Production of pace as collaborative activity

In this paper we investigate the concept of pace development and management among groups of people. We explore and compare groups visiting museums, and groups virtually co-located in a mixed reality system for a museum. In considering pace, and how to design to support it, we have to consider more than the speed or location of information display. We have to also take into consideration the social formation of pace through features such as the visitors' awareness of each other's location and attention. By considering aspects of collaboratively produced pace such as presenting engagement and disengagement, we offer suggestions as to how social handling of pace might be better supported by technology

Seamful interweaving: heterogeneity in the theory and design of interactive systems

Design experience and theoretical discussion suggest that a narrow design focus on one tool or medium as primary may clash with the way that everyday activity involves the interweaving and combination of many heterogeneous media. Interaction may become seamless and unproblematic, even if the differences, boundaries and 'seams' in media are objectively perceivable. People accommodate and take advantage of seams and heterogeneity, in and through the process of interaction. We use an experiment with a mixed reality system to ground and detail our discussion of seamful design, which takes account of this process, and theory that reflects and informs such design. We critique the 'disappearance' mentioned by Weiser as a goal for ubicomp, and Dourish's 'embodied interaction' approach to HCI, suggesting that these design ideals may be unachievable or incomplete because they underemphasise the interdependence of 'invisible' non-rationalising interaction and focused rationalising interaction within ongoing activity

A hybrid layout algorithm for sub-quadratic multidimensional scaling

Many clustering and layout techniques have been used for structuring and visualising complex data. This paper is inspired by a number of such contemporary techniques and presents a novel hybrid approach based upon stochastic sampling, interpolation and spring models. We use Chalmers' 1996 O(N/sup 2/) spring model as a benchmark when evaluating our technique, comparing layout quality and run times using data sets of synthetic and real data. Our algorithm runs in O(N/spl radic/N) and executes significantly faster than Chalmers' 1996 algorithm, whilst producing superior layouts. In reducing complexity and run time, we allow the visualisation of data sets of previously infeasible size. Our results indicate that our method is a solid foundation for interactive and visual exploration of data

Coordinating views for data visualisation and algorithmic profiling

A number of researchers have designed visualisation systems that consist of multiple components, through which data and interaction commands flow. Such multistage (hybrid) models can be used to reduce algorithmic complexity, and to open up intermediate stages of algorithms for inspection and steering. In this paper, we present work on aiding the developer and the user of such algorithms through the application of interactive visualisation techniques. We present a set of tools designed to profile the performance of other visualisation components, and provide further functionality for the exploration of high dimensional data sets. Case studies are provided, illustrating the application of the profiling modules to a number of data sets. Through this work we are exploring ways in which techniques traditionally used to prepare for visualisation runs, and to retrospectively analyse them, can find new uses within the context of a multi-component visualisation system

On-board processing satellite network architecture and control study

The market for telecommunications services needs to be segmented into user classes having similar transmission requirements and hence similar network architectures. Use of the following transmission architecture was considered: satellite switched TDMA; TDMA up, TDM down; scanning (hopping) beam TDMA; FDMA up, TDM down; satellite switched MF/TDMA; and switching Hub earth stations with double hop transmission. A candidate network architecture will be selected that: comprises multiple access subnetworks optimized for each user; interconnects the subnetworks by means of a baseband processor; and optimizes the marriage of interconnection and access techniques. An overall network control architecture will be provided that will serve the needs of the baseband and satellite switched RF interconnected subnetworks. The results of the studies shall be used to identify elements of network architecture and control that require the greatest degree of technology development to realize an operational system. This will be specified in terms of: requirements of the enabling technology; difference from the current available technology; and estimate of the development requirements needed to achieve an operational system. The results obtained for each of these tasks are presented

EFFICIENT ANALYTIC COMPUTATION OF HIGHER-ORDER QCD AMPLITUDES

We review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. Particularly useful are the constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes. Certain sequences of one-loop helicity amplitudes with an arbitrary number of external gluons have been obtained using these constraints.Comment: Talk given at Beyond the Standard Model IV, December 13-18 1994, Lake Tahoe, CA. Latex, 4 pages, no figures