Systems theory in the social sciences

[Δε διατίθεται περίληψη / no abstract available][Δε διατίθεται περίληψη / no abstract available

Polyhedral models for generalized associahedra via Coxeter elements

Motivated by the theory of cluster algebras, F. Chapoton, S. Fomin and A. Zelevinsky associated to each finite type root system a simple convex polytope called \emph{generalized associahedron}. They provided an explicit realization of this polytope associated with a bipartite orientation of the corresponding Dynkin diagram. In the first part of this paper, using the parametrization of cluster variables by their $g$-vectors explicitly computed by S.-W. Yang and A. Zelevinsky, we generalize the original construction to any orientation. In the second part we show that our construction agrees with the one given by C. Hohlweg, C. Lange, and H. Thomas in the setup of Cambrian fans developed by N. Reading and D. Speyer.Comment: 31 pages, 2 figures. Changelog: 20111106: initial version 20120403: fixed errors in figures 20120827: revised versio

Grid Databases for Shared Image Analysis in the MammoGrid Project

The MammoGrid project aims to prove that Grid infrastructures can be used for collaborative clinical analysis of database-resident but geographically distributed medical images. This requires: a) the provision of a clinician-facing front-end workstation and b) the ability to service real-world clinician queries across a distributed and federated database. The MammoGrid project will prove the viability of the Grid by harnessing its power to enable radiologists from geographically dispersed hospitals to share standardized mammograms, to compare diagnoses (with and without computer aided detection of tumours) and to perform sophisticated epidemiological studies across national boundaries. This paper outlines the approach taken in MammoGrid to seamlessly connect radiologist workstations across a Grid using an "information infrastructure" and a DICOM-compliant object model residing in multiple distributed data stores in Italy and the UKComment: 10 pages, 5 figure

Cross-Section for a K-Shell Vacancy Produced by Heavy Projectile in N an Independent-Particle-Model Atom

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Potentials for High-Energy Scattering from Hydrogenlike Atoms

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One-And-A-Half-Centered Expansion Method in Charge-Transfer Calculations of Proton-Hydrogen Scattering

Journals published by the American Physical Society can be found at http://publish.aps.org/In this paper, we undertake a feasibility study of improving the one-and-a-half-centered expansion (OHCE) method of Reading, Ford, and Becker [J. Phys. B 14, 1995 (198 1)15, 3257 (1982)]. We have explored the efficacy of an alternative method to evaluate the charge-transfer matrix elements and improved the estimated time dependence of the charge-transfer scattering amplitudes. More projectile states have been included in the calculations than used hitherto. A unitary matrix, U matrix, which can propagate the wave functions from -infinity to t, where t denotes time, has been constructed using the single-centered expansion (SCE) method. A complex basis set of nine radial s states and nine radial p states has been used in the expansion of trial wave functions for the target. Charge-transfer matrix elements have been evaluated by a Feynman integral techniqueone numerical integral using Gaussian quadrature is needed. The radial parts of the matrix elements are stored on circles and used for all the impact parameters. In a OHCE calculation, we have to choose a function beta(m)(z) to modulate the charge-transfer amplitudes. The only constraints on beta(m)(z) are beta(m)(-infinity) = 0 and beta(m)(infinity) = 1. In this paper, beta(m)(z) has been obtained from a SCE calculation. This beta(m)(z) function increases gradually in the whole collision region. It offers an improvement over the step function used in previous work. A computer code has been developed to include s and p states for the target and projectile. The calculations have been performed in the proton energy range from 30 to 250 keV. The charge transfer to the Is state has been calculated and gives good agreement with the experimental data. The proton energy ranges have been extended from the 100 keV used in previous work to 250 keV. The charge-transfer cross sections to the 2p state fit the experimental data at 30 keV and are almost the same as those calculated using the four-state, two-centered expansion method proposed by Cheshire and Gallaher [J. Phys. B 3, 813 (1970)] and Shakeshaft [Phys. Rev. A 14, 1626 (1976)]. The results of the charge exchange to the 2s state are also in fairly good agreement with the measurements of Ryding [listed in Tawara, Kato, and Nakar, At. Data Nucl. Data Tables 32, 235 (1985)]

High-Energy Calculation of K-Shell Ejection Cross-Sections as a Function of Projectile Charge

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Binding Effects in High-Energy Scattering Applied to K-Shell Ionization

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Exact Solution of One-Dimensional Schrodinger Equation with Delta-Function Potentials of Arbitrary Position and Strength

Journals published by the American Physical Society can be found at http://journals.aps.org