"Sub-Hertz" Dielectric Spectroscopy

Dielectric spectroscopy measurements below 1 Hz are often dominated by “conduction-like” effects. For this reason, they often appear to be dismissed as being of little interest. In this paper two “sub-hertz” responses are considered that give insights into the insulating sys-tems concerned. The first system is that of cross-linked polyethylene, taken from a power cable system. Measurements at temperatures between 60°C and close to melting at 100°C show a change in characteristic from a percolation process to a “true” DC conduction at close to the melting point. Using DC conductivities, it appears to be possible to show whether the cable has been subjected to thermo-electric ageing. This might give insights into where the conduction and hence the ageing in the XLPE is occurring. The second system is an epoxy composite. By considering the sub-hertz response, it is possible to demonstrate the effect of the interface between the filler and the epoxy matrix. In this system, ageing, resulting in delamination between the glass fiber filler and the epoxy, is clearly detected by sub-hertz dielectric spectroscopy. This process is likely to be facilitated by the presence of water, which is known to lead to mechanical failure in such systems, and which can also be detected by "sub-hertz" dielectric spectroscopy. The implications for nano-dielectrics are then briefly considered

Perturbation Theory for Antisymmetric Tensor Fields in Four Dimensions

Perturbation theory for a class of topological field theories containing antisymmetric tensor fields is considered. These models are characterized by a supersymmetric structure which allows to establish their perturbative finiteness.Comment: 23 page

A general formula of the effective potential in 5D SU(N) gauge theory on orbifold

We show a general formula of the one loop effective potential of the 5D SU(N) gauge theory compactified on an orbifold, $S^1/Z_2$. The formula shows the case when there are fundamental, (anti-)symmetric tensor and adjoint representational bulk fields. Our calculation method is also applicable when there are bulk fields belonging to higher dimensional representations. The supersymmetric version of the effective potential with Scherk-Schwarz breaking can be obtained straightforwardly. We also show some examples of effective potentials in SU(3), SU(5) and SU(6) models with various boundary conditions, which are reproduced by our general formula.Comment: 22 pages;minor corrections;references added;typos correcte

Some Aspects of Classical and Quantum Phases

We study classical and quantum phases in the adiabatic Born-Oppenheimer context. These include a classical astronomical case, the general dual description of the phases, a new "Paradox" connected to scattering Berry phase and its resolution and various elaboration of topological/geometrical/non-abelian phases.Comment: 18 pages, 4 figure

Network synchronization: Optimal and Pessimal Scale-Free Topologies

By employing a recently introduced optimization algorithm we explicitely design optimally synchronizable (unweighted) networks for any given scale-free degree distribution. We explore how the optimization process affects degree-degree correlations and observe a generic tendency towards disassortativity. Still, we show that there is not a one-to-one correspondence between synchronizability and disassortativity. On the other hand, we study the nature of optimally un-synchronizable networks, that is, networks whose topology minimizes the range of stability of the synchronous state. The resulting ``pessimal networks'' turn out to have a highly assortative string-like structure. We also derive a rigorous lower bound for the Laplacian eigenvalue ratio controlling synchronizability, which helps understanding the impact of degree correlations on network synchronizability.Comment: 11 pages, 4 figs, submitted to J. Phys. A (proceedings of Complex Networks 2007

Possible Detection of Causality Violation in a Non-local Scalar Model

We consider the possibility that there may be causality violation detectable at higher energies. We take a scalar nonlocal theory containing a mass scale $\Lambda$ as a model example and make a preliminary study of how the causality violation can be observed. We show how to formulate an observable whose detection would signal causality violation. We study the range of energies (relative to $\Lambda$) and couplings to which the observable can be used.Comment: Latex, 30 page

Assessing the impact of Pupil Premium funding on primary school segregation and attainment

