Can coercive formulations lead to fast and accurate solution of the Helmholtz equation?

A new, coercive formulation of the Helmholtz equation was introduced in [Moiola, Spence, SIAM Rev. 2014]. In this paper we investigate $h$-version Galerkin discretisations of this formulation, and the iterative solution of the resulting linear systems. We find that the coercive formulation behaves similarly to the standard formulation in terms of the pollution effect (i.e. to maintain accuracy as $k\to\infty$, $h$ must decrease with $k$ at the same rate as for the standard formulation). We prove $k$-explicit bounds on the number of GMRES iterations required to solve the linear system of the new formulation when it is preconditioned with a prescribed symmetric positive-definite matrix. Even though the number of iterations grows with $k$, these are the first such rigorous bounds on the number of GMRES iterations for a preconditioned formulation of the Helmholtz equation, where the preconditioner is a symmetric positive-definite matrix.Comment: 27 pages, 7 figure

Rural Homeownership and Labor Mobility in the U.S.

Labor and Human Capital,

The impact of study support : a report of a longitudinal study into the impact of participation in out-of-school-hours learning on the academic attainment, attitudes and school attendance of secondary school students

Study support makes a difference. It has an impact on three key aspects of students’ school careers: • attainment at GCSE and KS3 SATs; • attitudes to school; • attendance at school. These findings were consistent for all groups of students in all schools in the study. - Study support can help to improve schools and can influence the attitudes to learning of teachers and parents as well as students

Foreign Direct Investment in Manufacturing Sector in Malaysia

This paper analyses the determinants of foreign direct investment (FDI) in the manufacturing sector in Malaysia from eleven countries during the period 1988 to 2000. The empirical results indicate that gross domestic product, lending interest rate, labour productivity, exports to home country and imports from home country significantly influenced the level of FDI inflows into Malaysia. However, exchange rate, exchange rate variation, wage and openness index were not important in influencing FDI.foreign direct investment, manufacturing sector, International Relations/Trade,

Adapting a Remote Laboratory Architecture to Support Collaboration and Supervision

Interest in, and use of, remote laboratories has been rapidly growing. These laboratories provide remote access, via the internet, to real laboratory equipment. Under appropriate circumstances they can support or even replace traditional (proximal) laboratories, provide improved access at reduced cost, and encourage inter-institutional sharing of expensive resources. Most attention to date has been on the development of the core infrastructure that manages access and interaction, and to a lesser extent consideration of pedagogic issues such as which learning outcomes are best suited to this modality. There has however been a recent recognition of the importance of also considering how collaboration and supervision can also be supported. In this paper we discuss a novel approach to the integration of support for multi-user distributed access to a single laboratory instance. The approach retains the benefits of the lightweight client inherent in the underlying architecture

