Software fault-tolerance by design diversity DEDIX: A tool for experiments

The use of multiple versions of a computer program, independently designed from a common specification, to reduce the effects of an error is discussed. If these versions are designed by independent programming teams, it is expected that a fault in one version will not have the same behavior as any fault in the other versions. Since the errors in the output of the versions are different and uncorrelated, it is possible to run the versions concurrently, cross-check their results at prespecified points, and mask errors. A DEsign DIversity eXperiments (DEDIX) testbed was implemented to study the influence of common mode errors which can result in a failure of the entire system. The layered design of DEDIX and its decision algorithm are described

The UCLA Design Diversity Experiment (DEDIX) system: A distributed testbed for multiple-version software

To establish a long-term research facility for experimental investigations of design diversity as a means of achieving fault-tolerant systems, a distributed testbed for multiple-version software was designed. It is part of a local network, which utilizes the Locus distributed operating system to operate a set of 20 VAX 11/750 computers. It is used in experiments to measure the efficacy of design diversity and to investigate reliability increases under large-scale, controlled experimental conditions

ATM as a memory interconnect in a Desk Area Network

ATM has been successfully used in Wide Area Networks (WAN) and Local Area Networks (LAN). A possible next step in this evolution is to use ATM for memory interconnect. This paper discusses how ATM can fulfill the functional and performance requirements in a memory interconnect, and the implications this will have for external ATM communication. We conclude that ATM can be used as a memory interconnect. It can meet the throughput requirements but will have problems with the latency requirements for the transfer of small cache lines. The fixed 48 byte payload in ATM results in inefficient use of bandwidth and increased latency. The ATM and the ATM Adaptation Layers do not have sufficient functionality and must be extended to meet memory interconnect requirements. Using ATM internally in the memory interconnect has a limited synergy effect when the system is connected to an ATM based LAN or WAN. Keywords Data Communication, ATM, Desk Area Network, memory, multiprocessors. 1 INTRODUCTION..

Lutein - An important carotenoid in human nutrition

Carotenoids are one of the most used natural colorants due to their non-toxic nature and wide occurrence. Carotenoids are commonly found in orange, yellow and green fruits and vegetables. Lutein is a yellow pigment ranking among carotenoids. Lutein occurs in green vegetables, fruits like mango and papaya, red paprika, alfalfa, algae, yellow corn, and marigold flower. In animals it occurs in egg yolks and also in the macular region of the eye retina. Humans are not able to synthesize lutein depending entirely on natural sources or dietary supplements

Use of Pressure-Redistributing Support Surfaces Among Elderly Hip Fracture Patients Across the Continuum of Care: Adherence to Pressure Ulcer Prevention Guidelines

Purpose: To estimate the frequency of use of pressure-redistributing support surfaces (PRSS) among hip fracture patients and to determine whether higher pressure ulcer risk is associated with greater PRSS use. Design and Methods: Patients (n = 658) aged ≥65 years who had surgery for hip fracture were examined by research nurses at baseline and on alternating days for 21 days. Information on PRSS use and pressure ulcer risk factors was recorded at each assessment visit. Other information was obtained by interview and chart review. Results: A PRSS was observed at 36.4% of the 5,940 study visits. The odds of PRSS use were lower in the rehabilitation setting (adjusted odds ratio [OR] 0.4, 95% confidence interval [CI] 0.3–0.6), in the nursing home (adjusted OR 0.2, 95% CI 0.1–0.3), and during readmission to the acute setting (adjusted OR 0.6, 95% CI 0.4–0.9) than in the initial acute setting. There was wide variation in frequency of PRSS use by admission hospital, even after adjusting for pressure ulcer risk factors. The relationships between PRSS use and pressure ulcer risk factors were not strong. Implications: In this study of hip fracture patients, adherence to guidelines for PRSS use was low and was based more on facility-related factors than on patient risk. There is an urgent need for health care providers to improve strategies for the prevention of pressure ulcers in high-risk patients