The question I raise in this paper is why the Japanese counterpart of the sprouting type of sluicing does not appear to show island sensitivity. I argue that this apparent difference is attributed to another well-established one between these two languages: pro- drop vs. non-pro-drop languages. Thus, sluices are not real instances of the sprouting-type but rather of the merger type, which has an overt correlate in the antecedent clause, i.e., indefinite pro in relevant cases. As substantial evidence for this proposal, I demonstrate that indefinite pro actually functions as a correlate to a sluice in Japanese by examining how it behaves with respect to scopal parallelism. Given this, it is predicted that in Japanese sluicing examples, the implicit correlates that are identified as indefinite pro can take wide scope, unlike truly implicit correlates.

Heterogeneous materials such as rock cannot be expected to have homogeneity so as to be used as structural materials. For example, in order to test large rocks more than one cubic meter, measures need to be taken against weaknesses such as internal cracks and fracture zones that can easily be overlooked in compressive strength tests. The impact-echo method could be available for evaluating strength and detecting internal defects in-situ concrete component with relatively good accuracy. In this study, measurements using the impact-echo method were carried for several types of rock specimens used at automobile crash safety tasting, and, by comparing the results with compression strength tests, the applicability of the impact-echo method for strength estimation of heterogeneous materials was evaluated.This work was supported by JSPS KAKENHI Grant Number 25420462.