Hideo Tamura

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Common buckwheat grown in Pb-contaminated soil was found to accumulate a large amount of Pb in its leaves (8,000 mg/kg DW), stem (2,000 mg/kg DW), and roots (3,300 mg/kg DW), without significant damage. This indicates that buckwheat is a newly recognized Pb hyperaccumulator, which is defined as a plant containing over 1,000 mg/kg of Pb in its shoots on a(More)
The fern Athyrium yokoscense is known to be highly tolerant to lead toxicity, and is a lead hyperaccumulator that can accumulate over 1,000 μg g−1 of lead in its dry matter. In this work, we examined whether the gametophytic generation of A. yokoscense also resists lead toxicity like the sporophytic generation. Spore germination in A. yokoscense was more(More)
According to the Aharonov–Bohm effect, magnetic potentials have a direct significance to the motion of particles in quantum mechanics. We study this quantum effect through the scattering by several point–like magnetic fields at large separation in two dimensions. We derive the asymptotic formula for scattering amplitudes as the distances between centers of(More)
We study the asymptotic behavior of the time delay (defined as the trace of the Eisenbud–Wigner time delay operator) for scattering by potential and by magnetic field with two compact supports as the separation of supports goes to infinity. The emphasis is placed on analyzing how different the asymptotic formulae are in potential and magnetic scattering.(More)
We study the semiclassical asymptotic behavior of the spectral shift function and of its derivative in magnetic scattering by two solenoidal fields in two dimensions under the assumption that the total magnetic flux vanishes. The system has a trajectory oscillating between the centers of two solenoidal fields. The emphasis is placed on analysing how the(More)
For the last one and a half decades it has been known that the exponential product formula holds also in norm in nontrivial cases. In this note, we review the results on its convergence in norm as well as pointwise of the integral kernels in the case for Schrödinger operators, with error bounds. Optimality of the error bounds is elaborated. Mathematics(More)
This paper describes the scalar processor of the VPP500. The 64-bit long instruction word (LIW) architecture allows the issue of up to three operations every clock cycle. Notable features of the architecture are the PC-relative conditional branch operations, asynchronous operations to allow out-of-order execution, and interruption facility which can handle(More)
We study the asymptotic behavior of scattering amplitudes for the scattering of Dirac particles in two dimensions when electromagnetic fields with small support shrink to point–like fields. The result is strongly affected by perturbations of scalar potentials and the asymptotic form changes discontinuously at half–integer fluxes of magnetic fields even for(More)