Non-Equilibrium Phase Transitions and Domain Walls

Non-equilibrium phase transitions of a scalar field in an expanding spacetime are discussed. These transitions are shown to lead, for appropriate potential energy functions, to a biased choice of vacuum structure which can be analytically described using percolation theory. The initial domain wall networks, which form between different vacua, are evolved in time by computer simulation and their behavior analyzed. It is shown that, unlike systems in thermal equilibrium, domain walls formed in biased systems persist for only a short time before decaying exponentially away. This result opens the door to a re-analysis of domain walls in cosmology.Comment: uu-encoded postscript file. To appear in proceedings of PASCOS 95, 15 page

KPMG's True Value methodology : a critique of economic reasoning on the value companies create and reduce for society

Purpose: The purpose of this paper is to constructively critiquing KPMG’s “True Value methodology” which seeks to quantify in financial terms the value companies create or reduce for society.Design/ methodology/approach: This paper is based on a review of documents produced by KPMG detailing its methodology and corporate reports in the public domain of the True Value methodology applied in practice. The critique is divided into two sections. The first section reviews KPMGs methodological view of a bounded economic reality and offers potential starting points and limitations for a conceptual framing of the ‘methodology’. Practical insights on applying the methodology are offered in the second section. Findings The True Value methodology helps its producers understand the potential risk to future earnings posed by current externalities being internalised. KPMG’s socio-economic framing of future scenarios and financial valuation of environmental and social impacts is limited to a standardised commercial viewpoint. Potential opportunities exist for producers to involve stakeholders in the application of the methodology to form a more inclusive and pluralist conception of risk and values for social and environmental impacts. Originality/ value A constructive critique of this contemporary, financial practice of accounting for externalities developed by KMPG. Practical implications: Offers timely insights for companies using and considering the use of the “True Value” methodology and stakeholders considering their engagement in the application process and/or use of its findings

Food security : the Athenian grain-tax law of 374/3 BC

This paper examines the translation of the Athenian Grain-Tax Law established in 374/3 BC, the period often referred to as early Classical antiquity. A particular focus is placed on the potential contribution of 'accounting history' as a means of exploring the use of grain tax to ensure food security. In terms of historic interpretations, the Grain-Tax is a relatively new piece of evidence discovered in the Athenian market place excavations of 1986 and, as yet, not known to have been studied within accounting research. Empirical research for this paper took the form of a hermeneutic analysis. The focus of examination was our translation of a Marble Stele inscribed in Greek with the Athenian Grain-Tax Law of 374/3 BC. This included a linguistic translation by the authors taking into account alternative translations of the Grain-Tax from other disciplines and placing the evidence in context through symbolic interpretations of other artifacts of the time based on fieldwork research. Emphasis was placed on the method of accounting for tax collection depicted by the Grain-Tax. Our interpretation of the tax highlights the challenges of researching the interchangeable nature of grain and coinage as a 'currency' for payment including aspects of measurability alongside accountability and the potential implications of this for the use of the tax system as a means of ensuring food security. Drawing new evidence for accounting research from Classical Athens and further exploring the use of hermeneutics within accounting history as a means to increase the scope of what is viewed as evidence in accounting history

Charged Vacuum Bubble Stability

A type of scenario is considered where electrically charged vacuum bubbles, formed from degenerate or nearly degenerate vacuua separated by a thin domain wall, are cosmologically produced due to the breaking of a discrete symmetry, with the bubble charge arising from fermions residing within the domain wall. Stability issues associated with wall tension, fermion gas, and Coulombic effects for such configurations are examined. The stability of a bubble depends upon parameters such as the symmetry breaking scale and the fermion coupling. A dominance of either the Fermi gas or the Coulomb contribution may be realized under certain conditions, depending upon parameter values.Comment: 16 pages,revtex; accepted for publication in Phys.Rev.

Estimating the functional form for the density dependence from life history data

Two contrasting approaches to the analysis of population dynamics are currently popular: demographic approaches where the associations between demographic rates and statistics summarizing the population dynamics are identified; and time series approaches where the associations between population dynamics, population density, and environmental covariates are investigated. In this paper, we develop an approach to combine these methods and apply it to detailed data from Soay sheep (Ovis aries). We examine how density dependence and climate contribute to fluctuations in population size via age- and sex-specific demographic rates, and how fluctuations in demographic structure influence population dynamics. Density dependence contributes most, followed by climatic variation, age structure fluctuations and interactions between density and climate. We then simplify the density-dependent, stochastic, age-structured demographic model and derive a new phenomenological time series which captures the dynamics better than previously selected functions. The simple method we develop has potential to provide substantial insight into the relative contributions of population and individual-level processes to the dynamics of populations in stochastic environments

Using a Grid-Enabled Wireless Sensor Network for Flood Management

Flooding is becoming an increasing problem. As a result there is a need to deploy more sophisticated sensor networks to detect and react to flooding. This paper outlines a demonstration that illustrates our proposed solution to this problem involving embedded wireless hardware, component based middleware and overlay networks

Measuring molecular abundances in comet C/2014 Q2 (Lovejoy) using the APEX telescope

Comet composition provides critical information on the chemical and physical processes that took place during the formation of the Solar system. We report here on millimetre spectroscopic observations of the long-period bright comet C/2014 Q2 (Lovejoy) using the Atacama Pathfinder Experiment (APEX) band 1 receiver between 2015 January UT 16.948 to 18.120, when the comet was at heliocentric distance of 1.30 AU and geocentric distance of 0.53 AU. Bright comets allow for sensitive observations of gaseous volatiles that sublimate in their coma. These observations allowed us to detect HCN, CH3OH (multiple transitions), H2CO and CO, and to measure precise molecular production rates. Additionally, sensitive upper limits were derived on the complex molecules acetaldehyde (CH3CHO) and formamide (NH2CHO) based on the average of the strongest lines in the targeted spectral range to improve the signal-to-noise ratio. Gas production rates are derived using a non-LTE molecular excitation calculation involving collisions with H2O and radiative pumping that becomes important in the outer coma due to solar radiation. We find a depletion of CO in C/2014 Q2 (Lovejoy) with a production rate relative to water of 2 per cent, and relatively low abundances of Q(HCN)/Q(H2O), 0.1 per cent, and Q(H2CO)/Q(H2O), 0.2 per cent. In contrast the CH3OH relative abundance Q(CH3OH)/Q(H2O), 2.2 per cent, is close to the mean value observed in other comets. The measured production rates are consistent with values derived for this object from other facilities at similar wavelengths taking into account the difference in the fields of view. Based on the observed mixing ratios of organic molecules in four bright comets including C/2014 Q2, we find some support for atom addition reactions on cold dust being the origin of some of the molecules.Comment: 10 pages, 7 figures, to be published in MNRA

Magnetic properties of 3d-impurities substituted in GaAs

We have calculated the magnetic properties of substituted 3d-impurities (Cr-Ni) in a GaAs host by means of first principles electronic structure calculations. We provide a novel model explaining the ferromagnetic long rang order of III-V dilute magnetic semiconductors. The origin of the ferromagnetism is shown to be due to delocalized spin-uncompensated As dangling bond electrons. Besides the quantitative prediction of the magnetic moments, our model provides an understanding of the halfmetallicity, and the raise of the critical temperature with the impurity concentration