2,235 research outputs found

    On the gravitational field of static and stationary axial symmetric bodies with multi-polar structure

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    We give a physical interpretation to the multi-polar Erez-Rozen-Quevedo solution of the Einstein Equations in terms of bars. We find that each multi-pole correspond to the Newtonian potential of a bar with linear density proportional to a Legendre Polynomial. We use this fact to find an integral representation of the γ\gamma function. These integral representations are used in the context of the inverse scattering method to find solutions associated to one or more rotating bodies each one with their own multi-polar structure.Comment: To be published in Classical and Quantum Gravit

    Third order superintegrable systems separating in polar coordinates

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    A complete classification is presented of quantum and classical superintegrable systems in E2E_2 that allow the separation of variables in polar coordinates and admit an additional integral of motion of order three in the momentum. New quantum superintegrable systems are discovered for which the potential is expressed in terms of the sixth Painlev\'e transcendent or in terms of the Weierstrass elliptic function

    Psi-Series Solution of Fractional Ginzburg-Landau Equation

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    One-dimensional Ginzburg-Landau equations with derivatives of noninteger order are considered. Using psi-series with fractional powers, the solution of the fractional Ginzburg-Landau (FGL) equation is derived. The leading-order behaviours of solutions about an arbitrary singularity, as well as their resonance structures, have been obtained. It was proved that fractional equations of order alphaalpha with polynomial nonlinearity of order ss have the noninteger power-like behavior of order α/(1s)\alpha/(1-s) near the singularity.Comment: LaTeX, 19 pages, 2 figure

    Hamiltonians separable in cartesian coordinates and third-order integrals of motion

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    We present in this article all Hamiltonian systems in E(2) that are separable in cartesian coordinates and that admit a third-order integral, both in quantum and in classical mechanics. Many of these superintegrable systems are new, and it is seen that there exists a relation between quantum superintegrable potentials, invariant solutions of the Korteweg-De Vries equation and the Painlev\'e transcendents.Comment: 19 pages, Will be published in J. Math. Phy

    General-relativistic Model of Magnetically Driven Jet

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    The general scheme for the construction of the general-relativistic model of the magnetically driven jet is suggested. The method is based on the usage of the 3+1 MHD formalism. It is shown that the critical points of the flow and the explicit radial behavior of the physical variables may be derived through the jet ``profile function."Comment: 12 pages, LaTex, no figure

    Conceptual framework for scenarios development in the Water futures and Solutions project

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    The major purpose of the Water Futures & Solutions (WFaS) initiative is to develop a set of adaptable resilient and robust solutions and a framework to facilitate access to and guidance through them by decision makers facing a variety of water-related challenges to sustainable evelopment, and a set of optional pathways to achieve plausible sustainable development goals by 2050. The WFaS Initiative addresses the multidimensional aspects of the water system and is guided by stakeholders representing these various aspects. The Initiative views freshwater systems as being strongly interweaved with human activities (Economy, Society) and Nature as a whole. Dynamics and health of freshwater systems is critical to human well- being. The Initiative will go beyond scenario production and model comparisons and will focus on exploring solutions and necessary innovations to address the growing water challenges. Solutions can be combinations of technological innovations, regulatory approaches, manageent or institutional changes that improve the balance of water supply and demand, improve water quality, or reduce water-related risks for society. Solutions will often be embedded in and cut across all sectors of social and economic activities. In order to represent the aspirations and interdependencies as described above, the conceptual framework has been developed, to communicate project results to the target audiences. This document describes this conceptual framework that will be used: -to support development of qualitative water scenarios -to identify and select critical dimensions of the water scenarios -to guide integration of scenarios with quantitative models -to guide integration of information from various data sources into the scenarios -to support development and assessment of solutions -to support collaboration between project and stakeholder groups -to facilitate presentation of results to target audiences The WFaS conceptual framework is developed using the 'concept maps' technique (Caqas and Carff, 2005; Novak and Caqas, 2006b). Concept maps method was develop to represent knowledge in an organized way. It allows practitioners to represent concepts and specific relationships between concepts. It is flexible enough to adapt to different knowledge domains to support better understanding and communication between individuals and groups from different backgrounds

    Canonical Quantization of the Gowdy Model

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    The family of Gowdy universes with the spatial topology of a three-torus is studied both classically and quantum mechanically. Starting with the Ashtekar formulation of Lorentzian general relativity, we introduce a gauge fixing procedure to remove almost all of the non-physical degrees of freedom. In this way, we arrive at a reduced model that is subject only to one homogeneous constraint. The phase space of this model is described by means of a canonical set of elementary variables. These are two real, homogeneous variables and the Fourier coefficients for four real fields that are periodic in the angular coordinate which does not correspond to a Killing field of the Gowdy spacetimes. We also obtain the explicit expressions for the line element and reduced Hamiltonian. We then proceed to quantize the system by representing the elementary variables as linear operators acting on a vector space of analytic functionals. The inner product on that space is selected by imposing Lorentzian reality conditions. We find the quantum states annihilated by the operator that represents the homogeneous constraint of the model and construct with them the Hilbert space of physical states. Finally, we derive the general form of the quantum observables of the model.Comment: 13 pages, Revte

    Geroch--Kinnersley--Chitre group for Dilaton--Axion Gravity

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    Kinnersley--type representation is constructed for the four--dimensional Einstein--Maxwell--dilaton--axion system restricted to space--times possessing two non--null commuting Killing symmetries. New representation essentially uses the matrix--valued SL(2,R)SL(2,R) formulation and effectively reduces the construction of the Geroch group to the corresponding problem for the vacuum Einstein equations. An infinite hierarchy of potentials is introduced in terms of 2×22\times 2 real symmetric matrices generalizing the scalar hierarchy of Kinnersley--Chitre known for the vacuum Einstein equations.Comment: Published in ``Quantum Field Theory under the Influence of External Conditions'', M. Bordag (Ed.) (Proc. of the International Workshop, Leipzig, Germany, 18--22 September 1995), B.G. Teubner Verlagsgessellschaft, Stuttgart--Leipzig, 1996, pp. 228-23

    A pilot trial to evaluate the acute toxicity and feasibility of tamoxifen for prevention of breast cancer.

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    Epidemiological and experimental evidence indicates that oestrogens are involved in the carcinogenic promotion of human breast cancer. We have undertaken a pilot trial of tamoxifen, an anti-oestrogen, compared to placebo given to 200 women at a high risk of developing breast cancer. The results of this trial show that acute toxicity is low and that accrual and compliance are satisfactory. Furthermore, biochemical monitoring of lipids and clotting factors indicate that tamoxifen may reduce the risk of cardiovascular deaths. At this stage no untoward long-term risks have been identified, and it is therefore proposed that a large multicentre trial should be started
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