Performance comparison of the CRAY-2 and CRAY X-MP/416 supercomputers

The serial and parallel performance of one of the world's fastest general purpose computers, the CRAY-2, is analyzed using the standard Los Alamos Benchmark Set plus codes adapted for parallel processing. For comparison, architectural and performance data are also given for the CRAY X-MP/416. Factors affecting performance, such as memory bandwidth, size and access speed of memory, and software exploitation of hardware, are examined. The parallel processing environments of both machines are evaluated, and speedup measurements for the parallel codes are given.An earlier version of this paper was presented at Supercomputing '88This work was performed under the auspices of the U.S. Department of Energy.     

A calibration approach to acoustic emission energy measurement

An approximate method for the quantitative characterization of acoustic emission sources whose signals are recorded with traditional instrumentation has been developed to evaluate the emission from a Fe-Ni alloy undergoing martensitic transformations. The calibration principle is based upon using pseudo sources of known elastic strain energy to produce a calibration curve relating a parameter of the acoustic emission signal measured (envelope strength) to the strain energy of the source. The curve can then be used to determine the strain energy of naturally occurring sources during martensitic transformations.     

An Open Model for Hypermedia and Its Application to Geographical Information Systems

This paper describes the design and implementation of a multimedia information management environment that is based on an open model for hypermedia. The model, known as Microcosm, is currently implemented in Microsoft Windows and supports many different media types. The open nature of the model and the separation of the links from the data, allows links to be applied across any application running under Windows or the OS/2 version 2 desktop, thus creating a truly integrated environment. One example, which is, discussed in the paper, is the integration of a hypermedia database with a geographical information system. The paper also discusses the application of novel interfaces to dynamic media within a hypermedia system, including the use of moving icons (micons).     

A protocol to provide verifiable proof of identity and unforgeable transaction receipts

An identity verification scheme that uses a public authentication channel to validate a private authentication channel belonging to the individual who wishes to prove his identity is described. The user can prove his identity by demonstrating that he can authenticate (suitably chosen) messages in the private channel. It also provides certified receipts for transactions whose legitimacy can later be verified by impartial arbiters who do not need to be designated in advance or be involved in the transaction at the time it takes place.<>     

Lymphocyte recirculation, exercise, and immune responses

OBJECTIVES: Visual evoked potentials (VEPs) show abnormal responses in newly-diagnosed insulin-dependent diabetic (IDDM) patients. Electrophysiological methods allow one to dissect and explore different structures contributing to neural conduction in the visual pathways. The aim of our work was to assess whether the VEP abnormalities are due to impaired function of the retinal layers and/or a delayed conduction in the postretinal visual pathways. METHODS: Simultaneous recordings of VEP and pattern-electroretinogram (PERG) were performed at two intervals (at entry of the study and after 3 months) in 14 newly-diagnosed IDDM patients (age: 24.8+/-6.8 years; duration of disease: 3+/-1.5 months), and in 14 age-matched control subjects. RESULTS: In comparison with control subjects, IDDM patients showed: VEP P100 latencies significantly delayed (P < 0.01), a significant impairment of all PERG parameters (P < 0.01) and retinocortical time (RCT, difference between VEP P100 and PERG P50 latencies) and latency window (LW, difference between VEP N75 and PERG P50 latencies) also significantly increased (P < 0.01). All electrophysiological parameters were not significantly changed when retested after 3 months. No correlations were found between VEP P100 latency, RCT, LW and PERG parameters. CONCLUSIONS: Impaired PERG indicates an involvement of the innermost retinal layers; increased values of RCT and LW represent an index of delayed neural conduction in the postretinal visual pathways. Therefore two sources, one retinal (impaired PERG) and one postretinal (delayed RCT and LW), may independently contribute in to the abnormal responses of VEP observed in newly-diagnosed IDDM patients. Three months of relatively-stable metabolic control have not normalized the VEP and PERG impairment.     

Structural characteristics of biodegradable thermoplastic starch/poly(ethylene–vinyl alcohol) blends

To establish relationships among the blend composition, processing history, and the resultant properties of starch-based thermoplastics, three varieties of corn starch: (1) Waxy Maize, (2) Native Corn, and (3) high-amylose Hylon VII were extrusion-blended with poly(ethylene-vinyl alcohol) (EVOH) containing 56 mol % VOH. Wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to examine the structural characteristics of the blends. All starches were destructurized upon compounding and a fine dispersion was achieved with EVOH. The Native Corn and Hylon VII blends were phase-separated and exhibited some miscibility between the polymer components as evident in EVOH melting-point depression, smaller domain sizes, lower contrast between phases in TEM, and increased resistance to moisture and enzyme-etching treatments. Starches containing amylose exhibited complexation and crystallinity in the starch fraction, although most of the crystallinity in the blends was due to the EVOH component. Waxy Maize blends were well phase-separated with larger domain sizes and underwent phase coarsening as a function of time in the melt. When subjecting the blends to capillary flow, orientation of both starch-rich and EVOH-rich domains was observed at various compositions, with the EVOH component undergoing significantly more orientation relative to starch as evident by the presence of EVOH-rich fibrils. Finally, EVOH was found to coat the surfaces of filaments produced from the blends even at rather high levels of starch (70%), which is expected to improve moisture sensitivity and slow down the initial rate of biodegradation. © 1995 John Wiley & Sons, Inc.     

A Saponification Procedure for the Determination of Some Chlorinated Hydrocarbons in Fish

A rapid method is described for the separation and analysis of chlorinated hydrocarbon residues in Great Lakes fishes. The method involves saponification with alcoholic KOH and chromatography on activated silica gel column with petroleum ether and diethyl ether elutions. Final analysis is achieved by gas chromatography equipped with electron-capture detection system. The recovery of the chlorinated hydrocarbon residues, using the silica gel clean-up, ranged from 82 to 94% with an average standard deviation of ± 0.8. Analysis by this method of some chlorinated hydrocarbons in Lake Huron fish gave values ranging from 0.130 to 1.89 ppm for PCB, 0.018 to 0.76 ppm for DDT and metabolites, and 0.002 to 0.040 ppm for aldrin.