3,728 research outputs found

    Loop Equations and the Topological Phase of Multi-Cut Matrix Models

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    We study the double scaling limit of mKdV type, realized in the two-cut Hermitian matrix model. Building on the work of Periwal and Shevitz and of Nappi, we find an exact solution including all odd scaling operators, in terms of a hierarchy of flows of 2×22\times 2 matrices. We derive from it loop equations which can be expressed as Virasoro constraints on the partition function. We discover a ``pure topological" phase of the theory in which all correlation functions are determined by recursion relations. We also examine macroscopic loop amplitudes, which suggest a relation to 2D gravity coupled to dense polymers.Comment: 24p

    Nanoparticle-coated microcrystals

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    Coprecipitation provides a rapid high-yield method for self-assembly of nanoparticles on the surface of flat water-soluble crystalline surfaces and a simple immobilisation technique prior to storage or thermal and chemical modification

    Exact S-Matrix for 2D String Theory

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    We formulate simple graphical rules which allow explicit calculation of nonperturbative c=1c=1 SS-matrices. This allows us to investigate the constraint of nonperturbative unitarity, which indeed rules out some theories. Nevertheless, we show that there is an infinite parameter family of nonperturbatively unitary c=1c=1 SS-matrices. We investigate the dependence of the SS-matrix on one of these nonperturbative parameters. In particular, we study the analytic structure, background dependence, and high-energy behavior of some nonperturbative c=1c=1 SS-matrices. The scattering amplitudes display interesting resonant behavior both at high energies and in the complex energy plane.Comment: 42p

    Macroscopic nn-Loop Amplitude for Minimal Models Coupled to Two-Dimensional Gravity: Fusion Rules and Interactions

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    We investigate the structure of the macroscopic nn-loop amplitude obtained from the two-matrix model at the unitary minimal critical point (m+1,m)(m+1,m). We derive a general formula for the nn-resolvent correlator at the continuum planar limit whose inverse Laplace transform provides the amplitude in terms of the boundary lengths i\ell_{i} and the renormalized cosmological constant tt. The amplitude is found to contain a term consisting of (t)n3\left( \frac{\partial} {\partial t} \right)^{n-3} multiplied by the product of modified Bessel functions summed over their degrees which conform to the fusion rules and the crossing symmetry. This is found to be supplemented by an increasing number of other terms with nn which represent residual interactions of loops. We reveal the nature of these interactions by explicitly determining them as the convolution of modified Bessel functions and their derivatives for the case n=4n=4 and the case n=5n=5. We derive a set of recursion relations which relate the terms in the nn-resolvents to those in the (n1)(n-1)-resolvents.Comment: 30 pages, Latex, figures: figures have been introduced to represent our results on the resolvents. A better formula for the resolvents has been put and the section on residual interactions has been expanded to a large exten

    Bayesian Spatiotemporal Pattern and Eco-climatological Drivers of Striped Skunk Rabies in the North Central Plains

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    Citation: Raghavan, R. K., Hanlon, C. A., Goodin, D. G., Davis, R., Moore, M., Moore, S., & Anderson, G. A. (2016). Bayesian Spatiotemporal Pattern and Eco-climatological Drivers of Striped Skunk Rabies in the North Central Plains. Plos Neglected Tropical Diseases, 10(4), 16. doi:10.1371/journal.pntd.0004632Striped skunks are one of the most important terrestrial reservoirs of rabies virus in North America, and yet the prevalence of rabies among this host is only passively monitored and the disease among this host remains largely unmanaged. Oral vaccination campaigns have not efficiently targeted striped skunks, while periodic spillovers of striped skunk variant viruses to other animals, including some domestic animals, are routinely recorded. In this study we evaluated the spatial and spatio-temporal patterns of infection status among striped skunk cases submitted for rabies testing in the North Central Plains of US in a Bayesian hierarchical framework, and also evaluated potential eco-climatological drivers of such patterns. Two Bayesian hierarchical models were fitted to point-referenced striped skunk rabies cases [n = 656 (negative), and n = 310 (positive)] received at a leading rabies diagnostic facility between the years 2007-2013. The first model included only spatial and temporal terms and a second covariate model included additional covariates representing eco-climatic conditions within a 4km(2) home-range area for striped skunks. The better performing covariate model indicated the presence of significant spatial and temporal trends in the dataset and identified higher amounts of land covered by low-intensity developed areas [Odds ratio (OR) = 3.41; 95% Bayesian Credible Intervals (CrI) = 2.08, 3.85], higher level of patch fragmentation (OR = 1.70; 95% CrI = 1.25, 2.89), and diurnal temperature range (OR = 0.54; 95% CrI = 0.27, 0.91) to be important drivers of striped skunk rabies incidence in the study area. Model validation statistics indicated satisfactory performance for both models; however, the covariate model fared better. The findings of this study are important in the context of rabies management among striped skunks in North America, and the relevance of physical and climatological factors as risk factors for skunk to human rabies transmission and the space-time patterns of striped skunk rabies are discussed

    Open String Star as a Continuous Moyal Product

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    We establish that the open string star product in the zero momentum sector can be described as a continuous tensor product of mutually commuting two dimensional Moyal star products. Let the continuous variable κ[ 0,)\kappa \in [~0,\infty) parametrize the eigenvalues of the Neumann matrices; then the noncommutativity parameter is given by θ(κ)=2tanh(πκ/4)\theta(\kappa) =2\tanh(\pi\kappa/4). For each κ\kappa, the Moyal coordinates are a linear combination of even position modes, and the Fourier transform of a linear combination of odd position modes. The commuting coordinate at κ=0\kappa=0 is identified as the momentum carried by half the string. We discuss the relation to Bars' work, and attempt to write the string field action as a noncommutative field theory.Comment: 30 pages, LaTeX. One reference adde

    Stringy Instantons in SU(N) N=2 Non-Conformal Gauge Theories

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    In this paper we explicitly obtain the leading corrections to the SU(N) N=2 prepotential due to stringy instantons both in flat space-time and in the presence of a non-trivial graviphoton background field. We show that the stringy corrections to the prepotential are expressible in terms of the elementary symmetric polynomials. For N>2 the theory is not conformal; we discuss the introduction of an explicit dependence on the string scale \alpha' in the low-energy effective action through the stringy non-perturbative sector.Comment: 22 pages, 1 figur

    Enantioselective Construction of Acyclic Quaternary Carbon Stereocenters: Palladium-Catalyzed Decarboxylative Allylic Alkylation of Fully-Substituted Amide Enolates

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    We report a divergent and modular protocol for the preparation of acyclic molecular frameworks containing newly created quaternary carbon stereocenters. Central to this approach is a sequence composed of a (1) regioselective and -retentive preparation of allyloxycarbonyl-trapped fully substituted stereodefined amide enolates and of a (2) enantioselective palladium-catalyzed decarboxylative allylic alkylation reaction using a novel bisphosphine ligand
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