1,623 research outputs found

    Relational Regulation and Chinese Real Estate Investment in London: Moving Beyond the Territorial Trap

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    National governments, urban authorities and supra-national bodies increasingly see the provision of new housing as a core priority. There has been a strong emphasis on reforming the regulatory environments that exist within geographical territories and making them more welcoming to inward investment. However, such outlooks we claim often fall into a territorial trap and give too much prominence to the regulations and policy environments found in recipient destinations. The paper argues instead for a more recursive focus on the ways in which decisions taken in ‘source’ and ‘host’ locations need to be understood as part of a mutually constitutive system of governance. Using the example of Chinese residential investment into London, it argues that investment trends, processes and outcomes reflect a recursive combination of regulatory and political changes in both the city and within China, with the latter becoming increasingly influential. As we show, the Chinese Communist Party has been exerting greater control over the activities of Chinese real estate enterprises and what products are ‘permitted’ for investment and how this should be done. The paper reflects on the implications for recent academic and policy writings on urban territorial competition

    Thermal Diffusivities of Functionalized Pentacene Semiconductors

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    We have measured the interlayer and in-plane (needle axis) thermal diffusivities of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn). The needle axis value is comparable to the phonon thermal conductivities of quasi-one dimensional organic metals with excellent pi-orbital overlap, and its value suggests that a significant fraction of heat is carried by optical phonons. Furthermore, the interlayer (c-axis) thermal diffusivity is at least an order of magnitude larger, and this unusual anisotropy implies very strong dispersion of optical modes in the interlayer direction, presumably due to interactions between the silyl-containing side groups. Similar values for both in-plane and interlayer diffusivities have been observed for several other functionalized pentacene semiconductors with related structures.Comment: 9 pages, including 4 figures; submitted to Applied Physics Letter

    Holographic fermions in external magnetic fields

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    We study the Fermi level structure of 2+1-dimensional strongly interacting electron systems in external magnetic field using the AdS/CFT correspondence. The gravity dual of a finite density fermion system is a Dirac field in the background of the dyonic AdS-Reissner-Nordstrom black hole. In the probe limit the magnetic system can be reduced to the non-magnetic one, with Landau-quantized momenta and rescaled thermodynamical variables. We find that at strong enough magnetic fields, the Fermi surface vanishes and the quasiparticle is lost either through a crossover to conformal regime or through a phase transition to an unstable Fermi surface. In the latter case, the vanishing Fermi velocity at the critical magnetic field triggers the non-Fermi liquid regime with unstable quasiparticles and a change in transport properties of the system. We associate it with a metal-"strange metal" phase transition. Next we compute the DC Hall and longitudinal conductivities using the gravity-dressed fermion propagators. For dual fermions with a large charge, many different Fermi surfaces contribute and the Hall conductivity is quantized as expected for integer Quantum Hall Effect (QHE). At strong magnetic fields, as additional Fermi surfaces open up, new plateaus typical for the fractional QHE appear. The somewhat irregular pattern in the length of fractional QHE plateaus resemble the outcomes of experiments on thin graphite in a strong magnetic field. Finally, motivated by the absence of the sign problem in holography, we suggest a lattice approach to the AdS calculations of finite density systems.Comment: 34 pages, 14 figure

    Viscoelastic response of sonic band-gap materials

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    A brief report is presented on the effect of viscoelastic losses in a high density contrast sonic band-gap material of close-packed rubber spheres in air. The scattering properties of such a material are computed with an on-shell multiple scattering method, properties which are compared with the lossless case. The existence of an appreciable omnidirectional gap in the transmission spectrum, when losses are present, is also reported.Comment: 5 pages, 4 figures, submitted to PR

    Comment on "Gravitationally Induced Neutrino-Oscillation Phases"

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    We critically examine the recent claim (gr-qc/9603008) of a ``new effect'' of gravitationally induced quantum mechanical phases in neutrino oscillations. A straightforward exercise in the Schwarzschild coordinates appropriate to a spherically symmetric non-rotating star shows that, although there is a general relativistic effect of the star's gravity on neutrino oscillations, it is not of the form claimed, and is too small to be measured.Comment: Plain LaTeX, 7 pages, no figure

    Time-Symmetric Initial Data for Multi-Body Solutions in Three Dimensions

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    Time-symmetric initial data for two-body solutions in three dimensional anti-deSitter gravity are found. The spatial geometry has constant negative curvature and is constructed as a quotient of two-dimensional hyperbolic space. Apparent horizons correspond to closed geodesics. In an open universe, it is shown that two black holes cannot exist separately, but are necessarily enclosed by a third horizon. In a closed universe, two separate black holes can exist provided there is an additional image mass.Comment: 12 pages, harvmac macro, minor changes in wordin

    On completeness of orbits of Killing vector fields

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    A Theorem is proved which reduces the problem of completeness of orbits of Killing vector fields in maximal globally hyperbolic, say vacuum, space--times to some properties of the orbits near the Cauchy surface. In particular it is shown that all Killing orbits are complete in maximal developements of asymptotically flat Cauchy data, or of Cauchy data prescribed on a compact manifold. This result gives a significant strengthening of the uniqueness theorems for black holes.Comment: 16 pages, Latex, preprint NSF-ITP-93-4

    Gluing Initial Data Sets for General Relativity

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    We establish an optimal gluing construction for general relativistic initial data sets. The construction is optimal in two distinct ways. First, it applies to generic initial data sets and the required (generically satisfied) hypotheses are geometrically and physically natural. Secondly, the construction is completely local in the sense that the initial data is left unaltered on the complement of arbitrarily small neighborhoods of the points about which the gluing takes place. Using this construction we establish the existence of cosmological, maximal globally hyperbolic, vacuum space-times with no constant mean curvature spacelike Cauchy surfaces.Comment: Final published version - PRL, 4 page

    Angular momentum-mass inequality for axisymmetric black holes

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    In these notes we describe recent results concerning the inequality m≥∣J∣m\geq \sqrt{|J|} for axially symmetric black holes.Comment: 7 pages, 1 figur
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