Variation of the electronic structure in systematically synthesized Sr2MO4 (M = Ti, V, Cr, Mn, and Co)

We have systematically synthesized single-crystalline thin films of layered perovskites Sr2MO4 (M = Ti, V, Cr, Mn, and Co) which cannot be obtained in a form of bulk crystal apart from M = Mn. The two-dimensional electronic structure of these M4+ oxides, ranging from a correlated insulator to a ferromagnetic metal, has been investigated by using their optical conductivity spectra with polarizations E is perpendicular to c and E is parallel to c, which reveal systematic variation of the correlated charge gap, Mott-Hubbard gap, or charge-transfer gap. Temperature dependence of the gap-transition spectra is argued in the light of possible spin and/or orbital ordering.     

Approximation algorithms for combinatorial fractional programming problems

We are concerned with a combinatorial optimization problem which has the ratio of two linear functions as the objective function. This type of problems can be solved by an algorithm that uses an auxiliary problem with a parametrized linear objective function. Because of its combinatorial nature, however, it is often difficult to solve the auxiliary problem exactly. In this paper, we propose an algorithm which assumes that the auxiliary problems are solved only approximately, and prove that it gives an approximate solution to the original problem, of which the accuracy is at least as good as that of approximate solutions to the auxiliary problems. It is also shown that the time complexity is bounded by the square of the computation time of the approximate algorithm for the auxiliary problem. As an example of the proposed algorithm, we present a fully polynomial time approximation scheme for the fractional 0–1 knapsack problem.     

Probabilistic kinetics of macroprocesses in broken microscopic reversibility

Probabilistic kinetics following the Pauli master equation without microscopic reversibility determines an asymptotic structure of macroprocesses in a coarse-grained phase space of many degrees of freedom. The structure, which is asymptotically realized, minimizes its irreversible decay rate among various candidates. This least irreversible decay rate is consistent with the assertion for the minimum K-entropy which has been argued to apply to the nonequilibrium asymptotic state. The irreversible decay rate is a state function characteristic of macrostructure on a coarse-grained time scale. Macrofluctuations, which always appear around the asymptote as fluctuations of the state function, do not obey the central limit theorem, implying that fluctuations whose characteristic times are not less than some finite value are never excluded.     

Solvable classes of discrete dynamic programming

As finite state models to represent a discrete optimization problem given in the form of an r-ddp (recursive discrete decision process), three subclasses of r-msdp (recursive monotone sequential decision process) are introduced in this paper. They all have a feature that the functional equations of dynamic programming hold and there exists an algorithm (in the sense of the theory of computation) to obtain the set of optimal policies. (In this sense, we may call them solvable classes of discrete dynamic programming.) Besides the algorithms for obtaining optimal policies, two types of representations are extensively studied for each class of r-msdp's. Other related decision problems are also discussed. It turns out that some of them are solvable while the rest of them are unsolvable.     

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)相似文献   

Synthesis of 2-O-(4-coumaroyl)-3-(4-hydroxyphenyl)lactic acid, an important intermediate of rosmarinic acid biosynthesis.

A simple method to synthesize (+/-)-2-O-(4-coumaroyl)-3-(4-hydroxyphenyl)lactic acid (1), a key intermediate in rosmarinic acid biosynthesis in higher plant cells, was established by condensation of protected 4-coumaric acid and (+/-)-3-(4-hydroxyphenyl)lactic acid followed by deprotection. A stable supply of 1 thus attained will lead to biochemical and molecular biological characterization of later steps of rosmarinic acid biosynthesis.