High-Level Views of Distributed Executions: Convex Abstract Events

Due to the complexity of distributed applications, understanding their behaviour is a challenging task. To remedy this problem, graphical visualizations of distributed executions in the form of process-time diagrams are frequently employed. However, such process-time diagrams do not scale for long-running and complex distributed applications. To reduce the display complexity, abstract graphical views of an execution are frequently suggested. One commonly used abstraction is to group primitive events into abstract events. This paper discusses some of the problems encountered when analyzing executions at abstract levels and introduces the concept of convex abstract events. Such abstract events can be used to reason about executions at higher levels, facilitating program development, debugging, and maintenance. We discuss some fundamental aspects, such as the precedence relation and its efficient detection, for abstract events. The paper also presents a graphical representation for convex abstract events which can easily be included in process-time diagrams. Poet, our visualization tool, was enhanced with a facility to display abstract events. Using a non-trivial distributed application, examples of the resulting abstract execution visualizations are discussed.     

Formation of DNA adducts by cyproterone acetate and some structural analogues in primary cultures of human hepatocytes

To compare inductively coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectometry (GF-AAS) as the method for determining lead and cadmium in the human diet and blood, 418 diet homogenate samples and the same number of blood samples were collected from Chinese and Japanese women and were analyzed by the two methods. The results showed that our ICP-MS method is precise and accurate, being comparable to the GF-AAS method established previously. The ICP-MS method is simple and fast spending only one-tenth of the time necessary for GF-AAS and allows simultaneous analyses of lead and cadmium with low detection limits. When applied to actual sample analysis, however, ICP-MS results tend to be 10-20% lower than GF-AAS results in the analysis of lead in the diet and blood and cadmium in blood. This is possibly due to some interference in ICP-MS and matrix of samples. As the ICP-MS results could be mathematically corrected to be equivalent to the GF-AAS results, we conclude that this ICP-MS method can be used as a routine analytical method for the determination of lead and cadmium in human diet and blood samples.     

Using automatic process clustering for design recovery anddistributed debugging

Distributed applications written in Hermes typically consist of a large number of sequential processes. The use of a hierarchy of process clusters can facilitate the debugging of such applications. Ideally, such a hierarchy should be derived automatically. This paper discusses two approaches to automatic process clustering, one analyzing runtime information with a statistical approach and one utilizing additional semantic information. Tools realizing these approaches were developed and a quantitative measure to evaluate process clusters is proposed. The results obtained under both approaches are compared, and indicate that the additional semantic information improves the cluster hierarchies derived. We demonstrate the value of automatic process clustering with an example. It is shown how appropriate process clusters reduce the complexity of the understanding process, facilitating program maintenance activities such as debugging     

A personal computer program using a 4-component logit for the evaluation of ELISA calibration curves with unknown asymptotic values

A BASIC program is described for the calculation of ELISA calibration curves using a 4-component logit for the linearisation of the sigmoidal shape. The difficulty of estimating the four logit parameters without knowledge of upper and lower asymptotic values is overcome by statistical analysis of the experimental data. The program is run on an IBM-PC and the curves are plotted by a HP7475A plotter.     

Time distribution of patent information

Abandonement rates of patents in five European countries are studied. The time distribution of British patents can be described by a truncated Gauss' distribution, of Belgian patents by a Poisson's distribution. Appropriate models derived on the base of the octogonal and cubical linear vector space norms are discussed.     

Low-temperature behaviour of epoxy-rubber particulate composites

Toughness and mechanical property data are presented for a carboxyl-terminated acrylonitrile butadiene (CTBN) rubber-modified epoxy resin in the temperature range 20 to – 110° C. A toughening model based on ultimate strain capability and tear energy dissipation of the rubber, present as dispersed microscopic particles in an epoxy matrix, is used to explain the suppression of composite toughness (G _Ic ) below – 20° C. The toughness loss is attributed to a glass transition in the rubber particles, and to a secondary transition in the epoxy resin, both occurring in the range – 40 to – 80° C. Strain-tofailure and modulus measurements on bulk rubber-epoxy compounds, formulated to simulate rubber particle compositions, confirm a decrease in rubber ductility coincident with the onset of composite toughness loss. An increase in rubber tear energy associated with its transition to a rigid state can explain the observation that even at low temperatures composite toughness generally remains significantly higher than that of pure epoxy. Although the low-temperature epoxy transition reduces molecular mobility in the matrix phase, residual ductility in, and energy dissipation by, the rubber particles determine the extent of composite toughness suppression. The low-temperature data bear out the particle stretching-tearing model for toughening.     

Modeling Landslide Dambreak Flood Magnitudes: Case Study

Landslide dams typically comprise unconsolidated and poorly sorted material and are vulnerable to rapid failure and breaching, resulting in significant and sudden flood risk downstream. Hence they constitute a serious natural hazard, and rapid assessment of the likely peak flow rate is required to enable preparation of adequate mitigation strategies. To determine the relative utility and accuracy of dambreak flood forecasts, field estimates of peak outflow rates from the failure of the Poerua landslide dam in October 1999 were compared with estimates from physical laboratory modeling, empirical methods, and computer modeling. There was reasonable agreement among the field estimates, laboratory modeling, and computer modeling. Some empirical estimates were less reliable. Reasonably reliable estimates of peak outflow can be obtained from computer model routines sufficiently rapidly to be of use in an emergency management situation. The laboratory modeling demonstrated the effect of dam batter slopes and valley bed slope on peak outflow; this information could be used to refine empirical or numerical estimates of peak outflow.