The characteristics of 155 Mbps optical propagation through atmosphere at the wavelengths of 0.78 and 1.55 m over a 72 m range were measured. Two propagation characteristics were compared to examine the wavelength dependence on the rain rate and the aperture size of a receiver. An enhanced intensity exceeding the signal level measured in the absence of rain was observed at both wavelengths during 7.2 mm/h rain. The resultant bit error rate is shown to be dominated mainly by the rain-induced scintillation rather than the attenuation.

In this paper we extend Pratt's dynamic logic so as to treat assignment statements concerning Pascal-like pointers and records. We present backward transformation rules for these statements and give the formal justification of the rules by extending Pratt's program-semantics. Properties of programs which manipulate more complex data structures composed of pointers and records (e.g., linked stacks, queues, trees, etc.) can be described in our logic. We prove as an example a partial correctness assertion of a program which treats a linked stack.

This study discusses the feasibility to estimate the concentration level of Japanese document workers using computer. Based on the previous findings that dual-task scenarios increase reaction time, we hypothesized that the Kana-Kanji conversion confirmation time (KKCCT) would increase due to the decrease in cognitive resources allocated to the document task, i.e. the level of concentration on the task at hand. To examine this hypothesis, we conducted a set of experiments in which sixteen participants copied Kana text by typing and concurrently converted it into Kanji under three conditions: Normal, Dual-task, and Mental-fatigue. The results suggested the feasibility that KKCCT increased when participants were less concentrated on the task due to subtask or mental fatigue. These findings imply the potential utility of using confirmation time as a measure of concentration level in Japanese document workers.