Comment on "Limits on the Time Variation of the Electromagnetic Fine-Structure Constant in the Low Energy Limit from Absorption Lines in the Spectra of Distant Quasars"

In their Letter [Phys. Rev. Lett. 92, 121302 (2004)] (also [Astron. Astrophys. 417, 853 (2004)]), Srianand et al. analysed optical spectra of heavy-element species in 23 absorption systems along background quasar sight-lines, reporting limits on relative variations in the fine-structure constant: da/a=(-0.06+/-0.06) x 10^{-5}. Here we demonstrate basic flaws in their analysis, using the same data and absorption profile fits, which led to spurious values of da/a and significantly underestimated uncertainties. We conclude that these data and fits offer no stringent test of previous evidence for a varying alpha. In their Reply (arXiv:0711.1742) to this Comment, Srianand et al. state or argue several points regarding their original analysis and our new analysis. We discuss these points here, dismissing all of them because they are demonstrably incorrect or because they rely on a flawed application of simple statistical arguments.Comment: 1+2 pages, 1 EPS figure. Page 1 accepted as PRL Comment on arXiv:astro-ph/0402177 . Further details available in arXiv:astro-ph/0612407 . v2: Added critical discussion of Reply from Srianand et al. (arXiv:0711.1742

Housing and council tax benefits administration in England: a long-term perspective on the performance of the local government delivery system

This paper evaluates the performance of the Council Tax and Housing Benefits Administration Services delivered by local authorities since the current system for the delivery of these benefits was introduced. During this period the performance of local government has been regulated and influenced by four successive national delivery regimes imposed by central governments namely Compulsory Competitive Tendering (CCT); Best Value (BV); Comprehensive Performance Assessments (CPA) and Comprehensive Area Assessments (CAA). An earlier paper (XXXX et al. forthcoming) examined the CPA period in detail and found a significant improvement in performance across all types of authorities in all parts of the country during this period. The current paper is intended to complement this earlier analysis and provide a longer term perspective on the performance of the benefits service under successive regimes between 1993 and 2010. The findings show that under CCT the performance of the system was poor, there were wide variations in individual local authority’s performance, with many acknowledged inadequacies in the system and unacceptably high levels of fraud. However in this period and in the subsequent BV period the antecedents of some of the tools and techniques subsequently used to drive improvement in the CPA era were either put in place or were being developed

Comprehensive performance assessment and public services improvement in England? A case study of the benefits administration service in local government

The purpose of this paper is to independently evaluate the impact of the Comprehensive Performance Assessment regime on one particular public service, namely the provision of Council Tax and Housing Benefits distributed by local authorities throughout the course of the regime. This service was assessed in every iteration of the CPA methodologies and it included one of the few key performance indicators (KPIs) where the definition of the performance indicator, the means of collection and the public reporting of its results, remained the same throughout the CPA period between 2002 and 2008

Improvements in Cd stable isotope analysis achieved through use of liquid–liquid extraction to remove organic residues from Cd separates obtained by extraction chromatography

Organic compounds released from resins that are commonly employed for trace element separations are known to have a detrimental impact on the quality of isotopic analyses by MC-ICP-MS. A recent study highlighted that such effects can be particularly problematic for Cd stable isotope measurements (M. Gault-Ringold and C. H. Stirling, J. Anal. At. Spectrom., 2012, 27, 449–459). In this case, the final stage of sample purification commonly applies extraction chromatography with Eichrom TRU resin, which employs particles coated with octylphenyl-N,N-di-isobutyl carbamoylphosphine oxide (CMPO) dissolved in tri-n-butyl phosphate (TBP). During chromatography, it appears that some of these compounds are eluted alongside Cd and cannot be removed by evaporation due to their high boiling points. When aliquots of the zero-ε reference material were processed through the purification procedure, refluxed in concentrated HNO(3) and analyzed at minimum dilution (in 1 ml 0.1 M HNO(3)), they yielded Cd isotopic compositions (ε(114/110)Cd = 4.6 ± 3.4, 2SD, n = 4) that differed significantly from the expected value, despite the use of a double spike technique to correct for instrumental mass fractionation. This result was accompanied by a 35% reduction in instrumental sensitivity for Cd. With increasing dilution of the organic resin residue, both of these effects are reduced and they are insignificant when the eluted Cd is dissolved in ≥3 ml 0.1 M HNO(3). Our results, furthermore, indicate that the isotopic artefacts are most likely related to anomalous mass bias behavior. Previous studies have shown that perchloric acid can be effective at avoiding such effects (Gault-Ringold and Stirling, 2012; K. C. Crocket, M. Lambelet, T. van de Flierdt, M. Rehkämper and L. F. Robinson, Chem. Geol., 2014, 374–375, 128–140), presumably by oxidizing the resin-derived organics, but there are numerous disadvantages to its use. Here we show that liquid–liquid extraction with n-heptane removes the organic compounds, dramatically improving quality of the Cd isotope data for samples that are analyzed at or close to minimum dilution factors. This technique is quick, simple and may be of use prior to analysis of other isotope systems where similar resins are employed

Modelling the response of vascular tumours to chemotherapy: A multiscale approach

An existing multiscale model is extended to study the response of a vascularised tumour to treatment with chemotherapeutic drugs which target proliferating cells. The underlying hybrid cellular automaton model couples tissue-level processes (e.g. blood flow, vascular adaptation, oxygen and drug transport) with cellular and subcellular phenomena (e.g. competition for space, progress through the cell cycle, natural cell death and drug-induced cell kill and the expression of angiogenic factors). New simulations suggest that, in the absence of therapy, vascular adaptation induced by angiogenic factors can stimulate spatio-temporal oscillations in the tumour's composition.\ud \ud Numerical simulations are presented and show that, depending on the choice of model parameters, when a drug which kills proliferating cells is continuously infused through the vasculature, three cases may arise: the tumour is eliminated by the drug; the tumour continues to expand into the normal tissue; or, the tumour undergoes spatio-temporal oscillations, with regions of high vascular and tumour cell density alternating with regions of low vascular and tumour cell density. The implications of these results and possible directions for future research are also discussed

An Experimental Analysis of Compliance in Dynamic Emissions Markets

Two important design elements for emission trading programs are whether and to what extent firms are able to bank emissions permits, and how these programs are to be enforced. In this paper we present results from laboratory emissions markets designed to investigate enforcement and compliance when these markets allow permit banking. Banking is motivated by a decrease in the aggregate permit supply in the middle of multi-period trading sessions. Consistent with theoretical insights, our experiments suggest that high permit violation penalties have little deterrence value in dynamic emissions markets, and that the main challenge of enforcing these programs is to motivate truthful self-reports of emissions.compliance, enforcement, emissions trading, laboratory experiments, permit markets, permit banking

Imperfect Enforcement of Emissions Trading and Industry Welfare: A Laboratory Investigation

This paper uses laboratory experiments to investigate the performance of emission permit markets when compliance is imperfectly enforced. In particular we examine deviations in observed aggregate payoffs and expected penalties from those derived from a model of risk-neutral payoff-maximizing firms. We find that the experimental emissions markets were reasonably efficient at allocating individual emission control choices despite imperfect enforcement and significant noncompliance. However, violations and expected penalties were lower than predicted when these are predicted to be high, but were about the same as predicted values when these values were predicted to be low. Thus, although a standard model of compliance with emissions trading programs tends to predict significantly higher violations than we observe when subjects have strong incentives to violate their emissions permits, individual emissions control responsibilities are distributed among firms as predicted.enforcement, compliance, emissions trading, permit markets, pollution, laboratory experiments