8,012 research outputs found

    Relativistic mean field theory for deformed nuclei with pairing correlations

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    We develop a relativistic mean field (RMF) description of deformed nuclei with the pairing correlations in the BCS approximation. The treatment of the pairing correlations for nuclei with the Fermi surface being close to the threshold of unbound states needs a special attention. To this end, we take the delta function interaction for the pairing interaction with the hope to pick up those states with the wave function being concentrated in the nuclear region and perform the standard BCS approximation for the single particle states generated by the RMF theory with deformation. We apply the RMF + BCS method to the Zr isotopes and obtain a good description of the binding energies and the nuclear radii of nuclei from the proton drip line to the neutron drip line.Comment: the version to be published in Progress of Theoretical Physic

    Studies on organic semiconductors. 15: Effects of the substituents on the photoconductivities of substituted anthracenes

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    The photocurrents of the substituted anthracenes, 1,5-diacetylanthracene (2), 1-acetylanthracene (3), 9-acetylanthracene (4), 1,5-dichloroanthracene (5), 1,5-diethylanthracene (6), 1,5-dimethoxyanthracene (7), 9-cyanoanthracene (8), and anthracene (1) were measured by using their surface type cells in nitrogen. The compounds of (1), (5), (6), (7), and (8) showed the photocurrent spectra which corresponded to the absorption spectra of their evaporated films. In the cases of (2) and (3), however, the anomalous photocurrent appeared in the threshold region of their absorption spectra. The appearance of the anomalous photocurrent was characteristic of anthracenes having the acetyl group at 1- and/or 5-position. The magnitude of the photocurrents of the 1,5-disubstituted anthracenes was similar to that of (1). The photocurrents of the monosubstituted anthracenes were smaller than that of (1). Among the monosubstituted anthracenes, the compound (4) showed no photocurrent under the same conditions. Contrary to the results obtained in the cases of phenazines, the photoconductivities of the anthracene derivatives became better in air

    Substituent effects on the electrical conductivities of the phenazine derivatives

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    The and/or photoconductivities of 16 substituted phenazines having methoxy, hydroxy, chloro, nitro, amino or t-butyl group at 1-, 2-, 1, 6- or 2,7- positions of the phenazine ring measured by using the surface type cells. The energy gaps of the dark conductivities in the range 2.0 to 2.3 were independent of the kinds and the positions of the substituent groups, although the photo-absorption wavelength of the evaporated films changed with them. No correlation between photoconductivity and fluorescence was observed. The photocurrent was affected by the position of the substituents; namely, the photocurrents of the 1,6-di-substituted phenazines. When the substituent at 1,6-positions was hydroxy or amino group, however, the photocurrents decreased. The photocurrents decreased drastically in the presence of oxygen

    Baryons from instantons in holographic QCD

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    We consider aspects of dynamical baryons in a holographic dual of QCD that is proposed on the basis of a D4/D8-brane configuration. We construct a soliton solution carrying a unit baryon number and show that it is given by an instanton solution of four-dimensional Yang-Mills theory with fixed size. The Chern-Simons term on the flavor D8-branes plays a crucial role of protecting the instanton from collapsing to zero size. By quantizing the collective coordinates of the soliton, we work out the baryon spectra. Negative-parity baryons as well as baryons with higher spins and isospins can be obtained in a simple manner.Comment: 25 pages, v2: references added, minor changes, v3: PTP-style, minor correction

    Preparations of methoxynitrophenazines and their photoconductivities

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    Eight methoxynitrophenazines with a methoxy group at the 1 or 2 position and a nitro group at the 6-, 7-, 8- or 9-position of the phenazine ring 1,6, 1,7. 1,8, 1,9, 2,6, 2,7, 2,8 and 2,9 were prepared and their photocurrents were measured by illuminating the surface-type cell with white light from a W lamp under a N atmosphere at room temp. The photocurrents of 1-nitrophenazine 6 and 2-nitrophenazine 7 are compared with those of the methoxynitrophenazines. The photocurrent (i sub p) increases with increasing light intensity (I), thus satisfying log i varies as n log I. The n values are 0.5-1.0. When the nitro group is located at the beta-position of the phenazine ring, the photocurrent becomes larger owing to the electron withdrawing property of the nitro group. On the other hand, the photocurrents of phenazines with the nitro group at the Alpha-position are extremely small. The photoconductivities of methoxynitrophenazines are lower in air

