13,708 research outputs found

    Electromagnetic Coulomb Gas with Vector Charges and "Elastic'' Potentials : Renormalization Group Equations

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    We present a detailed derivation of the renormalization group equations for two dimensional electromagnetic Coulomb gases whose charges lie on a triangular lattice (magnetic charges) and its dual (electric charges). The interactions between the charges involve both angular couplings and a new electromagnetic potential. This motivates the denomination of ``elastic'' Coulomb gas. Such elastic Coulomb gases arise naturally in the study of the continuous melting transition of two dimensional solids coupled to a substrate, either commensurate or with quenched disorder

    The formation of silver /I/ chloride by the action of silver /I/ ion on carbon tetrachloride in 2-butanol and methanol

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    Formation of silver chloride by action of silver ion on carbon tetrachloride in 2-butanol and methano

    AN UNWELCOME EMPIRE: JAPANESE IMPERIALISM AS THE YELLOW PERIL IN BRITAIN AND THE UNITED STATES IN AND AROUND THE SINO-JAPANESE AND RUSSO-JAPANESE WARS.

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    This thesis is about Western perceptions of Japan’s early imperialist years and aims to address how Britain and America perceived the expansion of Meiji Japan. In doing so the period spanning from the Sino-Japanese to the Russo-Japanese War is taken as the core area of study, with the victory of Japan in both of these conflicts marking the point in time where it emerged as an imperial power. As such anti-Japanese prejudices will be examined to show how some in the West regarded this ascendency with contempt as the virtue of being an imperial state with the privileges of empire which came something which should be reserved for the white, Christian nations who possessed a history of such endeavours. In order to establish a competent assessment of this I have structured this work in such a way which sees two intense chapters being presented focusing on the years surrounding these conflicts. In these chapters Japan’s relations with the West, primarily Britain and the United States, will be looked at focusing on the differing political and societal opinions as to whether or not Japan’s emergence as a global power constituted a legitimate threat. The former of these conflicts saw Japan’s emergence as an imperial power whilst the latter saw it burst onto the world stage. For this period of study I have used materials from the popular media as well as governmental publications so to provide an encompassing image. Following the defeat of Russia in 1905 the idea of Japan as the epitome of the yellow peril was more engrained in western circles. In America especially this is most vociferous with ideas of exclusion and anti-Japanese prejudices not being difficult to find. Across this period however, Britain was more reserved in their attitudes towards Japan and although similar examples can be found they were always the more accepting of Japan which the signing of the Anglo-Japanese Alliance is testament to. By bringing together a number of different strands surrounding this topic a range of material is used collating a range of ideas and arguments, something where a study with greater parameters than those permitted here would be of greater use, providing a more thorough and encompassing investigation

    A New Phase of Tethered Membranes: Tubules

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    We show that fluctuating tethered membranes with {\it any} intrinsic anisotropy unavoidably exhibit a new phase between the previously predicted ``flat'' and ``crumpled'' phases, in high spatial dimensions dd where the crumpled phase exists. In this new "tubule" phase, the membrane is crumpled in one direction but extended nearly straight in the other. Its average thickness is RGLνtR_G\sim L^{\nu_t} with LL the intrinsic size of the membrane. This phase is more likely to persist down to d=3d=3 than the crumpled phase. In Flory theory, the universal exponent νt=3/4\nu_t=3/4, which we conjecture is an exact result. We study the elasticity and fluctuations of the tubule state, and the transitions into it.Comment: 4 pages, self-unpacking uuencoded compressed postscript file with figures already inside text; unpacking instructions are at the top of file. To appear in Phys. Rev. Lett. November (1995

    Superfluid Bosons and Flux Liquids: Disorder, Thermal Fluctuations, and Finite-Size Effects

