A New Look at Bandwidth Latency Tradeoffs

Concerns about propagation delay have dominated the discussion of latency, bandwidth and their effect on distributed applications. In this paper, we argue that the relevant latency measure for applications is the Application Data Unit (ADU) Latency, defined as the time between the sending of an ADU and its receipt. Since ADUs are often large, ADU latency is influenced by throughput as well as propagation delay. We investigated the effects the effects of ADU latency with an experimental study of several applications. The applications used Distributed Shared Memory as an interprocess communications mechanism, constraining the ADUs to page sized units. The applications were run on an Ethernet, an experimental ATM LAN, and using ATM on an experimental high-speed WAN. The measured results were used to normalize results gathered by inserting an experimental ATM switch output port controller in the network to create tunable delays. The results conclusively demonstrate the effect of ADU latency on distributed application response time. The experiments give a precise characterization of the effect of varying bandwidth and propagation delay on a real system, and suggest promising directions for further improving application performance in future networks

H. Jefferson Powell on the American Constitutional Tradition: A Conversation

Jefferson Powell\u27s recent book, The Moral Tradition of American Constitutionalism, was the point of departure for a series of short papers and conversations held in March of 1996 at the Notre Dame Law School. The conversation began with a presentation by Professor Joseph Vining. His remarks were followed by a free-flowing conversation, loosely orchestrated by Professor Robinson, among the participants. After a break, the conversation was restarted with a presentation by Professor Maura Ryan, followed once again by a loosely orchestrated conversation. We turn first to Joseph Vining

H. Jefferson Powell on the American Constitutional Tradition: A Conversation

Jefferson Powell\u27s recent book, The Moral Tradition of American Constitutionalism, was the point of departure for a series of short papers and conversations held in March of 1996 at the Notre Dame Law School. The conversation began with a presentation by Professor Joseph Vining. His remarks were followed by a free-flowing conversation, loosely orchestrated by Professor Robinson, among the participants. After a break, the conversation was restarted with a presentation by Professor Maura Ryan, followed once again by a loosely orchestrated conversation. We turn first to Joseph Vining

Architecture and Performance of the Mether Network Shared Memory

Mether is a Network Shared Memory (NSM). It allows applications on autonomous computers connected by a network to share a segment of memory. NSMs offer the attraction of a simple abstraction for shared state, i.e., shared memory. NSMs have a potential performance problem in the cost of remote references, which is typically solved by grouping memory into larger units such as pages, and caching pages. While Mether employs grouping and caching to reduce the average memory reference delay, it also removes the need for many remote references (page faults) by providing a facility with relaxed consistency requirements. Applications ported from a multiprocessor supercomputer with shared memory to a 16-workstation Mether configuration showed a cost/performance advantage of over 300 in favor of the Mether system. While Mether is currently implemented for Sun-3 and Sun-4 systems connected via Ethernet, other characteristics (such as a choice of page sizes and a semaphore-like access mode useful for process synchronization) should suit it to a wide variety of networks. A reimplementation for an alternate configuration employing packet-switched networks is in progress

The interdependence of behavioral and somatic health: implications for conceptualizing health and measuring treatment outcomes

<b>Purpose:</b> The interdependence of behavioral and somatic aspects of various health conditions warrants greater emphasis on an integrated care approach.<br><br> <b>Theory:</b> We propose that integrated approaches to health and wellness require comprehensive and empirically-valid outcome measures to assess quality of care.<br><br> <b>Method:</b> We discuss the transition from independent to integrated treatment approaches and provide examples of new systems for integrated assessment of treatment outcome.<br><br> <b>Results:</b> Evidence suggests that support for an independent treatment approach is waning and momentum is building towards more integrated care. In addition, research evidence suggests integrated care improves health outcomes, and both physicians and patients have favorable impressions of integrated care.<br><br> <b>Conclusions:</b> As treatment goals in the integrated perspective expand to take into account the intimate relationships among mental illness, overall health, and quality of life, clinicians need to develop outcome measures that are similarly comprehensive. Discussion: Increased recognition, by researchers, providers, and insurers, of the interdependence between behavioral and physical health holds great promise for innovative treatments that could significantly improve patients' lives

Phylogenetic relationships among the Asian tortoises of the genus Indotestudo (Reptilia: Testudines: Testudinidae)

Based on variation in 1094 bp of the mitochondrial cytochrome b gene among members of the genus Indotestudo from southern Asia ( I. elongata ), south-western India ( I. travancorica ), and eastern Indonesia ( I. forstenii ), I. travancorica is most similar genetically to I. elongata (3.7% divergence), and strongly divergent from I. forstenii (5.5 to 5.9%). Individuals of I. forstenii with and without a nuchal scute differ genetically at less than 0.7%. Our analysis offers no support for the hypothesis that Indonesian populations of I. forstenii represent introductions of I. travancorica from India. The recognition of three nominal species ( I. elongata, I. forstenii and I. travancorica ) in the genus is thus warrante

Sexual Size Dimorphism and Body Condition in the Australasian Gannet

Funding: The research was financially supported by the Holsworth Wildlife Research Endowment. Acknowledgments We thank the Victorian Marine Science Consortium, Sea All Dolphin Swim, Parks Victoria, and the Point Danger Management Committee for logistical support. We are grateful for the assistance of the many field volunteers involved in the study.Peer reviewedPublisher PD