Controllability problems in MSC-based testing

This is a pre-copyedited, author-produced PDF of an article accepted for publication in The Computer Journal following peer review. The definitive publisher-authenticated version [Dan, H and Hierons, RM (2012), "Controllability Problems in MSC-Based Testing", The Computer Journal, 55(11), 1270-1287] is available online at: http://comjnl.oxfordjournals.org/content/55/11/1270. Copyright @ The Authors 2011.In testing systems with distributed interfaces/ports, we may place a separate tester at each port. It is known that this approach can introduce controllability problems which have received much attention in testing from finite state machines. Message sequence charts (MSCs) form an alternative, commonly used, language for modelling distributed systems. However, controllability problems in testing from MSCs have not been thoroughly investigated. In this paper, controllability problems in MSC test cases are analysed with three notions of observability: local, tester and global. We identify two types of controllability problem in MSC-based testing. It transpires that each type of controllability problem is related to a type of MSC pathology. Controllability problems of timing are caused by races but not every race causes controllability problems; controllability problems of choice are caused by non-local choices and not every non-local choice causes controllability problems. We show that some controllability problems of timing are avoidable and some controllability problems of choice can be overcome when testers have better observational power. Algorithms are provided to tackle both types of controllability problems. Finally, we show how one can overcome controllability problems using a coordination service with status messages based on algorithms developed in this paper.EPSR

The Oracle Problem When Testing from MSCs

Message Sequence Charts (MSCs) form a popular language in which scenario-based specifications and models can be written. There has been significant interest in automating aspects of testing from MSCs. This paper concerns the Oracle Problem, in which we have an observation made in testing and wish to know whether this is consistent with the specification. We assume that there is an MSC specification and consider the case where we have entirely independent local testers (local observability) and where the observations of the local testers are logged and brought together (tester observability). It transpires that under local observability the Oracle Problem can be solved in low-order polynomial time if we use sequencing, loops and choices but becomes NP-complete if we also allow parallel components; if we place a bound on the number of parallel components then it again can be solved in polynomial time. For tester observability, the problem is NP-complete when we have either loops or choices. However, it can be solved in low-order polynomial time if we have only one loop, no choices, and no parallel components. If we allow parallel components then the Oracle Problem is NP-complete for tester observability even if we restrict to the case where there are at most two processes

Pressure and protein denaturation

Kinetic analyses have indicated that moderate hydrostatic pressures, up to some 700 atmospheres, oppose reversible and irreversible denaturations of certain enzyme systems, apparent at temperatures above the normal optimum of the enzyme reaction, as well as at lower temperatures in the presence of denaturants such as alcohol (1-4). Qualitative observations have shown that such pressures also retard the precipitation of highly purified human serum globulin and egg albumin at 65° (5) and slow the destruction of specific antitoxic activity at the same temperature (6). In this study we have obtained quantitative data with regard to the influence of various pressures, up to 10,000 pounds per sq. in., and of low concentrations of ethyl alcohol on the time course of precipitation of human serum globulin (1) at 65° and pH 6.0

The manufacture of antibodies in vitro

A protein solution with the properties of a specific antiserum to the triphenylmethane dye methyl blue has been made by treating a solution of bovine gamma-globulin and the dye with alkali and then slowly neutralizing the alkali. Some success has been obtained also in the formation of antibodies from other serum proteins and by other denaturation-renaturation procedures. By heating solutions of gamma-globulin and antigen to 57°C. for several days antisera homologous to the antigens have been prepared. This method has been used successfully with the azodye 1,3-dihydroxy-2,4,6-tri(p-azophenyl-arsonic acid) benzene and with pneumococcus polysaccharide Type III. The antipneumococcus sera were found to precipitate the polysaccharide of Type III but not those of Types I and VIII and to agglutinate pneumococci of Type III but not those of Types I and II

Synaptic Inhibition Influences the Temporal Coding Properties of Medial Superior Olivary Neurons. An in vitro Study

The medial superior olive (MSO) functions as a coincidence detector for interaural time and phase differences by integrating excitatory synaptic inputs. Recent studies demonstrating glycinergic projections to MSO neurons suggest that coincidence detection results from the temporal integration of both EPSPs and IPSPs. We examined the impact of synaptic inhibition on the temporal coding properties of gerbil MSO neurons in vitro with intracellular recordings and electrical stimulation. For low-level bilateral electric stimulation, the EPSPs summated to produce an action potential in 73% of MSO neurons if they occurred within 50–500 microseconds of one another. Synaptic inhibition became more prominent at higher stimulus amplitudes in 73% of MSO neurons, and could block an evoked action potential if the stimuli to each pathway were delivered within 250 microseconds of one another. The glycine receptor antagonist strychnine influenced the response to simulated interaural time differences. In the presence of strychnine, interstimulus delays that originally resulted in full action potential suppression were sufficient to evoke an action potential. For trains of stimuli, as stimulus intensity increased (spatial summation), or as stimulus repetition rate increased to 100–500 Hz (temporal summation), there was a decrease in the number of stimulus pulses that evoked an action potential. In the presence of strychnine, MSO neurons generated a greater percentage of action potentials to the stimulus trains. When stimulus trains were delivered bilaterally, MSO neurons fired a greater number of action potentials at specific interstimulus time differences, and were selectively inhibited at other time differences.(ABSTRACT TRUNCATED AT 250 WORDS)</jats:p

The retention of S35-labelled bovine serum albumin on normal and immunized rabbit liver tissue

The S35-label of S35-BSA was detected in the liver tissue of rabbits to the extent of 0.02 per cent (10 µg or sime 1014 molecules) of the injected material at 140 days after injection. The rate of loss of antigen at the termination of the experiment was of such an order that significant amounts would be expected to persist for at least several years. Data are reported which extend the retention data previously reported on S35-labelled hemocyanin. They indicate that amounts of the order of 0.05 per cent (25 µg.) of antigen material persist at 330 days after injection. All of the radioactivity of material retained in the liver tissue 6 weeks after injection was immunologically related to the original S35-BSA antigen. Preliminary studies are reported which indicate that the retained antigen is bound to ribonucleic acid. A new method is described for the isolation of p-azophenylsulfonate bovine serum albumin from tissue extracts by means of a Dowex 2 adsorbent