Source Galerkin Calculations in Scalar Field Theory

In this paper, we extend previous work on scalar $\phi^4$ theory using the Source Galerkin method. This approach is based on finding solutions $Z[J]$ to the lattice functional equations for field theories in the presence of an external source $J$. Using polynomial expansions for the generating functional $Z$, we calculate propagators and mass-gaps for a number of systems. These calculations are straightforward to perform and are executed rapidly compared to Monte Carlo. The bulk of the computation involves a single matrix inversion. The use of polynomial expansions illustrates in a clear and simple way the ideas of the Source Galerkin method. But at the same time, this choice has serious limitations. Even after exploiting symmetries, the size of calculations become prohibitive except for small systems. The calculations in this paper were made on a workstation of modest power using a fourth order polynomial expansion for lattices of size $8^2$,$4^3$,$2^4$ in $2D$, $3D$, and $4D$. In addition, we present an alternative to the Galerkin procedure that results in sparse matrices to invert.Comment: 31 pages, latex, figures separat

New Numerical Method for Fermion Field Theory

A new deterministic, numerical method to solve fermion field theories is presented. This approach is based on finding solutions $Z[J]$ to the lattice functional equations for field theories in the presence of an external source $J$. Using Grassmann polynomial expansions for the generating functional $Z$, we calculate propagators for systems of interacting fermions. These calculations are straightforward to perform and are executed rapidly compared to Monte Carlo. The bulk of the computation involves a single matrix inversion. Because it is not based on a statistical technique, it does not have many of the difficulties often encountered when simulating fermions. Since no determinant is ever calculated, solutions to problems with dynamical fermions are handled more easily. This approach is very flexible, and can be taylored to specific problems based on convenience and computational constraints. We present simple examples to illustrate the method; more general schemes are desirable for more complicated systems.Comment: 24 pages, latex, figures separat

Ways of seeing evaluation

Copyright @ 2011 Brunel UniversityThis report summarises the evaluation of Ways of Seeing, a community arts project funded by the Heritage Lottery Fund and hosted by the Lightbox, Woking, Surrey from 2008-11. The people involved have had remarkable experiences, choosing how to take part in each stage of preparations for a major public art exhibition. All those involved had disabilities, primarily arising from mental health issues but also including physical disabilities. The project was skilfully designed and led to enable them to make a significant contribution, enhancing their well-being and resulting in the Ways of Seeing exhibition which was widely appreciated. The Lightbox is an award-winning museum, housing a permanent local history exhibition as well as touring major art exhibitions. The Ingram Modern Art collection is on permanent loan, with regular exhibitions of work from the collection. Since the Lightbox opened in 2007, it has had a stated intention to promote local community involvement, successfully obtaining external funding to support this work. Ways of Seeing was the most ambitious project to date, aiming to exhibit selected work from the Ingram Collection alongside art created as part of the project by local disabled people. The emphasis on ways of seeing reflected an interest in their diverse perspectives, especially in relation to long term mental health problems. A steering group was set up, with members from local mental health initiatives and an evaluation team from Brunel University. The project started by orientating participants to how art is created and exhibited, with a series of visits and workshops on major art collections and artists’ studios. This stage successfully attracted a range of people and was followed by taster workshops of different art techniques. Then participants examined every item in the Ingram Collection and agreed a selection to inspire their own artistic responses. All-day workshops were convened, covering the same techniques as before and giving everyone space and time to get started. Curation of the exhibition gathered pace as final selections were made from participants’ art works and the Ingram Collection. The exhibition offered opportunities for everyone to have selections of their work exhibited to the public alongside the selected work from the Ingram Collection. A video artist captured the project in film and an MSc occupational therapy student from Brunel University undertook independent interviews of participants. It is clear that this multi-stage and carefully considered approach was highly successful in engaging people who are often excluded from arts events and venues. It was also successful in engaging the public in an innovative and thought-provoking exhibition, challenging assumptions about mental health and promoting the benefits of participation. The willingness of the Lightbox to host and support the project was essential. Based on tolerance, respect and a sympathetic curiosity, with clear and skilled leadership, the project enabled participants to make significant changes in their own lives.This study was funded by the Heritage Lottery Fund

A Checklist of Megaloptera and Neuroptera (Planipennia) of Indiana

Sixty-five species of the insect orders Megaloptera and Neuroptera have been confirmed as being distributed in the state of Indiana, with the majority representing new state records

Molecular Simulations of Ultrafast Radiation Induced Melting at Metal-Semiconductor Interfaces

Understanding radiation induced ultrafast melting at material interfaces is essential in designing robust electronic devices for aviation/space applications and in laser machining. While it is difficult to achieve the spatial and temporal resolution required to quantify the phenomenon experimentally, simulations can provide the detailed mechanisms of the structural changes that happen during phase transition. In this work, we use molecular simulations to study the effect of radiation damage on silicon carbide (SiC) - tungsten (W) interfaces which is of interest in high power electronics. A multi-scale approach is involved wherein the reactions at the interfaces are quantified using ab-initio molecular dynamics (MD) simulations and classical MD simulations are employed to understand the structural and diffusional changes across the material interface. Finally, coarse-grained Lennard-Jones type models are used to study the larger scale mechanisms and structures obtained due to the induced damages. We show that the response of the material to radiation damage depends on factors such as energy of the incident radiation, thermal properties, and molecular structure of the material

The weld-brazing metal joining process

Superior mechanical properties were obtained in metal joints weld-brazed between faying surfaces. Weld-braze applications and advantages are listed