9,193 research outputs found

    Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT

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    The anti--de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Ho\v{r}ava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attentions due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Ho\v{r}ava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Ho\v{r}ava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in λ=1\lambda=1 Ho\v{r}ava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter ϵ\epsilon close to unity. Sufficiently charged flat black holes for ϵ\epsilon close to unity, and sufficiently charged positively curved black holes with ϵ\epsilon close to zero, are also unstable. The implication to the Ho\v{r}ava-Lifshitz holographic superconductor is discussed.Comment: 15 pages, 6 figures. Updated version accepted by Phys. Rev. D, with corrections to various misprints. References update

    The Lorenz number in CeCoIn5_5 inferred from the thermal and charge Hall currents

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    The thermal Hall conductivity κxy\kappa_{xy} and Hall conductivity σxy\sigma_{xy} in CeCoIn5_5 are used to determine the Lorenz number LH{\cal L}_H at low temperature TT. This enables the separation of the observed thermal conductivity into its electronic and non-electronic parts. We uncover evidence for a charge-neutral, field-dependent thermal conductivity, which we identify with spin excitations. At low TT, these excitations dominate the scattering of charge carriers. We show that suppression of the spin excitations in high fields leads to a steep enhancement of the electron mean-free-path, which leads to an interesting scaling relation between the magnetoresistance, thermal conductivity and σxy\sigma_{xy}.Comment: 6 pages, 7 figures Intro para slightly lengthened. Added 2 new re

    Phase coherence and the Nernst effect at magic angles in organic conductors

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    A giant Nernst signal was recently observed for fields near crystallographic directions in (TMTSF)2_2PF6_6. Such large Nernst signals are most naturally associated with the motion of pancake vortices. We propose a model in which phase coherence is destroyed throughout the sample except in planes closely aligned with the applied field H\bf H. A small tilt above or below the plane changes the direction and density of the penetrating vortices and leads to a Nernst signal that varies with the tilt angle of H\bf H as observed. The resistance notches at magic angles are understood in terms of flux-flow dissipation from field-induced vortices.Comment: 4 pages, 4 figure

    Pandangan Etnis Tionghoa Surabaya terhadap Budaya Penggunaan Arak 泗水华裔对运用酒文化之观点

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    Oleh karena arak di Tiongkok selain memiliki sejarah budaya penggunaan yang panjang, jenis-jenisnya banyak, dan juga digunakan dalam proses pengobatan tradisional, penelitian ini ingin menganalisis bagaimana pandangan etnis Tionghoa Surabaya terhadap budaya penggunaan arak. Apakah masih seperti yang dikatakan dalam kajian pustaka yang digunakan dalam penelitian ini, ataukah sudah ada Perubahan dalam budaya penggunaannya. Kajian pustaka yang digunakan meliputi: budaya minum arak bagi kaum perempuan; penggunaan arak dalam perayaan-perayaan tertentu; makna arak bagi kaum sastrawan; manfaat arak dalam kesehatan. Metode penelitian yang digunakan adalah kualitatif deskriptif. Hasil analisis menunjukkan bahwa ada budaya penggunaan arak yang masih sama seperti yang ditulis dalam kajian pustaka, ada yang sudah mengalami Perubahan

    The Concentration of Manganese, Copper, Zinc, Lead and Thorium in Sediments of Paka Estuary,Terengganu, Malaysia

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    14 cm cores sediments from the Paka River were analyzed for Mn, Cu, Zn, Pb and Th using the inductively coupled plasma mass spectrometer (ICP-MS). Generally, the concentrations of all elements decreased with depth and have significantly higher concentration at the surface depth of the core. The concentration of Mn and Cu have average value of 151.1 ± 59.1 mg/g dry weights and 29.2 ± 6.9 mg/g dry weights, while Zn and Pb averaged at 72.5 ± 15.5 mg/g dry weights and 54.9 ± 2.5 mg/g dry weights, respectively. Th were slightly varied widely and ranged from 0.6 mg/g dry weights to 1.4 mg/g dry weights. In this study, only Mn and Th have enrichment factor (EF) values close to unity and may therefore be considered to be predominantly terrigenous in origin. On the contrary, the higher EF values found for Cu, Zn and Pb indicate that these metals might have some influenced from the anthropogenic inpu

    The Nernst effect in high-TcT_c superconductors

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    The observation of a large Nernst signal eNe_N in an extended region above the critical temperature TcT_c in hole-doped cuprates provides evidence that vortex excitations survive above TcT_c. The results support the scenario that superfluidity vanishes because long-range phase coherence is destroyed by thermally-created vortices (in zero field), and that the pair condensate extends high into the pseudogap state in the underdoped (UD) regime. We present a series of measurements to high fields HH which provide strong evidence for this phase-disordering scenario.Comment: 21 pages, 28 figure

    A dipole lattice model of switching characteristics in ferroelectric superlattices

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