Gauge Symmetry and Gravito-Electromagnetism

A tensor description of perturbative Einsteinian gravity about an arbitrary background spacetime is developed. By analogy with the covariant laws of electromagnetism in spacetime, gravito-electromagnetic potentials and fields are defined to emulate electromagnetic gauge transformations under substitutions belonging to the gauge symmetry group of perturbative gravitation. These definitions have the advantage that on a flat background, with the aid of a covariantly constant timelike vector field, a subset of the linearised gravitational field equations can be written in a form that is fully analogous to Maxwell's equations (without awkward factors of 4 and extraneous tensor fields). It is shown how the remaining equations in the perturbed gravitational system restrict the time dependence of solutions to these equations and thereby prohibit the existence of propagating vector fields. The induced gravito-electromagnetic Lorentz force on a test particle is evaluated in terms of these fields together with the torque on a small gyroscope. It is concluded that the analogy of perturbative gravity to Maxwell's description of electromagnetism can be valuable for (quasi-)stationary gravitational phenomena but that the analogy has its limitations.Comment: 29 pages no-fig

Today's pupils tomorrow's engineers! Pedagogy and policy:a UK perspective

Purpose – This paper aims to provide a critical analysis of UK Government policy in respect of recent moves to attract young people into engineering. Drawing together UK and EU policy literature, the paper considers why young people fail to look at engineering positively. Design/methodology/approach – Drawing together UK policy, practitioner and academic-related literature the paper critically considers the various factors influencing young people's decision-making processes in respect of entering the engineering profession. A conceptual framework providing a diagrammatic representation of the “push” and “pull” factors impacting young people at pre-university level is given. Findings – The discussion argues that higher education in general has a responsibility to assist young people overcome negative stereotypical views in respect of engineering education. Universities are in the business of building human capability ethically and sustainably. As such they hold a duty of care towards the next generation. From an engineering education perspective, the major challenge is to present a relevant and sustainable learning experience that will equip students with the necessary skills and competencies for a lifelong career in engineering. This may be achieved by promoting transferable skills and competencies or by the introduction of a capabilities-driven curriculum which brings together generic and engineering skills and abilities. Social implications – In identifying the push/pull factors impacting young people's decisions to study engineering, this paper considers why, at a time of global recession, young people should select to study the required subjects of mathematics, science and technology necessary to study for a degree in engineering. The paper identifies the long-term social benefits of increasing the number of young people studying engineering. Originality/value – In bringing together pedagogy and policy within an engineering framework, the paper adds to current debates in engineering education providing a distinctive look at what seems to be a recurring problem – the failure to attract young people into engineering

Trust and Risk in Games of Partial Information

Games of partial information have been used to explicate Gricean implicature; their solution concept has been murky, however. In this paper, I will develop a simple solution concept that can be used to solve games of partial information, depending on the players\u27 mutual trust and tolerance for risk. In addition, I will develop an approach to non-conventional quantity implicatures that relies on face (Goffman (1967), Brown and Levinson (1987))

Using the Twentieth Century Reanalysis to assess climate variability for the European wind industry

We characterise the long-term variability of European near-surface wind speeds using 142 years of data from the Twentieth Century Reanalysis (20CR), and consider the potential of such long-baseline climate data sets for wind energy applications. The low resolution of the 20CR would severely restrict its use on its own for wind farm site-screening. We therefore perform a simple statistical calibration to link it to the higher-resolution ERA-Interim data set (ERAI), such that the adjusted 20CR data has the same wind speed distribution at each location as ERAI during their common period. Using this corrected 20CR data set, wind speeds and variability are characterised in terms of the long-term mean, standard deviation, and corresponding trends. Many regions of interest show extremely weak trends on century timescales, but contain large multidecadal variability. Since reanalyses such as ERAI are often used to provide the background climatology for wind farm site assessments, but contain only a few decades of data, our results can be used as a way of incorporating decadal-scale wind climate variability into such studies, allowing investment risks for wind farms to be reduced.Comment: 18 pages, plus 4 page supplementary information included here as Appendix D. This is the authors' corrected version, matching the content of the version accepted by Theoretical and Applied Climatolog

Petrological studies of the lavas and associated rocks of the Arthur's Seat volcano

