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

Electronic structure of superconducting graphite intercalate compounds: The role of the interlayer state

Although not an intrinsic superconductor, it has been long--known that, when intercalated with certain dopants, graphite is capable of exhibiting superconductivity. Of the family of graphite--based materials which are known to superconduct, perhaps the most well--studied are the alkali metal--graphite intercalation compounds (GIC) and, of these, the most easily fabricated is the C${}_8$K system which exhibits a transition temperature $\bm{T_c\simeq 0.14}$K. By increasing the alkali metal concentration (through high pressure fabrication techniques), the transition temperature has been shown to increase to as much as $\bm 5$K in C${}_2$Na. Lately, in an important recent development, Weller \emph{et al.} have shown that, at ambient conditions, the intercalated compounds \cyb and \cca exhibit superconductivity with transition temperatures $\bm{T_c\simeq 6.5}$K and $\bm{11.5}$K respectively, in excess of that presently reported for other graphite--based compounds. We explore the architecture of the states near the Fermi level and identify characteristics of the electronic band structure generic to GICs. As expected, we find that charge transfer from the intercalant atoms to the graphene sheets results in the occupation of the $\bm\pi$--bands. Yet, remarkably, in all those -- and only those -- compounds that superconduct, we find that an interlayer state, which is well separated from the carbon sheets, also becomes occupied. We show that the energy of the interlayer band is controlled by a combination of its occupancy and the separation between the carbon layers.Comment: 4 Figures. Please see accompanying experimental manuscript "Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca" by Weller et a

Supporting Disconnectedness – Transparent Information Delivery for Mobile and Invisible Computing

As computing devices become ubiquitous and increasingly mobile, it is becoming apparent that the directed peerto-peer communication model has shortcomings for many forms of distributed interprocess communication. Undirected communication, including content-based messaging, is becoming increasingly common. This paper examines the issues involved in supporting content-based messaging to both mobile devices and users using a combination of connected and mobile (possibly disconnected) devices. These issues include persistence, multi-client shared subscriptions, non-destructive notification receipt, and notification expiry. The discussion is placed in the context of the development of a proxy-server to provide disconnectedness suppor

Tickertape: Notification and Communication in a Single Line

This paper outlines an awareness application called Tickertape. Tickertape is a tool that displays event notifications in the form of scrolling messages across a single-line window. The Tickertape message window provides an interface to a world of highly tailorable transient information. We provide an overview of Tickertape features and then discuss its specific use within a semi-commercial research organisation. We note that although Tickertape's evolution was incidental rather than purposeful, it is being extensively used within our organisation. Usage data and interviews suggest that there is a select core group of users who use Tickertape for both work and leisure. Other more casual users use the tool sporadically for leisure purposes only. We highlight our current goal which is to optimise Tickertape usage within the work environment. We hope to achieve this by enhancing the Tickertape user interface and encouraging its widespread use within the organisation. Our long-term vision ..