    Chiral Sigma Model with Pion Mean Field in Finite Nuclei

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    The properties of infinite matter and finite nuclei are studied by using the chiral sigma model in the framework of the relativistic mean field theory. We reconstruct an extended chiral sigma model in which the omega meson mass is generated dynamically by the sigma condensation in the vacuum in the same way as the nucleon mass. All the parameters of chiral sigma model are essentially fixed from the hadron properties in the free space. In nuclear matter, the saturation property comes out right, but the incompressibility is too large and the scalar and vector potentials are about a half of the phenomenological ones, respectively. This fact is reflected to the properties of finite nuclei. We calculate N = Z even-even mass nuclei between N = 16 and N = 34. The extended chiral sigma model without the pion mean field leads to the result that the magic number appears at N = 18 instead of N = 20 and the magic number does not appear at N = 28 due to the above mentioned nuclear matter properties. The latter problem, however, could be removed by the introduction of the finite pion mean field with the appearance of the magic number at N = 28. We find that the energy differences between the spin-orbit partners are reproduced by the finite pion mean field which is completely a different mechanism from the standard spin-orbit interaction.Comment: 19 pages, 9 figures. Prog. Theor. Phys. to be publishe

    Requirement of the FATC domain of protein kinase Tel1 for localization to DNA ends and target protein recognition

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    Two large phosphatidylinositol 3-kinase-related protein kinases (PIKKs), ATM and ATR, play a central role in the DNA damage response pathway. PIKKs contain a highly conserved extreme C-terminus called the FRAP-ATM-TRRAP-C-terminal (FATC) domain. In budding yeast, ATM and ATR correspond to Tel1 and Mec1, respectively. In this study, we characterized functions of the FATC domain of Tel1 by introducing substitution or truncation mutations. One substitution mutation, termed tel1-21, and a truncation mutation, called tel1- ├Ä"C, did not significantly affect the expression level. The tel1-21 mutation impaired the cellular response to DNA damage and conferred moderate telomere maintenance defect. In contrast, the tel1-├Ä"C mutation behaved like a null mutation, conferring defects in both DNA damage response and telomere maintenance. Tel1-21 protein localized to DNA ends as effectively as wild-type Tel1 protein, whereas Tel1-├Ä"C protein failed. Introduction of a hyperactive TEL1-hy mutation suppressed the tel1-21 mutation but not the tel1-├Ä"C mutation. In vitro analyses revealed that both Tel1-21 and Tel1-├Ä"C proteins undergo efficient autophosphorylation but exhibit decreased kinase activities toward the exogenous substrate protein, Rad53. Our results show that the FATC domain of Tel1 mediates localization to DNA ends and contributes to phosphorylation of target proteins. ┬ę 2015 Ogi, Goto, Ghosh, et al

    Study of the effect of the tensor correlation in oxygen isotopes with the charge- and parity-projected Hartree-Fock method

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    Recently, we developed a mean-field-type framework which treats the correlation induced by the tensor force. To exploit the tensor correlation we introduce single-particle states with the parity and charge mixing. To make a total wave function have a definite charge number and a good parity, the charge number and parity projections are performed. Taking a variation of the projected wave function with respect to single-particle states a Hartree-Fock-like equation, the charge- and parity-projected Hartree-Fock equation, is obtained. In the charge- and parity-projected Hartree-Fock method, we solve the equation selfconsistently. In this paper we extend the charge- and parity-projected Hartree-Fock method to include a three-body force, which is important to reproduce the saturation property of nuclei in mean-field frameworks. We apply the charge- and parity-projected Hartree-Fock method to sub-closed-shell oxygen isotopes (14O, 16O, 22O, 24O, and 28O) to study the effect of the tenor correlation and its dependence on neutron numbers. We obtain reasonable binding energies and matter radii for these nuclei. It is found that relatively large energy gains come from the tensor force in these isotopes and there is the blocking effect by occupied neutron orbits on the tensor correlation
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