2,132 research outputs found

    Endoscopic Management of Pancreatic Pseudocysts

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    Recently, endoscopic interventional procedures were introduced for nonsurgical therapy of symptomatic pancreas pseudocysts. We reported 25 patients treated by endoscopic retrograde pancreas drainage (ERPD), endoscopic cystogastrostomy (ECG), or endosopic cystoduodenostomy (ECD)

    Prediction of the Atomization Energy of Molecules Using Coulomb Matrix and Atomic Composition in a Bayesian Regularized Neural Networks

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    Exact calculation of electronic properties of molecules is a fundamental step for intelligent and rational compounds and materials design. The intrinsically graph-like and non-vectorial nature of molecular data generates a unique and challenging machine learning problem. In this paper we embrace a learning from scratch approach where the quantum mechanical electronic properties of molecules are predicted directly from the raw molecular geometry, similar to some recent works. But, unlike these previous endeavors, our study suggests a benefit from combining molecular geometry embedded in the Coulomb matrix with the atomic composition of molecules. Using the new combined features in a Bayesian regularized neural networks, our results improve well-known results from the literature on the QM7 dataset from a mean absolute error of 3.51 kcal/mol down to 3.0 kcal/mol.Comment: Under review ICANN 201

    The Separable Kernel of Nucleon-Nucleon Interaction in the Bethe-Salpeter Approach

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    The dispersion relations for nucleon-nucleon (NN) T-matrix in the framework of Bethe-Salpeter equation for two spin one-half particle system and with separable kernel of interaction are considered in the paper. The developed expressions are applied for construction of the separable kernel of interaction for S partial-waves in singlet and triplet channels. We calculate the low energy scattering parameters and the phase shifts and also the deuteron binding energy with the separable interaction. The approach can be easily extended to higher partial-waves for NN-scattering and other reactions (anti N N-, pi N-scattering).Comment: RevTex 4 style, 9 pages, 1 figur

    Relativistic Contributions to Deuteron Photodisintegration in the Bethe-Salpeter Formalism

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    In plane wave one-body approximation the reaction of deuteron photodisintegration is considered in the framework of the Bethe-Salpeter formalism for two-nucleon system. Results are obtained for deuteron vertex function, which is the solution of the homogeneous Bethe-Salpeter equation with a multi-rank separable interaction kernel, with a given analytical form. A comparison is presented with predictions of non-relativistic, quasipotential approaches and the equal time approximation. It is shown that important contributions come from the boost in the arguments of the initial state vertex function and the boost on the relative energy in the one-particle propagator due to recoil.Comment: 29 pages, 6 figure

    Relativistic three-particle scattering equations

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    We derive a set of relativistic three-particle scattering equations in the three-particle c.m. frame employing a relativistic three-particle propagator suggested long ago by Ahmadzadeh and Tjon in the c.m. frame of a two-particle subsystem. We make the coordinate transformation of this propagator from the c.m. frame of the two-particle subsystem to the three-particle c.m. frame. We also point out that some numerical applications of the Ahmadzadeh and Tjon propagator to the three-nucleon problem use unnecessary nonrelativistic approximations which do not simplify the computational task, but violate constraints of relativistic unitarity and/or covariance.Comment: 5pages, text and one ps figure (in revtex) include

    Developing a Web Site to Provide Geologic Data and Map Products for Allen County, Indiana

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    This poster was presented at the 2007 meeting of the Digital Mapping Techniques Conference in Columbia, South Carolina, May 20-23, 2007.The Internet is becoming the medium of choice for delivering geologic information to both technical users and the general public. The Indiana Geological Survey (IGS) is currently creating a Web-based glacial and bedrock geologic map site for Allen County in northeastern Indiana. Allen County is the site of Fort Wayne, Indiana’s second largest city, and lies within IGS mapping and outreach priority areas based on population density and transportation corridors. This Web site provides detailed geologic information in an area that continues to experience pressure on natural resources by a large population and expanding transportation network. It is anticipated that the information from the Web site will be widely used by the general public and by industry and government entities. The Allen County Web site includes an Internet map server (IMS), as well as illustrations, educational summaries, and discussions of geologic maps, terrain images, and databases that complement the IMS. The site provides a front-end to the IGS enterprise geodatabases, which contain information used simultaneously for research and for viewing by the general public. The geodatabase systems allow maps and data to be efficiently created, managed, updated, and distributed. Maps provided on the Allen County Web site include: (1) digital elevation model terrain, (2) Landsat imagery, (3) surficial geology, (4) drift thickness, (5) bedrock topography, (6) bedrock geology, and (7) water-table elevation. Technical database information includes: (1) lithologic information compiled from water-well information in the Indiana Department of Natural Resources, Division of Water well records, (2) natural gamma-ray geophysical log data, (3) stratigraphic test hole data, and (4) petroleum-well data. The development of the Web site was funded by the IGS and the Central Great Lakes Geologic Mapping Coalition.U.S. Geological Surve

    Relativistic three-body bound states and the reduction from four to three dimensions

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    Beginning with an effective field theory based upon meson exchange, the Bethe-Salpeter equation for the three-particle propagator (six-point function) is obtained. Using the one-boson-exchange form of the kernel, this equation is then analyzed using time-ordered perturbation theory, and a three-dimensional equation for the propagator is developed. The propagator consists of a pre-factor in which the relative energies are fixed by the initial state of the particles, an intermediate part in which only global propagation of the particles occurs, and a post-factor in which relative energies are fixed by the final state of the particles. The pre- and post-factors are necessary in order to account for the transition from states where particles are off their mass shell to states described by the global propagator with all of the particle energies on shell. The pole structure of the intermediate part of the propagator is used to determine the equation for the three-body bound state: a Schr{\"o}dinger-like relativistic equation with a single, global Green's function. The role of the pre- and post-factors in the relativistic dynamics is to incorporate the poles of the breakup channels in the initial and final states. The derivation of this equation by integrating over the relative times rather than via a constraint on relative momenta allows the inclusion of retardation and dynamical boost corrections without introducing unphysical singularities.Comment: REVTeX, 21 pages, 4 figures, epsf.st
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