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    The influence of different types of disorder (both uncorrelated and correlated) on the superfluid properties of a weakly interacting or dilute Bose gas, as well as on the corresponding quantities for flux line liquids in high-temperature superconductors at low magnetic fields are reviewed, investigated and compared. We exploit the formal analogy between superfluid bosons and the statistical mechanics of directed lines, and explore the influence of the different "imaginary time" boundary conditions appropriate for a flux line liquid. For superfluids, we discuss the density and momentum correlations, the condensate fraction, and the normal-fluid density as function of temperature for two- and three-dimensional systems subject to a space- and time-dependent random potential as well as conventional point-, line-, and plane-like defects. In the case of vortex liquids subject to point disorder, twin boundaries, screw dislocations, and various configurations of columnar damage tracks, we calculate the corresponding quantities, namely density and tilt correlations, the ``boson'' order parameter, and the tilt modulus. The finite-size corrections due to periodic vs. open "imaginary time" boundary conditions differ in interesting and important ways. Experimental implications for vortex lines are described briefly.Comment: 78 pages, RevTex, 4 figures included (sorry, there are no ps-files for the remaining 2 figures; if needed, please send mail to [email protected]); brief erratum appended (2 pages

    Topological transitions and freezing in XY models and Coulomb gases with quenched disorder: renormalization via traveling waves

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    We study the two dimensional XY model with quenched random phases and its Coulomb gas formulation. A novel renormalization group (RG) method is developed which allows to study perturbatively the glassy low temperature XY phase and the transition at which frozen topological defects (vortices) proliferate. This RG approach is constructed both from the replicated Coulomb gas and, equivalently without the use of replicas, using the probability distribution of the local disorder (random defect core energy). By taking into account the fusion of environments (i.e charge fusion in the replicated Coulomb gas) this distribution is shown to obey a Kolmogorov's type (KPP) non linear RG equation which admits travelling wave solutions and exhibits a freezing phenomenon analogous to glassy freezing in Derrida's random energy models. The resulting physical picture is that the distribution of local disorder becomes broad below a freezing temperature and that the transition is controlled by rare favorable regions for the defects, the density of which can be used as the new perturbative parameter. The determination of marginal directions at the disorder induced transition is shown to be related to the well studied front velocity selection problem in the KPP equation and the universality of the novel critical behaviour obtained here to the known universality of the corrections to the front velocity. Applications to other two dimensional problems are mentionned at the end.Comment: 86 pages, 15 eps files include

    B(H) Constitutive Relations Near H_c1 in Disordered Superconductors

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    We provide a self-contained account of the B vs. H constitutive relation near H_c1 in Type II superconductors with various types of quenched random disorder. The traditional Abrikosov result B ~ [ln (H - H_c1)]^{-2}, valid in the absence of disorder and thermal fluctuations, changes significantly in the presence of disorder. Moreover, the constitutive relations will depend strongly on the type of disorder. In the presence of point disorder, B ~ (H - H_c1)^{3/2} in three-dimensional (thick) superconductors, as shown by Nattermann and Lipowsky. In two-dimensional (thin film) superconductors with point disorder, B ~ (H - H_c1). In the presence of parallel columnar disorder, we find that B ~ exp[-C / (H - H_c1)] in three dimensions, while B ~ exp[-K / (H - H_c1)^{1/2}] in two dimensions. In the presence of nearly isotropically splayed disorder, we find that B ~ (H - H_c1)^{3/2} in both two and three dimensions.Comment: 37 pages, 12 figures included in text; submitted to Physica

    Sinai model in presence of dilute absorbers

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    We study the Sinai model for the diffusion of a particle in a one dimension random potential in presence of a small concentration ρ\rho of perfect absorbers using the asymptotically exact real space renormalization method. We compute the survival probability, the averaged diffusion front and return probability, the two particle meeting probability, the distribution of total distance traveled before absorption and the averaged Green's function of the associated Schrodinger operator. Our work confirms some recent results of Texier and Hagendorf obtained by Dyson-Schmidt methods, and extends them to other observables and in presence of a drift. In particular the power law density of states is found to hold in all cases. Irrespective of the drift, the asymptotic rescaled diffusion front of surviving particles is found to be a symmetric step distribution, uniform for x<1/2ξ(t)|x| < {1/2} \xi(t), where ξ(t)\xi(t) is a new, survival length scale (ξ(t)=Tlnt/ρ\xi(t)=T \ln t/\sqrt{\rho} in the absence of drift). Survival outside this sharp region is found to decay with a larger exponent, continuously varying with the rescaled distance x/ξ(t)x/\xi(t). A simple physical picture based on a saddle point is given, and universality is discussed.Comment: 21 pages, 2 figure
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