The polarization dependence of the resonance wavelength of long period fiber gratings (LPFGs) that employ the photoelastic effect is investigated based on a simple model. The proposed model for estimating the birefringence of these LPFGs provides a good explanation of the experimental results.

The performance of a force feedback system is disturbed by delay that arises from the time required for transmission and processing of data. We used a psychophysical method to measure how much a user's subjective impression of elasticity associated with delays of feedback force deviated from the original physical elasticity. The results show that users' point of subjective equality (PSE) for their subjective impression of elasticity decreased as the delay of feedback force increased. We proposed a model that estimates the PSE of elasticity from the variables that can be physically measured. Another experiment was conducted to examine the model's prediction, which the results supported.

A digest is provided of work carried out at the Institute of Cancer Research to develop freehand elastography and apply it to breast investigations. Topics covered include the development of freehand elastography and its relationship to other methods, a description of the system for off-line clinical evaluation of the freehand method, comparison of the physical performances of freehand and mechanical elastography, early clinical results on 70 breast tumours, real-time imaging, quantitative elastography and psychophysical aspects of the detection and assessment of elastic lesions. Progress in developing this new medical imaging modality is occurring rapidly throughout the world and its future looks promising.

The aim of this study is to measure and quantify muscle fatigue of low back, caused by sitting on the vehicle seat for a long period of time. The authors proposed a new objective muscle fatigue index based on Principle Component Analysis utilizing the measured muscle viscoelasticity and EMG. The new index suggests an adequate correlation with the subjective fatigue.

This paper considers properties of language classes with finite elasticity in the viewpoint of set theoretic operations. Finite elasticity was introduced by Wright as a sufficient condition for language classes to be inferable from positive data, and as a property preserved by (not usual) union operation to generate a class of unions of languages. We show that the family of language classes with finite elasticity is closed under not only union but also various operations for language classes such as intersection, concatenation and so on, except complement operation. As a framework defining languages, we introduce restricted elementary formal systems (EFS's for short), called max length-bounded by which any context-sensitive language is definable. We define various operations for EFS's corresponding to usual language operations and also for EFS classes, and investigate closure properties of the family Ge of max length-bounded EFS classes that define classes of languages with finite elasticity. Furthermore, we present theorems characterizing a max length-bounded EFS class in the family Ge, and that for the language class to be inferable from positive data, provided the class is closed under subset operation. From the former, it follows that for any n, a language class definable by max length-bounded EFS's with at most n axioms has finite elasticity. This means that Ge is sufficiently large.

The mechanical impedance of silicone–gel model or chest surface has been measured and the viscoelasticity and effective vibrating radius have been obtained from the impedance. They depend on the distance between the internal block of the silicone–gel/ribs of right chest and the gel surface/skin surface. The 3–D image of internal structure is reconstructed, based on the relation between the distance from the surface and the effective vibrating radius.