Stellar structure and compact objects before 1940: Towards relativistic astrophysics

Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal

Supporting The Real-Time Requirements Of Continuous Media In Open Distributed Processing

The field of distributed systems is now entering a stage of maturity with work focusing on standards for Open Distributed Processing (ODP). However, it is still important that standardisation remains responsive to emerging technological demands such as the emergence of distributed multimedia computing. This new field introduces continuous media data types such as digital audio and video which have new, real-time requirements which are not fully supported in current ODP proposals. This paper describes the results of collaborative research at Lancaster University and CNET, France into the handling of multimedia and continuous media in an ODP compatible framework. The aim of the paper is to provide a comprehensive statement of requirements for continuous media in ODP and to aid the evolution of standards by making specific proposals on how the evolving ODP standards could be enhanced. 1. INTRODUCTION It is now widely recognised that the combination of multimedia computing and distributed ..