Supporting public availability and accessibility with Elvin: experiences and reflections.

We provide a retrospective account of how a generic event notification service called Elvin and a suite of simple client applications: CoffeeBiff, Tickertape and Tickerchat, came to be used within our organisation to support awareness and interaction. After overviewing Elvin and its clients, we outline various experiences from data collated across two studies where Elvin and its clients have been used to augment the workaday world to support interaction, to make digital actions visible, to make physical actions available beyond the location of action, and to support content and socially based information filtering. We suggest there are both functional and technical reasons for why Elvin works for enabling awareness and interaction. Functionally, it provides a way to produce, gather and redistribute information from everyday activities (via Elvin) and to give that information a perceptible form (via the various clients) that can be publicly available and accessible as a resource for awareness. The integration of lightweight chat facilities with these information sources enables awareness to easily flow into interaction, starting to re-connect bodies to actions, and starting to approximate the easy flow of interaction that happens when we are co-located. Technically, the conceptual simplicity of the Elvin notification, the wide availability of its APIs, and the generic functionality of its clients, especially Tickertape, have made the use of the service appealing to developers and users for a wide range of uses

GAEA Action Equations Paradigm

This technical report consists of two papers describing the GAEA action equations paradigm. Incremental Dynamic Semantics for Language-based Programming Environments explains why attribute grammars are not suitable for expressing dynamic semantics and presents action equations, an extension of attribute grammars suitable for specifying the static and the dynamic semantics of programming languages. It describes how action equations can be used to generate language-based programming environments that incrementally derive static and dynamic properties as the user modifies and debugs the program. Rapid Prototyping of Concurrent Programming Languages extends this technology to a concurrent framework. It describes an (unimplemented) system that generates a parallel interpreter for the language and provides runtime support for the synchronization primitives and other facilities in the language

Generation of Distributed Programming Environments

This technical report consists of three related papers in the area of distributed programming environments. Incremental Attribute Evaluation in Distributed Language-Based Environments presents algorithms that extend existing technology for the generation of single-user language-based editors from attribute grammars to the cases of multiple-user concurrent and distributed environments. Multi-User Distributed Language-Based Environment, an extended abstract, provides additional information on how to apply the algorithms. Reliability in Distributed Programming Environments presents additional algorithms that extend our results to unreliable networks

Lattice Supersymmetry and Topological Field Theory

It is known that certain theories with extended supersymmetry can be discretized in such a way as to preserve an exact fermionic symmetry. In the simplest model of this kind, we show that this residual supersymmetric invariance is actually a BRST symmetry associated with gauge fixing an underlying local shift symmetry. Furthermore, the starting lattice action is then seen to be entirely a gauge fixing term. The corresponding continuum theory is known to be a topological field theory. We look, in detail, at one example - supersymmetric quantum mechanics which possesses two such BRST symmetries. In this case, we show that the lattice theory can be obtained by blocking out of the continuum in a carefully chosen background metric. Such a procedure will not change the Ward identities corresponding to the BRST symmetries since they correspond to topological observables. Thus, at the quantum level, the continuum BRST symmetry is preserved in the lattice theory. Similar conclusions are reached for the two-dimensional complex Wess-Zumino model and imply that all the supersymmetric Ward identities are satisfied {\it exactly} on the lattice. Numerical results supporting these conclusions are presented.Comment: 18 pages, 2 figure

Evolution of the most recent common ancestor of a population with no selection

We consider the evolution of a population of fixed size with no selection. The number of generations $G$ to reach the first common ancestor evolves in time. This evolution can be described by a simple Markov process which allows one to calculate several characteristics of the time dependence of $G$. We also study how $G$ is correlated to the genetic diversity.Comment: 21 pages, 10 figures, uses RevTex4 and feynmf.sty Corrections : introduction and conclusion rewritten, references adde

The World According To GARP

This technical report consists of two papers describing the GARP concurrent programming system. Garp: Graph Abstractions for Concurrent Programming investigates construction of dynamic process topologies in parallel processing languages. It proposes the use of a graph-grammar based formalism to control the complexities arising from trying to program such dynamic networks. Garp: A Graphical Language for Concurrent Programming describes the GARP system, a programming environment that implements this graph-grammar approach, and gives solutions to example problems in which the topologies of concurrent systems dynamically change

MERCURY: Distributed Incremental Attribute Grammar Evaluation

This technical report consists of the two most recent papers from the MERCURY project Multiuser, Distributed Language-Based Environments explains the application of incremental attribute grammar evaluation algorithms to generation of distributed programming environments and describes the implementation of the MERCURY system. Version and Configuration Control in Distributed Language-Based Environments presents new algorithms that permit MERCURY to support multiple versions and configurations of modules and to more efficiently propagate changes to aggregate attributes

A Perturbative Calculation of the Electromagnetic Form Factors of the Deuteron

Making use of the effective field theory expansion recently developed by the authors, we compute the electromagnetic form factors of the deuteron analytically to next-to-leading order (NLO). The computation is rather simple, and involves calculating several Feynman diagrams, using dimensional regularization. The results agree well with data and indicate that the expansion is converging. They do not suffer from any ambiguities arising from off-shell versus on-shell amplitudes.Comment: 22 pages, 8 figures. Discussion of effective range theory added, typos correcte

Accounts from developers of generic health state utility instruments explain why they produce different QALYs: a qualitative study

Purpose and setting: Despite the label generic health state utility instruments (HSUIs), empirical evidence shows that different HSUIs generate different estimates of Health-Related Quality of Life (HRQoL) in the same person. Once a HSUI is used to generate a QALY, the difference between HSUIs is often ignored, and decision-makers act as if \u27a QALY is a QALY is a QALY\u27. Complementing evidence that different generic HSUIs produce different empirical values, this study addresses an important gap by exploring how HSUIs differ, and processes that produced this difference. 15 developers of six generic HSUIs used for estimating the QOL component of QALYs: Quality of Well-Being (QWB) scale; 15 Dimension instrument (15D); Health Utilities Index (HUI); EuroQol EQ-5D; Short Form-6 Dimension (SF-6D), and the Assessment of Quality of Life (AQoL) were interviewed in 2012-2013. Principal findings: We identified key factors involved in shaping each instrument, and the rationale for similarities and differences across measures. While HSUIs have a common purpose, they are distinctly discrete constructs. Developers recalled complex developmental processes, grounded in unique histories, and these backgrounds help to explain different pathways taken at key decision points during the HSUI development. The basis for the HSUIs was commonly not equivalent conceptually: differently valued concepts and goals drove instrument design and development, according to each HSUI\u27s defined purpose. Developers drew from different sources of knowledge to develop their measure depending on their conceptualisation of HRQoL. Major conclusions/contribution to knowledge: We generated and analysed first-hand accounts of the development of the HSUIs to provide insight, beyond face value, about how and why such instruments differ. Findings enhance our understanding of why the six instruments developed the way they did, from the perspective of key developers of those instruments. Importantly, we provide additional, original explanation for why a QALY is not a QALY is not a QALY