Arthur's Seat is the remains of a dissected Lower Carboniferous volcano, from which were erupted a series of basaltic rocks representative of the province to which it belongs. The rocks occur as lavas, intrusions and tuffs, and include basalts of Dalmeny, Jedburgh, Dunsapie, Craiglockhart and Markle types, in addition to mugearite. The Dunsapie basalts have been subdivided into Normal Dunsapie and Feldspathic Dunsapie types.The volcano has been remapped on a scale of 15 inches to 1 mile, and a few minor departures from the 6- inch Geological Survey map have been recorded. These include changes in the numbering and classification of some of the lavas, an alteration to the position of a fault, and slight adjustment of a vent boundary.The petrographic characters of the various volcanic rocks have been described in detail, with modal and chemical analyses. Particular attention has been given to the augite phenocrysts of Craiglockhart basalt, and a method of cutting serial sections through single crystals has been devised. Evidence indicates that the augites have been corroded, and then have re grown prior to eruption.The parental magma of the volcano was probably of a composition very similar to that of Normal Dunsapie basalt. Markle and Craiglockhart types were produced as complementary differentiates of the parental liquid by a process of gravity differentiation, in which sinking of ferromagnesian crystals, particularly augites, played an important part.The Dalmeny and Jedburgh basalts, which have strong chemical resemblances, probably represent only slightly differentiated parental magma. Some sinking of olivine may have occurred in the pre-eruptive history of these microporphyritic types, and transfer of feldspar components by volatiles and establishment of a composition gradient under gravity may also have had some effect in producing the slight differences in composition which have been noted. The less pyroxenic Dalmeny and Jedburgh rocks are ophitic, and their plagioclase crystals show a well developed flow structure which passes through the ophitic augites. In such cases it is inferred that the augite did not crystallise until a late stage in the crystallisation history of the lava.Concentrations of soda-rich volatiles produced intense albitisation in the# Markle basalts and the mugearites. It is considered that the mugearites of Arthur's Seat initially crystallised as Jedburgh type, and were altered to their present state during the deuteric stage.The magma chamber believed to have underlain the volcano was charged with parental magma at least twice during the period of activity. The first and last eruptions were of Dunsapie basalt; the albitised products appeared at a fairly late stage,(see Table summarising Eruptive History).A macroscopic method of fabric analysis has been evolved, and fabric analyses of representative specimens made. both linear and planar fabrics, and sometimes both, have been shown to occur

Why don’t more people use this drug? Myths, Evidence & Policy

This presentation describes barriers to evidence-based medication development, availability, and use; and introduces some of the scientific tools and approaches, such as comparative effectiveness research, that address these barriers. Context: Medication-assisted treatment for opioid dependence

Investigation into digital audio equaliser systems and the effects of arithmetic and transform errors on performance

Merged with duplicate record 10026.1/2685 on 07.20.2017 by CS (TIS)Discrete-time audio equalisers introduce a variety of undesirable artefacts into audio mixing systems, namely, distortions caused by finite wordlength constraints, frequency response distortion due to coefficient calculation and signal disturbances that arise from real-time coefficient update. An understanding of these artefacts is important in the design of computationally affordable, good quality equalisers. A detailed investigation into these artefacts using various forms of arithmetic, filter frequency response, input excitation and sampling frequencies is described in this thesis. Novel coefficient calculation techniques, based on the matched z-transform (MZT) were developed to minimise filter response distortion and computation for on-line implementation. It was found that MZT-based filter responses can approximate more closely to s-plane filters, than BZTbased filters, with an affordable increase in computation load. Frequency response distortions and prewarping/correction schemes at higher sampling frequencies (96 and 192 kHz) were also assessed. An environment for emulating fractional quantisation in fixed and floating point arithmetic was developed. Various key filter topologies were emulated in fixed and floating point arithmetic using various input stimuli and frequency responses. The work provides detailed objective information and an understanding of the behaviour of key topologies in fixed and floating point arithmetic and the effects of input excitation and sampling frequency. Signal disturbance behaviour in key filter topologies during coefficient update was investigated through the implementation of various coefficient update scenarios. Input stimuli and specific frequency response changes that produce worst-case disturbances were identified, providing an analytical understanding of disturbance behaviour in various topologies. Existing parameter and coefficient interpolation algorithms were implemented and assessed under fihite wordlength arithmetic. The disturbance behaviour of various topologies at higher sampling frequencies was examined. The work contributes to the understanding of artefacts in audio equaliser implementation. The study of artefacts at the sampling frequencies of 48,96 and 192 kHz has implications in the assessment of equaliser performance at higher sampling frequencies.Allen & Heath Limite