Showing papers by "Musashi University published in 1994"

Seasonal change in the composition of the diet of eastern lowland gorillas

Abstract: Details are presented of the composition of the diet of eastern lowland gorillas, derived mainly from a study of their fresh trails and fecal analysis, during the course of an entire year in the tropical lowland forests of the Itebero region, Zaire. Gorillas ate 194 plant foods from 121 species and 45 families. They consumed 48 species of fruits; and 89% of fecal samples contained fruit seeds, but fruits were a relatively small part (25%) of the total number of food items. The composition of their diet changed seasonally. When consumption of fruit decreased in the long rainy and the long dry seasons, the gorillas ate, in addition to Zingiberaceae and Marantaceae, many kinds of leaf and bark, which may be an important buffer against the shortage of fruits. Gorillas also fed regularly on ants (Ponerinae), and the frequency of consumption showed small seasonal variations. From a comparison of diet composition, eastern lowland gorillas appeared to be intermediate between the other two subspecies. The choice of food showed differences in preference of fruits and insects between subspecies and may reflect high similarities within subspecies in lowland and montane forests.

Surface Tension Driven Random Motion of a Mercury Drop in HNO3 and K2Cr2O7 Solution

Abstract: An irregular motion of a mercury drop in a petri dish filled with HNO 3 and K 2 Cr 2 O 7 solutions is studied experimentally. Larger mercury globules are extended and broken into smaller droplets, while smaller ones translate or rotate randomly in an otherwise quiescent fluid owing to the non-uniform distribution of the surface tension associated with chemical reaction. The translating mercury drop shows a peculiar form like a croissant with broad convex surface perpendicular to the direction of motion. Although the direction and magnitude of the movement of the drop change randomly, the average speed is almost independent of its size if it satisfies a certain criterion. The fluctuation of velocity shows a power spectrum proportional to 1/ f α , where α is nearly equal to 1 in fairly wide frequency range. A simple analysis on the basis of the Stokes approximation is made, which explains the relation between the average speed and the drop size.