A formal method for synthesizing optimized protocol converters and its application to mobile data networks

As mobile information networks are expanding rapidly, we expect to integrate voice, paging, electronic mail and other wireless information services. Interworking units that perform protocol conversion at the boundaries of different networks will play an important role. In this paper, we propose an efficient algorithm for constructing optimized protocol converters to achieve interoperability between heterogeneous data networks. This algorithm first derives constraints from two given protocols, and apply the constraints to channel specifications, thus removing message sequences that do not contribute to system progress. Then, an optimized converter is generated from a given service specification, the two protocol specifications and the modified channel specifications. A reduction relation is used to compare the service specification and the constructed internetworking system in order to deal with the problem of nondeterministic services. Compared with related works, our method has two advantages: (1) it generates an optimized converter; (2) it can be applied to the case that the service specification is nondeterministic. The application of the method to mobile networks is given by an example. This revised version was published online in June 2006 with corrections to the Cover Date.     

A possible defective estimation of antineutrophil cytoplasmic antibodies in systemic lupus erythematosus due to the coexistence of periodontitis: preliminary observations

The Family Environment Scale has been used extensively in family research since first being published. However, despite its appeal both conceptually and empirically, doubts have been raised over the scale's reliability. This article presents normative and reliability data for the Family Environment Scale from a large, combined sample of adolescents. Means and standard deviations were generally found to be in line with those reported in the scale's manual; however, estimates of internal consistency for most subscales could be considered inadequate for research purposes.     

A theory of industry-level activity for understanding the adoption of interorganizational systems

Increasingly we wish to ask and research questions about the adoption of interorganizational systems and electronic commerce at the industry level but are hampered by the lack of a theory of concerted purposeful action at this large level of analysis. In this paper we give the outlines of such a theory and indicate the uses to which it can be put. Particular attention is paid to how the routine day-to-day activities of the firms and support organizations that make up an industry group can be coordinated in such a way that we can speak of an industry as engaged in purposeful activity. We contend that only through a deep understanding of the possibilities and nature of routine coordinated activity at this level can issues concerning promotion, implementation and adoption of interorganizational systems by whole industries be properly framed.     

Retinal vascular changes in congenital hypertrophy of the retinal pigment epithelium

The overlying retinal blood vessels were abnormal in five cases of congenital hypertrophy of the retinal pigment epithelium. This illustrated the well-recognized association between outer retinal degeneration and obliteration of the overlying retinal vasculature. The proposed pathophysiological mechanisms, however, seem inadequate to explain completely the morphological changes of the retinal blood vessels in the presence of atrophy of the outer retina.     

Bistability and hysteresis in the organization of apparent motion patterns.

In a paradigm for which 2 distinct patterns are perceived for the same stimulus, perceptual hysteresis (persistence of a percept despite parameter change to values favoring the alternative pattern) and temporal stability (persistence despite intrinsic propensities toward spontaneous change) are interdependent. Greater persistence during parameter change reduces temporal stability, slowing the rate of parameter change reduces hysteresis by increasing opportunity for spontaneous change, and increasing temporal stability (by enlarging the stimulus) increases hysteresis. Hysteresis results in the perception of parametrically disfavored patterns; a parameter can influence a percept without specifying it. The visual system thus exhibits time-dependent behavior analogous to dynamical behavior observed in other systems, both physical and biological, for which there is competition among alternative patterns that vary in relative stability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of temporal relations by pigeons.

In 4 experiments, pigeons were tested on a duration comparison task involving the successive presentation of two visual stimuli that varied in duration from trial to trial. Following presentation of the durations, 2 choice keys were lit, and reinforcement for choices was based on the temporal relation between durations of the pair. In Exp 1, the range of durations was varied over conditions. Responding changed as an orderly function of the ratio of the 2 durations. There was a decrease in discrimination accuracy as average duration increased over conditions. In Exp 2, Ss were transferred from a task involving spatially differentiated choices to one involving hue-differentiated choices. Performance was similar to that of Exp 1. In Exp 3, Ss were exposed to a single duration range that included many durations from the 4 ranges of Exp 1. Discrimination accuracy was comparable on 3 problem duration categories within this range and declined slightly for problems in the 4th and longest category. Manipulation of absolute reinforcement rate in Exp 4 resulted in no change in discrimination accuracy, suggesting that the decline in accuracy over conditions of Exp 1 could not be attributed to decreases in reinforcement rate that accompanied lengthier durations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An approach to testing specifications

An approach to testing the consistency of specifications is explored, which is applicable to the design validation of communication protocols and other cases of step-wise refinement. In this approach, a testing module compares a trace of interactions obtained from an execution of the refined specification (e.g., the protocol specification) with the reference specification (e.g., the communication service specification). Nondeterminism in reference specifications presents certain problems. Using an extended finite state transition model for the specifications, a strategy for limiting the amount of nondeterminacy is presented. An automated method for constructing a testing module for a given reference specification is discussed. Experience with the application of this testing approach to the design of a transport protocol and a distributed mutual exclusion algorithm is described.     

The efficiency of the particle acceleration in a jet pipe

In jet-mills the grinding material is accelerated in a jet pipe by means of expanding gas. The invested energy cannot be completely converted into kinetic energy of the particles because there are energy losses caused by wall friction, the slip between gas and particles, and the unconsumed kinetic energy of the gas at the pipe exit. The efficiency is defined as the ratio of the kinetic energy of the particles at the exit of the pipe and the total applied energy. With an assumption about the velocity distribution in the pipe, a formula is derived for the velocity ratio at the end of the pipe. This ratio, the load, and the geometrical sizes of the pipe influence the efficiency of the particle acceleration.