Taxation Futures for Sustainable Mobility: final report to the ESRC

The existing transport tax and charging regime has stimulated limited behavioural change and has been politically problematic (as demonstrated by the September 2000 fuel duty protests). This project synthesised a range of research that has explored ways in which road user charging could replace the present regime based on taxing fuels and car ownership. In 2002, when this project was proposed, this was a fringe transport policy issue. Throughout 2003 the subject achieved a sudden prominence, with a government working party being established to explore the possibility of long-term area-wide road user charging. A tax regime change towards a car road user charge for cars has occurred, or is being considered, in societies as contrasting as Oregon State in the USA, the Netherlands, Switzerland and the UK, reflecting a range of policy considerations. For the UK, these include: the ongoing failure of transport policy measures to achieve adequate cuts in congestion and emissions; the success of the London Congestion Charge; the rise in the cost of transport policy interventions; the reduction in Treasury income of eco-reforms to the current tax regime; and the difficulties of, and equity issues relating to, taxing fuel in a future multi-fuel transport sector. The project developed tax change scenarios in conjunction with the project's user group (including policymakers, NGOs and researchers). Five scenarios were modelled using an adaptation of the Dutch Mobility Explorer program. An 'opt-in' transitional policy mechanism involved replacing VED with a small flat-rate kilometre charge for cars of 0.77 p/km. The model suggested it would have little policy impact, but could be used to familiarise car drivers with the concept of a distance charge. A fiscally neutral scenario involved the replacement of VED and Fuel Duty with a banded kilometre charge for cars of between 2.3 and 8.5 p/km (varied by the environmental performance of the vehicle type). This induced little behaviour change, reducing car driver mobility by only 4%. A further scenario, restored the tax revenues lost from post-2000 tax changes, generating an additional £3 billion or £6b per annum. These reduced car driver mobility by 9% - 14%, and total CO2 emissions were predicted to drop by 6% - 9% by 2015, compared to the base scenario. The type of change involved in the revenue-raising scenarios is significant. There would be only a small increase in the use of public transport, with the predominant response being the better utilisation of cars with higher occupancy and more linking of trips to cut distances driven. The project results suggest that road user charging may deliver more revenue stability than fuel taxation. However, clarity is needed over the policy goals – congestion reduction, emission reduction, revenue stability – for a national road user charge, because the goals are not necessarily complementary. It should also be emphasised that a change of tax regime would not remove the need the hard political decisions in this area

Excitons in coupled InAs/InP self-assembled quantum wires

Optical transitions in coupled InAs/InP self-assembled quantum wires are studied within the single-band effective mass approximation including effects due to strain. Both vertically and horizontally coupled quantum wires are investigated and the ground state, excited states and the photoluminescence peak energies are calculated. Where possible we compare with available photo-luminescence data from which it was possible to determine the height of the quantum wires. An anti-crossing of the energy of excited states is found for vertically coupled wires signaling a change of symmetry of the exciton wavefunction. This crossing is the signature of two different coupling regimes.Comment: 8 pages, 8 figures. To appear in Physical Review

Virulence of newcastle disease virus: what is known so far?

In the last decade many studies have been performed on the virulence of Newcastle disease virus (NDV). This is mainly due to the development of reverse genetics systems which made it possible to genetically modify NDV and to investigate the contribution of individual genes and genome regions to its virulence. However, the available information is scattered and a comprehensive overview of the factors and conditions determining NDV virulence is lacking. This review summarises, compares and discusses the available literature and shows that virulence of NDV is a complex trait determined by multiple genetic factors

Confinement and edge effects on atomic collapse in graphene nanoribbons

Atomic collapse in graphene nanoribbons behaves in a fundamentally different way as compared to monolayer graphene, due to the presence of multiple energy bands and the effect of edges. For armchair nanoribbons we find that bound states gradually transform into atomic collapse states with increasing impurity charge. This is very different in zig-zag nanoribbons where multiple quasi-one-dimensional \emph{bound states} are found that originates from the zero energy zig-zag edge states. They are a consequence of the flat band and the electron distribution of these bound states exhibits two peaks. The lowest energy edge state transforms from a bound state into an atomic collapse resonance and shows a distinct relocalization from the edge to the impurity position with increasing impurity charge

On the Geometric Interpretation of the Nonnegative Rank

The nonnegative rank of a nonnegative matrix is the minimum number of nonnegative rank-one factors needed to reconstruct it exactly. The problem of determining this rank and computing the corresponding nonnegative factors is difficult; however it has many potential applications, e.g., in data mining, graph theory and computational geometry. In particular, it can be used to characterize the minimal size of any extended reformulation of a given combinatorial optimization program. In this paper, we introduce and study a related quantity, called the restricted nonnegative rank. We show that computing this quantity is equivalent to a problem in polyhedral combinatorics, and fully characterize its computational complexity. This in turn sheds new light on the nonnegative rank problem, and in particular allows us to provide new improved lower bounds based on its geometric interpretation. We apply these results to slack matrices and linear Euclidean distance matrices and obtain counter-examples to two conjectures of Beasly and Laffey, namely we show that the nonnegative rank of linear Euclidean distance matrices is not necessarily equal to their dimension, and that the rank of a matrix is not always greater than the nonnegative rank of its square

Translation of automotive module RF immunity test limits into equivalent IC test limits using S-parameter IC models

A method to translate immunity specifications of automotive modules into equivalent requirements at integrated circuit (IC) level, using linear scattering parameter models of the ICs, is presented. A technique is described to determine S-parameters of ICs by simulations based on back-annotated analog schematics. The simulation results are compared with measurement data obtained using a specially designed test board. As an example, simulation and measurement results are given for the input stage of an automotive sensor interface. A good agreement is obtained from the lowest test frequency up to 1 GHz. Above this value, the measured results seem to be dominated by package effects