Showing papers by "Nigel Davies published in 1992"
TL;DR: It is confirmed that the alpha: beta share of parental effort in polyandry was determined by their share of matings, not by their dominance rank per se, and experimental manipulation of a monogamous male's mating access did not influence his parental effort, despite paternity loss.
208 citations
TL;DR: Research into handling multimedia in the Advanced Networked Systems Architecture (ANSA), a state of the art distributed platform, is described and it is shown that ANSA, although comprehensive in scope, fails to explicitly address multimedia requirements.
Abstract: Distributed systems has been an area of intense activity over the past ten years. The subject is entering a stage of maturity with work now focussing on standards for Open Distributed Processing (ODP). However, it is important that standardisation is responsive to new demands on the technology. This is especially true with the emergence of high speed networks in general and multimedia computing in particular. This paper describes research into handling multimedia in the Advanced Networked Systems Architecture (ANSA), a state of the art distributed platform. It is shown that ANSA, although comprehensive in scope, fails to explicitly address multimedia requirements. A number of specific extensions are proposed to remedy these omissions. These include streams, as an abstraction over multimedia protocols, and chains, as a generic control interface to multimedia devices (including storage servers). Importantly, the proposed extensions do not affect the core ANSA architecture, but instead add the necessary functionality in terms of additional services.
80 citations
TL;DR: The mate-guarding and copulation behaviour of monogamous and polyandrous dunnocks was investigated to determine how males ‘valued’ copulations achieved at various stages of the mating period, withCopulation rates increased with competition for matings, being highest in polyandry where two males gained equal mating access.
44 citations
TL;DR: It is concluded that polyandry does not arise because two males are necessary for successful defence of the territory against neighbours, and mate guarding by alpha and monogamous males is necessary for maintaining exclusive mating access to females.
34 citations
03 Jan 1992
TL;DR: The implementation and use of a platform designed to support distributed multimedia applications that provides a programming interface compatible with emerging ODP standards, and uses a transputer based workstation enhancement unit to provide the necessary performance is described.
Abstract: The implementation and use of a platform designed to support distributed multimedia applications is described. The platform provides a programming interface compatible with emerging ODP standards, and uses a transputer based workstation enhancement unit to provide the necessary performance. Implementing such a platform, where the dual concerns of open systems compatibility and performance needed to be addressed, poses a unique set of challenges. The design decisions taken in our implementation are evaluated, and our experiences of both implementing and using the platform are presented.
20 citations
24 Sep 1992
TL;DR: The authors describe an initial approach to providing such a platform, which attempted to factor out all real-time aspects of multimedia support onto a hardware based multimedia network interface unit, but lacks the flexibility and level of integration subsequently demanded by application programmers.
Abstract: Considerable progress has been made in the development of technologies to support distributed multimedia computing, but application platforms are needed to make such technology accessible to application programmers. The paper sets out requirements for such platforms and discusses the role of operating systems in object-oriented platform support. The authors describe an initial approach to providing such a platform which attempted to factor out all real-time aspects of multimedia support onto a hardware based multimedia network interface unit. This solution has been partially successful but lacks the flexibility and level of integration subsequently demanded by application programmers. Their response has been to re-design the multimedia network interface unit, placing more emphasis on the provision of dynamic services which require real-time operating system support. The new design described exploits and extends features of a distributed object-oriented micro-kernel to provide the necessary system wide support. >
6 citations
TL;DR: The Zenith research project is a research prototype of an object management system that is intended to meet the data-management requirements of the next generation of application domains, such as office information systems, integrated project support environments, and geographical information systems.
Abstract: The paper describes the Zenith research project, which is being carried out at the Universities of Kent and Lancaster, UK. It is a research prototype of an object management system that is intended to meet the data-management requirements of the next generation of application domains, such as office information systems, integrated project support environments, and geographical information systems. Zenith is designed to provide a flexible and adaptable platform for the management of distributed multimedia objects, on top of which specialized applications can easily be built. The design of the system reflects this goal. The object-management layer provides the high-level abstractions required for managing complex objects, and the base-services layer is responsible for the management of primitive entities stored on conventional and specialized devices, while maintaining appropriate location, media, and other transparencies. The earlier sections of the paper briefly discuss the background to the project, including the context of the Zenith environment and the philosophy that underlies its design. Subsequent sections concentrate on the object model and the object-oriented design of the prototype system architecture. Finally, the current status and implementation issues are presented, followed by some brief concluding remarks.
5 citations
01 Nov 1992
TL;DR: The requirements of distributed multimedia applications with respect to their support environments are discussed and a number of experimental systems are described which intend to provide the necessary facilities for multimedia applications.
Abstract: Considerable progress has been made in the development of technologies to support distributed multimedia computing, such that there is now a wide range of pilot applications under development. The design of support systems which help in the development of multimedia applications is therefore an emerging area of research. This paper discusses the requirements of distributed multimedia applications with respect to their support environments. A number of experimental systems are then described which intend to provide the necessary facilities for multimedia applications. Particular focus is placed on the Lancaster system which provides multimedia support for open distributed systems.
2 citations
21 Sep 1992
TL;DR: The aim of the work at Lancaster is to develop a distributed multimedia application platform providing support for building groupware style applications (in which groups of users interact) that takes into account current standards activities such as ISO's Open Distributed Processing standard.
Abstract: The aim of our work at Lancaster is to develop a distributed multimedia application platform. Such a platform must provide tools to enable programmers to construct distributed applications which make use of continuous media such as audio and video. If the platform is to be of use as part of a large scale distributed system, it must also take into account current standards activities such as ISO's Open Distributed Processing (ODP) standard without sacrificing the potential for high-performance necessary to support demanding media types such as high-resolution video [Blair,9l].Section 2 describes such a platform. As a result of a major applications survey and end-user study [Williams,91a], we decided to concentrate on providing support for building groupware style applications (in which groups of users interact). This decision to focus on groups has impacted on all areas of the platform. In section 3 we discuss our model of groups and explore its impact. Section 4 details our experiences of using such a platform, section 5 outlines our plans for future work and section 6 contains some concluding remarks.
1 citations