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- Author or Editor: J. Kim x
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Abstract
We show that in dimension 8, a semiflat metric is flat and that in dimension (8k+4) higher than 8, a semiflat metric does not necessarily imply flat.
Abstract
The different approaches of the monostandard activation analysis are evaluated critically in order to put them into a common formulation. The nuclear data relevant to the method, which are selected and verified by experiment, are presented for general application. The accuracy of the method for multielement analysis is discussed by comparing the analytical results of the various reference materials from different methods and laboratories with those from monostandard activation analysis.
Abstract
We show that every 4-dimensional anti-Khler manifold is Einstein and locally symmetric. In particular any 4-dimensional anti-Khler manifold with zero scalar curvature is flat.
Abstract
The concentrations of3H,137Cs and239,240Pu were determined in surface seawaters collected at 21 sampling stations around Korea from October of 1994 to May of 1995. The results were consistent with the past data observed in the North Pacific. The concentrations of3H and137Cs did not show much difference no matter where the samples were taken. Due to the limited distribution of sampling points, no systematic change in3H and137Cs levels with latitude was observed. On the other hand,239,240Pu concentration in the East Sea (Japan Sea) was somewhat higher than that in the South and the Yellow Seas, although the data on239,240Pu concentration were not enough to explain the reason. The activity ratios of239,240Pu/137Cs in surface seawater ranged from 0.13% to 0.44% with a mean of 0.25±0.08%. The activity ratios were lower than those of the global fall-out level, 1.1%. This result presumably arose from the different behavior of the two radionuclides in seawater.
Abstract
We prove a reduction theorem of codimension for real submanifolds of quaternionic hyperbolic spaces as a quaternionic analogue corresponding to those in Cecil [2], Erbacher [4], Kawamoto [8], Kwon and the second author [10] and Okumura [13].
Abstract
Let M be the closed, simply connected, 4-manifold with nonnegative sectional curvature, called a nonnegatively curved 4-manifold, with an effective and isometric Z m -action for a positive integer m ≧ 617. Assume that Z m acts trivially on the homology of M. The goal of this short paper is to prove that if the fixed point set of any nontrivial element of Z m has at most one two-dimensional component, then M is homeomorphic to S 4, # i l =1S 2 × S 2, l = 1, 2, or # j k = 1 ± CP 2, k = 1, 2, 3, 4, 5. The main strategy of this paper is to give an upper bound of the Euler characteristic χ(M) under the homological assumption of a Z m -action as above by using the Lefschetz fixed point formula.
Abstract
The average fission neutron cross-sections of the reactions233U(n, 2n)232U,60Ni(n, p)60Co and27Al(n, p)27Mg and the resonance integrals of the (n, γ)-reactions of the nuclides181Ta,176Lu,175Lu,64Ni,59Co and26Mg have been determined by the activation method following the well-known conventions. The results verify some of the existing values and present data for hitherto unknown or poorly known reactions.
Abstract
By means of differential pulse polarography, Pu ions of different oxidation states have been investigated in 1M Na2CO3 solution. Redox reactions of Pu/III/, Pu/IV/, Pu/V/ and Pu/VI/, which are mostly of irreversible nature, have been observed within the potential range of the dropping mercury electrode /DME/, from 0 to –1.5 V, against a Ag/AgCl/NaCl (3M) reference electrode. Based on the peak potential observed for each reaction, the stability of a given oxidation state in the solution could be ascertained. The redox potential of the Pu/IV/–Pu/III/ pair, which was found to be –1.0 V, indicated that the Pu/IV/ carbonate complex was of high stability. The detection sensitivity of the Pu/IV/ ion was found to be 1×10–6M.
Abstract
The compilation comprises the experimental and calculated resonance integrals of nuclides (hydrogen to fermium), for neutron capture and fission reactions. The thermal cross-sections of the corresponding reactions are also included. Whenever possible, in addition to original values of the resonance integrals, normalized values are also given. The theoretical explanation and physical meaning of the resonance integrals determined by different approaches are briefly discussed.
