes) with saline formation water (1.5 - 2•106 tonnes) and mineral storage (2 - 6•105 tonnes) being the smallest sinks. If the mineral dawsonite forms, as modeling suggests, the majority of CO2 dissolved in oil and salineformation water will be redistributed into minerals over a period of approximately 5000 years. The composition of produced fluids from a baseline sampling program, when compared to produced fluids taken three years after injection commenced, suggest that dawsonite is increasingly stable as pH decreases due to CO2 injection. The results suggest that hydrocarbon reservoirs that contain low gravity oil and little or no initial gas saturation prior to CO2 injection, may store the majority of injected CO2 solubilized in oil, making such reservoirs the preferred targets for combined enhanced oil recovery-CO2 storage projects

Effects of Turbulence, Eccentricity Damping, and Migration Rate on the Capture of Planets into Mean Motion Resonance

Pairs of migrating extrasolar planets often lock into mean motion resonance as they drift inward. This paper studies the convergent migration of giant planets (driven by a circumstellar disk) and determines the probability that they are captured into mean motion resonance. The probability that such planets enter resonance depends on the type of resonance, the migration rate, the eccentricity damping rate, and the amplitude of the turbulent fluctuations. This problem is studied both through direct integrations of the full 3-body problem, and via semi-analytic model equations. In general, the probability of resonance decreases with increasing migration rate, and with increasing levels of turbulence, but increases with eccentricity damping. Previous work has shown that the distributions of orbital elements (eccentricity and semimajor axis) for observed extrasolar planets can be reproduced by migration models with multiple planets. However, these results depend on resonance locking, and this study shows that entry into -- and maintenance of -- mean motion resonance depends sensitively on migration rate, eccentricity damping, and turbulence.Comment: 43 pages including 14 figures; accepted for publication in The Astrophysical Journa