Bert J. Dempsey

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This paper addresses support for multi-party multimedia applications delivered across datagram wide-area networks such as the Internet. Our approach is to develop a novel retransmission protocol framework, MESH, that protects delay-sensitive multicast data streams against most network errors and delay variations. The MESH approach partitions the multicast(More)
Distribution of continuous media tra c such as digital audio and video over packet switching networks has become increasingly feasible due to a number of technology trends leading to pow erful desktop computers and high speed integrated services networks Protocols supporting the transmission of continuous media are already available In these protocols(More)
Distribution of packetized digital speech across high speed LANs has become increasingly feasible and packet voice protocols supporting audio conferencing are available These protocols must provide mechanisms to address errors and delay introduced by the network that threaten the quality of the voice playback at the receiving site A common mechanism for(More)
Background traac models are fundamental to packet-level network simulation since the background traac impacts packet drop rates, queuing delays, end-to-end delay variation, and also determines available network bandwidth. In this paper, we present a statistical characterization of wide-area IP traac based on 90-minute traces taken from a week-long trace of(More)
A reliable multicast facility extends traditional point-to-point virtual circuit reliability to oneto-many communication. Such services can provide more efficient use of network resources, a powerful distributed name binding capability, and reduced latency in multidestination message delivery. These benefits wiU be especially valuable in real-time(More)
We present the design and implementation of a digital image capture and distribution system that supports remote ultrasound ezaminations and, in particular, real-time diagnosis for these ezaminations. The system was designed in conjunction with radiologists and staff in the Department of Radiology at the University of Virginia hospital. Based on readily(More)
RATIONALE AND OBJECTIVES The authors investigated the diagnostic efficacy of compression of real-time ultrasound (US) examinations. METHODS Low- and high-compression recordings (9:1 and 15:1, respectively) of examinations were generated by using Joint Photographic Experts Group algorithms. Seven radiologists used a five-level response scale to answer(More)