Using funding to improve educational outcomes is a common policy approach, usually assumed to be effective; but it is less commonly agreed how the money should be routed, and what it should be used for. This paper examines the possible impact of one approach wherein extra funding is provided by the state to schools, rather than teachers, families, or students. Pupil Premium funding has been provided to schools in England since 2011, to help overcome socio-economic segregation between schools, and reduce the attainment gap between disadvantaged pupils and their peers. Yet there is little international evidence that such a funding system can raise attainment directly. Some important stakeholders are now considering whether Pupil Premium should cease, be used for more general school financing, or have a new objective such as social mobility or hiring more teachers. It is therefore essential to know whether the policy has had a beneficial impact in the nine years since its inception. Evaluating the impact of such a funding policy is not easy because it is national and so there is no simple comparator group, and the relevant outcomes are also sensitive to demographic, economic and other concurrent policy changes. These issues are addressed using the National Pupil Database and Annual Schools Census, and by comparing the poverty gap in primary schools from 2006 to 2019, focusing on pupils who would have attracted Pupil Premium funding, if it existed, in any year and under any economic conditions. After 2010, the gap in segregation between these long-term disadvantaged pupils and their peers became substantially lower in Year 1 and Year 6, and their attainment improved relative to their peers at age 7. At age 11 there was also an improvement after 2010, but the assessment changed after 2014 and this complicated the pattern. A regression model also suggests that relative attainment for poor pupils improved markedly in the Pupil Premium era. Improvement was marked in regions like the North of England which have faced criticism for apparently “failing” their poor pupils. On this evidence, we argue for retaining the Pupil Premium policy

Best practice in conducting RCTs: Lessons learnt from an independent evaluation of the Response-to-Intervention programme

This paper presents the findings of the first independent UK evaluation of a large-scale randomised controlled trial of Response-to-Intervention, used as a catch-up literacy intervention. A total of 385 pupils in their final year of primary school (Year 6) were involved in the study (181 treatment and 204 control). These were identified as those at-risk of not achieving the threshold Level 4 in English at Key Stage 2. The pupils came from 49 schools across England. Twenty-seven schools were randomised to receive treatment immediately and 22 schools, which formed the control, were randomised to receive the intervention later. RTI was delivered in the summer term in preparation for pupil transfer to secondary school. The overall impact based on the standardised New Group Reading Test (NGRT) showed an ‘effect’ size of +0.19, and of +0.48 when considering only free school meal eligible pupils. However, these results must be viewed with considerable caution given the high attrition (over 25%) especially from the control group, and unclear identification of pupils eligible for the intervention. The fact that the evaluators did not have direct contact with schools when trying to identify eligible pupils, and that the developers wanted to use the pre-test to identify eligible pupils, led to this being a weak trial. The significance of the work therefore lies at least as much in the lessons learnt as in the headline figures. We learnt that ideally no more than two parties should be involved in communicating with schools, so that relevant instructions are passed quickly and acted upon promptly. This helps minimise the risk of misunderstanding and dropout post-allocation. Prior training on the technicalities of trials and research in general is necessary for both developers and any staff delivering the intervention so that all parties involved understand their commitment and the need to provide accurate and complete data. In future trials of RTI, it would be better for individual eligible pupils to be randomised rather than schools. RTI should ideally be given a whole year to allow the full cycle to be implemented, and it should be delivered daily for at least 30 minutes

The difficulties of judging what difference the Pupil Premium has made to school intakes and outcomes in England

Pupil Premium funding has been provided to schools in England since 2011, to help overcome socio-economic segregation between schools, and reduce the attainment gap between disadvantaged pupils and their peers – nationally, regionally, and within individual schools. Yet there is little international evidence that such a funding system can raise attainment directly. Some important stakeholders are now considering whether Pupil Premium should cease, be used for more general school financing, or have a new objective such as social mobility. It is therefore essential to know whether the policy has had a beneficial impact in the eight years since its inception. Previous estimates suggest that segregation and the raw attainment gap have been reducing erratically and slowly since 2011, but that this is generally part of a longer-term historical trend and cannot simply be attributed to the Pupil Premium policy. However, evaluating the impact of such a funding policy is not that simple. It is fraught with difficulties because of changes over time in the economy, legal definitions of indicators of disadvantage, the prevalence of disadvantage, the metrics used, and in the ways attainment has been summarised. Previous research has generally not taken these into account and also largely ignores the length and depth of disadvantage, and the difference this makes to patterns of attainment. Hence, previous estimates of the attainment gap are probably insecure. To illustrate the problems arising in judging changes over time and between areas and schools in segregation and the attainment gap, data from the National Pupil Database and School-level Annual Schools Census are correlated, cross-plotted, and modelled using regression, and time series analyses. This paper introduces a new analysis that considers changes in the prevalence of FSM-eligibility, private school attendance, GDP and the duration of individual poverty. It illustrates the importance of these factors in an analysis of the attainment gap in each local authority in England. Net of such factors, the results show that segregation has declined unexpectedly since 2011, suggesting that Pupil Premium may be working. The Pupil Premium policy should remain until further research is complete, and in the meantime claims of the relative success and failure of schools and regions should take into account the cautions noted in this paper