The impact of herbicide tolerant oilseed rape in selected agro-ecosystems

A range of field studies of cross pollination between herbicide tolerant and conventional oilseed rape crops and plots were conducted to demonstrate the effects of variety, distance, pollen source and sink size and intervening crop on levels of outcrossing. Experiments investigating the influence of variety on outcrossing showed that hybrid oilseed rape varieties containing high proportions of male sterile plants (varietal associations) were pollinated at higher frequencies than standard fully fertile varieties. Studies conducted using various sizes of genetically modified herbicide tolerant (GMHT) pollen sources showed that small GMHT feral populations cross pollinated with crops in close proximity and the levels of contamination obtained depended on the genotype of the conventional crop. Long range cross pollination of male sterile oilseed rape receptor plots showed that pollination events were measurable at up to 600m from the large GMHT pollen source. Results from a study of cross pollination between mixed populations of GMHT oilseed rape plants and conventional varieties also demonstrated that a hybrid rape type (varietal association) was cross pollinated at considerably higher levels than an open pollinated and a fully restored hybrid variety. Evidence gathered in the experiment suggested that, over a wide range of initial GMHT contamination rates, the final proportion of GMHT seed in the total population was a constant fraction of the initial contamination rate. Outcrossing data was used to compare negative exponential and inverse power law models for their fit to describe the observed relationship between cross pollination and distance from source. Results showed that the inverse power law provided a better fit of the data. This demonstrated that dispersal described by the inverse power law was more likely to lead to cross pollination at both near and large distances from the pollen source compared to the negative exponential model. The consequences of the likely ecological behaviour of GMHT traits resulting from the dispersal curves for regulation and risk assessment are discussed. The effect of the herbicides used in herbicide tolerant and conventional oilseed rape on weed populations were compared in a single season. Results suggested that the herbicides have different activity spectra thus resulting in a variety of surviving weed species in HT treatments. The change in active ingredient and the timing of herbicide application in HT winter oilseed rape crops will likely cause a change in the weed species that are being controlled or those that escape treatment. Levels of weed biomass recorded prior to harvest of the oilseed rape crop showed that there may be differences between treatments in terms of the quantity of seed returned to the seedbank from the range of weed species present. Limited data on the behaviour of herbicide tolerant volunteers showed that single and putative double-tolerant plants were as susceptible as conventional oilseed rape volunteers to normal selective herbicides used in cereal crops. Data from a number of elements of the studies on GM contamination rates, weed control, and seed bank estimates were used to develop a simple population projection model. The model used a Markov process to examine the fate of volunteer and feral populations of oilseed rape comprising a mixture of conventional and herbicide tolerant types. Results from the model indicated that the prevalence of the GMHT trait in the weed or feral population was more sensitive to the efficacy of control practices used in the rotation than the levels of cross-pollination and competition between the herbicide tolerant and conventional varieties in the mixed population. Thus, although the cross-pollination studies suggested that varietal associations are more likely to be cross-pollinated by GM pollen than fully fertile varieties, the projection model suggested that resulting differences in the prevalence of the GM trait in volunteer and feral populations may not be very large. Population projections from the model are compared with results from other modelling studies which have used more complex simulation approaches

Passive, broadband and low-frequency suppression of laser amplitude noise to the shot-noise limit using hollow-core fibre

We use hollow-core fibre to preserve the spectrum and temporal profile of picosecond laser pulses in CBD to suppress 2.6 dB of amplitude noise at MHz noise frequencies, to within 0.01 dB of the shot-noise limit. We provide an enhanced version of the CBD scheme that concatenates circuits to suppress over multiple frequencies and over broad frequency ranges --- we perform a first demonstration that reduces total excess amplitude noise, between 2 - 6 MHz, by 85%. These demonstrations enable passive, broad-band, all-guided fibre laser technology operating at the shot-noise limit.Comment: 8 pages, 8 figure

"Responsible drinkers create all the atmosphere of a mortuary" : policy implementation of responsible drinking in Scotland

The purpose of this paper is to explore the reaction of customer facing staff and their attitude to the introduction of high profile corporate social responsibility (CSR) programmes; in particular their level of awareness and willingness to implement them. Conducted using a series of site visits and interviews with managers working within the licensed trade, this was followed up with structured interviews of "front line" staff. Despite high levels of awareness of both the social problems relating to alcohol consumption and the legislative changes, engagement with operational CSR was limited and often disinterested. Legal and societal expectations regarding drunkenness are of little concern. This paper is concerned with nascent legislation, the full impact and success of which has not yet emerged. Reviewing this study in five years would add to the strength of the results. Limited to Scotland due to its devolved licensing laws, however, it clearly highlights lack of employee engagement with CSR. Despite placing CSR issues at the forefront of day to day operations within the licensed trade there is little empirical evidence around customer facing staff engagement. CSR is a dynamic process that relies on the involvement of employees for its successful implementation. A new CSR implementation matrix is presented which allows hospitality businesses to be positioned according to levels of both management and employee engagement with CSR policies