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Field‐effect transistors that employ an electrolyte in place of a gate dielectric layer can accumulate ultrahigh‐density carriers not only on a well‐defined channel (e.g., a two‐dimensional surface) but also on any irregularly shaped channel material. Here, on thin films of 95% pure metallic and semiconducting single‐walled carbon nanotubes (SWNTs), the Fermi level is continuously tuned over a very wide range, while their electronic transport and absorption spectra are simultaneously monitored. It is found that the conductivity of not only the semiconducting but also the metallic SWNT thin films steeply changes when the Fermi level reaches the edges of one‐dimensional subbands and that the conductivity is almost proportional to the number of subbands crossing the Fermi level, thereby exhibiting a one‐dimensional nature of transport even in a tangled network structure and at room temperature.

In the summer of 1988, a vegetation survey of the Siberian taiga was conducted in a discontinuous permafrost zone of northern China where a destructive fire had occurred in the spring of 1987. The dominant forest cover of this area was larch, with spruce forests occurring in wet valleys and pine forests on steep, dry slopes. The vertical structure of forests showed that the spruce forests were preceded by larch forests; however, most of the larch forests were self-renewable probably because their habitats were too dry for spruce trees to compete. In larch forests, the 1987 fire seriously damaged perennial herbs; in spruce forests, however, most of the herbaceous plants were protected by wet conditions of their habitats, except feather mosses, which could not survive in the habitat opened by fire. Many plants of the burnt habitats recovered vegetatively; in particular, the burnt stems of birch trees frequently sprouted many shoots and consequently appeared to be contributing to the rapid reestablishment of larch, which is generally preceded by birch trees in ecological succession. Pine forests were not self-renewable; however, they seemed independent of the normal course of succession by dominating dry habitats where their competitors were not successful.

A Study on Effect of Heterogeneity of Oxygen Concentration and Temperature Distributions in a Combustion Chamber on Combustion and Emissions of Diesel Engine " Satoshi TSUDA 7Hidenori KOSAKA, and Tetsuya AIZAWA Department ofMbchanical andAerospace Engineering 7bkyo lhstitute offechnologn 2-12-1 O-okayama, Mbguro-kza fokyo 152-8552 .L4R4N