On the boundary Ising model with disorder operators

We extend the well-known method of calculating bulk correlation functions of the conformal Ising model via bosonisation to situations with boundaries. Oshikawa and Affleck have found the boundary states of two decoupled Ising models in terms of the orbifold of a single free boson compactified on a circle of radius r=1; we adapt their results to include disorder operators. Using these boundary states we calculate the expectation value of a single disorder field on a cylinder with free boundary conditions and show that in the appropriate limits we recover the standard and frustrated partition functions. We also show how to calculate Ising correlation functions on the upper half plane.Comment: 12 pages, Latex2e, 6 figure

Defects in the Tri-critical Ising model

We consider two different conformal field theories with central charge c=7/10. One is the diagonal invariant minimal model in which all fields have integer spins; the other is the local fermionic theory with superconformal symmetry in which fields can have half-integer spin. We construct new conformal (but not topological or factorised) defects in the minimal model. We do this by first constructing defects in the fermionic model as boundary conditions in a fermionic theory of central charge c=7/5, using the folding trick as first proposed by Gang and Yamaguchi. We then acting on these with interface defects to find the new conformal defects. As part of the construction, we find the topological defects in the fermionic theory and the interfaces between the fermionic theory and the minimal model. We also consider the simpler case of defects in the theory of a single free fermion and interface defects between the Ising model and a single fermion as a prelude to calculations in the tri-critical Ising model.Comment: 54 pages, 5 figures, version as accepted for publication with minor change

A non-rational CFT with c=1 as a limit of minimal models

We investigate the limit of minimal model conformal field theories where the central charge approaches one. We conjecture that this limit is described by a non-rational CFT of central charge one. The limiting theory is different from the free boson but bears some resemblance to Liouville theory. Explicit expressions for the three point functions of bulk fields are presented, as well as a set of conformal boundary states. We provide analytic and numerical arguments in support of the claim that this data forms a consistent CFT.Comment: latex2e, 37 pages, 4 figure

Exploiting the Design Freedom of RM

This paper details how Rapid Manufacturing (RM) can overcome the restrictions imposed by the inherent process limitations of conventional manufacturing techniques and become the enabling technology in fabricating optimal products. A new design methodology capable of exploiting RM’s increased design freedom is therefore needed. Inspired by natural world structures of trees and bones, a multi-objective, genetic algorithm based topology optimisation approach is presented. This combines multiple unit cell structures and varying volume fractions to create a heterogeneous part structure which exhibits a uniform stress distribution.Mechanical Engineerin

The Somme - innocence lost

Lecture showing the effect of the Battle of the Somme with the focus on the Kent infantry regiment

The reflection coefficient for minimal model conformal defects from perturbation theory

We consider a class of conformal defects in Virasoro minimal models that have been defined as fixed points of the renormalisation group and calculate the leading contribution to the reflection coefficient for these defects. This requires several structure constants of the operator algebra of the defect fields, for which we present a derivation in detail. We compare our results with our recent work on conformal defects in the tricritical Ising model.Comment: 22 pages; v2: minor changes, defect field transformation law clarified, reference adde

Maidstone and the First World War: friendly alien recruitment and the military service convention

Maidstone was used as a training depot for thousands of volunteers and conscripts in the First World War, and was selected as a base for those recruits of Friendly Alien status. Their treatment by the Army and the reception they received from the local population are examined in this article

Numerical simulation of neutron radiation effects in avalanche photodiodes

A new one-dimensional (1-D) device model developed for the simulation of neutron radiation effects in silicon avalanche photodiodes is described. The model uses a finite difference technique to solve the time-independent semiconductor equations across a user specified structure. The model includes impact ionization and illumination allowing accurate simulation with minimal assumptions. The effect of neutron radiation damage is incorporated via the introduction of deep acceptor levels subject to Shockley-Read-Hall statistics. Preliminary analysis of an EG&G reverse APD structure is compared with experimental data from a commercial EG&G C30719F APD

Operation Market Garden - strategic masterstroke or battle of the egos?

In September 1944, the allies undertook the largest ever airborne operation, apparently in an effort to capitalise on the German withdrawal from France and Belgium and end the war in the west by encircling the Ruhr. But what really lay behind this most audacious and daring attempt to finish the war in 1944? Inter allied rivalry, at the highest levels of military command, and the pursuit of personal ambition, will be discussed to reveal some of the reasons for failure and the post war bitterness it engendered