Implications of HGV charging for the UK

Road transport taxation in Europe is undergoing a major and radical shift away from fixed charges and fuel duties towards pricing according to distance travelled and externalities produced. Implementation is underway in some states, change being led by national schemes for the freight sector only. The UK is considering such a system for implementation by 2008, to use global positioning system technology. The paper reviews the current developments and considers charging scenarios, including a scenario for covering the full external costs of the UK freight industry. Implications for taxation policy are considered, including whether the doctrine of revenue neutrality is consistent with 'sustainable mobility'. Consideration is given to a transition strategy which could bridge between the current level and structure of prices and a future, more economically efficient approach

The Einstein Ring 0047-2808 Revisited: A Bayesian Inversion

In a previous paper, we outlined a new Bayesian method for inferring the properties of extended gravitational lenses, given data in the form of resolved images. This method holds the most promise for optimally extracting information from the observed image, whilst providing reliable uncertainties in all parameters. Here, we apply the method to the well studied optical Einstein ring 0047-2808. Our results are in broad agreement with previous studies, showing that the density profile of the lensing galaxy is aligned within a few degrees of the light profile, and suggesting that the source galaxy (at redshift 3.6) is a binary system, although its size is only of order 1-2 kpc. We also find that the mass of the elliptical lensing galaxy enclosed by the image is (2.91$\pm$0.01)$\times10^{11}$ M_{\sun}. Our method is able to achieve improved resolution for the source reconstructions, although we also find that some of the uncertainties are greater than has been found in previous analyses, due to the inclusion of extra pixels and a more general lens model.Comment: Accepted for publication in Ap

Decomposition of the visible and dark matter in the Einstein ring 0047-2808 by semi-linear inversion

We measure the mass density profile of the lens galaxy in the Einstein ring system 0047-2808 using our semi-linear inversion method developed in an earlier paper. By introducing an adaptively gridded source plane, we are able to eliminate the need for regularisation of the inversion. This removes the problem of a poorly defined number of degrees of freedom, encountered by inversion methods that employ regularisation, and so allows a proper statistical comparison between models. We confirm the results of Wayth et al. (2004), that the source is double, and that a power-law model gives a significantly better fit that the singular isothermal ellipsoid model. We measure a slope alpha=2.11+/-0.04. We find, further, that a dual-component constant M/L baryonic + dark halo model gives a significantly better fit than the power-law model, at the 99.7% confidence level. The inner logarithmic slope of the dark halo profile is found to be 0.87^{+0.69}_{-0.61} (95% CL), consistent with the predictions of CDM simulations of structure formation. We determine an unevolved B-band mass to light ratio for the baryons (only) of 3.05^{+0.53}_{-0.90} h_65 M_sol/L_Bsol (95% CL). This is the first measurement of the baryonic M/L of a single galaxy by purely gravitational lens methods. The baryons account for 65^{+10}_{-18}% (95% CL) of the total projected mass, or, assuming spherical symmetry, 84^{+12}_{-24}% (95% CL) of the total three-dimensional mass within the mean radius of 1.16'' (7.5 h_65^{-1} kpc) traced by the ring. Finally, at the level of >3sigma, we find that the halo mass is rounder than the baryonic distribution and that the two components are offset in orientation from one another.Comment: 17 pages, 5 figures, accepted by ApJ on 17/12/05. This version corrects various typo

Raising the Dead: Clues to Type Ia Supernova Physics from the Remnant 0509-67.5

We present Chandra X-ray observations of the young supernova remnant (SNR) 0509-67.5 in the Large Magellanic Cloud (LMC), believed to be the product of a Type Ia supernova (SN Ia). The remnant is very round in shape, with a distinct clumpy shell-like structure. Our Chandra data reveal the remnant to be rich in silicon, sulfur, and iron. The yields of our fits to the global spectrum confirm that 0509-67.5 is the remnant of an SN Ia and show a clear preference for delayed detonation explosion models for SNe Ia. We study the spectrum of the single brightest isolated knot in the remnant and find that it is enhanced in iron by a factor of roughly two relative to the global remnant abundances. This feature, along with similar knots seen in Tycho's SNR, argues for the presence of modest small-scale composition inhomogeneities in SNe Ia. The presence of both Si and Fe, with abundance ratios that vary from knot to knot, indicates that these came from the transition region between the Si- and Fe-rich zones in the exploded star, possibly as a result of energy input to the ejecta at late times due to the radioactive decay of 56Ni and 56Co. Two cases for the continuum emission from the global spectrum were modeled: one where the continuum is dominated by hydrogen thermal bremsstrahlung radiation; another where the continuum arises from non-thermal synchrotron radiation. The former case requires a relatively large value for the ambient density (~1 cm^-3). Another estimate of the ambient density comes from using the shell structure of the remnant in the context of dynamical models. This requires a much lower value for the density (<0.05 cm^-3) which is more consistent with other evidence known about 0509-67.5. We therefore conclude that the bulk of the continuum emission from 0509-67.5 has a non-thermal origin.Comment: 34 pages, 9 figures (1 color), accepted to ApJ (10 June 2004 issue); correction made to calculation of magnetic field, small sentence change

The Thermal Response of Downhill Skis

AbstractThe temperatures in downhill skies were measured with thermocouples to investigate the heat generation associated with the sliding of skis on snow. In these tests we investigated the effects on ski temperature of the ambient snow temperature, snow type, speed, load and thermal conductivity. A significant temperature rise at the base of the ski was found at the onset of motion in all runs. The temperature rise increased for heavier loads and at lower ambient temperatures. Some ski runs lasted long enough to observe a steady-state temperature at the ski base; it increased with ambient temperature. Longitudinal and transverse temperature variations occurred and were sensitive to snow hardness and skiing technique.We also investigated heat flow through the cross-section of the ski with a finite-element model to determine the effects of ski structure on heat retention at the base. We found that the thermal characteristics as determined by the structure of the ski had a significant effect on the temperature at the ski base. At lower temperatures we expect that friction will be greater in skis which have a large aluminum plate across their base. Steel edges have a lesser effect.</jats:p

A Comparison of Development Times for \u3cem\u3eProtophormia terraenovae\u3c/em\u3e (R-D) Reared on Different Food Substrates

Experiments were conducted to determine whether a specific larval substrate impacted immature development rates. Protophormia terraenovae was raised on beef organs and compared with whole carcasses (rat), to determine if discrepancies in development times were observed. The minimum development time on beef liver was the most consistent with the rat carcass but a significant difference between all substrates was found after the third instar. These differences can be explained by the differences found between heart and muscle and the other substrates. Often length of the larvae is used to estimate insect age and so Day 2 measuring of weight, length, and width of the pupae was undertaken. Significant differences were found for all parameters measured on each of the substrates. As a result, the use of these measurements should not be done for P. terraenovae due to conflicting rearing substrates. Significant differences within substrates were only found for weight of insects developing on heart and length of insects developing on muscle. There was no significant difference in survival from first instar to the adult stage on any of the substrates but personal observation suggested that mortality was higher in insects developing on the brain tissue