The main purpose of this paper is to show that, for any L(n) such that L(n)logn and [L(n)/n]0, L(n) space bounded alternating on-line Turing machines with only universal states are less powerful than ordinary L(n) space bounded alternating on-line Turing machines. Closure properties are also discussed.

It has already been known that there exists an infinite hierarchy of the classes of sets of square tapes accepted by deterministic space-bounded two-dimensional Turing machines with spaces below log m. This paper shows that there exists an infinite hierarchy of the classes of sets of square tapes accepted by nondeterministic space-bounded two-dimensional Turing machines with spaces less than or equal to log m.

We introduce alternating multihead finite automata with constant leaf-sizes (AMHFACLs), and investigate several properties of these automata. The main results of this paper are as follows: (1) two-way sensing AMHFACLs can be simulated by two-way nondeterministic simple multihead finite automata, (2) for one-way AMHFACLs, k+1 heads are better than k, and (3) for one-way alternating simple multihead finite automata with constant leaf-sizes, sensing versions are more powerful than non-sensing versions.

A copper vapor laser performance by using a metal-vapor-complex reaction (CuAlBr3) is reported. The laser operation is obtained at a low temperature without external heating because of the AlBr3 vapors evaporation at a room temperature. The copper vapor laser using this metal-vapor-complex reaction has an advantage of deposition-free of a metalilc copper to the laser tube wall, which is different from the copper halide and the organometallic copper lasers.

This paper gives a hierarchical property on the number of reversals of real-time counter machines. That is, we show that for any k1, a real-time counter machine with 2k+1 reversals is more powerful than one with k reversals.

A 5λ/2 rat-race-type directional coupler for arbitrary power divisions with high isolation and a method of improvement on its matching bandwidth are described. A close agreement between the theoretical and measured scattering parameters is observed also.

This paper introduces a space bounded alternating one-way multihead Turing machine with only universal states, and investigates fundamental properties of this machine. We show for example that for any function L such that [L(n)/n]0, (1) there is a set in [U2-HTM(0)], but not in [Nk-HTM(L(n))], and there is a set in [N2-HTM(0)], but not in [Uk-HTM(L(n))], (2) for each k1, [Uk-HTM(L(n))][U(k+1)-HTM(L(n))], and (3) [Uk-HTM(L(n))][Nk-HTM(L(n))][Dk-HTM(L(n))], where [Uk-HTM(L(n))] denotes the class of sets accepted by L(n) space bounded alternating one-way k-head Turing machines with only universal states, and [Nk-HTM(L(n))]([Dk-HTM(L(n))] denotes the class of sets accepted by L(n) space bounded nondeterministic (deterministic) one-way k-head Turing machines.