Locally Localized Gravity Models in Higher Dimensions

We explore the possibility of generalizing the locally localized gravity model in five space-time dimensions to arbitrary higher dimensions. In a space-time with negative cosmological constant, there are essentially two kinds of higher-dimensional cousins which not only take an analytic form but also are free from the naked curvature singularity in a whole bulk space-time. One cousin is a trivial extension of five-dimensional model, while the other one is in essence in higher dimensions. One interesting observation is that in the latter model, only anti-de Sitter ($AdS_p$) brane is physically meaningful whereas de Sitter ($dS_p$) and Minkowski ($M_p$) branes are dismissed. Moreover, for $AdS_p$ brane in the latter model, we study the property of localization of various bulk fields on a single brane. In particular, it is shown that the presence of the brane cosmological constant enables bulk gauge field and massless fermions to confine to the brane only by a gravitational interaction. We find a novel relation between mass of brane gauge field and the brane cosmological constant.Comment: 20 pages, LaTex 2e, revised version (to appear in Phys. Rev. D

Renormalizability of Massive Gravity in Three Dimensions

We discuss renormalizability of a recently established, massive gravity theory with particular higher derivative terms in three space-time dimensions. It is shown that this massive gravity is certainly renormalizable as well as unitary, so it gives us a physically interesting toy model of perturbative quantum gravity in three dimensions.Comment: 13 pages, no figure

Ni-impurity effects on the superconducting gap of La2−x_{2-x}Srx_{x}CuO4_4 studied from the magnetic field and temperature dependence of the electronic specific heat

The magnetic field and temperature dependence of the electronic specific heat $C_{\rm el}$ have been systematically investigated in $\rm La_{2-{\it x}}Sr_{\it x}Cu_{1-{\it y}}Ni_{\it y}O_4$ (LSCNO) in order to study Ni-impurity effects on the superconducting (SC) gap. In LSCNO with $x$=0.15 and $y$=0.015, the value of $\gamma$ ($\equiv C_{\rm el}/T$) at $T$=0 K, $\gamma_0$, is enhanced under the magnetic field $H$ applied along the $\bm c$-axis. The increment of $\gamma_0$, $\Delta \gamma_0$, follows the Volovik relation $\Delta \gamma_0$=$A\sqrt{H}$, characteristic of the SC gap with line nodes, with prefactor $A$ similar to that of a pure sample. The $C_{\rm el}/T$ vs. $T$ curve under $H$=0 shows a d-wave-like SC anomaly with an abrupt increase at $T_{\rm c}$ and $T$-linear dependence at $T$$\ll$$T_{\rm c}$, although the $\gamma_0$-value in the $C_{\rm el}/T$ vs. $T$ curve increases with increasing Ni concentrations. Interestingly, as the SC part of $C_{\rm el}/T$, $C_{\rm el}/T$$-$$\gamma_0$$\equiv$$\gamma_{\rm s}$, decreases in LSCNO, $T_{\rm c}$ is reduced in proportion to the decrease of $\gamma_{\rm s}$. These findings can be explained phenomenologically by a simple model in which Ni impurities bring about strong pair breaking at the edges of the coherent nodal part of the Fermi surface but in the vicinity of the nodes of the SC gap. The reduction of the SC condensation energy $U_0$ in LSCNO, evaluated from $C_{\rm el}$ at $T$ {0.3em}\raisebox{0.4ex}{$<$} {-0.75em}\raisebox{-.7ex}{$\sim$} {0.3em}$T_{\rm c}$, is also understood by the same model.Comment: 7 pages, 6 figures, accepted in Phys. Rev.

The competitive effect of adenosine-5'-triphosphate against the stimulating and inhibiting actions of 2,4-dinitrophenol on the mitochondrial respiration

Effect of ATP and substrates on 2,4-dinitrophenol-induced adenosine triphcsphatase (E. C. 3.6. 1. 4.) activity and respiration of isolated rat liver mitochondria has been investigated. 1. The oxidation of sodium succinate inhibited the action of 2, 4-DNP on the induction of adenosine triphosphatase activity in the mitochondria. 2. A moderately large amount of sodium succinate restored the suppressed mitochondrial respiration due to 2, 4-DNP. 3. Adenosine-5'-triphosphate (ATP) restored quantitatively the released and inhibited mitochondrial respiration due to 2,4-DNP, and its prior addition prevented also quantitatively the action of 2,4-DNP on the mitochondrial oxygen up-take. These ATP effects were oligomycin sensitive, and they were considered to manifest their actions through the phosphorylation system.</p

Bottom-up fabrication of Si nanodot transistors using the nc-Si dots solution

A new approach to fabricate nanometer-scale silicon devices is recently attracting much attention, which combines the conventional top-down silicon processing techniques and the bottom-up assembly of silicon nanodots, whose structures are controlled on the atomic scale. This technique enables to investigate the electronic states and transport properties of strongly-coupled multiple nanodots which will be crucial particularly for quantum information device applications. Various unique properties have been studied in such systems. For example, electrostatic interactions have been investigated for double Si dots [1] and for the two-dimensional Si multidots [2]. Coherent wavefunction coupling and associated quasi-molecular states have also been observed for a tunnel-coupled double Si nanodots [3]. In addition, metal-insulator transition has been investigated for an artificial lattice of self-organized nano-paraticles [4]. In this paper we propose and examine a novel technique of fabricating nanoscale transistors with a Si nanodot cluster as a channel based on the self-assembly of the nanocrystalline Si dots from the solution on the patterned SOI substrates

STM/STS Study on 4a X 4a Electronic Charge Order and Inhomogeneous Pairing Gap in Superconducting Bi2Sr2CaCu2O8+d

We performed STM/STS measurements on underdoped Bi2212 crystals with doping levels p ~ 0.11, ~ 0.13 and ~ 0.14 to examine the nature of the nondispersive 4a X 4a charge order in the superconducting state at T << Tc. The charge order appears conspicuously within the pairing gap, and low doping tends to favor the charge order. We point out the possibility that the 4a X 4a charge order will be dynamical in itself, and pinned down over regions with effective pinning centers. The pinned 4a X 4a charge order is closely related to the spatially inhomogeneous pairing gap structure, which has often been reported in STS measurements on high-Tc cuprates.Comment: 12 pages, 16 figures, to be published in Phys. Rev.